铅离子电极测定天然水、废水和空气中的铅

铅电极已用于蓄电池含铅废水和尿铅的测定,并有关于含铅工业废水及硫酸硝酸中硫酸浓度的连续自动监测的报导。中国计量科学研究院还应用PbTe/Ag_2S陶瓷膜铅电极测定天然水、废水中铅取得了较好的效果。我们从1978到至1980年多次运用GSP—76—01型P~(p~b)电极在0.5MKNO_3介质中用标准曲线法、标准加入法、离子活度计标准定位法作了天然水、废水和空气中的铅的测定,得到了与比色法基本一致的分析结果。     

基于BP神经网络的云相态检测方法研究

利用MODIS中5个光谱波段上不同云相态的特性,提出了一种基于BP神经网络的云相态检测方法。首先,分析了所选波段上不同云相态的特性,利用5个波段上光谱图像的反射率、亮温值和亮温差值构成4组特征数据作为输入层,隐层和输出层分别采用优化的传输函数。然后,利用3层前馈型BP神经网络对所选波段MODIS数据进行了云相态检测。最后,将两组测试数据用该BP神经网络算法进行云相态检测的结果与相应MOD06云相态数据进行了对比分析,结果表明该方法能很好地识别云相态,检测平均准确率达到86.11%,计算结果与标准结果平均相关性达到0.874的高度相关,且无需在计算前进行复杂的云和晴空分离处理。     

目标约束遗传算法用于铜相态分析的研究

根据铜矿物各相的浸取特性，利用铜各相态稳定的浸取率常数建立数学模型，用目标约束遗传算法（GA）对一次性浸取测得的浸取总量进行计算，求得铜各相态的含量。该方法简便快速，缩短了传统相态分析的流程，避免了串相问题，为相态分析提出了一种新方法，相对标准偏差（％）为：自由氧化铜相1.46，结合氧化铜相17.59，次生硫化铜相1.86,次生硫化铜相1.86，原生硫化铜相2.73，总铜0.803。     

模糊逻辑法在3 mm云雷达反演云中水凝物粒子相态中的应用

利用模糊逻辑算法,结合大气辐射测量项目（ARM）中国寿县移动观测站3 mm云雷达（WACR）资料,进行了云中水凝物相态垂直分布的反演研究。根据Shupe总结得到的不同相态水凝物粒子对应的毫米波雷达反射率、Doppler平均速度、谱宽以及温度的阈值,建立了基本形式为不对称的T型函数的模糊逻辑识别的隶属函数,并根据不同相态粒子的散射特性和几何形状等增加了关于退偏振比的隶属函数。然后根据建立的隶属函数利用寿县站的3 mm云雷达资料进行水凝物相态垂直分布的反演研究。结果表明：利用模糊逻辑法处理偏振3 mm雷达测量到的参量,可以识别云中粒子相态,反映云的相态结构,识别结果基本合理,但是T型函数系数的选取还需要进一步研究。     

基于双偏振天气雷达的水凝物相态识别技术研究进展

水凝物相态识别（Hydrometeor Classification Algorithm,HCA）是从微物理角度分析天气特征的一个重要研究方向,研究水凝物粒子的分类,对于冰雹、降雨、降雪的观测均有重大意义。分析并总结了目前模糊逻辑水汽分类算法（Fuzzy logic Hydrometeor Classification,FHC）的优势,但是其局限性在于FHC较大地依赖于散射模拟,对冰相粒子相态识别的结果不确定。此外,目前也缺少有效的相态识别验证方法,这进一步限制了雷达双极化特征的应用。因此,发展其他聚类算法进行相态识别并建立分类标准体系是未来主要研究方向。     

关于铅离子选择电极测定非响应金属离子方法的探讨

铅离子选择电极除直接用于测定铅外,还广泛地被用作指示电极电位滴定法测定硫酸根、草酸根、磷酸根等能与铅离子形成难溶盐的阴离子。关于用其间接测定其它金属离子,文献中未曾见到。本文将阐述用铅离子选择电极作指示电极测定锌镁钙等金属离子的方法。一、仪器和试剂pHS—2型酸度计(上海第二分析仪器厂)磁力搅拌器(上海南汇电讯器材厂)217型双接界饱和甘汞电极,外套管充饱和硝酸钾溶液。(江苏电分析仪器厂)铅离子选择电极:自制 Ag_2S—PbS 均相膜全固态铅离子选择电极。     

