Long-wavelength infrared photoinduced switching of a resonanttunneling diode using the intersubband transition

Voltage switching induced by long-wavelength infrared light from a CO₂ laser was observed using a double-barrier resonant tunneling diode (RTD) biased in the bistable region and the intersubband transition (IT) between the quantum confined states. Possible optoelectronic and all-optical switching applications involving hysteresis are proposed and discussed     

Rotative quadrature phase-shift keying

A rotative quadrature phase-shift keying (RQPSK) modulation scheme is proposed. By rotating the QPSK signal constellation by pi /2 either clockwise or anticlockwise during a symbol duration, the conventional QPSK scheme can be modified to transmit 3 bits per symbol to achieve both power and bandwidth efficiency.<>     

彩色多频同步显示器行激励级电路的倒推设计法（1）

行激励级电路的设计是完全为行输出级服务的,它实质上是行输出级电路设计的一个重要而不可分割的组成部分。因此行激励级电路的设计,自然采用了从显象管偏转线圈和行输出管到激励变压器和行激励级的倒推设计法。     

空调器用风冷冷凝器换热能力实验研究

实验测定了几种不同铜管、肋片组合的冷凝器在不同的风量和风机转速下的换热量，发现采用内螺纹铜管和迎风侧平片、背风侧冲缝片的冷凝器具有最优的换热性能。分析了多流路冷凝器中不同流路之间的制冷剂分配不均匀性和再热现象。     

长颗粒(柱状晶)Si3N4陶瓷的研究及进展

Si3N4陶瓷材料由于具有很好的高温性能及高的力学性能，而被广泛地用于结构陶瓷，如切削刀具等。然而，因为其对缺陷很敏感，故易受灾难性的失效。人们发展了多种Si3N4增韧陶瓷，其中自增韧由于一些优异的性能越来越受到人们的重视。在此文中，着重介绍了影响Si3N4陶瓷长颗粒(柱状晶)晶粒生成的因素，并介绍了国内外对长颗粒Si3N4晶的控制研究。     

五氧化二钽薄膜的制备及其I-U特性

本文利用脉冲直流反应磁控溅射的方法制备了五氧化二钽 (Ta2 O5)薄膜 ,俄歇电子能谱仪测试了薄膜的成分含量 ,椭偏仪测试了Ta2 O5薄膜的厚度和折射率 ,XRD分析了薄膜的晶体结构 ,并且分别研究了氧气含量、基底温度等成膜工艺对薄膜的影响。研究结果表明薄膜的成分主要是由氧气含量决定的。利用金属 绝缘体 (介质膜 ) 金属 (MIM)结构初步对Ta2 O5薄膜进行了电学性能的测试 :皮安电流电压源测试了薄膜的I U特性 ,制备出的薄膜折射率在 2 1～ 2 2 ,MIM的I U特性曲线显示了较好的对称性和低的漏电流密度     

网上查询选课系统及XML

从不同的角度来阐述新一代的Web语言－XML。     

Effect of magnesium content on the ageing behaviour of water-chilled Al-Si-Cu-Mg-Fe-Mn (380) alloy castings

A study of the effect of magnesium concentration on the ageing behaviour as measured by the hardness of 380 alloy was conducted for three levels of magnesium, namely 0.06 (base alloy), 0.33 and 0.5 wt%, for water-chilled castings (dendrite arm spacing ∼ 10–15 μm). Differential scanning calorimetry analysis of as-cast samples was carried out to determine the changes in the reactions of the phases obtained during alloy solidification, employing heating rates of 0.1 and 1.0°Cs⁻¹, up to approximately 700°C. Two heat treatments were applied to the as-cast alloys: T5 comprising ageing at 25 (room temperature), 155, 180, 200 and 220°C, for times up to 200 h, and T6 comprising solution heat treatment at 480 °C or 515°C for 8 h, followed by quenching in warm water at 60°C, followed by immediate artificial ageing at 155 or 180°C for varying times up to 100h. The results show that the higher hardness values obtained with T6 treatment can be explained by the excess precipitation of magnesium-containing phases in the as-solidified alloys. This precipitation could be eliminated under the high cooling-rate conditions prevalent in die-casting operations so that T5 treatment may be used to replace T6 treatment to produce the same hardness values. In addition, solution heat treatment in the low-temperature range (480–515°C) is adequate to produce the required changes in silicon morphology and dissolution of magnesium in the matrix. No significant difference in hardness behaviour was observed when the magnesium content was increased beyond 0.3 wt%.     

可编程光学二值双轨逻辑门

基于双轨逻辑,本文提出一种可级联的并行二值逻辑门。所有十六种二值逻辑运算可以采用偏振半波相延编程来实现。也提出了用电光晶体实现实时编程的方法。本文中给出了实验结果。