便携式多通道数据采集系统设计

在EAST全超导托卡马克核聚变放电实验中,某些信号需要低功耗、便捷的进行独立同步采集与分析;而现有的大型采集系统并不能满足此需求,所以需要设计一套低功耗的、便携式的多通道数据采集系统来保障EAST实验的顺利进行。系统具有界面友好、性能稳定等诸多优点。在LabVIE软件编程环境中,系统能够实现对多达32路信号的同步采集、实时显示、数据存储、数据分析以及历史数据回放等功能。经过实验测试,该系统运行稳定可靠,完全满足EAST实验的数据采集需求。     

基于LabVIEW&DIAdem的飞机电源测试系统

试验环节是产品研制生命周期中的重要环节,但是一直以来都缺乏有效的管理手段,在整个测试阶段都存在大量的人为的、重复性的工作,导致试验效率低下,为改善这一现状,提高试验效率,提出了一种基于PXIe数据采集系统,借助LabVIEW和DIAdem软件的测试系统解决方案:以LabVIEW控制数据高速同步采集,DIAdem调用LabVIEW模块执行算法分析,通过软件集成,实现对测试系统的全面管理,包括数据采集、数据检索、数据分析、报表生成及整个流程的自动化控制;以C919飞机电源测试系统为介绍对象,对该套测试系统解决方案进行阐述,实际测试情况表明,在数据吞吐率大于200 M/s的情况下,相对传统测试方法,该测试方案在保证测试精度的基础上,极大的提高了试验效率,极大的提高了系统的可扩展性和可维护性。     

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介绍了一种处理HL-2A汤姆逊散射原始实验数据的新方法——最大似然法。该方法用数理统计的手段,通过使理论推导出的数据与实际采集到的散射数据最大可能的一致,得到了较准确的等离子体电子温度Te和密度ne。将计算所得的结果与现在汤姆逊散射系统所用的比值法得到的结果相比较,验证了该方法的可适用性,并能够克服比值法的一些缺陷。     

飞行试验多源iNET数据精密分析技术研究

为了解决飞行试验测试系统跨代升级,网络化测试系统采集记录的多源iNET试飞数据的精密分析难题,针对新形势下的网络化测试系统应用于飞行试验所特有的多源数据测试技术架构,分析了该测试技术架构的特点,以及精密分析对试飞工程师验证测试系统同步采集及数据同步分析算法的重要性,提出了基于数据流StreamID的测试参数iNET精密分析方法及实现技术,实现了多源iNET试验数据的精密分析;最后在采用了网络化测试系统的某试验机的飞行试验中对多源iNET数据进行了精密分析,试验表明使用这些算法的数据处理软件满足飞行试验iNET精密分析的需求。     

飞参系统实时监视技术研究

针对飞机研制阶段各系统交联试验时故障定位慢、检查测试手段匮乏的问题,设计了飞参系统的实时监视功能。飞参系统中的机载设备与地面设备通过以太网进行数据交互,实现飞机状态的实时监视。分析了实时监视功能的作用与优势,并从某型飞参系统功能需求出发,阐述了机载设备的硬件配置及软件架构。基于UDP通信协议,提出了一种机载设备与地面设备交互的数据收发策略。该策略通过地面设备控制数据通信周期,机载设备采集的数据按周期发送给地面设备还原显示,实现了飞行数据的一边记录一边监视。实际应用表明,飞参系统的实时监视功能丰富了试验测试手段,提高了各个系统试验效率,实现了对飞机实时状态的监测,为航前快速检测技术的发展奠定了基础,具有很高的工程实用价值。     

基于LabVIEW的罗柯线圈数字积分器的设计与实现

为满足使用罗柯线圈对超导导体的临界电流测试的需求,本文基于LabVIEW的同步采集与实时处理技术,设计了一套可搭配罗柯线圈的数字积分器,实现对罗柯线圈输出数据的采集与实时积分处理、显示以及数据回放等功能。该数字积分器相比模拟积分器具有易使用、误差低、低漂移等优点。实验测试结果表明该数字积分器的测试误差最大为0.8%,满足目前高温超导导体电流测试的要求。     

可接入射频半实物的试验数据转换系统设计与实现

试验环节是产品研制生命周期中的重要环节,但是一直以来都缺乏有效的管理手段,在整个测试阶段都存在大量的人为的、重复性的工作,导致试验效率低下,为改善这一现状,提高试验效率,提出了一种基于PXIe数据采集系统,借助LabVIEW和DIAdem软件的测试系统解决方案：以LabVIEW控制数据高速同步采集,DIAdem调用LabVIEW模块执行算法分析,通过软件集成,实现对测试系统的全面管理,包括数据采集、数据检索、数据分析、报表生成及整个流程的自动化控制。本文以C919飞机电源测试系统为介绍对象,对该套测试系统解决方案进行阐述,实际测试情况表明,在数据吞吐率大于200M/S的情况下,相对传统测试方法,该测试方案在保证测试精度的基础上,极大的提高了试验效率,极大的提高了系统的可扩展性和可维护性。     

