144 research outputs found

    Currency security and forensics: a survey

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    By its definition, the word currency refers to an agreed medium for exchange, a nation’s currency is the formal medium enforced by the elected governing entity. Throughout history, issuers have faced one common threat: counterfeiting. Despite technological advancements, overcoming counterfeit production remains a distant future. Scientific determination of authenticity requires a deep understanding of the raw materials and manufacturing processes involved. This survey serves as a synthesis of the current literature to understand the technology and the mechanics involved in currency manufacture and security, whilst identifying gaps in the current literature. Ultimately, a robust currency is desire

    An experimental study on the deformation behaviour and fracture mode of recycled aluminium alloy AA6061-reinforced alumina oxide undergoing high-velocity impact

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    The anisotropic behaviour and the damage evolution of recycled aluminium alloy-reinforced alumina oxide are investigated in this paper using Taylor impact test. The test is performed at various impact velocity ranging from 190 to 360 m/s by firing a cylindrical projectile towards anvil target. The deformation behaviour and the fracture modes are analysed using the digitized footprint of the deformed specimens. The damage initiation and the progression are observed around the impact surface and the surface 0.5 cm from the impact area using the scanning electron microscope. The deformed specimens showed several ductile fracture modes of mushrooming, tensile splitting and petalling. The critical impact velocity is defined below 280 m/s. The specimens showed a strong strain-rate dependency due to the damage evolution that is driven by severe localized plastic-strain deformation. The scanning electron microscope analysis showed the damage mechanism progress via voids initiation, growth and coalescence in the material. The micrograph within the footprint surface shows the presence of alumina oxide particles within the specimen. The microstructure analysis shows a significant refinement of the specimen particle at the surface located 0.5 cm above the impact area. ImageJ software is adopted in this work to measure the average size of voids within this surface. Non-symmetrical (ellipse-shaped) footprint around the footprints showed plastic anisotropic behaviour. The results in this paper provide a better understanding of the deformation behaviour of recycled materials subjected to dynamic loading. This information on mechanical response is crucial before any potential application can be established to substitute the primary sources

    Biometric Systems

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    Biometric authentication has been widely used for access control and security systems over the past few years. The purpose of this book is to provide the readers with life cycle of different biometric authentication systems from their design and development to qualification and final application. The major systems discussed in this book include fingerprint identification, face recognition, iris segmentation and classification, signature verification and other miscellaneous systems which describe management policies of biometrics, reliability measures, pressure based typing and signature verification, bio-chemical systems and behavioral characteristics. In summary, this book provides the students and the researchers with different approaches to develop biometric authentication systems and at the same time includes state-of-the-art approaches in their design and development. The approaches have been thoroughly tested on standard databases and in real world applications

    Content Recognition and Context Modeling for Document Analysis and Retrieval

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    The nature and scope of available documents are changing significantly in many areas of document analysis and retrieval as complex, heterogeneous collections become accessible to virtually everyone via the web. The increasing level of diversity presents a great challenge for document image content categorization, indexing, and retrieval. Meanwhile, the processing of documents with unconstrained layouts and complex formatting often requires effective leveraging of broad contextual knowledge. In this dissertation, we first present a novel approach for document image content categorization, using a lexicon of shape features. Each lexical word corresponds to a scale and rotation invariant local shape feature that is generic enough to be detected repeatably and is segmentation free. A concise, structurally indexed shape lexicon is learned by clustering and partitioning feature types through graph cuts. Our idea finds successful application in several challenging tasks, including content recognition of diverse web images and language identification on documents composed of mixed machine printed text and handwriting. Second, we address two fundamental problems in signature-based document image retrieval. Facing continually increasing volumes of documents, detecting and recognizing unique, evidentiary visual entities (\eg, signatures and logos) provides a practical and reliable supplement to the OCR recognition of printed text. We propose a novel multi-scale framework to detect and segment signatures jointly from document images, based on the structural saliency under a signature production model. We formulate the problem of signature retrieval in the unconstrained setting of geometry-invariant deformable shape matching and demonstrate state-of-the-art performance in signature matching and verification. Third, we present a model-based approach for extracting relevant named entities from unstructured documents. In a wide range of applications that require structured information from diverse, unstructured document images, processing OCR text does not give satisfactory results due to the absence of linguistic context. Our approach enables learning of inference rules collectively based on contextual information from both page layout and text features. Finally, we demonstrate the importance of mining general web user behavior data for improving document ranking and other web search experience. The context of web user activities reveals their preferences and intents, and we emphasize the analysis of individual user sessions for creating aggregate models. We introduce a novel algorithm for estimating web page and web site importance, and discuss its theoretical foundation based on an intentional surfer model. We demonstrate that our approach significantly improves large-scale document retrieval performance

