Forced nonlinear precession of the magnetization vector under the conditions of an orientation transition

Forced nonlinear precession of the magnetization vector in a normally magnetized magnetic plate under the conditions of an orientation transition is considered. It is shown that, in the field lower than the form demagnetization field, the variable circularly polarized field causes precession of the equilibrium position of the magnetization vector. It is demonstrated based on a vector model in which the precession period of the equilibrium position is inversely proportional to the squared amplitude of the variable field and the sine of the angle of deviation of the equilibrium position of magnetization from the constant field. It is shown that the critical parameters necessary for excitation of precession of the equilibrium position are the amplitude and frequency of the variable field. Diagrams determining domains of existence of precession of the equilibrium position for different saturation magnetization of a magnetic plate are constructed in terms of the coordinates variable field amplitude-frequency. The role of dissipation of magnetization oscillations in the determination of the critical parameters is elucidated. The features of precession in the presence of asymmetric excitation and in the presence of anisotropy in the plane of the plate are noted.     

多光子Tavis-Cummings模型中运动原子与二项式光场相互作用的量子纠缠

利用全量子理论,研究了多光子Tavis-Cummings模型中运动原子与二项式光场相互作用系统的量子纠缠特性,讨论了不同初始状态下的二项式光场系数和原子运动速度对纠缠特性的影响.结果表明：二项式光场系数不影响场熵演化的周期性,但影响场熵峰值大小.随着原子跃迁光子数的增多,场熵演化的周期性和消纠缠现象逐渐消失.原子运动的速度影响场熵的演化周期,且影响场熵峰值的大小,而原子跃迁光子数的增大,会消弱原子运动速度对场熵演化的影响.当光场处于中间态,原子运动速度较低,且原子跃迁光子数较大时,光场与原子可以长久地处于量子纠缠态.     

有线电视加解密系统研究

有线电视加解密技术是有线电视付费管理的一个重要技术保障。在发射端,先将各路电视视频信号进行同步时基校准后,根据同步图案数据确定的同步图案实现每一路电视信号的同步信号的时基处理,以完成电视信号加密(加扰),随后将各路加密(加扰)电视信号连同数据的调制信号一起发送。在接收端,先根据射频信号解调出同步图案数据,并根据解调出的同步图案数据对射频信号进行群解密(解扰),从而实现了电视信号的单加群解。     

硬盘盘片结构特点及NiP基板CMP研究

分析了硬盘盘片的结构特点及硬盘基板的作用。在超净实验室中,通过调节氧化剂的含量,对硬盘基板进行了化学机械抛光。分析了不同氧化剂的含量对硬盘基板抛光速率的影响。对抛光后的硬盘基板进行了检测。抛光后的硬盘基板的粗糙度基本达到厂家的要求。对有可能造成硬盘基板划伤的原因进行了分析研究,为下一步解决划伤问题的实验提供了理论依据。     

Berechnungsmethoden zur Ermittlung der Schutzstrecke bei U- und Stadtbahnen

One essential component of project planning of train control system plants is the design and calculation of the protective route. At first, definitions of the most important terms are explained. There are three different calculation methods depending on the regard of the slope of the track system as well as on the train mass representable. The simplest method only considers the maximum slope before the signal and the danger point. The second method considers the slope of the track in the form of stairs. The gradient method is presented as a third method. The regard of the inclination gradient occurs here in the form of a twofold averaging. On the one hand the mean value in the form of an integral is formed via the train length. On the other hand averaging occurs in the form of an integral via the braking distance. The middle inclination value found in this way is inserted in the iterative process for the determination of the protective route.     

