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Article Contents
Article Contents

# Motifs in evolving cooperative networks look like protein structure networks

• The structure of networks can be characterized by the frequency of different subnetwork patterns found within them. Where these frequencies deviate from what would be expected in random networks they are termed “motifs” of the network. Interestingly it is often found that networks performing similar functions evidence similar motif frequencies. We present results from a motif analysis of networks produced by peer-to-peer protocols that support cooperation between evolving nodes. We were surprised to find that their motif profiles match closely protein structure networks. It is currently an open issue as to precisely why this is.
Mathematics Subject Classification: Primary: 91A22, 91A43; Secondary: 91D30.

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# Scripts for World¶

All world elements for Widelands are defined in data/world. There are 2 main scripts:

• data/world/init.lua: This file lists all scripts that define the world elements such as critters, immovables (including trees), resources and terrains. It bootstraps the world used in our maps and also defines the editor categories.

• data/world/map_generation.lua: This file is used by the map generator. You can ignore it while designing your world, but you can add new elements to be included in automatically generated maps if you want.

Critters, immovables, resources and terrains are defined in their respective init.lua script files - each world element has its own except for the terrains, which have a common init.lua file.


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Use adaptive quiz-based learning to study this topic faster and more effectively.

# Thermodynamic processes

## Thermodynamic processes overview

A thermodynamic process is the transformation of a system from an initial state to a final state. This transformation is accompanied by changes in the pressure, volume and temperature of the system.

A state is a set of values of physical quantities (e.g. volume, pressure, temperature) that describe the properties of a system.

Thermodynamic processes are represented by pressure-volume (p-V) lines/curves. They are often drawn with arrows indicating the path taken.

Several connected p-V lines/curves are often drawn on the same axes to form a cyclical process.

An example of a cyclic process: A represents an expansion at constant pressure, B represents a decrease in pressure at constant volume, C represents a compression at constant pressure, and D represents an increase in pressure at constant volume.

## Isochoric process

p-V graph showing an different thermodynamic processes (1: isothermal, 2: isochoric, 3: isobaric, 4: adiabatic).

In an isochoric process the volume is kept constant (i.e. $\Delta V=0$). This implies that the work done by the gas is zero (i.e. $W=0$).

The change in internal energy during an isochoric process is equal to the heat supplied to the system (i.e. $\Delta U=Q$).

The p-V graph of an isochoric process is a vertical line.

$p=$pressure; $Q=$heat supplied; $T=$temperature; $\Delta U=$change in internal energy; $V=$volume; $W=$work done

## Isobaric process

p-V graph showing a different thermodynamic processes (1: isothermal, 2: isochoric, 3: isobaric, 4: adiabatic).

In an isobaric process the pressure is kept constant (i.e. $\Delta p=0$). The work done by the gas is given by $p\Delta V$.

The change in internal energy during an isobaric process is given by $\Delta U=Q-p\Delta V$.

The p-V graph of an isobaric process is a horizontal line.

$p=$pressure; $Q=$heat supplied; $T=$temperature; $\Delta U=$change in internal energy; $V=$volume; $W=$work done

## Isothermal process

p-V graph showing an different thermodynamic processes (1: isothermal, 2: isochoric, 3: isobaric, 4: adiabatic).

In an isothermal process, the temperature is kept constant (i.e. $\Delta T=0$). However, there may be heat exchanged between the system and its surroundings (i.e. $Q$ is not necessarily $0$).

The p-V graph of an isothermal process is a curve. The p-V curve of an isothermal process is gentler than that of an adiabatic process.

$p=$pressure; $Q=$heat supplied; $T=$temperature; $\Delta U=$change in internal energy; $V=$volume; $W=$work done

p-V graph showing an different thermodynamic processes (1: isothermal, 2: isochoric, 3: isobaric, 4: adiabatic).

In an adiabatic process there is no transfer of heat between the system and its surroundings (i.e. $Q=0$). However, the temperature may not be constant (i.e. $\Delta T$ is not necessarily $0$).

The change in internal energy during an adiabatic process is equal to the work done on the system (i.e. $\Delta U=W$).

The p-V graph of an adiabatic process is a curve. The p-V curve of an adiabatic process is steeper than that of an isothermal process.

$p=$pressure; $Q=$heat supplied; $T=$temperature; $\Delta U=$change in internal energy; $V=$volume; $W=$work done

## Summary of thermodynamic processes

Process Characteristics
Isochoric $\Delta V=0$; $W=0$; $\Delta U=Q$
Isobaric $\Delta p=0$; $W=p\Delta V$; $\Delta U=Q-p\Delta V$
Isothermal $\Delta T=0$
Adiabatic $Q=0$; $\Delta U=W$

Thermodynamic processes are not necessarily distinct from each other.

It is possible for a thermodynamic process to be both adiabatic and isobaric ($Q=0$ and $\Delta p=0$), or adiabatic and isothermal ($Q=0$ and $\Delta T=0$).

$p=$pressure; $Q=$heat supplied; $T=$temperature; $\Delta U=$change in internal energy; $V=$volume; $W=$work done

p-V graph showing an different thermodynamic processes (1: isothermal, 2: isochoric, 3: isobaric, 4: adiabatic).


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# Show that a function is monotone and its set of discontinuities is equal to a sequence.

Let $$(a_n)_{n\geq 1}$$ be a sequence with $$a_n \in [0,1]$$ for all $$n \geq 1$$.

Show that $$f\colon[0,1]\to [0,1], \quad f(x) = \sum_{\{k : a_k\leq x \}}2^{-k-1}$$

is a monotone function and that the set of its discontinuities is equal to $$(a_n)_{n\geq 1}$$.

I tried around with some sequences and think that the function starts at 0, is monotonically increasing and is constant until x is equal to the next highest element of the sequence and then it jumps to a higher value. But I don't know where to start to prove it, could someone provide me a hint?

Suppose $$x,y \in [0,1]$$ with $$x \leq y$$. Then we clearly have $$\{k : a_k\leq x\} \subseteq \{k : a_k \leq y\}$$. This means $$\sum_{\{k : a_k\leq x \}}2^{-k-1}\leq \sum_{\{k : a_k\leq y \}}2^{-k-1}$$, and so $$f(x) \leq f(y)$$.
As for the set of discontinuities your intuition seems on the right track (except for the "starts at $$0$$" bit) but unless we change how either the sequence or function are defined, we can merely say that the set of discontinuities of $$f$$ is contained in the range of the sequence $$\{a_n\}_{n=1}^\infty$$. Why? Consider the problem as if $$\{a_n\}_{n=1}^\infty$$ has no nonzero term or even just a finite number of nonzero terms.
• for instance if the sequence $\{a_n\}_{n=1}^\infty$ has no nonzero term, then $f \equiv \frac12$. – Matt A Pelto Jan 22 at 19:12


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# How do you graph y=-2sinpix and include two full periods?

May 18, 2018

See the explanation:

#### Explanation:

First, find the amplitude and the period and phase shifting:

$a \sin b x + c$
amplitude: $| a |$
period: for sine its period is $2 \pi$ so $\frac{2 \pi}{b}$
phase shift: $- c$

So

amplitude = $| - 2 | = 2$

period = $\frac{2 \pi}{\pi} = 2$

fourth period: $\frac{2}{4} = \frac{1}{2}$

phase shifting = no phase shifting.((starts at 0)) origin

for myself to graph $\sin$ or $\cos$ I use a method that I take fouth the period and add it to the phase shift to go to the right and to the left by subtracting

"""one thing you have to keep in your mind which is the standard graph of $\sin$"""

$- 2 \sin \pi x$

it is negative so it starts at the origin and goes down if it is positive it will go up

so first point you plot at the origin then move fourth period to the right by adding $0 + \frac{1}{2}$

first point at the origin
$\left(0 , 0\right)$

to the right:

$\left(\frac{1}{2} , - 2\right)$ go down

$\left(1 , 0\right)$ back to average

$\left(\frac{3}{2} , 2\right)$go up

$\left(2 , 0\right)$back to average

"this is a full period"

to the left by back to the origin and subtract fourth period:
$\left(0 , 0\right)$ at average

$\left(- \frac{1}{2} , 2\right)$ go up

$\left(- 1 , 0\right)$ back to average

$\left(- \frac{3}{2} , - 2\right)$ go down

$\left(- 2 , 0\right)$ back to average

plot and connect the points

these are two full periods a period at the right of the y-axis and a period to the left of the y-axis you could make them both at the right or both at the left.

graph{-2*sin(pix) [-4.93, 4.935, -2.113, 2.82]}


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# Spin cycle of a washing machine

During the spin cycle of a washing machine, the clothes stick to the outer wall of the barrel as it spins at a rate as high as $$1800$$ revolutions per minute. The radius of the barrel is $$26 \text{ cm.}$$ Determine the approximate speed of the clothes (in m/s) which are located on the outer wall of the spinning barrel.

×

Problem Loading...

Note Loading...

Set Loading...


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# Gecko XP2 Pump Suction Cover 91231606

Item #: 91231606

### Item Details

Gecko XP2 Pump Suction Cover 91231606

Suction Cover/Face Plate for the following Gecko Pumps:
• Gecko Flo-Master XP2 Pumps
Gecko 91231606

## Customer Reviews

Based on 1 review
100%
(1)
0%
(0)
0%
(0)
0%
(0)
0%
(0)
C
Chuck S.
Pump

Fit just right. Also called to figure out the oring gasket for the pump. They referred me to the manufacturer and gave me the number. About 2 minutes into the call I had the part number and had it ordered. Thanks guys!

## Customer Reviews

Based on 1 review
100%
(1)
0%
(0)
0%
(0)
0%
(0)
0%
(0)
C
Chuck S.
Pump

Fit just right. Also called to figure out the oring gasket for the pump. They referred me to the manufacturer and gave me the number. About 2 minutes into the call I had the part number and had it ordered. Thanks guys!


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The peak wavelength and total radiated amount vary with temperature according to Wien's displacement law. Although this shows relatively high temperatures, the same relationships hold true for any temperature down to absolute zero.
Thermal radiation in visible light can be seen on this hot metalwork. Its emission in the infrared is invisible to the human eye. Infrared cameras are capable of capturing this infrared emission (see Thermography).

Thermal radiation is electromagnetic radiation generated by the thermal motion of particles in matter. All matter with a temperature greater than absolute zero emits thermal radiation. Particle motion results in charge-acceleration or dipole oscillation which produces electromagnetic radiation.

The infrared radiation emitted by animals that is detectable with an infrared camera, and the cosmic microwave background radiation, are all examples of thermal radiation.

If a radiation object meets the physical characteristics of a black body in thermodynamic equilibrium, the radiation is called blackbody radiation.[1]Planck's law describes the spectrum of blackbody radiation, which depends solely on the object's temperature. Wien's displacement law determines the most likely frequency of the emitted radiation, and the Stefan-Boltzmann law gives the radiant intensity.[2]

Thermal radiation is also one of the fundamental mechanisms of heat transfer.

