In the tropical regions represented by Hainan,there are abundant solar and thermal resources,and it is relatively suitable for the construction of photovoltaic greenhouse(PVG).However,the construction of PVG still rel...In the tropical regions represented by Hainan,there are abundant solar and thermal resources,and it is relatively suitable for the construction of photovoltaic greenhouse(PVG).However,the construction of PVG still relies mainly on experience and is incapable of quantifying the balance between the photovoltaic(PV)generation and the light requirements for agricultural production.As a result,actual PVGs are primarily PV-based,without carefully considering the needs of agricultural daylighting.To quantify the influence of the design parameters of PVGs and the layout of PV panels on the internal daylighting of serrated PVGs,and to optimize the daylighting design of the roof,this paper utilizes the Design Builder software to establish gradient models for a multi-span serrated-type PVG in tropical regions.Gradient models were established in terms of aspects,namely span,width of longitudinal/transverse daylighting strip,height,roof angle,and photovoltaic panel coverage rate(PCR).Daylighting in the greenhouse of each gradient model was simulated,and with the annual average daily light integral(A_(DLI))and distribution uniformity(DU)as evaluation indicators,the influence of various design parameters on the daylighting inside the greenhouse was quantified.The result reveals that:(1)PCR is the decisive indicator for daylighting in the PVG,and a function between PCR and the A_(DLI) is derived as A_(DLI)=-15.5 PCR+16.841;(2)Increasing the width of longitudinal daylighting strip significantly improves the A_(DLI) and enhances DU while increasing the span has a noticeable effect on improving A_(DLI) but does not significantly enhance DU;(3)Increasing the eave height without changing PCR does not enhance A_(DLI) but effectively improves DU;increasing the transverse daylighting strip and adjusting the roof angle hardly improves A_(DLI).In summary,it is recommended that the optimal span for PVGs in tropical regions be set within the range of 6.5-8.0m,and the eave height be set within the range of 2.5-3.5m.Preferably,the longitudinal daylighting strip with a width ranging from 0.5-0.8m should be installed.Based on the above relationship function,the PCR can be calculated according to the appropriate light demand for the cultivated crops.The daylighting design theory proposed in this paper can provide a theoretical basis and reference for the healthy development of the PV industry in tropical regions.展开更多
To achieve fast, smooth and accurate set point tracking in servo positioning systems, a parameterized design of nonlinear feedback controllers is presented, based on a so-called composite nonlinear feedback （CNF） co...To achieve fast, smooth and accurate set point tracking in servo positioning systems, a parameterized design of nonlinear feedback controllers is presented, based on a so-called composite nonlinear feedback （CNF） control technique. The controller designed here consists of a linear feedback part and a nonlinear part. The linear part is responsible for stability and fast response of the closed-loop system. The nonlinear part serves to increase the damping ratio of closed-loop poles as the controlled output approaches the target reference. The CNF control brings together the good points of both the small and the large damping ratio cases, by continuously scheduling the damping ratio of the dominant closed-loop poles and thus has the capability for superior transient performance, i.e. a fast output response with low overshoot. In the presence of constant disturbances, an integral action is included so as to remove the static bias. An explicitly parameterized controller is derived for servo positioning systems characterized by second-order model. Practical application in a micro hard disk drive servo system is then presented, together with some discussion of the rationale and characteristics of such design. Simulation and experimental results demonstrate the effectiveness of this control design methodology.展开更多
