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1.
Questioned documents examined in a forensic laboratory sometimes contain signatures written with ballpoint pen inks; these signatures were examined to assess the feasibility of micro‐attenuated total reflectance (ATR) Fourier transform infrared (FTIR) spectroscopy as a forensic tool. Micro‐ATR FTIR spectra for signatures written with 63 ballpoint pens available commercially in Korea were obtained and used to construct an FTIR spectral database. A library‐searching program was utilized to identify the manufacturer, blend, and model of each black ballpoint pen ink based upon their FTIR peak intensities, positions, and patterns in the spectral database. This FTIR technique was also successfully used in determining the sequence of homogeneous line intersections from the crossing lines of two ballpoint pen signatures. We have demonstrated with a set of sample documents that micro‐ATR FTIR is a viable nondestructive analytical method that can be used to identify the origin of the ballpoint pen ink used to mark signatures.  相似文献   

2.
Abstract: Camouflage garments can be associated with surveillance images of a crime scene even in the absence of unique wear marks or very high‐quality images. However, the probability of an accidental association, or incidence rate, is significant. The present work describes and validates a method for estimating the incidence rate based on a statistical model of the garment manufacturing process. The model was developed primarily for use with the current U.S. Army Combat Uniform (ACU), but can be applied to any camouflage garment. Eight garment manufacturers were studied, and all sources of variation in the manufacturing process were characterized. The marking and spreading procedures were found to be dominant and consistent sources of variation. However, some sources of variation, in particular those because of human operators, were not consistent enough to accurately characterize. Sources of variation that could not be well‐characterized were ignored in the statistical model, yielding a worst‐case estimate that is an upper‐bound to the true incidence rate. The model was evaluated for a variety of cases. Depending on the quality of the surveillance image, the manufacturing parameters, and the local population, incidence rates range from about 3% to negligibly small. The model was validated by returning to one manufacturer, and sampling a large number of completed garments and estimating empirical match probabilities. The empirical probabilities validated the estimates of the worst‐case incidence rate and also demonstrated that typical incidence rates are significantly lower.  相似文献   

3.
利用激光刻章机雕刻、光敏印章机制印伪造印章印文是近年来出现的一种新的、仿真程度较高的伪造印章印文的方法。鉴定实践表明,这类伪造印章印文趋于专业化、技术化,且伪造的印章印文与真实印章印文的相似度较高。依据传统的鉴定依据和方法难以鉴别真伪,因此从该类伪造方法对其特点和鉴定依据、方法要点进行研究,尤其是对伪造形成方式及特点的研究,有助于科学的鉴定其真伪。  相似文献   

4.
Plastic bottles are commonly encountered in drug cases where they are used as packaging materials and produced with polymers. However, to the best of our knowledge, systematic studies on the evidential values of medicine bottles have not been carried out. Therefore, it is difficult practically to determine if it is possible to identify whether the plastic bottles are manufactured with the same steel mold by comparing the manufacturing marks on plastic bottles. This paper reports the successful attempt of the authors in establishing a definite relationship between three different medicine bottles with a steel mold recovered from suspects. Fourier transform infrared spectroscopy (FT-IR) was used to characterize the chemical composition of submitted medicine bottles, and then some physical characteristics (viz., total length, length, and diameter of different parts) and the manufactured marks on these bottles were examined. The results showed that the linkage of the medicine bottles to a steel mold was successfully established using the similarities in physical characteristics and manufacturing marks. In the process, the FT-IR was only complementary in the identification process. The individual characteristics of plastic medicine bottles included the imperfections and striated impressions that were produced by the grinding patterns on the inner surface of a steel mold.  相似文献   

5.
Abstract:  The illicit manufacture of heroin results in the formation of trace level acidic and neutral impurities. These impurities are detectable in illicit heroin and provide valuable information about the manufacturing process used. The isolation, derivatization, and semiquantitative analysis of neutral and acidic heroin manufacturing impurities by programmed temperature vaporizing injector-gas chromatography-mass spectrometry (PTV-GC-MS) is described. Trace acidic and neutral heroin impurities were isolated from basic fractions using liquid–liquid extraction. Extracted impurities were treated with N -Methyl- N -trimethylsilyltrifluoroacetamide followed by PTV-GC-MS analyses. Semiquantitative data were obtained using full scan mass spectrometry utilizing unique ions or ion combinations for 36 trace impurities found in crude and/or highly refined heroin samples. Minimum detection limits for acidic and neutral impurities were estimated to be at the 10−7 level relative to total morphine. Over 500 authentic heroin samples from South America, Mexico, Southwest Asia, and Southeast Asia were analyzed. Classification of illicit heroin based on the presence or absence and relative amounts of acidic and neutral impurities is presented.  相似文献   