铅离子电极测定金属锌中微量铅

铅离子选择电极法测定微量铅已用于酒类、废水、药物等方面,金属锌中微量铅的电极测定法未见报导。本文采用于振安等提出的(CH_2)6N_4—HCHO—Triene—KNO_3体系,以消除Cu~(2+)、Fe_3~+、Hg~(1+)、Ag~+等的干扰,该文中指出Zn大于Pb100倍将产生干扰,我们用标准加入法得到消除。实验证实电极法测定结果与光度法一致。     

三氯杀螨醇中间产品—对氯苯磺酸中H2SO4含量的测定

用铅离子选择电极作指示电极电位滴定法测定硫酸根的方法已有不少报导,但多用于水质分析方面或无机体系中硫酸根的测定,我们应用该法对农药制备工艺中间产物里的硫酸根(SO_4~(2-))测定条件进行了选择和研究,为了便于对产品质量的控制,生产中常需对三氯杀螨醇的中间产品——对氯苯磺酸中的硫酸含量进行测定,但目前国家并无统一的分析标准,工厂中常用的是 Bacl_2—K_2cro_4滴定法,这种方法是外指示剂法,不仅手续繁索而且精度也不够。我们的研究结果表明,采用铅离子选择电极电位滴定法测定该体系的硫酸根,不仅能满足工艺中间控制的要求,而且操作简单,省时,省力,费用也低,扩大     

土壤中铅的来源及生物有效性

土壤中铅有自然来源和人为来源。植物对铅的吸收和积累,决定于环境中铅的浓度、土壤条件、植物种类、叶片大小和形状等。饮用水中的铅主要来自河流、岩石、土壤和大气沉降。在生物圈循环过程中,铅污染通过呼吸、饮用水、食物等途径到达食物链的终端,最终使人体受到铅的危害。土壤铅全量与作物产量及铅吸收量的相关性要低于土壤有效铅。影响土壤铅的植物有效性的因素包括土壤铅全量、土壤理化性质、土壤微生物、高等植物等。目前,评价土壤中金属植物有效性的方法主要有:化学提取法、植物吸收试验、微生物和酶活性试验及同位素法。     

离子选择电极法测定食醋中的微量铅

前言用铅离子选择电极测定食品中的微量铅的研究,国内外报导很少。由于食品中成份较复杂,干扰物很多而铅离子选择电极的灵敏度、选择性较差,所以一般实际测定食品中微量铅的方法有原子吸收法、双硫腙比色法。原子吸收法仪器昂贵,食品生产厂家无力购置。而双硫腙比色法操作步骤繁琐,分析时间长,使用试剂污染环境。此两种方法都不便于生产中随时检查、监测。本文主要研究了食用醋中的微量铅的测定。在食醋中主要含有大量的 Ac~-离子及各种有机物质,对铅离子选择电极的测定有严重干扰。通过实验考     

基于参数样条插值的同坡曲面构造方法

传统的同坡曲面构造方法都是在导线方程为已知的前提下进行的。然而在实际工程中,导线方程往往是很难得到的,只能通过测量得知导线通过一列数据点。针对这一问题,给出了一种实际工程中同坡曲面的构造方法,该法首先根据测量数据点,利用三次参数样条曲线插值方法构造出同坡曲面的导线方程,然后再从同坡曲面的形成原理入手建立其参数方程,最后通过实例表明该方法是可行有效的。     

Netnography as a Method of Lead User Identification

Lead users are rare subjects, which are difficult to detect. In theory and practice, mass screening is the main method of lead user identification. It is a standardized, quantitative approach, based on screening a large number of potentially relevant users. Shortcomings of screening are low sample efficiency, high search costs and the reliance on the self‐assessment of respondents. Thus, the elaboration of lead user identification methods is still a major challenge to researchers in the field. In this paper, we propose netnography as a new method of lead user identification. Netnography, made up of internet and ethnography, is an approach to analyse online communities systematically. The empirical results of our explorative study of the online community utopia show that 9 out of 40 of the most active online community members possess lead user attributes (22.5 per cent). Hence, we may conclude that netnography is a viable method of lead user identification, which relies on external assessments instead of self‐assessments and is probably less costly than mass screening.     

