Combining ideal beamforming and Alamouti space-time block codes

The simplest Alamouti space-time block code is coupled with a larger number of transmit antennas via ideal beamforming to achieve higher diversity gain. It is shown that the combined system can remain both full diversity and full code rate without orthogonality loss. Simulation results show a significant performance gain over the conventional space-time block codes.     

珠光体球化的分形研究

珠光体球化反映到金相上，是一种不规则图像的变化，并且具有分形的特征，可望用分形几何的方法来进行描述。以Cr-Mo钢的珠光体球化为例，用分形维数来描述珠光体球化程度；用小岛法对15CrMo钢的珠光体球化图谱进行了测量。实验表明，珠光体球化从1级到6级，其相应的分形维数范围为1.3156-1.9282。从电厂运行了10^5h的15CrMo钢管上取样，实测了该试样的珠光体球化等级，结果表明，以分形维数表示的球化程度与按图谱评定的球化等级完全吻合。     

海拉尔盆地的古河道砂体识别方法

本文基于海拉尔盆地贝尔凹陷西北部高精度三维地震资料,通过对时间域、频率域地震属性的分析,研究了河道砂体的变化及分布规律,总结出了一套利用时间域、频率域地震属性识别古河道的方法。其中对河道砂体较为敏感的沿层属性主要有均方根振幅、反射强度梯度、有效带宽及瞬时频度等。利用这种识别方法在该区找到水下分流河道砂体和河口坝砂体,为该区的岩性勘探部署提供了具体目标。     

炼油厂成品油罐区调度优化问题研究

研究了以集合论为基础的调度优化模型。给出了该离散型优化问题的求解算法。根据优化结果，在G2实时智能平台上开发了包含监视子系统和调度子系统的调度支持系统。在中国石化股份有限公司长岭分公司的试用结果表明，该调度系统可以提高炼油厂的生产效率，从而提高炼油厂的经济效益。     

地理信息系统在石油天然气长输管道中的应用

地理信息系统是利用现代计算机图形和数据库技术来处理地理空间及其相关数据的计算机系统,是融地理学、测量学、几何学、计算机科学和应用对象为一体的综合性高新技术。在石油天然气管道的管理向现代化、科学化和智能化方向发展的过程中,地理信息系统是有利的辅助手段之一。文章对地理信息系统发展、基本功能要求、建设内容及其在石油天然气管道中的应用进行了论述。     

PURE射孔技术在渤海油田试验应用分析

针对PURE射孔技术的工艺原理和技术特点进行阐述，分析了工具的结构原理和技术参数的选择，利用该射孔技术在试验井上进行了成功应用。现场实践证明，在低渗透油层使用该项技术能够达到很好的效果。该项技术具有安全、环保、高效等特点，能够满足一次多层射孔的大规模完井作业要求。     

On Finding the Multicast Protection Tree Considering SRLG in WDM Optical Networks

In this letter, a new sharing mechanism, SRLG sharing, is proposed, which allows the links of the same shared risk link group (SRLG) in a primary light tree to share protections in WDM optical networks. In previous studies, how to share spare resources with SRLG constraints has not been studied in multicast optical networks. In this letter, considering SRLG sharing, we propose a novel algorithm –multicast with SRLG sharing (MSS)– to establish a protection light tree. Finally, the algorithm MSS and the algorithm multicast with no SRLG sharing (MNSS) are compared through a simulation to show that our new sharing scheme of SRLG sharing is more efficient than that of no SRLG sharing in terms of spare resource utilization and blocking probability.     

Structured low-density parity-check codes

This article describes the different methods to design regular low density parity-check (LDPC) codes with large girth. In graph terms, this corresponds to designing bipartite undirected regular graphs with large girth. Large girth speeds the convergence of iterative decoding and improves the performance at least in the high SNR range, by slowing down the onsetting of the error floor. We reviewed several existing constructions from exhaustive search to highly structured designs based on Euclidean and projective finite geometries and combinatorial designs. We describe GB and TS LDPC codes and compared the BER performance with large girth to the BER performance of random codes. These studies confirm that in the high SNR regime these codes with high girth exhibit better BER performance. The regularity of the codes provides additional advantages that we did not explore in this article like the simplicity of their hardware implementation and fast encoding.     

子空间方法盲多用户检测技术分析与探索

着重分析了基于子空间跟踪的盲线性多用户检测算法 ,并对其内部算法模块进行了仿真比较 ,最后对算法性能改善方法提出了自己的新思路     

Measurement and numerical simulation of three‐dimensional fiber orientation states in injection‐molded short‐fiber‐reinforced plastics

To determine three‐dimensional fiber orientation states in injection‐molded short‐fiber composites, a confocal laser scanning microscope (CLSM) is used. Since the CLSM optically sections the specimen, more than two images of the cross sections on and below the surface of the composite can be obtained. Three‐dimensional fiber orientation states can be determined by using geometric parameters of fiber images obtained from two parallel cross sections. For experiments, carbon‐fiber‐reinforced polystyrene is examined by the CLSM and geometric parameters of fibers on each cross‐sectional plane are measured by an image analysis. In order to describe fiber orientation states compactly, orientation tensors are determined at different positions of the prepared specimen. Three‐dimensional orientation states are obtained without any difficulty by determining the out‐of‐plane angles utilizing fiber images on two parallel planes acquired by the CLSM. Orientation states are different at different positions and show the shell–core structure along the thickness of the specimen. Fiber orientation tensors are predicted by a numerical analysis and the numerically predicted orientation states show good agreement with measured ones. However, some differences are found at the end of cavity. They may result from the fountain flow effects, which are not considered in the numerical analysis. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 500–509, 2003