基于相关法的差分式科氏流量计幅值检测算法

为提高差分式科氏流量计幅值检测的精度,提出了基于相关法的幅值检测算法。首先构造两路与采样信号同频的参考信号,然后分别与采样信号进行互相关得到互相关信号,估计出采样信号的初相位,最后检测出采样信号的幅值。理论分析表明:该方法不受信号非整周期采样的影响。仿真实验结果表明:该方法提高了检测精度,在信噪比45d B时,测量相对误差低于0.25%。     

波动率风险溢价——基于VIX的实证

波动率风险溢价是金融学文献关注的核心问题之一. 基于非仿射GARCH扩散模型,推导相应的VIX公式,继而采用S&P500与VIX 指数联合数据,给出模型客观与风险中性参数基于有效重要性抽样（EIS）的联合极大似然（ML）估计. 进一步利用粒子滤波 方法给出隐波动率的估计,推断VIX隐含的波动率风险溢价. 蒙特卡罗模拟实验表明,提出的估计方法是有效的. 采用实 际数据进行的实证研究表明,波动率风险被定价,且波动率风险溢价为负,隐含市场投资者整体表现为风险厌恶.     

基于低帧频CCD的快速反射镜系统控制(英文)

低频采样和延迟对光电成像跟踪系统会带来严重的相位滞后,极大地限制了系统闭环带宽和跟踪精度的提高.零极点对消法虽可以抑制对象谐振而扩大系统带宽,但必须依赖精确的数学模型和较高的采样频率.分析了复数零点PID控制器在低频采样的FSM控制系统中的应用,可以获得较好的闭环性能而且可以避免零极点对消法无法单独应用于低频采样的跟踪系统的问题.采用200 Hz帧频的CCD对此方法进行了实验验证,实验结果证明满足设计要求.     

心电信号数据采集系统的设计

介绍了心功能自动检测系统的关键部件———心电数据采集系统和心电放大器的设计原理以及数据采样卡的软硬件设计 .分析了体表心电信号的特点     

柏大蚜空间分布型的研究及其应用

在抽样调查的基础上 ,计算出柏大蚜 (CinaratuiafulinaDel.Guercio)的 4种聚集度指标 ,从而确定了柏大蚜在空间为聚集型分布 .同时讨论了柏大蚜的空间分布型在序贯取样中的应用 ,也对其在不同密度下的最适抽样数进行了研究 ,为以后在试验设计中的取样技术提供理论依据 .     

(Pareto-U)模型下二行动线性决策问题的EVSI

讨论了均匀分布U(0,θ)共轭于Pareto分布模型下的二行动线性决策问题的抽样信息期望值(EVSI)的计算公式.     

家鸽顶盖脑片中Ⅱ g—j亚层神经元对乙酰胆碱的反应

在家鸽的离体顶盖脑片上，用玻璃微电极记录了顶盖Ⅱg-j亚层神经元对灌流乙酰胆碱所产生的反应，结果如下：在顶盖IIg-j亚层记录到66个神经元的自发放电，根据其放电特征，将它们分为3种形式：单个放电，丛状放电和连续放电，其中的46个神经元单位中有34个（34／46）对 酰胆碱产生自发放电增频反应；4个单位（4／46）的自发放电被乙酰胆碱抑制；8个单位（8／46）对乙酰胆碱无反应，在20个对乙酰胆碱产生增频反应的神经元单位中，有14个单位（14／20）的自发放电被阿托品所抑制，乙酰胆碱和阿托品的作用还具有可逆性的重复性，以上结果提示：在家鸽顶盖IIg-j亚层中可能有胆碱能纤维到达并存在乙酰胆碱敏感神经元。     

Cerebral ischemia revisited: New insights as revealed using in vitro brain slice preparations

Summary The elucidation of the pathophysiological mechanisms of cerebral ischemia/hypoxia dictates the use of experimental models which mimic this disabling brain condition. In vivo experimental models have been available for many decades and are responsible for the bulk of, though incomplete, knowledge we have about these mechanisms. Since study in isolation of each postulated mechanism is impossible in vivo, the need for an in vitro experimental model has intensified in recent years. Consequently, rat and guinea pig hippocampal slice preparations have emerged as the models of choice. This review attempts to highlight some of the results obtained using brain slices in the study of cerebral ischemia/hypoxia and compare them to those obtained in vivo. Both the biochemical and the physiological correlates of energy metabolism, ion homeostasis, neurotransmission and neuromodulation of this brain condition are reviewed. The agreements, and especially the disagreements, between the in vivo and in vitro findings are emphasized. Details are given of the possible roles of both lactic acid, Ca²⁺ and excitotoxins in the neuronal damage inflicted by cerebral ischemia/hypoxia. Recent attempts to protect brain slices against experimental cerebral ischemic/hypoxic damage are also reviewed here briefly.     

Optimum linear array of an optical aperture synthesis telescope

Measuring out successively the degree of coherence of the source produced by any couple of the small apertures via rotating an array composed of the small aperture telescopes, and synthesizing them into the (u, v) coverage of the source, the brightness distribution of the source can be obtained by the inverse Fourier transform of the degree of coherence with much higher resolution than from a single telescope. This article discusses the arrangements of the small apertures in the linear array, and found a method to decide the quality of the arrangements. the judgment factor ε is introduced to calculate the arrangements in quantity. There are 1.5×10¹¹ possibilities for 11 apertures. Therefore, the computer procedures are programmed to select the optimum arrangements. The effect of the simulation of the aperture synthesis is given for the linear array. The simulation method can also be used in the nonlinear arrays.     

电力系统安全经济运行的序贯概率仿真

电力系统的安全经济运行对国民经济意义重大。本文讨论了电力系统设备的概率模型,采用序贯仿真算法,按时间顺序采用蒙特卡罗抽样方法模拟设备的随机故障和电力系统的运行状态,采用线性规划优化算法对运行方式进行优化调度,以减少用户停电损失。文中建立了以停电指标为基础的安全指标和以发电成本表示的系统经济指标,并给出了IEEE-14节点系统的仿真结果。作为辅助决策工具,该算法的实现有利于量化评估电力系统的安全经济性能,具有一定的工程应用价值。