HIGH RESOLUTION REAL-TIME MEDICAL IMAGING BASED ON PARALLEL BEAMFORMING TECHNIQUE

Improvement of frame-rate is very important for high quality ultrasound imaging of fast-moving structures.It is also one of the key technologies of Three-Dimension (3-D) real-time medical imaging.In th...     

利用复制SIM卡及网络漏洞进行欺诈的行为探析与对策研究

近年来,随着人们对移动通信业务的各种需求与日俱增,移动通信市场规模的不断扩大.在巨大的经济利益的驱使下,出现了大量利用移动通信网络的缺陷进行话费欺诈的现象,使电信运营商蒙受了巨大的经济损失.本文将对SIM卡复制的原理及利用复制SIM卡发送垃圾短信等话费欺诈行为进行深入的分析,提出针对此类问题的防范措施,以期提高移动通信...     

“数字图像处理”课程教学实践与探讨

数字图像处理是信息类专业重要的本科专业课程之一。在为我院本科生讲授的数字图像处理课程实践中,我们尝试融合多种教学手段,提升课程教学效果。本文结合前期教学实践,从可视化教学手段、知识关联比较、理论结合实践、双语教改和教学大纲改进等方面介绍在该课程教学方面的一些探索和体会。     

Use of 2, 3-Butanedione Monoxime for Homogeneous Precipitation of Nickel (II)

Abstract

The solid monoxime of 2, 3-butanedione is a more convenient material than liquid dione for the homogenous generation of DMG. 2, 3-butanedione dioxime. Determinations of Ni in steels and in pure Ni(II) solutions have shown the optimum pH and order of adding reagents. Gravimetric and/or an EDTA titrimetric finish are possible for a method of reliability within ± 0.2 mg of Ni in 50–150 mg Ni. The solid has the same character and filterability as that from the 1960 dione method of Salesin and Gordon¹.     

A novel clipping technique for filtering FM signals embedded in intensive noise

A novel adaptive clipping technique for filtering a constant amplitude frequency modulated (FM) signal embedded in non-Gaussian noise is proposed. It is based on the analysis and processing of the estimate of probability density function of a FM signal realization. As a result, modifications of two robust estimators of FM signal amplitude are proposed. It is shown that these estimators can be used for Gaussian and non-Gaussian heavy-tail environments. The proposed clipping technique can exploit one or another obtained robust estimate of the signal amplitude for adaptive setting a threshold. Analysis of signal estimate accuracy for different noise environments is carried out. Comparative analysis of the obtained methods and known approaches based on scanning window nonlinear filtering and optimal robust L-DFT form is performed. It is demonstrated that the usage of clipping-based technique leads to the considerable improvement of the FM signal filtering efficiency in comparison to the aforementioned known approaches for different noise environments and a wide range of input SNR values.     

基于MIMO-OFDM系统的盲源分离算法研究

为了实现使用OFDM调制的MIMO系统的盲源分离问题,提出了在接收端使用Nyquist频率对接收到的信号进行采样的,从而将原始的MIMO-OFDM系统盲源分离问题转变为N组的独立分量分离的问题.通过将FastICA算法扩展到复数域,在频域中对每一组相同子载波上的信号进行独立分量分析,最终实现信号的盲分离.仿真实验获得的结果证实了该方案具有良好的恢复效果,且算法收敛的迭代次数只需要8～10次.     

A new wideband regulated cascode amplifier with improved performance and its application

This paper presents a new high frequency Regulated Cascode (RGC) amplifier with improved performance. The split-length compensation technique is used to increase both the bandwidth and output impedance, and decrease the input impedance of the conventional RGC. The bandwidth of the proposed RGC amplifier is 5.81 GHz, which is about 2.7 GHz larger than that of simple one. The improved performance of the introduced circuit is achieved with no additional passive element and DC power dissipation. In the paper, output impedance and bandwidth of the proposed circuit are derived by using small signal analysis and have also been compared with the traditional one. In addition, a wideband high performance current mirror is designed in the work as an application of the proposed RGC structure. The bandwidth extension ratio (BWER) of the modified wideband current mirror is 1.37. The proposed circuits are designed by using TSMC 0.18 µm CMOS process and BSIM3 Level 49 device model. The circuits are simulated on Spectre simulator of Cadence to validate the analytical results obtained in the paper.     

自适应阵列抗干扰性能的解析定量分析

自适应阵列抗干扰性能常用输出信干噪比(Signal-to-Interference and Noise Ratio,SINR)损失、抗干扰改善因子(ECCM Improvement Factor,EIF)等来衡量,但目前尚缺乏解析的定量分析.为此,采用归纳法理论推导了均匀线阵条件下输出SINR损失、EIF等指标的解析表达式,定量获取了自适应阵列抗干扰性能.仿真实验验证了理论分析结果的有效性及快拍数对自适应阵列抗干扰性能的影响.     

ZIF-67 derived carbon wrapped discontinuous CoxP nanotube as anode material in high-performance Li-ion battery

Transition metal phosphides (TMPs) are prospective anode materials for lithium-ion batteries (LIBs) due to their high theoretical capacities and low redox voltages. Herein, we report a template directing method to develop a tube-sheath hybrid composing of cobalt phosphide particles encapsulated in metal organic frameworks (MOFs) derived N-doped carbon sheaths (Co_xP@NC). The utilization of directing template leads to a homogenous distribution of the subsequently formed cobalt phosphide particles, restrains the aggregation of cobalt phosphides, and thus results in the superb rate capability and cyclability. Contributable to the integrated merits of the interior downsized cobalt phosphide particles and the outer ZIF-67 derived porous carbon sheath, the volume expansion during cycling is effectively suppressed. The Co_xP@NC hybrid shows superb electrochemical performance as anode material for LIB, with good reversible capacity of 928 mAh·g^?1 after 100 cycles at 0.1 A g^?1, and high stability of 526 mAh·g^?1 after 600 cycles at 1.0 A g^?1. This work provides a route for rational design of MOF derived carbon-based anode material for LIB, which could also be applied as a promising platform in diverse field.     

BIDIRECTIONAL TRANSMISSION OF ADDRESSED AUDIO SIGNAL THROUGH GI MULTIMODE OPTICAL FIBRES

This paper describes two types of bidirectional addressed audio signal transmission systems where the square-wave frequency modulation (SWFM) and intensity modulation (IM) are used to obtain the optical SWFM signals generated from LEDs at 850 nm. The first one is an addressed audio signal transmission network of tree structure. The sender and auxiliary receiver in the centre are connected to four terminals, each consisting of a receiver and an auxiliary sender, through pairs of optical fibres and an optical splitter used as an optical signal distributor. The second one is a new type of full-duplex one-to-one communication system. The sender and auxiliary receiver in one terminal are connected to the receiver and auxiliary sender in the other terminal through an optical fibre and a pair of directional couplers. Although LEDs in the second system deliver optical SWFM signals at the same wavelength of 850 nm at the same time, the communications are satisfactory because there is no interference from one LED to the other. In both the first and second experimental systems, the audio signal, address, and SWFM carrier occupy 10 Hz to 20 kHz, 65 kHz to 710 kHz, and 6 MHz, respectively. The SNR and distortion were 62 dB and 0.4 per cent, respectively.