共查询到20条相似文献，搜索用时 15 毫秒
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The photovoltaic components of a hybrid photovoltaic thermal (PV/T) system are combined with a solar thermal collector, which generates both thermal and electrical energy simultaneously with a higher integrated efficiency. A three dimensional steady model of the concentrating solar PV/T system which has a plate type metallic thermal collector with a serpentine rectangular channel is developed. The processes of photovoltaic and thermal transformation and heat transfer in the PV/T collector are calculated and simulated. The effects of the optical concentrating ratio, coolant mass flow rate, ambient air velocity and glass cover on both thermal and electrical performance of the collector are presented and discussed. 相似文献
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In order to solve the speed estimation problems of speed sensorless vector-controlled induction motor drives, the paper presents two speed estimation schemes based on neural network mode identification theory. The advantages of each scheme are discussed and the simulation results show that the estimated speed can trace the actual speed better (even under the circumstances of load variation or speed step variation). Also, these schemes are not sensitive to the variations of motor parameters and the effect of iron loss. Therefore, the proposed neural network based on speed sensorless vector-controlled induction motor drives have good performance in stady-state and transient-state operation. 相似文献
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Poly-generation of cooling, heating and power performance analysis of PV radiant panel PV/T system 
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下载免费PDF全文 A combined cooling, heating and power mono-silicon solar photovoltaic radiant panel (PV/R) is proposed, which compounds the radiant panel with the PV module. The PV operating temperature is decreased through the internal cycling of liquid pipe of radiant panel. Thus the power efficiency of PV module is increased, at the same time, the heat of PV using for heating can be recollected. While at night, the cooling used for the daytime is collected through the nocturnal cooling storage. In the experiment testing, the PV/R not only increases the power efficiency by 8%~16%, but obtains the heating efficiency by 45% and gets the cooling capacity of 40~80 W/m 2. 相似文献
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In order to improve waveform performance of light HVDC system, a lot of switches which operate in high frequency are used, which causes large switching losses and results high cost. A new Buck type voltage source converter(BVSC) is proposed. The new BVSC comprises a dual-buck converter and a three-phase inverter operating in grid frequency. Only two high frequency switches are used, which results good output waveform performance. In order to reduce the high frequency switching losses, a novel improved double-frequency Buck type voltage source converter(DBVSC) is also proposed. An additional dual-Buck converter is added to the BVSC, the added dual-Buck converter deals with the fundamental power that operates in low frequency, and BVSC only deals with harmonic power that operates in high frequency. The output waveform is enhanced and the switching losses are reduced in DBVSC, and the power rating is also increased. The DBVSC is very suitable for large power rating application. The one cycle control theory is adopted to control the proposed DBVSC with analog circuit, which is very simple. The proposed DBVSC and control method are verified by simulation. 相似文献
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Transmission Control Protocol(TCP) is tuned to perform well in wired networks or environment with low bit errors where packet losses occur mostly because of congestion.However,when TC Pis operated in high BER environment and suffers from significant losses due to bit errors,it does not make the best use of the available bandwidth of links because TC Phavles its current congestion window blindly.As a result,the performance of TC Pwould be deteriorated very much.Recently,the use of enhanced bandwidth estimation procedures within the congestion control scheme of TC Pwas proposed as a way of improving TC Pperformance over links affected by random loss.This paper first analyzes the problems faced by every bandwidth estimation algorithm implemented at the sender side of a TCP connection.Some proposed estimation algorithms,accuracy and performance are estimated.At the same time,the authors discuss the relationshi Pbetweent the bandwidth estimation accuracy and the fairness of protocol.Finally,this paper point out the further work should be done in future. 相似文献
