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# Python 3 tasks

If you want to know how to run Python scripts on Windows (in its command prompt), read the FAQ.

If you want to learn more about Python, you may try these: an Italian tutorial, a good open source book translated into Italian, official Python tutorial (in English). You will find many more tutorials on the Internet and you may even look at video tutorials on YouTube or do some interactive tutorials. You Google it!

You will find anwsers to many questions related to Python programming at stackoverflow.

You may use the online tool repl.it but I recommend you to install Python 3 on your computer. You will find many how-tos online (just Google it), you may use e.g. this. After the installation you can interact with Python in a few ways, more info here.

### Expressions

Write the following formulae as Python expressions. Print out the results.

$${2^{(2+3)}} \over {(8\times2)}$$

# "to the power of" is written as **
a = 2 ** (2+3) / (8*2)
print(a)
# 2 ** ((2+3) / (8*2)) would give a different result!

$$\sqrt x$$

You may use the fact that

$$\sqrt[{n}]{x}=x^{\frac {1}{n}}$$

# square root of x is x to the power of 1/2
x = 10
print(x**(1/2))

### Area of a general triangle

If a, b, c are sides of a general triangle, then

$$s = {{a+b+c} \over 2}$$

and

$$area = \sqrt{s \times (s-a) \times (s-b) \times (s-c)}$$

Define three variables a, b, c. Be aware of triangle inequality. Write these formulae as Python expressions.

a = 4
b = 5
c = 6
s = (a+b+c)/2
area = (s*(s-a)*(s-b)*(s-c))**(1/2)
print(area)

### Floating point precision

The precision of floats (real numbers) is not unlimited.

# the following evaluates to True
1.00000000000000000000001 == 1
# the following evaluates to False
0.1 + 0.1 + 0.1 == 0.3

Learn more about floating point precision and the next time you won’t be surprised.

### Numeral systems

I’ve briefly spoken about hexadecimal and binary number systems. Read more about it (in Italian) as you may encounter some of the systems in the future.

For the following you will need to use so called list comprehension. This is very useful expression in Python as it allows to create a list in a very flexible way. So first, the general syntax is this:

l = [expression for item in list if condition]

It reads as follows: for each item from list, evaluate expression and put it into the resulting list if condition is True.

This is very powerful since you can generate e.g. a list of even numbers easily:

evens = [x for x in [1, 2, 3, 4, 5, 6] if (x % 2) == 0]

You can also use more complex expression to be evaluated, e.g.

evens_squared = [x**2 for x in [1, 2, 3, 4, 5, 6] if (x**2 % 2) == 0]

which will generate a list of numbers which are even when squared.

For the following task you will also need enumerate function which takes a list and creates a new list where the items of the list are enumerated with numbers.

print(list(enumerate([5,6,7])))

Here we need to explicitly convert it into list with function list otherwise we would use Python’s abstract representation of the enumeration. It is for technical reason (to safe memory space), just take this as a fact. :) Notice that the enumeration starts at 0 as with list indexes.

### H-index

H-index is used for comparing academic performance of researchers and institutions using the number of citations of their papers. If L is the list that corresponds to the list of numbers of citations for each publication, we compute the h index as follows. First we order the values of L from the largest to the lowest value. Then, we look for the last position in L where the value is greater than or equal to the position (we call h this position).

Your task is for a given list of numbers representing number of citations to compute the h-index. Since we don’t know iteration over list items in a loop yet we can use list comprehensions.

citations = [5, 20, 1, 7, 8, 14]
citations.sort()
citations.reverse()
hindex = len([x for i, x in enumerate(citations) if x >= i+1])
print(hindex)

### Palindrome

Palindrome is a word (a string) which reads the same backward as forward. Define a variable x and then write an expression which will evaluates to True if and only if x is a palindrome.

x = "1234321"
l = len(x) // 2

"""
we use list comprehension with a condition which will test characters from the
left and from the right at the same time. It is enough to test up to the centre,
to the index l. We generate comprehension list in the way that its length is
equal to l only if the word reads as palindrome. The character in the middle is
omitted.
"""
indexes = [i for i in range(l) if x[i] == x[-i-1]]
# -i-1 because we compare x[0] to x[-1], x[1] to x[-2] etc.
is_palindrome = len(indexes) == l
print(is_palindrome)

### 3rd May

By calling set([1, 2, 3]) you can turn a list into a set. You can do a similar conversion between a list and a dictionary with function dict but since in a dictionary, we need to have pairs key-value, the list we will convert must be in the form of pairs (lists) where the first items will be used for keys and the second items for values. Try this: dict([[1, 2], [2, 3], [3, 4]])

Or you can try this: dict([["a", 1], ["b", True], ["c", "TEXT"]])

The result is a dictionary with the key-value pairs taken from the list of lists. Be aware that the sublists must always contain two items.

You can turn any list into a dictionary with numerical keys like this:

dict(enumerate(["a", "word", 1, 5.2, True, [3, 9]]))

### Lexicon

We saw how to turn a text into a frequency list. With dictionaries it is more natural. We will turn words into keys and their frequencies into values. Your task is to copy a text from Internet, store it in a variable text, remove punctuation, split into words (tokens) and pick one word from it and print out its frequency. You will again use the list comprehension which will generate the list of pairs (a word and its frequency) which you will turn into a dictionary with function dict. Then you can access the picked word with your_dictionary[your_word_of_choice]
The dictionary data type is very suitable for this task.

text = """Harari is interested in how Homo sapiens reached their current condition, and in
their future. His research focuses on macro-historical questions such as: What
is the relation between history and biology? What is the essential difference
between Homo sapiens and other animals? Is there justice in history? Does
history have a direction? Did people become happier as history unfolded?
Harari regards dissatisfaction as the "deep root" of human reality, and as
related to evolution.
In a 2017 article, Harari has argued that through continuing technological
progress and advances in the field of artificial intelligence, "by 2050 a new
class of people might emerge – the useless class. People who are not just
unemployed, but unemployable." He put forward the case that dealing with
this new social class economically, socially and politically will be a central
challenge for humanity in the coming decades.
Harari has commented on the plight of animals, particularly domesticated animals
since the agricultural revolution, and is a vegan. In a 2015 Guardian article
under the title "Industrial farming is one of the worst crimes in history" he
called "the fate of industrially farmed animals [...] one of the most pressing
ethical questions of our time."
Harari summed up his views on the world in a 2018 interview with Steve
Paulson of Nautilus thusly: "Things are better than ever before. Things are
still quite bad. Things can get much worse. This adds up to a somewhat
optimistic view because if you realize things are better than before, this means
we can make them even better."
Harari wrote that although the idea of free will and the liberal values it
helped consolidate "emboldened people who had to fight against the Inquisition,
the divine right of kings, the KGB and the KKK", it has become dangerous in a
world of a data economy, where, he argues, in reality there is no such thing,
and governments and corporations are coming to know the individual better than
they know themselves and "if governments and corporations succeed in hacking the
human animal, the easiest people to manipulate will be those who believe in free
will." Harari elaborates that "Humans certainly have a will – but it isn’t
free. You cannot decide what desires you have. Every choice depends on a lot
of biological, social and personal conditions that you cannot determine for
yourself. I can choose what to eat, whom to marry and whom to vote for, but
these choices are determined in part by my genes, my biochemistry, my gender, my
family background, my national culture, etc – and I didn’t choose which genes or
family to have."
"""

# I can compose replace methods like this:
text = text.replace('.', '').replace(',', '').replace(':', '').replace('"', '')
# split without an argument splits at whitespaces (newlines, tabulators, ...)
tokens = text.split()
# list comprehension will generate pairs [word, word_count]
# it doesn't matter there are duplicities, the dictionary stores unique keys
lexicon = dict([[x, tokens.count(x)] for x in tokens])
# print out the frequency of word "people"
print(lexicon["people"])

### Interlanguage homonyms

Here you have two lists of top 100 English and Italian words. Your task is to find the common words in the lists which should give you the homonyms or false friends or “international” words.

English: the and of to a in for is that on with it as are i this be by at from was you we have or an will not has their can they but all he more our his which one your new about also who there were if my been so other do its when what up out had time would these n’t some her people into how first work them she like than may no us only through over many two most just after any years use such said now well information year very where me make world get

Italian: di e il la che in a per un del è l’ con i della non le una si da al dei sono nel più come ha delle alla dell’ ma anche o gli se ed ad dal lo questo nella all’ essere su cui ci alle tra ai dalla degli mi tutti sul solo d’ hanno questa due anni loro stato parte prima sua sia sempre un’ tutto ho era uno suo dopo molto sulla può ogni c nei quando poi nell’ senza perché così ancora quello tempo fare fatto dall’ nelle vita quanto proprio altri chi lavoro dove

english = """
the and of to a in for is that on with it as are i this be by at from
was you we have or an will not has their can they but all he more our
his which one your new about also who there were if my been so other do
its when what up out had time would these n't some her people into how
first work them she like than may no us only through over many two most
just after any years use such said now well information year very where
me make world get"""

italian = """
di e il la che in a per un del è l' con i della non le una si da al dei
sono nel più come ha delle alla dell' ma anche o gli se ed ad dal lo
questo nella all' essere su cui ci alle tra ai dalla degli mi tutti sul
solo d' hanno questa due anni loro stato parte prima sua sia sempre un'
tutto ho era uno suo dopo molto sulla può ogni c nei quando poi nell'
senza perché così ancora quello tempo fare fatto dall' nelle vita quanto
proprio altri chi lavoro dove"""

# I can intersect sets so I need to convert the list of words
# into sets and only then I can use & operator
intersection = set(english.split()) & set(italian.split())
# I want to sort the intersection so I need to convert the set into a list
intersection_list = list(intersection)
# now I can sort it
intersection_list.sort()
print(intersection_list)

### Sort words in retrograde order

On the internet you will find many wordlists, here you will find 1,000 Italian words which we will use in this example. The task is to save the list and open it from a script and store the words into a list. Then to sort the list alphabetically but consider the words from backward. So “abc” will be after “cba” since the former ends with “c” and the latter with “a”. By sorting the list this way you can discover some common suffixes of words. It will put together words which rhyme with each other.

# we need the file in the same directory as the script
f = open("italian.txt")
italianWords = []
for line in f:
# each line ends with "\n", remove this with strip() method
word = line.strip()
# now we generate the retrograde string (we can't use reverse, it is only for lists
revword = ""
# we create the reversed word character by character
for character in word:
# by prefixing the current partial word with the current character
revword = character + revword
# if word was "abcd", revword now contains "dcba"
# we append pair ["dcba", "abcd"] as an item to the whole list
italianWords.append([revword, word])
# now we processed all words from the file
# if we sort the list, it will sort according to revwords
italianWords.sort()
for item in italianWords:
# item[0] is the reversed word, we will print the second item (original word)
print(item[1])

### Find similar words

Now we have some interesting data to analyse! We can e.g. find pairs of Italian word which are similar to each other. Have you heard about Levenshtein distance? Google it. But we will use much simpler metric for measuring “distance” between words. We will consider only words with the same length and at the same time at least with 4 characters. Then we will count how many characters at the same positions are the same and that will be our measure of “similarity”. We will check all 1,000 x 1,000 pairs (!) and sort them according to the similarity measure.

