多气隙电阻板室飞行时间谱仪技术

基于多气隙电阻板室(MRPC)技术的飞行时间谱仪广泛应用于现代物理实验,并在粒子鉴别中发挥了重要作用.随着加速器能量和实验亮度的提高,对飞行时间谱仪的粒子计数率和时间分辨要求越来越高.MRPC飞行时间谱仪按技术上可以分成三代.从第一代到第三代,计数率要求越来越高( 30 kHz/cm~2),时间精度也更加严格(20 ps),相应的探测器结构和读出电子学系统呈现出不同的特性.本文总结了三代飞行时间谱仪技术的主要技术特点及主要物理实验,介绍了已经取得的应用成果,提出了该技术的未来发展方向.同时也介绍了MRPC探测器在工业及医学方面的应用.     

基于ROM技术的阵风响应分析方法

阵风响应分析是大型飞机设计过程中必不可少的环节. 现有的阵风响应分析主要采用基于线化升力面理论的气动力模型,不能考虑到各种非线性效应,不适合于跨音速气动弹性的分析. 基于CFD技术,采用系统辨识方法,在状态空间内建立了降阶的非定常气动力模型(reduced order model, ROM). 耦合结构运动方程、非定常气动力模型(结构运动)、外激阵风的气动力模型,建立了基于CFD技术的阵风响应分析模型.算例研究了某一典型机翼在方波激励下的阵风响应问题,对比了各阶模态位移的响应以及翼根弯矩的响应. 基于ROM技术的计算结果与CFD/CSD直接耦合仿真结果吻合,证明了该方法的正确性和精度.      

混响背景下数字声呐回音检测的一种新的幅度显示方法

本文介绍数字声呐中回音系统幅度显示的一种方法，它可以消除近场混响背景的模糊，提高测检性能，海上实际使用证明，显示效果清晰、稳定、分辨率高，远场噪声背景下无虚警。     

关于投入产出模型应用研究的一点注记

本文对[1]中价值型投入产出模型在更一般的情况下,给出了由于一个或若干个部门的产品价格和固定资产折旧的变动,对其他各部门的产品价格和收入可能产生的影响的计算公式。     

Amplitude and phase stability studies in a DC superconducting injector

The DC superconducting injector will be used in the PKU-THz facility which consists of a DC-gun and a 3+1/2-cell superconducting cavity. The cavity must accelerate the electron beam to 5.82 MeV which is susceptible to perturbations because of its narrow bandwidth. In this paper, the sources and influences of the perturbations in the 3+1/2-cell cavity are discussed. It is shown that the control system is essential for the cavity. The design of a feedback based digital RF low level control system for the 3+1/2-cell cavity is accomplished.     

光纤频率调制光谱技术中残余幅度调制特性的研究

频率调制光谱(FMS)技术不仅可以用来同时测量原子和分子的吸收和色散,还是噪声免疫腔增强光外差分子光谱(NICE-OHMS)的关键技术,由于光纤器件的引入或光源输出光的偏振态不稳定等因素会诱发残余幅度调制(RAM),RAM的产生使得FMS技术在痕量气体检测中的应用受到极大的限制,因此研究光纤FMS中RAM的特性具有非常重要的意义。研究首先通过理论分析了无吸收时的FMS信号的线型及RAM的影响因素,实验测量无吸收时输入偏振方向和输出偏振方向及电光调制器(EOM)温度对光纤FMS中RAM的影响,均与RAM存在线型关系,验证了理论分析结果,并为RAM的抑制工作以及基于RAM的其他应用提供了依据。     

Shaping of focal field with controllable amplitude,phase, and polarization

We propose a method for configuring the distribution of amplitude, phase, and polarization in the focal region of vector beams. The polarization and phase of incident beam is spatially tailored so that it can produce a focal field that has elaborately prescribed shapes. Our work focuses on the design of a special focus structure with two oval rings, wherein a phase gradient and polarization gradient exist in the inner and outer rings, respectively. The incident light yielding the desired focal field is determined based on an iterative scheme involving vectorial diffraction calculations and fast Fourier transforms. Simulations and experiments demonstrate the generation of a focal field with phase and polarization gradients, which may find applications in optical manipulation.     

Loaded rubber-like materials subjected to small-amplitude vibrations

This paper proposes a constitutive law and a method for characterizing highly preloaded viscoelastic materials subjected to linear （small-amplitude） vibrations. A multiplicative non-separable variables law has been suggested to model the behavior that depends on both stretch and time/frequency. This approach allows splitting the intricate combined test performed simultaneously on both stretch and frequency, generally in a limited experimental domain up to 100 Hz, into two independent tests. Thus, on one hand, the dynamic complex modulus dependent on frequency alone is evaluated on the basis of vibration tests in a large experimental domain up to 100 kHz. On the other hand, energetic parameters are determined from a quasi-static hyperelastic tensile test. The complex modulus, dependent on both stretch and frequency, is then deduced from the results acquired from uncoupled investigations. This work shows that, in extension, the elastic modulus increases with increasing stretch, and the loss factor decreases with increasing stretch; while, in compression, around the material undeformed state, the modulus increases as the stretch increases till a certain value of compression stretch （upturn point depending on material characteristics）, and then the modulus decreases as the stretch increases. Globally, preload rigidifies materials but reduces their damping property. These results closely match a well-known observation in solid mechanics.