The Experts below are selected from a list of 8679 Experts worldwide ranked by ideXlab platform
Andrew T Weakley - One of the best experts on this subject based on the ideXlab platform.
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evidential significance of automotive paint trace evidence using a pattern recognition based infrared library Search engine for the paint data query forensic database
2016Co-Authors: Barry K Lavine, Matthew D. Allen, Collin White, Ayuba Fasasi, Andrew T WeakleyAbstract:A prototype library Search engine has been further developed to Search the infrared spectral libraries of the paint data query database to identify the line and model of a vehicle from the clear coat, surfacer-primer, and e-coat layers of an intact paint chip. For this study, Search prefilters were developed from 1181 automotive paint systems spanning 3 manufacturers: General Motors, Chrysler, and Ford. The best match between each unknown and the spectra in the hit list generated by the Search prefilters was identified using a cross-correlation library Search algorithm that performed both a forward and Backward Search. In the forward Search, spectra were divided into intervals and further subdivided into windows (which corresponds to the time lag for the comparison) within those intervals. The top five hits identified in each Search window were compiled; a histogram was computed that summarized the frequency of occurrence for each library sample, with the IR spectra most similar to the unknown flagged. The Backward Search computed the frequency and occurrence of each line and model without regard to the identity of the individual spectra. Only those lines and models with a frequency of occurrence greater than or equal to 20% were included in the final hit list. If there was agreement between the forward and Backward Search results, the specific line and model common to both hit lists was always the correct assignment. Samples assigned to the same line and model by both Searches are always well represented in the library and correlate well on an individual basis to specific library samples. For these samples, one can have confidence in the accuracy of the match. This was not the case for the results obtained using commercial library Search algorithms, as the hit quality index scores for the top twenty hits were always greater than 99%.
Barry K Lavine - One of the best experts on this subject based on the ideXlab platform.
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Pattern recognition-assisted infrared library Searching of the paint data query database to enhance lead information from automotive paint trace evidence
2017Co-Authors: Barry K Lavine, Collin G. White, Matthew D. Allen, Andrew WeakleyAbstract:Multilayered automotive paint fragments, which are one of the most complex materials encountered in the forensic science laboratory, provide crucial links in criminal investigations and prosecutions. To determine the origin of these paint fragments, forensic automotive paint examiners have turned to the paint data query (PDQ) database, which allows the forensic examiner to compare the layer sequence and color, texture, and composition of the sample to paint systems of the original equipment manufacturer (OEM). However, modern automotive paints have a thin color coat and this layer on a microscopic fragment is often too thin to obtain accurate chemical and topcoat color information. A Search engine has been developed for the infrared (IR) spectral libraries of the PDQ database in an effort to improve discrimination capability and permit quantification of discrimination power for OEM automotive paint comparisons. The similarity of IR spectra of the corresponding layers of various records for original finishes in the PDQ database often results in poor discrimination using commercial library Search algorithms. A pattern recognition approach employing pre-filters and a cross-correlation library Search algorithm that performs both a forward and Backward Search has been used to significantly improve the discrimination of IR spectra in the PDQ database and thus improve the accuracy of the Search. This improvement permits inter-comparison of OEM automotive paint layer systems using the IR spectra alone. Such information can serve to quantify the discrimination power of the original automotive paint encountered in casework and further efforts to succinctly communicate trace evidence to the courts.
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evidential significance of automotive paint trace evidence using a pattern recognition based infrared library Search engine for the paint data query forensic database
2016Co-Authors: Barry K Lavine, Matthew D. Allen, Collin White, Ayuba Fasasi, Andrew T WeakleyAbstract:A prototype library Search engine has been further developed to Search the infrared spectral libraries of the paint data query database to identify the line and model of a vehicle from the clear coat, surfacer-primer, and e-coat layers of an intact paint chip. For this study, Search prefilters were developed from 1181 automotive paint systems spanning 3 manufacturers: General Motors, Chrysler, and Ford. The best match between each unknown and the spectra in the hit list generated by the Search prefilters was identified using a cross-correlation library Search algorithm that performed both a forward and Backward Search. In the forward Search, spectra were divided into intervals and further subdivided into windows (which corresponds to the time lag for the comparison) within those intervals. The top five hits identified in each Search window were compiled; a histogram was computed that summarized the frequency of occurrence for each library sample, with the IR spectra most similar to the unknown flagged. The Backward Search computed the frequency and occurrence of each line and model without regard to the identity of the individual spectra. Only those lines and models with a frequency of occurrence greater than or equal to 20% were included in the final hit list. If there was agreement between the forward and Backward Search results, the specific line and model common to both hit lists was always the correct assignment. Samples assigned to the same line and model by both Searches are always well represented in the library and correlate well on an individual basis to specific library samples. For these samples, one can have confidence in the accuracy of the match. This was not the case for the results obtained using commercial library Search algorithms, as the hit quality index scores for the top twenty hits were always greater than 99%.
Songlin Hu - One of the best experts on this subject based on the ideXlab platform.