无驱动硅微机械陀螺

报道了无驱动结构硅微机械陀螺,推导了输出电压方程。从方程表达式可看出,该陀螺输出信号包含旋转载体的偏航和俯仰角速度及自旋角速度的信息。通过实验说明如何在输出信号中提取相关信息,即输出信号的频率表示载体自旋角速度的平均值,输出信号的包络表示载体偏航和俯仰角速度大小的瞬时值,输出信号的极性由输出波形的相位超前和滞后确定。最后给出该陀螺目前所达到的主要性能指标。     

基于红外测温的柜内元件热故障的反问题识别

结合红外辐射理论分别建立了控制柜内部单个和多个元件同时过热时对壳体内表面的红外辐射模型,得到了壳体内表面总的热流密度分布,并针对受热壳体建立二维热传导模型。基于对壳体表面红外成像测温,运用L-M算法进行了导热反问题模拟研究,对控制柜内部单个和多个元件的发热温度和方位进行了识别,最后分析了测量误差对计算结果的影响。结果发现运用L-M算法对单个和多个故障元件的发热温度和方位进行分开反演求解和同时进行反演计算时,都取得了较好效果,求解精度较高。测量误差对发热温度的反演计算结果影响更大。     

激光干扰行间转移CCD串扰现象研究

分析了激光功率密度增加到原来的10倍的时候,激光干扰行间转移CCD的串扰图像部分的灰度值并不是成比例地增加,并对串扰图像进行了仿真。由于光电二极管的溢出是不断进行的,垂直CCD的每个像元都获得所有超过阈值的像元溢出的光生载流子之和。每个超过阈值的像元溢出的光生载流子等于垂直CCD向下移动一个像元所需的时间内溢出的光生载流子。通过求解感光部分中光生电子遵守的方程,得到电子浓度增量和入射光功率的关系,进而仿真出串扰图像。仿真了激光能量为串扰阈值10倍和100倍量级时的串扰图像,仿真结果和实验结果可比。     

Phase-only synthesis of nulls in the sum and difference radiation patterns of the phased array antenna of a coordinate meter

Two approaches to the phase-only synthesis of nulls in radiation patterns (RPs) of the phased array antenna (PAA) of a coordinate meter are considered. The approaches use the specificity of the structure of the sheet of the measuring PAA. Such a PAA forms the sum RP and two difference RPs, which ensure measuring of the angular coordinates of an object. The problem of the phase-only synthesis of pattern nulls in prescribed directions in one or several PAA RPs with the angular orientation of the nulls of difference RPs kept in the RP scanning direction is solved. Design relationships are derived and a RP synthesis method, which is based on iterative univariate minimization of a nonlinear functional and includes analytic determination of the minimum of this functional at each iteration, is described. Examples of the array pattern synthesis are presented. The effect the phasing increment on the depth of formed nulls is analyzed and the dependence of the value of the PAA RP in the scanning direction on the position of the formed null is investigated. The effect of synthesized nulls on the shape of the PAA direction-finding characteristic is analyzed.     

A method for the measurement of the parameters of a two-layer stratified earth

A two-layer stratified model is assumed for the earth. The distances involved are assumed to be sufficiently short that the earth can be considered flat. The measurement of the parameters of the top layer can easily be made from the surface, but the parameters of the lower layer are somewhat more difficult. A method is given for the evaluation of these quantifies in terms of measurements of propagation between two antennas located at the surface of the earth. The theoretical solution for the field of an antenna located at the surface of a flat stratified earth has been given by J. R. Wait. This solution is taken as the starting point; it is put into a form which explicitly shows the influence of the parameters of the lower layer. The method of least squares is then used to evaluate the unknown parameters in terms of the measurements. This process allows the use of a large number of measurements which are essentially subjected to an averaging procedure. This prevents localized irregularities in the earth's surface from unduly affecting the results.     

激光跟踪中目标卫星表面BRDF对回波信号的影响

通过双向反射分布函数(BRDF)公式,模拟了空间激光主动照明跟踪中,相同材料、不同粗糙度下卫星表面的BRDF,得出了随着卫星表面材料粗糙度的增加,镜面反射分量越小,漫反射分量越大,双向反射分布散射角越宽,接收到的回波信号对方向的敏感性减小。同时模拟了入射角度对卫星表面BRDF的影响,得出了照明光束小角度入射、接收信号方向与照明光束方向一致时,镜面反射分量的增加增强了反馈信号,当大角度入射时,反馈信号急剧减小。当入射角大于34°时,通过卫星表面BRDF计算得到的最小接收功率,比之前把卫星目标看成朗伯体,通过激光雷达公式计算得到的最小接收功率小。得出了增加照明光束的发射功率为原来的5倍,或者增大接收口径为原来的2.5倍,可以消除大入射角度带来的接收功率的减小,使得系统有4倍的功率余量。     

