关于贺州市平桂管理区城投服务大厦施工质量与安全控制的几点体会

通过介绍广西壮族自治区贺州市平桂管理区城投服务大厦工程施工质量与安全控制,特别是基础工程、挡土墙工程、模板及脚手架工程、装饰装修工程等,指出一些工程施工质量与安全控制问题,并提出相应的控制措施,以供借鉴.     

Non-equilibrium extrapolation method in the lattice Boltzmann simulations of flows with curved boundaries (non-equilibrium extrapolation of LBM)

The fraction of the intersected link in fluid region is an important parameter in non-equilibrium extrapolation method (NEM) in the lattice Boltzmann study since the NEM adopts different extrapolation schemes when the fraction reaches a critical value. In the present study, effect of the critical value of the fraction on the lattice Boltzmann simulations of flows with curved boundaries is investigated. The flows around a single cylinder and two parallel-placed cylinders under uniform incoming streaming are chosen as typical cases. For these given flows, small critical value of the fraction causes the lattice Boltzmann simulation to suffer severe numerical instability. Moreover, the numerical results also show that large critical value of the fraction can result in more accurate numerical results for flows under large Reynolds numbers, while the numerical accuracy is almost independent of the critical value for flows under small Reynolds numbers.     

Anodization of nanoporous alumina on impurity-induced hemisphere curved surface of aluminum at room temperature

Nanoporous alumina which was produced by a conventional direct current anodization [DCA] process at low temperatures has received much attention in various applications such as nanomaterial synthesis, sensors, and photonics. In this article, we employed a newly developed hybrid pulse anodization [HPA] method to fabricate the nanoporous alumina on a flat and curved surface of an aluminum [Al] foil at room temperature [RT]. We fabricate the nanopores to grow on a hemisphere curved surface and characterize their behavior along the normal vectors of the hemisphere curve. In a conventional DCA approach, the structures of branched nanopores were grown on a photolithography-and-etched low-curvature curved surface with large interpore distances. However, a high-curvature hemisphere curved surface can be obtained by the HPA technique. Such a curved surface by HPA is intrinsically induced by the high-resistivity impurities in the aluminum foil and leads to branching and bending of nanopore growth via the electric field mechanism rather than the interpore distance in conventional approaches. It is noted that by the HPA technique, the Joule heat during the RT process has been significantly suppressed globally on the material, and nanopores have been grown along the normal vectors of a hemisphere curve. The curvature is much larger than that in other literatures due to different fabrication methods. In theory, the number of nanopores on the hemisphere surface is two times of the conventional flat plane, which is potentially useful for photocatalyst or other applications.PACS: 81.05.Rm; 81.07.-b; 82.45.Cc.     

Mechanism of photoconductivity gain and persistent photoconductivity for diamond photodetector

Photoconductivity gain (PG) and persistent photoconductivity (PPC) properties observed in diamond photodetector are theoretically explained by solving rate equations which describe capture and emission processes of photo-generated hole and electron through a boron acceptor and a hole trap in a diamond epilayer and a nitrogen donor in a diamond substrate. Formation of one-sided pn-junction between the epilayer and substrate and slow hole capture rate of acceptor and hole trap levels provide accumulation of photo-generated hole in the epilayer, which produces the PG larger than the ideal responsivity. The PPC current after turning off the deep ultraviolet light is interpreted as due to the slow hole capture rate of the acceptor and trap levels.     

Comparison of steam and autothermal reforming of methanol using a packed-bed low-cost copper catalyst

Small-scale reformers for hydrogen production via steam and autothermal reforming of hydrocarbon feedstocks can be a solution to the lack of hydrogen distribution infrastructure. A packed-bed reactor is one possible design for such purpose. However, the two reforming processes of steam and autothermal methods have different characteristics, thus they have different and often opposite design requirements. In implementing control strategy for small-scale reformers, understanding the overall chemical reactions and the reactor physical properties becomes essential. This paper presents some inherent features of a packed-bed reactor that can both improve and/or degrade the performance of a packed-bed reactor with both reforming modes.The high thermal resistance of the packed bed is disadvantageous to steam reforming (SR), but it is beneficial to the autothermal reforming (ATR) mode with appropriate reactor geometry. The low catalyst utilization in steam reforming can help to prevent the unconverted fuel leaving the reactor during transient by allowing briefly for higher reactant fuel flow rates. In this study, experiments were performed using three reactor geometries to illustrate these properties and a discussion is presented on how to take advantages of these properties in reactor design.     

Improving the accuracy of computer-aided radiographic weld inspection by feature selection

This paper presents new results of our continuous effort to develop a computer-aided radiographic weld inspection system. The focus of this study is on improving accuracy by feature selection. To this end, we propose two versions of ant colony optimization (ACO)-based algorithms for feature selection and show their effectiveness to improve the accuracy in detecting weld flaws and the accuracy in classifying weld flaw types. The performances of ACO-based methods are compared with that of no feature selection and that of sequential forward floating selection, which is a known good feature selection method. Four different classifiers, including nearest mean, k-nearest neighbor, fuzzy k-nearest neighbor, and center-based nearest neighbor, are employed to carry out the tasks of weld flaw identification and weld flaw type classification.     

轿车变速器可靠性寿命试验分析

本文简述了轿车变速器可靠性寿命试验的目的、方法和试验设计。并以一组轿车变速器可靠性寿命试验为例较详细地分析了试验数据的处理和可靠性的点估计和区间估计方法。     

GSM预付费业务的研究与实现

本文首先介绍了ＧＳＭ预付费业务在欧洲推出和应用的情况，该业务的功能需求、类型和特点，最后较详细地讲述了通过设立预付费业务处理中心和智能网两种业务实现方案。文章认为，第一种方案对现有ＧＳ网络影响较小，易于实现，但不能对用户帐目完全实行监控，功能单一，采用非标准协议，对其应用和发展产生限制。