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1.
Djamel Bouchaffra Author Vitae 《Pattern recognition》2010,43(7):2590-2607
Current extensions of hidden Markov models such as structural, hierarchical, coupled, and others have the power to classify complex and highly organized patterns. However, one of their major limitations is the inability to cope with topology: When applied to a visible observation (VO) sequence, the traditional HMM-based techniques have difficulty predicting the n-dimensional shape formed by the symbols of the VO sequence. To fulfill this need, we propose a novel paradigm named “topological hidden Markov models” (THMMs) that classifies VO sequences by embedding the nodes of an HMM state transition graph in a Euclidean space. This is achieved by modeling the noise embedded in the shape generated by the VO sequence. We cover the first and second level topological HMMs. We describe five basic problems that are assigned to a second level topological hidden Markov model: (1) sequence probability evaluation, (2) statistical decoding, (3) structural decoding, (4) topological decoding, and (5) learning. To show the significance of this research, we have applied the concept of THMMs to: (i) predict the ASCII class assigned to a handwritten numeral, and (ii) map protein primary structures to their 3D folds. The results show that the second level THMMs outperform the SHMMs and the multi-class SVM classifiers significantly. 相似文献
2.
Mohamed Sadok Cherif Habib Chabchoub Belaïd Aouni 《International Transactions in Operational Research》2010,17(1):85-102
Quality function deployment (QFD) is a customer-oriented design tool for developing new or improved products to achieve higher customer satisfaction by integrating various functions of an organization. The engineering characteristics (ECs) affecting the product performances are designed to match the customer attributes (CAs). However, from the viewpoint of the QFD team, product design processes are performed in imprecise environments, and more than one factor must be taken into account in determining the target levels of ECs, especially the limited resources and increased market competition. This paper presents an imprecise goal programming (GP) approach to determine the optimum target levels of ECs in QFD for maximizing customer satisfaction under resource limitation and considerations of market competition. Based on benchmarking data of CAs, the concept of satisfaction functions is utilized to formulate explicitly the customer's preferences and to integrate the competitive analysis of target market into the modelling and solution process. In addition, the relationships linking CAs and ECs and the ECs to each other are integrated by functional relationships. The proposed approach will be illustrated through a car door design example. 相似文献
3.
Rafael Antonello Stênio Fernandes Josilene Moreira Paulo Cunha Carlos Kamienski Djamel Sadok 《Multimedia Systems》2009,15(1):33-47
Virtual Worlds (VW), such as Massive Multiplayer Online Social Games, have been gaining increasing attention in the last few
years, mainly due to the new way users interact with them. However, little effort has been devoted to understand their traffic
profile and the implications to the traffic management area. With the current growing rate of VWs’ usage, their traffic demand
could eventually impose a significant burden on the operation of a typical Internet Service Provider (ISP) network. In this
paper, we seek to understand the traffic behavior of an increasingly popular VW application, namely Second Life (SL), from
both the connection and network level perspectives. We also show results of a traffic analysis of a SL client, when an avatar
performs different actions in the VW, at different places and under different network conditions. Our results show that SL
makes intensive use of network resources (mostly bandwidth), since the capacity needed for having a full SL experience (listening
to live music) may reach 500 kbps. We then extend the traffic analysis work on SL by providing analytical models for its traffic
profile. We aim at helping the network management and planning area to estimate the impact of an intense use of such VW on
access links or core networks. Such synthetic models are also useful to the networking research community for the use in network
simulations. 相似文献
4.
Sadok Rezig Zied Achour Mohamed-Ali Kammoun 《International journal of systems science》2016,47(14):3425-3435
This paper addresses the synthesis of Petri net (PN) controller for the forbidden state transition problem with a new utilisation of the theory of regions. Moreover, as any method of control synthesis based on a reachability graph, the theory of regions suffers from the combinatorial explosion problem. The proposed work minimises the number of equations in the linear system of theory of regions and therefore one can reduce the computation time. In this paper, two different approaches are proposed to select minimal cuts in the reachability graph in order to synthesise a PN controller. Thanks to a switch from one cut to another, one can activate and deactivate the corresponding?PNcontroller. An application is implemented in a flexible manufacturing system to illustrate the present method. Finally, comparison with previous works with experimental results in obtaining a maximally permissive controller is presented. 相似文献
5.
Ahmed Samet Eric Lefèvre Sadok Ben Yahia 《Journal of Intelligent Information Systems》2016,47(1):135-163
Associative classification has been shown to provide interesting results whenever of use to classify data. With the increasing complexity of new databases, retrieving valuable information and classifying incoming data is becoming a thriving and compelling issue. The evidential database is a new type of database that represents imprecision and uncertainty. In this respect, extracting pertinent information such as frequent patterns and association rules is of paramount importance task. In this work, we tackle the problem of pertinent information extraction from an evidential database. A new data mining approach, denoted EDMA, is introduced that extracts frequent patterns overcoming the limits of pioneering works of the literature. A new classifier based on evidential association rules is thus introduced. The obtained association rules, as well as their respective confidence values, are studied and weighted with respect to their relevance. The proposed methods are thoroughly experimented on several synthetic evidential databases and showed performance improvement. 相似文献
6.
