Track structure in polyethylene terephthalate irradiated by heavy ions: Let dependence of track diameter

The structure of latent tracks in polyethylene terephthalate is studied using chemical etching combined with a conductometric technique. Geometrical parameters of the latent tracks for the range of the electronic energy loss (dE/dx) between 3 to 24 keV/nm are estimated. The dependence of the track core and track halo size on the energy loss is analyzed.     

Thermal spike analysis of low energy ion tracks

The theoretical track diameter of low energy ions in organic materials is usually estimated through the model of dose deposition by delta rays, with results remarkably lower than the experimental values obtained via a replica method and electron microscopy. The track detector used here is Makrofol-E and the ions studied have specific energies between 1.4 and 100 keV/n. To evaluate the problem from another point of view, thermal effects for track formation, a modified version of the “liquid drop model” for insulators was applied. The electronic as well as nuclear energy deposition by an individual ion are considered and the thermal spike evolution is studied. The model allows for the formation of ion tracks in a range of energies previously considered as “forbidden”. There still exists a discrepancy between the experimental data and the track diameters predicted by the model, and although this difference is smaller than the obtained with previous calculations, it suggests the necessity of further adjustments.     

串联电解池的创新实验

城市地下输电线路断开后,会与潮湿土壤中处于地上或地下的铁轨(管线)形成回路,加快铁轨(管线)腐蚀。该原理相当于将串联电解池的电解质溶液合并,两池中非连接电源的两电极合为一导体平放于连接电源的两极之间,形成一个特殊的串联电解池。基于以上内容,创新了实验。     

Attenuation of flexural vibration for floating floor and floating box induced by ground vibration

This paper investigates the vibration isolation performance of floating floor and floating box structures to control rail vibration transmission. Simple theoretical and experimental methods are developed to analyze the effects of stiffener beam, mass and arrangement of isolator on the fundamental natural frequency of the flexural vibration of floating floor and box structure.The vibration reduction performances of floating floor and box structure are found to be degraded by flexural vibration of the floor or supporting stiffener beam. From the results of vibration measurements; stiffener beams increase the fundamental natural frequency of flexural vibration of floating floor and enhance vibration isolation. Also they can further alleviate the effect of flexural vibration using optimum isolator arrangement effectively. The proposed floating box design achieved a vibration reduction of 15-30 dB in frequency region of critical rail vibration (30-200 Hz).     

Fission fragment track etching modelling for the cellular localisation of Neptunium-237 nuclei in rat tissues

Heavy ion recording in dielectric isotropic detectors has a wide range of applications in uranium cartography or dating. In this study, solid state nuclear tracks detectors (SSNTDs) have been applied to localise neptunium-237, in vivo, by means of the neutron-induced fission cartography of neptunium-237 nuclei in organ sections. At the cellular level, a precise localisation can only be achieved with a good understanding of the etch pit evolution during the chemical etching process.

A tailor-made software for modelling the etching process has been developed to simulate the profile of an etched track produced by a neutron-induced fission fragment. This software is based on a model that considers the evolution of the track etching velocity along the damage trail in order to perfectly model the shape of the track.     

Analysis of particle methods for structured population models with nonlocal boundary term in the framework of bounded Lipschitz distance

Recently developed theoretical framework for analysis of structured population dynamics in the spaces of nonnegative Radon measures with a suitable metric provides a rigorous tool to study numerical schemes based on particle methods. The approach is based on the idea of tracing growth and transport of measures which approximate the solution of original partial differential equation. In this article, we present analytical and numerical study of two versions of Escalator Boxcar Train algorithm which has been widely applied in theoretical biology, and compare it to the recently developed split‐up algorithm. The novelty of this article is in showing well‐posedness and convergence rates of the schemes using the concept of semiflows on metric spaces. Theoretical results are validated by numerical simulations of test cases, in which distances between simulated and exact solutions are computed using flat metric. © 2014 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 30: 1797–1820, 2014     

Balanced train timetabling on a single-line railway with optimized velocity

This paper aims to find an optimal balanced schedule with the least delay-ratio (i.e., the ratio of the total delay time and the total free-run time) by considering the impacts of the train velocity. A rigorous optimization model is proposed under the consideration of feasible speed constraint for finding the optimal velocity for each train on the railway line. To obtain an approximately optimal scheduling strategy, a combination of the improved TAS (ITAS) method and the genetic algorithm (GA), called GA-ITAS method, is in particular proposed to effectively solve the proposed model. The results of numerical experiments demonstrate the efficiency and effectiveness of the proposed approaches.     

Energy transfer mechanisms on some γ-irradiated synthetic zeolite surfaces

The relation between the amorphization processes in semiconductors under irradiation and the phenomenon of a loss instability in a system of radiation defects has been discussed.     

近圆轨道卫星过顶时间预报的数学模型

基于近圆轨道卫星的特点,通过理论公式推导,确定卫星星下点轨道,建立近圆轨道卫星过顶时间预报的数学模型.首先依据观察站确定卫星进出观察站接收圈时星下点的经纬度,然后根据该点经纬度与卫星倾斜角推求卫星的升交点或者降交点,最后从升交点或者降交点出发外推不超过1/4周期,两者合并得到整个周期的卫星轨迹推导公式.将模型应用于已知和未知卫星轨道根数的实际军事行动避空侦察中去,与实际检测情况相比误差较小、吻合度较高,说明模型有较好的工程应用价值.