Your task is to: get the list from the file “italian.txt”, put it into a list. Go through all possible pairs of words (minimum length is 4, word in pairs must have the same length) and measure the similarity, save the score into a new list, sort it and print out 10 most similar words (since there will be many many items in the list).

f = open("italian.txt")

words = []

for line in f:
word = line.strip()
if len(word) > 3:
words.append(word)

# here we will store the pairs and their distances
allPairs = []

# for all words
for i in range(len(words)):
word1 = words[i]
# again for all words => all pairs
for j in range(len(words)):
word2 = words[j]
# skip pairs abc-abc and also
# consider only abc-def and not def-abc
if i < j:
# only when the lengths are the same
if len(word1) == len(word2):
# number of the same characters
shared = 0
for k in range(len(word1)):
# check characters at the same positions
if word1[k] == word2[k]:
shared += 1
# triplets where the first item is the number
allPairs.append([shared, word1, word2])

# sort by the similarity number (first item in triplets)
allPairs.sort()
# the highest number ~ the most similar
allPairs.reverse()

# print out only the top 10 items
for i in range(10):
item = allPairs[i]
print(item[1], item[2], item[0])

print("All possible pairs: ", (len(words)*(len(words)-1))//2)
print("All considered pairs: ", len(allPairs))


text:
laminarskq2p

2023-02-24

The measure of an angle is five times its complement. The angle measures
(a) ${25}^{\circ }$
b) ${35}^{\circ }$
c) ${65}^{\circ }$
d) ${75}^{\circ }$

antipornofsc2

Let the measure of the required angle be x.
Then, the measure of its complement will be 90-x.
According to the question, we have the measure of angle
$⇒x=5\left(90-x\right)\phantom{\rule{0ex}{0ex}}⇒x=450-5x\phantom{\rule{0ex}{0ex}}⇒6x=450\phantom{\rule{0ex}{0ex}}\therefore x={75}^{\circ }$

Do you have a similar question?

format: plain


text:
Browse Questions

# A capacitor with air between its plates has a capacitance of $6uF$. What will be its capacitance if glass is substituted for air? Dielectric constant for glass is 6.

$\large\frac{C_1}{C_2}$$= N^{1/3}$


text:
# If a shaft is required to transmit twice the power at twice the speed for which it is designed, its diameter must

16 views
in General
closed
If a shaft is required to transmit twice the power at twice the speed for which it is designed, its diameter must
1. increase two times
2. reduce two times
3. remain same
4. increase three times

by (30.0k points)
selected

Correct Answer - Option 3 : remain same

Concept:

The power transmitting capacity of the shaft is given by

$P = \frac{{2\pi NT}}{{60}}$

P ∝ NT

Torsion equation:

$\frac{T}{J} = \frac{{{\tau _{max}}}}{R} = \frac{{G\theta }}{l}$

$T = {\tau _{max}} \times \frac{J}{R}$

$J = \frac{\pi }{{32}} \times {D^4}$

$T = \frac{{{\tau _{max}}\; \times \;\pi \; \times {D^3}\;}}{{16}}$

T ∝ D3

P ∝ NT

P ∝ ND3

Calculation:

Given:

P2 = 2P1, N2 = 2N1

$\frac{P_2}{P_1}=\frac{N_2}{N_1}\times\frac{D_2^3}{D_1^3}$

$\frac{2P_1}{P_1}=\frac{2N_1}{N_1}\times\frac{D_2^3}{D_1^3}$

D1 = D2


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# How Does Fracking and Nuclear Power Production Affect Water?

Energy production in America has some of the greatest impact on the environment. While the amount of carbon released into the atmosphere and the resulting issue of global warming are obvious contentions, another major issue is the sheer amount of water that needs to be used to produce energy. Two major sources of power production in the U.S. require massive amounts of water: fracking and nuclear. The result of both of these processes is the same as well, with millions of gallons of wastewater being created in the process. The question is, which process wastes more water?

There are over 500,000 active natural gas wells in the United States, with 70,000 in Pennsylvania alone. Generally, each well can be fracked up to 18 times. Considering that each frack uses about 5 million gallons of water, each well requires trillions of gallons of water during its lifetime.

$500,000 \text { wells} \times 5,000,000 \text { gal} \times 18 \text { fracks} = 45 \text { trillion gal}$

Nuclear power plants, conversely, are not as uniform in their water usage. There are 104 nuclear power plants in the United States. Of these plants, 60 percent utilize recirculating cooling. Thus, while freshwater is consumed, it is a very limited amount. The remaining 40 percent of nuclear plants, however, utilize once through cooling. This requires water to be drawn from a freshwater source daily. After treatment, the water is then released into the original freshwater source. Nuclear plants require about 1 billion gallons of water per day for cooling.

$40 \text { nuclear plants} \times 1 \text { billion gal} \times 365 \text { days} =14.6 \text { trillion gal}$

To put both of these amounts in context, New York City requires about a billion gallons of water per day, or 365 billion per year. Comparatively, fracking uses about 123 times this amount, while nuclear power plants require 40,000 times more water.

$1 \text { billion gal} \times 365 \text { days} = 365 \text { billion gal}$

$\frac {45 \text { trillion gal}}{365 \text { billion gal}} ≈123$

$\frac {14.6 \text { trillion gal}}{365 \text { billion gal}} =40$

So clearly, fracking uses far more water than nuclear power production. But what about the adverse effects of both methods of power production? Water used for the fracking of wells is almost completely wasted. Approximately 10-30 percent returns to the surface with the gas, while the rest remains in the ground and is absorbed. The water that returns to the surface is then either disposed of or treated. Many are concerned that poorly drilled wells that are too close to groundwater sources will leak into these groundwater sources, which are especially vital for people in rural areas.

Water used in nuclear power production is all reentered into the original freshwater source. However, the treatment process greatly heats the water, with water returning to the source at 30 degrees warmer than normal. This can harm aquatic life and destabilize the ecosystem.

In terms of carbon emissions, nuclear only emits 73 million tonnes of carbon dioxide, while natural gas emits 1256 million tonnes. Nuclear is far cleaner than natural gas, but natural gas is, in turn, far cleaner than coal and oil. This is why natural gas is looked upon as the ultimate transition fuel away from fossil fuels.

Both processes have their perks. Natural gas produced by fracking releases far less carbon into the air than coal or oil. Nuclear power plants, in turn, are nearly as clean as solar, wind, and hydroelectric plants. Despite the positives in terms of protecting the atmosphere, both sides of this issue require massive quantities of water, thus resulting in similarly large amounts of wastewater. These issues should be seriously considered by state governments before allowing the construction of new nuclear power plants or the fracking of new wells.

Works Cited:

“Explore Shale. Marcellus Shale Development, Geology and Water.” exploreshale.org. Penn State Public Broadcasting, 2016. Web. 22 Jan. 2016. <http://exploreshale.org/>.

“Greenhouse Gas Emissions Avoided through Use of Nuclear Energy.” World-nuclear.org. World Nuclear Association, 2016. Web. 18 Feb. 2016. <http://www.world-nuclear.org/nuclear-basics/greenhouse-gas-emissions-avoided.aspx>.

“History of Drought and Water Consumption.” Nyc.gov. City of New York, 2016. Web. 19 Feb. 2016. <http://www.nyc.gov/html/dep/html/drinking_water/droughthist.shtml>.

“Hydraulic Fracturing.” Hydraulic Fracturing. Marcellus Protest, 2016. Web. 19 Feb. 2016. <http://www.marcellusprotest.org/what-is-fracking>.

“Number of Producing Gas Wells.” Number of Producing Gas Wells. U.S. Energy Information Administration, 29 Jan. 2016. Web. 19 Feb. 2016. <https://www.eia.gov/dnav/ng/ng_prod_wells_s1_a.htm>.

“Quick Facts on Nuclear Power and Water Use.” Nuclear Power and Water 117.10 (2011): 148-49. Ucsusa.org. Union of Concerned Scientists, Dec. 2011. Web. 29 Jan. 2016. <http://www.ucsusa.org/sites/default/files/legacy/assets/documents/nuclear_power/fact-sheet-water-use.pdf>.

This entry was posted in Student Writing. Bookmark the permalink.


text:
Limited access

Accept the following two statements as true.

(1) $h^2-u=\cfrac{10}{u}$

(2) $-u>u+103$

Is there sufficient information from these statements to determine if $h$has a real value?

A

Statement (1) ALONE is sufficient to answer the question, but statement (2) ALONE is not.

B

Statement (2) ALONE is sufficient to answer the question, but statement (1) ALONE is not.

C

Statement (1) and (2) TOGETHER are sufficient to answer the question asked, but NEITHER statement ALONE is sufficient.

D

EITHER statement ALONE is sufficient to answer the question.

E

Statements (1) and (2) TOGETHER are NOT sufficient to answer the question asked - more relevant data is required.

Select an assignment template


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# Voltage Follower - OPAMP

I am going through an OPAMP Voltage follower/Buffer Circuit.

I have 1 question regarding this Voltage follower circuit using OP-AMP and 2 questions in general regarding OP-AMP:

1. Let's say my Vcc rails of the OP-AMP are +5V and 0V. And I am giving a constant Vin=2V to the Non-inverting terminal of the OP-AMP and the Output terminal of the OP-AMP is fedback to the Inverting terminal without any feedback resistance.

I know, since this is a voltage follower circuit, the Output voltage follows the input voltage until the input voltage hits the saturation voltage (Vcc) of the OP-AMP.

But how does the voltages start initially?

Like, at the start, the voltage at the output terminal is 0V and 0V is at the Inverting terminal as well. Now, we give the Vcc power to the OP-AMP and the Input voltage to the non-inverting terminal. Vcc=+5V. And Vin=2V. Since the voltage at the non-inverting terminal is greater than the voltage at the inverting terminal, in this case, 2V and 0V, the Output should go to the saturation voltage, right? (Assuming this OP-AMP has high enough gain say 10000) So, the output goes to 5V and then this 5V is fedback to the inverting terminal which then makes the output go to negative saturation and hence output 0V (as -Vcc = 0V)

Where am I going wrong with the Voltage follower operation? In my understanding, the output still swings from +Vcc to -Vcc only.

I can understand the circuit with the Help of Math and the equations of Gain and the resistors of Feedback and so on. But when understanding with the intuitive working, I am misunderstanding. Please tell me how this voltage follower works at the initial start-up and how the output follows the input without any math or equations.

1. The Ideal characteristic of OP-AMP is that the differential voltage between the input terminals is 0V.

But in the real world, we give different input voltages to the terminals so as to amplify the difference between them, right?

If an ideal OP-AMP maintains the differential voltage between the input as 0V, then the OP-AMP can't amplify the differential voltage between the terminals, right?

Isn't this contradictory to the actual purpose of the OP-AMP? What am I missing here?

Last question,

1. The OP-AMP has high input impedance and Low output impedance. This means that the OP-AMP input terminals does not have any input currents drawn from the source.

And Low output impedance means, that it can produces how much ever current the load requires? Is there a limitation of how much current the OP-AMP can source?

And the output current to the load comes from the +Vcc power terminals of the OP-AMP right? Is there a limitation to the amount of current the OP-AMP can provide?