新型双通道可选择性SPR光纤传感器的研究

设计了一种双通道表面等离子体共振光纤传感器,分析了Au、Cu两种材料对波长调制型表面等离子体共振光纤传感器的影响,优化了金属厚度并且选取优化后的金属厚度dAu=47 nm,dCu=53 nm进行数值仿真分析。结果表明,金属层为金的通道比金属层为铜的通道灵敏度高,但是金属层为铜的通道比金属层为金的通道检测精度高4倍;金属层为金的传感通道适合检测折射率较低的物质,而金属层为铜的传感通道适合检测折射率较高的物质,该传感器的提出扩大了单一传感器的应用范围,并且文中提出的传感器比传统的SPR传感器检测精度高,灵敏度和单通道传感器一样。     

关于物联网应用若干关键问题的研究

在当今社会物联网是一个新兴的产业同时也是人们研究的重点.但是不管是对于物联网的认识还是对于物联网的研究都还处在初步的探究阶段.本文立足于物联网的概念,对我国物联网的发展现状以及发展中存在的问题进行分析.并且对物联网的关键性技术进行阐述.希望更好的促进我国物联网技术的发展.     

基于铝片取向的复合热控涂层吸收发射比调控

金属颗粒掺杂型复合涂层是重要的航天器热控材料,除了粒子材料、尺寸、体积分数、几何形貌、涂层厚度等常规调控手段,颗粒的取向也是影响涂层辐射特性的重要因素。颗粒取向可以通过改变工艺参数或使用定向剂控制,然而目前关于颗粒整体取向对涂层吸收发射比的影响规律尚不清晰,而且现有的采用二流法的研究中大多都将散射假定为各向同性。以热控涂层中常用的大尺寸铝片粒子掺杂型复合涂层为计算模型,采用考虑衍射的几何光学方法和考虑各向异性散射的二流法研究了铝片取向角对热控涂层吸收发射比的调控规律,同时考虑了铝片体积分数和涂层厚度等因素。结果表明：通过调节粒子取向可实现涂层吸收发射比在0.48～1.69范围内的调控。涂层平均吸收率和平均发射率在铝片取向角超过45°时明显增大。涂层吸收发射比在铝片取向角45°附近最小,并且随铝片体积分数的增大而减小。研究表明：通过控制粒子的整体取向可有效实现吸收发射比的调控,为热控涂层的设计和调控提供了新的思路。     

四像限光电探测器的光路数学模型

探测器数学模型是探测器实施精确探测的基础。通过分析探测器光路建立了一个较为完整的四像限光电探测器的光路数学模型．考虑了探测器在安装过程中发生的偏移位置及其偏移量、光敏面的离焦量、探测器结构参数等对光信号到电信号的转换的影响。在建立俯仰偏移、横滚偏移和方位偏移三种特定情况下探测器模型的基础上．给出了探测器的三自由度安装位置、光敏面的离焦量、光信号等与输出信号的一般关系式。比较在给定相同光路参数条件下探测器光路数学模型的理论输出信号波形与实测输出信号波形，结果表明，两者信号波形相似。比较模型输出与实际输出信号的两个特征参数．即信号过零点的切线的斜率与截距，可以发现，特征参数的差别小于0．01，因此。四像限光电探测器数学模型的输入输出关系与探测器实际输入输出关系是一致的，可以用该模型实施探测器探测。这为光电探测器进一步的研究与应用．实现无实验样本探测提供了参考。     

