Average Energy Of System Research Articles

Energy efficient multi-user task offloading through active RIS with hybrid TDMA-NOMA transmission

In this paper, we address the challenge of minimizing system energy consumption for task offloading within non-line-of-sight (NLoS) mobile edge computing (MEC) environments. Our approach integrates an active reconfigurable intelligent surface (RIS) and employs a hybrid transmission scheme combining time division multiple access (TDMA) and non-orthogonal multiple access (NOMA) to enhance the quality of service (QoS) for user task offloading. The formulation of this problem as a non-convex optimization issue presents significant challenges due to its inherent complexity. To overcome this, we introduce an innovative method termed element refinement-based differential evolution (ERBDE). Initially, through rigorous theoretical analysis, we optimally determine the allocation of local computation resources, computation resources at the base station (BS), and transmit power of users, while maintaining fixed values for the offloading ratio, amplification factor, phase of the reflecting element, and the transmission period. Subsequently, we employ the differential evolution (DE) algorithm to iteratively fine-tune the offloading ratio, amplification factor, phase of the reflecting element, and transmission period towards near-optimal configurations. Our simulation results demonstrate that the implementation of active RIS-supported task offloading utilizing the hybrid TDMA-NOMA scheme results in an average system energy consumption reduction of 80.3%.

Energy-saving diagnosis of public buildings based on multi-objective optimization algorithm

ABSTRACT This study focuses on existing ventilation, heating, and air conditioning systems in public buildings and mainly considers three objectives: system energy consumption, indoor thermal comfort, and efficiency. A multi-objective diagnosis system is established, which correlates evaluation indicators with key equipment, forming a clear hierarchical diagnosis system. Meanwhile, particle swarm optimization algorithm is combined with linear weighting method to optimize the operating parameters of key equipment based on the diagnosis results, obtaining the optimal parameters of various operating scenes. For winter conditions, the average system energy consumption is 34.2 W/m2, the average system energy efficiency ratio is 1.5, and the average indicator for indoor thermal environment is 1.06. For summer conditions, the average energy consumption of the systems is 28.9 W/m2, the average energy efficiency ratio is 2.2, and the average indicator for indoor thermal environment is – 0.82. Compared with the measured results, most of the optimized indicators are better, but the system energy efficiency ratio is slightly lower than the measured results for winter conditions. Through the established diagnosis system and optimization method, this research evaluates and optimizes the existing the systems in public buildings. Demonstrating the effectiveness of the established diagnosis system and optimization method.

Role of proton exchange membrane fuel cell in efficiency improvement of ammonia–hydrogen fusion zero-carbon powertrains for long-haul, heavy-duty transportation

Ammonia fuel, a transport zero-carbon energy carrier with a much lower life-cycle greenhouse gas footprint than existing fuels and the ability to overcome the storage and transportation challenges of hydrogen fuel, is an effective means of realizing the energy transition for long-haul, heavy-duty transportation such as heavy trucks. Although the efficient use of liquid ammonia fuel cannot be realized directly at this stage, it can be realized indirectly by converting ammonia fuel into hydrogen and combining the hydrogen generated with ammonia in an ammonia–hydrogen fusion fuel supply method. In this study, we assess four ammonia–hydrogen fusion-fueled zero-carbon powertrains for heavy-duty commercial vehicles, each of which is designed to determine its most efficient green zero-carbon fuel utilization scenario at the point of steady state operation as well as over the entire power-demand interval. It was found that the required engine capacity decreases with the increase of the hydrogen energy ratio in the ammonia–hydrogen composite fuel. Considering the indicated thermal efficiency of the engine and the combustion stability in the cylinder, the ammonia–hydrogen composite fuel with 30% hydrogen energy share was selected for the matching design of the powertrains. The study results show that powertrain equipped with engine and fuel cell are more energy efficient than others. The powertrain with range extender consisting of the engine and fuel cell takes ammonia dissociation separation unit and fuel cell as an important part of engine exhaust gas heat recovery, which reduces the dependence of ammonia cracking hydrogen production on electric heating power. By regulating the energy distribution ratio between the engine and the fuel cell, the system can be maintained at a high level of energy efficiency. Under different power requirements of highway application scenarios, the system efficiency is not less than 36%, and the system energy utilization efficiency is higher than 44%. Compared to engine direct drive powertrain, engine range-extended powertrain, and fuel cell range-extended powertrain, the average system efficiency increases by 30.8%, 8.68%, and 14.24%, while the average system energy utilization increased by 41.12%, 25.26%, and 39.43%, respectively.