• If you have time try to read this electronics.stackexchange.com/questions/441184/…
– G36
Apr 5, 2020 at 6:55
• The op-amp output will not jump from 0V to 5V instantaneously. It will take some time. There will be a voltage "ramp" at the output. Also, as the output voltage increases from 0V towards Vcc the differential voltage seen by the amplifier input (Vdif = V+ - V- ) will be smaller and smaller. For example, at time 0s we have Vout = 0V and Vdif = (2V - 0V) = 2V but at time = 1s we have Vout = 1V at the output and Vdif = 2V -1V = 1V and at time 1.5s we have Vout=1.5V and Vdiff = 2V-1.5=0.5V.
– G36
Apr 5, 2020 at 9:16
• And because the Vdiff is getting smaller and smaller the rate of change of an output voltage will also get smaller. I should pointed out that any output voltage larger than 2V will change the sign of a Vdiff voltage. And this will cause that the output voltage will stop increases and it will start to decreases into a negative direction towards Vee.
– G36
Apr 5, 2020 at 9:17
• And the circuit will reach the equilibrium when this equation is met Vo = AOL*(Vin - V-) (only one solution is possible). And for the Voltage follower, we have $$V_0 = \frac{A_{OL}}{1 +A_{OL}} \times V_{IN}$$ Where Aol is a opamp open-loop gain
– G36
Apr 5, 2020 at 9:23


text:
# zbMATH — the first resource for mathematics

## Zhang, Xiangxiong

Compute Distance To:
 Author ID: zhang.xiangxiong Published as: Zhang, X; Zhang, X.; Zhang, X. X.; Zhang, Xiangxiong
 Documents Indexed: 99 Publications since 1989
all top 5

#### Co-Authors

 2 single-authored 11 Shu, Chi-Wang 2 Hu, Jingwei 2 Li, Hao 1 Cai, Xiaofeng 1 Demanet, Laurent 1 Gallivan, Kyle A. 1 Huang, Wen 1 Li, Hao 1 Li, Hao 1 Liu, Yuanyuan 1 Ning, Jianguo 1 Poggie, Jonathan 1 Qiu, Jianxian 1 Shu, Ruiwen 1 Srinivasan, Sashank 1 Wang, Cheng 1 Xia, Yinhua 1 Xie, Shusen 1 Xing, Yulong 1 Zhang, Yifan
all top 5

#### Serials

 9 Journal of Computational Physics 6 Journal of Scientific Computing 3 SIAM Journal on Numerical Analysis 2 Numerische Mathematik 2 SIAM Journal on Scientific Computing 1 Mathematics of Computation 1 Proceedings of the Royal Society of London. Series A. Mathematical, Physical and Engineering Sciences
all top 5

#### Fields

 20 Numerical analysis (65-XX) 14 Partial differential equations (35-XX) 12 Fluid mechanics (76-XX) 2 Calculus of variations and optimal control; optimization (49-XX) 1 Classical thermodynamics, heat transfer (80-XX) 1 Statistical mechanics, structure of matter (82-XX) 1 Operations research, mathematical programming (90-XX)

