Novel fingerprinting mechanisms for indoor positioning

As wireless communications and microelectronic technology rapidly develop, diverse applications and services based on smart handheld devices have drawn the attention of researchers. The popularity of Indoor Location Based services and applications has also gradually increased. Therefore, how to improve indoor positioning accuracy becomes a very important issue. Although indoor positioning has been performed using various techniques in recent years, the computational complexity of ensuring positioning accuracy and positioning is an unsolved problem. Current indoor positioning systems typically use only the receiver or the transmitter to obtain the reference point data, and only the K‐Nearest Neighbors (KNN) or Trilateration algorithm is used to perform positioning. Therefore, positioning accuracy is limited by the use of reference point data from a single source and by the positioning algorithm used. The Novel Fingerprinting Mechanisms (NFM) indoor positioning system proposed in this study, however, uses both the receiver and transmitter to obtain positioning data and employs six positioning mechanisms to improve the current positioning accuracy. The experimental results show that the average error distance is 1.18 m in the NFM indoor positioning system. That is the system outperforms both KNN and Trilateration systems, which have average error distances of 1.35 m and 2.23 m, respectively. This study proves that the positioning accuracy is actually improved. Copyright © 2015 John Wiley & Sons, Ltd.     

彩信业务典型问题的分析及优化方法的探讨

主要以当前网络中增长较快的彩信业务存在的QoS低的问题为出发点,详细分析了彩信业务的关键流程及环节,确定了影响彩信业务QoS的关键因素。进一步介绍了彩信业务优化方法,进行了优化前后网络指标的对比。提出了终端规范性管理方式及智能支撑分析系统的建设思路。     

电源滤波器在医用电气设备中的应用

本文通过分析电磁干扰的主要类型以及其在医用电气设备中的危害,着重讨论将电源滤波器应用于医用电气设备中,以解决医用电气设备的电磁干扰现象。     

Design and application of a depletion-mode NJFET in a high-voltage BiCMOS process

A novel depletion-mode NJFET compatible high-voltage BiCMOS process is proposed and experimentally demonstrated with a four-branch 12-bit DAC(digital-to-analog converter).With this process,an NJFET with a pinch-off voltage ofabout-1.5 V and a breakdown voltage of about 16 V,an NLDDMOS(N-type lightly-dosed-drain in MOS) with a turn-on voltage of about 1.0 V and a breakdown voltage of about 35 V,and a Zener diode with a reverse voltage of about 5.6 V were obtained.Measurement results showed that the conver...     

逆合成孔径成像激光雷达低信噪比稀疏多孔径成像方法研究

受目标非合作特性的影响,逆合成孔径成像激光雷达(ISAIL)回波存在缺失;同时受大气衰减和自然背景光等因素的影响,ISAIL回波信号信噪比较低,因此,常规的稀疏多孔径成像方法不再适用。针对上述问题,该文提出了一种结合压缩感知(CS)和权矩阵的稀疏多孔径成像方法。首先,通过基于CS的稀疏多孔径成像方法对原始数据处理,得到目标像的支撑域;然后,据此建立权矩阵,优化采用CS重构时的代价函数,对稀疏多孔径ISAIL原始数据进行成像处理,利用不完整的回波信号获得高分辨目标像。此算法具有较好的抗噪能力。采用室内ISAIL系统实测数据验证了算法的有效性。     

分布式残余频偏信道中的Alamouti STBC-OFDM功率分配

在具有不同残余频偏的分布发射天线多径瑞利衰落信道中,该文使用Cholesky判决反馈检测的Alamouti STBC-OFDM链路,提出了一种抑制残余频偏影响的发射功率分配方法：以最小化残余频偏下链路的平均误比特率下界为准则,为发射天线分配功率。首先推导了残余频偏下链路的平均误比特率下界,然后给出了发射天线间最优功率分配因子的闭合解。仿真结果表明,与传统的假设频率理想同步的功率分配方法相比,在残余频偏对性能影响占主导作用的场景中,该文方法提升了链路性能,提升程度随着两根发射天线到接收机间平均信道功率增益之比的增加而增大。     

3D密码的不可能差分攻击

3D密码是在CANS2008上提出的一个新的分组密码算法,与以往的分组密码算法不同,它采用了3维结构。密码设计者给出了3D密码的一个5轮不可能差分并对6轮3D密码进行了不可能差分攻击。该文通过3D密码的结构特性找到了新的6轮不可能差分。基于新的不可能差分和3D密码的等价结构,可以对7轮和8轮3D密码进行有效的不可能差分攻击。此外,结合其密钥扩展规则,可以将攻击轮数提高至9轮。该文的攻击结果优于密码设计者的结果。     

Design of a Concentration Solar Thermoelectric Generator

Thermoelectric technology can be another direct way to convert solar radiation into electricity, using the Seebeck effect. Herein, a prototype concentration solar thermoelectric generator (CTG) and a discrete numerical model for the evaluation of the whole system are presented. The model takes into account the temperature dependence of the thermoelectric material properties by dividing the thermoelectric leg into finite elements and is proved to be more accurate for calculation of the conversion efficiency of the thermoelectric modules when large temperature gradients occur in the CTG system. Based on the best available properties of various bulk thermoelectric materials reported in the literature, the best possible performance of the CTG system is predicted, and the CTG system design, including the selection of the concentration ratio and the cooling method for different thermoelectric materials, are discussed in detail.     

轮古稠油降粘方法评价

考察了各种常规井筒降粘技术,如电加热降粘、掺稀油降粘、乳化降粘及降凝降粘剂降粘法,对轮古稠油井区稠油在中高含水期的降粘效果和适用性。结果表明,电加热降粘法不适宜于轮古稠油,乳化降粘法和降凝降粘剂降粘法对轮古稠油的适用性也不理想,掺稀油降粘法是一种适合于轮古中高含水期稠油降粘的技术。     

下二门油田核二段沉积微相粒度概率累积曲线

在岩心观测的基础上,利用主要取心井的粒度分析资料,系统总结了下二门油田核二段三角洲前缘-浊积体沉积不同微相的粒度概率累积曲线特征：水上分流河道微相为典型的两段式、一跳一悬加过渡式、复杂三段式和高斜多跳一悬加过渡;河口坝为高斜多跳一悬式、高斜一跳一悬加过渡和高斜两段式;远砂坝为两段式;前缘席状砂为高斜两段式和一跳一悬加过渡式;浊积体沉积为“宽缓上拱”式、“低斜多段”式和低斜一段式。