    Multibiometric security in wireless communication systems

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    This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University, 05/08/2010.This thesis has aimed to explore an application of Multibiometrics to secured wireless communications. The medium of study for this purpose included Wi-Fi, 3G, and WiMAX, over which simulations and experimental studies were carried out to assess the performance. In specific, restriction of access to authorized users only is provided by a technique referred to hereafter as multibiometric cryptosystem. In brief, the system is built upon a complete challenge/response methodology in order to obtain a high level of security on the basis of user identification by fingerprint and further confirmation by verification of the user through text-dependent speaker recognition. First is the enrolment phase by which the database of watermarked fingerprints with memorable texts along with the voice features, based on the same texts, is created by sending them to the server through wireless channel. Later is the verification stage at which claimed users, ones who claim are genuine, are verified against the database, and it consists of five steps. Initially faced by the identification level, one is asked to first present one’s fingerprint and a memorable word, former is watermarked into latter, in order for system to authenticate the fingerprint and verify the validity of it by retrieving the challenge for accepted user. The following three steps then involve speaker recognition including the user responding to the challenge by text-dependent voice, server authenticating the response, and finally server accepting/rejecting the user. In order to implement fingerprint watermarking, i.e. incorporating the memorable word as a watermark message into the fingerprint image, an algorithm of five steps has been developed. The first three novel steps having to do with the fingerprint image enhancement (CLAHE with 'Clip Limit', standard deviation analysis and sliding neighborhood) have been followed with further two steps for embedding, and extracting the watermark into the enhanced fingerprint image utilising Discrete Wavelet Transform (DWT). In the speaker recognition stage, the limitations of this technique in wireless communication have been addressed by sending voice feature (cepstral coefficients) instead of raw sample. This scheme is to reap the advantages of reducing the transmission time and dependency of the data on communication channel, together with no loss of packet. Finally, the obtained results have verified the claims

    Verification of Authenticity of Stamps in Documents

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    KlasickĂĄ inkoustovĂĄ razĂ­tka, kterĂĄ se pouĆŸĂ­vajĂ­ k autorizaci dokumentĆŻ, se dnes dĂ­ky rozơíƙenĂ­ modernĂ­ch technologiĂ­ dajĂ­ relativně snadno padělat metodou oskenovĂĄnĂ­ a vytiĆĄtěnĂ­. V rĂĄmci diplomovĂ© prĂĄce je vyvĂ­jen automatickĂœ nĂĄstroj pro ověƙenĂ­ pravosti razĂ­tek, kterĂœ najde vyuĆŸitĂ­ zejmĂ©na v prostƙedĂ­ch, kde je nutnĂ© zpracovĂĄvat velkĂ© mnoĆŸstvĂ­ dokumentĆŻ. Procesu ověƙenĂ­ pravosti razĂ­tka musĂ­ pƙirozeně pƙedchĂĄzet jeho detekce v dokumentu - Ășloha zpracovĂĄnĂ­ obrazu, kterĂĄ zatĂ­m nemĂĄ pƙesvědčivĂ© ƙeĆĄenĂ­. V tĂ©to diplomovĂ© prĂĄci je navrĆŸena zcela novĂĄ metoda detekce a ověƙenĂ­ pravosti razĂ­tka v barevnĂœch obrazech dokumentĆŻ. Tato metoda zahrnuje plnou segmentaci strĂĄnky za Ășčelem určenĂ­ kandidĂĄtnĂ­ch ƙeĆĄenĂ­, dĂĄle extrakci pƙíznakĆŻ a nĂĄslednou klasifikaci kandidĂĄtĆŻ za pomoci algoritmu podpĆŻrnĂœch vektorĆŻ (SVM). Evaluace ukĂĄzala, ĆŸe algoritmus umoĆŸĆˆuje rozliĆĄovat razĂ­tka od jinĂœch barevnĂœch objektĆŻ v dokumentu jako jsou napƙíklad loga a barevnĂ© nĂĄpisy. Kromě toho algoritmus dokĂĄĆŸe rozliĆĄit pravĂĄ razĂ­tka od kopiĂ­.Classical ink stamps and seals used for authentication of a document content have become relatively easy to forge by the scan & print technique since the technology is available to general public. For environments where a huge volume of documents is processed, an automatic system for verification of authenticity of stamps is being developed in the scope of this master's thesis. The process of stamp authenticity verification naturally must be preceded by the phase of stamp detection and segmentation - a difficult task of Document Image Analysis (DIA). In this master's thesis, a novel method for detection and verification of stamps in color document images is proposed. It involves a full segmentation of the page to identify candidate solutions, extraction of features, and further classification of the candidates by means of support vector machines. The evaluation has shown that the algorithm is capable of differentiating stamps from other color objects in the document such as logos or text and also genuine stamps from copied ones.

    Digital analysis of paintings

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    Biometrics

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    Biometrics uses methods for unique recognition of humans based upon one or more intrinsic physical or behavioral traits. In computer science, particularly, biometrics is used as a form of identity access management and access control. It is also used to identify individuals in groups that are under surveillance. The book consists of 13 chapters, each focusing on a certain aspect of the problem. The book chapters are divided into three sections: physical biometrics, behavioral biometrics and medical biometrics. The key objective of the book is to provide comprehensive reference and text on human authentication and people identity verification from both physiological, behavioural and other points of view. It aims to publish new insights into current innovations in computer systems and technology for biometrics development and its applications. The book was reviewed by the editor Dr. Jucheng Yang, and many of the guest editors, such as Dr. Girija Chetty, Dr. Norman Poh, Dr. Loris Nanni, Dr. Jianjiang Feng, Dr. Dongsun Park, Dr. Sook Yoon and so on, who also made a significant contribution to the book
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