Track Extensions of Categories and Cohomology

We introduce the notion of n-fold track extensions of a category C by a natural system D and prove that such extensions represent classes in the cohomology of C with coefficients in D introduced by Baues–Wirsching. This generalizes a result of Huebschmann on the cohomology of groups.     

Designing polymers for nuclear track detection

This article describes our attempts since 1996 to systematically design and synthesize monomers and corresponding polymers for nuclear track detection. So far more than 15 homopolymers/copolymers have been prepared and tested by us for this purpose. Some of these polymers show better track detection characteristics vis-á-vis commercially available poly allyl diglycol carbonate (PADC) track detectors.      

Spatial structure and energy spectrum of ion beams studied with CN detectors within a small PF device

The paper reports the application of Solid-State Nuclear Track Detectors to study the pulsed plasma-ion streams emitted from plasma-focus (PF) type discharges, which were performed within a low-energy PACO device constructed at Instituto de Fisica Arroyo Seco. The PACO device was operated under static initial gas conditions or with dynamic gas puffing. Studies of the structure of the fast deuteron beams were carried out within an energy range from 80 keV to about 2 MeV. Studies of ion energy and an ion angular distribution were also performed. The measurements showed that the fast deuterons are emitted in many “narrow” micro-beams, as in other larger PF devices. The anisotropy of the deuteron angular distribution was explained by the stochastic character of the formation of local ion sources within the PF discharge column.     

Frequency– and Time-domain BEM Analysis of Rigid Track on a Half-Space with Vibration Barriers

The rapid development of high-speed trains like the TGV or the ICE in recent years results in high dynamic loads causing vibrations which propagate from the train-track structure into the ground and further into nearby buildings. In this context it is important to develop rigid tracks with improved dynamic behaviour and to investigate possible means of vibration reduction. The boundary element method in frequency and time domain is used to simulate train-track structures subjected to dynamic loading and the reduction of vibrations which for instance can be achieved via a trench running parallel to the rigid track. In this context the non-causality error, which arises when the time-domain BEM algorithm is applied to mathematically concave domains, is discussed and the substructure method is proposed as a solution to this problem. A two-layered cylindrical elastic structure on a half-space with a trench is added as an example of a possible application.     

pH‐induced on–off switching of polycarbonate track‐etched membranes by plasma‐induced surface grafting

Surface functionalization of the plasma‐pretreated polycarbonate (PC) track‐etched membranes via plasma‐induced thermally graft copolymerization of acrylic acid (AAc) was carried out. The resulting PC membranes with grafted AAc side chains were characterized by X‐ray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR) spectroscopy, and thermogravimetric (TG) analysis. The morphology of the PC membranes was studied by scanning electron microscopy (SEM). The results showed that the grafted PAAc polymers were formed uniformly inside the pores throughout the entire membrane thickness. With increase in the pore‐filling ratio, the pore diameters of PAAc‐grafted membranes became smaller. The PC‐g‐PAAc membranes exhibit rapid and reversible response of the flux to the environmental pH as pH is switched between 3 and 9. Between pH 3.5 and 5.5, the membranes demonstrate a pH‐valve function as the carboxyl group changes from neutral to charged with a corresponding variation in chain configuration. Copyright © 2009 John Wiley & Sons, Ltd.     

用DIS位移传感器研究气垫导轨上的阻尼振动

在简述阻尼振动实验原理的基础上,阐述了用DIS位移传感器研究气垫导轨上阻尼振动的方法,通过对比实验进一步论述了该方法的可行性.     

两轴光电跟踪仪高仰角跟踪盲区分析

 从轴准直误差、动态滞后误差两方面分析了采用俯仰轴叠加于方位轴光机座结构方式的光电跟踪仪在高俯仰角跟踪时的误差变化及由此导致的盲区问题,从轴准直误差和动态滞后误差两方面对高仰角跟踪盲区的形成及其空间分布进行分析,并用MATLAB进行了仿真,给出跟踪盲区随方位、俯仰角变化的的分布图形。从盲区分布图形可以看出：光电跟踪仪在性能一定的情况下,跟踪盲区随着仰角增大而增大,并结合直线航路给出这两种误差导致的跟踪盲区的计算方法。跟踪直线航路实验数据显示跟踪误差随着仰角增大而增大。     

红外凝视系统下的多规则航迹起始算法

针对传统航迹起始算法在红外凝视跟踪系统应用中存在的弊端,提出了一种适用于凝视跟踪系统的多规则快速航迹起始算法.该方法通过深入分析红外凝视系统中目标自身特点及其运动特性,给出了能够对低速甚至静止的大威胁概率目标和断续点迹目标进行威胁概率判断和航向方差判断的起始规则,实现了凝视系统下对大威胁概率目标和断续点迹目标航迹的快速...     

Ageing of AgCl/Cd nuclear track detectors monitored by luminescence spectroscopy

Abstract

Solid-state nuclear track detectors, made of Cd doped AgCl crystals, are commonly prepared by rolling into the form of thin foils. Subsequent long-term relaxation is however needed to obtain good quality tracks. The present communication shows for the first time that this detector “ageing” is reflected in lowtemperature (77 K) luminescence spectra. Maximum of the emission band shows a slow (lasting for ～ 100 hours) blue shift, the magnitude of which (as much as 25 nm) depends on the compression ratio caused by the rolling. The shift is believed to be due to the rearrangement of Cd⁺⁺ ions around freshly introduced dislocations. This finding opens the possibility of monitoring non-destructively the process of detector ageing and to determine the minimum time required for saturation.     

Beam profile measurement with CR-39 track detector for low-energy ions

A CR-39 track detector was successfully used to measure the outline of thin low-energy ion beams. After the etching, the surface of the detector was examined with an observation system composed of a Normarski microscope, a CCD camera and a digital image processing computer. Beam images obtained with the system were in good agreement on the outline of the beam formed with a beam aperture. Also, the resolving power in the beam outline measurement was roughly explained from the consideration of the ion range and the etch-pit growth in the chemical etching for the CR-39 detector.