6.
OEM (large firm) supplier-development programs have expanded from a quality focus to include more technologically sophisticated issues. The quality issues now require the supplier to supply functional sub-assemblies as well as discrete parts and to insure the capability of second- and third-tier vendors. In addition, the supplier must be prepared to participate in the design of a new product in a timely fashion in the case where the supplier may possess core manufacturing technologies that the OEM needs to complete the design cycle. The Northeast Manufacturing Technology Center (NEMTC) is developing a multistage evaluation and assessment process that will allow a small manufacturer to measure its business and technical capabilities against accepted benchmarks (such as ISO 9000). This development is being funded by a grant from the State of New York. Coincidentally, NEMTC is working with 31 OEMs to match their supplierassessment programs to the same benchmarks. This will allow the OEM and the small manufacturer to determine their compatibility. The program will be coupled with a support program that will bring the small manufacturer up to the desired performance level through the transfer of the appropriate technologies. It will allow NEMTC to target its program to small manufacturers with the potential to become vendors to OEMs. The center is supported by the National Institute of Standards and Technology.  相似文献   

7.
A trace code pattern location measurement approach is proposed. It includes a method that can precisely extract the trace code pattern to identify the color laser printer or photocopier class. In this study, we collected 379 samples from 15 brands, including 129 models and 196 printers or photocopiers. The trace code pattern class is identified. Four class characteristics are used to identify the print source: (i) the relation between the pattern and print output direction; (ii) observation of the shape features from among the trace code pattern units; (iii) the feature arrangement from among the trace code pattern units; and (iv) the arrangement relation of the trace code pattern. Blind testing shows that the accuracy of the proposed method is approximately 96.9% for the Questioned Document Examiners, and 84.3% in the non‐Questioned Document Examiners. It is thus an effective technique for determining a print's color laser printer or photocopier source class.  相似文献   

8.
Multiple analytical techniques for the screening of fentanyl-related compounds exist. High discriminatory methods such as GC–MS and LC–MS are expensive, time-consuming, and less amenable to onsite analysis. Raman spectroscopy provides a rapid, inexpensive alternative. Raman variants such as electrochemical surface-enhanced Raman scattering (EC-SERS) can provide signal enhancements with 1010 magnitudes, allowing for the detection of low-concentration analytes, otherwise undetected using conventional Raman. Library search algorithms embedded in instruments utilizing SERS may suffer from accuracy when multicomponent mixtures involving fentanyl derivatives are analyzed. The complexing of machine learning techniques to Raman spectra demonstrates an improvement in the discrimination of drugs even when present in multicomponent mixtures of various ratios. Additionally, these algorithms are capable of identifying spectral features difficult to detect by manual comparisons. Therefore, the goal of this study was to evaluate fentanyl-related compounds and other drugs of abuse using EC-SERS and to process the acquired data using machine learning—convolutional neural networks (CNN). The CNN was created using Keras v 2.4.0 with Tensorflow v 2.9.1 backend. In-house binary mixtures and authentic adjudicated case samples were used to evaluate the created machine-learning models. The overall accuracy of the model was 98.4 ± 0.1% after 10-fold cross-validation. The correct identification for the in-house binary mixtures was 92%, while the authentic case samples were 85%. The high accuracies achieved in this study demonstrate the advantage of using machine learning to process spectral data when screening seized drug materials comprised of multiple components.  相似文献   

9.
自动驾驶汽车是人类研发、制造、使用和管理的智能产品,不是犯罪主体或刑事责任主体。在自动驾驶汽车自主控制状态下发生交通事故的,其生产者、使用者和其他人员难以按照我国现有刑法的罪名定罪处罚。除非道路交通安全法和刑法有专门的规定,驾驶位人员不接管汽车或接管后无力改变交通事故结果的,不构成交通肇事罪或其他管理过失犯罪。驾驶位人员的注意义务是阻止自动驾驶汽车自主控制下发生交通事故,其注意义务不应过高。允许的风险、紧急避险理论不能为自动驾驶汽车紧急路况处理算法的生产与应用提供合法、合理的解决方案,生产者遵守算法安全标准仅可以使生产行为合法化。鉴于现行刑法不适应自动驾驶汽车应用的特性,我国应当建立以生产者全程负责为中心的新刑事责任体系,使之在自动驾驶汽车生产和应用两个阶段承担安全管理责任,生产者拒不履行自动驾驶汽车应用安全管理义务且情节严重的,应当承担刑事责任。  相似文献   

10.
Fourier-transform infrared spectroscopy (FTIR), discriminate analysis, X-ray fluorescence spectrometry (XRF), and stereoscopic microscopy were used to separate black coral forensic evidence items from similarly appearing items manufactured from plastics, bovid keratin, and mangrove wood. In addition, novel observations were made of bromine and iodine relationships in black coral that have not been previously reported.  相似文献   

