试论建筑施工质量管理

提高建筑施工质量管理水平,是保证工程质量的重要手段。本文先点出加强建筑施工管理的重要性,再分析建筑施工质量管理过程中存在的问题,并提出相应的措施。     

Novel DTD and VAD assisted voice detection algorithm for VoIP systems

Echo cancellation plays an important role in current Internet protocol(IP) based voice interactive systems. Voice state detection is an essential part in echo cancellation. It mainly comprises two parts: double talk detection(DTD) and voice activity detection(VAD). DTD is used to detect doubletalk and prevent filter divergence in the presence of near-end speech, and VAD is used to determine the near-end voice activity and output silence indicator when near-end is silent. However, DTD straightforwardly proceeded may mistakenly declare double talk under double silent condition, coefficients update under the far-end silence condition may lead to filter divergence, and current VAD algorithms may misjudge the residual echo from the near end to be far-end voice. Therefore, a voice detection algorithm combining DTD and far-end VAD is proposed. DTD is implemented when VAD declares far-end speech, filtering and coefficients update will be halted when VAD declares far-end silence, and the far-end VAD adopted is multi-feature VAD based on short-time energy and correlation. The new algorithm can improve the accuracy of DTD, prevent filter divergence, and exclude the circumstance that far-end signal only contains residual echo from near end. Actual test results show that the voice state decision of the new algorithm is accurate, and the performance of echo cancellation is improved.     

论桥梁工程桥面裂缝原因及控制措施

随着社会的发展和进步，土力学理论以及科学技术的发展，各类工程建设项目在我国不断兴起，现代施工技术也应运而生。本文针对桥梁工程的桥面裂缝展开探讨，从而分析其形成原因，同时结合施工技术，就加强桥面的裂缝控制，不断采取有效措施。     

基于MAC序列的相位编码准连续波的研究与应用

本文在讨论用二相编码信号构成的准连续波的数学模型和模糊函数的基础上,引入新的二元序列--MAC序列,并对其产生以及自相关特性进行了详细研究。通过对采用该序列编码的准连续波信号的周期单码重复时和多码重复的模糊函数进行仿真,其结果具有很好的图钉状,即有较高的距离和多普勒分辨率;并将MAC序列的相位编码准连续波应用在波形设计中,脉压仿真结果表明相比较m序列码,MAC序列更适用于目标检测。     

精脱硫工序积碳与结焦的对策

介绍了甲醇生产中焦炉煤气精脱硫系统积碳与结焦的危害以及应对方法。通过设备改造及工艺调整等措施,减少各种杂质进入精脱硫系统,使加氢催化剂保持良好效果,实现设备长周期运行。     

浅谈建筑设计过程的质量控制与管理

在本文中，笔者首先详细阐述了建筑设计的质量控制与管理理念。并根据基本理念，提出了一系列完善质量控制和管理保证体系及运作方法，以期能够切实加强建筑设计的规范性作用。     

论述高层建筑玻璃幕墙设计方法

幕墙技术以其实用性和美观性在建筑工程中得到广泛的使用，本文首先分析了高层建筑玻璃幕墙设计时应该考虑的问题，接着重点分析了高层建筑玻璃幕墙设计，最后总结了保证建筑玻璃幕墙设计质量的措施，希望能够为高层建筑幕墙设计提供的借鉴。     

APPLICATION OF A FRACTIONAL-STEP SCHEME AND FINITE-VOLUME METHOD FOR SIMULATING FLOW PAST A SURFACE-MOUNTED MIXING TAB

The fractional-step scheme and finite-volume method are applied on a structured body-fitted grid to simulate the flow passing over a trapezoidal tab mounted on a flat plate. The implementation of boundary conditions on tab surfaces is greatly simplified with this grid system. Due to grid nonorthogonality, however, discretization of Navier-Stokes equations leads to linear systems with complicated coefficient matrices. For the problem size in this work, performance data indicate that parallel operations occupy about 98.38 % of the simulation, giving rise to a maximum parallel speedup of S p, max , 61.73. The flow passing over the trapezoidal tab is simulated at a Reynolds number Re = 600 based on the inlet free-stream velocity and the tab height, and the results are compared with a particle image velocimetry (PIV) measurement with the same parameters. The simulation successfully captures the vortex structures in the tab wake as observed in the experiments. Comparisons of the instantaneous flow patterns, the mean velocity, and second-order moments also show good agreement. The simulation and PIV experiment also produce a similar shear-stress distribution along the streamwise direction at the flat plate.     

A Piecewise Linear Interface-Capturing Volume-of-Fluid Method Based on Unstructured Grids

A piecewise linear interface calculation (PLIC) technique on triangular unstructured grids is proposed for the volume-of-fluid (VOF) method. For an interface cell, a straight line segment is set to approximate the actual interface by the gradient of the volume fraction function. Three gradient models are discussed, and the results show that the gradient model introduced from the moving particle semi-implicit method is of the highest accuracy. Mass flux is calculated in a Eulerian scheme depending on the relationship between the line segment and each boundary of the cell. It is proved that the combination of geometric and algebraic methods is most precise, because both geometric interface position and algebraic mass conservation are considered. Numerical experiments are conducted on unstructured grids generated by the traditional Delaunay triangulation method and the bubble packing method (BPM), which can produce much more regular triangular cells than the Delaunay method (see Wu and Chen, Numerical Heat Transfer B, vol. 58; pp. 343–369, 2010). Compared with Young's PLIC-VOF, our method is of satisfactory accuracy and sharpness. The deformation errors on the BPM grid are even smaller than those by the PLIC method on a structured grid. In addition, it is observed that the accuracy is higher on the unstructured grid, with better quality.     

推动科技进步 促进煤田地勘单位持续发展

推动科技进步，是煤田地勘单位贯彻落实科学发展观的需要，是调整经济结构、转变经济发展方式的先导，是增强经济发展后劲和市场竞争力的关键，是实现经济事业目标的动力源泉。