18404090
Dynamic frequency scaling with buffer insertion for mixed workloads
This paper presents a method to reduce the energy of interactive systems for mixed workloads: multimedia applications that require constant output rates and sporadic jobs that need prompt responses. The authors' method divides multimedia programs into stages and inserts data buffers between them. Data buffering has three purposes: (1) to support constant output rates; (2) to allow frequency scaling for energy reduction; and (3) to shorten the response times of sporadic jobs. The authors construct frequency-assignment graphs. Each vertex represents the current state of the buffers and the frequencies of the processor. The authors develop an efficient graph-walk algorithm that assigns frequencies to reduce energy. The same method. can be applied to perform voltage scaling and the combination of frequency and voltage scaling. The authors' experimental results on a Strong-ARM-based computer show that four discrete frequencies are sufficient to achieve nearly maximum energy saving. The method reduces the power consumption of an MPEG program by 46%. The authors also demonstrate a case that shortens the response time of a sporadic job by 55%.
2733921
Joint power management of memory and disk
The paper presents a scheme to combine memory and power management for achieving better energy reduction. Our method periodically adjusts the size of physical memory and the timeout value to shut down a hard disk for reducing the average power consumption. We use Pareto distributions to model the distributions of idle time. The parameters of the distributions are adjusted at run-time for calculating the corresponding timeout value of the disk power management. The memory size is changed based on the inclusion property to predict the number of disk accesses at different memory sizes. Experimental results show more than 50% energy savings compared to a 2-competitive fixed-timeout method.
9215156
Energy management using buffer memory for streaming data
This work presents a new approach for energy management by inserting data buffers. The buffers are managed using the concept of inventory control by treating energy as cost and computation as production. The data stored in the buffers are considered as merchandise. Our method provides a mathematical framework to develop general strategies managing the energy consumption in computers. The approach can solve a wide range of problems. For example, it can calculate the needed buffer sizes to achieve optimal energy savings. It can derive the conditions when a standby state saves energy. The method also shows the effect of load balancing on energy conservation and can handle the variations of data rates. We use sensor networks as case studies and demonstrate more than 20% energy savings.
161273
Dynamic power management for streaming data
This paper presents a method that uses data buffers to smoothen request variations and to create long idleness for power management. This method considers the power consumed by the buffers and assigns an energy penalty for buffer underflow. Our approach provides analytic formulas for calculating the optimal buffer sizes and the amount of data to store in the buffers. We use video prefetching as a case study and obtain power savings of more than 74% for MPEG-1 and 34% for MPEG-2 videos.
15594355
Replacing Failed Sensor Nodes by Mobile Robots
Sensor replacement is important for sensor networks to provide continuous sensing services. Existing approaches relocate redundant nodes to fill the holes created by failed sensors and require all or most sensor nodes to have mobility. However, mobility equipment is expensive while technology trends are scaling sensors to be smaller and cheaper. In this paper, we propose to use a small number of mobile robots to replace failed sensors in a large-scale static sensor network. We study algorithms for detecting and reporting sensor failures and coordinating the movement of robots that minimize the motion energy of mobile robots and the messaging overhead incurred to the sensor network. A manager receives failure reports and determines which robot to handle a failure. We study three algorithms: a centralized manager algorithm, a fixed distributed manager algorithm, and a dynamic distributed manager algorithm. Our simulations show that: (a) The centralized and the dynamic distributed algorithms have lower motion overhead than the fixed distributed algorithm. (b) The centralized algorithm is less scalable than the two distributed manager algorithms. (c) The two distributed algorithms have higher messaging cost than the centralized algorithm. Hence, the optimal choice of the coordination algorithm depends on the specific scenarios and objectives being optimized.
14287933
Statistically optimal dynamic power management for streaming data
This paper presents a method that uses data buffers to create long periods of idleness to exploit power management. This method considers the power consumed by the buffers and assigns an energy penalty for buffer underflow. Our approach provides analytic formulas for calculating the optimal buffer sizes without subjective or heuristic decisions. We simulate four different hardware configurations with MPEG-1, MPEG-2, and MPEG-4 formats as a case study. Our results indicate that the optimal buffer size varies significantly for different data formats on different hardware. Simulation results indicate that 16 MB buffers are sufficient for MPEG-1, MPEG-2, and MPEG-4 video streams from a microdrive or a network card, but transfers from an IDE disk require buffer sizes ranging from 16 MB to 176 MB, depending on each video's statistical properties.
5344006
Min/max on-chip inductance models and delay metrics
This paper proposes an analytical inductance extraction model for characterizing min/max values of typical on-chip global intercon-nect structures, and a corresponding delay metric that can be used to provide RLC delay prediction from physical geometries. The model extraction and analysis is efficient enough to be used within optimization and physical design exploration loops. The analytical min/max inductance approximations also provide insight into the effects caused by inductances.
14054770
A new approach for ground moving target indication in foliage environment
Ground moving target indication (GMTI) in foliage environment is a challenging problem, because the strong echoes from dense foliage environment and big attenuation of the radar microwave often make it difficult for traditional time frequency distributions to clearly and locally represent the Doppler frequency. This paper introduced a new approach to improve the performance of GMTI. This so-called Hilbert Huang Transform (HHT) method composes of empirical mode decomposition (EMD) and Hilbert transform technique. EMD is applied to extract target signal from interference and the associated Hilbert transform calculates the instantaneous Doppler frequency, representing a novel Hilbert spectrum in time frequency domain. Both simulative and experimental signals are used to validate the efficiency of HHT. This adaptive approach offers higher signal to disturbance ratio and higher resolution in the time frequency distribution.
27140699
Differential Algebraic Method for Aberration Analysis of Electron Optical Systems
Differential algebraic method is a powerful technique in computer numerical analysis. It presents a straightforward method for computing arbitrary order derivatives of functions with extreme high accuracy limited only by the machine error. When applied to nonlinear dynamics systems, the arbitrary high order transfer properties of the system can be derived directly. In this paper, the principle of differential algebraic method is applied to calculate high order aberrations of electron optical systems. As an example, an electrostatic lens with an analytical expression has been calculated using this method. Relative errors of the Gaussian properties and spherical aberration coefficient of the lens compared with the analytic solutions are of the order 10− 11 or smaller. It is proved that differential algebraic aberration method is very helpful with high accuracy for high order aberration analysis and computation of electron optical systems.
3148116
Modeling of wave behavior of substrate noise coupling for mixed-signal IC design
A new full-wave method is introduced for substrate noise analysis and simulation. The method is based on solution of the wave equation for the magnetic potential and can be implemented using standard circuit simulators. We compare the new method with the standard quasi-static method for typical substrate profiles and investigate the limits of validity of the quasi-static method.
8110517
FGKA: a Fast Genetic K-means Clustering Algorithm
In this paper, we propose a new clustering algorithm called Fast Genetic K-means Algorithm (FGKA). FGKA is inspired by the Genetic K-means Algorithm (GKA) proposed by Krishna and Murty in 1999 but features several improvements over GKA. Our experiments indicate that, while K-means algorithm might converge to a local optimum, both FGKA and GKA always converge to the global optimum eventually but FGKA runs much faster than GKA.