180m高钢筋混凝土烟囱爆破拆除

介绍了在复杂环境中，采用控制爆破技术，国内首次成功爆破拆除了180m高的钢筋混凝土烟囱，使国内烟囱的爆破高度跨上了一个新的台阶。该文为目前国内越来越多的高耸建筑物爆破拆除，提供了较高的参考价值。     

下穿铁路隧道长大管幕施工精度控制技术

厦门杏林大桥主体工程C标段,下穿铁路隧道部分洞顶覆土厚度1.6～2.5m,采用直径299mm管幕超前支护、浅埋暗挖的施工方法。其中,右线管幕最长为110m,管幕起着传递和扩散上部荷载的作用,是整个体系的关键。通过方案比选、机械选型和控制、定向钻进、锁扣改进等技术措施,成功完成了下穿铁路隧道的长大管幕施工。     

MICROSTRUCTURES AND PROPERTIES OF DZ40M Co-BASED SUPERALLOY AFTER LONG-TERM AGEING AT 850℃

ＩＮＴＲＯＤＵＣＴＩＯＮＤＺ４０ＭｉｓａｎｅｗｌｙｄｅｖｅｌｏｐｅｄｄｉｒｅｃｔｉｏｎａｌｙｓｏｌｉｄｉｆｉｅｄｃｏｂａｌｔｂａｓｅｄｓｕｐｅｒａｌｏｙｂａｓｅｄｏｎｃｏｎｖｅｎｔｉｏｎａｌＸ４０．ＣｏｍｐａｒｅｄｗｉｔｈＸ４０，ｉｔｈａｓａｈｉ...     

Spread spectrum directional modulation method based on the irrelevantly switched antenna for physical layer security transmission

In order to improve the security of wireless communication, a spread spectrum directional modulation method based on the irrelevantly switched antenna is presented. First, the security vulnerabilities of the existing spread spectrum directional modulation method are analyzed, indicating that the existing method has the risk of security leakage in some particular directions. Then by locating the security vulnerabilities of the existing method, a security-enhanced method is proposed by separating the antenna switching from the spectrum spreading to eliminate the security vulnerabilities. Finally, the physical layer security performance of two directional modulation methods is simulated, with the results showing that the proposed method has a better low detection performance and anti-jamming capability.     

Aerophilic Electrode with Cone Shape for Continuous Generation and Efficient Collection of H2 Bubbles

Hydrogen as a sustainable and clean energy source has attracted great attention with the increasing global energy crisis. However, sufficient production of hydrogen is seriously impeded by the adhesion of hydrogen bubble to electrodes. Efficient removal of hydrogen bubbles attached to the electrode can improve the efficiency of the hydrogen evolution reaction. Following this concept, numerous approaches to shorten the adhesion time of hydrogen bubbles on electrodes have been presented, such as ultrasonic treatment and electrode surface micro/nano‐modification. Almost all of the existing solutions are based on the instant and direct release of generated hydrogen bubbles into the electrolyte, which can be identified as “Releasing strategy” accordingly. In this contribution, an aerophilic electrode with cone shape is fabricated, from which the generated hydrogen bubbles can be timely removed through efficient and directional transportation (from tip to the base). Correspondingly, this approach is defined as “Transporting strategy”. Furthermore, integrating the base of electrode with a superaerophilic sponge, which possesses excellent properties of efficiently absorbing and releasing gas bubbles, can realize the collection of generated hydrogen. It is believed that the present approach can contribute to promising applications in water electrolysis and will offer inspiration for fabricating novel hydrogen collector.     

A pipelined database machine with efficient join operation

Abstract

Database management has become increasingly important in recent years. How to design an efficient database machine becomes an essential topic. This paper presents a database machine for supporting the primitive operations of a relational algebra. A hash‐sort‐merge strategy has been adopted to implement the join operation. A reconfigurable merger and bi‐directional zero‐time sorter have been employed in the database machine for flexibly sorting and merging various sizes of buckets. We compare the performance of our database machine with that of some other database machines. From our results, when the sizes of operand relations are large, our database machine is superior.     

Effects of high temperature annealing on the chemical homogeneity and Magnetostriction of Tb0.3Dy0.7Fe1.90 Intermetallic Compound

A rare earth-iron intermetallic compound Tb_0.3Dy_0.7Fe_1.90, also called Terfenol-D, has a gigantic room temperature magnetostriction at a relatively small magnetic field. In this study microsegregation of Tb and Dy in directionally solidified Terfenol-D was investigated. It was predicted from a calculated phase diagram and experimentally verified that Tb concentration at the center of the cell which solidified earlier was lower than that at the cell boundary. In order to homogenize this microsegregation, specimens were annealed at 1000°C for 40 hours, and various magnetic properties were measured as a function of applied field under uniaxial compressive stress in the range from 0.5 to 1.2 MPa. After the annealing, the maximum magnetostriction increased at a compressive stress below 9 MPa, magnetostrictive coefficient d₃₃ and magneto-elastic coupling coefficient k₃₃ increased, but permeability decreased. These results may be due to the reduction of magnetocrystalline energy which was locally very high before annealing due to microsegregation.     

电磁换向阀铁芯管开裂故障分析

针对某大型钢结构液压系统发生多起电磁换向阀铁芯管开裂故障,从阀件工作压力、服役环境和产品质量3个方面进行故障机制分析,通过平台动作过程中T口压力检测和铁芯管开裂特征材料失效分析,找出故障原因。结果表明:回油调速导致阀控箱内回油管实际压力大于阀件T口允许工作压力,并最终导致故障发生。     

65m高砖烟囱定向爆破

一座65m高的砖烟囱与砖窑连体，采用定向爆破技术，利用烟囱倒塌冲击作用将砖窑同时破除，介绍了爆破方案、爆破参数和施工方法，并对爆破效果进行了描述。     

Simulation of microstructural evolution in directional solidification of Ti-45at.%Al alloy using cellular automaton method

The microstructural evolution of Ti-45 at.%Al alloy during directional solidification was simulated by applying a solute diffusion controlled solidification model.The obtained results have shown that under high thermal gradients the stable primary spacing can be adjusted via branching or competitive growth.For dendritic structures formed under a high thermal gradient,the secondary dendrite arms are developed not very well in many cases due to the branching mechanism under a constrained dendritic growth cond...