一种新型的IGBT驱动保护电路

介绍一种新型的性能较完善的IGBT驱动保护电路。实验结果表明,该电路能快速、安全、可靠地实现保护功能。     

脱碳处理对Pt/WC复合材料催化性能的影响

采用溶胶-凝胶法,以钨酸钠为钨源、酚醛树脂为碳源合成碳化钨前驱体干凝胶,经原位碳化制备纳米碳化钨（WC）粉体,纳米WC粉体中的玻璃碳采用浓硝酸浸渍法脱除。在纳米WC粉料浆中以甲醛（HCHO）作为氯铂酸（H2PtCl6·6H2O）的还原剂,室温合成得到Pt/WC复合催化剂材料;以XRD、SEM、EDS等测试方法对样品的理化特性进行表征,并在酸性介质中采用循环伏安法测试材料的电化学催化活性。结果表明：相较于未经过脱碳处理的WC,经过浓硝酸脱碳处理后的Pt/WC电极催化材料的催化活性更好。经溶胶-凝胶法及原位碳化制备的纳米WC的颗粒径为20-80纳米,其本身具备较好的电催化活性。样品中残留的玻璃碳对WC具有包覆作用,会降低WC的电催化活性。采取浓硝酸脱碳的方式可有效脱除纳米WC粉体中的玻璃碳,发挥WC材料作为电极催化材料的电催化活性。     

添加微细铬铁粉对烧结钢摩擦磨损性能的影响

研究了加入不同含量的微细铬铁粉对烧结钢干摩擦磨损性能的影响,并借助于扫描电镜观察分析其磨损形貌,探讨摩擦磨损机制。研究结果表明:添加微细铬铁粉可改善烧结钢的强度、硬度和摩擦磨损性能,铬的质量分数为1.5%时,耐磨性最佳。磨损造成一定厚度的塑性变形,硬度较高的材料塑性变形层较薄。磨损早期,磨粒磨损是主导机制,磨损后期,由于塑性变形导致亚表层产生裂纹,进而发生的剥层磨损是主导磨损机制。     

A microcomputer-based system for processing 31-phosphorus nuclear magnetic resonance spectra from studies of cardiac metabolism in immature hearts

We designed an interactive microcomputer-based digital data processing system for analysis of 31-phosphorus nuclear magnetic resonance (31P-NMR) spectra from studies of cardiac metabolism in immature and neonatal hearts. This system included a digitizing tablet (Kurta Series Two), a microcomputer (IBM PC XT) and a graphics plotter (Hewlett-Packard 7470A) used in conjunction with a Nicolet 1280 NMR signal processing computer. We obtained 31P spectra from isolated perfused rabbit hearts with a Nicolet NT-200 4.7 Tesla superconducting NMR spectrometer operated in the pulsed Fourier transform mode. The small size of the hearts resulted in increased noise in spectra and demanded comparison of methods used to quantitate changes in inorganic phosphorus, phosphocreatine and ATP during ischemic stress. We performed microcomputer operations and interfacing functions with a software package written in BASIC. This system simplified documentation, data filing and statistical data processing. Our microcomputer system displayed and made hard copies of digitized spectra and results of analyses. Errors in data entry were rectified directly with this program. Consistent data reduction improved the precision of the physiological results and reduced the influence of noise on 31P spectra from neonatal hearts weighing about 0.5 g. The system flexibility extends its application to NMR spectra analysis for other in vivo organ systems, and signal processing in other biological research.     

交织码在无线通信可靠性中的应用研究

在对无线通信可靠性要求较高的系统中，如何保证信息的无误接收是关键。本文讨论了交织码的纠错原理，给出了具体的编码设计，对可靠性的提高进行了定性和定量的分析，并在工程中得到了验证。     

立井刚性罐道的测斜系统研究

介绍了基于虚拟仪器方案的立井罐道测斜系统,探讨了自适应消噪方法在其中的应用,并设计了验证消噪效果的模拟实验。     

Fabrication of Cu(In,Ga)Se2 thin films by ion beam sputtering deposition from a quaternary target at different substrate temperatures

Cu(In, Ga)Se₂ (CIGS) thin films were fabricated by ion beam sputtering deposition from a single quaternary target at different substrate temperatures (T _sub). The thin films were characterized with X-ray diffractometry, scanning electron microscopy, energy-dispersive X-ray spectroscopy and four-point probe technique to study the microstructures, surface morphology, composition and electrical properties, respectively. The results show that the films grown above 400?°C are of chalcopyrite structure. Cu(In_0.7Ga_0.3)Se₂ thin film was obtained when T _sub is 550?°C. The Cu and Se atomic percentage when T _sub is above 500?°C is higher than when T _sub is below 500?°C. With the increase in T _sub, the surfaces morphology of the films is denser and the resistivity of the films decreases.     

Image coding quality assessment using fuzzy integrals with a three-component image model

Based on importance measures and fuzzy integrals, a new assessment method for image coding quality is presented in this paper. The proposed assessment is based on two subevaluations. In the first subevaluation, errors on edges, textures, and flat regions are computed individually. The errors are then assessed using an assessment function. A global evaluation with Sugeno fuzzy integral is then obtained based on the importance measure of edge, texture, and flat region. In the second subevaluation, an importance measure is first established depending on the types of regions where errors occur, a subtle evaluation is then obtained using Sugeno fuzzy integral on all pixels of the image. A final evaluation is obtained based on the two subevaluations. Experimental results show that this new image quality assessment closely approximates human subjective tests such as mean opinion score with a high correlation coefficient of 0.963, which is a significant improvement over peak signal-to-noise ratio, picture quality scale, and weighted mean square error, three other image coding quality assessment methods, which have the correlation coefficients of 0.821, 0.875, and 0.716, respectively.     

目标与机会平衡规划法

提出一种目标与机会平衡规划法．基于待决策问题的有效决策前沿曲线形状的全局信息,通过权衡决策目标收益和实现机会两个因素的数值关系以及二者沿有效决策前沿曲线变化速度的对比关系,最大限度地提高决策效用．该方法能以更合理、更全面、更灵活的方式分析处理随机优化问题,有效解决期望值模型、机会约束规划法和相关机会规划法之间的矛盾．最后通过算例表明了所提出方法的主要特点和有效性．     

微机控制太阳能逆变电源

介绍了一种微机控制太阳能逆变电源,在这里微计算机按照给定的功率来控制逆变电源的输出电流,由于采用了锁相环技术,保证了逆变电源的输出与电网电压严格同步。控制器选用 Ｉｎｔｅｌ ８９Ｃ５１单片机,并在实验室中进行了实验,实验结果证明理论分析是正确的。