水下双层加肋圆柱壳全空间收发分置散射声场快速预报方法

针对水下双层加肋圆柱壳的全空间收发分置散射声场求解,提出了一种快速预报方法。该方法将散射声场表示为声散射传递函数与声源密度函数的乘积,以目标表面网格信息、少量的仿真或测试多基地散射声压数据作为已知信息,借助数值积分、矩阵理论、最小二乘法对其他收发分置散射声场进行预报。分别以有限元仿真和试验测试的散射声压数据作为输入,对水下双层加肋圆柱壳的多基地散射声场进行了计算,并与完全采用有限元方法的计算结果进行了对比。结果表明:该方法在目标表面结构和部分散射声场数据已知条件下能对目标的全空间收发分置散射声场进行预报;已知散射声压数据量越多,计算频率越低,预报精度越高。     

空间多普勒激光雷达地面散射信号分析

为了扩展空间多普勒激光雷达地面散射信号的应用范围,采用多个机载多普勒激光雷达飞行实验数据,对地面散射信号的强度、海拔高度、速度等特征进行了数据分析,并利用地面散射信号与上层大气信号强度的比值,可以等效体现地面反射率特征,即地面散射信号解算的海拔高度与数字海拔高度模型数据相吻合,两者平均值偏差小于20 m,标准偏差小于100 m;使用地面散射信号实现飞机速度校正,与使用飞机平台数据解算的结果具有较好的一致性,采用直接探测手段时,标准偏差小于1.5 m/s,采用相干探测手段时,标准偏差小于0.5 m/s,验证了利用地面散射实现空间平台速度校正的可行性。另外,针对云散射信号的存在和影响,提出了一种利用海拔高度数据比对的方法,实现云散射和地面散射的识别。     

基于CCD成像的侧向散射激光雷达几何标定方法

通过分析CCD成像特点,设计了侧向散射激光雷达几何标定实验,得到CCD各像元的角宽度,并确定了CCD像元与散射光位置之间的对应关系.对两次实验中采集的回波信号进行标定,并分别与POM02进行相函数比对、与后向散射激光雷达进行探测信号比对,结果表明:相函数廓线和POM02测量结果相吻合;侧向散射激光雷达信号与后向散射雷达的距离修正信号在650m以上的变化趋势一致.侧向散射激光雷达弥补了后向散射激光雷达在近地面段不能探测气溶胶的不足,该标定方法可靠,为进一步利用侧向散射激光雷达研究近地面气溶胶的时空分布奠定了坚实的基础.     

基于宽带光源和自外差检测的布里渊光时域反射温度传感系统

为简化系统结构、减小相干瑞利噪声对系统性能的影响,提出了一种采用宽带光源的瑞利和布里渊散射自外差检测布里渊光时域反射温度传感系统.分析了瑞利和布里渊自外差检测原理,研究了布里渊频移和自外差信号功率与光纤温度和应变的关系.设计并搭建采用宽带光源的自外差检测布里渊光时域反射温度传感系统,获得了常温下沿光纤分布的自外差信号功率谱及不同温度时加温段光纤的功率谱,验证了布里渊频移和自外差信号相对功率变化随温度的线性增加关系.通过实验数据获得的布里渊频移和相对功率变化的温度系数分别为1.07±0.01MHz/℃和(0.37±0.09)%/℃.本文的研究结果为基于瑞利和布里渊自外差检测布里渊光时域反射传感系统的温度和应变同时测量提供了理论和实验依据.     

Time resolved scattering relaxation mechanisms of microcavity polaritons

We study the polariton relaxation dynamics for different scattering mechanisms as: Phonon and electron scattering procesess. The relaxation polariton is obtained at very short times by solving the Boltzman equation. Instead of the well-known relaxation process by phonons, we show that the bottleneck effect relaxes to the ground state more efficiently at low pump power intensity when the electron relaxation process is included. In this way, we clearly demonstrate that different relaxation times exist, for which any of these two mechanism is more efficient to relax the polariton population to the ground state.     

Nonresonant interaction of femtosecond laser pulse with centrosymmetric molecules

We have derived a system of equations that describes the evolution of the density matrix of a centrosymmetric molecule interacting with a single nonresonant femtosecond laser pulse. The dynamics of the ground electronic state is expressed in terms of the effective Hamiltonian and the coherences between the ground an excited electronic states are functionals of the ground state density matrix. Using the time-dependent perturbation theory, we have calculated the energy deposited in the molecule as a result of rotational stimulated Raman scattering. The effective absorption coefficient is found to be proportional to the fourth power of the pulse amplitude and has a resonance-like dependence with respect to the pulse duration.     

