电位滴定法标定余氯标准物质

应用自动电位滴定仪,建立了电位滴定法标定余氯标准物质的方法。根据电位滴定法的基本原理分析该法的影响因素,分别从滴定液预加体积、加液步长以及加水量等滴定条件进行方法优化,确定电位滴定法的滴定参数。采用建立的方法对余氯标准物质进行标定,验证方法的精密度和准确度。结果表明该法的相对标准偏差为0.09%,与手工滴定法标定值的相对误差为-0.08%。证明建立的电位滴定法能够准确标定余氯标准物质,同时操作简便、重复性好并且具有可行性和实用性。     

直流电车杂散电流对城市燃气管道电腐蚀的影响规律研究

为得到轨道与埋地管道并行情况下杂散电流对管道电腐蚀的影响规律,建立了基于电路原理和电力系统接地极理论的双边供电直流电车杂散电流对管地电位干扰模型,并求得了轨道电位和管地电位的分布变化函数以及杂散电流泄漏量分布函数。采用MATLAB进行了数值模拟,得到了杂散电流泄露规律及其对管地电位干扰规律,并对管道防腐蚀层单破损点、双破损点情况下管道的电腐蚀规律进行了分析。结果表明:轨道杂散电流泄露量与轨道电位大小成正比,降低轨道电阻可减小杂散电流泄露量。防腐蚀层单破损点不易产生腐蚀,双破损点导致局部腐蚀较严重,且变电站附近的点腐蚀严重。因此,应重点监测保护变电站处下方管道以减少产生多破损点的概率。     

受污染金光菊的植物电信号研究

选取敏感植物金光菊(Rudbeckia hirta L.)作为研究对象,首先采集其在正常生长情况下和二氧化硫污染情况下的电波信号;然后运用时域、频域等方法对电波信号进行分析,比较正常和受污染植物的电位信号.通过分析植物在受污染条件下电信号的特征电位,确定污染及不同污染程度与其特征电位的关系,为植物监测环境奠定了一定的理论基础.结果表明,利用植物电波信号监测环境以及根据反馈的信息来改善环境和植物生长状况是可行的.     

自动电位滴定法与手动滴定法测定酱油中总酸和氨基酸态氮的比较

探讨用自动电位滴定法测定酱油中总酸和氨基酸态氨的含量.方法:用798MPTTitrino自动电位滴定仪测定酱油中总酸、氨基酸态氮含量.结果测定5份酱油中总酸、氨基酸态氮的含量与按照国标方法(GB/T5009.39-2003)中人工操作滴定法所测得的结果作比较,差异无显著性(统计学处理所得P＞0.05).结论:自动电位滴定仪法具有自动化程度高,操作简便、测定快速、准确、重复性好等优点.使用自动电位滴定法测定酱油中的总酸、氨基酸态氮具有操作简便、测定快速、准确等优点,在经济条件允许的情况下,是值得推广应用的分析方法.     

监督抽查

飞利浦耳机等4款产品有毒物质含量超标日前,北京有关部门公示流通领域电子产品有毒有害物质项目质量监测结果,飞利浦耳机、夏新DVD等4款产品样品中,各有材料有毒有害物质含量超标,被责令退出北京市场。监测发现,标称飞利浦(中国)投资有限公司生产的"PHILIPS"多媒体耳机(SHM1500/93),样品中有2种元件材料的有毒有害物质含量超过标准要求限值,且产品说明书中的有毒有害物质或元素声明与检测结果不相符,被判定为不合格。标称深圳市海力士科技有限公司生产的"AMOI夏     

COD在线自动监测仪测定方法对比及发展趋势

<正>随着科技的进步,更加便捷的自动化仪器越来越多地出现在环境监测领域。为了准确监测自然水体和污染源排放中有机污染物的变化,及时掌握主要流域重点断面水体的水质状况,预报重大或流域性水质污染事故,解决跨行政区域的水污染纠纷,监督污染源排放总量及排放达标情况等,需要使用水质在线自动监测仪。近年来,在水质监测方面出现了COD、BOD、TOC等在线自动监测仪。自动在线监测仪与传统的实验室仪器相比,不仅能实时监测,使监测者及时地得到连续的监测数据,而且节省了大量的人力,方便了环保部门对排污单位的监督和管理。就以测定COD为例,对不同种类的COD在线自动监测仪进行分析对比。     

