定脉冲实现心率测量

为了实现快速准确的心率测量,降低成本,放弃了通常采用的利用单片机进行定时的方法。通过分析得到心率值的大小为60f/N,利用16位计数器加外围电路实现60f个固定脉冲的输出,在此固定脉冲的作用下利用比较计数电路,在满足精度的条件下,通过合适的参数计算、器件选择,硬件上实现了60f/N的除法操作,快速准确地得到心率的测量结果。

基于现场可编程门阵列的脉冲激光引信高精度实时定距技术研究

采用电子计数法实现脉冲激光引信定距的本质是测量发射脉冲和目标反射回波脉冲的时间差。为实现脉冲激光引信的精确定距,在分析电子计数法时间测量的原理和误差因素基础上,给出了脉冲激光引信高精度实时定距的原理框图,用A ltera公司Cyc lone系列的FPGA芯片实现了时间测量模块,其高速计数器的工作频率达到800MHz,满足脉冲激光引信的精度和实时性要求。在Quartus II软件中进行了后仿真,得到了满意的结果。

引信脉冲激光装定电路抗干扰技术研究

针对设计的引信脉冲激光装定实际电路,主要分析了背景光和大气等干扰对引信脉冲激光装定系统性能的影响,采用双视场探测方法和数字相关检测技术对接收信号进行处理,并进行了实际电路改进。通过实验和分析计算,得出了电路改进前后的信噪比和信噪改善比,实验结果表明改进后的引信装定电路同时满足抗干扰和小型化要求,装定系统性能得到提高。

基于光致发光的脉冲强磁场新型定标技术

研究了脉冲经磁场测量中测量线圈有效面积的定标问题,论述了一种基于合成钻石光致发光效应的新型定标方法.介绍了脉冲强磁场的发生技术与实验装备,构建了光致发光实验测量系统,将合成钻石置于沿特定晶轴方向的应用磁场中,实验测取了1.4 eV Ni相关中心光致发光的光谱与光强,由塞曼分裂机理计算探测线圈有效截面积.由实验测量的探测线圈有效面积为813.83 mm2,与由线圈尺寸直接计算所得819.54mm2相比,误差为0.7%,说明了试验结果的可信性.

基于高精度时间间隔测量芯片TDC-GP2的脉冲激光引信定距系统

针对传统定距方法目前不能满足脉冲激光引信中近距离高精度定距要求的问题,设计一种基于高精度时间间隔测量芯片TDC-GP2的激光引信定距系统。首先介绍TDC-GP2的工作原理,并阐述其在脉冲激光测距中的应用方法,最后给出系统的硬件设计和软件方案,并进行实验分析。实验结果表明,该测量方法测量精度可达到65 ps,能满足脉冲激光测距系统中的精度要求。

集成化定相脉冲发生器

本文是对文［１］所载定相脉冲发生器的改进。这些改进使定相脉冲结构更加完善，具有更高的分辨能力和准确度，并增加了查询、游标及基波相位检出等多种功能。

提高脉冲库仑法钽丝中氧检测精度的研究

采用不同方法熔融金属钽丝,并以脉冲库仑定氧仪检测其中的氧含量。结果表明,镍浴对钽丝的助熔效果良好,可有效降低氧的分析空白值,从而使钽丝中氧的检测下限降至0.006%,测定结果RSD低于4.0%。经镍浴助熔,脉冲库仑法准确可靠,精度能满足生产中钽丝的氧分析要求。

基于水下等离子体的脉冲通信发射机

水下声通信是海洋中最主要的通信方式,在时变空变随机多途的恶劣信道中实现可靠的超远程水声通信,是一项亟待解决的难题;论文提出了一种利用水下等离子体脉冲信号、采用脉冲定宽时序编码调制方案的超远程水声通信体制,研制了一种基于水下等离子体的微型脉冲声源,搭建了基于该声源的脉冲通信发射机,实现了入水自动检测、休眠定时切换、发射频率可调、码元调制编码等脉冲通信功能;经水池试验验证,该发射机在Φ60×600 mm体积内声源级达217 dB,较好地实现预设脉冲信号的发射。

