This paper investigates subcarrier and power allocation in a multi-UAV OFDM system.The study considers a practical scenario,where certain subcarriers are unavailable for dynamic subcarrier allocation,on account of pre...This paper investigates subcarrier and power allocation in a multi-UAV OFDM system.The study considers a practical scenario,where certain subcarriers are unavailable for dynamic subcarrier allocation,on account of pre-allocation for burst transmissions.We first propose a novel iterative algorithm to jointly optimize subcarrier and power allocation,so as to maximize the sum rate of the uplink transmission in the multiUAV OFDM system.The key idea behind our solution is converting the nontrivial allocation problem into a weighted mean square error(MSE) problem.By this means,the allocation problem can be solved by the alternating optimization method.Besides,aiming at a lower-complexity solution,we propose a heuristic allocation scheme,where subcarrier allocation and transmit power allocation are separately optimized.In the heuristic scheme,closedform solution can be obtained for power allocation.Simulation results demonstrate that in the presence of stretched subcarrier resource,the proposed iterative joint optimization algorithm can significantly outperform the heuristic scheme,offering a higher sum rate.展开更多
Register allocation in high-level circuit synthesis is important not only for reducing area, delay, and power overheads, but also for improving the testability of the synthesized circuits. This paper presents an impro...Register allocation in high-level circuit synthesis is important not only for reducing area, delay, and power overheads, but also for improving the testability of the synthesized circuits. This paper presents an improved register allocation algorithm that improves the testability called weighted graph-based balanced register allocation for high-level circuit synthesis. The controllability and observability of the registers and the self-loop elimination are analyzed to form a weighted conflict graph, where the weight of the edge between two nodes denotes the tendency of the two variables to share the same register. Then the modified desaturation algorithm is used to dynamically modify the weights to obtain a final balanced register allocation which improves the testability of the synthesized circuits a higher fault coverage than other algorithms with Tests on some benchmarks show that the algorithm gives less area overhead and even less time delay.展开更多
Radio Cognitive (RC) is the new concept introduced to improve spectrum utilization in wireless communication and present important research field to resolve the spectrum scarcity problem. The powerful ability of CR to...Radio Cognitive (RC) is the new concept introduced to improve spectrum utilization in wireless communication and present important research field to resolve the spectrum scarcity problem. The powerful ability of CR to change and adapt its transmit parameters according to environmental sensed parameters, makes CR as the leading technology to manage spectrum allocation and respond to QoS provisioning. In this paper, we assume that the radio environment has been sensed and that the SU specifies QoS requirements of the wireless application. We use genetic algorithm (GA) and propose crossover method called Combined Single-Heuristic Crossover. The weighted sum multi-objective approach is used to combine performance objectives functions discussed in this paper and BER approximate formula is considered.展开更多
无线网络中出现的频谱稀缺、能源受限和干扰等各种问题,已成为国内外研究学者的研究热点。为此,提出一种基于能量收集衬底式的认知无线携能通信(Simultaneous Wireless Information and Power Transfer,SWIPT)网络,称为认知SWIPT或二级S...无线网络中出现的频谱稀缺、能源受限和干扰等各种问题,已成为国内外研究学者的研究热点。为此,提出一种基于能量收集衬底式的认知无线携能通信(Simultaneous Wireless Information and Power Transfer,SWIPT)网络,称为认知SWIPT或二级SWIPT网络。该通信网络采用认知无线电技术,允许无线能量传输和无线信息传输与现有的主系统共享相同的频谱,能将主用户对二级用户的干扰转化为有效能量。在温度干扰约束条件下,通过联合优化时间分配和功率控制,最大限度地提高认知SWIPT网络的加权吞吐量,同时保证主系统的通信质量。利用MATLAB软件进行仿真,分析和比较所提联合优化方案与等时间分配方案,仿真结果表明,前者显著提高了频谱效率和能量利用率,明显优于后者。展开更多
