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81.
Muneeb?Dawood Raouf?HamzaouiEmail author Shakeel?Ahmad Marwan?Al-Akaidi 《Signal, Image and Video Processing》2016,10(6):1119-1126
Providing high-quality video for packet-switched wireless video telephony on handheld devices is a challenging task due to packet loss, varying bandwidth, and end-to-end delay constraints. While many error resilience techniques have been proposed for video transmission over wireless channels, only a few were specifically designed for mobile video telephony. We propose a low-complexity channel-adaptive error resilience technique for packet-switched mobile video telephony, which combines rateless coding, feedback, and reference picture selection. In contrast to previous approaches, our technique uses cumulative feedback at every transmission opportunity and predicts when decoding is likely to fail so that reference picture selection can be triggered at an early stage. Experimental results for H.264 video sequences show that the proposed technique can achieve improvements of 1.64 dB in peak signal-to-noise ratio over benchmark techniques in simulated Long-Term Evolution networks. 相似文献
82.
Sharif Aljoaba Oscar Dillon Jr. Marwan Khraisheh I. S. Jawahir 《Journal of Materials Engineering and Performance》2012,21(7):1141-1150
The ability to generate nano-sized grains is one of the advantages of friction stir processing (FSP). However, the high temperatures generated during the stirring process within the processing zone stimulate the grains to grow after recrystallization. Therefore, maintaining the small grains becomes a critical issue when using FSP. In the present reports, coolants are applied to the fixture and/or processed material in order to reduce the temperature and hence, grain growth. Most of the reported data in the literature concerning cooling techniques are experimental. We have seen no reports that attempt to predict these quantities when using coolants while the material is undergoing FSP. Therefore, there is need to develop a model that predicts the resulting grain size when using coolants, which is an important step toward designing the material microstructure. In this study, two three-dimensional computational fluid dynamics (CFD) models are reported which simulate FSP with and without coolant application while using the STAR CCM+ CFD commercial software. In the model with the coolant application, the fixture (backing plate) is modeled while is not in the other model. User-defined subroutines were incorporated in the software and implemented to investigate the effects of changing process parameters on temperature, strain rate and material velocity fields in, and around, the processed nugget. In addition, a correlation between these parameters and the Zener-Holloman parameter used in material science was developed to predict the grain size distribution. Different stirring conditions were incorporated in this study to investigate their effects on material flow and microstructural modification. A comparison of the results obtained by using each of the models on the processed microstructure is also presented for the case of Mg AZ31B-O alloy. The predicted results are also compared with the available experimental data and generally show good agreement. 相似文献
83.
Nabil M. Al-Areeq Marwan A. Al-Badani Adel H. Salman Mohammed A. Albaroot 《Egyptian Journal of Petroleum》2018,27(4)
The Upper Jurassic samples of Jabal Ayban field, Sabatayn Basin, western Yemen were used to determine the source rock characteristics and petroleum generative potentials. Based on organic geochemical analysis, the Upper Jurassic source rocks have variable TOC content in the range of 0.82–13?wt%, indicating a fair to very good source rock generative potential. The bulk geochemical results showed that Safer Member contains Type III kerogen grading to mixed Type II–III, while the Lam and Meem members displaying generally Type II, mixed Type II–III and Type III kerogens, which have the ability to generate mixed oil and gas accumulations under thermal maturation level. Vitrinite reflectance in the range (0.35–0.78% Ro) and Tmax in the range (411–445?°C), generally proving that the Meem source rocks have sufficient thermal maturity for hydrocarbon-generation, whereas the Lam and Safer are immature source rocks. 1D basin modelling was performed to analyse the hydrocarbon generation and expulsion history of the study area. Calibration of the model with measured VR (% Ro) and (BHT) data shows that the paleo-heat-flow was high at Late Jurassic. The burial/thermal history models indicate that the source rocks in the Lam and Safer members are immature source rocks and the peak oil generation has not been reached yet. The models also indicate that the early hydrocarbon generation (0.64% Ro) in the Meem source rock occurred during late Jurassic at 150?Ma and the main hydrocarbon generation (0.79% Ro) has been reached approximately at 146?Ma. Therefore, the Meem Member can be consider as generative potentials of prospective source rock horizons in Jabal Ayban field, Sabatayn Basin. 相似文献
84.
