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Plasma synthetic jet (some called "spark jet" or "pulsed-plasma jet"）is a new type of plasma aerodynamic actuation. It is a synthetic jet that is generated by striking an electrical discharge in a small cavity and the gas in the cavity spurts out through a small orifice in a high speed after pressurization owing to the heating caused by electrical discharge. To study the performance characteristics of two-electrode plasma synthetic jet and the influence of different actuator orifice shapes，a phenomenological simulation of two-electrode plasma synthetic jet built by a single energy deposition was accomplished by equating the physical effects of the spark discharge with gas Joule heating and adding source term in energy equation. The kinetic energy and heat injection into outer flow field of plasma synthetic jet were used as characterizations of " impact effect，，and "thermal effect''. The results show that the kinetic energy and heat injection of plasma synthetic jet are mostly concentrating in primary jet during the self-sustained oscillation process established by a single discharge, and "thermal effect" of jet works longer than "impact effect，，. Overall energy efficiency of two-electrode plasma synthetic jet actuator is about 2. 3% at 1 atm. The influence of different actuator orifice shapes was studied and it shows that shrinking orifice can effectively improve the jet velocity, but will reduce jet momentum and saturation frequency simultaniously. [ABSTRACT FROM AUTHOR]

Massive multiple-input multiple-output ( Massive MIMO) systems precoding techniques are based on users to configure a single antenna. Witli the development of wireless communication technology and audio and video and picture taking to enhance demand, now, there are more and more intelligent terminals with multiple antennas. It means that the number of user terminals antenna is gradually increased. To solve this problem, we adopt the block diagonalization (BD) precoding algorithm and do experimental study. We analyze the relationships between energy efficiency and spectral efficiency of the downlink large-scale antenna system, the number of base stations transmitting antenna and the cell radius, then we obtain the closed relationship between the energy efficiency and spectral efficiency, and the optimal energy efficiency. Theoretical analysis and simulation results show that reasonably setting the operating point of spectral efficiency, increasing the number of base stations transmitting antenna, as well as reducing the cell radius can enhance the system s energy efficiency, it also confirm that the microcell deployed has great benefit to improve energy efficiency of the system. [ABSTRACT FROM AUTHOR]

This paper studied the energy consumption of CSMA/CA under self-organized circumstances, and compared with that of traditional CSMA protocols. It described the problem of hidden and exposed terminals, and the improvement of CSMA/CA protocol compared to traditional CSMA protocols. Simulation results show that compared with non-persistent CSMA protocol, the CSMA/CA protocol with lower sensitivity to network load, can get higher energy efficiency, and have higher energy efficiency even when the network load is higher. [ABSTRACT FROM AUTHOR]

This paper proposed an energy-eeficient and/or user fairnees localization technology by analyzing real GPS trace of people in campuses and what was the best method for selfish mobile users to collaborate for energy-efficient localization. At the same time, it developed an optimal centralized algorithm which minimized a time average GPS power of mobile devices satisfying fixed accuracy bound and guaranteed fairness among devices by adopting the idea of coHaboration among proxy devices. Further, it also developed a distributed near-optimal algorithm by controHing the backoff time and GPS-off duration. Finally, through the extensive simulations under several topologies, it verified the high energy-eeficiency and fairnees among devices of this algorithms. [ABSTRACT FROM AUTHOR]

High energy efficiency with high performance, low energy consumption, and QoS support is one of the research challenges in cloud computing. According to this issue, the current studies trade off the three aspects o£ the issue by fixing one factor and optimizing the others, which lack an efficient energy efficiency calculation method and evaluation model that integrate the three aspects and describe the "degree" of the energy efficiency better. A QoS parameters reduction approach and a weighted energy efficiency model are proposed, which introduce the system performance as a key indicator into QoS, reduce the discrete QoS parameters into a unified dimension, establish the energy efficiency classification levels of the cloud data centers, describe the energy efficiency as a qualitative concept, and realize the energy efficiencys qualitative evaluation in cloud computing environments. Besides, the energy efficiencies of the cloud data centers in single-machine, homogenous, and heterogeneous cloud computing environments are evaluated, and experimental results show that the proposed energy efficiency model and evaluation method are effective for evaluating the QoS level and energy consumption in cloud computing environments. [ABSTRACT FROM AUTHOR]

In the global energy crisis, many researchers begin to pay close attention to the problem of data centers, energy consumption. On the premise of meeting the users, demand, reducing the active nodes of adata center can effectively reduce the whole energy consumption. Virtual machine migration is a traditional way to reduce active nodes, but causes huge system cost. An energy-saving algorithm for MapReduce-based virtual cluster, named Online Time Balance Algorithm (OTBA), is proposed. The proposed algorithm can reduce the number of active physical nodes, reduce the energy consumption effectively, and avoid migrating the virtual machines. The objective function and the variable factors are determined by building the energy consumption model, the queue model and the MapReduce performance model. Since OTBA is based on virtual cloud environment and online MapReduce, it can make a tradeoff between the runtime of virtual machines and the resource utilization so as to minimize the number of the activated physical servers in the data center and the energy consumption. At last, the algorithm is validated through experiments in simulation environment and on Hadoop platform. [ABSTRACT FROM AUTHOR]

It has been widely accepted in network research community that there is a trade-off between Internet power consumption and performance. Some approaches were proposed to take only one of them as primary while considering the other one as secondary. Hence, it is the problem to be investigated in this paper which is how to take the Internet power consumption as same importance as performance to optimize in a collaborative way. In this paper, we propose a general optimization model to reduce the Internet power consumption while improving the network performance. To make it practical, we materialize it to a linear model by introducing and defining cost functions and power-bandwidth function. The evaluation results show that, the optimal solution of the linear programming model simultaneously reduces the network maximum link utilization and power consumption. Moreover, each of the two indices is respectively and approximately equal to the corresponding one-side optimal solution. Thus, the network power consumption and performance are collaboratively optimized. Comparing to the existing Internet, for maximum link utilization, the highest reduction of the optimal solution of the proposed model is 60.6% and the lowest is 45.8%; for power consumption, the highest reduction of the optimal solution of the model is 83.3% and the lowest is 56.7% [ABSTRACT FROM AUTHOR]

Improving energy efficiency is an important approach to decrease energy consumption, and the magnitude of energy rebound effect caused by technology progress directly affects the effectiveness of energy effect policies. This paper briefly reviews the main theory of energy rebound effect, with China's 30 provincial government panel data from 1996 to 2011, builds a double logarithm and a panel error correction model to empirically analyze the direct rebound effect of urban residential electricity use. The results show that: the Chinese urban residential electricity consumption exists a partial rebound effect, and the longterm rebound effect is 0.71, the short-term rebound effect is 0.47. A majority of the expected reduction in urban residential electricity consumption from efficiency improvement could be offset due to the existence of rebound effect. The rebound effect impairs the functions of energy efficiency policies, and therefore the Chinese government should take the effect into consideration when formulating energy policies. [ABSTRACT FROM AUTHOR]