Determining the location of earthquake emergency shelters and the allocation of affected population to them are key issues that face shelter planning and emergency management. To solve this emergency shelter location...Determining the location of earthquake emergency shelters and the allocation of affected population to them are key issues that face shelter planning and emergency management. To solve this emergency shelter location–allocation problem, evacuation time and the construction cost of shelters—both influenced by the evacuation population size and its spatial distribution—are two important considerations. In this article, a mathematical model with two objectives—to minimize total weighted evacuation time(TWET) and total shelter area(TSA)—is allied with a modified particle swarm optimization algorithm to address the problem. The relationships between evacuation population size, evacuation time, and total shelter area are examined using Jinzhan Town in Chaoyang District of Beijing, China, as a case study. The results show that TWET has a power function relationship with TSA under different population size scenarios, and a linear function applies between evacuation population and TWET under different TSAs. The joint relationships of TSA, TWET, and population size show that TWET increases with population increase and TSA decrease, and compared with TSA, population influences TWET more strongly. Given a reliable projection of population change and spatial planning of a study area, this method can be useful for government decision making on the location of earthquake emergency shelters and on the allocation of evacuees to those shelters.展开更多
了解在不同生态系统中植物生物量分配的调控机制是阐明植物适应性策略的重要理论基础。目前,虽然生境条件对植物生物量分配的影响已被广泛研究,但对植物群落性状和功能(plant community traits and functions,PCTF)如何调控生物量分配,...了解在不同生态系统中植物生物量分配的调控机制是阐明植物适应性策略的重要理论基础。目前,虽然生境条件对植物生物量分配的影响已被广泛研究,但对植物群落性状和功能(plant community traits and functions,PCTF)如何调控生物量分配,特别是在高寒草地生态系统中的研究却较少。本研究计算了在群落水平上的5种叶片功能性状的群落加权平均值(community-weighted means,CWM),并利用相关分析、方差分解分析和结构方程模型探讨了PCTF与生物量权衡之间的关系。研究结果发现,高寒草甸(alpine meadow,AM)和高寒草原(alpine steppe,AS)的权衡值都大于零,但两者存在显著差异,AM的权衡值(0.203)明显高于AS(0.088)。此外,决定AS生物量分配的关键因素是物种丰富度(0.69)和叶片干物质含量(CWM_(LDMC),0.42),而在AM中,关键因素是叶片干物质含量(CWM_(LDMC),0.48)和叶片碳含量(CWM_(LC)-0.45)。值得注意的是,无论AS中的CWM_(LDMC)和物种丰富度,还是AM中的CWM_(LDMC)和CWM_(LC)都主要受气候因素中的降水调节。总而言之,降水往往通过对PCTF的影响来调控高寒草地的生物量分配,因此强调了PCTF在调节降水梯度上植物生物量分配策略的重要性。展开更多
基金supported by China NSF Grants(61631020)the Fundamental Research Funds for the Central Universities(NP2018103,NE2017103,NC2017003)
文摘This paper investigates subcarrier and power allocation in a multi-UAV OFDM system.The study considers a practical scenario,where certain subcarriers are unavailable for dynamic subcarrier allocation,on account of pre-allocation for burst transmissions.We first propose a novel iterative algorithm to jointly optimize subcarrier and power allocation,so as to maximize the sum rate of the uplink transmission in the multiUAV OFDM system.The key idea behind our solution is converting the nontrivial allocation problem into a weighted mean square error(MSE) problem.By this means,the allocation problem can be solved by the alternating optimization method.Besides,aiming at a lower-complexity solution,we propose a heuristic allocation scheme,where subcarrier allocation and transmit power allocation are separately optimized.In the heuristic scheme,closedform solution can be obtained for power allocation.Simulation results demonstrate that in the presence of stretched subcarrier resource,the proposed iterative joint optimization algorithm can significantly outperform the heuristic scheme,offering a higher sum rate.
基金Supported by the National Key Basic Research and Development(973) Program of China (No. 2005CB321604)the National Natural Science Foundation of China (No. 60633060)
文摘Register allocation in high-level circuit synthesis is important not only for reducing area, delay, and power overheads, but also for improving the testability of the synthesized circuits. This paper presents an improved register allocation algorithm that improves the testability called weighted graph-based balanced register allocation for high-level circuit synthesis. The controllability and observability of the registers and the self-loop elimination are analyzed to form a weighted conflict graph, where the weight of the edge between two nodes denotes the tendency of the two variables to share the same register. Then the modified desaturation algorithm is used to dynamically modify the weights to obtain a final balanced register allocation which improves the testability of the synthesized circuits a higher fault coverage than other algorithms with Tests on some benchmarks show that the algorithm gives less area overhead and even less time delay.
