A Novel M‐ary Code‐Selected Direct Sequence BPAM UWB Communication System

In this letter, a novel M‐ary code‐selected direct sequence (DS) ultra‐wideband (UWB) communication system is presented. Our purpose is to achieve a high data rate by an M‐ary code‐selected direct sequence bipolar pulse amplitude modulation (MCSDS‐BPAM) scheme. In this system, a particular DS code sequence is selected by the log₂M/2 bits from the DS gold code set. This scheme can accomplish both a high data rate without increasing the system bandwidth or changing the pulse shape and improve the BER with an increase of modulation level M even at a lower signal‐to‐noise ratio (SNR). The receiver signal processing algorithm is given for an MCSDS‐BPAM UWB system over an ideal AWGN channel and correlation receivers.     

High Durable,Biocompatible, and Flexible Piezoelectric Pulse Sensor Using Single‐Crystalline III‐N Thin Film

Flexible pulse sensors that can detect subtle skin surface deformation caused by arterial pulses are key components for developing non‐invasive continuous pulse waveform monitoring systems that provide vital health status parameters. Piezoelectric pulse sensors (PPSs) offer a promising solution for flexible pulse sensors due to their relatively high sensitivity and stability, and low power consumption, when compared with conventional active pulse sensors. However, the reported high‐performance PPSs contain toxic lead, which limits their practical applications. In this study, a highly sensitive and flexible PPS that detects surface deflections on the micrometer scale is fabricated with single‐crystalline group III‐nitride thin film. This biocompatible flexible PPS is sensitive enough to detect pulse waveform with detailed characteristic peaks from most arterial pulse sites when attached to the skin surface without applying external pressure. Useful physiological parameters such as the pulse rate, artery augmentation index, and pulse wave velocity can be drawn from the as‐acquired pulse waveforms. The flexible PPS can also be used to continuously monitor the arterial pulse waveform.     

Self‐Powered Electrochemical Synthesis of Polypyrrole from the Pulsed Output of a Triboelectric Nanogenerator as a Sustainable Energy System

Triboelectric nanogenerators (TENG) are able to convert mechanical energy into electricity. In this work, a self‐powered electrochemical synthesis circle is designed, in which the electrode material of the TENG, polypyrrole (PPy), is prepared by the pulse output of the PPy‐based TENG itself. The TENG based on PPy from self‐powered synthesis (SPSPPy) presents a competitive performance compared to those made from commercial pulse sources. A supercapacitor that is fabricated from SPSPPy has a far superior performance than that synthesized by the conventional galvanostatic method. Furthermore, a self‐charging power system that integrates a TENG and a supercapacitor is demonstrated to drive an electronic device sustainably. Moreover, the polymerization efficiency is optimized in TENG‐based electrochemical synthesis because its high voltage can sustain multiple reactors simultaneously. Its upper limit is theoretically analyzed for optimal energy utility, and a maximum number of 39 reactors can be powered experimentally. Hence, TENG is validated as an effective pulse generator for the synthesis of PPy as well as other electrochemical technology, and this work greatly improves the understandings of TENG‐based self‐powered electrochemical systems.     

基于STC89C52便携脉搏测量仪的研制

现在的人们越来越注重自身健康,特别是老年人,他们需要定期体检,但是在医疗水平落后的区域定期体检很难实现。因此文中设计了一款以STC89C52单片机为控制核心,采用HKG-07A红外式脉搏传感器采集数据,通过A／D转换器,送给液晶显示测量结果。经过与医用脉搏测量仪比较,系统具有精度高、性能稳定、反应迅速、性价比高的特点,而且结构简单、使用简洁方便,具有很高的市场价值。     