近距离雾的激光多次散射模拟

为了满足精确快速获取雾的多次散射仿真需求,在近程雷达距离较近情况下,将雷达方程和Mie散射理论相结合,提出一种快速有效的激光多次散射计算方法.首先通过雾滴谱模型建立雾颗粒的几何模型,然后根据Mie散射理论获得的单个粒子的散射函数计算激光在雾模型中单个颗粒的一次散射和二次散射功率密度,结合雷达方程推导出雾的多次等效散射截面和散射系数计算函数.模拟计算表明:雾的激光二次等效散射截面与雾浓度的2/3次方成正比,二次散射系数随能见度增加的衰减比一次散射系数快.     

Inelastic collisions of ultracold heteronuclear molecules in an optical trap

Ultracold RbCs molecules in high-lying vibrational levels of the a3Sigma+ ground electronic state are confined in an optical trap. Inelastic collision rates of these molecules with both Rb and Cs atoms are determined for individual vibrational levels, across an order of magnitude of binding energies. The long-range dispersion coefficients for the collision process are calculated and used in a model that accurately reproduce the observed scattering rates.     

A two-step strategy for numerical simulation of radiative transfer with anisotropic scattering and reflection

This article presents a two-step procedure for the computation of radiative heat transfer with anisotropic scattering and reflection. It is based on a concept that the coincident processes of absorption and scattering/reflection can be separated factitiously. All medium elements and wall surfaces are supposed to be pure-absorbing when receiving incident radiation. Afterwards they emit the scattered/reflected radiations. The absorption of both the initial and the secondary radiations can be assessed by the direct exchange area. It is needed to repeat the processes for a few times until the radiations are substantially absorbed. For anisotropic scattering/reflection, a vector summation obtains the directional distribution of emissive power. The method is validated by several benchmark computations in terms of emissive power and heat transfer coefficients. It is shown that the method gives more accurate solution than the isotropic scaling for the heat transfer in anisotropically scattering media.     

FDTD方法分析高功率微波粗糙地面散射特性

采用时域有限差分方法(FDTD)对高功率微波(HPM)近地面传输进行了仿真,其中提出的一种完全匹配层-广义完全匹配层混合吸收边界,较好地抑制了常规FDTD方法在计算低掠射角入射时产生的边缘绕射现象。将理想水平地面数值计算结果与解析法结果对比验证计算模型的正确性,通过数值计算结果分析高功率微波粗糙地面的散射特性。理论分析和仿真结果表明:粗糙地面对散射系数变化影响较明显,从宏观角度上看,散射系数曲线同理想水平地面散射系数曲线相似,即随掠射角的增大散射系数先减小后增大;从微观角度上看,由于粗糙地面的作用,其散射系数曲线并不存在布鲁斯特角,且在某一区域并非单调增加或减小。     

Dilute neutron matter on the lattice at next-to-leading order in chiral effective field theory

We discuss lattice simulations of the ground state of dilute neutron matter at next-to-leading order in chiral effective field theory. In a previous paper the coefficients of the next-to-leading-order lattice action were determined by matching nucleon-nucleon scattering data for momenta up to the pion mass. Here the same lattice action is used to simulate the ground state of up to 12 neutrons in a periodic cube using Monte Carlo simulations. We explore the density range from 2% to 8% of normal nuclear density and analyze the ground-state energy as an expansion about the unitarity limit with corrections due to finite scattering length, effective range, and P -wave interactions.     

Investigation on the scattering effect of ceramic Nd:YAG

This paper investigates the scattering effect of domestic 0.5 at{\%} ceramic Nd:YAG. An effective method has been utilized to measure the scattering and absorption coefficients. An end-pumped continuous wave (CW) Nd:YAG ceramic laser was also demonstrated. A maximum output power of 6.7~W at 1064~nm was obtained at an 808-nm pump power of 32.9~W. Conversion efficiency and slope efficiency have been achieved. This indicates that scattering has an important effect on the optical performance of ceramic Nd:YAG.     

Normal quasiparticle scattering and kinetic effects in degenerate semiconductors

The influence of normal processes of electron-electron and phonon-phonon scattering on quasiparticle momentum relaxation in nonequilibrium electron-phonon systems of degenerate semiconductors is investigated. A system of kinetic equations is solved for the electron and phonon distribution functions, and the kinetic coefficients of a semiconductor are calculated in the linear approximation in the degeneracy parameter. The influence of normal scattering of quasiparticles on the electrical conductivity, thermopower, and heat conductivity of a degenerate semiconductor is analyzed. Redistribution of the phonon momentum in N processes within each branch of the vibrational spectrum, as well as among different branches, is taken into account.