用5种不同的电子光学软件对微波管电子枪进行模拟计算

 对TWTCAD微机版、工作站版本、EGUN，CAMEO以及Orprogr电子光学软件背景和特点作了一个简单介绍，并利用其模拟计算了11支不同结构的电子枪。将计算得到的导流系数、射程和注腰半径与实验数据列表对比，结果表明：不同电子光学软件计算不同类型电子枪其计算精度也不一样。在导流系数方面，EGUN和Orprogr的计算精度较高，绝对平均误差分别为7.18%和7.4%；在射程方面，TWTCAD的计算精度最高，绝对平均误差为5.69%；在注腰半径方面，Orprogr与实验值偏差较大，绝对平均误差为47.43%，而工作站版本的计算精度最高，绝对误差仅为2.29%。     

Characterization of smokeless powders using nanoelectrospray ionization mass spectrometry (nESI-MS)

Smokeless powder is one of the most common types of explosives used in civilian ammunition and, hence, its detection and identification is of great forensic value. Based on comparison of physical properties, extraction yield in methanol, and the spectra obtained using nanoelectrospray ionization and multistage tandem mass spectrometry (MS/MS) in a quadrupole ion trap mass spectrometer, a method was developed to identify and differentiate unburned smokeless powders from different brands of ammunition. The mass spectrometry method was optimized for the simultaneous detection of the organic stabilizers commonly present in smokeless powders: methyl centralite, ethyl centralite, and diphenylamine. All but two of the powders were differentiated; however, the two that were not differentiated were produced by the same manufacturer. Gunshot residue from the cartridges was deposited on cotton cloth and collision-induced dissociation MS/MS was used to identify low levels of ethyl centralite in the residue, despite the presence of contaminants.     

Electrochemical Detection of Gunshot Residue for Forensic Analysis: A Review

Current demands for detection of Gunshot Residue (GSR) require a reliable and rapid decentralized detection system with high sensitivity and specificity. This article reviews the use of electrochemical devices for GSR detection over the last 35 years and highlights recent advances associated with the demands of GSR field detection such as portability, speed, cost and power. Anodic stripping voltammetry (ASV) has been widely implemented for the detection of the metallic components of GSR at a variety of working electrodes. Efforts toward the detection of the organic components of GSR have also been reported using cyclic‐ and square‐wave voltammetry. The simultaneous detection of both organic and inorganic GSR constituents has recently been examined to increase the overall information content in a single voltammetric scan. As well as this, exploitation of screen‐printing fabrication allows replacement of conventional electrochemical cells with easy‐to‐use sensor strips Sampling methods for electrochemical GSR analysis are also advancing from acid washes or swabs to simpler abrasive methods which integrate sampling and analysis obviating the need for intermediate processing steps. The latest direction of electrochemical detection of GSR involves chemometric treatment to evaluate data allowing for more objective conclusions and increasing the automation of the system. These advances indicate great promise for investigating firearm‐related crimes, and bring significant changes to the detection of GSR making electroanalysis a powerful tool for decentralized forensic analysis.     

Simultaneous Determination of Antimony and Lead in Gunshot Residue by Cathodic Adsorptive Stripping Voltammetric Methods

Differential pulse cathodic adsorptive stripping (DPCAdSV) and square wave cathodic adsorptive stripping (SWCAdSV) voltammetric methods were developed for the determination of antimony and lead in gunshot residues. Linear working ranges for DPCAdSV and SWCAdSV methods were (2.0×10^?9–5.0×10^?7) M and (2.0×10^?9–7.0×10^?7) M for antimony and 2.0×10^?9–3.0×10^?7 M (both methods) for lead. The detection of antimony limits were found to be 1.3×10^?9 M for DPCAdSV and 7.3×10^?10 M for SWCAdSV while the corresponding values for lead were 3.0×10^?9 M and 5.8×10^?10 M. Antimony and lead contents obtained by these methods in gunshot residues are in good agreement with those obtained by graphite furnace atomic absorption spectrometric method within a confidence limit of 95%.     

Recent developments in methods of chemical analysis in investigations of firearm-related events

A review of recent (approximately the last ten years) developments in the methods used for chemical analysis in investigations of firearm-related events is provided. This review discusses:examination of gunshot (primer) residues (GSR) and gunpowder (propellant) residues on suspects and their clothing;detection of firearm imprints on the hands of suspects;identification of the bullet entry holes and estimation of shooting distance;linking weapons and/or fired ammunition to the gunshot entries, and estimation of the time since discharge.     

Simultaneous determination of inorganic and organic gunshot residues by capillary electrophoresis

A capillary electrophoresis method was developed to analyze simultaneously 11 organic and 10 inorganic components of gunshot residues as a cheaper and possibly more specific method comparing to traditional techniques. Pre-capillary complexation and simultaneously a micellar phase were combined to determine not only the metal but also the organic residues from a firearm. In order to test the possibility to apply the developed method to real cases, residues from shot samples from different firearms were analyzed and their results were compared with those obtained with electrothermal atomic absorption spectroscopy, an established technique for gunshot residue analysis. Good agreement between both techniques for lead was found.     

Fast Mapping of Gunshot Residues by Batch Injection Analysis with Anodic Stripping Voltammetry of Lead at the Hanging Mercury Drop Electrode

The forensic analysis of lead in gunshot residues (GSR) sampled on the hands of potential shooters is rendered faster, simpler and less expensive by a new batch injection analysis (BIA) method, based on differential pulse anodic stripping voltammetry (DPASV). A simple “J” shaped adaptor was designed to direct the flux of the analyte injected with a micropipettor onto the hanging mercury drop electrode of any commercial electrode stand. Sampling methods for GSR were compared and lifting with adhesive tape was elected for field use. The tapes are glued on polyethylene screens and stored in capped vials. Sampling with multiple strips provides coarse mapping of the distribution of lead on the shooter's hands. After a dissolution/extraction step with chloroform/aqueous 0.10 mol L^?1 HCl, 100 μL of the aqueous phase are injected during 25 s for accumulation of lead on the HMDE at ?0.60 V (vs. Ag/AgCl). A detection limit of 20 ng/mL of Pb(II), outreaching for GSR analysis, is reached without oxygen removal, at a frequency of 20 injections per hour. Results for sequences of shootings with a revolver and a pistol are presented.     

基于大能量火花放电的枪声模拟系统设计*

为准确模拟某型枪械实弹射击枪声,设计了一种基于大能量火花放电的枪声模拟系统,理论分析和仿真验证了系统工作原理,并对所模拟枪声的声级以及时域和频域特性进行了试验测试。仿真和测试结果表明:点火电容放电所辐射的电场击穿高能电极空气间隙,可有效控制储能电容组火花放电模拟枪声;模拟与真实枪声的声级误差约为-2.1~5.8 d B(A),标准差为1.974 dB(A),模拟与真实枪声的时域信号随时间增加均以指数形式迅速减小且频谱分布规律一致;模拟与真实枪声信号在时域进行相关运算后存在着明显的相关峰,二者有较好的相似性。