## Overview

Thermal radiation, also known as heat, is the emission of electromagnetic waves from all matter that has a temperature greater than absolute zero.[3] It represents the conversion of thermal energy into electromagnetic energy. Thermal energy consists of the kinetic energy of random movements of atoms and molecules in matter. All matter with a temperature by definition is composed of particles which have kinetic energy, and which interact with each other. These atoms and molecules are composed of charged particles, i.e., protons and electrons, and kinetic interactions among matter particles result in charge-acceleration and dipole-oscillation. This results in the electrodynamic generation of coupled electric and magnetic fields, resulting in the emission of photons, radiating energy away from the body through its surface boundary. Electromagnetic radiation, including light, does not require the presence of matter to propagate and travels in the vacuum of space infinitely far if unobstructed.

The characteristics of thermal radiation depend on various properties of the surface it is emanating from, including its temperature, its spectral absorptivity and spectral emissive power, as expressed by Kirchhoff's law.[3] The radiation is not monochromatic, i.e., it does not consist of just a single frequency, but comprises a continuous dispersion of photon energies, its characteristic spectrum. If the radiating body and its surface are in thermodynamic equilibrium and the surface has perfect absorptivity at all wavelengths, it is characterized as a black body. A black body is also a perfect emitter. The radiation of such perfect emitters is called black-body radiation. The ratio of any body's emission relative to that of a black body is the body's emissivity, so that a black body has an emissivity of unity.

Spectral response of two paints and a mirrored surface, in the visible and the infrared. From NASA.

Absorptivity, reflectivity, and emissivity of all bodies are dependent on the wavelength of the radiation. Due to reciprocity, absorptivity and emissivity for any particular wavelength are equal - a good absorber is necessarily a good emitter, and a poor absorber a poor emitter. The temperature determines the wavelength distribution of the electromagnetic radiation. For example, the white paint in the diagram to the right is highly reflective to visible light (reflectivity about 0.80), and so appears white to the human eye due to reflecting sunlight, which has a peak wavelength of about 0.5 micrometers. However, its emissivity at a temperature of about -5 °C (23 °F), peak wavelength of about 12 micrometers, is 0.95. Thus, to thermal radiation it appears black.

The distribution of power that a black body emits with varying frequency is described by Planck's law. At any given temperature, there is a frequency fmax at which the power emitted is a maximum. Wien's displacement law, and the fact that the frequency is inversely proportional to the wavelength, indicates that the peak frequency fmax is proportional to the absolute temperature T of the black body. The photosphere of the sun, at a temperature of approximately 6000 K, emits radiation principally in the (humanly) visible portion of the electromagnetic spectrum. Earth's atmosphere is partly transparent to visible light, and the light reaching the surface is absorbed or reflected. Earth's surface emits the absorbed radiation, approximating the behavior of a black body at 300 K with spectral peak at fmax. At these lower frequencies, the atmosphere is largely opaque and radiation from Earth's surface is absorbed or scattered by the atmosphere. Though about 10% of this radiation escapes into space, most is absorbed and then re-emitted by atmospheric gases. It is this spectral selectivity of the atmosphere that is responsible for the planetary greenhouse effect, contributing to global warming and climate change in general (but also critically contributing to climate stability when the composition and properties of the atmosphere are not changing).

The incandescent light bulb has a spectrum overlapping the black body spectra of the sun and the earth. Some of the photons emitted by a tungsten light bulb filament at 3000 K are in the visible spectrum. Most of the energy is associated with photons of longer wavelengths; these do not help a person see, but still transfer heat to the environment, as can be deduced empirically by observing an incandescent light bulb. Whenever EM radiation is emitted and then absorbed, heat is transferred. This principle is used in microwave ovens, laser cutting, and RF hair removal.

Unlike conductive and convective forms of heat transfer, thermal radiation can be concentrated in a tiny spot by using reflecting mirrors. Concentrating solar power takes advantage of this fact. In many such systems, mirrors are employed to concentrate sunlight into a smaller area. Instead of mirrors, Fresnel lenses can also be used to concentrate heat flux. (In principle, any kind of lens can be used, but only the Fresnel lens design is practical for very large lenses.) Either method can be used to quickly vaporize water into steam using sunlight. For example, the sunlight reflected from mirrors heats the PS10 Solar Power Plant, and during the day it can heat water to 285 °C (558.15 K) or 545 °F.

### Surface effects

Lighter colors and also whites and metallic substances absorb less illuminating light, and as a result heat up less; but otherwise color makes small difference as regards heat transfer between an object at everyday temperatures and its surroundings, since the dominant emitted wavelengths are nowhere near the visible spectrum, but rather in the far infrared. Emissivities at those wavelengths have little to do with visual emissivities (visible colors); in the far infra-red, most objects have high emissivities. Thus, except in sunlight, the color of clothing makes little difference as regards warmth; likewise, paint color of houses makes little difference to warmth except when the painted part is sunlit.

The main exception to this is shiny metal surfaces, which have low emissivities both in the visible wavelengths and in the far infrared. Such surfaces can be used to reduce heat transfer in both directions; an example of this is the multi-layer insulation used to insulate spacecraft.

Low-emissivity windows in houses are a more complicated technology, since they must have low emissivity at thermal wavelengths while remaining transparent to visible light.

Nanostructures with spectrally selective thermal emittance properties offer numerous technological applications for energy generation and efficiency,[4] e.g., for cooling photovoltaic cells and buildings. These applications require high emittance in the frequency range corresponding to the atmospheric transparency window in 8 to 13 micron wavelength range. A selective emitter radiating strongly in this range is thus exposed to the clear sky, enabling the use of the outer space as a very low temperature heat sink.[5]

Personalized cooling technology is another example of an application where optical spectral selectivity can be beneficial. Conventional personal cooling is typically achieved through heat conduction and convection. However, the human body is a very efficient emitter of infrared radiation, which provides an additional cooling mechanism. Most conventional fabrics are opaque to infrared radiation and block thermal emission from the body to the environment. Fabrics for personalized cooling applications have been proposed that enable infrared transmission to directly pass through clothing, while being opaque at visible wavelengths. Fabrics that are transparent in the infrared can radiate body heat at rates that will significantly reduce the burden on power-hungry air-conditioning systems.[]

## Properties

There are 4 main properties that characterize thermal radiation (in the limit of the far field):

• Thermal radiation emitted by a body at any temperature consists of a wide range of frequencies. The frequency distribution is given by Planck's law of black-body radiation for an idealized emitter as shown in the diagram at top.
• The dominant frequency (or color) range of the emitted radiation shifts to higher frequencies as the temperature of the emitter increases. For example, a red hot object radiates mainly in the long wavelengths (red and orange) of the visible band. If it is heated further, it also begins to emit discernible amounts of green and blue light, and the spread of frequencies in the entire visible range cause it to appear white to the human eye; it is white hot. Even at a white-hot temperature of 2000 K, 99% of the energy of the radiation is still in the infrared. This is determined by Wien's displacement law. In the diagram the peak value for each curve moves to the left as the temperature increases.
• The total amount of radiation of all frequency increases steeply as the temperature rises; it grows as T4, where T is the absolute temperature of the body. An object at the temperature of a kitchen oven, about twice the room temperature on the absolute temperature scale (600 K vs. 300 K) radiates 14 times as much power per unit area. An object at the temperature of the filament in an incandescent light bulb--roughly 3000 K, or 10 times room temperature--radiates 10,000 times as much energy per unit area. The total radiative intensity of a black body rises as the fourth power of the absolute temperature, as expressed by the Stefan-Boltzmann law. In the plot, the area under each curve grows rapidly as the temperature increases.
• The rate of electromagnetic radiation emitted at a given frequency is proportional to the amount of absorption that it would experience by the source, a property known as reciprocity. Thus, a surface that absorbs more red light thermally radiates more red light. This principle applies to all properties of the wave, including wavelength (color), direction, polarization, and even coherence, so that it is quite possible to have thermal radiation which is polarized, coherent, and directional, though polarized and coherent forms are fairly rare in nature far from sources (in terms of wavelength). See section below for more on this qualification.

### Near-field and far-field

The general properties of thermal radiation as described by the Planck's law apply if the linear dimension of all parts considered, as well as radii of curvature of all surfaces are large compared with the wavelength of the ray considered' (typically from 8-25 micrometres for the emitter at 300 K). Indeed, thermal radiation as discussed above takes only radiating waves (far-field, or electromagnetic radiation) into account. A more sophisticated framework involving electromagnetic theory must be used for smaller distances from the thermal source or surface (near-field thermal radiation). For example, although far-field thermal radiation at distances from surfaces of more than one wavelength is generally not coherent to any extent, near-field thermal radiation (i.e., radiation at distances of a fraction of various radiation wavelengths) may exhibit a degree of both temporal and spatial coherence.[6]

Planck's law of thermal radiation has been challenged in recent decades by predictions and successful demonstrations of the radiative heat transfer between objects separated by nanoscale gaps that deviate significantly from the law predictions. This deviation is especially strong (up to several orders in magnitude) when the emitter and absorber support surface polariton modes that can couple through the gap separating cold and hot objects. However, to take advantage of the surface-polariton-mediated near-field radiative heat transfer, the two objects need to be separated by ultra-narrow gaps on the order of microns or even nanometers. This limitation significantly complicates practical device designs.

Another way to modify the object thermal emission spectrum is by reducing the dimensionality of the emitter itself.[4] This approach builds upon the concept of confining electrons in quantum wells, wires and dots, and tailors thermal emission by engineering confined photon states in two- and three-dimensional potential traps, including wells, wires, and dots. Such spatial confinement concentrates photon states and enhances thermal emission at select frequencies.[7] To achieve the required level of photon confinement, the dimensions of the radiating objects should be on the order of or below the thermal wavelength predicted by Planck's law. Most importantly, the emission spectrum of thermal wells, wires and dots deviates from Planck's law predictions not only in the near field, but also in the far field, which significantly expands the range of their applications.

### Subjective color to the eye of a black body thermal radiator

°C (°F) Subjective color[8]
480 °C (896 °F) faint red glow
580 °C (1,076 °F) dark red
730 °C (1,350 °F) bright red, slightly orange
930 °C (1,710 °F) bright orange
1,100 °C (2,010 °F) pale yellowish orange
1,300 °C (2,370 °F) yellowish white
> 1,400 °C (2,550 °F) white (yellowish if seen from a distance through atmosphere)

The time to a damage from exposure to radiative heat is a function of the rate of delivery of the heat.[9] Radiative heat flux and effects:[10] (1 W/cm2 = 10 kW/m2)

kW/m2 Effect
170 Maximum flux measured in a post-flashover compartment
80 Thermal Protective Performance test for personal protective equipment
52 Fiberboard ignites at 5 seconds
29 Wood ignites, given time
20 Typical beginning of flashover at floor level of a residential room
16 Human skin: sudden pain and second-degree burn blisters after 5 seconds
12.5 Wood produces ignitable volatiles by pyrolysis
10.4 Human skin: Pain after 3 seconds, second-degree burn blisters after 9 seconds
6.4 Human skin: second-degree burn blisters after 18 seconds
4.5 Human skin: second-degree burn blisters after 30 seconds
2.5 Human skin: burns after prolonged exposure, radiant flux exposure typically encountered during firefighting
1.4 Sunlight, sunburns potentially within 30 minutes. Sunburn is NOT a thermal burn. It is caused by DNA damage due to ultraviolet radiation.

