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弹粘塑性孔隙介质在冲击荷载作用下的一种本构关系——第二部分:弹粘塑性孔隙介质的畸变行为 被引量:5
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作者 戚承志 王明洋 钱七虎 《岩石力学与工程学报》 EI CAS CSCD 北大核心 2003年第11期1763-1766,共4页
继发表在本刊2003年第9期上第一部分的研究,就弹塑性孔隙介质在冲击偏应力张量作用下的行为进行了研究。考虑应变率对材料强度的影响,给出了热活化机理与宏观阻尼机理相互竞争的联合强度-应变率依赖模型。考虑应力状态、应变强化、畸变... 继发表在本刊2003年第9期上第一部分的研究,就弹塑性孔隙介质在冲击偏应力张量作用下的行为进行了研究。考虑应变率对材料强度的影响,给出了热活化机理与宏观阻尼机理相互竞争的联合强度-应变率依赖模型。考虑应力状态、应变强化、畸变损伤和与孔隙率相联系的损伤对材料强度的影响,并在此基础上基于热活化原则给出了松弛型的应力偏量与应变偏量之间的关系,且本模型符合热力学第二定律。 展开更多
关键词 岩石力学 弹粘塑性 孔隙介质 冲击荷载 本构关系 松弛型关系
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A New Control Approach of a Three-Phase Inverter Two Levels
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作者 François Yonga Colince Welba +1 位作者 Theodore Louossi Noël Djongyang 《Open Journal of Energy Efficiency》 2022年第3期55-70,共16页
In this paper, we present the study, modelling and simulation of the duty cycle modulation (DCM) based on SVPWM control technique using Matlab/Simulink software. It is one of the most advanced control techniques of sp... In this paper, we present the study, modelling and simulation of the duty cycle modulation (DCM) based on SVPWM control technique using Matlab/Simulink software. It is one of the most advanced control techniques of space vector modulation (SVM), which can be used for controlling static converters or for controlling electrical machines to achieve better dynamic performance. DCSVM is a control technique that generates control signals for the two-level voltage converter as well as for the intermediate times. The main advantage of this control technique is the reduction of the number of calculations, especially for the trigonometric functions and the generation of the reference voltage. In order to reduce the computational effort, we have designed a DCSVM controller that is able to faithfully reproduce the same vectors and output quantities as a classical SVM. In order to test the functionality and validity of the DCSVM control, we have developed different simulations that result in a total harmonic distortion (THD) of the voltage and current of 41.19% and 15.19% respectively with fundamental values of 61.51 V for the voltage and 2.80 A for the current;in contrast to the SVM which gives 47.27 V for the voltage and 2.01 A for the current with THDs of 77.16% for the voltage and 16.00% for the current. This results in an improvement in the distortion rate of around 25.5%. The results obtained are very satisfactory. The DCSVM is a real competitor to the SVM and its various variants. 展开更多
关键词 INVERTER SVM (Space Vector Modulation) DCSVM (Duty Cycle Space Vector Modulation) HARMONIC THD (Total Harmonic distorsion)
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框架梁的畸变屈曲:隅撑还是加劲肋
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作者 童根树 《钢结构(中英文)》 2022年第12期45-47,共3页
介绍了独立支撑和相对支撑的概念,指出框架梁之间设置的隅撑是相对支撑,其发挥作用的前提是另一根构件有富余度,即隅撑作用具有不确定性。故建议采用离开柱面1.5倍梁高处设置加劲肋来避免框架梁的畸变屈曲,同时给出了不设隅撑的条件。
关键词 畸变屈曲 框架梁 隅撑 加劲肋
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