贯穿斜裂纹应力强度因子的计算

利用有限元方法计算了不同长度贯穿斜裂纹前沿应力强度因子,分别计算了β为45°、60°和75°三种情况,得到裂纹前沿应力强度因子的分布规律,以及应力强度因子随着角度的变化规律。弥补了应力强度因子手册中对这种裂纹计算的不足。     

提高喷雾模拟精度的算法

燃油喷雾是直喷式发动机燃烧的关键过程,喷雾模拟的精度决定了燃烧计算的可靠性．然而,在KIVA和商业CFD代码中,传统喷雾模拟技术对网格精度非常敏感．因而,预测的发动机性能和排放依赖于计算网格．导致这个问题的两个主要原因是液滴碰撞算法和气液相间耦合．为了提高喷雾模拟精度,采用交错网格液滴碰撞（CMC）算法和气相速度插值算法对原始KIVA代码进行了修正．在定容燃烧室和直喷式柴油机条件下,分别从喷雾结构、预测平均液滴尺寸和喷雾贯穿距三个方面检验了改进KIVA代码对喷雾模拟精度的改善．结果表明,网格依赖性显著降低．通过这些改进,喷雾结构的失真现象消失．在定容燃烧室计算中,预测的平均液滴尺寸的不确定性从30μm减小到5μm;在发动机模拟中,这种不确定性进一步减小到2μm．在中等和精细网格条件下,发动机模拟预测的喷雾贯穿距也获得了较好的一致性．     

切管自动送料装置的设计

在以各种管材为原料的产品生产过程中,管件切割的送料方式直接影响到切割的精度和生产效率,继而影响产品的质量和成本。目前管材切割的送料方式大都是人工操作,切割精度和效率低,劳动强度大。根据管材自动切割的精度、效率、安全性和稳定性等方面的需求,对自动送料装置的驱动、传动和控制方式等进行了设计。通过步进电机和滚珠丝杠传动机构进行自动送料,气动驱动组合夹具进行不同数量和截面形状管材的可调装夹,参照企业生产需求设计了机架,装置实现了管材切割送料的自动化。     

基于函数贯穿的C语言计算思维训练

针对高职院校学生的认知特点与学习习惯,以及C语言程序设计教学的现状,提出基于函数贯穿的C语言程序设计教学内容与教学改革方法,教师作为引导者,通过引导程序阅读与编码示范,让学生跟随训练,模仿训练、仿真实训,引导学生领悟程序逻辑与思维,培养其计算思维以及良好的程序语言学习方法与编码规范、习惯,从而提高程序语言学习效率。     

AP1000电气贯穿件安装工艺

摘 要：对AP1000电气贯穿件的结构、安装要求进行了介绍,对电气贯穿件的现场安装工艺进行了研究。     

钢丝绳芯平板硫化机成型车结构设计与制造

简要介绍钢丝绳芯输送带平板硫化机辅机成型车的设计方案,结构特点,技术性能参数,该机的成功研制,提高了钢丝绳芯输送带平板硫化机在国内市场的竞争力.     

氧化锌压敏电阻磨片工艺改进

本文主要对压敏电阻的磨片工艺进行了探讨,并提出了一种新的磨片工艺双端面研磨工艺.该工艺采用贯穿送料和连续磨削的方法实现对电阻片的研磨.经试验和批量验证,该工艺有效消除了四道平磨工艺对电阻片边缘的磕碰问题,同时,其效率、成本等与四道平磨工艺相比优势明显,具有优异的性价比.     

Linkages of transboundary water allocation and its eco-thresholds with international laws

Based on the case study of Lancang-Mekong river, analyses have been made on the database of bilateral and multilateral treaties/agreement of transboundary water resources in the world and the regional agreements of Mekong River, the principles of the equitable and reasonable utilization, and causing no significant harm, index system and related models on transboundary water allocation have been worked out, and the key ecologic thresholds of the maximum and minimum water flow and water level of water allocation have been defined. By using the data of water resources development and utilization at present and development objectives of the riparian states, to ensure the ecological environment demand of water in the river basin and based on the water yields in the riparian states, 5 types of 3 kinds of water allocation schemes with water volume as the core have been set up, viz., the whole allocation, the project allocation and the river-basin-integrated allocation. By comparing the scheme, the results show tion scheme can equitably beneficial effect of each that （1） the whole allocadefine the available water consumption volume of each state, but cannot sustain the ecological objectives in the river basin; （2） the project allocation scheme can meet the needs of the most riparian states, but cannot meet the drainage ecologic need （esp. to prevent the intrusion of saltwater in Mekong Delta） and the development objectives of Vietnam; （3） the integrated allocation scheme can meet the development need of each state in the predictable period and sustainability of drainage ecology, but the beneficial countries should make compensation to the others so as to materialize the fairness of transboundary water allocation.     

Transboundary hydrological effects of hydropower dam construction on the Lancang River

Ecological and socioeconomic issues in the Greater Mekong Subregion have in recent years attracted increasing regional and global attention. Much of this concern has been centered on construction of a cascade of hydropower dams on the Lancang River （upper Mekong River） in southwestern China＇s Yunnan Province, This article uses monthly runoff data of hydrologic monitoring stations in the Lancang River watershed from the 1950s onward and key data of the partially completed 2-dam cascade on the main stream of Lancang River to perform a comprehensive analysis of possible transboundary hydrologic effects of dam construction on Lower Mekong River. Results of the analysis show the following： （1） changes in flows over the Lancang-Mekong river＇s 4880 km course are exceedingly complex, and the two existing dams on the mainstream of Lancang River are but one of many factors influencing those flows, not a major factor; （2） significant downstream impacts of the two existing dams are limited in scale to changes in daily flow stages, and are limited geographically to the narrow channel north of Vientiane; （3） over timescales of several days or more, the primary factor in flow changes is climate change; （4） below the Yunjinghong hydrologic station in Lancang River basin, flow volumes can be as great as 113.7×10^8 m^3, or 15.44% of the average annual total runoff out of China, now are not influenced by the dam construction. These results provide a scientific basis for reasonable assessment of transboundary impact of dam construction on the mainstream of Lancang River to the lower Mekong River.     

将写字练习贯穿于语文教学中

中国的书法艺术被称为＂国粹＂,在世界艺术中独树一帜,中国的书法艺术正以其独特的话语方式与世界对话,它是中国递向世界的一张名片。书法教育在整个国民教育中占有重要的地位,写字则是一项重要的语文基本功。