上海新国际博览中心

本文介绍了析国际博览中心项目的设计概念及工程概况。     

I/O-efficient join dependency testing,Loomis–Whitney join,and triangle enumeration

We revisit two fundamental problems in database theory. The join-dependency (JD) testing problem is to determine whether a given JD holds on a relation r. We prove that the problem is NP-hard even if the JD involves only relations each of which has only two attributes. The JD-existence testing problem is to determine if there exists any non-trivial JD satisfied by r. We present an I/O-efficient algorithm in the external memory model, which in fact settles the closely related Loomis–Whitney enumeration problem. As a side product, we solve the triangle enumeration problem with the optimal I/O-complexity, improving a recent result of Pagh and Silvestri in PODS'14.     

Failure analysis of threaded connections in large-scale steel tie rods

Steel tie rods are very important load-carrying components in applications where high levels of pre-stresses are required. The bearing capacity of a steel tie rod is determined not only by the strength of the rod body, but also by the strength of the threaded connection that resists force. Analysis of the strength of the threaded connection and determining the optimal number of turns of thread engagement is critical to ensure structural safety. This paper reports the results of full-scale tensile rupture experiments on two categories of large-scale steel tie rods provided by China JULI Corporation: (i) LG75-00 steel tie rods with triangle threaded connection, and (ii) LG100-00 steel tie rods with trapezoidal threaded connection. The full-scale tensile rupture experiments were carried out to test the maximum allowable axial working load under different numbers of turns of engaged threads. The results of these experiments suggest strong guidelines on the minimum number of turns of thread engagement for preventing the failure of thread teeth of steel tie rods in practical shear and bending applications.     

水轮机蜗壳的下料及成形

以钣金下料为基础,采用数学模型的方法,详细介绍水轮机蜗壳的展开下料及采用瓦片压制法压制时如何确定压形线,以确保产品质量符合设计要求.     

Strategies for industrial and technological development of Middle Eastern countries

Manufacturing sectors in Middle Eastern countries are facing many challenges when competing in local and world markets. These challenges include global and regional trade agreements, the creation of economic superpowers around the globe (North America, Europe, and East Asia) and higher standards to meet international quality requirements. Therefore, many countries in the region will have to rely on industrial and technological development in order ensure sustained economic development and face the above mentioned challenges. This paper discusses the important role of the Technology Triangle (partnership and cooperation between government, private sector, and education sector) in such a development. Issues that insure the effectiveness of the Technology Triangle are considered such as operational factors, financial responsibility, and implementation and monitoring. The paper also lists possible obstacles that can hinder industrial and technological development of Middle Eastern Countries. Finally, the paper will highlight the industrial and technological development of Lebanon after 15 years of civil strife. It reviews the impact of the reconstruction process on the development of a strong industry and Science and Technology institutions. Strategies are proposed for improvements.     

三角形柔性铰链的建模与分析

作为一种旋转单元,三角形柔性铰链可以组合为性能更加优良的柔性模块或柔性机构,如车轮形铰链、蝶形铰链等。建立准确的受力模型,分析其载荷—位移特性成为设计复杂铰链或机构的关键所在。基于近似的悬臂梁模型,建立三角形柔性铰链在同时受到弯矩、切向力和轴向力作用下精确的转角模型。得到未被近似的轴漂计算公式,并根据公式推导实用的轴漂模型。转角和轴漂模型都简洁地表征了载荷—位移关系,最后,通过有限元分析验证了所建立的模型的准确性。     

Evaluating Alloy Composition Using The Gibbs Triangle

Ingot quality is characterized by SPC evaluations; meaning Structure (S), Property (P), and Composition (C). Structure-property studies are classified as “sensitive” attributes while composition is considered to be an “insensitive” parameter. For example, it is common to hear the phrase that global composition is “insensitive” to structure and property values. For superalloys, structural analyses are applied using the scanning electron microscope (SEM) to determine both size, shape and distribution effects for the gamma prime phase. Examination of properties requires mechanical tests for strength, hardness, toughness and, so forth. However, for investigations on composition, the scientific community still depends on optical emission spectroscopy (OES) for measurements of global results using arc burns to represent bulk volume. This leads to the obvious question…. What needs to be done to better quantify the OES results? Further…. How can the controlling microconstituents of a superalloy be better related to the overall composition results for an improved qualification of ingots? This article addresses these needs and priorities. And, the said article is offered as a contribution to the sum of total knowledge.     

炮兵部队信息作战能力评估研究

在分析、确定炮兵部队信息作战能力评估指标体系基础上,运用三角白化权函数灰色理论并结合多层次分析法建立系统评估模型,从而为评估炮兵部队信息作战能力提供一种方法。该方法能够尽量消除因为评估的主观性所带来的偏差,客观地反映炮兵部队信息作战能力的真实情况,具有一定的参考价值。     

连续回转电液伺服马达压力冲击的理论分析

建立了对马达的密封腔内油液在排油过程的数学模型.采用MATLAB仿真软件求得其数值解,然后利用不同的转速对其进行仿真研究,得出在满足油液压力冲击最小的前提条件下的马达临界转速,并对密封腔内油液的压力梯度进行了仿真,总结了马达转速对油液压力梯度的影响.     

测量结果扩展不确定度模糊评定中最优水平的理论确定方法

针对测量结果扩展不确定度模糊评定中最优水平的主观确定问题，提出一种基于测量数据理论分布和模糊数学的理论确定方法。仿真结果表明，由该方法确定的最优水平所计算的扩展不确定度具有较高的计算精度。