无刷直流陀螺电机的高精度恒速控制

介绍了一种能够实现三相绕组无刷直流陀螺电机的锁相恒速控制方法,所提出的定脉冲三相移电路是将高精度的参考脉冲信号移相成频率不变、相位差为120°的三组脉冲信号,分别与各相反电势检测整形的反馈信号进行相位比较,由该比较输出的数字脉冲信号直接控制电机的三相绕组导通工作。锁定时,使电机反电势的频率脉冲与参考脉冲成为一一对应的关系,电机就处于高精度恒速运行。通过样机试验,其恒速控制精度达到0.001%。

Transmission cable fault detector based on waveform reconstruction

In order to improve the accuracy of cable fault position location at a low cost and make the testing results intuitive, a cable fault detector based on wave form reconstruction is designed. In this detector, the cable fault position is located based on the time-domain pulse reflection （TDR） principle. A pulse waveform is injected in the tested cable, and a high-speed comparator with changeable reference voltages is used to binarize the test pulse waveform to a binary sequence on a certain voltage. Through scanning the reference voltage in a full voltage range, multi-sequences are acquired to reconstruct the pulse waveform transmission in the cable, and then the pulse attenuation feature, electrical open circuit fault, electrical short circuit fault, and the fault position of the cable are diagnosed. Experimental results show that the designed cable fault detector can determine the fault type and its position of the cable being tested, and the testing results are intuitive.

基于不同作用体制的激光引信探测技术

随着激光技术的飞速发展,半导体激光传感器已被广泛应用于近炸引信领域。对目前广泛使用的激光近炸引信体制中的几何截断定距、距离选通定距、脉冲鉴相定距以及伪随机编码定距的原理、特点进行了分析,指出了每种体制的局限性,为应用在具体背景下的激光近炸探测体制的选择提供了一定的参考价值。

基于在线分级恒流充电的蓄电池智能管理系统研究

提出了基于在线分级恒流充电的蓄电池智能充放电管理系统方案,将原有的开关电源恒压充电方式改为在线分级定电流恒流脉冲方式充电,该系统方案可以大幅提高维护效率、有效延长蓄电池使用寿命。

The Global Solutions of Impulsive Retarded Functional Differential Equations

In this paper, we present some results on the existence of the golbal solutions of nonlinear impulsive retarded functional differential equations.

Asymmetry of Photoelectron Angular Distributions in Molecules by Intense Attosecond Extreme Ultraviolet Laser Pulses

We present photoelectron angular distribution of the aligned molecular ion H2^＋ by intense ultrashort attosecond extreme ultraviolet laser pulses from numerical solutions of timedependent Schrodinger equations. Photoionization from a superposition state of the ground 1sσg and the excited 2pσu states with pulses at photon energies above the ionization potential, hω〉Ip, and intensity 10^14 W/cm^2, yields pulse duration dependent asymmetry of photoelectron angular distributions. We attribute the asymmetry to the periodical oscillation of the coherent electron wave packets, resulting from the interference of the two electronic states. For the processes with long pulse durations, such duration dependence is absent and symmetric angular distributions are obtained.

Asymptotical p-Moment Stability of Stochastic Impulsive Differential Equations and Its Application in Impulsive Control

In this paper, the asymptotical p-moment stabifity of stochastic impulsive differential equations is studied, and a comparison theory to ensure the asymptotieal p-moment stability for trivial solution of this system is established, from which we can find out whether a stochastic impulsive differential system is stable just from a deterministic comparison system. As an application of this theory, we control the chaos of stochastic Chen system using impulsive method, and a stable region is deduced too. Finally, numerical simulations verify the feasibility of our method.