## Interchange of energy

Radiant heat panel for testing precisely quantified energy exposures at National Research Council, near Ottawa, Ontario, Canada

Thermal radiation is one of the three principal mechanisms of heat transfer. It entails the emission of a spectrum of electromagnetic radiation due to an object's temperature. Other mechanisms are convection and conduction.

Radiation heat transfer is characteristically different from the other two in that it does not require a medium and, in fact it reaches maximum efficiency in a vacuum. Electromagnetic radiation has some proper characteristics depending on the frequency and wavelengths of the radiation. The phenomenon of radiation is not yet fully understood. Two theories have been used to explain radiation; however neither of them is perfectly satisfactory.

First, the earlier theory which originated from the concept of a hypothetical medium referred as ether. Ether supposedly fills all evacuated or non evacuated spaces. The transmission of light or of radiant heat are allowed by the propagation of electromagnetic waves in the ether.[11] Electromagnetic waves have similar characteristics to television and radio broadcasting waves they only differ in wavelength.[12] All electromagnetic waves travel at the same speed; therefore, shorter wavelengths are associated with high frequencies. Since every body or fluid is submerged in the ether, due to the vibration of the molecules, any body or fluid can potentially initiate an electromagnetic wave. All bodies generate and receive electromagnetic waves at the expense of its stored energy [12]

The second theory of radiation is best known as the quantum theory and was first offered by Max Planck in 1900.[11] According to this theory, energy emitted by a radiator is not continuous but is in the form of quanta. Planck claimed that quantities had different sizes and frequencies of vibration similarly to the wave theory.[13] The energy E is found by the expression E = h?, where h is the Planck's constant and ? is the frequency. Higher frequencies are originated by high temperatures and create an increase of energy in the quantum. While the propagation of electromagnetic waves of all wavelengths is often referred as "radiation," thermal radiation is often constrained to the visible and infrared regions. For engineering purposes, it may be stated that thermal radiation is a form of electromagnetic radiation which varies on the nature of a surface and its temperature.[11] Radiation waves may travel in unusual patterns compared to conduction heat flow. Radiation allows waves to travel from a heated body through a cold nonabsorbing or partially absorbing medium and reach a warmer body again.[11] This is the case of the radiation waves that travel from the sun to the earth.

The interplay of energy exchange by thermal radiation is characterized by the following equation:

${\displaystyle \alpha +\rho +\tau =1.\,}$

Here, ${\displaystyle \alpha \,}$ represents the spectral absorption component, ${\displaystyle \rho \,}$ spectral reflection component and ${\displaystyle \tau \,}$ the spectral transmission component. These elements are a function of the wavelength (${\displaystyle \lambda \,}$) of the electromagnetic radiation. The spectral absorption is equal to the emissivity ${\displaystyle \epsilon \,}$; this relation is known as Kirchhoff's law of thermal radiation. An object is called a black body if, for all frequencies, the following formula applies:

${\displaystyle \alpha =\epsilon =1.\,}$

Reflectivity deviates from the other properties in that it is bidirectional in nature. In other words, this property depends on the direction of the incident of radiation as well as the direction of the reflection. Therefore, the reflected rays of a radiation spectrum incident on a real surface in a specified direction forms an irregular shape that is not easily predictable. In practice, surfaces are assumed to reflect in a perfectly specular or diffuse manner. In a specular reflection, the angles of reflection and incidence are equal. In diffuse reflection, radiation is reflected equally in all directions. Reflection from smooth and polished surfaces can be assumed to be specular reflection, whereas reflection from rough surfaces approximates diffuse reflection.[14] In radiation analysis a surface is defined as smooth if the height of the surface roughness is much smaller relative to the wavelength of the incident radiation.

In a practical situation and room-temperature setting, humans lose considerable energy due to thermal radiation in infra-red in addition to that lost by conduction to air (aided by concurrent convection, or other air movement like drafts). The heat energy lost is partially regained by absorbing heat radiation from walls or other surroundings. (Heat gained by conduction would occur for air temperature higher than body temperature.) Otherwise, body temperature is maintained from generated heat through internal metabolism. Human skin has an emissivity of very close to 1.0.[15] Using the formulas below shows a human, having roughly in surface area, and a temperature of about 307 K, continuously radiates approximately 1000 watts. If people are indoors, surrounded by surfaces at 296 K, they receive back about 900 watts from the wall, ceiling, and other surroundings, so the net loss is only about 100 watts. These heat transfer estimates are highly dependent on extrinsic variables, such as wearing clothes, i.e. decreasing total thermal circuit conductivity, therefore reducing total output heat flux. Only truly gray systems (relative equivalent emissivity/absorptivity and no directional transmissivity dependence in all control volume bodies considered) can achieve reasonable steady-state heat flux estimates through the Stefan-Boltzmann law. Encountering this "ideally calculable" situation is almost impossible (although common engineering procedures surrender the dependency of these unknown variables and "assume" this to be the case). Optimistically, these "gray" approximations will get close to real solutions, as most divergence from Stefan-Boltzmann solutions is very small (especially in most STP lab controlled environments).

Spectral response of two paints and a mirrored surface, in the visible and the infrared. From NASA.

If objects appear white (reflective in the visual spectrum), they are not necessarily equally reflective (and thus non-emissive) in the thermal infrared - see the diagram at the left. Most household radiators are painted white, which is sensible given that they are not hot enough to radiate any significant amount of heat, and are not designed as thermal radiators at all - instead, they are actually convectors, and painting them matt black would make little difference to their efficacy. Acrylic and urethane based white paints have 93% blackbody radiation efficiency at room temperature[16] (meaning the term "black body" does not always correspond to the visually perceived color of an object). These materials that do not follow the "black color = high emissivity/absorptivity" caveat will most likely have functional spectral emissivity/absorptivity dependence.

Calculation of radiative heat transfer between groups of object, including a 'cavity' or 'surroundings' requires solution of a set of simultaneous equations using the radiosity method. In these calculations, the geometrical configuration of the problem is distilled to a set of numbers called view factors, which give the proportion of radiation leaving any given surface that hits another specific surface. These calculations are important in the fields of solar thermal energy, boiler and furnace design and raytraced computer graphics.

A comparison of a thermal image (top) and an ordinary photograph (bottom) shows that a trash bag is transparent, but glass (the man's spectacles) is opaque in long-wavelength infrared.

To reduce the heat transfer from a surface, such as a glass window, a clear reflective film with a low emissivity coating can be placed on the interior of the surface. "Low-emittance (low-E) coatings are microscopically thin, virtually invisible, metal or metallic oxide layers deposited on a window or skylight glazing surface primarily to reduce the U-factor by suppressing radiative heat flow".[19] By adding this coating we are limiting the amount of radiation that leaves the window thus increasing the amount of heat that is retained inside the window.

Since any electromagnetic radiation, including thermal radiation, conveys momentum as well as energy, thermal radiation also induces very small forces on the radiating or absorbing objects. Normally these forces are negligible, but they must be taken into account when considering spacecraft navigation. The Pioneer anomaly, where the motion of the craft slightly deviated from that expected from gravity alone, was eventually tracked down to asymmetric thermal radiation from the spacecraft. Similarly, the orbits of asteroids are perturbed since the asteroid absorbs solar radiation on the side facing the sun, but then re-emits the energy at a different angle as the rotation of the asteroid carries the warm surface out of the sun's view (the YORP effect).

Power emitted by a black body plotted against the temperature according to the Stefan-Boltzmann law.

Thermal radiation power of a black body per unit area of radiating surface per unit of solid angle and per unit frequency ${\displaystyle \nu }$ is given by Planck's law as:

${\displaystyle u(\nu ,T)={\frac {2h\nu ^{3}}{c^{2}}}\cdot {\frac {1}{e^{h\nu /k_{B}T}-1}}}$

or instead of per unit frequency, per unit wavelength as

${\displaystyle u(\lambda ,T)={\frac {2hc^{2}}{\lambda ^{5}}}\cdot {\frac {1}{e^{hc/k_{B}T\lambda }-1}}}$

This formula mathematically follows from calculation of spectral distribution of energy in quantized electromagnetic field which is in complete thermal equilibrium with the radiating object. Plancks law shows that radiative energy increases with temperature, and explains why the peak of an emission spectrum shifts to shorter wavelengths at higher temperatures. It can also be found that energy emitted at shorter wavelengths increases more rapidly with temperature relative to longer wavelengths.[20] The equation is derived as an infinite sum over all possible frequencies in a semi-sphere region. The energy, ${\displaystyle E=h\nu }$, of each photon is multiplied by the number of states available at that frequency, and the probability that each of those states will be occupied.

Integrating the above equation over ${\displaystyle \nu }$ the power output given by the Stefan-Boltzmann law is obtained, as:

${\displaystyle P=\sigma \cdot A\cdot T^{4}}$

where the constant of proportionality ${\displaystyle \sigma }$ is the Stefan-Boltzmann constant and ${\displaystyle A}$ is the radiating surface area.

The wavelength ${\displaystyle \lambda \,}$, for which the emission intensity is highest, is given by Wien's displacement law as:

${\displaystyle \lambda _{\text{max}}={\frac {b}{T}}}$

For surfaces which are not black bodies, one has to consider the (generally frequency dependent) emissivity factor ${\displaystyle \epsilon (\nu )}$. This factor has to be multiplied with the radiation spectrum formula before integration. If it is taken as a constant, the resulting formula for the power output can be written in a way that contains ${\displaystyle \epsilon }$ as a factor:

${\displaystyle P=\epsilon \cdot \sigma \cdot A\cdot T^{4}}$

This type of theoretical model, with frequency-independent emissivity lower than that of a perfect black body, is often known as a grey body. For frequency-dependent emissivity, the solution for the integrated power depends on the functional form of the dependence, though in general there is no simple expression for it. Practically speaking, if the emissivity of the body is roughly constant around the peak emission wavelength, the gray body model tends to work fairly well since the weight of the curve around the peak emission tends to dominate the integral.

### Constants

Definitions of constants used in the above equations:

 ${\displaystyle h\,}$ Planck's constant 6.626 069 3(11)×10-34 J·s = 4.135 667 43(35)×10-15 eV·s ${\displaystyle b\,}$ Wien's displacement constant 2.897 768 5(51)×10-3 m·K ${\displaystyle k_{B}\,}$ Boltzmann constant 1.380 650 5(24)×10-23 J·K-1 = 8.617 343 (15)×10-5 eV·K-1 ${\displaystyle \sigma \,}$ Stefan-Boltzmann constant 5.670 373 (21)×10-8 W·m-2·K-4 ${\displaystyle c\,}$ Speed of light 299 792 458 m·s-1

### Variables

Definitions of variables, with example values:

 ${\displaystyle T}$ Absolute temperature For units used above, must be in kelvins (e.g. average surface temperature on Earth = 288 K) ${\displaystyle A}$ Surface area Acuboid = 2ab + 2bc + 2ac;Acylinder = 2?·r(h + r);Asphere = 4?·r2

The net radiative heat transfer from one surface to another is the radiation leaving the first surface for the other minus that arriving from the second surface.