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This paper proposes a control strategy for the optimal control of the outsourcing production inventory system based on production point and production batch. The statistical probability distribution is used to describe the uncertainty of the production capacity of cooperative enterprises and the transportation time. The optimization model of the control parameters is developed with random production capacity for cooperative enterprises and random transportation time in order to minimize the holding cost,setup cost as well as the cost of production capacity waste. A simulation-based control parameters optimization algorithm is designed to solve the proposed model. The control strategy of production inventory system and the control parameters optimization algorithm proposed are validated by an example. We analyze the influence of the variation of the production point and production batch to the performance of the outsourcing production inventory system. 相似文献
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Traditional mineral resource visualized dynamic estimation and its application in 3D geological space 总被引：1，自引：0，他引：1
A new method for traditional mineral resource visualized dynamic estimation in 3D geological space is proposed, which is adaptive to the characteristics of resource exploitation and reserve classification in China. The method follows the daily workflow of mine exploitation, improves the traditional method for resource estimation by 3D visualization technologies, and replaces abstract regular geometries with real 3D geological models. Thus, the traditional method for resource estimation realizes visualization in the whole workflow of mine exploitation. The application results to some real mines show the estimation results are mainly affected by the spatial location, shape and thickness of mineral blocks and goaf. If the resource dynamic estimation is carried out by constructing 3D mineral models in consistent with real exploitation project, the accuracy of the traditional method can be effectively improved. 相似文献
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For the requirement of building up the battery management system (BMS) of hybrid vehicles(HEVs), the real time measurement and estimation of charge (SOC) of the Ni MH batteries are investigated, because the popular SOC definition is unsuitable under the condition of variable current discharge. The origin of this kind unsuitability are analyzed ,and the characteristics and existing problems of different kinds of SOC measuring methods are compared. On the basis of mentioned above, some corrections are given to the popular SOC definition, and the new conception of SOC is proposed. The corrected definition of SOC is suitable for the real time SOC estimation under the variable current condition of the batteries used in HEVs. Based on the corrected SOC definition, the computational model of the new SOC is built and simulated. Satisfactory result has been obtained from comparisons of the simulating results, which shows that the theoretical model provides a basis for optimizing the adaptation of power system to the hybrid vehicles (HEVs). 相似文献
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In the intelligent control system with microprocessor controlling, the development of embedded software requires some simple and practical intelligent control algorithms. The algorithms can not only make the control system's performance good, but also meet the demands of real time control. Aim at the problem, it is presented that a fuzzy controller with simulating human intelligent control. The structure , control algorithms and the simulation results of the controller are given. The simulation and application show that the fuzzy controller with simulating human intelligent control has many advantages such as fast response, less overshoot, good robust. The design of the controller does not need the accuracy math model of controlled object. 相似文献
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For the shortage of tracking ability against fast fading channel of the existing pilot structures and channel estimation algorithms in OFDM combined with time division multiplexing (OFDM/TDM) system, an improved channel estimation algorithm is proposed. The channel transfer functions are obtained by estimating the channel properties with two adjacent time domain multiplexing (TDM) pilot sequences, while the channel state information of the OFDM/TDM symbols is obtained with interpolation Combined with frequency domain equalization based on minimum mean square error (MMSE-FDE), the proposed algorithm can significantly compensate the path loss over fast fading channels. Simulation results show that, compared with the existing channel estimation algorithms, the proposed algorithm can achieve better performance, which is not only capable of dealing with slow fading channels, but also has a better tracking ability against fast fading channels with the same data transmission efficiency. 相似文献