#### Citations contained in zbMATH

61 Publications have been cited 1,021 times in 563 Documents Cited by Year
On maximum-principle-satisfying high order schemes for scalar conservation laws. Zbl 1187.65096
Zhang, Xiangxiong; Shu, Chi-Wang
2010
On positivity-preserving high order discontinuous Galerkin schemes for compressible Euler equations on rectangular meshes. Zbl 1282.76128
Zhang, Xiangxiong; Shu, Chi-Wang
2010
Maximum-principle-satisfying and positivity-preserving high-order schemes for conservation laws: survey and new developments. Zbl 1222.65107
Zhang, Xiangxiong; Shu, Chi-Wang
2011
Maximum-principle-satisfying and positivity-preserving high order discontinuous Galerkin schemes for conservation laws on triangular meshes. Zbl 1247.65131
Zhang, Xiangxiong; Xia, Yinhua; Shu, Chi-Wang
2012
Positivity-preserving high order discontinuous Galerkin schemes for compressible Euler equations with source terms. Zbl 1391.76375
Zhang, Xiangxiong; Shu, Chi-Wang
2011
Positivity-preserving high order finite difference WENO schemes for compressible Euler equations. Zbl 1426.76493
Zhang, Xiangxiong; Shu, Chi-Wang
2012
Robust high order discontinuous Galerkin schemes for two-dimensional gaseous detonations. Zbl 1243.80011
Wang, Cheng; Zhang, Xiangxiong; Shu, Chi-Wang; Ning, Jianguo
2012
Maximum-principle-satisfying second order discontinuous Galerkin schemes for convection-diffusion equations on triangular meshes. Zbl 1284.65140
Zhang, Yifan; Zhang, Xiangxiong; Shu, Chi-Wang
2013
Positivity-preserving well-balanced discontinuous Galerkin methods for the shallow water equations on unstructured triangular meshes. Zbl 1282.76134
Xing, Yulong; Zhang, Xiangxiong
2013
Inclusions and inhomogeneities in strain gradient elasticity with couple stresses and related problems. Zbl 1119.74334
Zhang, X.; Sharma, P.
2005
A genuinely high order total variation diminishing scheme for one-dimensional scalar conservation laws. Zbl 1226.65083
Zhang, Xiangxiong; Shu, Chi-Wang
2010
Nonlinear deformation and breakup of stretching liquid bridges. Zbl 0899.76133
Zhang, X.; Padgett, R. S.; Basaran, O. A.
1996
A minimum entropy principle of high order schemes for gas dynamics equations. Zbl 1426.76444
Zhang, Xiangxiong; Shu, Chi-Wang
2012
A simulated annealing and hill-climbing algorithm for the traveling tournament problem. Zbl 1103.90042
Lim, A.; Rodrigues, B.; Zhang, X.
2006
Eventual linear convergence of the Douglas-Rachford iteration for basis pursuit. Zbl 1329.49050
Demanet, Laurent; Zhang, Xiangxiong
2016
An atomistic and non-classical continuum field theoretic perspective of elastic interactions between defects (force dipoles) of various symmetries and application to graphene. Zbl 1120.74315
Zhang, X.; Jiao, K.; Sharma, P.; Yakobson, B. I.
2006
Global stabilization of a class of time-delay nonlinear systems. Zbl 1121.93065
Zhang, X.; Cheng, Z.
2005
Global asymptotic stabilization of feedforward nonlinear systems with a delay in the input. Zbl 1120.93048
Zhang, X.; Gao, Hongyan; Zhang, C.
2006
Maximum-principle-satisfying high order finite volume weighted essentially nonoscillatory schemes for convection-diffusion equations. Zbl 1252.65146
Zhang, Xiangxiong; Liu, Yuanyuan; Shu, Chi-Wang
2012
A meshless, compositional approach to shape optimal design. Zbl 1173.74371
Zhang, X.; Rayasam, M.; Subbarayan, G.
2007
Meshless Galerkin least-squares method. Zbl 1143.74390
Pan, X. F.; Zhang, X.; Lu, M. W.
2005
Asymptotic-preserving and positivity-preserving implicit-explicit schemes for the stiff BGK equation. Zbl 1388.82023
Hu, Jingwei; Shu, Ruiwen; Zhang, Xiangxiong
2018
On positivity-preserving high order discontinuous Galerkin schemes for compressible Navier-Stokes equations. Zbl 1406.65091
Zhang, Xiangxiong
2017
Experimental NMR realization of a generalized quantum search algorithm. Zbl 0969.81513
Long, G. L.; Yan, H. Y.; Li, Y. S.; Tu, C. C.; Tao, J. X.; Chen, H. M.; Liu, M. L.; Zhang, X.; Luo, J.; Xiao, L.; Zeng, X. Z.
2001
Solving phaselift by low-rank Riemannian optimization methods for complex semidefinite constraints. Zbl 1373.65044
Huang, Wen; Gallivan, K. A.; Zhang, Xiangxiong
2017
Positivity-preserving high order finite volume HWENO schemes for compressible Euler equations. Zbl 1397.76084
Cai, Xiaofeng; Zhang, Xiangxiong; Qiu, Jianxian
2016
A curved boundary treatment for discontinuous Galerkin schemes solving time dependent problems. Zbl 1352.65380
Zhang, Xiangxiong
2016
Portfolio selection under DEA-based relative financial strength indicators: Case of US industries. Zbl 1153.90454
Edirisinghe, N. C. P.; Zhang, X.
2008
Scheduling sports competitions at multiple venues – revisited. Zbl 1137.90504
Lim, A.; Rodrigues, B.; Zhang, X.
2006
Skin friction and heat transfer in power-law fluid laminar boundary layer along a moving surface. Zbl 1101.76323
Zheng, L. C.; Zhang, X. X.
2002
Bound-preserving high-order schemes. Zbl 1368.65149
Xu, Z.; Zhang, X.
2017
Unsteady simulations of the flow around a short surface-mounted cylinder. Zbl 1235.76085
Pattenden, R. J.; Bressloff, N. W.; Turnock, S. R.; Zhang, X.
2007
Coarse grain parallel finite element simulations for incompressible flows. Zbl 0923.76113
Grant, P. W.; Webster, M. F.; Zhang, X.
1998
Improved coupling of finite element method with material point method based on a particle-to-surface contact algorithm. Zbl 1423.74870
Chen, Z. P.; Qiu, X. M.; Zhang, X.; Lian, Y. P.
2015
A mesh-grading material point method and its parallelization for problems with localized extreme deformation. Zbl 1423.74901
Lian, Y. P.; Yang, P. F.; Zhang, X.; Zhang, F.; Liu, Y.; Huang, P.
2015
3-D numerical analysis of natural convective liquid cooling of a $$3\times 3$$ heater array in rectangular enclosures. Zbl 0973.76610
Tou, S. K. W.; Tso, C. P.; Zhang, X.
1999
Some advances in the analysis of fluid flows. Zbl 0918.76035
Bathe, K. J.; Zhang, H.; Zhang, X.
1997
A positivity-preserving high order discontinuous Galerkin scheme for convection-diffusion equations. Zbl 1406.65090
Srinivasan, Sashank; Poggie, Jonathan; Zhang, Xiangxiong
2018
Quasi-finite-time control for high-order nonlinear systems with mismatched disturbances via mapping filtered forwarding technique. Zbl 1358.93142
Zhang, X.; Huang, X. L.; Lu, H. Q.
2017
A coupled finite difference material point method and its application in explosion simulation. Zbl 1356.80062
Cui, X. X.; Zhang, X.; Zhou, X.; Liu, Y.; Zhang, F.
2014
Input/output selection in DEA under expert information, with application to financial markets. Zbl 1206.91019
Edirisinghe, N. C. P.; Zhang, X.
2010
Time accurate numerical study of turbulent supersonic jets. Zbl 1236.76048
Rona, A.; Zhang, X.
2004
Geometry effects on flow transition in multilouvered fins – onset, propagation, and characteristic frequencies. Zbl 1091.76508
Tafti, D. K.; Zhang, X.
2001
Classification and effects of thermal wakes on heat transfer in multilouvered fins. Zbl 0983.76500
Zhang, X.; Tafti, D. K.
2001
Density and gradient estimates for non degenerate Brownian SDEs with unbounded measurable drift. Zbl 07285692
Menozzi, S.; Pesce, A.; Zhang, X.
2021
Constructing likelihood functions for interval-valued random variables. Zbl 1444.62139
Zhang, X.; Beranger, B.; Sisson, S. A.
2020
Superconvergence of high order finite difference schemes based on variational formulation for elliptic equations. Zbl 1434.65268
Li, Hao; Zhang, Xiangxiong
2020
Superconvergence of $$C^0-Q^k$$ finite element method for elliptic equations with approximated coefficients. Zbl 1434.65267
Li, Hao; Zhang, Xiangxiong
2020
On natural modes in moonpools and gaps in finite depth. Zbl 1419.76346
Molin, Bernard; Zhang, X.; Huang, H.; Remy, F.
2018
A high order accurate bound-preserving compact finite difference scheme for scalar convection diffusion equations. Zbl 1405.65097
Li, Hao; Xie, Shusen; Zhang, Xiangxiong
2018
On a class of implicit-explicit Runge-Kutta schemes for stiff kinetic equations preserving the Navier-Stokes limit. Zbl 1382.35179
Hu, Jingwei; Zhang, Xiangxiong
2017
A delay-range-partition approach to analyse stability of linear systems with time-varying delays. Zbl 1346.93305
Xue, Y.; Zhang, X.; Han, Y. Y.; Shi, M.
2016
Dynamical Casimir-polder force in a cavity comprising a dielectric with output coupling. Zbl 1295.81123
Yang, H.; Zheng, T. Y.; Shao, X. Q.; Zhang, X.; Pan, S. M.
2013
Improved modification direction methods. Zbl 1198.94029
Kim, H. J.; Kim, C.; Choi, Y.; Wang, S.; Zhang, X.
2010
Equipment scheduling problem under disruptions in mail processing and distribution centres. Zbl 1171.90413
Zhang, X.; Chakravarthy, A.; Gu, Q.
2009
Quantum dot-DNA interaction: Computational issues and preliminary insights on use of quantum dots as biosensors. Zbl 1162.92007
Anandampillai, S.; Zhang, X.; Sharma, P.; Lynch, Gillian C.; Franchek, M. A.; Larin, K. V.
2008
Impact of weak localization on wave dynamics: crossover from quasi-1D to slab geometry. Zbl 1092.81028
Zhang, Z. Q.; Cheung, S. K.; Zhang, X.; Chabanov, A. A.; Genack, A. Z.
2004
An exact method for penny-shaped cracked homogeneous and composite cylinders. Zbl 1005.74056
Xie, Y. J.; Zhang, X.; Wang, X. H.
2001
Nonlinear control of a planar multiaxis servohydraulic test facility using exact linearization techniques. Zbl 0829.70019
Hahn, H.; Zhang, X.; Leimbach, K.-D.; Sommer, H.-J.
1994
An appraisal of different stochastic linearization techniques. Zbl 0925.70298
Elishakoff, I.; Zhang, X.
1992
The solution of stress intensity factor for mode II cracking in orthotropic cracked plate by complex variable-variational method. Zbl 0731.73063
Cui, D.; Zhang, X.
1991
Density and gradient estimates for non degenerate Brownian SDEs with unbounded measurable drift. Zbl 07285692
Menozzi, S.; Pesce, A.; Zhang, X.
2021
Constructing likelihood functions for interval-valued random variables. Zbl 1444.62139
Zhang, X.; Beranger, B.; Sisson, S. A.
2020
Superconvergence of high order finite difference schemes based on variational formulation for elliptic equations. Zbl 1434.65268
Li, Hao; Zhang, Xiangxiong
2020
Superconvergence of $$C^0-Q^k$$ finite element method for elliptic equations with approximated coefficients. Zbl 1434.65267
Li, Hao; Zhang, Xiangxiong
2020
Asymptotic-preserving and positivity-preserving implicit-explicit schemes for the stiff BGK equation. Zbl 1388.82023
Hu, Jingwei; Shu, Ruiwen; Zhang, Xiangxiong
2018
A positivity-preserving high order discontinuous Galerkin scheme for convection-diffusion equations. Zbl 1406.65090
Srinivasan, Sashank; Poggie, Jonathan; Zhang, Xiangxiong
2018
On natural modes in moonpools and gaps in finite depth. Zbl 1419.76346
Molin, Bernard; Zhang, X.; Huang, H.; Remy, F.
2018
A high order accurate bound-preserving compact finite difference scheme for scalar convection diffusion equations. Zbl 1405.65097
Li, Hao; Xie, Shusen; Zhang, Xiangxiong
2018
On positivity-preserving high order discontinuous Galerkin schemes for compressible Navier-Stokes equations. Zbl 1406.65091
Zhang, Xiangxiong
2017
Solving phaselift by low-rank Riemannian optimization methods for complex semidefinite constraints. Zbl 1373.65044
Huang, Wen; Gallivan, K. A.; Zhang, Xiangxiong
2017
Bound-preserving high-order schemes. Zbl 1368.65149
Xu, Z.; Zhang, X.
2017
Quasi-finite-time control for high-order nonlinear systems with mismatched disturbances via mapping filtered forwarding technique. Zbl 1358.93142
Zhang, X.; Huang, X. L.; Lu, H. Q.
2017
On a class of implicit-explicit Runge-Kutta schemes for stiff kinetic equations preserving the Navier-Stokes limit. Zbl 1382.35179
Hu, Jingwei; Zhang, Xiangxiong
2017
Eventual linear convergence of the Douglas-Rachford iteration for basis pursuit. Zbl 1329.49050
Demanet, Laurent; Zhang, Xiangxiong
2016
Positivity-preserving high order finite volume HWENO schemes for compressible Euler equations. Zbl 1397.76084
Cai, Xiaofeng; Zhang, Xiangxiong; Qiu, Jianxian
2016
A curved boundary treatment for discontinuous Galerkin schemes solving time dependent problems. Zbl 1352.65380
Zhang, Xiangxiong
2016
A delay-range-partition approach to analyse stability of linear systems with time-varying delays. Zbl 1346.93305
Xue, Y.; Zhang, X.; Han, Y. Y.; Shi, M.
2016
Improved coupling of finite element method with material point method based on a particle-to-surface contact algorithm. Zbl 1423.74870
Chen, Z. P.; Qiu, X. M.; Zhang, X.; Lian, Y. P.
2015
A mesh-grading material point method and its parallelization for problems with localized extreme deformation. Zbl 1423.74901
Lian, Y. P.; Yang, P. F.; Zhang, X.; Zhang, F.; Liu, Y.; Huang, P.
2015
A coupled finite difference material point method and its application in explosion simulation. Zbl 1356.80062
Cui, X. X.; Zhang, X.; Zhou, X.; Liu, Y.; Zhang, F.
2014
Maximum-principle-satisfying second order discontinuous Galerkin schemes for convection-diffusion equations on triangular meshes. Zbl 1284.65140
Zhang, Yifan; Zhang, Xiangxiong; Shu, Chi-Wang
2013
Positivity-preserving well-balanced discontinuous Galerkin methods for the shallow water equations on unstructured triangular meshes. Zbl 1282.76134
Xing, Yulong; Zhang, Xiangxiong
2013
Dynamical Casimir-polder force in a cavity comprising a dielectric with output coupling. Zbl 1295.81123
Yang, H.; Zheng, T. Y.; Shao, X. Q.; Zhang, X.; Pan, S. M.
2013
Maximum-principle-satisfying and positivity-preserving high order discontinuous Galerkin schemes for conservation laws on triangular meshes. Zbl 1247.65131
Zhang, Xiangxiong; Xia, Yinhua; Shu, Chi-Wang
2012
Positivity-preserving high order finite difference WENO schemes for compressible Euler equations. Zbl 1426.76493
Zhang, Xiangxiong; Shu, Chi-Wang
2012
Robust high order discontinuous Galerkin schemes for two-dimensional gaseous detonations. Zbl 1243.80011
Wang, Cheng; Zhang, Xiangxiong; Shu, Chi-Wang; Ning, Jianguo
2012
A minimum entropy principle of high order schemes for gas dynamics equations. Zbl 1426.76444
Zhang, Xiangxiong; Shu, Chi-Wang
2012
Maximum-principle-satisfying high order finite volume weighted essentially nonoscillatory schemes for convection-diffusion equations. Zbl 1252.65146
Zhang, Xiangxiong; Liu, Yuanyuan; Shu, Chi-Wang
2012
Maximum-principle-satisfying and positivity-preserving high-order schemes for conservation laws: survey and new developments. Zbl 1222.65107
Zhang, Xiangxiong; Shu, Chi-Wang
2011
Positivity-preserving high order discontinuous Galerkin schemes for compressible Euler equations with source terms. Zbl 1391.76375
Zhang, Xiangxiong; Shu, Chi-Wang
2011
On maximum-principle-satisfying high order schemes for scalar conservation laws. Zbl 1187.65096
Zhang, Xiangxiong; Shu, Chi-Wang
2010
On positivity-preserving high order discontinuous Galerkin schemes for compressible Euler equations on rectangular meshes. Zbl 1282.76128
Zhang, Xiangxiong; Shu, Chi-Wang
2010
A genuinely high order total variation diminishing scheme for one-dimensional scalar conservation laws. Zbl 1226.65083
Zhang, Xiangxiong; Shu, Chi-Wang
2010
Input/output selection in DEA under expert information, with application to financial markets. Zbl 1206.91019
Edirisinghe, N. C. P.; Zhang, X.
2010
Improved modification direction methods. Zbl 1198.94029
Kim, H. J.; Kim, C.; Choi, Y.; Wang, S.; Zhang, X.
2010
Equipment scheduling problem under disruptions in mail processing and distribution centres. Zbl 1171.90413
Zhang, X.; Chakravarthy, A.; Gu, Q.
2009
Portfolio selection under DEA-based relative financial strength indicators: Case of US industries. Zbl 1153.90454
Edirisinghe, N. C. P.; Zhang, X.
2008
Quantum dot-DNA interaction: Computational issues and preliminary insights on use of quantum dots as biosensors. Zbl 1162.92007
Anandampillai, S.; Zhang, X.; Sharma, P.; Lynch, Gillian C.; Franchek, M. A.; Larin, K. V.
2008
A meshless, compositional approach to shape optimal design. Zbl 1173.74371
Zhang, X.; Rayasam, M.; Subbarayan, G.
2007
Unsteady simulations of the flow around a short surface-mounted cylinder. Zbl 1235.76085
Pattenden, R. J.; Bressloff, N. W.; Turnock, S. R.; Zhang, X.
2007
A simulated annealing and hill-climbing algorithm for the traveling tournament problem. Zbl 1103.90042
Lim, A.; Rodrigues, B.; Zhang, X.
2006
An atomistic and non-classical continuum field theoretic perspective of elastic interactions between defects (force dipoles) of various symmetries and application to graphene. Zbl 1120.74315
Zhang, X.; Jiao, K.; Sharma, P.; Yakobson, B. I.
2006
Global asymptotic stabilization of feedforward nonlinear systems with a delay in the input. Zbl 1120.93048
Zhang, X.; Gao, Hongyan; Zhang, C.
2006
Scheduling sports competitions at multiple venues – revisited. Zbl 1137.90504
Lim, A.; Rodrigues, B.; Zhang, X.
2006
Inclusions and inhomogeneities in strain gradient elasticity with couple stresses and related problems. Zbl 1119.74334
Zhang, X.; Sharma, P.
2005
Global stabilization of a class of time-delay nonlinear systems. Zbl 1121.93065
Zhang, X.; Cheng, Z.
2005
Meshless Galerkin least-squares method. Zbl 1143.74390
Pan, X. F.; Zhang, X.; Lu, M. W.
2005
Time accurate numerical study of turbulent supersonic jets. Zbl 1236.76048
Rona, A.; Zhang, X.
2004
Impact of weak localization on wave dynamics: crossover from quasi-1D to slab geometry. Zbl 1092.81028
Zhang, Z. Q.; Cheung, S. K.; Zhang, X.; Chabanov, A. A.; Genack, A. Z.
2004
Skin friction and heat transfer in power-law fluid laminar boundary layer along a moving surface. Zbl 1101.76323
Zheng, L. C.; Zhang, X. X.
2002
Experimental NMR realization of a generalized quantum search algorithm. Zbl 0969.81513
Long, G. L.; Yan, H. Y.; Li, Y. S.; Tu, C. C.; Tao, J. X.; Chen, H. M.; Liu, M. L.; Zhang, X.; Luo, J.; Xiao, L.; Zeng, X. Z.
2001
Geometry effects on flow transition in multilouvered fins – onset, propagation, and characteristic frequencies. Zbl 1091.76508
Tafti, D. K.; Zhang, X.
2001
Classification and effects of thermal wakes on heat transfer in multilouvered fins. Zbl 0983.76500
Zhang, X.; Tafti, D. K.
2001
An exact method for penny-shaped cracked homogeneous and composite cylinders. Zbl 1005.74056
Xie, Y. J.; Zhang, X.; Wang, X. H.
2001
3-D numerical analysis of natural convective liquid cooling of a $$3\times 3$$ heater array in rectangular enclosures. Zbl 0973.76610
Tou, S. K. W.; Tso, C. P.; Zhang, X.
1999
Coarse grain parallel finite element simulations for incompressible flows. Zbl 0923.76113
Grant, P. W.; Webster, M. F.; Zhang, X.
1998
Some advances in the analysis of fluid flows. Zbl 0918.76035
Bathe, K. J.; Zhang, H.; Zhang, X.
1997
Nonlinear deformation and breakup of stretching liquid bridges. Zbl 0899.76133
Zhang, X.; Padgett, R. S.; Basaran, O. A.
1996
Nonlinear control of a planar multiaxis servohydraulic test facility using exact linearization techniques. Zbl 0829.70019
Hahn, H.; Zhang, X.; Leimbach, K.-D.; Sommer, H.-J.
1994
An appraisal of different stochastic linearization techniques. Zbl 0925.70298
Elishakoff, I.; Zhang, X.
1992
The solution of stress intensity factor for mode II cracking in orthotropic cracked plate by complex variable-variational method. Zbl 0731.73063
Cui, D.; Zhang, X.
1991
all top 5