Adaptive power allocation with energy efficiency in 5 g multitier networks using a hybrid heuristic approach

Nowadays, the cellular network has become a part of every human being's life. Cellular communication, hand in hand with information technology, has reduced the physical work performed by people. As there is great improvement and development in the fields of electronics and communication, the accumulation of data has also increased at a high rate. One of the cons observed due to the development of huge data is data traffic. The currently used 4G mobile communication technology is facing congestion, reduced capacity, shortages in bandwidth, slower data rate problems, and interference. The technology is equipped to connect with a large number of devices, overcoming the issue of network traffic that arises in 4G communications. Recent growth in technology has given the best solution with 5G communication. This proposed study focuses on the energy-efficient power allocation in a 5G multitier heterogeneous network, which consists of relays, deployment of small cells, and device-to-device communication. Here, a new methodology like Hybrid Heuristic algorithm is proposed for Adaptive Power Allocation with Energy Efficiency in 5G Multitier Networks which is a combination of ACO (Ant Colony Optimization) and PSO (Particle Swarm Optimization) algorithms to produce an efficient power allocation scheme for 5G downlink systems. The novelty of this research work is the integration of two optimization algorithm for adaptive power allocation in 5G network. The average SNIR value of the proposed Heuristic Approach is compared with the existing algorithms like SOA, and NCOL based on D2D user, micro user and pico user. The proposed Heuristic technique average system energy efficiency, and average system spectral efficiency also calculated and compared with the existing techniques such as SOA and NOCL.

STICKER-IM: A 65 nm Computing-in-Memory NN Processor Using Block-Wise Sparsity Optimization and Inter/Intra-Macro Data Reuse

Computing-in-memory (CIM) is a promising architecture for energy-efficient neural network (NN) processors. Several CIM macros have demonstrated high energy efficiency, while CIM-based system-on-a-chip is not well explored. This work presents a CIM NN processor, named STICKER-IM, which is implemented with sophisticated system integration. Three key innovations are proposed. First, a CIM-friendly block-wise sparsity (BWS) architecture is designed, enabling both activation-sparsity-aware acceleration and weight-sparsity-aware power-saving. Second, an adaptive kernel-/channel-order (KCO) mapping and intra-/inter-macro scheduling strategy is proposed to improve macro utilization and data reuse. Third, an efficient BWS-optimized CIM (BWS-CIM) macro with adaptive power-OFF ADCs is implemented. The STICKER-IM chip was fabricated in 65-nm CMOS technology. Experimental results show 5.8–158-TOPS/W average system energy efficiency on the sparse NN models. The macro/system-level energy efficiency is <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$4.23\times / 3.06\times $ </tex-math></inline-formula> higher compared with the state-of-the-art CIM macros and processors.

Wireless Power and Energy Harvesting Control in IoD by Deep Reinforcement Learning

Internet of Drones (IoD), which deploys several drones in the air to collect ground information and send them to the IoD gateway for further processing, can be applied in traffic surveillance and disaster rescue. The performance of IoD is greatly affected by drones' battery capacities. We hence utilize the energy harvesting technology to charge the batteries and the wireless power control to adjust the drone wireless transmission power in order to address this challenge. In our work, we investigate the joint optimization of power control and energy harvesting control to determine each drone's transmission power and the transmitted energy from the charging station in time-varying IoD networks. Our objective is to minimize the long-term average system energy cost constrained by the drones' battery capacities and quality of service (QoS) requirements. A Markov Decision Process (MDP) is formulated to characterize the power and energy harvesting control process in time-varying IoD networks. A modified actor-critic reinforcement learning algorithm is then proposed to tackle our problem and its performance is demonstrated via extensive simulations.

Tuning Resonance Frequency of Spin Wave Localized in an Isolated Skyrmion by Magnetoelectric Couplings

Understanding the dynamic behavior of an isolated skyrmion with external perturbations has been obstructed due to the difficulty in experimentally observing such an instantaneous phenomenon within picoseconds. Herein, we theoretically investigated the spin-transfer-torque-induced dynamics of an isolated skyrmion excited by external nanosecond-pulse perturbations. It is found that a redshift of the resonant frequency appears under a pulse polarized current with [Formula: see text][Formula: see text]A/m2 and [Formula: see text][Formula: see text]GHz, while a blueshift is presented under a combined perturbation of the pulse polarized current and an out-of-plane ac magnetic field. The physic origins of the redshift and the blueshift are ascribed to the increased average energy of system from [Formula: see text][Formula: see text]J to [Formula: see text][Formula: see text]J and integer multiple (twofold and fourfold) oscillation frequencies of total energy, respectively. The present study could thus provide an insight to the micromagnetic dynamics of skyrmion under the magnetoelectric couplings.