文摘Radio Cognitive (RC) is the new concept introduced to improve spectrum utilization in wireless communication and present important research field to resolve the spectrum scarcity problem. The powerful ability of CR to change and adapt its transmit parameters according to environmental sensed parameters, makes CR as the leading technology to manage spectrum allocation and respond to QoS provisioning. In this paper, we assume that the radio environment has been sensed and that the SU specifies QoS requirements of the wireless application. We use genetic algorithm (GA) and propose crossover method called Combined Single-Heuristic Crossover. The weighted sum multi-objective approach is used to combine performance objectives functions discussed in this paper and BER approximate formula is considered.
文摘无线网络中出现的频谱稀缺、能源受限和干扰等各种问题,已成为国内外研究学者的研究热点。为此,提出一种基于能量收集衬底式的认知无线携能通信(Simultaneous Wireless Information and Power Transfer,SWIPT)网络,称为认知SWIPT或二级SWIPT网络。该通信网络采用认知无线电技术,允许无线能量传输和无线信息传输与现有的主系统共享相同的频谱,能将主用户对二级用户的干扰转化为有效能量。在温度干扰约束条件下,通过联合优化时间分配和功率控制,最大限度地提高认知SWIPT网络的加权吞吐量,同时保证主系统的通信质量。利用MATLAB软件进行仿真,分析和比较所提联合优化方案与等时间分配方案,仿真结果表明,前者显著提高了频谱效率和能量利用率,明显优于后者。
基金funded by the Ministry of Science and Technology, China (Grant Number: 2016YFA0602404)Ministry of Education and State Administration of Foreign Experts Affairs, China (Grant Number: B08008)National Natural Science Foundation of China (Grant Number: 41201547)
文摘Determining the location of earthquake emergency shelters and the allocation of affected population to them are key issues that face shelter planning and emergency management. To solve this emergency shelter location–allocation problem, evacuation time and the construction cost of shelters—both influenced by the evacuation population size and its spatial distribution—are two important considerations. In this article, a mathematical model with two objectives—to minimize total weighted evacuation time(TWET) and total shelter area(TSA)—is allied with a modified particle swarm optimization algorithm to address the problem. The relationships between evacuation population size, evacuation time, and total shelter area are examined using Jinzhan Town in Chaoyang District of Beijing, China, as a case study. The results show that TWET has a power function relationship with TSA under different population size scenarios, and a linear function applies between evacuation population and TWET under different TSAs. The joint relationships of TSA, TWET, and population size show that TWET increases with population increase and TSA decrease, and compared with TSA, population influences TWET more strongly. Given a reliable projection of population change and spatial planning of a study area, this method can be useful for government decision making on the location of earthquake emergency shelters and on the allocation of evacuees to those shelters.
基金the National Science Foundation of China(41871040)the Second Tibetan Plateau Scientific Expedition and Research(2019QZKK0405)Joint Research Project of Three-River-Resource National Park funded by the Chinese Academy of Sciences and Qinghai Provincial People's Government(LHZX-2020-08).
文摘了解在不同生态系统中植物生物量分配的调控机制是阐明植物适应性策略的重要理论基础。目前,虽然生境条件对植物生物量分配的影响已被广泛研究,但对植物群落性状和功能(plant community traits and functions,PCTF)如何调控生物量分配,特别是在高寒草地生态系统中的研究却较少。本研究计算了在群落水平上的5种叶片功能性状的群落加权平均值(community-weighted means,CWM),并利用相关分析、方差分解分析和结构方程模型探讨了PCTF与生物量权衡之间的关系。研究结果发现,高寒草甸(alpine meadow,AM)和高寒草原(alpine steppe,AS)的权衡值都大于零,但两者存在显著差异,AM的权衡值(0.203)明显高于AS(0.088)。此外,决定AS生物量分配的关键因素是物种丰富度(0.69)和叶片干物质含量(CWM_(LDMC),0.42),而在AM中,关键因素是叶片干物质含量(CWM_(LDMC),0.48)和叶片碳含量(CWM_(LC)-0.45)。值得注意的是,无论AS中的CWM_(LDMC)和物种丰富度,还是AM中的CWM_(LDMC)和CWM_(LC)都主要受气候因素中的降水调节。总而言之,降水往往通过对PCTF的影响来调控高寒草地的生物量分配,因此强调了PCTF在调节降水梯度上植物生物量分配策略的重要性。