Pulse shaping for cognitive ultra‐wideband communications

Cognitive ultra‐wideband (C‐UWB) systems have recently received much attention because the huge bandwidth of ultra‐wideband (UWB) systems can better exploit the advantages of cognitive radio (CR) systems. Dynamic spectrum access (DSA) is a key technique in CR systems to implement dynamic spectrum change and can be easily implemented by changing the transmitted pulse shape in a C‐UWB communication system. In this paper, we propose an orthogonal expansion based pulse shaping method to implement DSA and to compensate for antenna distortion, which uses the orthogonal Hermite functions as the orthogonal basis. In order to eliminate the direct current (DC) component existing in even orthogonal Hermite functions and to reduce the computational complexity, two modified methods and a simplification procedure are also proposed. Our results indicate that the proposed orthogonal expansion based pulse shaping methods have a much lower computational complexity than the semi‐definite programming (SDP) method, while achieving a high power efficiency. Furthermore, we demonstrate that the distortion caused by the antenna effects can also be compensated during the pulse shaping process and a better signal‐to‐noise ratio (SNR) can thus be achieved. Therefore, the proposed method is very suitable for practical application in C‐UWB communications, in which the spectrum environment changes rapidly. Copyright © 2009 John Wiley & Sons, Ltd.     

A Discrete‐Amplitude Pulse Width Modulation for a High‐Efficiency Linear Power Amplifier

A new discrete‐amplitude pulse width modulation (DAPWM) scheme for a high‐efficiency linear power amplifier is proposed. A radio frequency (RF) input signal is divided into an envelope and a phase modulated carrier. The low‐frequency envelope is modulated so that it can be represented by a pulse whose area is proportional to its amplitude. The modulated pulse has at least two different pulse amplitude levels in order that the duty ratios of the pulse are kept large for small input. Then, an RF pulse train is generated by mixing the modulated envelope with the phase modulated carrier. The RF pulse train is amplified by a switching‐mode power amplifier, and the original RF input signal is restored by a band pass filter. Because duty ratios of the RF pulse train are kept large in spite of a small input envelope, the DAPWM technique can reduce loss from harmonic components. Furthermore, it reduces filtering efforts required to suppress harmonic components. Simulations show that the overall efficiency of the pulsed power amplifier with DAPWM is about 60.3% for a mobile WiMax signal. This is approximately a 73% increase compared to a pulsed power amplifier with PWM.     

Multi‐carrier platform for wireless communications. Part 1: High‐performance,high‐throughput TDMA and DS‐CDMA via multi‐carrier implementations

Multi‐carrier technologies in general, and OFDM and MC‐CDMA in particular, are quickly becoming an integral part of the wireless landscape. In this first of a two‐part survey, the authors present the innovative transmit/receive multi‐carrier implementation of TDMA and DS‐CDMA systems. Specifically, at the transmit side, the pulse shape (in TDMA) and the chip shape (in DS‐CDMA) corresponds to a linear combining of in‐phase harmonics (called a CI signal). At the receiver side, traditional time‐domain processing (equalization in TDMA and RAKE reception in DS‐CDMA) is replaced by innovative frequency based processing. Here, receivers decompose pulse (or chip) shapes into carrier subcomponents and recombine these in a manner achieving both high frequency diversity gain and low MAI. The resulting system outperforms traditional TDMA and DS‐CDMA systems by 10–14 dB at typical BERs, and, by application of pseudo‐orthogonal pulse shapes (chip shapes), is able to double system throughput while maintaining performance gains of up to 8 dB. Copyright © 2002 John Wiley & Sons, Ltd.     

Modeling and Simulation of New Encoding Schemes for High‐Speed UHF RFID Communication

In this paper, we present novel high‐speed transmission schemes for high‐speed ultra‐high frequency (UHF) radio‐frequency identification communication. For high‐speed communication, tags communicate with a reader using a high‐speed Miller (HS‐Miller) encoding and multiple antennas, and a reader communicates with tags using extended pulse‐interval encoding (E‐PIE). E‐PIE can provide up to a two‐fold faster data rate than conventional pulse‐interval encoding. Using HS‐Miller encoding and orthogonal multiplexing techniques, tags can achieve a two‐ to three‐fold faster data rate than Miller encoding without degrading the demodulation performance at a reader. To verify the proposed transmission scheme, the MATLAB/Simulink model for high‐speed backscatter based on an HS‐Miller modulated subcarrier has been designed and simulated. The simulation results show that the proposed transmission scheme can achieve more than a 3 dB higher BER performance in comparison to a Miller modulated subcarrier.     