Mohammad J. Abdel‐Rahman Marwan Krunz Richard Erwin 《International Journal of Satellite Communications and Networking》2015,33(3):197-216
Satellite transmissions are prone to both unintentional and intentional RF interference. Such interference has significant impact on the reliability of packet transmissions. In this paper, we make preliminary steps at exploiting the sensing capabilities of cognitive radios for reliable satellite communications. We propose the use of dynamically adjusted frequency hopping (FH) sequences for satellite transmissions. Such sequences are more robust against targeted interference than fixed FH sequences. In our design, the FH sequence is adjusted according to the outcome of out‐of‐band proactive sensing, carried out by a cognitive radio module that resides in the receiver of the satellite link. Our design, called out‐of‐band sensing‐based dynamic FH, is first analyzed using a discrete‐time Markov chain (DTMC) framework. The transition probabilities of the DTMC are then used to measure the ‘channel stability’, a metric that reflects the freshness of sensed channel interference. Next, out‐of‐band sensing‐based dynamic FH is analyzed following a continuous‐time Markov chain model, and a numerical procedure for determining the ‘optimal’ total sensing time that minimizes the probability of ‘black holes’ is provided. DTMC is appropriate for systems with continuously adjustable power levels; otherwise, continuous‐time Markov chain is the suitable model. We use simulations to study the effects of different system parameters on the performance of our proposed design. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
85.
NA Habib BD Higgs I Marwan R el-Masry A Helmi R Saifi A Abbas F Abdel-Wohab A Abaza H Koensa 《Canadian Metallurgical Quarterly》1993,78(2):121-123
Liver transplantation is an effective therapy for end stage liver disease. Nevertheless in many areas of the world organ availability remains a major problem. We report here the success of the first living-related liver transplantation in Africa. The left lateral lobe of the mother was transplanted orthotopically to her 6 year old child suffering from liver cirrhosis complicating glycogen storage disease. The social and medical problems encountered are discussed. Living-related liver transplantation is a viable option in countries where cadaveric organ donation is either illegal or socially unacceptable. 相似文献
86.
Summary. We consider agreement and leader election on asynchronous complete networks when the processors are reliable, but some of
the channels are subject to failure. Fischer, Lynch, and Paterson have already shown that no deterministic algorithm can solve
the agreement problem on asynchronous networks if any processor fails during the execution of the algorithm. Therefore, we
consider only channel failures. The type of channel failure we consider in this paper is Byzantine failure, that is, channels fail by altering messages, sending false information, forging messages, losing messages at will,
and so on. There are no restrictions on the behavior of a faulty channel. Therefore, a faulty channel may act as an adversary
who forges messages on purpose to prevent the successful completion of the algorithm. Because we assume an asynchronous network,
the channel delays are arbitrary. Thus, the faulty channels may not be detectable unless, for example, the faulty channels
cause garbage to be sent. We present the first known agreement and leader election algorithm for asynchronous complete networks
in which the processors are reliable but some channels may be Byzantine faulty. The algorithm can tolerate up to [n−22] faulty channels, where n is the number of processors in the network. We show that the bound on the number of faulty channels is optimal. When the
processors terminate their corresponding algorithms, all the processors in the network will have the same correct vector,
where the vector contains the private values of all the processors.
Received: May 1994/Accepted: July 1995 相似文献
87.