结合CGH与辅助透镜的长焦距非球面反射镜检测（特邀）

目前,一些大口径光学望远镜主镜的曲率半径已经达到了几十米量级,若单纯利用计算全息实现对镜面进行面形检测,则检测光路长度不低于其曲率半径长度。受场地大小及环境气流扰动等因素的限制,该条件下难以实现对镜面的高精度测量。为了解决大口径长焦距光学镜面的高精度面形检测问题,提出了一种混合补偿干涉检测方法。该混合补偿方法结合了计算全息图和辅助透镜,在有效地缩短检测光路长度的前提下,可以实现对非球面镜面的零位补偿干涉测量。在光路设计中,需要有效地实现混合补偿光路光学设计参数优化以及对CGH衍射级次的分离;同时,检测光路长度应小于非球面反射镜曲率半径大小,以实现缩短检测光路长度的目的。通过对EELT主镜镜面进行仿真检测,结果表明:该方法检测光路长度可缩短至镜面曲率半径长度的1/8以内,设计检测精度优于RMS λ/100 （λ=632.8 nm）。上述仿真结果证明了该方法可以在缩短检测光路长度的情况下实现对待测非球面反射镜的高精度面形检测。     

红外无线信道特性的评价方法

基于评价室内红外无线通信信道的目的,采用改进的朗伯定律描述室内表面的漫射特性,分析了信道中直射及漫射分量的大小,定义了评价红外无线信道的瞬态响应及时延的表达方法,并针对几个实用信道进行了模拟。结果表明,光接收机的ＦＯＶ及位置的变化对信道特性的影响较大。通过信道特性的分析比较,对构成高健壮性的室内光无线通信信道有积极意义。     

激光切割质量的在线评价方法

在工艺实验的基础上,建立了切割面分层理论模型.实验研究和模型分析均表明:切割面近下缘处是切割质量的最薄弱环节,此处粗糙度最高,切割前沿在下缘处的温度是决定下缘质量的主要因素.提出以近下缘粗糙度作为切割质量评价和检测的主要指标,建立了火花簇射的视觉检测系统,从侧面研究了切割过程中的火花簇射行为,发现火花簇射视觉图像特征与切割速度以及切割面近下缘粗糙度之间具有良好的对应关系:随着切割速度的变化,最高的火花簇射出口温度(亮度)对应于最低的切割面近下缘粗糙度,此时的切割速度为该工艺条件下的最佳切割速度,从而实现了对切割面下缘质量的在线检测.     

Excitation of surface waves on a unidirectionally conducting screen by a phased line source

The excitation of surface waves on a unidirectionally conducting screen produced by a phased line source located above the screen and perpendicular to the wire elements is considered. The screen consists of an infinite number of straight, perfectly conducting, parallel wires and conducts only in the direction of the wire elements. The phased line source consists of a periodic line current with an electric charge distributed along its length. The complete electromagnetic field is determined exactly and simple expressions are given for the scattered far field. It is shown that surface waves exist and simple expressions for the amplitudes are given. Another principal result is the determination of the magnitude of the complex Poynting vector for the radiated power. It is found that the pattern function lies on a cone independent of the presence of the screen and that the cone angle depends only on the phasing of the source. The pattern function at points below the screen is independent of the location of the source above the screen. Furthermore, the pattern function vanishes in the direction of the screen and this seems concomittant to the existence of surface waves. Two pattern functions are drawn for typical cases of interest. The power propagated by the surface waves is also determined. The method employed to solve the problem is based on the deduction that the scattered magnetic field component in the direction of the wire elements is zero. A consequence of this deduction is that the electromagnetic field can be derived from a single scalar wave function that satisfies a partial differential equation in the plane of the screen and a jump condition across the screen. This method is quite general and can be applied to a large class of interesting propagation problems arising from different types of excitation. The scattered far field is obtained using another method that is algebraic in character and does not require a complete solution of the problem.     

磁粉制动器加载性能试验研究

针对电梯载荷试验替载装置组合加载过程中对磁粉制动器性能研究的不足,文中提出对磁粉制动器加载性能进行试验研究。搭建基于三相异步电机试验平台,对磁粉制动器的加载响应时间、输出扭矩等进行性能试验,试验结果分析得到:磁粉制动器加载响应存在一定的滞后性,加载响应时间为12.5 s,电机转速对磁粉制动器加载响应时间没有影响;磁粉制动器的控制电压在0.3~1.3 V范围内,其输入电压和输出扭矩呈线性关系;当磁粉制动器的控制信号一定时,电机转速越大,磁粉制动器的输出扭矩越稳定。试验研究结果为磁粉制动器应用在电梯载荷试验替载装置中提供了试验依据。