#### Cited by 1,038 Authors

 52 Shu, Chi-Wang 17 Zhang, Xiangxiong 14 Qiu, Jingmei 11 Qiu, Jianxian 11 Xu, Zhengfu 8 Basaran, Osman A. 7 Christlieb, Andrew J. 7 Martínez Gamba, Irene 7 Gao, Zhen 7 Kuzmin, Dmitri 7 Loubère, Raphaël 7 Schneider, Florian H. 7 Wu, Kailiang 7 Xiong, Tao 7 Zhang, Mengping 7 Zhang, Xianfu 6 Don, Wai Sun 6 Du, Jie 6 Hauck, Cory D. 6 Xing, Yulong 5 Capdeville, Guy 5 Cheng, Juan 5 Cheng, Yingda 5 Fadili, Jalal M. 5 Frank, Martin 5 Guermond, Jean-Luc 5 Ihme, Matthias 5 Liu, Hailiang 5 Lv, Yu 5 Marche, Fabien 5 Peyré, Gabriel 5 Seal, David C. 5 Tang, Qi 5 Xia, Yinhua 4 Alldredge, Graham W. 4 Cai, Xiaofeng 4 Chandrashekar, Praveen 4 Duran, Arnaud 4 Guo, Wei 4 Huang, Juntao 4 Huang, Weizhang 4 Huang, Wen 4 Li, Fengyan 4 Liang, Jingwei 4 Lin, Shih-Wei 4 Liu, Qingrong 4 Liu, Yuan 4 Maire, Pierre-Henri 4 Myong, Rho-Shin 4 Pepe, Pierdomenico 4 Popov, Boyan 4 Shi, Yufeng 4 Subbarayan, Ganesh 4 Tang, Huazhong 4 Zhu, Hongqiang 3 Absil, Pierre-Antoine 3 Afraimovich, L. G. 3 Aizinger, Vadym 3 Ambravaneswaran, Balasubramanian 3 Bauschke, Heinz H. 3 Bello Cruz, Jose Yunier 3 Biswas, Biswarup 3 Bui-Thanh, Tan 3 Choi, Ho-Lim 3 Delfani, M. R. 3 Deng, Xi 3 Diot, Steven 3 Dubey, Ritesh Kumar 3 Dumbser, Michael 3 Gallivan, Kyle A. 3 Guo, Yan 3 Han, Wenhu 3 Ketcheson, David I. 3 Kim, Hyun Jung 3 Kolev, Tzanio V. 3 Kumar, Rakesh 3 Li, Maojun 3 Ling, Dan 3 Ma, Huimin 3 Perrier, Vincent 3 Ranocha, Hendrik 3 Rieben, Robert N. 3 Rossmanith, James A. 3 Seo, Yu-Deok 3 Shu, Ruiwen 3 Xiao, Feng 3 Yang, Yang 3 Yang, Yang 3 Yang, Yang 3 Youn, Sung-Kie 3 Yu, Vincent F. 3 Zhang, Chenghui 2 Abbaszadeh, Mostafa 2 Adams, Nikolaus A. 2 Akkerman, Ido 2 Augarde, Charles Edward 2 Baloch, A. 2 Baron, Luc 2 Behling, Roger 2 Benabdallah, Amel ...and 938 more Authors
all top 5

#### Cited in 122 Serials

 121 Journal of Computational Physics 55 Journal of Scientific Computing 35 Computers and Fluids 33 Computer Methods in Applied Mechanics and Engineering 24 SIAM Journal on Scientific Computing 12 SIAM Journal on Numerical Analysis 11 Applied Mathematics and Computation 10 Journal of Fluid Mechanics 9 European Journal of Operational Research 9 Physics of Fluids 8 Acta Mechanica 8 Computers & Mathematics with Applications 8 Journal of Computational and Applied Mathematics 8 European Journal of Mechanics. A. Solids 7 International Journal of Solids and Structures 6 International Journal of Heat and Mass Transfer 6 Numerische Mathematik 6 Applied Numerical Mathematics 6 Applied Mathematical Modelling 6 Engineering Analysis with Boundary Elements 5 Journal of the Mechanics and Physics of Solids 5 Mathematics of Computation 5 Systems & Control Letters 5 M$$^3$$AS. Mathematical Models & Methods in Applied Sciences 4 Automatica 4 Computers & Operations Research 4 Mathematics and Mechanics of Solids 4 Quantum Information Processing 3 International Journal of Control 3 Journal of Optimization Theory and Applications 3 Annals of Operations Research 3 Automation and Remote Control 3 International Journal of Robust and Nonlinear Control 3 SIAM Journal on Optimization 3 Mathematical Problems in Engineering 3 European Journal of Mechanics. B. Fluids 3 International Journal of Systems Science. Principles and Applications of Systems and Integration 2 International Journal of Engineering Science 2 International Journal of Systems Science 2 Journal of the Franklin Institute 2 Mathematical Methods in the Applied Sciences 2 BIT 2 International Journal for Numerical Methods in Engineering 2 Numerical Methods for Partial Differential Equations 2 Numerical Algorithms 2 Journal of Elasticity 2 Journal of Non-Newtonian Fluid Mechanics 2 Advances in Computational Mathematics 2 Nonlinear Dynamics 2 Communications in Nonlinear Science and Numerical Simulation 2 Computational Geosciences 2 Sādhanā 2 International Journal of Computational Methods 2 Discrete Optimization 2 Acta Mechanica Sinica 2 AMM. Applied Mathematics and Mechanics. (English Edition) 1 Modern Physics Letters B 1 International Journal of Modern Physics B 1 International Journal of Theoretical Physics 1 Journal of Mathematical Analysis and Applications 1 Reviews of Modern Physics 1 Ukrainian Mathematical Journal 1 Wave Motion 1 ZAMP. Zeitschrift für angewandte Mathematik und Physik 1 Shock Waves 1 Journal of Approximation Theory 1 Journal of Differential Equations 1 Kybernetika 1 Meccanica 1 Operations Research Letters 1 Circuits, Systems, and Signal Processing 1 Bulletin of the Iranian Mathematical Society 1 Optimization 1 Computational Mechanics 1 Mathematical and Computer Modelling 1 SIAM Journal on Matrix Analysis and Applications 1 International Journal of Adaptive Control and Signal Processing 1 Annals of Physics 1 SIAM Journal on Applied Mathematics 1 Mathematical Programming. Series A. Series B 1 Archive of Applied Mechanics 1 Computational Optimization and Applications 1 Computational and Applied Mathematics 1 International Journal of Numerical Methods for Heat & Fluid Flow 1 Complexity 1 Journal of Heuristics 1 Parallel Algorithms and Applications 1 Differential Equations and Dynamical Systems 1 Journal of Inequalities and Applications 1 Journal of Scheduling 1 ZAMM. Zeitschrift für Angewandte Mathematik und Mechanik 1 Chaos 1 Proceedings of the Royal Society of London. Series A. Mathematical, Physical and Engineering Sciences 1 Flow, Turbulence and Combustion 1 Engineering Computations 1 International Journal of Nonlinear Sciences and Numerical Simulation 1 Journal of Systems Science and Complexity 1 Journal of Applied Mathematics 1 Bulletin of the Brazilian Mathematical Society. New Series 1 Multiscale Modeling & Simulation ...and 22 more Serials
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#### Cited in 36 Fields