Computational fluid dynamic simulation of an inter-phasing pulse tube cooler

An inter-phasing pulse tube cooler (IPPTC) consists of two pulse tube units, which are connected to each other at hot ends of the pulse tubes through a needle valve. This paper presents the computational fluid dynamic (CFD) results of an IPPTC using a 2D axis-symmetrical model. General results such as the phase difference between pressure and velocity at cold end and hot end, the temperature profiles along the wall, the available lowest temperature as well as its oscillations and the coefficient of performance (COP) for IPPTC are presented. The formation of DC flow and its effects on the performance of the cooler are investigated and analyzed in detail. Turbulence, which is partially responsible for the poor overall performance of a single orifice pulse tube cooler (OPTC), is found to be much reduced in IPPTC and its performance is improved significantly compared with the single OPTC.

Effects of Pulse Ultrasound on Adsorption of Geniposide on Resin 1300 in a Fixed Bed

The effects of pulse ultrasound with different pulse parameters on the breakthrough curves of Geniposide on Resin 1300 were studied. The mass transfer model describing the adsorption process was constructed. Adsorption capability and the overall mass-transfer coefficient were obtained by fitting the constructed mass-transfer model and the experimental data. The effects of pulse ultrasound on adsorption of Geniposide on Resin1300 in a fixed bed were studied and compared. Amount of Geniposide adsorbed on Resin 1300 in the presence of ultrasound is lower than that in the absence of ultrasound, but the mass-transfer rate with ultrasonic irradiation is higher than that without ultrasound. Furthermore, mass transfer rate is enhanced by pulse modulation. In the conditions studied, the adsorption equilibrium constant decreases with increasing ultrasonic power, while the overall mass-transfer co-efficient increases. With increasing pulse duty ratio, adsorption equilibrium constant decreases initially, reaches a minimum when pulse duty ratio is 0.5, and then increases. On the contrary, the overall mass-transfer coefficient in-creases initially and reaches a maximum when pulse ratio is 0.5, and then decreases. Effects of pulse period on ad-sorption equilibrium and mass transfer rate reached the peak at pulse period of 28.6 ms.

The Stability of Logistic Model with Random Impulse

This paper is devoted to studying the stability of Logistic model with random impulse by using the theory of Markov skeleton processes and a convenient condition for Logistic model with random impulse to be stable is given.

Graphene-gold Nanoparticle Composite Film Modified Electrode for Determination of Trace Mercury in Environmental Water

The graphene-gold nanoparticles composite film modified glassy carbon electrode （EG- AuNPs/GCE） was prepared by one-step coelectrodeposition and employed for determination of trace mercury in environmental water with differential pulse stripping voltammetry. Such a nanostructured composite film combined with the advantages of gold nanoparticles and graphene, can greatly promote the electron-transfer process and increase accumulation abil-ity for Hg（Ⅱ）, leading to a remarkably improved sensitivity. The linear calibration curve ranged from 0.2 μg/L to 30 μg/L for Hg（Ⅱ） and the detection limit （S/N=3） was found to be 0.03 μg/L at a deposition time of 300 s. Moreover, the stablity of the as-prepared electrode and interferences from other substances were evaluated. The modified electrode was successfully applied to the direct detection of Hg（Ⅱ） in real water samples.

INSTANTANEOUS DOPPLER FREQUENCY FOR SQUINT SAR IMAGING

Instantaneous Doppler frequency for squint SAR imaging has been found with ChirpScaling Algorithm (CSA). Because the azimuth sample is not perpendicular to the range sample,the range signal must impact on the azimuth signal in the squint SAR data processing, andthe different slant range targets have different Doppler frequencies. From the mathematicalmodel of SAR echo signal, this paper carefully analyzes the instantaneous azimuth frequency, theinstantaneous Doppler frequency component of the azimuth frequency and the impact of rangechirp on azimuth frequency, which explains that Doppler frequency should be properly selected forcorrect SAR imaging in the squint SAR. The results of point target simulation experiments showthat the way is reasonable for the squint SAR and can effectively complete range compressionand azimuth focusing, and improve images' quality.