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排序方式: 共有10000条查询结果,搜索用时 31 毫秒
991.
The addition of small quantities of reactive ele ments (RE) or other elements with high oxygen affini ty, usually in the order of 0 1%~0 2% mass frac tion, will result in a beneficial effect on the oxidationresistance to superalloys[1~4].A number of mechanisms have been proposed toexplain the beneficial effect of RE additions on theCr2O3 forming alloys, including physical blocking byRE ions or second phase particles at grain boundaries,pegging effect between the oxide and the … 相似文献
992.
In this paper, experimental data collected in a straight flume having a bed covered by grasslike vegetation have been used to analyze flow resistance for flexible submerged elements. At first, the measurements are used to test the applicability of Kouwen’s method. Then, a calibration of two coefficients appearing in the semilogarithmic flow resistance equation is carried out. Finally, applying the Π-theorem and the incomplete self-similarity condition, a flow resistance equation linking the friction factor with the shear Reynolds number, the depth-vegetation height ratio and the inflection degree is deduced. 相似文献
993.
浅析影响SCR法铸坯质量的因素 总被引:1,自引:0,他引:1
分析了SCR连铸连轧工艺生产铜银合金导线时,铸坯凝固的热阻界、铸模的传热条件、铸坯组织的控制对产品质量的影响。 相似文献
994.
Conventional pile materials such as steel, concrete, and timber are prone to deterioration for many reasons. Fiber-reinforced polymer (FRP) concrete composites represent an alternative construction material for deep foundations that can eliminate many of the performance disadvantages of traditional piling materials. However, FRP composites present several difficulties related to constructability, and the lack of design tools for their implementation as a foundation element. This paper describes the results of an experimental study on frictional FRP/dense sand interface characteristics and the constructability of FRP–concrete composite piles. An innovative toe driving technique is developed to install the empty FRP shells in the soil and self-consolidating concrete is subsequently cast in them. The experimental program involves interface shear tests on small FRP samples and uplift load tests on large-scale model piles. Two different FRP pile materials with different roughness and a reference steel pile are examined. Static uplift load tests are conducted on different piles installed in soil samples subjected to different confining pressures in the pressure chamber. The results showed that the interface friction for FRP materials compared favorably with conventional steel material. It was shown that toe driving is suitable for installation of FRP piles in dense soils. 相似文献
995.
Jungmin Kang 《Progress in Nuclear Energy》2005,47(1-4):672-684
All the civil nuclear energy systems could contribute to the proliferation risk that weapons-usable material might be diverted or misused for the weapons purpose by terrorists or states. Proliferation-resistant nuclear energy systems are of great importance for the peaceful use of nuclear energy by impeding the diversion or undeclared production of weapons-usable material by states. Since the National Alternative Systems Assessment Program (NASAP) carried out the assessment of proliferation resistance of the civil nuclear energy systems in late 1970s, several comprehensive studies have been performed, including the International Nuclear Fuel Cycle Evaluation (INFCE) by the International Atomic Energy Agency (IAEA), the Spent Fuel Standard by the United States National Academy of Science, the Technical Opportunities for Increasing the Proliferation Resistance of Global Civilian Nuclear Power Systems (TOPS) by the United States Department of Energy, the International Project on Innovative Nuclear Reactors and Fuel Cycles (INPRO) Methodology by the IAEA, and the Generation IV Nuclear Energy Systems (Gen IV) by the Gen IV International Forum. However, all these studies appear lack in the interpretation of country-specific proliferation risk that is arbitrary imposed to the specific countries by major nuclear weapons states, even though the countries are members of the Treaty on the Non-Proliferation of Nuclear Weapons (NPT). This paper outlines the assessments of proliferation resistance of the above studies, points out the country-specific proliferation risk, and suggests further studies to increase the proliferation resistance of the civil nuclear energy systems in the specific NPT member countries such as South Korea. 相似文献
996.
饱和土中大直径嵌岩桩纵向振动特性研究 总被引:7,自引:0,他引:7
根据B iot饱和土理论和R ay le igh-Love杆理论,计及土层及桩的径向运动影响,导出了考虑横向惯性效应的端承桩与饱和土的纵向耦合振动频域的解析解和时域半解析解,对比了考虑与不考虑横向惯性效应时,大直径嵌岩桩纵向振动引起的土层复阻抗的异同以及桩顶导纳和时域反射的特征。研究表明:长径比越小,横向惯性效应越明显,而泊松比和激振频率对饱和土层阻抗及桩顶响应也有重要影响。通过工程实例对比表明,当桩的长径比较小时,用考虑横向惯性效应的计算方法可以得到更好的拟合效果。 相似文献
997.
998.
999.
1000.
微弧氧化处理后的钛合金,表面形成的多微孔氧化膜可使其摩擦因数降低且耐磨性得到提高,但这还不能满足某些使用要求.在微弧氧化的基础上再利用脉冲偏压式磁控溅射技术在钛合金表面沉积氮化钛涂层.球-盘磨损试验表明,与微弧氧化相比,其摩擦因数进一步降低且耐磨性进一步提高,这主要是沉积富钛氮化钛使氧化膜的微孔得到了部分或全封闭的覆盖. 相似文献