Optimal diagonal precoder for multiantenna communication systems

In this paper, we examine a multiantenna single-user wireless communication system fitted with a QR-based successive cancellation receiver (QR receiver). Initially, our consideration is confined to uncoded binary phase shift keying (BPSK) signals transmitted through independent and identically distributed (IID) Rayleigh fading channels and to the design of an optimum precoder for the transmitter. For minimum feeding back of the channel state information (CSI) to the transmitter from the receiver, we stipulate the precoder to be in the form of a power loading square diagonal matrix. We proceed to develop the theory for the design of this diagonal matrix based on the minimization of the lower bound of the average bit error rate (BER) of transmission. The design obtained provides substantially lower error rates than most of other existing schemes under the same environment. The corresponding gain in signal-to-noise ratio (SNR) can be several decibels. To further improve the performance, we extend the design to include an optimal detection order of the received bits using an iterative approach. This iterative process proves to have fast convergence and results in a design providing significant SNR gain. We also propose a subchannel dropping scheme for cases in which SNR is low, and when the minimum BER precoder is equipped with this scheme, its average performance can be substantially superior to the Vertical Bell Laboratories Layered Space-Time (V-BLAST) detection. We extend our design of the optimum precoder to quadrature amplitude modulation (QAM) modulation scheme and similar performance gain has been observed.     

Towards real-time business intelligence

Analysing data to predict market trends of products and services and to improve performances of enterprise business systems has always been part of running a competitive business. But it is becoming essential nowadays that not only is the analysis done on real-time data, but also actions in response to analysis results can be performed in real time and instantaneously change parameters of business processes. This paper discusses issues and problems of current business intelligence systems, and then outlines our vision of future real-time business intelligence. We present a list of emerging technologies which could contribute to the realisation of real-time business intelligence and some examples of applying them to improve BT’s systems and services.     

阿拉丁重构在华业务

重新认识中国市场时隔1个月以后,阿拉丁知识系统有限公司创始人、总裁、首席执行官Yanki Margalit携带几位高级助手再次踏上了中国的土地,Yanki Margalit一行2005年6月初在北京嘉里中心举办酒会,面对到会的国内诸位嘉宾和媒体记者,Yanki Margalit 筹躇满志地宣称,阿拉丁将总结以往的经验,以新的姿态重构在华业务。     

Preparation of BaMgAl10O17∶Eu2+ and Its Phase Behavior in Microemulsion System

BaMgAl10O17∶Eu2 (BAM) was prepared in the microemulsion system and its phase behavior was studied. There exists a small region in the reverse microemulsion system where the dispersed particles are of spherical form. In this way, BAM blue phosphor with good dispersion can be synthesized. The microemulsion phase diagrams of the pseudo-ternary system (Triton X-100/cosurfactant-oil-BAM brine) were first established intuitively by the dilution method. The microstructure of microemulsions was determined through eyeballing, conductance technique, and polar optical microscopy. Its phase behavior is affected by various factors, such as temperature (room temperature, 30, 40 ℃), oil, surfactants, and cosurfactants in microemulsions. According to the phase diagrams, the microemulsion system of Triton X-100/1-hexanol-hexane-BAM brine was chosen to prepare the precursor. The BAM phosphor can be obtained via sintering the precursor at a comparatively low temperature. The phosphors were characterized by XRD and vacuum ultraviolet (VUV) spectra.     

用于实时数据传输的滑动帧方法及其实现

根据某雷达系统对测量信号的快速传输要求,提出采用滑动帧的处理方法并在FPGA中实现,克服了传统帧处理难以满足快速传输要求的不足。阐述了滑动帧结构的构造思想,详述了滑动帧结构的特点及具体功能模块的实现。根据实际应用需求构造了滑动帧结构处理器,试验和应用结果表明设计可行有效,能充分满足实时数据传输的要求。     

Phase transition of LCP fluids confined in nanochannels through MD simulation

Manipulation of molecular orientation alignment in MCTLCPs (main-chain thermotropic liquid crystalline polymers) by pure shear at nano scale has been investigated for the first time using molecular dynamics (MD) simulation. Results indicate that high planar shear induces long-range uniform orientation ordering (liquid crystalline phase) of initially randomly orientated molecules of MCTLCP fluid confined in a nanochannel, which is confirmed by analyzing the orientation order parameter and the snapshots of MCTLCP liquid in a nanochannel under different shear rates. Insights into the origin of the phase transition phenomena are given at molecular level through investigating the thermodynamic density distribution of MCTLCP molecules in the nanochannel, suggesting that the energy shift due to a radical jump of system density affects both the magnitude and the orientation of the molecular ordering. Simulation results also show that there is a critical shear rate for transforming isotropic phase into liquid crystalline phase. The critical shear rate is dependent on the temperature of the MCTLCP system. Findings in this paper may present useful information for processing TLCP molecules at nano scale and the understanding of nanoflow.     

大浪淘沙——记北新集团的战略转型

企业成功的道路有许多条,成功的模式有很多种,但成功的企业都走出了一条适合自己企业的发展道路。北新集团亦是如此。多年来,面对风云变幻的市场环境,北新集团立足现实,着眼未来,兼顾历史,在坚持企业发展愿景和整体价值观的基础上,审时度势,精准出击,以无比的气魄完成了一次次堪称完美的战略转型,走出了一条虽有波折但却辉煌的发展道路。古人云:以史为鉴,可以知兴替。今天,在我们回眸北新20多年的发展历程时,除了自豪并骄傲于她的光荣外,我们更愿意从更大的时空范围,理性的眼光来审视北新历次成功转型背后的深刻原因和基本支撑,从中汲取智慧。