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排序方式: 共有74条查询结果,搜索用时 156 毫秒
1.
《International Journal of Pressure Vessels and Piping》2005,82(5):407-416
Plastic collapse of pipe bends with attached straight pipes under combined internal pressure and in-plane closing moment is investigated by elastic–plastic finite element analysis. Three load histories are investigated, proportional loading, sequential pressure–moment loading and sequential moment–pressure loading. Three categories of ductile failure load are defined: limit load, plastic load (with associated criteria of collapse) and instability loads. The results show that theoretical limit analysis is not conservative for all the load combinations considered. The calculated plastic load is dependent on the plastic collapse criteria used. The plastic instability load gives an objective measure of failure and accounts for the effects of large deformations. The proportional and pressure–moment load cases exhibit significant geometric strengthening, whereas the moment–pressure load case exhibits significant geometric weakening. 相似文献
2.
改进的基于单片机的无线路灯控制系统 总被引:1,自引:0,他引:1
针对目前城市路灯照明系统存在自动化管理水平还不很高、系统可靠性不高等问题,提出了一个改进的路灯集中监控系统。该系统是集自动控制技术、传感器技术、无线通讯技术、监控系统网络技术和软件技术于一体的无线路灯群式控制系统。该系统针对阴雨天气的情况设计了更加完善的控制方案,保证了路灯处于良陛状态,并且能够将故障信息反馈给上位机,减少了以往人工查洵的负担,提高城市道路照明的现代化控制和管理水平。 相似文献
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目前物流运输配送安全管理主要依靠GPS技术进行管理, 缺乏整体安全管理技术手段. 提出了一种物流物联网监控技术. 该技术实现了物联网传感器系统、视频监控系统、单兵可视通话指挥系统、司乘人员终端、通讯系统等技术的综合应用. 通过实际项目应用, 验证了该技术可以广泛应用于实现保障运输安全、提高运输效率、管理运输绩效、处理应急情况等. 相似文献
5.
目前对于吸附分离技术应用于高压、低浓度CO2脱除的研究还较少,在进行相应吸附脱碳工艺设计时也缺少相关的参考数据。为探究13X沸石分子筛对低浓度CO2的动态吸附性能,本文利用动态吸附实验的方法,探究不同条件下低浓度(摩尔分数3%)CO2气体在13X分子筛上的动态吸附性能,得到不同压力、温度、气体流量、填料高度及分子筛规格(尺寸、形状)等因素影响下的13X分子筛对于CO2气体的动态吸附规律及相应的性能指标参数。结果表明:随着吸附压力的升高,13X分子筛的CO2吸附量增加但增量逐渐减小;降低吸附温度、减小气体流量和增加填料高度均有利于增强13X分子筛的动态CO2吸附性能,提高吸附脱碳效果,其中温度及填料高度的变化对于CO2吸附的影响程度最大;实验还发现小尺寸及条状13X分子筛的动态吸附脱碳性能优于其他规格,并根据其特定条件下的出口CO2浓度为50mL/m3时的CO2吸附量指标,给出吸附剂用量与液化天然气(LNG)脱碳工艺处理量的关系系数。 相似文献
6.
《International Journal of Hydrogen Energy》2023,48(35):12935-12948
Hydrogen embrittlement is a widely known phenomenon in high-strength and storage materials. Hydrogen embrittlement is responsible for subcritical crack growth in material, fracture initiation, subsequent loss in mechanical properties, and catastrophic failure. Hydrogen is induced in the material during an electrochemical reaction between the hydrogen, storage materials, and high-pressure gaseous hydrogen environment. Various mechanisms which are responsible for crack development, growth, and fracture have been deliberated and reported. However, the fundamental mechanism of hydrogen embrittlement remains unclear. Several techniques such as linearly increasing stress test techniques (LIST), constant extension rate test (CERT) and slow strain rate testing (SSRT), thermal desorption spectroscopy (TDS), permeation testing (PT), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) have been utilized to determine the amount of hydrogen diffused and available in the hydrogen storage material. The review intends to categorize and provide a clear understanding of the degradation mechanism that occurs during hydrogen embrittlement. The improvement in mitigating the hydrogen embrittlement degradation as a function of modifying the structure and surfaces of the material is established. Prospects for addressing hydrogen embrittlement degradation through further experimental and numerical research are suggested. Lastly, this paper through recommendation endeavors to prevent hydrogen storage tank degradation and reduces high costs associated with the replacement of the component in renewable energy applications. 相似文献
7.
Xiaojun Quan Gang Chen Ping Cheng 《International Journal of Heat and Mass Transfer》2011,54(9-10):2110-2115
Effects of imposed DC electric fields on microbubble growth generated from a rectangular Pt micro-heater (140 × 100 μm) fabricated on one wall of the microchannel under pulse heating are investigated experimentally in this paper. Bubble dynamics and surface temperature response of the microheater during pulse heating are observed and recorded using a high speed CCD and data acquisition system. Measurements of nucleation time and nucleation temperature and heat flux at boiling inception are taken at a fixed flow rate of 0.6 ml/min and pulse width of 1 ms, and with the electric field strength gradually increasing from zero. With increasing electric field strength, it is found that heat flux required for boiling inception is increased, boiling nucleation time is delayed, and nucleation temperature is reduced. Bubble growth is suppressed by the inward dielectrophoresis force acting at the vapor/water interface which is induced by the electric field. As a result, the diameter of the bubble becomes smaller, and the interface instability is suppressed during the bubble growth period. In addition, it is found that multiple nucleate sites appear on the surface of the micro-heater at high heat flux when the electric field is increased to a sufficiently high strength. A map showing regimes of single and multi nucleate sites in a plot of heat flux versus electric field strength is obtained. 相似文献
8.
《International Journal of Heat and Mass Transfer》2007,50(9-10):1982-1992
Numerical analysis has been carried out to figure out the performance of the thermoelectric micro-cooler with the three-dimensional model. A small-size and column-type thermoelectric cooler is considered and Bi2Te3 and Sb2Te3 are selected as the n- and p-type thermoelectric materials, respectively. The thickness of a thermoelectric element considered is 5–20 μm. The effect of parameters such as the temperature difference, the current, the thickness of a thermoelectric element, and the number of thermoelectric pairs on the performance of the cooler has been investigated. The predicted results show that the performance can be improved for the thick element with the large number of thermoelectric pairs or the small cross-sectional area of the element. 相似文献
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10.
电网舞动区域分布图对架空输电线路的防舞设计和改造工作具有重要的指导意义,如何科学合理地绘制电网舞动区域分布图成为亟须解决的问题。基于辽宁62个气象台站1999—2020年冬季历史气象资料,利用广义极值分布模型计算了各气象台站30年、50年和100年一遇舞动极值日数,制定了电网舞动分级原则,利用克里格插值方法得到了气象台站周边地区特定重现期舞动极值日数。最终根据舞动分级原则绘制了辽宁30年、50年和100年一遇电网舞动区域分布图,分别适用于110~220 kV、330~750 kV和特高压交直流线路的防舞动工作。绘制的特定重现期电网舞动区域分布图与辽宁地区历史舞动记录基本吻合,有助于提升电网抵御覆冰舞动灾害的能力。 相似文献