Orthogonal frequency division multiplexing (OFDM) waveform enables radar and communication functions simultaneously, which encounters low angle resolution and poor data rate for traditional single input single output ...Orthogonal frequency division multiplexing (OFDM) waveform enables radar and communication functions simultaneously, which encounters low angle resolution and poor data rate for traditional single input single output (SISO) systems. To solve these problems, an integrated radar and communication system (IRCS) with multiple input multiple output (MIMO) OFDM waveform is proposed. The different limitations of radar and communication in designing such a system are investigated. Then, an optimization problem is devised to obtain suitable system parameters, including the number of subcarriers, subcarrier spacing, number of symbols, pulse repetition frequency (PRF) and length of cyclic prefix (CP). Finally, to satisfy the requirements of both radar and communication, the IRCS parameters are derived in three typical cases. Several numerical results are presented to illustrate the demands of radar and communication, inconsistent or consistent, for the IRCS parameters and the superiority of the proposed system.展开更多
文章研究并解决数据中心的远程内存直接读取(remote direct memory access, RDMA)技术的网络拥塞控制问题。针对主流拥塞控制算法数据中心量化拥塞通知(data center quantized congestion notification, DCQCN)的收敛速度慢和缺乏硬件...文章研究并解决数据中心的远程内存直接读取(remote direct memory access, RDMA)技术的网络拥塞控制问题。针对主流拥塞控制算法数据中心量化拥塞通知(data center quantized congestion notification, DCQCN)的收敛速度慢和缺乏硬件实现方案的不足,提出可参数硬件化的数据中心量化拥塞通知(parameterized DCQCN,DCQCN-p)算法,该算法通过优化拥塞流的速度因子a、g调整速度比例Rc,并通过电路设计减少降速的频次;通过建立算法模型和搭建网络仿真NS-3平台,对比DCQCN-p算法在面临拥塞时单个调度流速度调整的性能以及多个调度流并发情况下的时延和吞吐量。仿真结果表明:在单个流面临拥塞时,DCQCN-p算法的数据传输速率比DCQCN算法的提高了50%;DCQCN-p算法在链路上最小速率为13.28 Gbit/s,相较于DCQCN、TIMELY、数据中心传输控制协议(data center transmission control protocol, DCTCP)算法,分别增长了24%、48%、23%;DCQCN-p算法(方差65%)的带宽分配公平性相较于TIMELY算法(方差216%)和DCTCP算法(方差191%)表现出显著的性能提升。展开更多
为提高电信网设备应对异常信令访问的检测能力,需对64K信令进行分析并处理。为了提高解析效率并满足近年来相关产品对自主可控越来越高的要求,设计了一种基于国产现场可编程门阵列(Field Programmable Gate Array, FPGA)的信令解析方案...为提高电信网设备应对异常信令访问的检测能力,需对64K信令进行分析并处理。为了提高解析效率并满足近年来相关产品对自主可控越来越高的要求,设计了一种基于国产现场可编程门阵列(Field Programmable Gate Array, FPGA)的信令解析方案,给出了方案的总体设计思路,并对FPGA实现的功能模块进行详细说明。对系统进行设计时,采用模块化参数化方法以及在关键环节添加状态参数,提高了可扩展性并可以对模块内部运行状态进行监控,最终实现了对信令高效且灵活的解析,主要器件等均为国产。经过测试,可以实现STM-1(STM-Synchronous Transfer Module-1)数据的接入、串并转换、HDLC(High-level Data Link Control)解帧等功能,完成32路64K信令的并发处理,模块运行状态可查可看,达到了预期的效果。以STM-1为例,基于现有功能的模块化设计,可以平滑地扩展到STM-4、STM-16的应用。展开更多
基金2024 Science and Technology Commissioner Service Group's Emergency Science and Technology Research Project for Wind Disaster Relief in Hainan Province(ZDYF2024YJGG002-8)China Huaneng Group Co.,Ltd.Headquarters Technology Project,Optimization of Photovoltaic Vegetable Greenhouse Structure and Research on Planting Agronomy in Tropical Regions(HNKJ22-HF77)。
文摘In the tropical regions represented by Hainan,there are abundant solar and thermal resources,and it is relatively suitable for the construction of photovoltaic greenhouse(PVG).However,the construction of PVG still relies mainly on experience and is incapable of quantifying the balance between the photovoltaic(PV)generation and the light requirements for agricultural production.As a result,actual PVGs are primarily PV-based,without carefully considering the needs of agricultural daylighting.To quantify the influence of the design parameters of PVGs and the layout of PV panels on the internal daylighting of serrated PVGs,and to optimize the daylighting design of the roof,this paper utilizes the Design Builder software to establish gradient models for a multi-span serrated-type PVG in tropical regions.Gradient models were established in terms of aspects,namely span,width of longitudinal/transverse daylighting strip,height,roof angle,and photovoltaic panel coverage rate(PCR).Daylighting in the greenhouse of each gradient model was simulated,and with the annual average daily light integral(A_(DLI))and distribution uniformity(DU)as evaluation indicators,the influence of various design parameters on the daylighting inside the greenhouse was quantified.The result reveals that:(1)PCR is the decisive indicator for daylighting in the PVG,and a function between PCR and the A_(DLI) is derived as A_(DLI)=-15.5 PCR+16.841;(2)Increasing the width of longitudinal daylighting strip significantly improves the A_(DLI) and enhances DU while increasing the span has a noticeable effect on improving A_(DLI) but does not significantly enhance DU;(3)Increasing the eave height without changing PCR does not enhance A_(DLI) but effectively improves DU;increasing the transverse daylighting strip and adjusting the roof angle hardly improves A_(DLI).In summary,it is recommended that the optimal span for PVGs in tropical regions be set within the range of 6.5-8.0m,and the eave height be set within the range of 2.5-3.5m.Preferably,the longitudinal daylighting strip with a width ranging from 0.5-0.8m should be installed.Based on the above relationship function,the PCR can be calculated according to the appropriate light demand for the cultivated crops.The daylighting design theory proposed in this paper can provide a theoretical basis and reference for the healthy development of the PV industry in tropical regions.
