焊接精英及上海造船行业优秀焊工表演赛圆满落幕

随着现代工业的不断发展，焊接逐渐成为国民经济发展的重要工艺。尤其在对焊接工艺要求较高的造船行业，焊工的技能越来越受到重视。     

色谱仪热导检测器电桥自动调衡的方案研究

本文针对色谱仪热导检测器电桥的工作特点。分析了用数字电位器替代机械电位器实现电桥自动调衡的两种方案，并根据较好的方案制作了热导检测器电桥的自动调衡电路，在实际应用中达到了理想的效果。     

基于Zigbee芯片的数据采集系统在钢丝绳无损检测中的应用

在一些恶劣的环境或者人难以到达环境下工作的钢丝绳,需要对它进行无损探伤检测和监测时,通过采集数据无线发送的方式是一种较好的选择,但是这种情况下也造成了更换电池的困难,于是对系统的功耗问题提出了更高的要求.介绍一种解决方案,利用Zigbee兼容的无线发射芯片和一款低功耗的MCU为核心组成数据采集以及无线传输的模块,详细介绍了所使用的一种简单的通信协议SMAC以及应用程序实现一个点对点的数据受控采集无线收发与数据波形显示的方案,包括上位机的监控程序.     

A band-gap voltage reference for interface circuit of microsensor

A high performance CMOS band-gap voltage reference circuit that can be used in interface integrated circuit of microsensor and compatible with 0. 6 μm ( double poly) mix process is proposed in this paper. The circuit can be employed in the range of 1. 8 - 8 V and carry out the first-order PTAT ( proportional to absolute temperature) temperature compensation. Through using a two-stage op-amp with a NMOS input pair as a negative feedback op-amp,the PSRR ( power supply rejection ratio) of the entire circuit is increased,and the temperature coefficient of reference voltage is decreased. Results from HSPICE simulation show that the PSRR is - 72. 76 dB in the condition of low-frequency,the temperature coefficient is 2. 4 × 10 -6 in the temperature range from - 10 ℃ to 90 ℃ and the power dissipation is only 14 μW when the supply voltage is 1. 8 V.     

我国粉煤灰综合利用现状与展望

粉煤灰是发电厂与各种燃煤锅炉排放的一种固体废弃物，据统计我国粉煤灰年排放量高达2亿t，且每年都在递增，是工业废渣中产量最大的一种废渣。不仅污染了环境还占用大量土地，造成的环境问题已相当严重。因此对粉煤灰治理是刻不容缓的，其综合利用可以化害为利，变废为宝，从而实现经济和社会的协调发展，具有十分重要的现实意义和深远的历史意义。     

计算机绘图与技术图样表达式（续二）

发明一种技术图样表达式。它用英文字母表示图形种类和尺寸要素，并用算术符号等字符表示图形和尺寸相互间的关系。用技术图样表达式可同时表示出图样的形状、大小、定位和公差、粗糙度等技术数据。图样表达式可作技术制图的尺寸标注，使图样大为简化；作计算机传输的信息，使计算机制图更为简易。     

Microstructure, ferroelectric, and piezoelectric properties of (1 − x − y)Bi0.5Na0.5TiO3-xBaTiO3-yBi0.5Ag0.5TiO3 lead-free ceramics

Lead-free (1 − x − y)Bi_0.5Na_0.5TiO₃-xBaTiO₃-yBi_0.5Ag_0.5TiO₃ (BNT-BT-BAT-x/y, x = 0-0.10, y = 0-0.075) piezoelectric ceramics were synthesized by conventional oxide-mixed method. The microstructure, ferroelectric, and piezoelectric properties of the ceramics were investigated. Results show that a morphotropic phase boundary (MPB) between rhombohedral and tetragonal phases of BNT-BT-BAT-x/0.04 ceramics is formed at x = 0.06-0.08. The addition of BAT has no obvious change on the crystal structure of BNT-BT ceramics while it causes the grain size of the ceramics to become more homogenous. Near the MPB, the ceramics with x = 0.06 and y = 0.05-0.06 possess optimum electrical properties: P_r ∼ 42.5 μC/cm², E_c ∼ 32.0 kV/cm, d₃₃ ∼ 172 pC/N, k_p ∼ 32.6%, and k_t ∼ 52.6%. The temperature dependences of k_p and polarization versus electric hysteresis loops reveal that the depolarization temperature (T_d) of BNT-BT-BAT-0.06/y ceramics decreases with increasing y. In addition, the polar and non-polar phases may coexist in the BNT-BT-BAT-x/y ceramics above T_d.