EIS检测电极屏蔽地环宽度对成像结果的影响

目的：评估电阻抗乳腺扫描（EIS）技术中检测电极阵列周围屏蔽地环大小对系统检测性能的影响,并针对64电极阵列提出合适的地环宽度.方法：在64电极的物理模型中模拟人体乳腺组织分布,采用相同电极阵列、不同屏蔽地环宽度的检测电极,分别检测均匀背景溶液、同一体积和深度的琼脂目标体,对比测量结果.人为使用绝缘材料遮盖检测电极屏蔽地环,测量30例女性志愿者,观察地环屏蔽前后的数值变化.结果：屏蔽地环宽度越小,电场边缘效应越明显,测量数据的离散性呈以下趋势：0 mm〉2 mm〉3 mm〉5 mm〉7mm.在临床检查中,屏蔽地环的不良接触同样影响EIS成像质量.结论：电极屏蔽地环宽度大小对于EIS成像中检测性能的影响至关重要,介于5-7 mm之间的屏蔽地环宽度对于64电极阵列较为合适.

地环类本科大一新生专业认知度及其教学建议

以安徽理工大学地质、环境和水文专业大一新生为调查对象,摸清该年级段对专业的认知程度,提出针对性的教学响应措施。安徽理工大学大一新生在入学前专业认知起点和意愿性低,入学半年教育后有所提升,整体认知处于中等水平。建议整合资源,拓宽"第一课",多形式结合,进一步完善专业认知教育体系。

基于CDIO理念与模块教学法的土地资源学教学改革探讨——以广州大学地环专业为例

土地资源学是广州大学自然地理与资源环境（国土资源方向）专业连接地理学、资源科学专业理论素养与国土管理业务知识体系的桥梁。目前,该专业国土资源相关课程的教学模式对自然地理领域课程依赖较强,无法凸显国土资源的应用导向。开展土地资源教学改革对明确专业定位、丰富专业建设经验意义重大。本文在土地资源学教学现状评价分析的基础上,引入CDIO理念与模块教学法,构建教学实践平台体系,将土地资源学教学内容整合为三大项目模块,并将二者耦合,创新性地提出＂做中学＂原则下土地资源学教学改革模式。

测地环的实时计算与交互选择

针对测地环在模型分割等应用中的实时性和交互易用性的要求,提出一种基于测地环与测地Morse-Smale鞍点之间的内在联系的快速测地环算法.首先利用快速前进法计算以曲面上给定点为源点的测地距离场;然后对于距离场中的每一个测地Morse-Smale鞍点,追踪出其对应的测地环;最后给出2种测地环交互的方式:借助人工交互选出与笔画轨迹最匹配的测地环,基于与模型凹陷特征的匹配程度自动选出最佳测地环.通过大量的实验结果,展示了该算法的有效性和有用性.

Role of outdoor trees on pedestrian wind and thermal conditions around a pre-education building for sustainable energy management

Finding sustainable energy resources is essential to face the increasing energy demand.Trees are an important part of ancient architecture but are becoming rare in urban areas.Trees can control and tune the pedestrian-level wind velocity and thermal condition.In this study,a numerical investigation is employed to assess the role of trees planted in the windward direction of the building complex on the thermal and pedestrian wind velocity conditions around/inside a pre-education building located in the center of the complex.Compared to the previous studies(which considered only outside buildings),this work considers the effects of trees on microclimate change both inside/outside buildings.Effects of different parameters including the leaf area density and number of trees,number of rows,far-field velocity magnitude,and thermal condition around the main building are assessed.The results show that the flow velocity in the spacing between the first-row buildings is reduced by 30%-40% when the one-row trees with 2 m height are planted 15 m farther than the buildings.Furthermore,two rows of trees are more effective in higher velocities and reduce the maximum velocity by about 50%.The investigation shows that trees also could reduce the temperature by about 1℃around the building.

一种用于辐射测量的电荷放大器设计

为解决辐射测量传感器输出电流难以准确采集的问题,该文设计并实现一种pA级电流放大器。首先对放大器的低频截止点、高频截止点、噪声特性和漂移等关键指标进行分析,基于电容积分原理设计一种用于pA级电流采集的电荷放大器,并从施加等电位屏蔽、提高绝缘性能、应用相位补偿和抑制噪声四个方面对放大器的性能进行优化,以确保其输出稳定可靠。最后,在多功能校准源Fluke 5720A、标准分压器和标准电阻箱辅助下,将该放大器的输出结果与Keithley 6514的测量结果进行比较,确定该放大器的测量准确度优于1%。并对该放大器的改进方向进行阐述。该放大器已被用于局部放电量在10 pC及其以下的校正脉冲发生器校准中,并取得良好的效果。

