Evidence of self-affine multiplicity fluctuation of target residues in 84Kr-AgBr interactions at 1.7 AGeV

Self-afline multiplicity scaling is investigated in the framework of a two-dimensional factorial mo-ment methodology using the concept of the Hurst exponent (H). Analyzing the experimental data of target evaporated fragments emitted in84Kr-AgBr interactions at 1.7 AGeV revealed that the best power law behav-ior is exhibited for H = 0.3 indicating a self-affine multiplicity fluctuation pattern. A signal of multifractality is also observed from knowledge of the anomalous fractal dimension dq extracted from the intermittency exponent aq of the anisotropic phase space scenario.     

Infrared (IR) image synthesis method of IR real background and modeled IR target

An infrared (IR) image synthesis method is proposed for the synthesis of a real IR background and modeled IR target, used as IR signatures, as well as a band-transformation between short wave IR (SWIR), middle wave IR (MWIR), and long wave IR (LWIR) in an IR imaging system simulation. IR target images are created by the RadThermIR software, an IR signature prediction software. Individual radiances for IR signatures, corresponding to the max/min temperatures of a real IR background and modeled IR target image, are calculated with Planck’s law. First, an IR background of an arbitrary wavelength band is transformed to one of the other wavelength bands with the temperature-radiance characteristics. And then, after adjusting the gray levels of the arbitrary IR target signatures based on their radiances for the wavelength band of the transformed IR background, these IR target and background signatures can be synthesized as one image for a specific wavelength band. The experimental results show that the modeled IR target images, such as a modeled helicopter and F16, can be synthesized on the IR background images of three IR wavelength bands. And we confirmed that IR background images of the three IR wavelength bands can diversely be synthesized with the modeled IR targets as the setting temperature of the target and background, the target distance, and the field of view (FOV) arbitrarily.     

Three-dimensional numerical simulation of drops suspended in simple shear flow at finite Reynolds numbers

A three-dimensional study of suspension of drops in simple shear flow has been performed at finite Reynolds numbers. Results are obtained using a finite difference/front tracking method in a periodic domain. The effects of the Reynolds number and the Capillary number are addressed at two volume fractions: 0.195 and 0.34. It is observed that suspensions of deformable drops exhibit a shear-thinning behavior. Similar to the motion of a single drop, drops migrate away from the walls. The effective viscosity, the first and the second normal stress differences oscillate around a mean value in all cases. The first normal stress difference increases with the Capillary number, the Reynolds number and the volume fraction. Results show that drops deform more and orient more in the flow direction as the Capillary number or the volume fraction is increased. Also, the average size of clusters is smaller than for suspension of rigid particles. The radial dependence of the pair distribution function across the channel has been studied. This dependency shows that the tendency to form clusters is reduced as the Capillary number increases or the volume fraction decreases.     

Tracking problem under a time-varying topology

This paper studies the multi-agent tracking problem of a third-order maneuvering target under uncertain communication environments. Each tracking agent is assumed to be a third-order system and can only use its own and neighbors＇ position, velocity, and acceleration information to design its control input. In this work, the uncertain communication environments are modelled by a finite number of constant Laplacian matrices together with their corresponding scheduling functions. Sufficient conditions for the existence of a tracking strategy have been expressed in terms of the solvability of linear matrix inequalities. Finally, a numerical example is employed to demonstrate the effectiveness of the proposed tracking strategy.     

纹理高阶分形特征在海面舰船目标检测中的应用

针对复杂海面环境下的舰船目标检测，分析了高阶分形特征缝隙在纹理分类中的应用，提出了一种基于分形维与缝隙的目标检测新方法，并利用该方法对海面舰船目标进行了检测。实验结果表明利用纹理分形维与缝隙特征进行海面舰船目标检测，可以取得较单一分形维检测更高的准确率。     

Simple and robust digital holography for high-resolution imaging

Based on the point spread function of holographic system,the lateral resolution of digital holographic imaging system without any pre-magnification is studied.The expression of resolution limitation of holographic imaging system is thus presented.We investigate the possibilities to improve the lateral resolution.The simple experimental setup with an off-axis arrangement is built.By using a U.S.Air Force(USAF)test target as microscopic object,the recorded holograms are reconstructed digitally based on the principle of Fresnel diffraction.The lateral resolution of 2.76 μm without any pre-magnification is demonstrated experimentally,which matches the theoretical prediction well.     

Time resolution of the bunch-shape detector with a thin-wire emission target

The time resolution of a new bunch-length detector based on the radio frequency (RF) scanning of the produced secondary electrons is calculated. A dedicated Monte-Carlo code by means of SIMION software is developed for accurate simulation of spread in the investigated secondary electrons transit times and image width. In calculation the initial energy distribution of electrons and the actual structure of accelerating and focusing electric fields were considered. It is shown that by using a thin-wire emission target a femtosecond time precision could be achieved using moderate applied voltages.     

Simulation on the Effect of Brownian Motion on Nanoparticle Trajectories in a Pulsed Microplasma Cluster Source

We describe a simulation of the nanoparticle trajectories in a pulsed cluster beam source. Clusters, formed by condensation of atomic vapor in a helium bath, and considered here as rigid spheres having a diameter of 1.5nm, were tracked during their travel inside the source cavity, an aerodynamic lens, and a cylindrical nozzle. Steady state supersonic laminar flow of helium is considered in an axi-symmetric geometry aiming to simulate, within some limitations, the conditions under which cluster formation takes place in a pulsed microplasma cluster source. In spite of the unsteady nature of the pulsed source, the time scale characterizing particle motion in the flow field is significantly smaller than the characteristic time constant for the evolution of gas pressure in the source. For this reason, a steady simulation can shed some light on the understanding of processes governing nanoparticle motion in a pulsed vaporization source. The extent to which the Brownian diffusion can affect the particle extraction from the source is investigated. Simulations have shown that the Brownian motion perturbs the clusters from the trajectories dictated by the carrier gas and increases the rate of cluster deposition on the source internal walls. However, it does not hinder the aerodynamic focalization produced by the lens even in nano-size cluster regime. This result is qualitatively confirmed by experiment.     

飞秒激光-薄膜靶相互作用中超热电子产额和激光转化效率

 在激光能量130 mJ（靶面），脉宽60 fs，波长800 nm，对比度1∶10^-6，激光与靶法线成45°夹角，P偏振，靶面激光峰值功率密度约为7.0×10¹⁷ W·cm^-2，无预脉冲的条件下，采用电子谱仪与经γ标准源标定的LiF热释光探测器（TLD）相配合，测量了飞秒激光-薄膜靶相互作用中产生的超热电子能谱。根据所测的能谱，推算出超热电子的产额和激光能量转化为超热电子能量的效率，在靶法线方向分别为1.19×10¹⁰/sr和4.55%/sr，在激光反射方向分别为1.83×10⁹/sr和0.76%/sr。结果显示，不同方向的超热电子产额和激光转化效率有所不同，原因在于激光-等离子体相互作用产生的超热电子构成各向异性的分布。