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71.
西藏江达县白格村金沙江右岸于2018年10月11日和2018年11月3日先后发生2次大规模滑坡—堰塞湖堵江事件,溃堰洪水对下游拉哇库区不良地质体的稳定性造成不同程度的影响。为保障下游水电站建设安全,对拉哇库区主要不良地质体建立了基于星载InSAR技术、无人机技术和地面传感器实时监测的“天空地”一体化监测预警体系,以多维空间采集技术获取变形信息,通过智能监控平台对信息及时进行处理、分析和可视化呈现,利用平台、短信等方式向相关人员进行分级告警,取得了较好的应用效果。 相似文献
72.
水电水利工程压力钢管开孔灌浆后,需对灌浆孔严密封堵,处理不好会对工程安全运行留下隐患。在总结国内外灌浆孔常用封堵方案基础上,以某水电站地下埋管为例,建立平面有限元模型,分析其灌浆开孔后管壁应力集中现象,研究了补强板厚度及堵头坡口深度对压力钢管灌浆孔应力集中的敏感性。结果表明,应力集中程度随补强板厚度及堵头坡口深度增加递减,堵头坡口深度对其影响更加敏感。对于地下埋管管壁上开灌浆孔的非高强钢,建议灌浆后孔口进行封堵,补强板厚度宜与钢管壁厚相同,并适当增加坡口深度。当钢管壁厚较大时,堵头坡口深度宜不小于钢管壁厚的1/4~1/3。 相似文献
73.
王方智 《电脑编程技巧与维护》2012,(14):36-37
在ASP.NET招生报名系统中,使用Flash调用摄像头采集学生照片信息。 相似文献
74.
This paper discusses life time prediction of wire bond structure in a power electronic module based on computational approach that integrates methods for high fidelity analysis, reduced order modelling, and life time prediction using reduced order model. This methodology is demonstrated for the design of a wire bond structure in a power electronic module with aim of reducing the chance of failure due to the wire bond lift off in power electronic module when a random load is applied to the aluminium wire. In particular, wire bond reliability of the power module related to the thermal fatigue material degradation of aluminium wire is one of the main concerns. In the power electronic module reliability, understanding the performance, reliability and robustness of wire bond is a key factor for the future development and success of the power electronic module technology, because wire bond lift off failure ignites other catastrophic failures.The main focus in this study is on the application of reduced order modelling techniques and the development of the associated models for fast evaluation and analysis. The discussion is on methods for approximate response surface modelling based on interpolation techniques using Kriging and radial basis functions. The reduced order modelling approach uses prediction data for the electro-thermo-mechanical behaviour of the power module wirebond design obtained through non-linear transient finite element simulations, in particular for the fatigue life-time of the aluminium wire attached to the silicon chip of the wire in the module. The reduced order models are used for the analysis of predicting the life time of the wire bond structure under random load. One of the widely used cycle counting algorithm, so called rainflow counting algorithm is utilised to count the cycles of temperature profile at the a specific point of the wire bond structure in a power electronic module. Using the cycle results from rainflow algorithm mean life time of the wire bond structure is predicted by a linear cumulative damage model such as Palmgren–Miner rule. This model is utilised to predict the mean fatigue life of the wire bond structure. 相似文献
75.
《International Journal of Hydrogen Energy》2019,44(47):26063-26075
The need of fast regulation of electricity production leads to a number of inconveniences occurred to the electric generation system and the electric market, especially to the nuclear power. A new concept to control nuclear power production is posed in order to allow the regulation of the electricity sent to the grid. This concept proposes the joint operation of a nuclear power plant, a coal power plant with postcombustion capture and a methanation plant. The cost effectiveness of this technology and its capability to reduce the CO2 emissions -consumed in the methanation process- are assessed through the design and economic and environmental analysis of a hybrid facility. Mainly due to the increase of the operating hours of the coal-fired power plant, the environmental feasibility of the initial proposal seems to be limited. However, given that benefits are expected in the medium and long-term (2020–2030) for the Power to Gas facility, a future alternative use is proposed. The target of this new alternative configuration will be the storage of CO2 together with the storage of renewable energy. 相似文献
76.
