基于ISO13584标准的管螺纹三维实体模型的实现

依据ISO13584标准开发了管螺纹的中性程序,同时开发了数据接口(编译器),在具体的CAD平台UG上,把中性程序转化为UG可以识别的GRIP程序。阐述了管螺纹实体模型实现的算法,曲线经过螺旋运动重合于一点,从而生成B曲面。文中举例介绍了该算法的实现过程。

Correlation between pre-peak in structure factor and physical properties in Al-based amorphous alloys

To study the influence of Fe addition on the Al-based amorphous alloys,the structure and properties of Al84Ni10La6 and Al84Ni9Fe1La6 alloys were investigated through various techniques.The results show that 1% Fe（molar fraction） addition increases the area of the pre-peak in the structure factor and decreases the thermal expansion coefficient difference between the crystalline and amorphous states.1% Fe addition also improves the glass forming ability（GFA）,micro-hardness,fracture toughness,electric resistivity,absolute diamagnetism and corrosion resistance of Al-Ni-La alloys,which is related to the changes of medium-range order and quench-in free volume caused by 1% Fe addition.

Supply Problems of Sales Points Performance in City Centres： Results of the DORED Program Survey Research

The paper regards to problems of sales point performance being situated in the centres of big cities in Poland. Problems are investigated with the use of surveys being carried out in 900 sales points according to author＇s DORED （DORED-dobre rozwiazania dla dostaw in Polish, good solutions for delivery in English） program performance. The DORED program has been mentioned for the first time in Logistics （a Polish newspaper） in February, 2005. The developed topic has been the pilot project of DORED program. That was in Wroclaw City （Poland）, where the regions of Przedmiescie swidnickie were the first test of method of the DORED program. The mentioned topic has encompassed the city logistic problems, land transportation and movement organization performance in the city centres.

Comparison of Minimum Energy Performance Standards (MEPS) Programs in the USA and China

Abstract： Nowadays energy saving and environmental protection are crucial issues in the international society. One of the best solutions for both issues is to improve energy efficiency. To improve energy efficiency, it is commonly recognized by both standards and energy sectors that Minimum Energy Performance Standards （MEPS） could play an important role . China and the USA, the top two energy consumption countries in the world, both have adopted MEPS program to address the problem of energy conservation and environmental protection. This paper analyzes and compares the two countries＇ MEPS programs from a historical and legal context, examining the role of different stakeholders in the process,the process, the outcomes by standards,and then makes some recommendations for both sides.

Performance of Steel Structures under Fatigue Cyclic Loading

A component or structure, which is designed to carry a single monotonically increasing application of static load, may fracture and fail if the same load or even smaller load is applied cyclically a large number of times. For example a thin rod bent back and forth beyond yielding fails after a few cycles of such repeated bending. The fatigue failure is due to progressive propagation of flaws in steel under cyclic loading. This is partially enhanced by the stress concentration at the tip of such flaw or crack. The presence of a hole in a plate or simply the presence of a notch in the plate has created stress concentrations at the center points. These stress concentrations may occur in the material due to some discontinuities in the material itself. At the time of static failure, the average stress across the entire cross section would be the yield stress. However when the load is repeatedly applied or the load fluctuates between tension and compression, the center points experience a higher range of stress reversal than the applied average stress. These fluctuations involving higher stress ranges, cause minute cracks at these points, which open up progressively and spread with each application of the cyclic load and ultimately lead to rupture. Fatigue failure can be defined as the number of cycles and hence time taken to reach a pre-defined or a threshold failure criterion. Low cycle fatigue could be classified as the failures occurring in few cycles to a few tens of thousands of cycles, normally under high stress/strain ranges. High cycle fatigue requires about several millions of cycles to initiate a failure. The type of cyclic stresses applied on structural systems and the terminologies used in fatigue resistant design are illustrated in this paper. The common form of presentation of fatigue data is by using the S-N curve, where the total cyclic stress （S） is plotted against the number of cycles to failure （N） in logarithmic scale. The point at which the S-N curve flattens off is called the ＂endurance limit＂. To carry out fatigue life predictions, a linear fatigue damage model is used in conjunction with the relevant S-N curve.

Evolution of Spiral Waves in Excitable Systems

Spiral waves, whose rotation center can be regarded as a point defect, widely exist in various two-dimensional excitable systems. In this paper, by making use of Duan＇s topological current theory, we obtain the charge density of spiral waves and the topological inner structure of its topological charge. The evolution of spiral wave is also studied from the topological properties of a two-dimensional vector field. The spiral waves are found generating or annihilating at the limit points and encountering, splitting, or merging at the bifurcation points of the two-dimensional vector field. Some applications of our theory are also discussed.

Design Drivers for Affordable and Sustainable Housing in Developing Countries

Current demand for housing worldwide has reached unprecedented levels due to factors such as human population growth, natural disasters and conflict. This is felt no more so than in developing countries which have experienced disproportionate levels of demand due to their innate vulnerability. Many current approaches to housing delivery in developing countries continue to utilize inappropriate construction methods and implementation procedures that are often problematic and unsustainable. As such affordability and sustainability are now vital considerations in the international development debate for housing the poor in developing countries in order to meet the long term sustainable development goals and needs of housing inhabitants. This paper utilized an extensive scoping study to examine the various facets impacting on design decision making relative to sustainable and affordable housing delivery in developing country contexts. Aspects of affordability, sustainability, design decision making, appropriate technology use, cultural awareness, as well as current barriers to affordable and sustainable construction in developing countries are examined in detail. Results highlighted the capability of indigenous knowledge, skills and materials as well as selected appropriate technology transfer and cultural awareness by foreign bodies can be utilized in innovative ways in addressing current housing needs in many developing country contexts.