Bio‐inspired Photoelectric Conversion Based on Smart‐Gating Nanochannels

Inspired by the light‐driven, cross‐membrane proton pump of biological systems, a photoelectric conversion system based on a smart‐gating, proton‐driven nanochannel is constructed. In this system, solar energy is the only source of cross‐membrane proton motive force that induces a diffusion potential and photocurrent flowing through the external circuit. Although the obtained photoelectric conversion performance is lower than that of conventional solid photovoltaic devices, it is believed that higher efficiencies can be generated by enhancing the protonation capacity of the photo‐acid molecules, optimizing the membrane, and synthesizing high‐performance photosensitive molecules. This type of facile and environmentally friendly photoelectric conversion has potential applications for future energy demands such as the production of power for in vivo medical devices.     

Large‐Scale and Washable Smart Textiles Based on Triboelectric Nanogenerator Arrays for Self‐Powered Sleeping Monitoring

Sleeping disorder is a major health threatening in high‐pace modern society. Characterizing sleep behavior with pressure‐sensitive, simple fabrication, and decent washability still remains a challenge and highly desired. Here, a pressure‐sensitive, large‐scale, and washable smart textile is reported based on triboelectric nanogenerator (TENG) array as bedsheet for real‐time and self‐powered sleep behavior monitoring. Fabricated by conductive fibers and elastomeric materials with a wave structure, the TENG units exhibit desirable features including high sensitivity, fast response time, durability, and water resistance, and are interconnected together, forming a pressure sensor array. Furthermore, highly integrated data acquisition, processing, and wireless transmission system is established and equipped with the sensor array to realize real‐time sleep behavior monitoring and sleep quality evaluation. Moreover, the smart textile can further serve as a self‐powered warning system in the case of an aged nonhospitalized patients falling down from the bed, which will immediately inform the medical staff. This work not only paves a new way for real‐time noninvasive sleep monitoring, but also presents a new perspective for the practical applications of remote clinical medical service.     

Performance enhancement of overall LEO/MEO intersatellite optical wireless communication systems

This paper has deeply investigated the performance signature of modulation techniques based low earth orbit (LEO)/medium earth orbit (MEO) intersatellite optical wireless communication systems for possible communication coverage distance of 20 000 km with possible transmission bit rate of 0.5 Tb/s. These modulation techniques that are namely multilevel quadrature amplitude modulation (M‐QAM), multilevel phase shift keying (N‐PSK), multilevel pulse amplitude modulation (H‐PAM), and finally multilevel differential phase shift keying (L‐DPSK) based on different electrical pulse generators for upgrading LEO/MEO intersatellite link operation efficiency. These pulse generators that are namely Gaussian pulse generator (GPG), hyperbolic secant pulse generator (HSPG), and raised cosine pulse generator (RCPG). The variations of maximum Q‐factor, minimum bit error rate (BER), and optical signal‐to‐noise ratio in relation to number of bits/symbol for different modulation techniques can be deeply studied in the presence of vertical cavity surface emitting laser (VCSEL). This study is done with using Optiwave system simulation version 7 for different modulation techniques, and all figures are sketched with using wizard Excel sheet set up. It is observed that maximum Q‐factor and minimum BER are optimized with using GPG and 8‐PAM, as well as 4‐DPSK with both HSPG and RCPG.     