• For black bodies, the rate of energy transfer from surface 1 to surface 2 is:
${\displaystyle {\dot {Q}}_{1\rightarrow 2}=A_{1}E_{b1}F_{1\rightarrow 2}-A_{2}E_{b2}F_{2\rightarrow 1}}$

where ${\displaystyle A}$ is surface area, ${\displaystyle E_{b}}$ is energy flux (the rate of emission per unit surface area) and ${\displaystyle F_{1\rightarrow 2}}$ is the view factor from surface 1 to surface 2. Applying both the reciprocity rule for view factors, ${\displaystyle A_{1}F_{1\rightarrow 2}=A_{2}F_{2\rightarrow 1}}$, and the Stefan-Boltzmann law, ${\displaystyle E_{b}=\sigma T^{4}}$, yields:

${\displaystyle {\dot {Q}}_{1\rightarrow 2}=\sigma A_{1}F_{1\rightarrow 2}(T_{1}^{4}-T_{2}^{4})\!}$

where ${\displaystyle \sigma }$ is the Stefan-Boltzmann constant and ${\displaystyle T}$ is temperature.[17] A negative value for ${\displaystyle {\dot {Q}}}$ indicates that net radiation heat transfer is from surface 2 to surface 1.

• For two grey-body surfaces forming an enclosure, the heat transfer rate is:
${\displaystyle {\dot {Q}}={\dfrac {\sigma (T_{1}^{4}-T_{2}^{4})}{{\dfrac {1-\epsilon _{1}}{A_{1}\epsilon _{1}}}+{\dfrac {1}{A_{1}F_{1\rightarrow 2}}}+{\dfrac {1-\epsilon _{2}}{A_{2}\epsilon _{2}}}}}}$

where ${\displaystyle \epsilon _{1}}$ and ${\displaystyle \epsilon _{2}}$ are the emissivities of the surfaces.[17]

Formulas for radiative heat transfer can be derived for more particular or more elaborate physical arrangements, such as between parallel plates, concentric spheres and the internal surfaces of a cylinder.[17]

## References

1. ^ K. Huang, Statistical Mechanics (2003), p.278
2. ^ K. Huang, Statistical Mechanics (2003), p.280
3. ^ a b S. Blundell, K. Blundell (2006). Concepts in Thermal Physics. Oxford University Press. p. 247. ISBN 978-0-19-856769-1.
4. ^ a b Fan, Shanhui; Li, Wei (11 June 2018). "Nanophotonic control of thermal radiation for energy applications [Invited]". Optics Express. 26 (12): 15995-16021. doi:10.1364/OE.26.015995. ISSN 1094-4087.
5. ^ Zhai, Yao; Ma, Yaoguang; David, Sabrina N.; Zhao, Dongliang; Lou, Runnan; Tan, Gang; Yang, Ronggui; Yin, Xiaobo (10 March 2017). "Scalable-manufactured randomized glass-polymer hybrid metamaterial for daytime radiative cooling". Science. 355 (6329): 1062-1066. Bibcode:2017Sci...355.1062Z. doi:10.1126/science.aai7899. ISSN 0036-8075. PMID 28183998.
6. ^ Greffet, Jean-Jacques; Henkel, Carsten (2007). "Coherent thermal radiation". Contemporary Physics. 48 (4): 183-194. Bibcode:2007ConPh..48..183G. doi:10.1080/00107510701690380.
7. ^ Rephaeli, Eden; Raman, Aaswath; Fan, Shanhui (2013). "Ultrabroadband photonic structures to achieve high-performance daytime radiative cooling". Nano Letters. 13 (4): 1457-1461. Bibcode:2013NanoL..13.1457R. doi:10.1021/nl4004283. PMID 23461597.
8. ^ "Wayback Machine". 21 July 2011. Archived from the original on 21 July 2011.
9. ^ Furtak, M.; Silecky, L. (2012). "Evaluation of Onset to Second Degree Burn Energy in Arc Flash, IAEI".
10. ^ John J. Lentini - Scientific Protocols for Fire Investigation, CRC 2006, ISBN 0849320828, table from NFPA 921, Guide for Fire and Explosion Investigations
11. ^ a b c d Hsu, Shao Ti. Engineering Heat Transfer. Blacksburg, Virginia:D. Van Nostrand Company, Inc.,1962.
12. ^ a b Becker, Martin. Heat Transfer a Modern Approach New York: Plenum Publishing Corporation, 1986.
13. ^ Yunus, Cengel. Heat and Mass Transfer.New York: Mc Graw Hill, 2007.
14. ^ Hsu, Shao Ti. Engineering Heat Transfer. Blacksburg, Virginia:D. Van Nostrand Company, Inc.,1962.
15. ^ R. Bowling Barnes (24 May 1963). "Thermography of the Human Body Infrared-radiant energy provides new concepts and instrumentation for medical diagnosis". Science. 140 (3569): 870-877. Bibcode:1963Sci...140..870B. doi:10.1126/science.140.3569.870. PMID 13969373.
16. ^ S. Tanemura, M. Tazawa, P. Jing, T. Miki, K. Yoshimura, K. Igarashi, M. Ohishi, K. Shimono, M. Adachi. "Optical Properties and Radiative Cooling Power of White Paints" (PDF). Archived from the original (PDF) on 2 January 2007. Retrieved 2010. ISES 1999 Solar World Congress
17. ^ a b c d Heat and Mass Transfer, Yunus A. Cengel and Afshin J. Ghajar, 4th Edition
18. ^ Infrared#Different regions in the infrared Short-wavelength infrared is 1.4-3?m, mid-wavelength infrared is 3-8?m
19. ^ The Efficient Windows Collaborative: Window Technologies Archived 26 April 2011 at the Wayback Machine
20. ^ Shao, Gaofeng; et al. (2019). "Improved oxidation resistance of high emissivity coatings on fibrous ceramic for reusable space systems". Corrosion Science. 146: 233-246. doi:10.1016/j.corsci.2018.11.006.


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This option is only enabled when the user has set up several Sphere within the Output - Observation Points section. It plots the near field for each observation spheres in the desired direction versus the radius. After clicking on Show Results - Near Field - View Radial Points, the next window is open.

Within this window, the following options are available:

• Incidence The near field may be plotted by considering different contributions on the observation points.
• Scatter Scattered field components.
• Direct Direct field components.
• Total Combination of the scattered field plus the direct field components.
• Magnitude The near field may be represented in natural or dBs magnitudes.
• dBs The near field is represented in logarithmic scale, given in dB-Amperes per meter for the magnetic field, or in dB-Volts per meter for the electric field.
• nat The near field is represented in natural scale, given in Amperes per meter for the magnetic field, or in Volts per meter for the electric field.
• Component To specify the field component to the plot. Only one component may be selected:
• Ex Plot the X component of the electric field.
• Ey Plot the Y component of the electric field.
• Ez Plot the Z component of the electric field.
• ETotal Plot the total electric field, which is the combination of the X, Y and Z components.
• Hx Plot the X component of magnetic field.
• Hy Plot the Y component of magnetic field.
• Hz Plot the Z component of magnetic field.
• HTotal Plot the total magnetic field, which is the combination of the X, Y and Z components.
• Step, Frequency, Observation and Coords Select the observation points to plot.
• Step To specify the step results files when a parametric simulation has been run.
• Frequency To specify the desired frequency results files when a frequency sweep has been run.
• Observation Spheres List with all the different observation spheres entities that have been defined. Select the desired one to specify the direction in the next fields.
• Theta Cut Spherical theta angle within the above-selected observation sphere, in degrees.
• Phi Cut Spherical theta angle within the above-selected observation sphere, in degrees.
• Add series Confirm the observation points to plot and add its curve.
• Options Having inserted several plots, the Options section allow to edit the result curves:
• List of Series All the plotted field components are listed. Note that two options are included for every plot for most of the components both the amplitude and the phase. However, ETotal and HTotal only represent the module.
• View points Enable this option to visualize the points where the field has been computed for every inserted plot.
• Change color This option allows to change the color of the selected curve in the above List of Series.
• Remove To delete the selected curve in the above List of Series.
• Import Series To add a new plot from an external file. The file must have ". txt" extension, and it must contain in every new line the point index and the values to be plotted.
• Export Series To export the selected curve in the above Plot List in a ".txt" file, with the point index and the value of the plot in a new line.
• Options Disable this option to hide the left menu and visualize just the near field curves.


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# How do you factor 125x^6 - y^6?

##### 1 Answer
Aug 26, 2016

$125 {x}^{6} - {y}^{6} = \left(\sqrt{5} x - y\right) \left(5 {x}^{2} + \sqrt{5} x y + {y}^{2}\right) \left(\sqrt{5} x + y\right) \left(5 {x}^{2} - \sqrt{5} x y + {y}^{2}\right)$

#### Explanation:

The difference of squares identity can be written:

${a}^{2} - {b}^{2} = \left(a - b\right) \left(a + b\right)$

The difference of cubes identity can be written:

${a}^{3} - {b}^{3} = \left(a - b\right) \left({a}^{2} + a b + {b}^{2}\right)$

The sum of cubes identity can be written:

${a}^{3} + {b}^{3} = \left(a + b\right) \left({a}^{2} - a b + {b}^{2}\right)$

Hence we find:

$125 {x}^{6} - {y}^{6}$

$= {\left(\sqrt{125} {x}^{3}\right)}^{2} - {\left({y}^{3}\right)}^{2}$

$= \left(\sqrt{125} {x}^{3} - {y}^{3}\right) \left(\sqrt{125} {x}^{3} + {y}^{3}\right)$

$= \left({\left(\sqrt{5} x\right)}^{3} - {y}^{3}\right) \left({\left(\sqrt{5} x\right)}^{3} + {y}^{3}\right)$

$= \left(\sqrt{5} x - y\right) \left({\left(\sqrt{5} x\right)}^{2} + \left(\sqrt{5} x\right) y + {y}^{2}\right) \left(\sqrt{5} x + y\right) \left({\left(\sqrt{5} x\right)}^{2} - \left(\sqrt{5} x\right) y + {y}^{2}\right)$

$= \left(\sqrt{5} x - y\right) \left(5 {x}^{2} + \sqrt{5} x y + {y}^{2}\right) \left(\sqrt{5} x + y\right) \left(5 {x}^{2} - \sqrt{5} x y + {y}^{2}\right)$

There are no simpler factors with Real coefficients.

If you allow Complex coefficients then you can factor this further as:

$= \left(\sqrt{5} x - y\right) \left(\sqrt{5} x - \omega y\right) \left(\sqrt{5} x - {\omega}^{2} y\right) \left(\sqrt{5} x + y\right) \left(\sqrt{5} x + \omega y\right) \left(\sqrt{5} x + {\omega}^{2} y\right)$

where $\omega = - \frac{1}{2} + \frac{\sqrt{3}}{2} i$ is the primitive Complex cube root of $1$.


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# Getting started with rc_visard and OpenCV¶

This tutorial shows how to get started with the rc_visard and OpenCV. We will show how to receive image streams from the rc_visard with OpenCV via Roboception’s GenICam Convenience Layer rc_genicam_api.

## Before we start¶

Before going through this tutorial, the following prerequisites should be met.

