Fragmentation of 1 GeV/nucleon iron ions in thick targets relevant for space exploration.

We have measured charged nuclear fragments produced by 1 GeV/nucleon 56Fe ions interacting with aluminium, polyethylene and lead. These materials are relevant for assessment of radiation risk for manned space flight. The data will be presented in a form suitable for comparison with models of nuclear fragmentation and transport, including linear energy transfer (LET) spectrum, fluence for iron and fragments, event-tack- and event-dose-averaged LET, total dose and iron contribution to dose.     

A catalogue of low-resolution IUE spectra of dwarf novae and nova-like stars

A catalogue is presented of all the low-resolution IUE spectra of dwarf novae and nova-like stars that were recorded until the end of 1987. All spectra have been reduced, and are displayed, in a homogeneous way. In addition to details about these data, to the extent available, their position in the outburst light curves is given, physical information about each system, and a comprehensive list of references for published observations in all wavelength ranges.In collaboration with Janet A. Mattei, American Association of Variable Star Observers, 25 Birch Street, Cambridge, MA 02138-1205, U.S.A.     

The POKER experiment: A 10,800 cm2 MWPC's array payload for hard X-Ray Astronomy

In this paper the POKER-HXR81M hard X-Ray payload is described. The instrument, designed and built at the Istituto di Astrofisica Spaziale of Frascati, is a very large array of MultiWire Proportional Counters (MWPC) devoted to stratospheric observations of cosmic sources in the field of hard X-Ray Astronomy. The payload basically consists of four passively collimated MWPC's having a geometric sensitive area of 2,700 cm² each with an efficiency higher than 10% in the operative range 15–200 KeV (80% at 60 KeV) with a square field of view of 5° × 5° FWHM. The overall spectral resolution is 13% at 60 KeV. The four MWPC's are filled with a very pure gas mixture of Xenon-Argon-Isobuthane at high pressure (3 bars).This experiment has been successfully flown during summer 1981 from the Milo balloon facility (Sicily, Italy). The performances of the payload and the preliminary results obtained during the 17 hours flight are discussed.     

基于FPGA技术的8位模型机设计与实现

利用EDA技术在FPGA芯片上设计并实现一个简单的8位模型机,主要包括指令系统、运算器、控制器、存储器、时序产生器和总线等设计,在QuartusⅡ6.0集成环境下进行设计、编译和仿真,最后下载到SOPC/EDA实验平台上进行单元和系统测试,达到了设计要求。     

紫外线VS防晒霜

紫外线是肌肤的第一大敌人,会引起衰老、干燥、过敏等众多皮肤问题。因此,在阳光逐渐强烈的夏季,我们一定要做好妥善的防晒措施。除了墨镜、遮阳伞之外,防晒霜也是必不可少的随身物品。     

排毒完全手册

人体需要排毒的原因若胆固醇过高,没有及时排出体外,容易沉积在血管壁上,使血管变窄,导致高血压和动脉硬化等疾病。宿便是人体肠道毒素根源。被重吸收的毒素会重新侵入身体,降低人体免疫力,甚至长期便秘的女性经常会长痘痘。按照自然规律,夏季本是排毒的最佳时机,因为天气炎热,人体会通过大量出汗的方式来排出一年来堆积的毒素。但是现在生活带给我们空调、冷饮、电风扇,使得我们在都市生活中成为"不出汗一族"。没有办法通过自然手段排毒,那么只能自己动手,丰衣足食,用人工手段来排毒了。     

New hard X-rays sources at 38° declination

We report the detection of three new hard X-Rays sources emitting in the range 15 – 150 KeV. Their observation was carried out by means of a balloon borne payload, consisting of two large area high spectral resolution Multiwire Spectroscopic Proportional Counters.     

Effect of Forbush decreases of cosmic ray flux on ozone at higher middle latitudes

The Forbush decreases of cosmic ray flux occur prevailingly together with geomagnetic storms, because these phenomena have a similar origin in solar/interplanetary processes. To study the effects of large Forbush decreases on total ozone at middle latitudes, we use the TOMS total ozone data along latitudinal circles 40°N and 50°N. The effects of Forbush decreases are found to occur or to be non-measurable under the same conditions as those of geomagnetic storms: certain effect occurs only at 50°N (not 40°N), in winter, under conditions of high solar activity and the east phase of the QBO. However, the effects of the analyzed Forbush decreases are weaker than the effects of strong geomagnetic storms.     

Integrated track splitting filter--efficient multi-scan single target tracking in clutter

A fully automatic tracking algorithm must be able to deal with an unknown number of targets, unknown target initiation and termination times, false measurements and possibly time-varying target trajectory behaviour. An efficient algorithm for tracking in this environment is presented here. This approach makes use of estimates of the probability of target existence, which is an integral part of the algorithm. This allows for the efficient generation and management of possible target hypotheses, yielding an algorithm with performance that matches what can be obtained by multiple hypothesis tracking-based approaches, but at a significantly lower computational cost. This paper considers only the single target case for clarity. The extension to multiple targets is easily incorporated into this framework. Simulation studies are given that show the effectiveness of this approach in the presence of heavy and nonuniform clutter when tracking a target in an environment of low probability of detection and in an environment where the target performs violent manoeuvres.