低频/甚低频电磁脉冲测量系统研究

为了准确地测量电磁脉冲（electromagnetic pulse,EMP）的波形,开展低频/甚低频（low-frequency/very low-frequency,LF/VLF）EMP的形成和传播机理研究,识别不同EMP的特征,并以此为依据来识别、确认雷电及核爆炸等现象,提出了一种高分辨率的EMP原始波形测量系统方案,同时针对LF/VLF这一较低的频段提出了一套有效的系统标校方法,实现了对EMP的连续、准确测量和快速有效判别,并能通过网络实时上传数据.系统采用正交环磁场天线和平板电容电场天线实现信号的接收,设计了低噪声高保真的信道调理电路和高速数据采集电路来实现信号的采集,利用高精度的授时模块为EMP信号标记时间戳,最后结合多点监测波形实现EMP定位估计.实测结果表明:该系统能够给出高分辨率、高精度的LF/VLF EMP波形;利用该系统组网可以实现远距离EMP源的定位,定位精度与目前近距离的定位手段相当.通过长期的运行,验证了该系统具有高可靠、低失真、判别准确、实时性强等特点.     

High‐capacity soliton transmission for indoor and outdoor communications using integrated ring resonators

A system consisting of a series of microring resonators, incorporating an add/drop system, is presented in order to create ultra‐short spatial and temporal single and multisoliton pulses, which can be used for indoor and outdoor optical communications. Chaotic noise can be generated by a bright soliton pulse propagating inside a nonlinear microring resonator system. The results obtained show that a single temporal and spatial soliton pulse, with full width at half maximums of 75 fs, 80 fs, 700 fs, 4.4 ps, and 0.30 nm, can be generated. The add/drop system can be used to generate a high number of ultra‐short soliton pulses in the ranges of nanometer/second and picometer/second. The simulated multisolitons have full width at half maximums of 16 ps, 20 pm, 130 ps, and 35 pm and free spectrum ranges of 500 ps, 0.57 nm, 3.5 ns, and 1.4 nm, respectively. The multisolitons generated at the drop port can be used in indoor optical communications, where the ultra‐short pulses with a variety of central wavelengths (from λ = 1550 to λ = 1560) from the through port can be multiplexed‐demultiplexed along an optical fiber with a length of 50 km. The filtered signals can be obtained at the end of the transmission link used for optical outdoor communications. Copyright © 2013 John Wiley & Sons, Ltd.     

四线涡轮式慢阻肺健康监护系统研究

针对传统涡轮式肺活量计存在检测精度不高、可靠性差的问题,该文提出一种新颖的四线涡轮式检测方法,研制了一款高精度、高可靠性的慢阻肺监护系统。在硬件上,根据四线涡轮式检测方法设计了四线式呼气采集电路,提高了光路接收分辨率,并通过合理的元器件布置,减少了发光-光敏二极管相互间串扰,提高了系统的可靠性;在软件上,采用线性回归算法对其脉冲计数与分析得到用力肺活量、峰值流速等早期筛查与诊断指标。该系统利用标准Fluke气流分析仪的进行了数据标定,与传统医用涡轮式肺功能仪测试对比：用力肺活量平均相对误差由1.98%降低至1.47%;峰值流速平均相对误差由2.04%降低至1.02%。实验表明,四线涡轮式慢阻肺监护系统的呼气指标比传统慢阻肺系统检测精度更高,可靠性更好,适用于慢阻肺疾病的早期筛查与精准诊断,结合血氧饱和度、呼气末二氧化碳等指标,能实现对慢阻肺患者的医疗监护,特别对于中度和重度慢阻肺患者能起到预警和控制病情的作用。

     

High‐Performance Metal‐Substrate Power Module for Electrical Applications

This paper demonstrates the performance of a metal‐substrate power module with multiple fabricated chips for a high current electrical application, and evaluates the proposed module using a 1.5‐kW sinusoidal brushless direct current (BLDC) motor. Specifically, the power module has a hybrid structure employing a single‐layer heat‐sink extensible metal board (Al board). A fabricated motor driver IC and trench gate DMOSFET (TDMOSFET) are implemented on the Al board, and the proper heat‐sink size was designed under the operating conditions. The fabricated motor driver IC mainly operates as a speed controller under various load conditions, and as a multi‐phase gate driver using an N‐ch silicon MOSFET high‐side drive scheme. A fabricated power TDMOSFET is also included in the fabricated power module for three‐phase inverter operation. Using this proposed module, a BLDC motor is operated and evaluated under various pulse load tests, and our module is compared with a commercial MOSFET module in terms of the system efficiency and input current.     