The rc_visard is up and running:

1. The rc_visard is running and connected properly to a network or directly to a computer. One can verify that with our discovery tool.
2. One should know the serial number or user defined name of the rc_visard. The serial number is of the format 029xxxxx. It will be referred to as rc_visard_id in the remainder of this tutorial.

Download and install the following required client software:

1. Install rc_genicam_api. The minimum required version is 2.0.

2. Install OpenCV. The minimum required version is 2.0.

For Ubuntu, installation can be done from the terminal with:

apt install libopencv-dev

3. Install cmake. The minimum required version is 2.8.12.

For Ubuntu, installation can be done from the terminal with:

apt install cmake

1. Download rc_genicam_api

2. Install OpenCV. The minimum required version is 2.0.

Pre-built binaries can be downloaded here.

3. Install cmake. The minimum required version is 2.8.12.

4. Install Microsoft Visual Studio-IDE

## Compiling the example program¶

We provide an example program which shows how to receive image streams from the rc_visard using rc_genicam_api and how to convert them to an OpenCV representation. The example can be downloaded from our GitHub repository.

To successfully compile the program, above prerequisites should be met.

After downloading or cloning the repository, change into the repository’s directory. In a terminal, run the following commands:

mkdir build    # make a build directory
cd build       # change to that directory
cmake ..       # run cmake to configure the build
make           # build the example

1. Create a folder build in the repository.
2. Run CMake (cmake-gui)
3. In cmake, set the source code location to the repository folder
4. Set the binaries location to the just created build folder
5. Click Configure
6. A pop-up will open, asking for the generator
7. Choose the installed version of Visual Studio
8. Click finish
9. Wait until configuration is finished
10. Most likely, an error about not finding OpenCV will occur
1. Set OpenCV_DIR to the subfolder build\x64\vc15\lib of the OpenCV installation path
2. Again, click Configure
11. Most likely, an error about not finding rc_genicam_api will occur
1. Set RC_GENICAM_API_DIR to the subfolder lib\rc_genicam_api of the rc_genicam_api installation path
2. Again, click Configure
12. Set CMAKE_INSTALL_PREFIX to the folder where the example is installed (e.g. install in the repository)
13. Click Generate
14. Click Open Project. Microsoft Visual Studio-IDE will open
15. In Visual Studio, right-click on ALL_BUILD and choose Build
16. Right-click on INSTALL and choose Build

The build will yield a shared library (rc_visard_opencv_example) and an executable (rc_visard_show_streams), which uses the shared library.

## Running the example program¶

The example executable rc_visard_show_streams shows live image streams in an OpenCV window. One can specify which streams to enable by setting command line options.

In case above build instructions were used, one should first change to the tools directory in build before running the program:

cd tools

To run the program, the general syntax is:

./rc_visard_show_streams [options] <rc_visard_id>

In the following we assume that above build instructions were followed and that the example program was installed into install in the repository folder.

1. Open the install folder

2. In the address bar of the Windows Explorer window, type cmd to open a command line window

3. To run the program, use the following command

rc_visard_show_streams.exe [options] <rc_visard_id>

Note

The PATH environment variable should be set to the appropriate folders containing the OpenCV and rc_genicam_api DLLs. Otherwise, an error will occur when running rc_visard_show_streams.

<rc_visard_id> is to be replaced by the rc_visard serial number, GenTL ID or user defined ID.

[options] can be

• --left: connect to the left image stream
• --right: connect to the right image stream
• --disparity: connect to the disparity image stream
• --confidence: connect to the confidence image stream
• --error: connect to the error image stream
• --synchronize: synchronize the received images by their timestamp

For example, to show the left and right image, run:

./rc_visard_show_streams --left --right <rc_visard_id>

rc_visard_show_streams.exe --left --right <rc_visard_id>

While the program is running, press n (next), p (previous) to cycle through the enabled image streams. Press q to exit the program.

## Explanation of the example’s source code¶

The example is documented using Doxygen. To generate the source code documentation, perform the following steps:

In the build directory, run:

make doc

Afterwards, open index.html in doc/html.

1. Install Doxygen
2. In the cmake-gui, click on Configure and then Generate
3. Click on Open Project
4. In Microsoft Visual Studio-IDE, right-click on doc and choose BUILD
5. Go to the build\doc\html subfolder of the repository
6. Open index.html

### Project structure¶

Fig. 9 Dependency diagram

The example consists of a shared library rc_visard_opencv_example and an executable rc_visard_show_streams. The library is designed to make it easy to reuse it for other projects that require OpenCV images. Below, the library will be described in more detail.

Both the library and the executable depend on OpenCV. rc_genicam_api is hidden by the shared library rc_visard_opencv_example.

### Library structure¶

Fig. 10 Simplified class diagram

The core class of rc_visard_opencv_example is GcReceiver. It wraps rc_genicam_api, takes care of bootstrapping and shutting down the connection to the rc_visard, and delegates decoding of image streams to the appropriate ImageReceiver.

ImageReceiver is an abstract base class of the concrete classes IntensityReceiver, DisparityReceiver, ConfidenceReceiver and ErrorReceiver, each of which is responsible for receiving one kind of image stream. Each concrete ImageReceiver implements a) enabling of the image stream from the rc_visard and b) converting the GenICam representation of the image to an OpenCV representation.

The user of the library decides which image streams to enable by passing a list of ImageReceiverFactorys to GcReceiver. For each concrete ImageReceiver there is child class of ImageReceiverFactory, e.g. IntensityReceiverFactory.

To set up streaming of images, the following steps are required:

1. Create a new GcReceiver. Its constructor requires the rc_visard_id.
2. Call GcReceiver::open() to open the connection to the rc_visard.
3. Call GcReceiver::initializeStreams() and pass the list of ImageReceiverFactorys.

After set-up was successful, we can start receiving images. For that, GcReceiver::receive() needs to be called. It grabs the latest image from the GenICam buffer and passes it to each ImageReceiver via its process() method, until one of them takes responsibility for it. The image buffer is then stored in a queue in the ImageReceiver. Afterwards, the image can be extracted from the queue and converted to an OpenCV representation by calling ImageReceiver::grab() and passing the timestamp of the image. This all happens inside GcReceiver::receive(), so the user does not need to care about it. receive() will return an ImageSet with all received images contained.

ImageSet is an aggregation of Images, one for each image type, including left, right, confidence, disparity and error image. Depending on whether synchronization is enabled (see command line options), the returned ImageSet either contains a complete set of synchronized images or only the one image that was just received.

### Enabling image streams¶

To get some insights into the internal working of rc_visard_opencv_example, this and the following section will explain how image streams are enabled and how the GenICam representation of images is converted to OpenCV.

Before enabling image streams, the connection to the rc_visard needs to be set up.

// Implemented in gc_receiver.cc

std::string rc_visard_id = "rc_visard";
// search for the device
std::shared_ptr<rcg::Device> device = rcg::getDevice(rc_visard_id.c_str());
// open the connection
device->open(rcg::Device::CONTROL);

The following code exemplarily shows how to enable streaming of the intensity image, which contains the left camera image.

// Implemented in gc_receiver.cc and image_receiver.cc

// get the node map
std::shared_ptr<GenApi::CNodeMapRef> node_map = device->getRemoteNodeMap();
// select the component "Intensity"
rcg::setEnum(node_map, "ComponentSelector", "Intensity");
// enable the selected component
rcg::setBoolean(node_map, "ComponentEnable", true);

// start streaming
std::vector<std::shared_ptr<Stream>> streams = device->getStreams();
streams[0]->open();
streams[0]->startStreaming();

### Converting GenICam images to OpenCV¶

Depending on the image type, there is a different conversion required to get from the GenICam representation to the OpenCV representation of an image. Here, we will show the simple example of converting the GenICam monochrome intensity stream to an OpenCV cv::Mat. For the other conversions, please refer to image_receiver.cc in the repository.

The queue in ImageReceiver provides images of type rcg::Image. Internally, the image data is stored in a contiguous block of memory in an eight bit representation, so each byte represents one monochrome pixel. Since cv::Mat uses the same eight bit representation, we don’t need any byte-to-byte conversion.

Yet, a simple copy of the memory block of rcg::Image into a cv::Mat is not ideal because rcg::Image may contain padding bytes appended to each image row. Therefore, we copy each row separately, while skipping the padding bytes, in order to generate a continuous cv::Mat.

// Implemented in image_receiver.cc

cv::Mat convert(const rcg::Image &buffer)
{
const int width = static_cast<int>(buffer.getWidth());
const int height = static_cast<int>(buffer.getHeight());

cv::Mat img(height, width, CV_8UC1);
// width of a row in the GenICam buffer including padding
const int buffer_step = width + static_cast<int>(buffer.getXPadding());
// data start pointer
const uint8_t *buffer_row_ptr = buffer.getPixels();
// iterate image rows
for (int row_idx = 0; row_idx < height; ++row_idx)
{
uint8_t *const img_row = img.ptr<uint8_t>(row_idx);
// plain byte-wise copy of one row from the buffer to the cv::Mat
std::copy(buffer_row_ptr, buffer_row_ptr + width, img_row);
buffer_row_ptr += buffer_step;
}
return img;
}


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# American Institute of Mathematical Sciences

2007, 2007(Special): 1-9. doi: 10.3934/proc.2007.2007.1

## Homogeneous coupled cell networks with s3-symmetric quotient

 1 Centro de Matemática da Universidade do Porto, Faculdade de Economia, Universidade do Porto, Rua do Campo Alegre, 687, 4169-007 Porto, Portugal 2 Centro de Matemática da Universidade do Porto (CMUP) and Dep. de Matemática Pur, Faculdade de Ciências, Universidade do Porto, Rua do Campo Alegre, 687, 4169-007 Porto, Portugal 3 Department of Mathematics, University of Houston, Houston TX 77204-3008, United States 4 Department of Mathematics, Purdue University, West Lafayette, IN 47906, United States