地球自转及其和地球物理现象的联系：Ⅰ日长变化

地球的自转运动（自转速率变化和地极运动）表征着地球的整体运动状况，以及地球各圈层地核，地幔，地壳，海洋和大气之间的相互作用过程，它们在维持总角动量守恒的条件下，形成了地球的动力学系统。在这个封闭的系统中，地球各圈层的力学过程和耦合作用以角动量交换的模式进行。因此，这个系统是一个典型的守恒系统，也是一个相互反馈的系统。本文回顾了近十年来的研究进展，分各个时间尺度讨论了日长变化及其地球物理激发原因，并评估未来十年内地球自转运动可能的研究方向及课题。

敏感设备抗干扰接地技术

通过接地干扰机理的分析,对敏感电子设备的接地抗干扰技术进行了研究,提出了一些有效的抑制电磁干扰的接地方法。这些方法在某工程中得到了实际应用,有效地提高了系统的抗干扰能力。

PLC控制系统接地抗干扰技术

PLC控制系统广泛应用于社会生产各个行业,其安全可靠程度直接影响生产过程,因此讨论其抗干扰技术就显得极其重要。在分析几种不同的接地抗干扰技术的性能基础上,针对PLC控制系统存在着各种干扰,如地环电流干扰、公共在线阻抗耦合干扰和导线间电、磁场耦合干扰等,充分利用接地技术,结合正确的屏蔽,在理论和实践上提出了问题的解决方案和措施,实现抑制和消除PLC控制系统中的大部分干扰问题,保证系统的安全运行,因此,近年来接地抗干扰技术越来越受到关注和重视。

弱电系统中接地干扰及其抑制措施

通过对弱电系统中单点接地与多点接地干扰形成机理的分析,提出不同信号频率条件下,单点接地与多点接地造成的干扰及其抑制措施。

地月系起源及其演化原理

本文在研究星系环演化的基础上 ,揭示了地月系起源及其演化原理。并从不同的方面进行了演绎阐述和归纳研究。

Evaluation on Coordination between Grassland Ecological Environment and Economic Development

Taking grassland resources in Nagqu District of Tibet as example,the evaluation index system of environment and economy coordination degree was set up according to coordination degree evaluation model,and environment economic system coordination degree of 11 counties in Nagqu District was analyzed by using coordination functions.

Fluorine Content in Soil and Groundwater of Songnen Plain in Northeast China

[Objective] This study aimed to investigate the fluorosis content in the groundwater of Songnen Plain and provide a theoretical basis for the prevention and control of endemic fluorosis in Songnen Plain. [Method] The relationship of drinking water type endemic fluorosis with the fluoride content in the soil and groundwater of Songnen Plain was analyzed. [Result] The endemic disease in this region is concentrated in the Song-Liao Plain and Hulunbuir Plateau on both sides of the Daxinganling Mountain. Severe and medium disease areas are distributed mainly in alluviallacustrine plains with dense depressions of lakes and marshes. The strata are commonly fine-grained loess and mucky soil. The groundwater is dominated by HCO3-Ca·Na and HCO3·Cl-Na·Ca types, with fluorine content of 1.80-16.00 mg/L, generally 4-6 mg/L. Light disease and non-disease areas are distributed in the alluvial-lacustrine plains with less or without depressions of lakes and marshes. The strata are mainly coarse-grained silty soil and sandy soil. The chemical types of ground water are Cl-Ca·Na and HCO 3 Cl-Na·Ca. The content of fluorine in ground water is commonly lower than 2 mg/L. [Conclusion] High fluorine groundwater formation is closely related to the geological environment.

Identification of Heterogeneity of Social and Economic Environment of Land Uses in China

The robust principal component analysis （RPCA） is a technique of multivariate statistics to assess the social and economic environment quality. This paper aims to explore a RPCA algorithm to analyze the spatial heterogeneity of social and economic environment of land uses （SEELU）. RPCA supplies one of the most efficient methods to derive the most important components or factors affecting the regional difference of the social and economic environment. According to the spatial distributions of the levels of SEELU,the total land resources of China were divided into eight zones numbered by Ⅰ to Ⅷ which spatially referred to the eight levels of SEELU.

