油井管特殊螺纹力学损伤与控制研究进展

油井管螺纹失效是目前油气田开采作业中常见且难以治理的事故之一,这一情况不仅制约开采进度,而且威胁井下安全。普通螺纹存在密封性能差、承载能力低、抗腐蚀能力弱等问题。主要从疲劳失效、密封失效、腐蚀失效三个方面阐述了油井管特殊螺纹接头力学性能的研究进展以及控制方法。在介绍油井管特殊螺纹接头发展历史进程的基础上进一步阐述目前油井管特殊螺纹接头的发展情况,指出当下中国油井管特殊螺纹研究所存在的不足,并提出油井管特殊螺纹力学性能未来研究的新方向。     

基于类型系统的完整性信息流控制

构造了一种实现完整性信息流控制的安全类型系统.首先,为π-演算建立具有完整性安全等级的安全类型.然后,建立该安全类型的子类规则和类型规则,这些规则实现了系统的完整性策略及对系统行为的限制.最后,证明该类型系统的类型合理性,表明满足初始安全策略的系统经过不断的演进、交互,系统的安全属性依然可被满足.所建立的完整性信息流控制机制可通过静态类型检验高效实现.     

Microstructure and properties of in-situ synthesized Cu-1 wt%TiC alloy followed by ECAP and post-annealing

A dispersion-strengthened copper alloy with 1 wt% TiC for commercial electrical-contact wires was prepared by in-situ reaction casting, grain-ultrafining by equal-channel angular pressing (ECAP) and subsequent annealing with aim to obtain excellent comprehensive performance. The results showed that fine TiC particles were in-situ synthesized in the as-cast Cu matrix and aggregated in clusters, and thus mechanical properties of the as-cast alloy deemed insufficient. Continued ECAP at 473 K significantly refined the grains of the as-cast alloy and improved the distribution of TiC particles. Due to multiple strengthening mechanisms, the ECAP-processed alloys maintained good conductivity with obviously enhanced tensile strength and hardness values. After post-ECAP annealing, the elongation and conductivity of the fine-grained copper alloy increased with the adequate tensile strength. The novel combined process endows the alloy appropriate performance to serve current high-frequency electrification railway systems.     

浅谈《机械制图与AUTO CAD》精品课程的建设

我院一直致力于《机械制图与AUTO CAD》课程建设,本文结合该课程的发展历程,从课程体系、教学内容、教学方法、教学手段、教材建设及实践教学等方面,对精品课程建设的基本思路进行了阐述。     

《机械制图》课程“项目化”改革的实践探索

项目课程是一种以工作任务为中心,选择、组织并学习工作知识的课程模式,它是当前我国职教课程改革的主要方向。该文以《机械制图》为例,系统介绍了该课程的"项目化"方法。包括课程结构的设计、项目选择和设计、教学方法手段的选择等。     

具有历史特征的Biba模型严格完整性策略

针对Biba模型中的严格完整性策略在保证数据完整性的同时会降低系统兼容性的问题,在Biba严格完整性模型基础上提出了具有历史特征的Biba模型严格完整性策略,将主体完整性等级扩展为独立的读写区间,并根据主体读写历史调整主体可读写的区间,并给出形式化的描述.该模型既可以保护系统数据的完整性,又能提高系统的兼容性.同时,给出所构造规则的实施策略的实现算法,说明该实施策略和常规实施策略具有相同的时间复杂度.     

MA法制备复合材料常用设备的比较分析(综述)

简述了机械合金化常用设备的工作原理及特点,分析了机械合金化设备对制备颗粒增强金属基复合材料的影响因素,为制备复合材料的设备选用及工艺的设计提供依据,并对球磨机的研究与开发提出了技术展望.     

古机械复原研究的方法与程序

古机械的复原是以一古机械原型为本体,根据古代的机械原理、机械工程、以及工艺技术等,重新建构此一机械.本研究以古中国机械为对象,根据史料成分进行分类,并提出一复原研究程序,有系统地建构古机械原型及古代机械科技和工艺,目的在提供研究机械史学领域的一个创新方法.     

高速电路中电源/地平面间同步开关噪声的抑制研究

提出一种将介质型电磁带隙结构与电源平面分割技术相结合,用于抑制高速电路电源/地平面间同步开关噪声的新方法.利用Ansoft HFSS建立相应三维电磁仿真模型并对其进行数值仿真,结果表明:若以-40 dB为噪声隔离标准,噪声可在0.01～0.66 GHz与0.91～4.11 GHz范围内得到有效抑制,并且噪声最大抑制深度...     

Effect of heat treatment on microstructures and properties of a novel Al-Zn-Mg-Cu alloy for oil drilling

In view of the special requirements for strength, heat resistance and corrosion resistance of Al-Zn-Mg-Cu alloy for oil drilling, the Al-6.2 Zn-2.5 Mg-1.6 Cu alloy was prepared by increasing Cu content on basis of Russian Series 1953 alloy. The effect of heat treatment on the microstructures and properties of the alloy was characterized by optical microscope(OM), scanning electron microscope(SEM) and transmission electron microscope(TEM), and investigated by tensile test at room temperature, thermal exposure test and corrosion test. The results show that the strength after T6 aging treatment exhibit a decrease trend as an increase of the solution temperature from465 °C to 480 °C. After the solution treated by the rate of 470 °C/1 h, second phases dissolve into the matrix very well and the strength property reaches optimum. The alloy has better comprehensive properties treated by a solution treatment of 470 °C/1 h and then followed by an aging treatment of 120 °C/24 h + 170 °C/1 h + 120 °C/24 h. Under the aging state, the precipitated phases inside the grains are suitable in size, while on the grain boundary distribute discontinuously and the precipitate-free zone is obvious. Besides, the alloy still maintain high tensile properties. The yield strength, tensile strength and elongation are 650 MPa, 686 MPa,12.0%, respectively. The yield strength retention after heat exposure is 92%. The alloy has good corrosion resistance and the exfoliation corrosion degree. The average corrosion rate in the H_2S and CO_2 environment is 0.0024 mm/a, which is far less than the required 0.12 mm/a. It is insensitive to H_2S and CO_2 environments.