TRT入口方管道爆裂原因剖析

介绍了鞍钢7#高炉TRT装置入口方管道爆裂事故经过,进行了原因分析,并提出了解决措施。     

交流变频调速技术在二辊轧机压下系统中的应用

介绍一种采用变频调速技术控制的二辊轧机压下系统。该系统可控制轧机压下系统的速度在工艺要求的范围内无级可调，压下量以数字动态显示，控制准确、操作方便。文中对系统的组成及工作原理作了较详细的介绍。     

The Research of ST-OFDM in Physical Layer of IEEE 802.16a

This paper briefly introduces one of the three physical layer implementations of IEEE 802.16a~[1],WirelessMAN-OFDM PHY.Based on the implementation,the combination of Orthogonal Frequency Division Multiplexing(OFDM)and Space-Time Coding(STC)which is briefly called ST-OFDM in IEEE 802.16a,is investigated under thechannel provided in Ref.[2].Especially,this paper is focused on the influence of the optimal decision threshold on the sys-tern Bit-Error-Rate(BER)performance based on unequal probabilities of sources.The simulations show that when Signal-Noise-Ratio(SNR)is low the optimal decision threshold is obviously superior to the usual one;when SNR is high to someextent,such as 10 dB for 4QAM and 16 dB for 16QAM,we can use the usual decision threshold instead of the optimal     

Structural and magnetic properties of Co1+ySnyFe2-2y-xCrxO4 ferrite system

The samples of the series Co_1+ySn_yFe_{2- 2y- x}Cr_xO₄ ferrites with x = 0.0, 0.1, 0.2, 0.3, 0.4, 0.5 and y = 0.05, were prepared by the usual double sintering ceramic technique. The single- phase spinel structure of the samples was confirmed by using X- ray diffractometry technique. The lattice parameter ’a’ with an accuracy of ± 0.002 Å were determined using Bragg peaks of XRD pattern. The lattice parameter ’a’ decreases with concentration, x, which is due to the difference in the ionic radii of Cr³⁺ and Fe³⁺ ions. The X- ray intensity calculations were carried out in order to determine the possible cation distribution amongst tetrahedral (A) and octahedral [B] sites. The X- ray intensity calculations show Cr³⁺ ions occupying B site. The saturation magnetization, σ_s, and magneton number, n_B (the saturation magnetization per formula unit), measured at 300 K determined from high field hysteresis loop technique decrease with increase in concentration, x, suggesting a decrease in ferrimagnetic behaviour. Thermal variation of low field a.c. susceptibility measurements from room temperature to about 800 K exhibits almost normal ferrimagnetic behaviour and the Curie temperature, T_C determined from a.c. susceptibility data decreases with increase in x.

     

An adaptive non‐conforming finite‐element method for Reissner–Mindlin plates

Adaptive algorithms are important tools for efficient finite‐element mesh design. In this paper, an error controlled adaptive mesh‐refining algorithm is proposed for a non‐conforming low‐order finite‐element method for the Reissner–Mindlin plate model. The algorithm is controlled by a reliable and efficient residual‐based a posteriori error estimate, which is robust with respect to the plate's thickness. Numerical evidence for this and the efficiency of the new algorithm is provided in the sense that non‐optimal convergence rates are optimally improved in our numerical experiments. Copyright © 2003 John Wiley & Sons, Ltd.     

底部框剪砌体房屋空间弹塑性地震反应分析

本文提出了底部框剪砌体房屋这类上下混合承重结构体系的空间弹塑性地震反应时程分析方法。针对砌体结构和框架抗震墙结构截然不同的抗震性能，对上部砌体结构采用空间剪扭分析法，而对下部框架抗震墙结构采用空间协同分析法，建立了组合型串联刚片系振动模型。对单向和双向地震波输入结构层位移反应进行了比较。     

福州市档案馆消防设计

本文介绍了甲级档案馆消防设计,探讨了在我国目前档案馆建设中如何选择经济适用的灭火系统,并提出了有关设计规范间存在互为矛盾的问题。     

美国社区学院课程设置的特点

作为高等教育中最大的一个组成部分,美国社区学院为其经济和社会发展做出了巨大的贡献。美国社区学院卓越成就的取得与其独特的课程设置密切相关。尽管美国社区学院的类型多种多样,但从课程设置的指导思想上来说有其共性,它对我国高职院校课程的设置有一定的借鉴作用。     

Multi-step transformation in numerical renormalization group

We compute the temperature dependent magnetic susceptibility of the single-impurity, two-channel Anderson model with an alternative multi-step numerical renormalization-group transformation, previously applied only to the two-impurity single-channel Kondo model. Compared with the traditional transformation, the new procedure requires substantially less memory and computational time, and opens therefore perspectives for the application of the numerical renormalization-group procedure to more complex Hamiltonians.