2 μm emission properties and hydroxy groups quenching of Tm3+ in germanate-tellurite glass

Tm³⁺ activated germanate-tellurite glasses with good thermal stability and anti-crystallization ability were prepared. Efficient 2 μm fluorescence was observed in the optimal concentration Tm³⁺ doped glass and the corresponding radiative properties were investigated. For Tm³⁺: ³F₄ → ³H₆ transition, high spontaneous radiative transition probability (260.75 s⁻¹) and large emission cross section (7.66 × 10⁻²¹ cm²) were obtained from the prepared glass. According to Dexter's and Forster's theory, energy transfer microscopic parameters were computed to elucidate the observed 2 μm emissions in detail. Besides, the effect of hydroxy groups quenching was also quantificationally investigated based on simplified rate equations. Results demonstrate that the optimal concentration Tm³⁺ doped germanate-tellurite glass possessing excellent spectroscopic properties might be an attractive candidate for 2 μm laser or amplifier.     

全自动引线键合机通信接口保护电路设计

基于TVS二极管的电气特性和全自动引线键合机的工作环境,设计了一种RS422通信接口的保护电路,并对限流电阻、接地连接、PCB布线和器件布局提出了一些原则性要求,最后对保护电路进行抗电子打火干扰实验。实验结果表明该保护电路的保护效果明显,可以避免接口电路被损坏。     

中温沥青密封承插口在6m焦炉的应用

介绍了上升管承插口采用中温沥青密封处理的新方法,已成功应用于4座6m焦炉,全年效益可达33万元,改善了作业环境,经济环保效益显著。     

锁口钢管桩围护仿真分析

以某深基坑开挖支护为工程背景,建立锁口钢管桩围护三维有限元模型。基于盾恩法确定了钢管桩嵌入深度,采用库仑经典土压力公式计算坑外主动土压力,应用＂m＂法计算坑底被动土压力。通过仿真计算得出各控制工况最大应力、变形的数值及发生位置,确定整个施工阶段的控制技术指标及参考值。     

A quartz-crystal-microbalance technique to investigate ion-induced erosion of fusion relevant surfaces

We describe a highly sensitive quartz-crystal-microbalance technique capable of determining erosion as well as implantation and retention rates for fusion relevant surfaces under ion bombardment. Total sputtering yields obtained with this technique for Ar ion impact on polycrystalline gold and tungsten surfaces are presented. The results compare well with existing experimental data as well as theoretical predictions and thus demonstrate the feasibility of the developed technique. Our setup is capable of detecting mass-changes as small as 10^−5 μg/s, which corresponds to a removal of only 10^−4 W monolayers/s.     

Structural design of current-mode biquad filters

This work describes how to generate and design a novel current-mode biquad filter model using tunable multiple-output operational transconductance amplifiers and grounded capacitors (MO-OTA-Cs) for synthesizing both transmission poles and zeros. Transfer functions of low-pass, band-pass, high-pass, notch and all-pass are realized based on the filter model. The theory focuses mainly on establishing a relationship between the cascaded MO-OTA-Cs and the multiple-loop feedback matrix, which makes the structural generation and design formulas. All the filter architectures contain only grounded capacitors, which can absorb parasitic capacitances and require smaller chip areas than floating ones. The simulation results are also presented to confirm the theoretical analysis.     

寬缝重力坝的经济性与实用性简析

本文从我国现行重力坝设计规范出发,结合我国宽缝重力坝的实际建设情况,采用结构优化设计方法,研究了在不同的地质条件、不同坝基防渗排水等条件下,实体重力坝与宽缝重力坝的工程量差别。在此基础上,结合考虑施工条件,本文作者对宽缝重力坝的经济性与实用性提出了新的看法.     

超硬铝合金LC9的超塑性效应

本文采用了简单的预处理工艺,开发超硬铝合金LC9的超塑性;并以等温拉伸试验和等温压缩试验相互对照、相互补充的试验方法,考察LC9的超塑性唯象学特性。结果表明,该合金的最高延伸率可达220％,m值为0.4,流动应力最低可达10MPa;最佳超塑性变形条件为:温度420℃,应变速率1.67×10~(-3)s~(-1)。     

One-dimensional tensile constitutive equation cannot be directly generalized to deal with two-dimensional bulging mechanical problems

Superplastic forming has been extensively applied to manufacture parts and components with complex shapes or high-precisions. However, superplastic formation is in multi-stress state. In a long time, uniaxial tensile constitutive equation has been directly generalized to deal with multi-stress state. Whether so doing is feasible or not needs to be proved in theory. This paper first summarizes the establishing processes of superplastic tensile and bulging constitutive equation with variable m, and, using the analytical expressions of equivalent stress a and equivalent strain rate ε of free bulge based on the fundamentals of continuum medium plastic mechanics, derives the analytical expressions of optimum loading rules for superplastic free bulge. By comparing the quantitative results on typical superplastic alloy ZnAI22, it is shown that one-dimensional tensile constitutive equations cannot be directly generalized to deal with two-dimensional bulging quantitative mechanical problems; only superplastic b     

基于CPLD的高速m序列码发生器的设计

从通信实验仪器设计的角度，介绍了一种高性价比的m序列发生器的分离电路实现方法。结构简单、电路可靠。