文摘To achieve fast, smooth and accurate set point tracking in servo positioning systems, a parameterized design of nonlinear feedback controllers is presented, based on a so-called composite nonlinear feedback （CNF） control technique. The controller designed here consists of a linear feedback part and a nonlinear part. The linear part is responsible for stability and fast response of the closed-loop system. The nonlinear part serves to increase the damping ratio of closed-loop poles as the controlled output approaches the target reference. The CNF control brings together the good points of both the small and the large damping ratio cases, by continuously scheduling the damping ratio of the dominant closed-loop poles and thus has the capability for superior transient performance, i.e. a fast output response with low overshoot. In the presence of constant disturbances, an integral action is included so as to remove the static bias. An explicitly parameterized controller is derived for servo positioning systems characterized by second-order model. Practical application in a micro hard disk drive servo system is then presented, together with some discussion of the rationale and characteristics of such design. Simulation and experimental results demonstrate the effectiveness of this control design methodology.
基金supported by the National Natural Science Foundation of China(6123101761671352)
文摘Orthogonal frequency division multiplexing (OFDM) waveform enables radar and communication functions simultaneously, which encounters low angle resolution and poor data rate for traditional single input single output (SISO) systems. To solve these problems, an integrated radar and communication system (IRCS) with multiple input multiple output (MIMO) OFDM waveform is proposed. The different limitations of radar and communication in designing such a system are investigated. Then, an optimization problem is devised to obtain suitable system parameters, including the number of subcarriers, subcarrier spacing, number of symbols, pulse repetition frequency (PRF) and length of cyclic prefix (CP). Finally, to satisfy the requirements of both radar and communication, the IRCS parameters are derived in three typical cases. Several numerical results are presented to illustrate the demands of radar and communication, inconsistent or consistent, for the IRCS parameters and the superiority of the proposed system.
文摘文章研究并解决数据中心的远程内存直接读取(remote direct memory access, RDMA)技术的网络拥塞控制问题。针对主流拥塞控制算法数据中心量化拥塞通知(data center quantized congestion notification, DCQCN)的收敛速度慢和缺乏硬件实现方案的不足,提出可参数硬件化的数据中心量化拥塞通知(parameterized DCQCN,DCQCN-p)算法,该算法通过优化拥塞流的速度因子a、g调整速度比例Rc,并通过电路设计减少降速的频次;通过建立算法模型和搭建网络仿真NS-3平台,对比DCQCN-p算法在面临拥塞时单个调度流速度调整的性能以及多个调度流并发情况下的时延和吞吐量。仿真结果表明:在单个流面临拥塞时,DCQCN-p算法的数据传输速率比DCQCN算法的提高了50%;DCQCN-p算法在链路上最小速率为13.28 Gbit/s,相较于DCQCN、TIMELY、数据中心传输控制协议(data center transmission control protocol, DCTCP)算法,分别增长了24%、48%、23%;DCQCN-p算法(方差65%)的带宽分配公平性相较于TIMELY算法(方差216%)和DCTCP算法(方差191%)表现出显著的性能提升。
文摘为提高电信网设备应对异常信令访问的检测能力,需对64K信令进行分析并处理。为了提高解析效率并满足近年来相关产品对自主可控越来越高的要求,设计了一种基于国产现场可编程门阵列(Field Programmable Gate Array, FPGA)的信令解析方案,给出了方案的总体设计思路,并对FPGA实现的功能模块进行详细说明。对系统进行设计时,采用模块化参数化方法以及在关键环节添加状态参数,提高了可扩展性并可以对模块内部运行状态进行监控,最终实现了对信令高效且灵活的解析,主要器件等均为国产。经过测试,可以实现STM-1(STM-Synchronous Transfer Module-1)数据的接入、串并转换、HDLC(High-level Data Link Control)解帧等功能,完成32路64K信令的并发处理,模块运行状态可查可看,达到了预期的效果。以STM-1为例,基于现有功能的模块化设计,可以平滑地扩展到STM-4、STM-16的应用。