11.
In forensic DNA profiling use is made of the well-known technique of PCR. When the amount of DNA is high, generally unambiguous profiles can be obtained, but for low copy number DNA stochastic effects can play a major role. In order to shed light on these stochastic effects, we present a simple model for the amplification process. According to the model, three possible things can happen to an individual single DNA strand in each complete cycle: successful amplification, no amplification, or amplification with the introduction of stutter. The model is developed in mathematical terms using a recursive approach: given the numbers of chains at a given cycle, the numbers in the next can be described using a multinomial probability distribution. A full set of recursive relations is derived for the expectations and (co)variances of the number of amplicon chains with no, 1 or 2 stutters. The exact mathematical solutions of this set are given, revealing the development of the expectations and (co)variances as function of the cycle number. The equations reveal that the expected number of amplicon chains without stutter grows exponentially with the cycle number, but for the chains with stutter the relation is more complex. The relative standard deviation on the numbers of chains (coefficient of variation) is inversely proportional to the square root of the expected number of DNA strands entering the amplification. As such, for high copy number DNA the stochastic effects can be ignored, but they play an important role at low concentrations. For the allelic peak, the coefficient of variation rapidly stabilizes after a few cycles, but for the chains with stutter the decrease is more slowly. Further, the ratio of the expected intensity of the stutter peak over that of the allelic peak increases linearly with the number of cycles. Stochastic models, like the one developed in the current paper, can be important in further developing interpretation rules in a Bayesian context.  相似文献   

12.
目的 以方言语音学为视角,通过计算机分析和选择模型训练数据,探究提高口音自动识别准确率及优化模型训练数据的方法.方法 采用音系分析、语音信号处理、数学模型实验和统计的方法,对包含约81400段电子语音的37个方言点(每个方言点约2200段),逐一进行音系提炼、挑选音系例字、电子语音预处理和提取梅尔倒谱系数(MFCC),...  相似文献   

13.
Abstract

In the course of a trial, the main task that every judge or juror has to face concerns the evaluation of various pieces of evidence from a variety of different sources, with the aim of integrating such data into a single, final verdict. Algebraic models have tried to explain and predict decisional paths by identifying formal, mathematical combinatory rules. The aim of the present research was to test two main integration information models, namely adding and averaging, when combining items of judicial evidence. In the first study, we investigated how the probability of guilt varied as a function of the value of the pieces of evidence and information presented, in legal and not legal professional samples. In the second study, we analysed combinatory rules with more complex and realistic experimental material. Results indicated that participants summed the values of pieces of evidence in a linear fashion when they had to provide estimates of guilt. We found evidence of an adding rule among both legal and not legal professionals as well as in simple and more complex judicial cases, thus providing even stronger support for the use and the generalization of a summative model. Theoretical and practical implications are discussed.  相似文献   

14.
《法医学杂志》2018,(2):161-164
Objective: To validate the analysis capability of RapidHITTM 200 system for four kinds of routine forensic samples and the recyclable capability of template, template DNA and PCR products in the process of twice duplicate detection. Methods: The buccal swabs underwent the test twice by RapidHITTM 200 system, and the template DNA and PCR products that arose in the system were also tested for two times. After four kinds of routine forensic samples were detected by RapidHITTM 200 system, the follow- up tests of the template, template DNA and PCR products that arose in the system were performed. Results: The STR loci could be detected in the buccal swabs by the system for the first time. However, part of the STR loci lost during the second test. And the peak value obtained in the second test was significantly reduced than the one in the first time. The average STR loci detection rates of the template DNA and PCR products were both less than 50% in the second test, which were significantly reduced than that in the first test. In addition, the analysis capability of the system for the tissues and buccal swabs was better than that for the blood and cigarette butts. Compared with the first test, the STR loci detection rate of the tested items, template DNA and PCR products decreased with the numbers of tests. Conclusion: RapidHITTM 200 system is more effective in retesting buccal swabs than other samples, whereas the items, DNA template, PCR products obtained in the first and second time cannot be directly used for the further application and study of forensic medicine. © 2018 by the Editorial Department of Journal of Forensic Medicine.  相似文献   

15.
A validated gas chromatographic-mass spectrometric method for quantitative analysis of methaqualone (MTQ) in illicit preparations is reported. The method proved to have a coefficient of variation of below 5%. Four batches of seized tablets, two pairs with similar imprints, were analyzed. It was found that the average MTQ concentration in all four batches of tablets differed significantly (p = 0.01) rendering it impossible to conclude that, on the basis of MTQ concentration alone, the batches with a similar logo originated from the same manufacturer or manufacturing batch. Conversely, it can be said that in this case, the four batches originated from either different clandestine laboratories or manufacturing batches.  相似文献   