一种基于DCT Cycle Spinning的图像压缩方法

综合利用DCT变换和Cycle Spinning,提出一种新的图像压缩方法。由于图像的DCT压缩是分块完成的,且DCT变换缺乏平移不变性,直接应用DCT变换对图像进行压缩会使压缩重构图像产生块效应和伪吉布斯现象,导致图像失真。引入Cycle Spinning算法能有效地消除图像DCT压缩过程中产生的失真。实验结果表明,与一般图像DCT压缩方法相比,该方法明显改善图像视觉效果,显著提高图像的PSNR值。     

A framework for end-to-end deterministic-delay service provisioning in multiservice packet networks

The problem of providing end-to-end delay guarantees for deterministic-delay services in multiservice packet networks is addressed through a combination of dynamic resource reservation and routing. Our model is based on using rate-controlled earliest-deadline-first (RC-EDF) for providing hard bounds on end-to-end delays. With RC-EDF, a certain delay bound has to be allocated for a connection at each node in the selected path. The most commonly used resource reservation policy is uniform allocation which is based on dividing the end-to-end delay bound equally among the nodes in the selected path. This simple allocation policy could lead to nonuniform resource loading and subsequently lead to high blocking rates. Moreover, the most commonly used routing method is shortest-path first routing which is known to lead to network hotspots. We propose a set of dynamic nonuniform resource reservation policies and dynamic routing methods. One of the routing methods is the well-known widest-shortest path method and the other is a dynamic routing method that adaptively adjusts link costs and uses a similar algorithm to shortest-path routing (e.g., Dijkstra's algorithm). We show that for both uniform and nonuniform traffic loading of some example network topologies that the combination of the proposed resource reservation policies and dynamic routing can lead to significant reduction in the connection blocking ratio in all loading conditions except for excessively high loads.     

基于动态批量和提前期的MRP研究

MRP是ERP的关键。论文分析了基于固定批量和提前期来确定计划数量和计划时间的传统MRP算法存在的问题,提出了利用日产量对批量和提前期进行动态调整的方法,并给出了相应的MRP算法。     

位置伺服系统的学习控制研究

本文通过对位置伺服系统的学习控制的实验研究,提出系统滞后是学习控制过程发散的 主要原因.针对这一问题,文中提出了三种解决办法,即给定超前法、给定滤波法和给定超前 滤波法,并在实验中取得了满意的效果.     

分数线性相位超前迭代学习控制

线性相位超前迭代学习控制的超前拍数需要取整,不利于控制系统的性能达到最优.对此提出分数线性相位超前迭代学习控制.对系统的收敛条件进行频域分析,得到超前拍数,学习增益和可学习带宽的范围.通过调节超前拍数来提高系统的可学习带宽,以达到更高的跟踪精度.给出了分数线性相位超前的具体实现方法,并在此基础上对整数与分数相位超前的补偿效果进行比较.以机械臂为被控对象的仿真结果表明了分数线性相位超前更能提高系统的可学习带宽及跟踪精度.     

Accuracy of two dipolar inverse algorithms applying reciprocity for forward calculation.

Two inverse algorithms were applied for solving the EEG inverse problem assuming a single dipole as a source model. For increasing the efficiency of the forward computations the lead field approach based on the reciprocity theorem was applied. This method provides a procedure to calculate the computationally heavy forward problem by a single solution for each EEG lead. A realistically shaped volume conductor model with five major tissue compartments was employed to obtain the lead fields of the standard 10-20 EEG electrode system and the scalp potentials generated by simulated dipole sources. A least-squares method and a probability-based method were compared in their performance to reproduce the dipole source based on the reciprocal forward solution. The dipole localization errors were 0 to 9 mm and 2 to 22 mm without and with added noise in the simulated data, respectively. The two different inverse algorithms operated mainly very similarly. The lead field method appeared applicable for the solution of the inverse problem and especially useful when a number of sources, e.g., multiple EEG time instances, must be solved.     

Nonlinear platoon control of Arduino cars with range-limited sensors

This paper investigates the problem of platoon control with sensor range limitation. A nonlinear vehicular platoon model is established, in which the sensing range constraint described by a piecewise nonlinear function is involved. Then a robust nonlinear control design method is proposed based on a disturbance observer and the backstepping technique. The results are obtained in the context of both individual vehicle stability and platoon string stability analysis, which can lead to substantially enhanced platoon control performance with a guaranteed level of attenuation of the disturbance caused by lead vehicle acceleration and wind gust. The effectiveness of the method has been shown by numerical simulations and experiments carried out with Arduino cars.     

基于紧支集双正交小波的芯片焊点定位技术研究

芯片封装是保护芯片和增强芯片电热性能的重要工艺,在芯片粘贴在引线框架的贴片基板上后,用金属引线将芯片焊点与引线框架的管脚连接起来实现芯片功能。为了提高芯片引线键合的精度,确保键合机的焊头能够实现准确定位,采用基于紧支集双正交小波的多分辨率分析方法实现芯片和贴片基板边缘的快速检测和特征匹配,实现芯片和引线框架焊点的快速定位。这种方法能够实现芯片图像边缘特征的准确提取、识别和特征匹配。采用紧支集双正交小波进行芯片焊点和引线框架定位时,简化了算法的复杂度,提高了芯片引线框架焊点位置的检测效率和定位精度。