 329 Numerical analysis (65-XX) 239 Fluid mechanics (76-XX) 167 Partial differential equations (35-XX) 76 Mechanics of deformable solids (74-XX) 53 Operations research, mathematical programming (90-XX) 35 Systems theory; control (93-XX) 28 Statistical mechanics, structure of matter (82-XX) 23 Classical thermodynamics, heat transfer (80-XX) 16 Biology and other natural sciences (92-XX) 14 Calculus of variations and optimal control; optimization (49-XX) 13 Computer science (68-XX) 13 Geophysics (86-XX) 8 Ordinary differential equations (34-XX) 8 Quantum theory (81-XX) 7 Astronomy and astrophysics (85-XX) 6 Operator theory (47-XX) 5 Dynamical systems and ergodic theory (37-XX) 5 Probability theory and stochastic processes (60-XX) 4 Game theory, economics, finance, and other social and behavioral sciences (91-XX) 3 Approximations and expansions (41-XX) 3 Integral equations (45-XX) 3 Statistics (62-XX) 3 Optics, electromagnetic theory (78-XX) 3 Relativity and gravitational theory (83-XX) 2 Combinatorics (05-XX) 2 Harmonic analysis on Euclidean spaces (42-XX) 2 Mechanics of particles and systems (70-XX) 2 Information and communication theory, circuits (94-XX) 1 Number theory (11-XX) 1 Linear and multilinear algebra; matrix theory (15-XX) 1 Real functions (26-XX) 1 Difference and functional equations (39-XX) 1 Integral transforms, operational calculus (44-XX) 1 Functional analysis (46-XX) 1 Differential geometry (53-XX) 1 Global analysis, analysis on manifolds (58-XX)


text:
Notes On History of Periodic Table - CBSE Class 10 Science
The earliest classification categorized elements into metals and non-metals. It was difficult to classify the elements, such as boron, which exhibited the properties of both metals as well as non-metals. After further research a German scientist, Dobereiner arrived at a hypothesis in the year 1829. According to Dobereiner, all elements occurred in groups of three, when arranged in increasing order of atomic masses. He referred to these groups as triads. In a traid the elements had similar chemical properties.  Traids of the Dobereiners classification: Traid1: Element Atomic mass Lithium  (Li) 7 Sodium (Na) 23 Potassium (K) 39 Traid2: Element Atomic mass Chlorine (Cl) 35.5 Bromine (Br) 80 Iodine (I) 127 Traid3: Element Atomic mass Calcium (Ca) 40 Strontium (Sr) 88 Barium (Ba) 137 Dobereiner’s law of triads states that, the atomic mass of the middle element of a triad is the arithmetic mean of the atomic masses of the other two elements.   Example: In the triad of lithium, sodium and potassium. The atomic mass of lithium is 7 and  the atomic mass of potassium is 39. The average of masses of lithium and potassium gives atomic mass of sodium 23.  Drawbacks: All the known elements could not be arranged in the form of triads. This law did not hold good for elements with very low or very high atomic mass.  Example: The arithmetic mean of the atomic masses of fluorine 19 and bromine 80, which comes to 49.5, varies significantly from the atomic mass of chlorine, which is 35.5.  Since Dobereiner’s law could not successfully group elements, the attempts at classification continued. The next attempt came in 1864, when an English chemist, John Newlands, stated his observations in the form of Newlands Law of Octaves. Newlands Law of Octaves: When Newlands arranged elements in according to their atomic weights then there was similarity of every eighth element. Newland described it as "law of octaves". According to this law every eighth element is similar to that of the first element, similar to the first and the eighth notes in the musical scale.  Newlands classification of elements: Li Be B C N O F Na Mg Al Si P S Cl K Ca Example: When starting from lithium, the eighth element is sodium. Similarly, the eighth element from sodium is potassium. Lithium, sodium and potassium show similar properties. Drawbacks: Not valid for elements having atomic masses higher than calcium. Newly discovered elements could not find a place in Newlands table. Mendeleev's periodic table: Mendeleev based his work on the research by Newlands and took it further. He felt that effective grouping of elements and prediction of properties could be based on two parameters: Atomic mass  Chemical reactivity Mendeleev’s periodic law states that "the physical and chemical properties of all elements are the periodic function of their atomic masses".   Row  Group I  Group II  Group III  Group IV  Group V  Group VI  Group VII  Group VIII  1  2  3 H = 1 Li = 7 Na = 23 Be = 9 Mg = 24 B = 11 Al = 27 C = 12 Si = 28 N = 14 P = 31 O = 16 S = 32 F = 19 Cl = 35.5  4  5 K = 39 Cu = 63 Ca = 40 Zn = 65 Ti = 48 V = 51 As = 75 Cr = 52 Se = 79 Mn = 35 Br = 80 Fe = 56 Co = 58.94 Ni = 58.68  6  7 Rb = 85 Ag = 108 Sr = 87 Cd = 112 Y = 89 In = 113 Zr = 90 Sn = 118 Nb = 94 Sb = 120 Mo = 96 Te = 128 I = 127 Ru = 103 Rh = 104 Pd = 106  8  9 Cs = 133 Ba = 137 La = 138 Ce = 140  10  11 Au = 198 Hg = 200 Yb = 173 Tl = 204 Pb = 206 Ta = 182 Bi = 208 W = 184 Os = 191 Ir =193 Pt = 196  12  Th = 232  U = 240 The main features of Mendeleev’s periodic table: The known 63 elements were classified into groups and periods. The table had 8 vertical columns called groups and 12 horizontal rows called periods. In every group, a gradation of physical and chemical properties of elements was observed. The table provided gaps for undiscovered elements. The table helped to predict the properties of three unknown elements of that time. These elements were named eka-boron, eka-aluminium and eka-silicon. When these elements were discovered, they were named scandium, gallium and germanium. The properties of these elements were very close to those predicted by Mendeleev. Merits: The table helped in the correction of atomic mass for many elements. It predicted the existence of some elements that have not been discovered at the time the table was created. Demerits: The atomic weights of two pairs of elements were reversed.  Alkali metals and coinage metals were placed in the same group.  Lanthanides and actinides were not given proper place in the periodic table.  Isotopes were not placed in the periodic table.  The position of hydrogen was not clearly discussed

#### Summary

The earliest classification categorized elements into metals and non-metals. It was difficult to classify the elements, such as boron, which exhibited the properties of both metals as well as non-metals. After further research a German scientist, Dobereiner arrived at a hypothesis in the year 1829. According to Dobereiner, all elements occurred in groups of three, when arranged in increasing order of atomic masses. He referred to these groups as triads. In a traid the elements had similar chemical properties.  Traids of the Dobereiners classification: Traid1: Element Atomic mass Lithium  (Li) 7 Sodium (Na) 23 Potassium (K) 39 Traid2: Element Atomic mass Chlorine (Cl) 35.5 Bromine (Br) 80 Iodine (I) 127 Traid3: Element Atomic mass Calcium (Ca) 40 Strontium (Sr) 88 Barium (Ba) 137 Dobereiner’s law of triads states that, the atomic mass of the middle element of a triad is the arithmetic mean of the atomic masses of the other two elements.   Example: In the triad of lithium, sodium and potassium. The atomic mass of lithium is 7 and  the atomic mass of potassium is 39. The average of masses of lithium and potassium gives atomic mass of sodium 23.  Drawbacks: All the known elements could not be arranged in the form of triads. This law did not hold good for elements with very low or very high atomic mass.  Example: The arithmetic mean of the atomic masses of fluorine 19 and bromine 80, which comes to 49.5, varies significantly from the atomic mass of chlorine, which is 35.5.  Since Dobereiner’s law could not successfully group elements, the attempts at classification continued. The next attempt came in 1864, when an English chemist, John Newlands, stated his observations in the form of Newlands Law of Octaves. Newlands Law of Octaves: When Newlands arranged elements in according to their atomic weights then there was similarity of every eighth element. Newland described it as "law of octaves". According to this law every eighth element is similar to that of the first element, similar to the first and the eighth notes in the musical scale.  Newlands classification of elements: Li Be B C N O F Na Mg Al Si P S Cl K Ca Example: When starting from lithium, the eighth element is sodium. Similarly, the eighth element from sodium is potassium. Lithium, sodium and potassium show similar properties. Drawbacks: Not valid for elements having atomic masses higher than calcium. Newly discovered elements could not find a place in Newlands table. Mendeleev's periodic table: Mendeleev based his work on the research by Newlands and took it further. He felt that effective grouping of elements and prediction of properties could be based on two parameters: Atomic mass  Chemical reactivity Mendeleev’s periodic law states that "the physical and chemical properties of all elements are the periodic function of their atomic masses".   Row  Group I  Group II  Group III  Group IV  Group V  Group VI  Group VII  Group VIII  1  2  3 H = 1 Li = 7 Na = 23 Be = 9 Mg = 24 B = 11 Al = 27 C = 12 Si = 28 N = 14 P = 31 O = 16 S = 32 F = 19 Cl = 35.5  4  5 K = 39 Cu = 63 Ca = 40 Zn = 65 Ti = 48 V = 51 As = 75 Cr = 52 Se = 79 Mn = 35 Br = 80 Fe = 56 Co = 58.94 Ni = 58.68  6  7 Rb = 85 Ag = 108 Sr = 87 Cd = 112 Y = 89 In = 113 Zr = 90 Sn = 118 Nb = 94 Sb = 120 Mo = 96 Te = 128 I = 127 Ru = 103 Rh = 104 Pd = 106  8  9 Cs = 133 Ba = 137 La = 138 Ce = 140  10  11 Au = 198 Hg = 200 Yb = 173 Tl = 204 Pb = 206 Ta = 182 Bi = 208 W = 184 Os = 191 Ir =193 Pt = 196  12  Th = 232  U = 240 The main features of Mendeleev’s periodic table: The known 63 elements were classified into groups and periods. The table had 8 vertical columns called groups and 12 horizontal rows called periods. In every group, a gradation of physical and chemical properties of elements was observed. The table provided gaps for undiscovered elements. The table helped to predict the properties of three unknown elements of that time. These elements were named eka-boron, eka-aluminium and eka-silicon. When these elements were discovered, they were named scandium, gallium and germanium. The properties of these elements were very close to those predicted by Mendeleev. Merits: The table helped in the correction of atomic mass for many elements. It predicted the existence of some elements that have not been discovered at the time the table was created. Demerits: The atomic weights of two pairs of elements were reversed.  Alkali metals and coinage metals were placed in the same group.  Lanthanides and actinides were not given proper place in the periodic table.  Isotopes were not placed in the periodic table.  The position of hydrogen was not clearly discussed

#### Activities

Activity1: Repo.unnes.ac has developed an interactive video regarding history behind the classification of elements. Explained merits and demerits for each of the classification of elements starting from Dobereiner, Newlands, Lothar Meyer and Mendeleev.Followed by quiz for each of the classiffication. Go to Activity