Soil Environmental Quality Evaluation for Wasteland of Coalmine Tailing Polluted by Heavy Metals in Mingshan of Guangdong

ln order to appraise scientifical y the heavy metal contamination in waste-land of coalmine tailing in Mingshan of Guangdong, the 5 soil samples in wasteland of coalmine tailing were col ected in November 2010 to March 2011. The 7 heavy metals content in the contaminated soil was measured by atomic absorption spec-trophotometry. The results showed the pH of the wasteland soil ranged from 2.87 to 6.16, and the soil was relatively infertile. The soil was mainly pol uted by Cd and Mn. The Cd content in wasteland soil ranged from 0.759 mg/kg to 3.109 mg/kg with an average content of 2.052 mg/kg, which was much higher than the standard content. The Mn content ranged from 387.057 to 488.660 mg/kg with an average content of 421.215 mg/kg, which was much higher than the standard content. The Nemerow integrated pol ution indexes showed the sample 1, sample 4 and sample 5 were of heavy pol ution, and sample 2 and sample 3 were of moderate pol ution.

Influence of Soil Geochemistry to the Quality of Winter Jujube in Zhanhua

[Objective] The aim was to investigate the effects of soil geochemistry on the quality of winter jujube.[Method]Based on the data of ecological geochemical survey in lower Yellow River Basin,the relevance of the geochemistry environment in top soils and the quality of winter jujubes was analyzed.[Result]Cd,Ni and other heavy metals in the soil more obviously affected the nutrition of winter jujubes.[Conclusion]B,Mn,MgO,Cd,Zn,K2O and other elements in the root soil played an important role in the enrichment of Cr and Hg of winter jujube fruit.And the absorption of heavy metals in winter jujube root could be interfered by improving fertilization method,to reduce the enrichment of harmful elements in jujube fruit.

Research on Ecological Regionalization of Inland Lake Wetland of Bashang in Hebei Province

An ecological regionalization index system was established for Bashang inland lake wetland based on ecological and environmental factors,with landform,geomorphy,vegetation types and climate as primary indices,micro-landform,vegetation type,soil type,climate,ecosystem types,wetland features and human activities as secondary indices. Based on these index systems,the area was divided into three eco-environment regions and nine sub eco-environment regions. An eco-regional map of Bashang inland lake wetland was drawn by using GIS. The ecological characteristics,existing problems and control measures of each region were described. This study will supply guidance for the construction of local ecological environment and regulation of industrial structure,promoting sustainable development of Bashang inland lake wetland.

Comprehensive Evaluation of Environmental Effects from Land Change in Hotan Oasis,Xinjiang

[Objective] This study aimed to evaluate the environmental effects coming from land changes in Hotan oasis during 1980-2010. [Method] Based on the Driving Force-State-Response model, expert weight method and entropy method were used to determine weight, and then the composite indexes of environmental effects （CIE for short） were calculated. [Result] During the period from 1980 to 2010, CIE had presented a rising trend whether expert weight method or entropy method in the study area, while the CIE presents downtrend basically in lower reaches. [Conclu- sion] It was the arable land expansion in middle reaches that led to serious land degradation in lower reaches, and may endanger ecosystem safety in Hotan River green corridor. Therefore, it is suggested that the agricultural land use should be restructured, such as reducing the sown areas of some crops with large amount of water consumption. Meanwhile, the effective measures should be taken to distribute water resources and utilize them reasonably. In addition, the oasis-desert ecotone, as well as the groundwater resources, should be also protected.

浅谈PLC控制系统接地抗干扰技术

PLC控制系统广泛应用与炼铁新厂各个车间，其安全可靠程度直接影响生产过程，在分析几种不同的接地抗干扰技术的性能基础上，针对PLC控制系统存在的各种干扰，充分利用接地技术，结合正确屏蔽，实现抑制和消除PLC控制系统中大部分干扰问题，保证系统安全运行。

Simulation of Revised Puff Trajectory Model in Regional Atmospheric Environmental Risks

[Objective] The aim was to research application of revised puff trajectory model in atmospheric environmental risks simulation.[Method] In the research,theory of puff trajectory model for pollution diffusion in atmosphere in urban areas was analyzed and CALPUFF,a revised puff trajectory model,was applied in prediction on atmospheric environmental risks in Xining City.[Result] The simple puff trajectory model can not be applied for long-distance transport or in complex terrain and airflow field.In contrast,CALPUFF would be applied in urban areas,and complex terrain or underlying surface.With high resolution ratio,it would depict the beginning condition and detailed distribution of pollutants transport and diffusion.For prediction on atmospheric environmental risks in Xining City,northwest wind dominated in Huangshui Valley;north wind dominated in Beichuan Valley;temperature inversion occurred at high altitude.These had a significant effect on the downwind direction in Xining urban district.The simulation results indicated that puffs usually spread along Huangshui Valley and some non-steady phenomena occurred,such as blocking effect by mountains,deformation of puff by airflow field in ridges and influence of valley wind.[Conclusion] The research is of significance for precise prediction on characters,influence and extent of atmospheric environmental risks in cities.