基于鱼类活动生物电信号高精度计测的水质监测系统设计

鱼类水质监测法是目前水质生物监测法的一个重要方向。针对鱼类活动生物电信号强度弱、易受噪声干扰、以及鱼类水质监测传感器缺乏有效判定依据等难题，通过对观测电极采集到的鱼类活动电信号进行滤波增幅处理，再通过MSP430进行采集、转换，并在基于Labview程序设计的上位机中分别计算鱼类各种活动电位信号(呼吸运动和游泳运动)的功率谱密度，实现鱼类活动电信号的频域分析。然后，结合各类运动功率占比变化超过阈值与否这一全新判据，完成预警判断。最后，通过实验证明所开发系统的有效性。     

酚系物标准物质在水质监测中的作用

环境污染日益受到人类的重视 ,其中 ,与人们生活息息相关的自然水体的污染已引起有关部门的高度重视。在众多水污染物中酚系物是不容忽视的一类有毒有害的有机物质。酚类为原生质毒 ,属高毒物质。人体摄入一定量时 ,可出现急性中毒症状 ,长期饮用被酚类污染的水 ,会引起头昏、出疹、瘙痒、贫血和各种神经系统症状。为了满足人们高质量生活水平的要求 ,这类物质的检测已被环境监测及卫生防疫部门列为常规监测项目。准确、有效地监测这类有毒有害物质对水质的控制具有重要的意义。酚系物（苯酚、间甲酚、４-硝基酚、２ ,４-二氯酚、２,４ ,６-…     

烟气在线监测系统及思考

固定污染源排放的烟气会对环境造成污染,对其进行科学监测至关重要。本文介绍了现有的烟气在线监测系统,包括空气质量自动监测系统、烟气排放连续监测系统、差分光学吸收光谱法在线连续监测系统、物联网下无线传感器网络技术在线监测系统等,介绍了每个系统的组成、技术特点、监测方法、实际应用和发展方向,并从量值溯源和远程校准两个方面对烟气在线监测系统与计量系统的关系进行了阐述。     

基于DCPD的CT试样裂纹扩展数值模拟标定方法

为保证核电结构裂纹扩展监测结果的准确性,建立有效的标定方法至关重要。该文根据直流电位降(DCPD)法的原理和有限元分析软件建立电位场模型,直观、定量地获得电位场变化数据,分析紧凑拉伸(CT)试样在不同裂纹长度下的电位降,并从监测环节考虑多种因素对标定曲线的影响,最后结合裂纹监测平台进行实验验证。结果表明,裂纹主电位接线点的位置、不同材料和几何尺寸对标定曲线产生微伏级的影响,仿真与实验数据分析结果的最大误差为4.9%。该标定曲线具有一定的可行性,可为后续动态裂纹扩展监测实验及验证工作提供参考。     

基于视频算法的鱼类运动跟踪研究

针对利用鱼类行为监测进行水体环境保护的问题,本文提出了基于视频的鱼类运动跟踪研究,通过对鱼类运动视频进行分割、跟踪,获得鱼类运动的轨迹和速度,为鱼类参与环境污染研究奠定了理论基础(通过对比不同污染环境中鱼类运动的一些参数,进行水体环境污染程度的定量分析).该算法采用标记多尺度分水岭方法进行鱼类运动分割,然后通过改进的加权Hausdorff距离对鱼类运动视频进行跟踪,最后为了容纳鱼类在运动过程中形状的变化,在多值图像中引入欧几里德范数作为约束务件来完成跟踪模型的更新.实验结果表明,本文算法呈稳定跟踪状态,在连续100帧的跟踪过程中没有出现超过1个像素的位置差,跟踪速度差值也未超过0.12个像素,能够快速、精确分割和跟踪鱼类运动目标.     

Electrochemical development of hydrogen silsesquioxane by applying an electrical potential

We present a new method for developing hydrogen silsesquioxane (HSQ) by using electrical potentials and deionized water. Nested-L test structures with a pitch as small as 9 nm were developed using this electrochemical technique in saline solution without adding hydroxyl ions. Furthermore, we showed that high-resolution structures can be electrochemically developed in deionized water alone. Electrochemical development is controlled by the applied voltage and may overcome several of the limitations discussed for alkaline developers, such as poor hydroxyl anion diffusion and charge repulsion effects in small trenches.     