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Learn Videos. This will help you in easily understanding the future problems which will be complex at times. Concepts NCERT Questions; Extra Questions; About the Author . Question 9: What is pressure? From the Figure We can see that the Maximum Pressure that A-105 flange with 150 pressure class can withstand at 300 Deg C Temperature is 10.2 bar which is lower than our design pressure (50 bar). Topics covered are force and types of force, fluids and fluids pressure. Here the maximum pressure capability is 39.8 bar which is also less than 50 bar. Question 1. Welcome to teachoo टीचू Best Place to Learn Science and Maths Learn now. Finding height of fluid in a barometer. 5 min. BOOK FREE CLASS; COMPETITIVE EXAMS . - Definition, Formula, Unit, Examples, Videos Pressure Formula: Definition, Meaning, Pressure Equation. Atmospheric Pressure Definition Measurement and Instruments. Class 8 Physics Force and Pressure: Force :A push or a pull: A push or a pull on an object is called a Force. The lesson covers all important questions based on force and pressure. Pressure Formula is used to compute force, density, area, pressure, height and gravity. Pressure and Pascal's principle (part 2) Pressure at a depth in a fluid. Overview. The heel is round with a diameter of 1.5 cm. Q1. 3. Download books and chapters from book store. Force: (i) Force is a push or a pull. Previously, you have learned the different kinds of forces simply. What is pressure? We can show that there is atmospheric pressure by carrying out an experiment. Question 2. 2. CBSE Class 8 Science Notes Chapter 11 Force and Pressure Force and Pressure Class 8 Notes Understanding the Lesson. Give two examples each of situations in which you push or pull to change the state of motion of objects. (iii) To apply a force over an object interaction between object and source of force is necessary. Pressure = Force /Area Pressure is inversely proportional to the area on which it is applied. Force acting on per unit area is called (a) non-contact forces (b) contact forces (c) force (d) pressure (d) pressure. 4. BNAT; Classes. BOOK FREE CLASS; COMPETITIVE EXAMS . Next we will move to next higher class i. e, pressure class 300. Question 8: What is gravitational force? force and pressure Book Chosen. Force and pressure of Class 8 Newton, Sir Isaac (1642-1727), English natural philosopher, generally regarded as the most original and influential theorist in the history of science. 3. The Pressure Rating for flanges will be given in Classes. A push or pull on an object is called force. Can you Fill Water in Inverted Glass? Pressure. For example, the air in the tires of vehicles and bicycles exerts pressure which enables them to run nicely. Answer: The force acting on a unit area on an object is called pressure. This time, you will learn how force is defined and classified into different types. Next lesson. Reaching the Age of Adolescence. At Teachoo, you can first read about the concept and then solve the questions related to it. Force and Pressure… Force and Pressure Class 8 Science Chapter 11: In today's Class 8 Science Sprint session in Chapter 11, we discuss Force and Pressure Class 8. 1. Physics Force & Pressure Part 1 (Introduction) Class 8 VIII We move a wooden box by pushing. Class 8. Atmospheric pressure changes with change in altitude. Conservation of Plants and Animals. Force and Pressure Class 8 Science Chapter 11 as per NCERT Book used in CBSE and other Schools. MCQ Questions for Class 8 Science: Ch 11 Force and Pressure. Welcome to teachoo टीचू Best Place to Learn Science and Maths Learn now. We also provide extra questions for revision and practice.In this chapter, we will learnWhat isForceForce Pull refers to that force which tends to 'move the object towards' the direction of the force applied. Calculate the pressure applied by the heel on the horizontal floor? Davneet Singh is a graduate from Indian Institute of Technology, Kanpur. (iv) Whenever force act two object are involved. Pressure increases with depth. NCERT Books. Force and Pressure Class 8 Extra Questions Higher Order Thinking Skills. 2. He has been teaching from the past 9 years. All points at the same level in a liquid are at the same pressure. CBSE Gujarat Board Haryana Board. Answer the following questions in short: 1. Pressure numbers (PN) compared to flange class designations. In addition, it also teaches how a force is able to change the state of motion. Give two examples each of the situations in which you push or pull to change the state of motion of objects. Materials : Metals and Non-Metals. Learn … Pressure caused by air in the atmosphere is called atmospheric pressure. In addition to his invention of the infinitesimal calculus and a new theory of light and color, Newton transformed the structure of physical science with his three laws of motion and the law of universal gravitation. Push refers to the force which tends to 'move the object away' from the direction of the force applied. Cell - Structure and Functions. Question 1. Pressure: The force acting on per unit area, applied to an object in the direction perpendicular to the surface is called pressure. So not suitable. … Our mission is to provide a free, world-class education to anyone, anywhere. Experimental demonstration of atmospheric pressure. Chapter 11 Class 8 - Force And Pressure. Finding height of fluid in a barometer. This is the currently selected item. For example: 150 Lb, 150 Lbs, 150# or Class 150, all are means the same. Different names are used to indicate a Pressure Class. He provides courses for Maths and Science at Teachoo. Davneet Singh. One which applied force, the other which receive force. Total 10 Questions are in this NCERT Exercise, all are solved here. 2. 4 min. He has been teaching from the past 9 years. The chapter also elucidates how force can change the shape of an object. Chapter Chosen. Class 1 - 3; Class 4 - 5; Class 6 - 10; Class 11 - 12; CBSE. The lesson covers the complete explanation of class 8 Chapter 11 Force and Pressure. The chapter will introduce you to the concepts of force. Microorganisms : Friend and Foe . Coal and Petroleum. Quick summary with Stories. Class VIII - Science Chapter 11 - Force and Pressure Other Chapters Crop Production and Management. Synthetic Fibres and Plastics. Forces applied on an object in the same direction add to one another. Buoyant Force and Archimedes' Principle. Force and Pressure - Class 8 : Notes. * "Pression Nominal" is the French equivalent of Pressure Nominal "Pression Nominal" is the rating designator followed by a designation number indicating the approximate pressure rating in bars.. 1 bar = 1x10 5 Pa (N/m 2) = 0.1 N/mm 2 = 10,197 kp/m 2 = 10.20 m H 2 O = 0.98692 atm = 14.5038 psi (lb f /in 2) He provides courses for Maths and Science at Teachoo. Register & get 12 video lessons of Force and Pressure for class 8. Pressure in liquid does not depends on shape, size and surface area of the container. This is because the air pressure … 3. The unit of pressure is Pascal (Pa). Chapter 11 Class 8 - Force And Pressure. 1 min. Class 8 Physics contains chapters that will let students gain knowledge about the concepts of physics and important terms. Class 1 - 3; Class 4 - 5; Class 6 - 10; Class 11 - 12; CBSE. Class, followed by a dimensionless number, is the designation for pressure-temperature ratings as follows: Class 150 300 400 600 900 1500 2500. The strength of a force is usually expressed by its (a) Altitude (b) Duration (c) Direction (d) Magnitude (d) Magnitude. Davneet Singh. CBSE Class 8 Science - Force and Pressure - NCERT Book Chapter 11 - View or Download in PDF format from here for free. Study Materials What is Pressure? Sort by: Top Voted. Exercises. Combustion and Flame. To know more on other related concepts visit BYJU'S. Reproduction in Animals. November 11, 2020 November 10, 2020 by worksheetsbuddy_do87uk. Concepts NCERT Questions; Extra Questions; About the Author . Currently only available for. Grade 8 Force and Pressure Worksheets. NCERT Books. Give two examples of situations in which applied force causes a change in the shape of an object. Atmospheric pressure decreases as we go up from the surface of the earth. science Book Store. Get NCERT Solutions, Notes and Worksheets of Chapter 11 Class 8 - Force and Pressure free at Teachoo. The chapter further moves on to explore forces and the different types. NCERT Books for Class 5; NCERT Books Class 6; NCERT Books for Class 7; NCERT Books for Class 8; NCERT Books for Class … The chapter of Force and Pressure will make these concepts very easy to understand. Access free … Osmotic pressure is the pressure that must be applied to a solution to halt the flow of solvent molecules through a semipermeable membrane (osmosis). (ii) Living and non- living things can apply force. Answer: Gravitational force is the force which is exerted by every object in the universe. Understand the concept of pressure, its definition, the ratio of force by surface area with the help of examples. Davneet Singh is a graduate from Indian Institute of Technology, Kanpur. Pressure does not depend on the surface of the immersed object. Science Class 8 – Chapter 11- Force and Pressure – NCERT exercise solution (Question-Answer) is provided below. Problem 1: A girl weighing 60 Kg wearing high heel shoes stabilises herself on a single heel. If a force F is applied on a surface of area A, then the pressure P is defined as: P = $$\frac {F}{A}$$ As you blow up a balloon, it becomes harder to blow the balloon as it becomes bigger and bigger. Instrument to measure pressure is called as a manometer: Force is a vector quantity which means it also has direction: The pressure is a scalar quantity which means it does not have direction: Force can be acted upon on the face, edges, side or vertices of the object: Pressure … Pressure Exerted by LiquidsWe know that all liquids have weightExample-Water has weightWhen this liquid gets filled inside a container,it exerts pressure because of weight of liquidExample 1 Attaching Balloon to Test TubeSuppose we attach balloon with test tubeWe will fill the test tube with some wa Class 8 Science Chapter 11 Force and Pressure MCQ (Multiple Choice Questions) with Answers is available here in PDF format. CBSE Class 8 Science Force and Pressure Objective Questions help the students to understand the concepts thoroughly and to score good marks. 1. Force and pressure class 8 notes pdf is available here. Give two examples each of the situations in which you push or pull to change the state of motion of objects. (ii) Pull: We draw water from a well by pulling the rope. Force and Pressure Class 8 Science NCERT Textbook Questions. Find detailed video answer solutions to CONCISE Physics Middle School - 8 Force and Pressure Numericals questions taught by expert teachers. A horse pulls a cart. BNAT; Classes. NCERT Solutions For Class 8 Science Chapter 11: In this article, we will provide you with NCERT solutions for Science Class 8th Chapter 11 – Force and Pressure.These NCERT Solutions have been provided by the top teachers and experts at Embibe to help you with your preparation. The introductory section will also describe how this physical quantity is measured and the unit is determined. If two forces act in the opposite directions on an object, the net force acting on it is the difference between the two forces. Force and Pressure: Class 8 Science Chapter 11 Revision Notes Summary. science Subject Chosen. VIEW MORE. We hope the given CBSE Class 8 Science Notes Chapter 11 Force and Pressure Pdf free download will help you. NCERT Books for Class 5; NCERT Books Class 6; NCERT Books for Class 7; NCERT Books for Class 8… That is, when the area is increased the pressure exerted by applying a force is less. A. An archer stretches her … Pressure is defined as the force per unit area. Answer: (i) Push: We close drawer by pushing. It gives real-life examples to help students understand better the concept of it. Know more about force, types of forces & pressure. Solved Examples. Question 10: What is atmospheric pressure? The students to understand the concept of it Pressure Objective Questions help the students to understand the what is pressure class 8 of.... Higher Class i. e, Pressure, its Definition, Formula, unit,,... 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# Define status codes and reporting method for failure modes in faro

XMLWordPrintable

#### Details

• Type: Story
• Status: To Do
• Resolution: Unresolved
• Fix Version/s: None
• Component/s:
• Labels:
None
• Team:
DM Science
• Urgent?:
No

#### Description

Currently faro sets metric values to NaN when the metric cannot be calculated. This does not conform to JSON standards when reporting to SQuaSH, but also it doesn't give us any information about why the calculation failed (or was not done at all). Think about a reporting mechanism for failure modes in faro.

One idea we considered is having status codes that are persisted as extras in lsst.verify.Measurement.

#### Activity

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Some (very rough) initial thought are in this Google doc

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Welcome to mathimatikoi.org;a forum of university mathematics. Enjoy your stay here.

## coordinates of the vertices's of a triangle

Analytic Geometry
jacks
Articles: 0
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If $(4,7)\;\;,(2,0)\;\;,(1,3)$ are the coordinates of foots of perpendicular drawn from a vertices's to the opposite sides


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Humans have long been fascinated by animals that detect the world through sensory systems that we lack, such as dolphins and porpoises, which navigate by echolocation. However, many of these animals, which dwell in coastal waters, are at increasing risk from human activity. Ursula Verfuß from the University of Tübingen explains that many die entangled in fishermen's nets; either they don't perceive the nets or they don't perceive them as a threat,' she says. Knowing that harbour porpoises residing in the German Baltic are particularly at risk, Verfuß and her colleagues Lee Miller, Peter Pilz and Hans-Ulrich Schnitzler were curious to know how the animals perceive the world around them. Having already discovered that the porpoises navigate by reducing the interval between echolocating clicks as they approach a landmark, the team decided to find out how the animals adjust their sonar as they close in on a tasty snack(p. 823).

