Maximum power point tracker based on maximum power point resistance modeling

This paper presents a new, simple, accurate, and inexpensive practical methodology and experimental solution for the modeling of conventional (domestic and commercial facilities) photovoltaic generators (PVG), so that they can work at their maximum power point (MPP). The PVG may be a panel, an array of panels, or a photovoltaic field. As a starting restriction (actual) it has to be assumed that it is not possible to isolate the PVG variables dependence (mainly current, voltage, and hence power) with solar radiation and temperature, because they are highly correlated. This methodology proposes the modeling facility on its MPP by its MPP resistance (R_MPP = V_MPP/I_MPP), being V_MPP and I_MPP the voltage and current of the PVG, respectively, at its MPP. The analysis shows, by simulation first and then experimentally, that R_MPP does not present significant temperature dependencies, at least in the usual range. This important result allows us to model the PVG only in terms of solar radiation. From a set of experimental data, different models to estimate R_MPP are proposed. The obtained results are very accurate. These models allow an immediate practical application that it is also developed in the paper: MPP tracker (MPPT) design by the calculation of the DC/DC converter duty cycle which places the PVG at its MPP directly and continuously. This new methodology and experimental system has been registered in the Spanish Patent and Trademark Office with the number P201530352. Copyright © 2015 John Wiley & Sons, Ltd.     

Generators by the quadratic exponential method

Based on the quadratic exponential method, this paper constructs two types of generators over finite field Fq, the digital quadratic exponential generator and quadratic exponential pseudorandom vector generator. We investigate the distribution of the sequence generated by the generators, and present results about their one dimensional discrepancy. The proofs are based on the estimate of certain character sum over Fq. Ift is the least period of the sequence and t≥q^1/2＋2c, then the bound of the discrepancy is O（t^-1/4q^1/8＋τ logq） for any ε 〉 0. It shows that the sequence is asymptotically uniformly distributed.     

三嗪类化合物的合成及其产酸性能研究

合成了一系列的三嗪类光生酸剂1a—1e,确定了它们的结构,并对1e在乙腈溶剂中365和405nm光下的曝光分解产酸性能进行了初步的定量研究.结果表明,在测定浓度范围内分解量子产率和产酸量子产率基本上都不随浓度的变化而变化,在405nm光下比在365nm光下有更高的分解和产酸量子效率.有关这类化合物的光生酸性能与曝光波长的关系正在进一步研究中.     

Geometry Optimization of Thermoelectric Modules: Deviation of Optimum Power Output and Conversion Efficiency

Besides the material research in the field of thermoelectrics, the way from a material to a functional thermoelectric (TE) module comes alongside additional challenges. Thus, comprehension and optimization of the properties and the design of a TE module are important tasks. In this work, different geometry optimization strategies to reach maximum power output or maximum conversion efficiency are applied and the resulting performances of various modules and respective materials are analyzed. A Bi₂Te₃-based module, a half-Heusler-based module, and an oxide-based module are characterized via FEM simulations. By this, a deviation of optimum power output and optimum conversion efficiency in dependence of the diversity of thermoelectric materials is found. Additionally, for all modules, the respective fluxes of entropy and charge as well as the corresponding fluxes of thermal and electrical energy within the thermolegs are shown. The full understanding and enhancement of the performance of a TE module may be further improved.     

An improved evaluation of the neutron background in the PandaX-Ⅱ experiment

In dark matter direct detection experiments,neutron is a serious source of background,which can mimic the dark matter-nucleus scattering signals.In this paper,we present an improved evaluation of the neutron background in the PandaX-II dark matter experiment by a novel approach.Instead of fully relying on the Monte Carlo simulation,the overall neutron background is determined from the neutron-induced high energy signals in the data.In addition,the probability of producing a dark-matter-like background per neutron is evaluated with a complete Monte Carlo generator,where the correlated emission of neutron(s)andγ(s)in the(α,n)reactions and spontaneous fissions is taken into consideration.With this method,the neutron backgrounds in the Run 9(26-ton-day)and Run 10(28-ton-day)data sets of PandaX-II are estimated to be(0.66±0.24)and(0.47±0.25)events,respectively.     

引信点目标视频回波模拟器距离模拟电路设计

针对某伪码调相PD引信点目标视频回波模拟器的要求,提出了基于现场可编程门阵列（FPGA）与片外精密数控可编程延时线两级延时技术的引信点目标视频回波模拟器距离模拟电路的设计及实现方案。该距离模拟电路具有调整动态范围大、精度高等特点。调试表明,该电路能够满足精密测试引信截止距离的要求。     

一种新颖高效的气体发生器

针对启普发生器使用过程中存在液体使用量大、反应溶液利用效率低、安全性差等问题,研制了一种新型的气体发生器。该装置由储液杯、流量调节器、排气管和反应容器组成。利用流量调节器将反应液滴加到固体药品上,固-液反应充分,排出的废液基本不含反应试剂,大大减少了液体药品的用量。实验结果表明,该新型制气装置具有液体试剂用量少、利用效率高、安全性能优良、操作方便,同时兼具随开随用等特点,可有效地应用于化学实验教学中。     

汽轮发电机定子结构的动力分析和模型试验研究

本文用有限元方法分析了两种常见汽轮发电机定子结构模型的动力特性,建立了固有特性对集中质量、连接刚度及基础刚度的灵敏度分析方法,对这两种结构模型进行了振动实验研究,实验结果与有限元分析结果吻合较好.从避开共振的角度出发,对两种结构作了评价.本文的研究方法及实验结果对汽轮发电机结构设计、减振、隔振和降噪等方面的工作具有一定的参考价值和实际工程意义.     

一种用于UWB系统的高斯脉冲发生器

提出了一种新型的用于超宽带系统的高斯脉冲发生器.该脉冲发生器采用阶跃恢复二极管,结构简单,且易于实现.电路中加入一个放大器,以便阻止反射波对阶跃恢复二极管的影响,较好地抑制了脉冲尾部的波动,并使用共面波导实现.该极窄高斯脉冲的脉宽仅为300ps,且有很好的对称性.     

用于列ADC电路的斜坡发生器设计

设计了一种用于CMOS图像传感器列级模数转换器(Analog-to-Digital Converter,ADC)电路的10位斜坡发生器.详细介绍了电路的整体结构、工作模式以及仿真结果.在电路中采用了两级转换的方式,并设计了电阻阵列式多路斜坡发生器.在Cadence设计平台下,对模拟电路进行了设计、仿真和版图设计.采用0.5μm双层多晶三层金属(Double Poly Triple Metal,DPTM) CMOS工艺对电路进行了制作.仿真结果表明,该设计基本满足相关要求.