Received  September 2006 Revised  February 2007 Published  September 2007

A coupled cell network represents dynamical systems (the coupled cell systems) that can be seen as a set of individual dynamical systems (the cells) with interactions between them. Every coupled cell system associated to a network, when restricted to a flow-invariant subspace defined by the equality of certain cell coordinates, corresponds to a coupled cell system associated to a smaller network, called quotient network.
In this paper we consider homogeneous networks admitting a S3-symmetric quotient network. We assume that a codimension-one synchrony-breaking bifurcation from a synchronous equilibrium occurs for that quotient network. We aim to investigate, for different networks admitting that S3-symmetric quotient, if the degeneracy condition leading to that bifurcation gives rise to branches of steady-state solutions outside the flow-invariant subspace associated with the quotient network. We illustrate that the existence of new solutions can be justified directly or not by the symmetry of the original network. The bifurcation analysis of a six-cell asymmetric network suggests that the existence of new solutions outside the flow-invariant subspace associated with the quotient is 'forced' by the symmetry of a five-cell quotient network.
Citation: Manuela A. D. Aguiar, Ana Paula S. Dias, Martin Golubitsky, Maria Conceição A. Leite. Homogeneous coupled cell networks with s3-symmetric quotient. Conference Publications, 2007, 2007 (Special) : 1-9. doi: 10.3934/proc.2007.2007.1
 [1] Fernando Antoneli, Ana Paula S. Dias, Rui Paiva. Coupled cell networks: Hopf bifurcation and interior symmetry. Conference Publications, 2011, 2011 (Special) : 71-78. doi: 10.3934/proc.2011.2011.71 [2] Yu-Hao Liang, Wan-Rou Wu, Jonq Juang. Fastest synchronized network and synchrony on the Julia set of complex-valued coupled map lattices. Discrete & Continuous Dynamical Systems - B, 2016, 21 (1) : 173-184. doi: 10.3934/dcdsb.2016.21.173 [3] Fanni M. Sélley. Symmetry breaking in a globally coupled map of four sites. Discrete & Continuous Dynamical Systems - A, 2018, 38 (8) : 3707-3734. doi: 10.3934/dcds.2018161 [4] Sanjay Dharmavaram, Timothy J. Healey. Direct construction of symmetry-breaking directions in bifurcation problems with spherical symmetry. Discrete & Continuous Dynamical Systems - S, 2019, 12 (6) : 1669-1684. doi: 10.3934/dcdss.2019112 [5] A. Chauviere, T. Hillen, L. Preziosi. Modeling cell movement in anisotropic and heterogeneous network tissues. Networks & Heterogeneous Media, 2007, 2 (2) : 333-357. doi: 10.3934/nhm.2007.2.333 [6] Kashi Behrstock, Michel Benaïm, Morris W. Hirsch. Smale strategies for network prisoner's dilemma games. Journal of Dynamics & Games, 2015, 2 (2) : 141-155. doi: 10.3934/jdg.2015.2.141 [7] Gheorghe Craciun, Baltazar Aguda, Avner Friedman. Mathematical Analysis Of A Modular Network Coordinating The Cell Cycle And Apoptosis. Mathematical Biosciences & Engineering, 2005, 2 (3) : 473-485. doi: 10.3934/mbe.2005.2.473 [8] Thomas Hillen, Peter Hinow, Zhi-An Wang. Mathematical analysis of a kinetic model for cell movement in network tissues. Discrete & Continuous Dynamical Systems - B, 2010, 14 (3) : 1055-1080. doi: 10.3934/dcdsb.2010.14.1055 [9] Jeremy L. Marzuola, Michael I. Weinstein. Long time dynamics near the symmetry breaking bifurcation for nonlinear Schrödinger/Gross-Pitaevskii equations. Discrete & Continuous Dynamical Systems - A, 2010, 28 (4) : 1505-1554. doi: 10.3934/dcds.2010.28.1505 [10] Rui Hu, Yuan Yuan. Stability, bifurcation analysis in a neural network model with delay and diffusion. Conference Publications, 2009, 2009 (Special) : 367-376. doi: 10.3934/proc.2009.2009.367 [11] Ana Paula S. Dias, Paul C. Matthews, Ana Rodrigues. Generating functions for Hopf bifurcation with $S_n$-symmetry. Discrete & Continuous Dynamical Systems - A, 2009, 25 (3) : 823-842. doi: 10.3934/dcds.2009.25.823 [12] Lucio Cadeddu, Giovanni Porru. Symmetry breaking in problems involving semilinear equations. Conference Publications, 2011, 2011 (Special) : 219-228. doi: 10.3934/proc.2011.2011.219 [13] Hwai-Chiuan Wang. Stability and symmetry breaking of solutions of semilinear elliptic equations. Conference Publications, 2005, 2005 (Special) : 886-894. doi: 10.3934/proc.2005.2005.886 [14] Claudia Anedda, Giovanni Porru. Symmetry breaking and other features for Eigenvalue problems. Conference Publications, 2011, 2011 (Special) : 61-70. doi: 10.3934/proc.2011.2011.61 [15] Fang Han, Bin Zhen, Ying Du, Yanhong Zheng, Marian Wiercigroch. Global Hopf bifurcation analysis of a six-dimensional FitzHugh-Nagumo neural network with delay by a synchronized scheme. Discrete & Continuous Dynamical Systems - B, 2011, 16 (2) : 457-474. doi: 10.3934/dcdsb.2011.16.457 [16] Jiangtao Mo, Liqun Qi, Zengxin Wei. A network simplex algorithm for simple manufacturing network model. Journal of Industrial & Management Optimization, 2005, 1 (2) : 251-273. doi: 10.3934/jimo.2005.1.251 [17] Jae Man Park, Gang Uk Hwang, Boo Geum Jung. Design and analysis of an adaptive guard channel based CAC scheme in a 3G-WLAN integrated network. Journal of Industrial & Management Optimization, 2010, 6 (3) : 621-639. doi: 10.3934/jimo.2010.6.621 [18] Konstantin Avrachenkov, Giovanni Neglia, Vikas Vikram Singh. Network formation games with teams. Journal of Dynamics & Games, 2016, 3 (4) : 303-318. doi: 10.3934/jdg.2016016 [19] Joanna Tyrcha, John Hertz. Network inference with hidden units. Mathematical Biosciences & Engineering, 2014, 11 (1) : 149-165. doi: 10.3934/mbe.2014.11.149 [20] T. S. Evans, A. D. K. Plato. Network rewiring models. Networks & Heterogeneous Media, 2008, 3 (2) : 221-238. doi: 10.3934/nhm.2008.3.221

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# nds4droid release 18 and dynarec beta

First and foremost there is a new version of nds4droid up on Google Play and sourceforge. The changes are:

• Increased game compatibility, especially for Pokemon series games (thanks Sean)
• Added option to show only the touch screen (under “Select screens” in settings)

Also, I have been working on merging in the Exophase dynarec into nds4droid (thanks @sShake69). I have the build up and running but I’m not 100% comfortable making it the official build until I have some more time to test it out. Maybe you can help me! If you’re feeling adventurous, you can download the dynarec beta here from sourceforge. Let me know your experience with it! The beta is ARM-v7 (newer phones) only, fyi.

## 100 thoughts on “nds4droid release 18 and dynarec beta”

1. beeflot says:

Good job yall
haahaha

2. Tom says:

Anybody tried the Digimon World Dusk? It works fine on older build. Tried dynarec build, can’t move my character. But moving the menu and choose is working fine.

1. Tom says:

Sorry, I mean Digimon World Dawn. Gonna try the non-dynarec build soon.

1. Tom says:

Tested. On dynarec, I can’t move my character. On non-dynarec nds4droid 18, I can play normally.

But wow, the dynarec FPS are faster by averaging 5-10 FPS

1. shake says:

U mean it runs faster by 5-10 fps in comparison to the normal version?

1. Tom says:

Yes, around that amount in that game. I don’t know about the other. Just tested for a while.

Btw, i turned off sound, microphone and vsync.

2. Darron says:

Dsoid used to have that problem too. Now it’s fixed.

3. bea says:

My character doesnt move :'(

3. shake says:

You rock Jeff, and you too Sean 😀

Waiting to see the progess on the dynarec 8D

1. beeflot says:

shack i have replied you in r17: )

4. beeflot says:

we have tested the dynarec of r17
it works!!!!
but the compatibility is terrible…

5. Joy says:

I knew it. If a teenage can make dynarec to work in Dsoid, you can do it too.

6. beeflot says:

well well well,what a brilliant day today.
dsoid update to 1.9.12
Added frameskip and the ability to disable sound.

7. Sam says:

I love to see better ds emulators, but looking into the source, it seems the dynarec is just copied from Dsoid. But jeff never mentioned if he got dsoid source legitimately. It’s morally wrong and illegal to steal other’s code.

1. beeflot says:

No no no,it’s not illegal nor stealing.
Fistly,the dynarec of dsoid actually is the one of gpsp made by exophase,which is under GPL . And Jeff mentioned exophase.
Secondly,Qingping ,the developer of dsoid said “Email for source
” on play store.

2. jeffq says:

All of the code that Dsoid uses is GPL, which means he has an affirmative legal obligation to share all changes. What’s immoral and wrong is for him to sell other people’s work (DeSuME and the dynarec by Exophase, both of which are under the GPL).

1. wistaria says:

The terms and conditions of the GPL must be made available to anybody receiving a copy of the work that has a GPL applied to it (“the licensee”). Any licensee who adheres to the terms and conditions is given permission to modify the work, as well as to copy and redistribute the work or any derivative version. The licensee is allowed to charge a fee for this service, or do this free of charge. This latter point distinguishes the GPL from software licenses that prohibit commercial redistribution. The FSF argues that free software should not place restrictions on commercial use, and the GPL explicitly states that GPL works may be sold at any price.

2. wistaria says:

Extracted from wiki,so you think it’s immoral and wrong?

3. Sam says:

Jeffy, you are wrong. GPL explicitly says you can sell. Your response indirectly confirms that you are using Dsoid dynarec, but you didn’t answer my question if your Dsoid source was a legitimate copy. If it is, you should at least give credit to the dsoid author. If it is a stolen copy, I understand why you don’t want to do so, but it is unprofessional and immoral to attack Dsoid besides stealing is illegal.

4. Sam says:

Well said by wistaria. GPL says you can sell,but doesn’t say you can steal.

1. beeflot says:

No , Jeff didn’t steal it.
It is shack that emailed him .
This is what shack said.
“I got the actual source code….dont know about that, the developer himself gave it to me, and i said it was for a friend that is working on a emu for ds for android and it was having problems implementing the dynarec”

1. Anonymous says:

Frankly, Jeff should have acknowledged that it is based on dsoid instead of pretending he made it himself and demoralizing dsoid.

2. Sam says:

Still sounds like stealing from Dsoid

3. Anonymous says:

I would just call it dishonest instead of illegal or stealing if without proper aknowledgement of others work.

4. beeflot says:

“ pretending he made it himself and demoralizing dsoid. ”
You have a good inmagination.

5. Anonymous says:

hey beef. Jeff clearly says he worked out dynarec while the fact is he copied dsoid. he also says the dsoid author dishonest and immoral. you are saying all these are imagination. If you have difficulty comprehending what he says, go back to school and study American English harder. Otherwise it only shows your ignorance.

5. Anonymous says:

Really? it’s wrong to sell under GPL? Come on Jeff, If you are not ignorant then you are vicious. Be thankful and honest.

3. dsdroidfan says:

how can you steal something that is mean’t to be shared?

1. Anonymous says:

8. i'm gamer says:

Nice done

please , start work on mario series …

pleeeeeeeeeaaaaase

super matio bros , mario and luigi bowser inside story , mario and luigi ….

9. Pierce says:

Dyanrec beta has improved performance significantly.
Compatibility updates are also much welcome.

Thanks!

I’d like to know what users with more powerful phones experience.
Maybe someone with a Nexus 4 or even a Galaxy SIII (Exynos version) could drop a word?

10. Zamran says:

The beta looks promising, really looking forward to dynarec on nds4droid, but compatibility of the beta leaves a lot to be desired, but that will get fixed no doubt
nds4droid 18 is cool, all Pokemon games start now

11. hey man says:

oh jeff, you sly devil, gonna try this when my wife gets home, cus she gots my G tab. stay awesome man.

12. kRn says:

Phoenix Wright 30FPS in the court. works really nice, GJ Jeff.