Mini EXPLORER II: a prototype high-sensitivity PET/CT scanner for companion animal whole body and human brain scanning

As part of the EXPLORER total-body positron emission tomography (PET) project, we have designed and built a high-resolution, high-sensitivity PET/CT scanner, which is expected to have excellent performance for companion animal whole body and human brain imaging. The PET component has a ring diameter of 52 cm and an axial field of view of 48.3 cm. The detector modules are composed of arrays of lutetium (yttrium) oxyorthosilicate (LYSO) crystals of dimensions 2.76 × 2.76 × 18.1 mm3 coupled to silicon photomultipliers (SiPMs) for read-out. The CT component is a 24 detector row CT scanner with a 50 kW x-ray tube. PET system time-of-flight resolution was measured to be 409 ± 39 ps and average system energy resolution was 11.7% ± 1.5% at 511 keV. The NEMA NU2-2012 system sensitivity was found to be 52–54 kcps MBq−1. Spatial resolution was 2.6 mm at 10 mm from the center of the FOV and 2.0 mm rods were clearly resolved on a mini-Derenzo phantom. Peak noise-equivalent count (NEC) rate, using the NEMA NU 2-2012 phantom, was measured to be 314 kcps at 9.2 kBq cc−1. The CT scanner passed the technical components of the American College of Radiology (ACR) accreditation tests. We have also performed scans of a Hoffman brain phantom and we show images from the first canine patient imaged on this device.

Experimental investigation of solar photovoltaic operated ice thermal storage air-conditioning system

Under the double pressure of energy shortage and environmental pollution, ice thermal storage air-conditioning and photovoltaic air-conditioning has been applied in refrigeration field. In order to improve application scope and reduce investment operation cost, the ice thermal storage adopted to store solar energy in ice thermal storage air-conditioning driven by distributed photovoltaic energy system was proposed in this paper. Two operation models had been tested by experiment. Research results revealed all of the solar energy accepted by PV array had been stored with ice or cold water. Moreover, the experimental results analysis showed that it is feasible to use ice thermal storage instead of battery bank to store solar energy in the field of distributed photovoltaic refrigeration. In operation mode 1, the average system energy utilization efficiency was 0.525 and the average refrigeration efficiencies η¯rand η¯rs were 0.7292 and 0.0690, respectively. When system operated in mode 2, the average system energy utilization efficiency was 0.3377 and the refrigerator performances parameters η¯rand η¯rs were 4.49 and 0.3875, which were 6.16 times and 5.62 times of the average η¯r and η¯rs under working model 1.

Experimental Evaluation of the Ground Source Heat Pump System with a New Control Strategy - A Case Study in Tianjin

In order to improve the cooling performance of the ground source heat pump (GSHP) system, save the operating cost and reduce the heat discharged into the ground soil, a new free cooling control strategy is proposed in this paper, with which the circulating water in the ground heat exchanger is used to cool the building directly. Firstly, an office building located in Tianjin is selected. Then, the measurement of the GSHP system is conducted during the cooling season. Finally, the experimental evaluation of the new strategy is performed. The results show that the free cooling strategy can meet the cooling demand of the case building at the beginning of the cooling season, there is no dewing phenomenon on the floor surface during the floor radiation free cooling period and the average system energy efficiency ratio (EER) (with the value of 49.29) of the free cooling mode is 16.6 times that of active cooling mode. The electricity consumption and operation cost have a great saving potential. The total heat discharged into the ground soil is reduced largely. This will slow the performance deterioration of the GSPH system.