Chirped RF Pulse Generation Based on Optical Spectral Shaping and Wavelength-to-Time Mapping Using a Nonlinearly Chirped Fiber Bragg Grating

Chirped radio-frequency (RF) pulse generation based on optical spectral shaping and nonlinear wavelength-to-time mapping in a nonlinearly chirped fiber Bragg grating (NLCFBG) is investigated. In the proposed approach, the spectrum of a femtosecond pulse generated by a mode-locked fiber laser is shaped by an optical filter that has a sinusoidal frequency response. The spectrum-shaped optical pulse is sent to the NLCFBG, to implement nonlinear wavelength-to-time mapping. A chirped electrical pulse with the central frequency and chirp rate determined respectively by the first- and second-order dispersions of the NLCFBG is then obtained at the output of a high-speed photodetector. An approximate model that describes the chirped RF pulse generation is derived, which is verified by numerical simulations. Chirped pulse generation with a pulse compression ratio as high as 450 is demonstrated. The key device in the chirped RF pulse generation system is the NLCFBG, which is investigated in detail with an emphasis on the influence of its group delay ripples on the performance of the pulse generation system. Techniques to design and fabricate the NLCFBG are also discussed. The proposed approach provides a potential solution for the generation of chirped RF pulse with a high central frequency and large chirp rate for applications in pulse compression radar systems.     

基于FPGA的数字脉冲压缩算法的设计与实现

介绍了雷达信号处理系统中脉冲压缩技术的现场可编程门阵列（FPGA ）实现方法,研究和分析了线性调频信号的脉冲压缩算法,结合研究目标和设计要求,设计了一种基于数据分段的脉冲压缩处理方法,通过SignalTap仿真证明了其有效性。     

Secure‐aware and privacy‐preserving electronic health record searching in cloud environment

Cloud storage has become a trend of storage in modern age. The cloud‐based electronic health record (EHR) system has brought great convenience for health care. When a user visits a doctor for a treatment, the doctor may be necessary to access the history health records generated at other medical institutions. Thus, we present a secure EHR searching scheme based on conjunctive keyword search with proxy re‐encryption to realize data sharing between different medical institutions. Firstly, we propose a framework for health data sharing among multiple medical institutions based on cloud storage. We explore the public key encryption with conjunctive keyword search to encrypt the original data and store it in the cloud. It ensures data security with searchability. Furthermore, we adopt the identity‐based access control mechanism and proxy re‐encryption scheme to guarantee the legitimacy of access and the privacy of the original data. Generally speaking, our work can achieve authentication, keyword privacy, and privacy preservation. Moreover, the performance evaluation shows that the scheme can achieve high computational efficiency.     

脉冲系统脉间稳定度测量

针对脉冲信号脉间稳定度测量方法不统一的问题,在分析ALLEN方差含义的基础上,提出了将ALLEN方差应用于脉冲系统脉间稳定度测量中,采用基于内插采样技术的方法进行高精度时间间隔测量,介绍了一种脉冲系统脉间稳定度测量实现方案,对实际脉冲信号源测量结果表明,提出的方法是切实可行的．     

高光束质量窄脉宽激光器

最大测程作为评估测距性能的综合性指标,成为影响武器系统作战效能的重要因素。为了研制满足作战效能的远程激光测距系统的高光束质量窄脉冲宽度种子源,采用将传统高重频电光调Q 磷酸钛氧铷晶体应用于低重频调Q的方法,实现了重复频率25Hz、脉冲宽度1.8ns、单脉冲能量1.5mJ的输出,光束质量M2<1.3。结果表明,该研究为远程激光测距系统所需窄脉冲宽度1ns~3ns、大脉冲能量200mJ、高光束质量的1064nm无水冷全固态激光源提供了合格的种子源。这一结果对高光束质量窄脉冲宽度的激光器的设计是有帮助的。