13. kRn says:

I forgot…on the NEO V 2.3.7

14. Evaristo Velasco Pastor says:

In DEsmume fork with treath interpreter got 38 fps at “dbz attack of sayans”, now with nds4droid 18 had got 40-41 🙂 its better thanks jeff and sean 🙂

15. Antuan says:

With the last dynarec update i finally consider new super mario bros to be playable in my phone, 35-40 fps. Very much appreciated Jeff, you are doing a great job.

I would love this project to follow the path of ppsspp, with the github and forum community, it is really great to watch how things happens and be a part of it in a way. That would atract also a number of developers, i am sure 😀

16. Evaristo Velasco Pastor says:

Dsoid is more faster now, dbz ultimate kai now is playable also had got very glitches 🙁 nds4droid will be better than dsoid when Jeff and Sean will depured dynarec beta code .. sorry my english 😛

17. Sean Maas says:

1. dsdroidfan says:

i’ve noticed slight speedup in the world in pokemon diamond.

18. Evaristo Velasco Pastor says:

jeff and sean the “D-ream S-team” lol

1. beeflot says:

Haha,good idea

19. Evaristo Velasco Pastor says:

i like that we created a forum like as ppsspp it will be interesting and nds4droid avanced a lot sorry my enlighs im spanish xD

1. beeflot says:

Shack also want to creat one: )
He’s off-line now

20. Evaristo Velasco Pastor says:

but i dont know how create a forum 😛 but i can be game betatester 🙂

1. beeflot says:

……

1. Evaristo Velasco Pastor says:

I have not idea but i want to help on everything that i can do it 🙁

1. beeflot says:

That’s good ,however: )

21. shake says:

well, its sad to see that jeffs getting some hate for using dsoid dynarec, dsoid dynarec its exhophase dynarec, which is under gpl and can be modified and used by others, ofcourse jeff could mention thats is using dsoid dynarec, but its the same as saying he’s using exhophase’s dynarec, its up to him, i was the one who sent him the code, and it was the developer of dsoid who gave it to me, i said a friend wanted to implement dynarec, and was having problems, if he could send me the source, he sended, so i think he’s ok with it.

Yall should be happy, that the android scene is gettin better is terms of the nintendo ds emulator instead of complaining about stupid things.

Dsoid had a update?ok thats great, i support both nds4droid and dsoid, i actually bought it long time ago, instead of crying do the same as me and support both.

1. Antuan says:

I totally agree with you. The best thing would be them working together, though

1. shake says:

“Hi, Thank you, would you mind if he uses the dynarec code and give you credit? Cheers”

He said:

“No, I don’t mind, but who is he (your friend)?”

I said it was the developer of nds4droid, so jeff, if you dont mind, you could mention him in the next release so people stop bitchin about it.

2. Sam says:

Yes, “Its up to him” to choose to be professional, moral, and legitimate. He appears to intentionally not mention that his beta is not based on Dsoid’s dynarec and pretend he worked it out. It’s a lack of judgement and morally wrong.

2. Sam says:

“ofcourse jeff could mention thats is using dsoid dynarec”? No, not “could”, he should. If you look into the code, you will see that Dsoid dynarec is based on but not the same as exphase dynarec. It’s not “the same as saying he’s using exhophase’s dynarec”.

3. Anonymous says:

I would just call it dishonest instead of illegal or stealing if without proper aknowledgement of others work.

22. Evaristo Velasco Pastor says:

desmume alpha 7 crash everytime..

23. jeffq says:

Okay let’s just clear this up. The dynamic recompiler was written by Exophase. Writing a dynamic recompiler is *very hard*, and it’s to him the credit should go. The part I used from Dsoid is how to hook up the recompiler into DeSmuME. The only part that Dsoid wrote was the “glue” of them together — to me, the credit goes to the person who wrote the hard part (the recompiler). It should also be noted that desmumefork did this glue work independently as well.

The thing is, 90% of the code in all these apps comes from other sources, not the final app publisher. The Dsoid guy took 95% of other people’s code and has mode > $20,000 on the Google Play store from it. I have made a grand total of$200 from donations from nds4droid. Don’t mistake me, I’m not in this for they money — I recognized that since most of the code I was using was from other people it would be dishonest for me to charge/put ads in it when most of it wasn’t my work.

1. shake says:

Nice explanation, now yall cant stfu with that crap and enjoy nds4droid and dsoid.

1. beeflot says:

Once , I thought it is only in China where there are many people who like crap.
I found I’m wrong : (
However, here is jeff’s blog.
If it was a forum, we can just delete it and make crap forbidden.: (

1. Anonymous says:

While in America you’ve got to abide by American rules not China’s.

1. beeflot says:

And I always obey the rules , both Chinese and American.

2. Anonymous says:

Oh my god, you guys in China just delete different opinions and say they are crap?

1. rmc says:

No.We like different opinions but hate craps.
Different opinions make people happy because it is constructive.
Craps only make people angry.
Is it different in America or some other country?

2. Anonymous says:

One opinion in country A may be regarded as crap, and in country B may be core value and vice versa. Examples of such debatable opinion are views on human rights, freedom of speech and democracy. If one dislikes an opinion and can just labels it crap and kills it, it’s scary.

3. Anonymous says:

You are right
But it’s not disliked by one person .
It’s disliked by many people
And kill some opinions make something peace
I don’t think every opinion is valueable.And some opinions are really scary.

4. Anonymous says:

You are still debating here? OK, let me teach you. I am sure your country is not the US. Your country must be a place where there is no freedom of speech, human rights, or democracy. According to your weird logic, your posts should be deleted immediately because all Americans are against it. Since Americans believe in freedom of speech, you should feel really lucky that your posts are still hanging here.

2. Onij Jokuma says:

Thank you Jeffq! I can’t wait when your NDS4Droid gradually merges with the dynarec! I honestly think a lot these users are being ridiculous. Though I have no clue of this situation, you gave credit to Exophase, however, some of them seem to think you’ve stolen this… However, Shake explained how this occurred and they still can’t comprehend that you didn’t steal this and that you gave credit to the man himself who created this… I would like to say thanks and I will enjoy to record this emulator and all it’s dynarec goodness!

3. Anonymous says:

The fact is that you used Dsoid source code and its modified dynarec, even though the percentage of effort is just your subjective opinion. That you made less money can’t be an excuse to deny Dsoid’s valuable contribution.

4. Sam says:

Although exophase dynarec has been there for years, you failed to make it work until you copied Dsoid. You should have acknowledge that it’s also based on Dsoid from the beginning. No, you didn’t. You tried to fool us users that you made a dynarec work. That’s dishonest and not acceptable by any standards.

5. Sam says:

Once I had hope in your emulator even if it was slower than Dsoid. Now, your behavior becomes acceptable until you make corrective action. You have to honestly acknowledge other people’s effort as long as you touched it.

6. wistaria says:

I don’t think you are stealing,but you shouldn’t at least demoralize dsoid.

7. Anonymous says:

In our engineering world, we always acknowledge other people’s effort if we touch their work. I believe it’s common sense to professionals in any field.

24. beeflot says:

Shack , we need a forum (-.-)

1. shake says:

i have to buy a new phone, so yall gotta wait some time, but jeff has this site, he could host a forum on it as a subdomain.
Lets see if he says something when he sees this.

1. beeflot says:

ok : )

1. Your thniikng matches mine – great minds think alike!

25. gamer says:

Overall great. But I need it to be faster more fps plz. Great job

26. beeflot says:

good job jeff and sean

27. Seal says:

R18 also has some speedup XD

28. rmc says:

it will be good if nds4droid has its own dynarec
Come on jeff : )

29. jeff_fun says:

Have you guys run Pokemon black2 on nds4droid r
18?

30. Billy says:

Hey guys i found the latest PPSSPP could run pspkvm0.3.2.
The porformance for 2d games is great！

31. kommodoro says:

Thank you jeff in first place, because you started the nds4droid emu, and second to sean that he continued and gave more compatibility to his great dsdroid, i think, in my poor opinion that you are going to be hate (for the dynarec, if it was from dsoid or exophase), for one simple reason, your work is for FREE, you dont seek any money, and thats the main reason that you (jeff), the all anonymous messages are anoying you that if you should give credit to dsoid developer or not,that you are a thief, and all this things… the main think i want to say is thank you (jeff and sean) for this great emulator, and so many many THANKs to give it for FREE.
(sorry if i had some errors, because english is not my lenguage).

32. devildragon says:

Fantastic work

Come on,jeff.
i have heard that exophase would release DraStic in next half of this year.

34. Mage says:

Such a good app.

One issue that I have noticed is that you can bind the MENU and BACK buttons, which should not be able to happen (IMO), as you cannot change them back (although, if you re-install, your save-states stay exactly as they were, so any settings you feel iffy about, you can always re-install and keep your places).

I also suggest a way to un-bind buttons. I found some difficulty when I accidentally bound the VOLUME_UP button incorrectly, and when I re-bound it, the game interpreted both actions.

Keep up the excellent work. If it runs bearably on my piece of [email protected]$# phone, then it can’t be too bad on better, higher end ones. 35. Lucas says: Hey guys, wondering which Pokemon games are improved? I’ve a nexus 7 and heart gold is still unplayably slow even with new update. 1. Lucas says: so is platinum 36. Ds Games is my name says: Jeff you made à 18 versoisn and you didnt tell me i tough wé ware friands.. friends tell friends stuff like this alsome ds you made (THANK-YOU JEFF 37. Joy says: I thought Jeff would team up with Dsoid to make a perfect DS emu. This thread is telling me that Jeff hates the DSoid author because (1) Jeff thinks to charge a fee violates GPL and (2) Jeff thinks Dsoid’s dynarec implementation is nothing. Come on Jeff, you know GPL allows you charge whatever fees you like. You have to admit that DSoid is worth more than$10. Is it nice for you to disgrace Dsoid at the same time you are using its code which is CRITICAL for your app?

38. Hi jeff you fianlly did it pokemon diamond finally work and it really plays good. thank you for all you hard work. please if you like check me out at youtube.com/finalsample5

39. Anonymous says:

This is disgusting. You are using Dsoid code for your (cr)app. It’s shameless enough that you did not say thanks to the author. You went further being so rude to him. Who else on earth is more shameless?

40. brian says:

First i like to thank jeff for all his hard work on this he was the one who started this

To all the people who are bitching and complaining about if he stole it or what do me favor and put ur head back up ur ass were it belongs i dont see your emulator on the play store so fuck off

Jeff thank you again for doing all this on your spare time

1. Hahaha good one brian your funny i agree with you brian. people of spring field stop bitching jeff up and start thanking him for his hard work. and if you dont like his work then why are you here. THANK YOU JEFF FOR ALL YOUR HARD WORK. I DONT MEAN TO TROUBLE YOU BUT YOU FIX POKEMON DIAMOND AND IT WORK GREAT BUT CAN YOU FIX THE SOUND TOO PLAY MUCH BETTER AND FASTER QAND CAN YOU SPEED THE GAME UP A LITTLE BIT MORE. (THANKK YOU)

41. chicki says:

I support this app. my samsung S2 plays my ds games through NDS4DROID and it plays them at 85% compared to a real nintendo ds. I am happy and so should you all be. So what he didn’t acknowledge help right now, Jeff can say it when work on the dynarec is finished or whatever.