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为实现对无土栽培营养液中影响作物生长的各重要因子的精准测量与控制,笔者研制了一种基于阿里云的温室无土栽培营养液信息监测系统。该系统主要包括采集模块、控制模块、云平台和应用终端4个部分。首先利用传感器实时测量营养液的电导率、酸碱度、液温、液位和含氧量等影响因子信息,然后进行数据整合处理,并通过无线通信模块传送至控制模块及阿里云平台进行数据保存,最后通过Web端实时监控营养液各信息变化。研究结果表明,该系统能够实时准确监测营养液的信息,合理反馈供给作物所需营养液信息,达到功能设计要求,而且系统成本低,具有一定的实用价值。 相似文献
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针对模糊控制系统中切换时延较长和切换次数较多的问题,研究了一种基于模糊控制系统的垂直切换判决算法。在基于信号强度判决时将RSS作为门限值,提高系统判决能力;同时,将网络参数和服务类型作为判决因素,结合层次分析法引入并行的模糊控制系统,缩短了切换判决的时间、选择适合用户的最佳网络,做出垂直切换。仿真结果表明,该算法减少了切换次数,降低了切换时延,增强了系统的性能。与传统的切换算法相比较,该算法对切换的判决因素考虑的更全面,兼顾了用户终端的使用环境及成本问题,有效地保证了网络的服务质量。 相似文献
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The combination of the measured real time state acquisition from the process with predictive process for the fature state is used to predicate the variable tendency for process state. This method is useful to avoid delay and enhance real time ability of the control information of the expert system. Also a described knowledge and structure of real time process state are proposed. This system can be applied to other kind of practice systems with slow time variable, uncertainty and delay. 相似文献
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Photovoltaic power generation is considered to be one of the most promising power generation forms. It is difficult to accurately assess the reliability of the photovoltaic system (PVS) for the volatility and intermittent of the light intensity. By analyzing PVS component failure modes and their impacts on PVS output power, the reliability model of PVS is built. Then the probability model of PVS output power is presented by considering both illumination uncertainty and PVS component random faults. According to the influence of components random faults outside the intentional islands on the reliability of load points inside the intentional islands, the concepts of repair zone, isolation zone and zero zone are defined. Furthermore, by considering the fail-operation of breaker and fuse, the concept for zone hierarchy is proposed, and the analytical formulas to calculate reliability indices of the load points inside the intentional islands are deduced. The application of the presented reliability evaluation model is clarified using a typical example to show the practicality and validity of the proposed approach. 相似文献
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Aiming at real time diagnostic knowledge accumulation and updating in intelligent diagnostic system, to simulate the process experts accumulate and update fault diagnostic knowledge, a new real time diagnostic knowledge self learning model is proposed based on pattern comparing and updating. Abnormal distribution test of hypothesis is used to compare real time equipment fault pattern to equipment normal pattern of contingent knowledge. The algorithm of sample size estimation algorithm is used to calculate the number of samples which is used to obtain necessary diagnostic efficiency. Real time model updating algorithm is used to adjust the diagnostic knowledge model to actual equipment on the spot. Analysis to actual test data of equipment shows that the method could achieve new diagnostic knowledge accumulation and be adaptive to actual equipment on the spot. 相似文献
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The intense coupled and nonlinear behaviors were observed on the tall long span tower line systems which were under the icing and wind loads in heavy icing areas. A set of stiffness equations of insulator, conductor and boundary conditions was deduced. Taking the ±800 kV UHV DC transmission line from Xiangjiaba to Shanghai as an example, the simplified numerical model of transmission tower, conductor, insulator and constraint was developed. The long span transmission tower line system models under seven loads conditions were analyzed by static nonlinear methods. It was found that the P Δ effect of tower components was small when the covered ice was uniformly distributed. The unbalanced wire loads on the tower would lead to twist effect when the covered ice was uneven distributed. The axial forces, moments at restraint nodes and the longest cantilever member were greatly affected by the P Δ effect, under which the unfavorable effect on the structure should be considered. 相似文献
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光储微电网混合储能系统的控制策略及开关优化 总被引：1，自引：0，他引：1
传统光储微电网混合储能系统控制策略将蓄电池视为容量无限大的理想元件,而实际上蓄电池容量有限,当蓄电池剩余电量达到阈值无法正常工作时传统控制策略将不适用。在二阶低通滤波法的基础上提出一种光储微电网混合储能系统的新型控制策略,同时考虑超级电容与蓄电池的剩余电量,根据储能元件的荷电状态调整储能元件输出电流参考值,维持储能元件剩余电量,但在极端天气情况下,仍需与储能元件保护开关相配合。由于采用传统储能元件保护开关的储能系统需独立的充放电电路,存在成本较高、充放电不连续等问题,因此,对储能元件的保护开关进行了改进,利用开关与二极管并联使其具有4种工作状态,在储能元件剩余电量达到阈值时,可自动恢复电量,降低了成本,提高了并网输出电能质量。最后结合新型控制策略与改进的保护开关,提出整体的混合储能系统控制方案,并用Matlab/Simulink对其进行仿真验证,结果证明了所提方法的正确性与可行性。 相似文献
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基于无线传感器网络的鱼塘监控系统 总被引：3，自引：1，他引：2
本文设计了基于无线传感器网络的鱼塘实时在线智能监控系统,有效解决了传统的鱼塘观测手段存在的问题,例如：费时费力、步骤复杂、成本高等。该系统在鱼塘的监测区域中利用无线传感器节点,测得该区域中的温度和溶氧量,并通过Zigbee网络将数据传输到终端控制系统,控制系统作出判断并发出报警信号和控制增氧机的状态。系统中以MSP430和XBEE模块为核心芯片,能够实时在线监测鱼塘中的一些参数,例如温度、溶氧量等。同时该系统还可以进一步扩展使用GPRS或3G网络实现远程监控。 相似文献