Ligand‐Free Synthesis of Aluminum‐Doped Zinc Oxide Nanocrystals and their Use as Optical Spacers in Color‐Tuned Highly Efficient Organic Solar Cells 下载免费PDF全文
Meriem Gaceur Sadok Ben Dkhil David Duché Fatima Bencheikh Jean‐Jacques Simon Ludovic Escoubas Mahdi Mansour Antonio Guerrero Germà Garcia‐Belmonte Xianjie Liu Mats Fahlman Walid Dachraoui Abdou Karim Diallo Christine Videlot‐Ackermann Olivier Margeat Jörg Ackermann 《Advanced functional materials》2016,26(2):243-253
The color of polymer solar cells using an opaque electrode is given by the reflected light, which depends on the composition and thickness of each layer of the device. Metal‐oxide‐based optical spacers are intensively studied in polymer solar cells aiming to optimize the light absorption. However, the low conductivity of materials such as ZnO and TiO2 limits the thickness of such optical spacers to tenths of nanometers. A novel synthesis route of cluster‐free Al‐doped ZnO (AZO) nanocrystals (NCs) is presented for solution processing of highly conductive layers without the need of temperature annealing, including thick optical spacers on top of polymer blends. The processing of 80 nm thick optical spacers based on AZO nanocrystal solutions on top of 200 nm thick polymer blend layer is demonstrated leading to improved photocurrent density of 17% compared to solar cells using standard active layers of 90 nm in combination with thin ZnO‐based optical spacers. These AZO NCs also open new opportunities for the processing of high‐efficiency color tuned solar cells. For the first time, it is shown that applying solution‐processed thick optical spacer with polymer blends of different thicknesses can process solar cells of similar efficiency over 7% but of different colors. 相似文献
7.
Mohammed Aider Djamel Djenane Wassef B. Ounis 《International Journal of Food Science & Technology》2012,47(5):1028-1036
Amino acid composition, protein hydrophobicity, foaming and emulsifying properties of mustard protein isolate at pH 3, 5, 7 and in 0.05 and 0.1 m NaCl were studied. Glutamic (19.18 ± 0.30%) and aspartic (7.49 ± 0.11%) acids were the dominants. Foaming ability was enhanced by NaCl. Time to reach 75 mL foam was 23% higher in water than in NaCl. Drained volume after 10 min was concentration dependent and was the lowest in 0.05 and 0.1 m NaCl at protein concentration of 2.5% and 5%. The emulsifying properties were pH and concentration dependent, and the best results were obtained at pH 3, corresponding to the highest positive charge density of the protein surface. The highest emulsion stability (90.22 ± 3.52%) was obtained in 0.05 m NaCl and 5% protein concentration, whereas the lowest (63.00 ± 1.06%) was in water at all protein concentrations. Protein hydrophobicity was low and depended of pH but not of NaCl. 相似文献
8.
Kelvin L. Dias Djamel F. H. Sadok Stênio F. L. Fernandes Judith Kelner 《Wireless Networks》2010,16(1):39-56
This paper presents two novel frameworks for session admission control and resource reservation in the context of next generation mobile and cellular networks. We also devised a special scheme that avoids per-user reservation signaling overhead in order to meet scalability requirements needed for next generation multi-access networks. The first proposal, Distributed Call Admission Control with Aggregate Resource Reservation (VR), uses mobility prediction based on mobile positioning system location information and takes into account the expected bandwidth to be used by calls handing off to and from neighboring cells within a configurable estimation time window. In conjunction, a novel concept called virtual reservation has been devised to prevent per-user reservation. Our second proposal, Local Call Admission Control and Time Series-based Resource Reservation, takes into account the expected bandwidth to be used by calls handed off from neighboring cells based only on local information stored into the current cell a user is seeking admission to. To this end, we suggest the use of two time series-based models for predicting handoff load: the Trigg and Leach (TL), which is an adaptive exponential smoothing technique, and Autoregressive Integrated Moving Average (ARIMA) that uses the Box and Jenkins methodology. It is worth to emphasize that the use of bandwidth prediction based on ARIMA technique still exist for wireless networks. The novelty of our approach is to build an adaptive framework based on ARIMA technique that takes into account the measured handoff dropping probability in order to tuning the prediction time window size so increasing the prediction accuracy. The proposed schemes are compared through simulations with the fixed guard channel (GC) and other optimized dynamic reservation-based proposals present in the literature. The results show that our schemes outperform many others and that the simpler local proposal based on TL can grant nearly similar levels of handoff dropping probability as compared to those from more the complex distributed approach. 相似文献
9.
10.
Chamekh Ould M'bareck Michel Metayer Dominique Langevin Sadok Roudesli 《应用聚合物科学杂志》1996,62(1):161-165
The miscibility of poly(vinyl alcohol) (PVA) and poly(styrenesulfonic acid) (PSSA) in dilute aqueous solutions was studied by a viscosimetric method. At a constant molecular weight of PSSA, it was found that the miscibility of both polymers increases with the molecular weight and the number of acetate groups of the PVA samples (1 and 12% unhydrolyzed sites). Moreover, this miscibility increases slightly with the total mixture concentration in the interval 1–2 g/dL. By comparison of the results of reduced viscosity of PVA/PSSA and PVA/poly(sodium styrenesulfonate) (PSSNa) mixtures, it has been deduced that the miscibility of two polymers is due mainly to intermolecular interactions between the hydroxyl and sulfonic groups of PVA and PSSA, respectively. These groups act as acceptors and donors of hydrogen bonds which are the responsible for polymers' miscibility. © 1996 John Wiley & Sons, Inc. 相似文献