42. Anonymous says:

The dynaric is good and that’s what you should care about not who ownes it, like pussy
(Purposely aggravating)

43. Anonymous says:

Why are there so many un-civilized people on this website?

1. Anonymous says:

I am not saying all. You don’t have to announce to the world if you think you are un-civilized.


text:
3.5

## Raspberry Pi Foundation

Skip to 0 minutes and 1 secondThere are many different types of data. And different programming languages have the their own rules governing how different data types are treated. In Python for instance, characters such as A or question mark are called strings. You can query different objects using the type of function. So by typing "type" and then the string "hello," I can find out that this is a string. Similarly, type and "I am learning Python" should return the same result. Other data types you should know about are ints, which is short for integer. These are whole numbers like 1 or 1,000. Another numerical data type is the float. This is an implementation of a fraction, such as 1.0 3.142.

Skip to 0 minutes and 57 secondsThere are many other data types such as lists, dictionaries, and sets. And as you become more experienced with Python, you'll learn more about these data types. Different operations in Python will have different outcomes depending on the data type used. So adding the integer 2 to another integer 2 produces the integer 4. Whereas, adding the string 2 to another string 2 will produce the string 22. And adding a list containing the number 2 to another list containing the number 2 will produce a list containing two values of 2. Luckily in Python, it's fairly easy to switch between data types. This is called typecasting. For instance, here I'm going to set a variable and give it the value of the string 3.

Skip to 1 minute and 50 secondsSo when I query what type this is, it should return class string. Now because my_num is a string, I can't add it to another integer. So for instance, if I type my_num plus 3, the interpreter will tell me that I cannot add a string to an int. I can however, add a string to a string. So my_num plus the string of 3 should give you the string 33. If I want to use my_num in calculations, I must first typecast it to an integer. I can do this by typing int and then the variable name. Then, I can add it to 3 and we'll get the output 6.

Skip to 2 minutes and 34 secondsI could also create a new variable called my_new_num, which is equal to the int of my_num. Now, the type of my_new_num will be an int.

Skip to 2 minutes and 50 secondsBecause my_new_num is an int, it's impossible to concatenate it with a string. So typing "my_new_num is" and then adding on my_new_num will error because you can add strings and ints together.

Skip to 3 minutes and 9 secondsTo concatenate the value of my_new_num to a string, I must first typecast it from an int back into a string. So "my_new_num is" plus and then string of my_new_num.

Skip to 3 minutes and 27 secondsNow, it's time for a challenge. You learned about getting user input in the mad libs exercise last week. For example, you can type num equals input, give me a number, and this will ask the user to input a number. However, this number will always be a string, so you can't perform calculations on it. Your next challenge is to make a programme that asks the user for the real age of a dog and then converts this to an integer. Then, calculate the dog's age in dog years-- so multiply by 7. Turn this result back into a string and then output the results so the user can see how old the dog is.

Skip to 4 minutes and 18 secondsThere are a few ways to do this, but you might find it easier if you jot it down in pseudocode first to help you figure it out. As always, you can share your achievements in the comments below.

# Data types and dog years

There are many different types of data, and different programming languages have their own rules governing how different data types are treated.

In Python, for instance, characters such as 'a' or '?' are called strings. You can query an object to see which data type it represents, using the type() function. For instance:

type('Hello')

This tells you that 'Hello' is a string, as is "I am learning Python". (Single quotes ' and double quotes " are functionally equivalent when working with strings in Python.)

Other data types include integers, which are whole numbers such as 1 and 1000, and floating point numbers, which are implementations of fractions, such as 1.0 or 3.142.

There are many other data types, such as lists, dictionaries, and sets, which you will learn more about as you become more experienced in Python.

Python recognises various data types and will only allow certain operations on certain types of data. Let’s look at a practical example:

>>> print(2 + 2)
4
>>> print('2' + '2')
22
>>> print([2] + [2])
[2, 2]

In the first line, the numbers were integers, so the Python interpreter added them together. In the second line, the data was in the form of strings. The Python interpreter concatenates strings when it’s told to add them together. In the last line of code, each 2 was surrounded by square brackets. This meant they were lists, and the interpreter merged the lists into one.

Changing data types is fairly easy in Python. Doing so is called type casting. The most common examples of type casting is changing numbers to strings and back again. For instance, here a variable is being declared with a value of '3':

>>> my_num = '3'
>>> type(my_num)
<class 'str'>

As this is a string, it can’t be used in calculations with an integer.

>>> my_num + 3
Traceback (most recent call last):
File "<pyshell#14", line 1, in <module>
my_num + 3
TypeError: must be str, not int

To use my_num in calculations, it must first be type cast as an integer.

>>> int(my_num) + 3
6

You could also create a new variable that is the int of my_num. For instance:

>>> my_new_num = int(my_num)
>>> type(my_new_num)
<class 'int'>

If we want to use my_new_num with a string, it needs to be type cast as a string. For instance:

>>> print("My new number is " + str(my_new_num))
My new number is 3

Here we’ve used two of Python’s built-in functions: int() to turn a string to an integer, and str() to turn an integer into a string.

## Challenge

You learned about getting user input in the Mad Libs exercise last week. For example:

num = input('Give me a number ')

This always saves the user’s number as a string though.

Your challenge is to write a program that:

1. Asks the user for the real age of a dog
2. Converts this to an integer
3. Calculates the dog’s age in ‘dog years’ (multiply by 7)
4. Turns this result back into a string
5. Outputs the result so the user can see how old the dog is

There are a few ways to do this, but you will probably find it easiest if you jot down a little pseudocode first to help you figure it out.


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# How do gluons bind the quarks together within the hadrons and mesons?

I was trying to know about the strong nuclear force within the nucleus and the books and websites told me that it is the gluons which carry the force, and now I am curious how the gluons carry this force

• Do you understand how photons carry electromagnetic force? If not, you should start with that. – G. Smith Jan 4 at 10:15

As in your profile you say you are a ninth class student in India, it means that your physics background is still at understanding the classical physics level.

The strong nuclear force and the strong force of particle physics belong to the quantum mechanical studies, which I doubt it is taught in your year.

In classical physics force can be defined as the change in momentum in time, $$F=dp/dt$$. At the level of nuclei and particles, this is the only reasonable definition of a force, because any interaction between quantum mechanical entities happens by the exchange of an elementary particle which transfers energy and momentum and quantum numbers ( which you will eventually learn about) between the quantum mechanical entities, be they nuclei or particles.

Think of two boats in a quiet sea. If one boat throws a ball to the other, they interact with the $$dp/dt$$ the ball carries. That is how forces are to be defined in the micro level of nuclear and particle physics. In this answer here , there is an illustration of the boats with a boomerang thrown, to show an analogy with attractive forces. ( the feynman diagrams are for later in your education, if you still like physics and pursue it)

The elementary particles carrying the force to first order in most interactions are:

the photon, for electromagnetic interactions

the Z and W for weak interactions

the gluon for strong interactions

For nuclei, which are bound states of protons and neutrons, the strong nuclear force, is a spill over force from the strong force which has the gluon as a force carrier . Interaction of nuclei can be modeled by having the composite hadron particle pion as a force carrier.

Protons (and neutrons and other hadrons) are an entity with three valence quarks held together by an innumerable number of gluons as force carriers, because gluons are very attractive to quarks and to each other. ( the word comes from glue)

Here is an illustration of a proton:

The three valence quarks are lost in the plethora of gluons and quark antiquark pairs created by the mechanism of strong interactions.

The strong force is so strong that new quantum mechanical models have been developed to explain the hadrons ( bound states of quarks by gluons), called QCD on the lattice.

• (The three valence quarks are lost in the plethora of gluons and quark antiquark pairs created by the mechanism of strong interactions.)-please explain this I couldn't get it – Austin Rojers Jan 4 at 9:21
• And thanks, you explained it nicely understanding my level – Austin Rojers Jan 4 at 9:25
• a gluon caries energy, if its energy is larger than the mass of a quark antiquark pair, the quantum numbers can be satisfied, and a pair of quark antiquark appears. The only measurements we can make are scatterings., example, electrons off a proton, The functional behavior of the produced particles from the scattering can be well described by parton distribution functions, i.e. quark , antiquark and gluon. energies within the hadron.. that is for later studies – anna v Jan 4 at 10:13
• The quarks then can annihilate with the antiquarks and create gluons, and the whole ball is held together because the strong force is very attractive. "become lost" I mean in the illustration of proff Matt Strassler. – anna v Jan 4 at 10:15
• Yes, but it holds for same energy levels and quantum numbers. Within the proton the energy levels due to the strong interaction can be considered continuous, there is no problem of two same color quarks occupying the same level, there is always infinitesimally close another energy level. – anna v Jan 4 at 19:32


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# Inverse Trig Differentiation

1. Oct 21, 2009

### quozzy

Alright, I'm not technically stuck on this one, but I consistently get a result that disagrees with what Wolfram Alpha shows when I enter the problem to check my answer. Sorry 'bout the lack of LaTeX, but it should be simple enough to read. Here goes:

Problem:
Differentiate y=sin-1[x/(1+x)]

Basically, I rearrange for
sin(y)=x/(x+1)

then use implicit differentiation to yield:
* ---> cos(y)*(dy/(dx))=1/(x+1)2

Substituting with:
cos(y)=sqrt[1-sin2(y)]

I get:
cos(y)=sqrt[1-x2/(x+1)2]

which simplifies to:
cos(y)=sqrt(2x+1)/(x+1)

Dividing both sides of the original equation (above, marked with a star) by cos(y):
dy/(dx)=1/[(x+1)sqrt(2x+1)]

Which, if you don't like surds in the denominator, can be simplified to:
sqrt(2x+1)/[(x+1)(2x+1)]

I've done this question several times, and re-checked all my working. For the life of me, I can't see where I go wrong, yet my result is slightly different to what it should be. Any suggestions would be most welcome.

2. Oct 21, 2009

### Bohrok

This is pretty close (and equivalent) to the first alternate form of the derivative on Wolframalpha.

3. Oct 21, 2009

### Dick

What do you think it should be?

4. Oct 21, 2009

### quozzy

Huh. It appears you're right. I had even tried entering <my answer> - <w.a. answer>, and it came out nonzero, but I must have mistyped something. Well, I'm glad I'm not missing anything. Thanks for the clarification!


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 Inverse super-composition Xorter Junior Fellow Posts: 46 Threads: 14 Joined: Aug 2016 01/12/2017, 04:19 PM Okey, I have found something looking like the solution. I feel I am closer than ever before. For the following functional equation $2x ^{oN} = exp(x)$ my method gives: $N = 0.5250548915-0.2859572213x+0.3455886342x^2-0.0759083804x^3+0.0201418181x^4-0.0045151851x^5+0.0006517298x^6+...$ Let us check it: $2x ^{o0.5250548915-0.2859572213x+0.3455886342x^2-0.0759083804x^3+0.0201418181x^4-0.0045151851x^5+0.0006517298x^6+...}$ looks like sg like the exoponential function. Of course, because at x=0 exp x = 1, then x2^n will never go up to 1, so in the reals there is no more beautiful solution for N like mine, I think or I am wrong, ain't I? What do you think, is this function correct? Or is there better? Xorter Unizo « Next Oldest | Next Newest »

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