Nondestructive Electrical Resistivity Method to Map the Drainage System of Football Playgrounds

Geophysical surveys could contribute significantly to remediation programs for damaged buried engineering structures. Resistivity profiling and mapping techniques used in this work allow rapid and one of the most cost-effective ways of characterization and visualization of internal defects of drainage and watering systems of football playgrounds in a nondestructive way. Cost-effective and nondestructive testing can be valuable assets for diagnosis, realization, and restoration of football playgrounds.     

基于智能化高压电力设备的状态监控系统设计

本文分析了电力设备的状态监控与诊断技术,提出了状态监控与诊断的构成框架,给出了基于状态监控与诊断的智能化高压电力设备的测试方法.     

位图方法在电阻抗断层成像中的应用

借助插值方法根据有限元节点数据计算出需要显示图像的像素点数据,通过位图方法将结果显示与后处理应用于电阻抗断层成像系统中,实现了一种在Windows环境下基于有限元方法重构的电阻抗断层成像显示处理的新方法。此方法的实现简单可行、结果可靠。     

管式SOFC数学模型及系统性能分析

固体氧化物燃料电池(SOFC)是一种高效低污染的新型能源。该文基于物质和能量守恒并耦合流体流动、热量产生和传递以及电化学知识建立了以天然气为燃料的管式固体氧化物燃料电池的数学模型,对模型进行求解,并分析系统参数(电流密度、工作压力、燃料的摩尔流量等)对系统性能(发电量、发电效率等)的影响。结果表明:SOFC系统的发电效率可以达到50.73%。通过增加单电池个数来减小电流密度可以增加系统发电量和发电效率,但是会增加系统投资;增大燃料电池的工作压力可以改善系统的性能;而增加燃料的摩尔流量(燃料利用率不变)会使系统的发电效率降低。     

Coagulation process of soymilk characterized by electrical impedance spectroscopy

Soymilk coagulation process is the most important step in tofu making. An experimental setup was developed to control the coagulation temperature and heating rate by ohmic heating and to perform impedance measurement in time-sharing mode. Soymilk coagulation process was characterized by electrical impedance spectroscopy. Frequency 10 kHz was chosen to analyze the coagulation process. Normalized conductivity was useful in determination of the endpoint of soymilk coagulation process. The coagulation process was considered as two successive first-order reactions. The rate constant in the first stage was 10 times higher than that in the second stage, both rate constants increased with coagulation temperature. The activation energy in the second stage was three times greater than that in the first stage. The successive reaction process was elucidated by using soymilk coagulation mechanism. The use of impedance measurement to analyze the coagulation process provides a basis for the control of soymilk coagulation process.     

Structural hierarchy developed in injection molding of nylon 6/clay/carbon black nanocomposites

The influence of platelet-type clay nanoparticle (nanoplatelet) on the structural evolution in injection-molded nylon 6)/carbon composites was investigated. In the absence of nanoplatelets, the nylon 6/CB systems were found to exhibit unoriented structure with nylon 6 crystalline regions exhibiting exclusively α crystal form throughout the thickness of the samples. However, inclusion of nanoplatelets induces substantial local orientation of the nylon 6 chains in the molded parts in all processing conditions and compositions. In these clay/nylon 6/CB ternary nano systems, nylon 6 matrix was found to be exclusively in γ crystal form at the skin regions and α crystal form fraction increases towards the core of the molded parts as a result of decrease in cooling rate with depth during the solidification stage. Two nanoplatelet orientation behaviors were identified: (i) in the absence of irregular shaped CB, the nanoplatelets align parallel with one another following the local flow patterns. The latter behavior also causes enhanced orientation of the nylon 6 chains undergoing substantial shear amplification trapped in between the nanoplatelets (ii) in the CB-enriched regions, nanoplatelets though still remaining parallel to one another, are randomized by following the local contours of irregular shaped CB aggregates. These CB aggregates themselves were found to organize to form trains in larger scale as a result of flow alignment.     

电容层析成像系统传感器参数优化——基于正交试验设计法

介绍了电容层析成像系统的工作原理及数学模型,采用有限元分析对传感器灵敏度分布进行仿真,分析了系统中各个传感器参数对传感器性能的影响,提出传感器性能评价函数,并基于正交试验设计确定了一组优化参数,为电容层析成像系统中传感器的设计提供了参考依据。     

单相复费率电子式电能表的设计

目前在电能计量和收费当中使用最多是的是机械表和电子式电能表,这些电能表只能完成计量功能而不能完成分时付费功能,随着科学技术与国民经济的发展,对分时付费功能的需求越来越多,针对这种情况研发出了一种能够按照时段进行分时付费的电子式电能表,克服了现有电能计量中存在的不能分时付费的问题,可以满足电能表用户和供电部门的需求.     

A study on electrical conductivity of chemosynthetic Al2O3–2SiO2 geoploymer materials

Al₂O₃–2SiO₂ amorphous powders are synthesized by sol–gel method with tetraethoxysilane (TEOS) and aluminum nitrate (ANN) as the starting materials. The microstructure and phase structure of the powders are investigated by SEM and XRD analysis. Geopolymer materials samples are prepared by mechanically mixing stoichiometric amounts of calcined Al₂O₃–2SiO₂ powders and sodium silicate solutions to allow a mass ratio of Na₂O/Al₂O₃ = 0.4, 0.375, 0.35, 0.325, 0.288, 0.26, 0.23 or 0.2 separately, and finally to form a homogenous slurry at a fixed H₂O/Na₂O mole ratio = 11.7. The results show that the synthetic Al₂O₃–2SiO₂ powders have polycondensed property and their compressive strengthes are similar to that of nature metakaolin geopolymer materials. The results also show that the water consumption is not the main influencing factor on electrical conductivity of harden geopolymer materials but it can intensively affect the microstructure of geopolymer materials. In addition, the electrical conductivity of harden geopolymer sample is investigated, and the results show that the geopolymer materials have a high ionic electrical conductivity of about 1.5 × 10⁻⁶ S cm⁻¹ in air at room temperature.