试论当代大学生IT素质的培养

从IT素质的涵义出发，论述了IT素质的涵盖内容、培养大学生IT素质的重要性以及IT素质的本质与特点．对高校树立人才培养新理念、培养优秀IT人才提出了有关建议及应对措施。     

装配式基坑支护结构在广州地区的应用

装配式基坑支护结构是将基坑支护的围护结构部分在工厂预制成型,再在现场与撑或锚装配组成的支护结构。工程实践表明,此项技术可有效节省工程投资、缩短工期。     

Effect of process parameters on impact strength of Al-7% Si alloy castings produced by VAEPC process

The castings produced by the evaporative pattern casting (EPC) process have blow holes. The blow holes in EPC castings are because of the non-escape of the gas produced as a result of burning of polystyrene pattern in the sand mold. To overcome the problem of blow holes, the EPC process is combined with the vacuum (V)- process. The vacuum applied to EPC mold draws the decomposed gases and improves the casting quality produced by the EPC process. The developed hybrid process has been termed as the vacuum assisted evaporative pattern casting (VAEPC) process. The objective of this paper to investigates the effect of process parameters, i.e, degree of vacuum, pouring temperature, grainfineness number, amplitude of vibration and time of vibration on the impact strength of Al-7% Si alloy castings in VAEPC process. In order to evaluate the effect of selected process parameters, the response surface methodology (RSM) is used to formulate a mathematical model which correlates the independent process parameters with the desired impact strength. The central composite rotatable design has been used to conduct the experiments. The results indicate that the impact strength decreases with increases in the grainfineness number and pouring temperature. Whereas, it has an inverse relationship with amplitude of vibration, time of vibration and degree of vacuum. The best value of impact strength (2.34 N/mm²) has been obtained at 400 mm Hg degree of vacuum imposed, 650°C as pouring temperature, 60 as sand grainfineness number, 460 μm as amplitude of vibration, and 70 s as time of vibration.     

河北省水安全现状分析及对策探讨

从水资源与水环境两方面分析了河北省水安全的现状,指出影响水安全的因素在于自然因素、人为因素及人与自然的不协调因素,并针对水安全问题可能引发的健康安全、粮食安全、经济安全、生态环境安全进行了讨论,最后探讨了解决河北省水安全问题的对策。     

Time Characterization of High Density Gas Jet from a Pulsed Supersonic Nozzle via Laser Produced Plasma

A high-density gas jet supersonic nozzle is reported in this paper. The jitter and actuation time of the nozzle is determined by the pin discharge and laser spark radiation respectively. The jitter time of the nozzle is within 10μs with the backing pressure as high as 25 bar. With a nanosecond laser pulse focused on the gas jet about 1 mm below the nozzle, the actuation time is calculated to be about 15 ms by detecting the laser produced spark radiation, which reveals the existence of the gas jet and the relative gas density evolving with time. Consequently the gas density is estimated to be well above 10^19 cm^-3, compared with theoretical simulations from the nozzle parameters.     

合金钢连铸机生产工艺分析及实践

对新钢特殊钢有限责任公司整个合金钢连铸机的生产工艺进行了分析，提出了提高钢水质量和优化连铸工艺参数的有效措施，使铸坯的质量得到了有效控制和改善。     

透反液晶显示器

兼有透射型和反射型液晶显示优点的透反液晶显示可工作于透射和反射两种显示模式，它将广泛应用于手机、PDA等通讯领域。透反液晶显示可分为单盒厚和双盒厚两大类。又可分为扭曲型和非扭曲型两种。为了研制出高性能透反液晶显示器，需解决透反两个显示区的响应时间、光效率、色饱和度的差异以及视角等问题。文中介绍了Sharp公司开发的2种基本的透反液晶显示。以及3种新近开发的高性能透反液晶显示。随着应用市场的扩大和技术的进步，透反液晶显示将会进一步得到发展。     

Electrochemical C-V Characteristics and Photoluminescence of a-C∶N Films

Amorphous carbon (a-C) films and amorphous carbon films incorporating with the nitrogen (a-C∶N) were deposited on silicon substrates in a radio-frequency driven plasma enhanced chemical vapour deposition system, while the surface electrical properties of films were investigated by electrochemical capacitance-voltage measurements. It was examined the effect of the interface defects on the properties and deduced that the conducting type of a-C∶N films was n-type. Subsequently, a comparative studies of a-C and a-C∶N films were performed by photoluminescence spectra depending on the temperature. With the decrease of the temperature, the main band with peak energy of 2.48 eV in the a-C∶N films was more intense compared with the other three bands caused by amorphous C in the a-C films.     

Similarity retrieval of iconic image database

The perception of spatial relationships among objects in a picture is one of the important selection criteria to discriminate and retrieve the images in an iconic image database system. The data structure called 2D string, proposed by Chang et al., is adopted to represent symbolic pictures. The 2D string preserves the objects' spatial knowledge embedded in images. Since spatial relationship is a fuzzy concept, the capability of similarity retrieval for the retrieval by subpicture is essential. In this paper, similarity measure based on 2D string longest common subsequence is defined. The algorithm for similarity retrieval is also proposed. Similarity retrieval provides the iconic image database with the distinguishing function different from a conventional database.