16.
电子数据司法鉴定已经成为当前司法鉴定研究热点问题之一。它是计算机司法鉴定的一种主要类型。根据鉴定性质不同,电子数据司法鉴定可以分为以“发现证据”为目标的鉴定和以“评估证据”为目标的鉴定。前者包括数据检索与固定、数据恢复、数据来源分析、数据内容分析、数据综合分析;后者包括同一鉴定、真伪鉴定、相似性鉴定、功能鉴定、复合鉴定等不同性质的鉴定项目。这两类鉴定在鉴定目标、程序、风险、意见主观性和证据审查等方面均存在显著差异。  相似文献   

17.
Score-based approaches for computing forensic likelihood ratios are becoming more prevalent in the forensic literature. When two items of evidential value are entangled via a scorefunction, several nuances arise when attempting to model the score behavior under the competing source-level propositions. Specific assumptions must be made in order to appropriately model the numerator and denominator probability distributions. This process is fairly straightforward for the numerator of the score-based likelihood ratio, entailing the generation of a database of scores obtained by pairing items of evidence from the same source. However, this process presents ambiguities for the denominator database generation - in particular, how best to generate a database of scores between two items of different sources. Many alternatives have appeared in the literature, three of which we will consider in detail. They differ in their approach to generating denominator databases, by pairing (1) the item of known source with randomly selected items from a relevant database; (2) the item of unknown source with randomly generated items from a relevant database; or (3) two randomly generated items. When the two items differ in type, perhaps one having higher information content, these three alternatives can produce very different denominator databases. While each of these alternatives has appeared in the literature, the decision of how to generate the denominator database is often made without calling attention to the subjective nature of this process. In this paper, we compare each of the three methods (and the resulting score-based likelihood ratios), which can be thought of as three distinct interpretations of the denominator proposition. Our goal in performing these comparisons is to illustrate the effect that subtle modifications of these propositions can have on inferences drawn from the evidence evaluation procedure. The study was performed using a data set composed of cursive writing samples from over 400 writers. We found that, when provided with the same two items of evidence, the three methods often would lead to differing conclusions (with rates of disagreement ranging from 0.005 to 0.48). Rates of misleading evidence and Tippet plots are both used to characterize the range of behavior for the methods over varying sized questioned documents. The appendix shows that the three score-based likelihood ratios are theoretically very different not only from each other, but also from the likelihood ratio, and as a consequence each display drastically different behavior.  相似文献   

18.
The melting behavior of 28 high density polyethylene (HDPE) pipe samples manufactured and supplied by 13 different manufacturers in India was examined by 'differential scanning calorimetry (DSC)' to find out if this parameter could be used in differentiating between these HDPE pipe samples which are chemically the same and being manufactured by different manufacturer. The results indicate that the melting temperature may serve as the useful criteria for differentiating HDPE (i) pipe samples from different sources and (ii) samples of different diameter from the same source.  相似文献   

19.
Exploring Some Analytical Characteristics of Finite Mixture Models   总被引:1,自引:0,他引:1  
Finite mixture models have become increasingly prevalent in criminology over the past two decades. Yet there is no consensus about the appropriate criterion for model selection with finite mixture specifications. In this paper, we use simulation evidence to examine model selection criteria. Our focus is on mixture models for event count data like those often encountered in criminology. We use two indices to measure model selection performance. First, we examine how often each criterion chooses the correct specification. Then, we investigate how closely the finite mixture models selected by these criteria approximate the true mixing distribution used to simulate the event count data. We consider three sets of simulations. In the first set, the underlying model is itself a three component Poisson-based finite mixture model. In the two other sets of simulations, the underlying distribution of the Poisson rate parameter follows a continuous distribution. The analysis shows that both AIC and BIC perform well under certain sets of circumstances likely to be encountered by criminologists.
Daniel S. NaginEmail:
  相似文献   

20.
This paper investigates whether firms innovate persistently or discontinuously over time using an innovation panel data set on German manufacturing and service firms for the period 1994–2002. It turns out that innovation behaviour is permanent at the firm level to a very large extent. Using a dynamic random effects discrete choice model and a new estimator recently proposed by Wooldridge (2005), I further shed some light on the driving forces for this phenomenon. The econometric results show that past innovation experience is an important determinant for manufacturing as well as for service sector firms, and hence confirm the hypothesis of true state dependence. In addition, the results highlight the important role of knowledge provided by skilled employees and unobserved individual heterogeneity in explaining the persistence of innovation.
Bettina PetersEmail:
  相似文献   

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