Theoretical Analysis and Experiment Study of Ferrule Needle Valve

针阀是现代工业领域重要的执行或调节元件之一，广泛应用于石油、化工、市政、电力等关系国计民生的重要领域。卡套针阀是针阀的一种，具有较高的流量调节精度、较好的流量调节线性度，由于采用了卡套式接头，卡套针阀还具有优秀的接头快速密封性能，具有广阔的市场前景和研究价值。本文主要工作如下： (1)在充分研究了卡套针阀工作原理的基础上，根据阀门设计手册、《MSSSP-99仪表阀门》等技术标准，对卡套针阀进行了总体结构设计，用Solidworks建立了相应的三维模型；计算校核了阀体壁厚和阀杆强度，并运用有限元分析软件Patran/Nastran进行了有限元分析验证；分别研究、推导了金属和填料密封原理，并求解...The needle valve is an important executive component in modern industry, it’s widely used in petroleum industry, chemical industry, municipal construction, electric system and some other important areas. Ferrule needle valve is one branch of needle valve which with higher flow regulation accuracy, better flow regulation linearity. As a result of using bite type tube fittings, the interfaces of fer...学位：工学硕士院系专业：物理与机电工程学院_机械工程学号：1992010115273

基于MD_Nastran的双卡套管接头性能分析

双卡套管接头各组件形成密封的过程是典型的边界条件高度非线性问题。文中基于Md_nASTrAn的SOl600模块对某型12MM内径的双卡套管接头进行了隐式非线性分析,确定了该型双卡套管接头形成有效密封后各组件的应力大小、应力分布等关键性能参数,为该型双卡套管接头的改进和后续研发提供了有益的参考

The Improvement of Cultural Practice for Sweet Potato production

影響甘藷產量及品質的因子，可分為人為和自然因子兩類，人為因子為品種、栽培技術及輪作制度。自然因子為氣候、土壤生產力和肥力等。選用適地適作已經推廣栽培的優良品種，並針對該優良品種的特性，配合適當的栽培管理方法，如採用優良藷苗、適當插植時期和方法、合理的種植密度、適量適時的施肥、適度適時的灌溉，適時防治病蟲害及適時培土等，這些都是提高甘藷質和量生產的重要條件。目前由於農村耕作勞力的不足，運用現有可行的適當農機具，使生產過程中重要的栽培作業，達到機械化，也是增加生產利益的重要工作，在計畫生產時，必須注意不同季節和不同用途之產品市場的需求情形，做好產期調節，才能達成生產的好處。甘藷有良好的營養價值，然而如何使其生產和利用相互結合，是應加以重視的問題。 Factors affecting the yield and quality of sweet potato can be classified into two groups; those factors originated from the nature include climate, soil productivety and fertility, and the prevalence of insects and diseases. Impacts from the human beings include varietal performance, cultural practices, and other measures such as capital investment and consumers¡¦ preference. The enhancement in yield and quality of any crop can be achieved by developing varieties capable of matching the environmental conditions under appropriate cultural practices. For sweet potato, major concerns related to cultural practices include the selection of high quality vine cuttings and the optimum decision in planting time, planting method, planting density, fertilization, irrigation, soil banking, and insect and disease management. Due to the shortage of farm labor, the development of mechanization, especially for planting and harvesting, is also essential to the successful production of sweet potato. In order to increase farmers’ profit, the adjustment of harvest time to meet market demand should be considered. Sweet potato is a better diet as compared to rice in terms of its higher nutritional value and dietary fiber content and lower calorie content. Studies are needed to expand its utilization and to develop modern processing techniques in order to facilitate the production of this important food crop