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effective pruning algorithm for qos aware service composition
2009Co-Authors: Zhenqiu Huang, Wei Jiang, Songlin HuAbstract:Abstract—Automatic service composition has been a hottopic in both academia and industry. It begins with syntacticcomposition, and then evolves semantic description. Recently, QoS of the composition comes into reSearchers’ mind, which aims at meeting the need of the overall qualities like service fee, response time, throughput, etc. In this paper, a novel QoSaware approach is presented. It adopts a forward filtering algorithm to reduce the number of service candidates, along with a modified dynamic programming approach to compute optimal values. Finally, a Backward Search is utilized to find out the optimal composition results efficiently.
Matthew D. Allen - One of the best experts on this subject based on the ideXlab platform.
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Pattern recognition-assisted infrared library Searching of the paint data query database to enhance lead information from automotive paint trace evidence
2017Co-Authors: Barry K Lavine, Collin G. White, Matthew D. Allen, Andrew WeakleyAbstract:Multilayered automotive paint fragments, which are one of the most complex materials encountered in the forensic science laboratory, provide crucial links in criminal investigations and prosecutions. To determine the origin of these paint fragments, forensic automotive paint examiners have turned to the paint data query (PDQ) database, which allows the forensic examiner to compare the layer sequence and color, texture, and composition of the sample to paint systems of the original equipment manufacturer (OEM). However, modern automotive paints have a thin color coat and this layer on a microscopic fragment is often too thin to obtain accurate chemical and topcoat color information. A Search engine has been developed for the infrared (IR) spectral libraries of the PDQ database in an effort to improve discrimination capability and permit quantification of discrimination power for OEM automotive paint comparisons. The similarity of IR spectra of the corresponding layers of various records for original finishes in the PDQ database often results in poor discrimination using commercial library Search algorithms. A pattern recognition approach employing pre-filters and a cross-correlation library Search algorithm that performs both a forward and Backward Search has been used to significantly improve the discrimination of IR spectra in the PDQ database and thus improve the accuracy of the Search. This improvement permits inter-comparison of OEM automotive paint layer systems using the IR spectra alone. Such information can serve to quantify the discrimination power of the original automotive paint encountered in casework and further efforts to succinctly communicate trace evidence to the courts.
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evidential significance of automotive paint trace evidence using a pattern recognition based infrared library Search engine for the paint data query forensic database
2016Co-Authors: Barry K Lavine, Matthew D. Allen, Collin White, Ayuba Fasasi, Andrew T WeakleyAbstract:A prototype library Search engine has been further developed to Search the infrared spectral libraries of the paint data query database to identify the line and model of a vehicle from the clear coat, surfacer-primer, and e-coat layers of an intact paint chip. For this study, Search prefilters were developed from 1181 automotive paint systems spanning 3 manufacturers: General Motors, Chrysler, and Ford. The best match between each unknown and the spectra in the hit list generated by the Search prefilters was identified using a cross-correlation library Search algorithm that performed both a forward and Backward Search. In the forward Search, spectra were divided into intervals and further subdivided into windows (which corresponds to the time lag for the comparison) within those intervals. The top five hits identified in each Search window were compiled; a histogram was computed that summarized the frequency of occurrence for each library sample, with the IR spectra most similar to the unknown flagged. The Backward Search computed the frequency and occurrence of each line and model without regard to the identity of the individual spectra. Only those lines and models with a frequency of occurrence greater than or equal to 20% were included in the final hit list. If there was agreement between the forward and Backward Search results, the specific line and model common to both hit lists was always the correct assignment. Samples assigned to the same line and model by both Searches are always well represented in the library and correlate well on an individual basis to specific library samples. For these samples, one can have confidence in the accuracy of the match. This was not the case for the results obtained using commercial library Search algorithms, as the hit quality index scores for the top twenty hits were always greater than 99%.
Ahmed Helmy - One of the best experts on this subject based on the ideXlab platform.
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the stress method for boundary point performance analysis of end to end multicast timer suppression mechanisms
2004Co-Authors: Ahmed Helmy, S K Gupta, Deborah EstrinAbstract:The advent of multicast and the growth and complexity of the Internet has complicated network protocol design and evaluation. Evaluation of Internet protocols usually uses random scenarios or scenarios based on designers' intuition. Such an approach may be useful for average case analysis but does not cover boundary-point (worst or best case) scenarios. To synthesize boundary-point scenarios, a more systematic approach is needed. In this paper, we present a method for automatic synthesis of worst and best case scenarios for protocol boundary-point evaluation. Our method uses a fault-oriented test generation (FOTG) algorithm for Searching the protocol and system state space to synthesize these scenarios. The algorithm is based on a global finite state machine (FSM) model. We extend the algorithm with timing semantics to handle end-to-end delays and address performance criteria. We introduce the notion of a virtual LAN to represent delays of the underlying multicast distribution tree. Our algorithms utilize implicit Backward Search using branch and bound techniques and start from given target events. As a case study, we use our method to evaluate variants of the timer suppression mechanism, used in various multicast protocols, with respect to two performance criteria: overhead of response messages and response time. Simulation results for reliable multicast protocols show that our method provides a scalable way for synthesizing worst case scenarios automatically. Results obtained using stress scenarios differ dramatically from those obtained through average case analyses. We hope for our method to serve as a model for applying systematic evaluation to other multicast protocols.