活性炭在东南区水厂水质处理中的应用

我市东南区水厂水源的污染比较严重,尤其在沽水季节,甚至影响到了出厂水的水质,其中有机物的污染占了相当大的比例,采用活性炭处理工艺后,水质各项指标得到改善,取得了一定的效果。     

电子离子净水技术

介绍了电去离子（EDI）净水技术，讨论了笔者建立的反应叠加实用分析方法，并用它分析说明低含盐量时和高含盐量时应用EDI净水的工况。     

罗非鱼片冻结新工艺的试验研究

本文介绍了一种罗非鱼冻结的新工艺，即利用低温氯化钙溶液对鱼片进行冻结的新工艺。新工艺不仅实现了连续冻结加工，并且因采取蓄冷方式而减小制冷机组的容量，还由于可选择用电低谷的时间段工作而节省电费。通过一年多的探索和生产实践证明，新冻结工艺可行，并具有良好的可靠性和经济性。     

A new linearly constrained minimum variance beamformer for reconstructing EEG sparse sources

Brain source imaging based on EEG aims to reconstruct the neural activities producing the scalp potentials. This includes solving the forward and inverse problems. The aim of the inverse problem is to estimate the activity of the brain sources based on the measured data and leadfield matrix computed in the forward step. Spatial filtering, also known as beamforming, is an inverse method that reconstructs the time course of the source at a particular location by weighting and linearly combining the sensor data. In this paper, we considered a temporal assumption related to the time course of the source, namely sparsity, in the Linearly Constrained Minimum Variance (LCMV) beamformer. This assumption sounds reasonable since not all brain sources are active all the time such as epileptic spikes and also some experimental protocols such as electrical stimulations of a peripheral nerve can be sparse in time. Developing the sparse beamformer is done by incorporating L1-norm regularization of the beamformer output in the relevant cost function while obtaining the filter weights. We called this new beamformer SParse LCMV (SP-LCMV). We compared the performance of the SP-LCMV with that of LCMV for both superficial and deep sources with different amplitudes using synthetic EEG signals. Also, we compared them in localization and reconstruction of sources underlying electric median nerve stimulation. Results show that the proposed sparse beamformer can enhance reconstruction of sparse sources especially in the case of sources with high amplitude spikes.     

Dynamic behavior of a crack in a functionally graded piezoelectric strip bonded to two dissimilar half piezoelectric material planes

Summary. The dynamic behavior of a crack in a functionally graded piezoelectric material (FGPM) strip bonded to two half dissimilar piezoelectric material planes subjected to combined harmonic anti-plane shear wave and in-plane electrical loading was studied under the limited permeable and permeable electric boundary conditions. It was assumed that the elastic stiffness, piezoelectric constant and dielectric permittivity of the functionally graded piezoelectric layer vary continuously along the thickness of the strip. By using the Fourier transform, the problem can be solved with a set of dual integral equations in which the unknown variables are the jumps of the displacements and the electric potentials across the crack surfaces. In solving the dual integral equations, the jumps of the displacements and the electric potentials across the crack surfaces were expanded in a series of Jacobi polynomials. Numerical results illustrate the effects of the gradient parameter of FGPM, electric loading, wave number, thickness of FGPM strip and electric boundary conditions on the dynamic stress intensity factors (SIFs).     

自适应空间有源消声最佳消声效果的实现

本文针对一个自适应有源消声控制系统以及一个以点声源为次级源的声系统，就如何实现空间最佳消声效果问题进行了讨论，给出了误差传声器的个数及空间位置与空间消声效果之间的关系，提出误差传声器应放置在实现消声后声压的极小方向上。所得结论在实验中得到了证实。     

Design of a plate-type evaporator for heat pumpsConception d'un évaporateur à plaques pour pompes à chaleur

Use of particularly cold and/or polluted water as a heat source for heat pumps makes special demands on evaporator design. The plate-type evaporator is probably the most suitable design. It can be cleaned easily and ice formation does not cause any damage to it. High plate efficiency is attained by using narrow, vertical refrigerant flow channels. On the water side falling film flow is recommended. Under such conditions, evaporator k-values of up to approximately 1400 W m^?2 K^?1 and 1200 W m^?2 are reached in laboratory tests, using refrigerant R 22 and R 12 respectively. Experiments have shown that water of 2°C and even lower temperatures may be used. This opens for use significant heat sources, which probably could not be exploited economically with other evaporator types.     

Modeling and optimization of high-frequency ultrasound transducers

Obtaining an accurate transducer model for a high-frequency transducer can be troublesome using traditional models, such as the KLM model, since it is often difficult to measure precisely the piezoelectric, dielectric, and mechanical properties of the transducer. This paper describes an alternative method of modeling transducers using network theory. The network theory model for a transducer is determined from a measurement of the transducer impedance in water and the pulse-echo response of the system for a given electrical source and load. A discussion of how this model can be used to optimize the design of an electrical matching circuit is given. This method is illustrated by designing a two-element transmission line matching circuit for a miniature 53 MHz transducer. Excellent agreement between the network model prediction and the experimental response is obtained