Individual packet deadline delay constrained opportunistic scheduling for large multiuser systems

This work addresses opportunistic distributed multiuser scheduling in the presence of a fixed packet deadline delay constraint. A threshold-based scheduling scheme is proposed which uses the instantaneous channel gain and buffering time of the individual packets to schedule a group of users simultaneously in order to minimize the average system energy consumption while fulfilling the deadline delay constraint for every packet. The multiuser environment is modeled as a continuum of interference such that the optimization can be performed for each buffered packet separately by using a Markov chain where the states represent the waiting time of each buffered packet. We analyze the proposed scheme in the large user limit and demonstrate the delay-energy trade-off exhibited by the scheme. We show that the multiuser scheduling can be broken into a packet-based scheduling problem in the large user limit and the packet scheduling decisions are independent of the deadline delay distribution of the packets.

Maximizing System Energy Efficiency by Exploiting Multiuser Diversity and Loss Tolerance of the Applications

We address the problem of energy efficient scheduling over fading channels for the loss tolerant applications. The proposed scheduling scheme allows dropping of a certain predefined proportion of data packets on the transmitter side. However, there is a hard constraint on the maximum number of successively dropped packets. The scheduler exploits average data loss tolerance to reduce the average system energy expenditure while fulfills the hard constraint on the number of successively dropped packets. We explore the effect of average and successive packet loss constraints on the system energy and characterize the regions where one parameter is more critical as compared to the other in the sense of achieving better energy efficiency. The scheme is analyzed using asymptotically large user limit and the optimized channel¿-dependent dropping thresholds are computed by using combinatorial optimization techniques. The numerical results illustrate the energy efficiency of the scheme as a function of the average and successive packet drop parameters.

Energy-efficient graphical user interface design

Mobile computers, such as cell phones and personal digital assistants (PDAs), have dramatically increased in sophistication. At the same time, the desire of consumers for portability limits batters size. As a result, many researchers have targeted hardware and software energy optimization. However, most of these techniques focus on compute-intensive applications rather than interactive applications, which are dominant in mobile computers. These systems frequently use graphical user interfaces (GUIs) to handle human-computer interaction. This paper is the first to explore how GUIs can be designed to improve system energy efficiency. We investigate how GUI design approaches should be changed to improve system. Energy efficiency and provide specific suggestions to mobile computer designers to enable them to develop more energy-efficient systems. We demonstrate that energy-efficient GUI (E/sup 2/GUI) design techniques can improve the average system energy of three benchmarks (text-viewer, personnel viewer, and calculator) by 26.9, 45.2, and 16.4 percent, respectively. Average performance is simultaneously improved by 23.7, 34.6, and 19.3 percent, respectively.

Quasiperiodic behavior in beam-driven strong Langmuir turbulence

The evolution of unmagnetized beam-driven strong Langmuir turbulence is studied in two dimensions by numerically integrating the Zakharov equations for systems pumped by monochromatic and broadband negative-damping drivers with nonzero central wavenumber. Long-time statistically steady states are reached for which the dependence of the evolution on the driver wavenumber, growth rate, and bandwidth is examined in detail. For monochromatic drivers, a quasiperiodic cycle is found to develop if the driver wavenumber is sufficiently large. In this cycle, energy from the driven mode undergoes a sequence of weak-turbulence backscatter decays, which transfer energy to an approximately isotropic long-wavelength condensate. During this phase, beam-aligned chains of propagating beat waves develop and perpendicular density waves are also excited. Subsequently, nucleation of waves in density cavities causes a series of wave collapses (involving coherent wave–wave interactions) to occur, during which short-wavelength damping reduces the system energy in discrete steps. Finally, the cycle restarts. The characteristic frequency of the quasiperiodic cycle and the average system energy are both approximately proportional to the growth rate. Broadening of the driver in wavenumber tends to degrade the system-wide coherence of the cycle, but its main features appear to survive on the scale of the coherence length of the driver.

Dynamics of the Collinear H+H2 Reaction. I. Probability Density and Flux

The time evolution of the collinear H+H2 reaction as given by classical mechanics and by time-dependent quantum mechanics has been studied. The calculations employed the Porter–Karplus potential surface. The relevant equations of motion were solved to high accuracy by direct numerical integration. The evolution of the quantal probability density in the interaction region of the potential surface is shown in a series of perspective plots. Classical mechanics gives an amazingly good description of the probability density and flux patterns during most of the reaction; however, the classical and quantal descriptions begin to diverge near the end of the reaction. Essentially, the classical reaction terminates before the quantal reaction. The dynamic behavior of the reaction is hydrodynamically turbulent, as shown by transient whirlpool formation on the inside of the reaction path. All results reported in this paper are for one average system energy, namely, 0.65 eV (initial average translational energy = 0.38 eV).