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the stress method for boundary point performance analysis of end to end multicast timer suppression mechanisms
2002Co-Authors: Ahmed Helmy, S K Gupta, Deborah EstrinAbstract:Evaluation of Internet protocols usually uses random scenarios or scenarios based on designers' intuition. Such approach may be useful for average-case analysis but does not cover boundary-point (worst or best-case) scenarios. To synthesize boundary-point scenarios a more systematic approach is needed.In this paper, we present a method for automatic synthesis of worst and best case scenarios for protocol boundary-point evaluation. Our method uses a fault-oriented test generation (FOTG) algorithm for Searching the protocol and system state space to synthesize these scenarios. The algorithm is based on a global finite state machine (FSM) model. We extend the algorithm with timing semantics to handle end-to-end delays and address performance criteria. We introduce the notion of a virtual LAN to represent delays of the underlying multicast distribution tree. The algorithms used in our method utilize implicit Backward Search using branch and bound techniques and start from given target events. This aims to reduce the Search complexity drastically. As a case study, we use our method to evaluate variants of the timer suppression mechanism, used in various multicast protocols, with respect to two performance criteria: overhead of response messages and response time. Simulation results for reliable multicast protocols show that our method provides a scalable way for synthesizing worst-case scenarios automatically. Results obtained using stress scenarios differ dramatically from those obtained through average-case analyses. We hope for our method to serve as a model for applying systematic scenario generation to other multicast protocols.
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systematic testing of multicast routing protocols analysis of forward and Backward Search techniques
2000Co-Authors: Ahmed Helmy, Deborah Estrin, Sandeep K GuptaAbstract:We present a new methodology for developing systematic and automatic test generation algorithms for multipoint protocols. These algorithms attempt to synthesize network topologies and sequences of events that stress the protocol's correctness or performance. This problem can be viewed as a domain-specific Search problem that suffers from the state space explosion problem. One goal of this work is to circumvent the state space explosion problem utilizing knowledge of network and fault modeling, and multipoint protocols. The two approaches investigated are based on forward and Backward Search techniques. We use an extended finite state machine (FSM) model of the protocol. The first algorithm uses forward Search to perform reduced reachability analysis. Using domain-specific information for multicast routing over LAN, the algorithm complexity is reduced from exponential to polynomial in the number of routers. This approach, however, does not fully automate topology synthesis. The second algorithm, the fault-oriented test generation, uses Backward Search for topology synthesis and uses backtracking to generate event sequences instead of Searching forward from initial states. Using these algorithms, we have conducted studies for correctness of the multicast routing protocol PIM.
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systematic testing of multicast routing protocols analysis of forward and Backward Search techniques
2000Co-Authors: Ahmed Helmy, Deborah Estrin, Sandeep K GuptaAbstract:In this paper, we present a new methodology for developing systematic and automatic test generation algorithms for multipoint protocols. These algorithms attempt to synthesize network topologies and sequences of events that stress the protocol's correctness or performance. This problem can be viewed as a domain-specific Search problem that suffers from the state space explosion problem. One goal of this work is to circumvent the state space explosion problem utilizing knowledge of network and fault modeling, and multipoint protocols. The two approaches investigated in this study are based on forward and Backward Search techniques. We use an extended finite state machine (FSM) model of the protocol. The first algorithm uses forward Search to perform reduced reachability analysis. Using domain-specific information for multicast routing over LANs, the algorithm complexity is reduced from exponential to polynomial in the number of routers. This approach, however, does not fully automate topology synthesis. The second algorithm, the fault-oriented test generation, uses Backward Search for topology synthesis and uses backtracking to generate event sequences instead of Searching forward from initial states. Using these algorithms, we have conducted studies for correctness of the multicast routing protocol PIM. We propose to extend these algorithms to study end-to-end multipoint protocols using a virtual LAN that represents delays of the underlying multicast distribution tree.
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fault oriented test generation for multicast routing protocol design
1998Co-Authors: Ahmed Helmy, Deborah Estrin, Sandeep K GuptaAbstract:We present a new algorithm for automatic test generation for multicast routing. Our algorithm processes a finite state machine (FSM) model of the protocol and uses a mix of forward and Backward Search techniques to generate the tests. The output tests include a set of topologies, protocol events and network failures, that lead to violation of protocol correctness and behavioral requirements. We target protocol robustness in specific, and do not attempt to verify other properties in this paper. We apply our method to a multicast routing protocol; PIM-DM, and investigate its behavior in the presence of selective packet loss on LANs and router crashes. Our study unveils several robustness violations in PIM-DM, for which we suggest fixes with the aid of the presented algorithm.