A new fatigue reliability assessment function which takes into account the vehicle and temperature loadings has been developed in this study. The vehicle and temperature loadings are important parameters as they can cause fatigue failure of the welds in a steel box girder. The temperature affects the traffic loading effect by changing the elastic modulus of asphalt pavement. The effect of the temperature difference has been considered based on the measured data and the finite element analysis. Linear regression equations between the equivalent stress and the temperature for different vehicle types have been developed. Using the thermal stress analysis and the rain-flow counting method, the temperature difference fatigue stress spectrum has been determined. Further, a limit equation for the fatigue reliability assessment, which takes into account both the vehicle and temperature loadings, has been developed. Finally, the effects of the temperature and the traffic growth rate on the fatigue reliability of two welding types of Nan-xi Yangtze River Suspension Bridge have been assessed. 相似文献
77.
Thermoplastic pipes are used in all the industrial fields such as water, sewage and gas piping systems and other industrial applications, like the transport of minerals and slurries. The choice of the right piping system's material depends on many criteria. First of all, it depends on the conditions of use of each kind of material. Secondly, it depends on the cost of the chosen material and finally the mastering of the material's scenarios of failure. The last criteria are possible through the mastering of the material characteristics and the capability to detect the failure, burst or crack, before its occurrence. The adopted approach must be proactive to facilitate the prediction of the failure and help the maintenance staff to apprehend the piping system's damage at the right time. In this paper, we chose HDPE pipes as material for our study. Then, we leaded a new approach of failure analysis and prediction using new models. These models are obtained through a modified version of the stress controlled unified theory, a static damage model using burst pressures and a static damage model using the time to failure. For that reason, we used burst pressures of undamaged HDPE pipe instead of ultimate stresses. Then, we created groove notches with different levels of depth. The obtained burst pressures from these pipes have been considered as the residual burst pressures used in our damage models. The representation of the obtained data according to the life fraction gave us an idea about the critical life fraction and then the critical groove depth which can be allowed. This information has been confirmed by three damage models. Then, we determined the different stages of damage to help the predictive maintenance to define the safe intervals of the HDPE pipes' service. Moreover, the three developed models, presented in this paper, represent a simplified approach to assess the damage based on static tests only, without doing any dynamic tests. The developed cost-effective approach can be a tool that can help the industrials to have an anticipative maintenance strategy and respect the safety requirements. Also, it can help them to do quick checks or launch audit mission to the manufacturers' factories for HDPE pipes' quality control and conformity check regarding the codes. 相似文献
78.
《Ceramics International》2019,45(8):9799-9806
(Nb1-xTax)4AlC3 (x = 0–0.5) ceramics were prepared by the hot press sintering method. The XRD results show that the second phase (Nb1-xTax)C is formed when the Ta content increases to 25 mol%. The SEM micrographs show that (Nb1-xTax)C has a core/rim structure, whose formation mechanism was also investigated. Substituting some Ta for Nb can significantly improve the mechanical properties of Nb4AlC3. (Nb0.75Ta0.25)4AlC3 exhibits an excellent fracture toughness of 8.3 ± 0.3 MPa m1/2 at room temperature (RT). The highest Young's modulus (349 ± 16 GPa) and Vickers hardness (4.5 ± 0.3 GPa) at RT are exhibited by the (Nb0.5Ta0.5)4AlC3 sample, which correlate to increases of 18% and 80%, respectively, compared with those of Nb4AlC3. The flexural strengths of (Nb0.5Ta0.5)4AlC3 are 439 ± 18 MPa at RT and 344 ± 22 MPa at 1100 °C, which correlate to increases of 27% and 45%, respectively, compared with those of Nb4AlC3. The solid solution of Ta and the formation of (Nb1-xTax)C are beneficial to the strengthening of Nb4AlC3. The coefficient of thermal expansion (CTE) increases slightly from 7.08 × 10−6 K−1 for Nb4AlC3 to 7.24 × 10−6 K−1 for (Nb0.75Ta0.25)4AlC3 at 25–1400 °C. The thermal conductivity of (Nb0.75Ta0.25)4AlC3 (28.4–29.8 W/m·K) is higher than that of Nb4AlC3 (18.1–21.2 W/m·K) over the whole test range (25–1000 °C). Owing to their excellent mechanical and thermal properties, Ta-doped Nb4AlC3 ceramics have good potential as structural materials. 相似文献
79.
80.
介绍了自行研发的全电AMT系统的组成、原理及其动力一体化转矩控制策略。通过分析AMT车辆换挡过程中对发动机、离合器和变速器的综合控制及其对换挡品质的影响,提出了AMT车辆升挡过程中转矩控制策略,并在装有AMT的某轿车上进行了试验。试验结果表明,在升挡过程中采用一体化控制策略,改变发动机点火提前角和断油能够快速调节发动机转矩,有效地提高了全电AMT车辆的换挡品质。 相似文献