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101.
本文介绍了一种基于模糊控制的中压异步电动机软起动器的原理和软硬件设计。根据对电动机起动特性的分析,提出了基于模糊控制的中压电动机软起动的设计方法。通过检测输入电流,在电动机起动过程中,在恒流平滑升压下有效的消除了启动过程中的电流振荡问题,以达到最佳的起动效果。 相似文献
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Routine inspection of oil and gas pipes for time dependent degradation is essential. Pipelines are most commonly inspected using In-Line Inspection (ILI), however restrictions from pipe geometry, features or flow rate can prevent its use. Facility pipework rarely facilitates ILI, and external inspection often warrants the undesirable removal of the pipe insulation and cladding. This work investigates the applicability of a current deflection non-destructive evaluation technique for both the detection and growth monitoring of defects, particularly focusing on corrosion. Magnetic sensors are used to monitor variations in the spatial distribution of the induced magnetic flux density outside a pipe that arise from deflection of an injected electric current around inner or outer wall defects. An array of orthogonal magnetoresistive sensors has been used to measure the magnetic flux density surrounding six-inch schedule 40 seamless and welded carbon steel and austenitic steel pipes. The measurements were stable and repeatable to the order of 100 pT which suggests that the defect detection or growth monitoring of corrosion-type defects may be possible with a few amps of injected current when measurements are taken at around 50 mm lift-off. The sensitivity of the technique is dependent on factors including defect geometry, sensor lift-off, bends, variations in nominal pipe geometry or material properties, and the presence of ferromagnetic objects, each of which were investigated using either experiment or a validated finite element model. 相似文献
106.
The quarterly Literature Listing is intended as a current awareness service for readers indicating newly published books, journal and conference articles on: patent search techniques, databases, analysis and classifications; patent searcher certification; patents relating to a) life sciences and pharmaceuticals and b) software; patent policy and strategic issues; trade marks; designs; domain names; and articles reviewing historical aspects of intellectual property or reviewing specific topics/persons. The current Literature Listing was compiled end-November 2015. Key resources used are Scopus, Digital Commons, publishers' RSS feeds, and serendipity! Please feel free to send the author details of newly published reports/monographs/books for potential inclusion. 相似文献
107.
利用田野调查方法,对高桥手绣的发展现状及制作工艺流程进行了探讨和分析。通过寻访和记录手绣传人生存状态及手绣工艺过程的方式,对高桥手绣订单式加工、原材料缺乏、传统手绣品类消失、手绣从业人员急剧减少的发展现状,以及高桥手绣代表性品种手绣荷包的制作工艺流程即取样、绣制、缝合、缝坠子,进行了详细而深入的记录、复原、分析与研究。 相似文献
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本文从建筑结构教育现状暴露出的现实问题出发,对全过程设计阶段的建筑与结构的综合关系作了详细的探讨,希望读者能对结构在建筑中的作用有进一步的认识,从而提高结构设计的技术内涵和品质。 相似文献
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《International Journal of Hydrogen Energy》2019,44(31):16965-16975
One of the ways to generate clean and non-destructive energy is to use the energy stored in the biomass resources by the microbial fuel cells (MFCs). Sediment Microbial Fuel Cells (SMFCs) are a special type of MFCs that use organic materials in aquifers sediment to generate electricity. In this research, the effects of an increase in the electrode surface are investigated. The results showed that the increase in cathode electrode surface had better efficiency than the multi-cathode mode (maximum power generated for a 3-cathode electrode (27 cm3) and 1-cathode electrode (27 cm3) was 526 mW/cm2 and 800 mW/cm2, respectively. Another parameter affecting the performance of these systems is temperature. In the next step, the power generation rate was measured in different step currents and at different sample times. In the final stage, a power management system (PMS) was designed to optimally utilize the output energy of the improved SMFC, leading to an increase in the output voltage to 3.3 V. 相似文献
110.
《Measurement》2016
Wafer-level characterization of functional prototypes of solid state current sensors is usually the first step in the development stage, therefore a dedicated wafer-level measurement systems are required. Especially for MHz characterization, where electromagnetic interference issues became strongly relevant. Thus, for frequencies above 1 MHz, a sophisticated measurement techniques are needed, because parasitic couplings can significantly affect sensor response and other signal processing stages, causing errors or malfunction of the whole system. We propose technique for high immunity MHz current measurement by solid state sensor in wafer-level configuration. The system is especially well-suited for MHz characterization, where electromagnetic interference issues become highly relevant. We showed that balanced transmission provides possibility to reduce interference in the sensor biasing circuit of about 60 dB compared to single-ended method. The effectiveness of the proposed technique was tested in monitoring MHz current in the external line by single magnetoresistive sensors on wafer level. 相似文献