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31.
程俭中 《西华大学学报(自然科学版)》1997,(2)
本文首先阐述了证明熵增加原理与热力学第二定律两者之间具有等效性的必要性,然后对熵增加原理是热力学第二定律的数学表述作了严格的证明。 相似文献
32.
膨胀混凝土灌注桩的受力分析 总被引:1,自引:0,他引:1
膨胀混凝土灌注桩是一种近年来发展起来的新型成桩方式。本文首先利用弹性理论否定了其承载力提高是单纯由于摩擦力提高的简单解释,然后以试验数据为基础,从三个方面分析了承载力提高的原因:蠕变、固结过程的缩短能加速桩周土承载力的提高;按极限荷载的定义,桩长伸长能充分发挥桩身承载力和桩底承载力;桩端土强度、刚度的提高对桩侧阻力在桩端有明显的增强效应,并对膨胀混凝土灌注桩的设计和施工提出了建议。 相似文献
33.
在科技进步与就业十分复杂的关系中,一个重要的问题是从总体上讲科技进步是增加还是减少就业呢?至今还没有一个令人满意的答案.利用生产函数测定了科技进步对就业增长的贡献率,得到了科技进步增加就业的结论. 相似文献
34.
Cubic boron nitride(c-BN) film was deposited on a Si (100) substrate by the RF-magnetron sputtering.The mainly problems for fabrication of c-BN films are the low purity and high intrinsic compressive stress. In order to solve the two problems, the c-BN film with the buffer interlayer was deposited on the substrate which had been implanted with nitrogen and/or boron ions. The results show: the implantation of nitrogen ions can obviously increase c-BN content and reduce the internal stress slightly; while the implantation of boron shows no obvious improvement to the content of c-BN, which can reduce the internal stress in the film obviously. In addition, it is suggested that the implantation of nitrogen and boron shows the best result, which not only can increase the content of c-BN, but also reduce the internal stress in the c-BN film obviously. 相似文献
35.
36.
《Measurement》2014
The paper deals with the problem of simultaneously enhancing both horizontal and vertical resolution of analog-to-digital converters, with specific regard to low-cost conversion systems. To this aim, the authors propose the combined exploitation of a suitable Compressive Sampling (CS) approach and a proper digital signal processing stage. In particular, starting from a reduced number of digitized samples, the proposed CS-based sampling approach allows to recover an oversampled version of the input signal, whose spectral content is properly shaped to reject the most of in-band noise. The successive processing stage, implementing a low-pass filter, is mandated to drastically attenuate out-of-band noise components.Tests carried out on an actual microcontroller (namely, PIC32MX360L512 by Microchip) evidence the promising performance of the proposed sampling strategy. Results obtained either on single tone or multisine signals highlight a gain up to 3.5 bits in vertical resolution, while the sample rate increases 50 times with respect to the actual one adopted to randomly sample the input signal of interest. 相似文献
37.
《International Journal of Hydrogen Energy》2019,44(40):22632-22642
Multistage hydrogen Knudsen compressor based on the thermal transpiration effect has very exciting prospect for the hydrogen transmission in the micro devices. Understanding of the hydrogen flow characteristic is the key issue for the designs and applications of the hydrogen energy systems. Firstly, the numerical models of the multistage hydrogen Knudsen compressor are established. The distributions of the rarefaction, velocity and temperature at different stages of the hydrogen flow are calculated and presented. Moreover, the dimensional pressure increases of the hydrogen gas flow are analyzed, and the flow behaviors in the microchannel and the connection channel are discussed. Secondly, the numerical simulation at different connection channel height is implemented, and the hydrogen gas flow characteristics in the connection are analyzed. Especially, the performances of the pressure drop in the connection channel under different channel heights are studied, and the hydrogen gas compression characteristics of different cases are compared and discussed. Also, the effect of the connection channel height on the hydrogen gas pressure increase in the microchannel is investigated. The studies presented in this paper could be greatly beneficial for the hydrogen detection and transmission. 相似文献
38.
39.
《Journal of Nuclear Science and Technology》2013,50(7):662-670
In order to evaluate the breached pin behavior in FBR, the breached pin performance analysis code SAFFRON was developed. Based on the results of run-beyond-cladding-breach test in EBR-II as a collaborative program between PNC and U.S. DOE, the following behaviors were taken into cosideration; fuel sodium reaction product (FSRP) formation, resultant fuel expansion, breach extension of cladding and release of delayed neutron precursors into the coolant. Using 3-dimensional elastic analyses by finite element method, breached pin diameter increase is adequately predicted with the reduced Young's modulus of the breached fuel. The delayed neutron signal response in on-line diagnosis was evaluated in relation to the growth of FSRP and breached area enlargement. 相似文献
40.
MG2×125/560采煤机适用于薄煤层开采,近年来随着机组过度的服役,以及产品的更新换代,因齿轮泵全局短缺,配件无法得到保证。为了解决调高系统的事故频发问题,决定对其进行改造,把MG250/591采煤机调高泵更换在MG2×125/560采煤机机组。通过实验模拟与现场使用,证明改造技术切实可行,能够很好地进行摇臂升降。同时,改造后的调高系统能够节省设备费、增加煤炭产值、减少停工损失等费用共计约843 250元,具有良好的社会效应和明显的经济效益。 相似文献