Verfuß travelled to the Fjord&Bælt centre in Kertminde,Denmark, to work with two young porpoises, Freja and Eigil. According to Verfuß, the porpoises were very cooperative and fun to work with, but working in the open was a challenge. We couldn't film for days after a storm because the water was disturbed and another time the enclosure was full of jelly fish,' Verfuß recalls. However, when conditions were good, one of the porpoises' trainers threw a brook trout into the porpoises' enclosure while Verfuß filmed the animals and recorded their echolocation clicks as they homed in on the victim.

According to Verfuß, the porpoises speeded up after hearing the splash and eventually rolled onto their backs in the final moments before sucking the fish down. And when Verfuß repeated the experiments with Freja's eyes covered, she slowed a little but still caught the fish. The porpoises could hunt successfully by echolocation alone, but how were they using echolocation to locate the hapless fish?

Analysing the porpoises' click sequences, the team realised that the pursuit could be broken down into three phases: search, initial approach and final approach. During the search phase, the porpoises seemed to lock their navigation system onto a local landmark and gradually reduced the time intervals between clicks as they closed in. But as soon as the animals spotted the trout, the click pattern changed. The porpoises maintained a constant average click interval as they drew closer to the victim until they were close enough to pounce. Then they rapidly accelerated their click rate and reduced the click interval to a few milliseconds, just like echolocating bats, which produce a buzz of clicks in the moments before capturing an insect.

Verfuß admits that she hadn't expected the porpoises to switch to an almost constant click interval during the initial approach phase. She had thought that the animals would continue shortening the click interval, sending clicks out as soon as the echo returned, speeding up the echolocation process as they approached the trout. However, Pilz suggested that maybe the porpoises switch to a constant click interval to confuse their targets. Verfußexplains that some fish have good hearing, and could be alerted to the porpoises' approach by the accelerating clicks. According to Verfuß, it is possible that by switching to a constant average click rate, the porpoises lull their prey into a false sense of security, making it easier to sneak up and gulp them down.

Verfuß, U. K., Miller, L. A., Pilz, P. K. D. and Schnitzler, H.-U. (
2009
). Echolocation by two foraging harbour porpoises (Phocoena phocoena).
J. Exp. Biol.
212
,
823
-834.


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# 3/4-Lie superalgebras: how much of a theory can one develop?

Let $\mathfrak{s} = \mathfrak{s}_0 \oplus \mathfrak{s}_1$ be a real Lie superalgebra. (The ground field does not matter much, but at least one formula will not work as written if the characteristic is 2 or 3.) Recall that this means that there is a bilinear 2-graded bracket $[-,-]$ with three components

(a) $\mathfrak{s}_0 \times \mathfrak{s}_0 \to \mathfrak{s}_0$ (skewsymmetric)

(b) $\mathfrak{s}_0 \times \mathfrak{s}_1 \to \mathfrak{s}_1$

(c) $\mathfrak{s}_1 \times \mathfrak{s}_1 \to \mathfrak{s}_0$ (symmetric)

satisfying the Jacobi identity, which splits into 4 components, which can be paraphrased as

(1) $\mathfrak{s}_0$ is a Lie algebra under (a)

(2) $\mathfrak{s}_1$ is an $\mathfrak{s}_0$-module under (b)

(3) the map in (c) is $\mathfrak{s}_0$-equivariant

(4) $[[x,x],x] = 0$ for all $x \in \mathfrak{s}_1$

The fact that the first three components can be written using words, whereas the fourth is easiest via a formula, suggests that they should perhaps be treated differently.

Indeed, over time I have come across many examples of superalgebras where the first three components of the Jacobi identity are satisfied but not the fourth. I'd like to call them 3/4-Lie superalgebras. I would like to know how far can this notion be pushed and in particular how much of the theory of Lie superalgebras still works in the 3/4 case.

To motivate this seemingly random question, let me end by pointing out one generic example where they arise. There are others, but they are lengthier to describe.

Let $\mathfrak{g}$ be a metric Lie algebra; that is, a Lie algebra with an ad-invariant inner product $(-,-)$ and let $V$ be a symplectic $\mathfrak{g}$-module; that is, one possessing a $\mathfrak{g}$-invariant symplectic form $\langle-,-\rangle$. Now let $\mathfrak{s} = \mathfrak{g} \oplus V$. Then maps (a) and (b) are obvious: given by the Lie bracket on $\mathfrak{g}$ and the action of $\mathfrak{g}$ on $V$, respectively. Map (c) is the transpose of map (b) using the inner products of both $\mathfrak{g}$ and $V$; in other words, if $x,y \in V$ then $[x,y] \in \mathfrak{g}$ is defined by $$([x,y],a) = \langle a\cdot x,y\rangle$$ for all $a \in \mathfrak{g}$.

Then it is easy to see that $[x,y] = [y,x]$ and that (1)-(3) are satisfied, whereas in general (4) is not satisfied and instead defines a subclass of symplectic $\mathfrak{g}$-modules.

-

Suppose that the even part $s_0$ is a semisimple Lie algebra $g$. Then $s_1$ is can be a self-dual representation $V$ of $g$. Unless possibly $g$ is $E_6$, I don't think that $V$ can be anything other than a self-dual representation. So then the form is a symmetric element of $\mathrm{Inv}(g \otimes V \otimes V)$, which is a vector space whose dimension can be computed. The dimension is at most the rank of $g$ when $V$ is irreducible. Indeed it is usually the rank of $g$, when the highest weight of $V$ is far away from the walls of the Weyl chamber. The dimension of the symmetric part is smaller, but it is often non-zero. (This is the part that I don't know how to compute off the top of my head.)
So inevitably there will be a classification of these 3/4 Lie algebras using these branching rules. Besides the classification, the only theory that springs to mind is representations of these 3/4 Lie algebras. A representation $W$ would first off be a representation of $g$ (and I suppose a super vector space?). Then there would be a $g$-invariant map $V \otimes W \to W$ which represents the action of $V$. I don't see a rationale for imposing restrictions on this map other than $g$-invariance, for otherwise $g \oplus V$ would not be the adjoint representation of itself. So once again, there is some Cartan-Weyl classification that says what $W$ can be, and I'm not sure what more you could say.


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# Derivative with respect to something else

#### __redzone

I have a problem that I'm stuck on. In my calculus class we've only learned to take the derivative with respect to x, y, or time. The question is;

y = x^2 + x. The derivate of y with respect to 1/(1-x) is .. ? If someone could help me get started, specifically how to get started it'd be appreciated. Thanks.

#### Fredrik

Staff Emeritus
Gold Member
This is how a physicist would do it:

$$\frac{d}{d(\frac{1}{1-x})}=\frac{dx}{d(\frac{1}{1-x})}\frac{d}{dx}=\frac{1}{\frac{d(\frac{1}{1-x})}{dx}}\frac{d}{dx}=\frac{1}{\frac{1}{(1-x)^2}}\frac{d}{dx}=(1-x)^2\frac{d}{dx}$$

The interpretation of this is that to take the derivative with respect to 1/(1-x) is the same as taking the derivative with respect to x and then multiplying the result with (1-x)^2.

This is another way to do it:

$$f(x)=x^2+x$$

Let g be the function that satisfies

$$f(x)=g\big(\frac{1}{1-x}\big)=g(h(x))$$

The definition of h(x) is of course just h(x)=1/(1-x).

What we're looking for is

$$g'(h(x))$$.

Note that $$f=g\circ h$$.

$$f'(x)=(g\circ h)'(x)=g'(h(x))h'(x)$$

$$g'(h(x))=\frac{f'(x)}{h'(x)}=(1-x)^2 f'(x)$$

The second approach has the advantage that it's much easier to explain every step.

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#### Fredrik

Staff Emeritus
Gold Member
I decided to give some thought to what I was actually doing when I did the first calculation, and I came to the conclusion that this is what the first calculation actually says:

$$g'(h(x))=(f\circ h^{-1})'(h(x))$$

$$=f'(h^{-1}(h(x)))h^{-1}'(h(x))=h^{-1}'(h(x))f'(x)$$

$$=\frac{1}{h'(h^{-1}(h(x)))}f'(x)=\frac{1}{h'(x)}f'(x)$$

$$=\frac{1}{\frac{1}{(1-x)^2}}f'(x)$$

$$=(1-x)^2 f'(x)$$

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#### Gib Z

Homework Helper
Im not the best at this, but i would let what you want with respect to, equal u, and then find what y equals in terms of u.

#### Jheriko

Im not the best at this, but i would let what you want with respect to, equal u, and then find what y equals in terms of u.

This is what I would do to, and just to clarify, this is usually referred to as "making a subsitution". Making the substitiution $u = \frac{1}{1-x}$ and then finding $\frac{dy}{du}$ will solve the problem. It also makes it quite a lot easier to write y in terms of u since we can rearrange the expression defining u:

$$\frac{1}{1-x} = u$$
$${1-x} = \frac{1}{u}$$
$${-1+x} = \frac{-1}{u}$$
$$x = \frac{-1}{u} + 1$$ or,
$$x = 1 - \frac{1}{u}$$

Which can then be substituted back into the original

$$y = x^2 + x$$
$$y = \left(1 - \frac{1}{u}\right)^2 + \left(1 - \frac{1}{u}\right)$$
$$y = 2 - \frac{3}{u} + \frac{1}{u^2}$$

Which, barring any mathematical errors on my part, should allow you to find the derivative $\frac{dy}{du}$ as required. Once found just substitute back the original expression we had for u: $u = \frac{1}{1-x}$

This is of course identical to using h(x) in place of u and g(x) from the above posts would be the new function for y in terms of u which is given above. The only reason I chose to use the u is that it is tidier to write and makes it "more obvious" what you should do at each stage, since it takes the form of a variable, rather than the less familiar form of a function. Personally I get confused when I see something like $f'(g(x))$ : is it the derivative of f with respect to x, or with respect to g(x)?

#### Fredrik

Staff Emeritus
Gold Member
Personally I get confused when I see something like $f'(g(x))$ : is it the derivative of f with respect to x, or with respect to g(x)?
It doesn't really make sense to say that the derivative of a function $f:\mathbb{R}\rightarrow\mathbb{R}$ is with respect to a variable with a specified name. There's only one variable, and it doesn't matter if we call it x, y, t or even g(x).

It only makes sense to specify what the derivative is with respect to when we haven't already specified what function we're taking the derivative of. For example, it wouldn't make sense to talk about "the derivative of f(g(x))", because f(g(x)) isn't a function, it's a number. But if we say that the derivative is with respect to x, we make it clear that the function we're taking the derivative of is the map $x\mapsto f(g(x))$ (also known as $f\circ g$). If we say that the derivative is with respect to g(x), we're specifying that the function we're taking the derivative of is the map $y\mapsto f(y)$ (also known as f).

f'(g(x)) is the derivative of f, evaluated at g(x). Another way of saying that is that f'(g(x)) is the derivative of f(g(x)) with respect to g(x), evaluated at g(x).

But I guess I'm nitpicking here. Your post is very good. A lot of people probably think your explanation is much easier to understand than mine, and my advice to the thread starter is to try to understand both methods.

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