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991.
为了优化22 mm壁厚X80管道施工中环焊缝焊接工艺,采用管线铺设过程中常用的自保护药芯焊丝半自动焊接工艺,研究了不同焊接热输入及焊道排列对焊缝组织和冲击韧性的影响。结果显示,在所研究的热输入范围内,焊道排列对焊缝组织和冲击韧性影响不大;焊接热输入在16 k J/cm以上时,焊缝金属的冲击韧性急剧下降;焊接热输入在10 k J/cm时,焊缝金属的冲击韧性波动较大;热输入在12~15 k J/cm时,焊缝金属的冲击性能最佳。研究表明,X80自保护药芯焊丝对焊接热输入较为敏感,采用12~15 k J/cm的热输入施焊,可确保焊缝金属的冲击韧性满足工程技术要求,此时焊道排列对焊缝金属的冲击韧性无影响。 相似文献
992.
P. MartínezA.M. Eliceche 《Computers & Chemical Engineering》2011,35(8):1478-1487
A methodology to minimize potential environmental impact and operating cost in the selection of the operating conditions of a steam and power plant is presented. A bi-objective mixed integer nonlinear programming problem is formulated and solved in GAMS. Different strategies are implemented successfully to generate the Pareto curve such as: minimum distance to the utopia point, ?-constraint, weighted sum and global criterion. An analysis of the Pareto curve allows the identification of two regions where it is cheaper and more expensive respectively, to reduce the potential environmental impact, providing relevant information to support a decision making process. The economical valorisation of greenhouse gases emissions reduction was also carried out, showing the region of the Pareto curve in which the income would compensate the increment in operating cost, leading to a reduction of the potential environmental impact with no extra cost. 相似文献
993.
994.
Fang Wang Yu-Jie Zhang Yue Zhou Ya Li Tong Zhou Jie Zheng Jiao-Jiao Zhang Sha Li Dong-Ping Xu Hua-Bin Li 《International journal of molecular sciences》2016,17(3)
Nonalcoholic beverages are usually consumed accompanying alcoholic drinks, and their effects on alcohol metabolism are unclear in vivo. In this study, the effects of 20 nonalcoholic beverages on alcohol metabolism and liver injury caused by alcohol were evaluated in mice. Kunming mice were orally fed with alcohol (52%, v/v) and beverages. The concentrations of ethanol and acetaldehyde in blood as well as the activities of alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH) in liver were assessed to indicate alcohol metabolism. The levels of aspartate aminotransferase (AST) and alanine transaminase (ALT) in serum as well as the levels of malonaldehyde (MDA) and superoxide dismutase (SOD) in liver were measured to reflect the alcohol-induced liver injury. The results showed that the treatment of soda water, green tea and honey chrysanthemum tea could accelerate ethanol metabolism and prevent liver injuries caused by alcohol when companied with excessive alcohol drinking. They might be potential dietary supplements for the alleviation of harmful effects from excessive alcohol consumption. On the contrary, some beverages such as fresh orange juice and red bull are not advised to drink when companied with alcohol consumption due to their adverse effects on ethanol induced liver injury. 相似文献
995.
针对长江上游控制性水库群联合调度问题,建立了大规模混联水库群联合优化调度模型,并提出离散微分动态规划(DDDP)和逐步优化算法(POA)相结合的混合方法,实现大规模混联梯级水库群联合优化调度问题的高效求解。在此基础上,结合流域长系列历史径流资料,进行了长江上游控制性梯级水库群调度模拟,分析了联合调度的发电效益;并在此基础上,结合相关研究成果,探究并分析了梯级水库群建成投运后,联合调度对流域水资源的影响。成果表明,梯级水库群的建成及联合调蓄对于长江中下游枯水期的流量补偿效益十分明显,供水、航运以及压咸补淡等综合效益十分显著。 相似文献
996.
高温后大理岩的冲击力学特性试验研究 总被引:1,自引:0,他引:1
利用分离式霍普金森压杆设备对经历不同高温冷却后大理岩的冲击力学特性进行试验研究,得到不同高温作用后大理岩冲击压缩的应力–应变曲线,分析高温后大理岩纵波波速的变化及在冲击荷载作用下的峰值应力、峰值应变、弹性模量随温度的变化规律。研究结果表明,高温后大理岩的纵波波速随着温度的升高近似线性下降;在800 ℃之前,同一冲击加载速率作用下大理岩的峰值应力随着温度的提高变化并不明显,在800 ℃之后,峰值应力迅速减小;在600 ℃之前,同一冲击加载速率作用下大理岩的峰值应变随着温度的提高无明显变化,但在600 ℃之后,峰值应变随着温度的提高近似线性增加;总体上,弹性模量随着温度的升高呈现降低的趋势,且经历的温度越高,弹性模量下降的幅度越大。结合高温后岩石内部微观结构特征的变化,对大理岩冲击力学特性随温度的变化进行分析。 相似文献
997.
998.
999.
《塑料、橡胶和复合材料》2013,42(5):194-202
AbstractSandwich panels are widely used for energy absorbing applications in cases of low and high velocity impacts. The core itself is capable of absorbing energy by progressive collapse, while the skins are necessary for uniformly distributing the local vertical load over the impacted area as well as for the introduction of overall panel bending resistance. In the present work, the failure response of sandwich panels with open lattice cellular cores subjected to low velocity impact is investigated. Experimental tests are performed using a mass drop testing machine. Additionally, a three-dimensional finite element model of the sandwich panels–impactor system is developed using commercial Finite Element (FE) codes. The core homogenisation is introduced in order to improve the efficiency of the FE analysis by reducing the computational time. Numerical results correlate well with experimental data, enabling detailed understanding of the parameters affecting the initiation and propagation of impact damage. 相似文献
1000.