Sundas Rukhsar Mazhar Javed Awan Usman Naseem Dilovan Asaad Zebari Mazin Abed Mohammed Marwan Ali Albahar Mohammed Thanoon Amena Mahmoud 《计算机系统科学与工程》2023,47(1):791-807
Web-blogging sites such as Twitter and Facebook are heavily influenced by emotions, sentiments, and data in the modern era. Twitter, a widely used microblogging site where individuals share their thoughts in the form of tweets, has become a major source for sentiment analysis. In recent years, there has been a significant increase in demand for sentiment analysis to identify and classify opinions or expressions in text or tweets. Opinions or expressions of people about a particular topic, situation, person, or product can be identified from sentences and divided into three categories: positive for good, negative for bad, and neutral for mixed or confusing opinions. The process of analyzing changes in sentiment and the combination of these categories is known as “sentiment analysis.” In this study, sentiment analysis was performed on a dataset of 90,000 tweets using both deep learning and machine learning methods. The deep learning-based model long-short-term memory (LSTM) performed better than machine learning approaches. Long short-term memory achieved 87% accuracy, and the support vector machine (SVM) classifier achieved slightly worse results than LSTM at 86%. The study also tested binary classes of positive and negative, where LSTM and SVM both achieved 90% accuracy. 相似文献
88.
An automated decision-support system for non-proliferative diabetic retinopathy disease based on MAs and HAs detection 总被引:1,自引:0,他引:1
Diabetic retinopathy (DR) has become a serious threat in our society, which causes 45% of the legal blindness in diabetes patients. Early detection as well as the periodic screening of DR helps in reducing the progress of this disease and in preventing the subsequent loss of visual capability. This paper provides an automated diagnosis system for DR integrated with a user-friendly interface. The grading of the severity level of DR is based on detecting and analyzing the early clinical signs associated with the disease, such as microaneurysms (MAs) and hemorrhages (HAs). The system extracts some retinal features, such as optic disc, fovea, and retinal tissue for easier segmentation of dark spot lesions in the fundus images. That is followed by the classification of the correctly segmented spots into MAs and HAs. Based on the number and location of MAs and HAs, the system quantifies the severity level of DR. A database of 98 color images is used in order to evaluate the performance of the developed system. From the experimental results, it is found that the proposed system achieves 84.31% and 87.53% values in terms of sensitivity for the detection of MAs and HAs respectively. In terms of specificity, the system achieves 93.63% and 95.08% values for the detection of MAs and HAs respectively. Also, the proposed system achieves 68.98% and 74.91% values in terms of kappa coefficient for the detection of MAs and HAs respectively. Moreover, the system yields sensitivity and specificity values of 89.47% and 95.65% for the classification of DR versus normal. 相似文献
89.
Petri nets are directed, weighted bipartite graphs that have successfully been applied to the systems biology of metabolic
and signal transduction pathways in modeling both stochastic (discrete) and deterministic (continuous) processes. Here we
exemplify how molecular mechanisms, biochemical or genetic, can be consistently respresented in the form of place/transition
Petri nets. We then describe the application of Petri nets to the reconstruction of molecular and genetic networks from experimental
data and their power to represent biological processes with arbitrary degree of resolution of the subprocesses at the cellular
and the molecular level. Petri nets are executable formal language models that permit the unambiguous visualization of regulatory
mechanisms, and they can be used to encode the results of mathematical algorithms for the reconstruction of causal interaction
networks from experimental time series data. 相似文献
90.
Marwan A. Gharaybeh Michael L. Bushnell Vishwani D. Agrawal 《Journal of Electronic Testing》1997,11(1):55-67
We classify all path-delay faults of a combinational circuit intothree categories: singly-testable (ST), multiply-testable (MT), and singly-testable dependent} (ST-dependent). The classification uses anyunaltered single stuck-at fault test generation tool. Only two runsof this tool on a model network derived from the original network areperformed. As a by-product of this process, we generate single andmultiple input change delay tests for all testable faults. With thesetests, we expect that most defective circuits are identified. All STfaults are guaranteed detection in the case of a single fault, andsome may be guaranteed detection through robust and validatablenon-robust tests even in the case of multiple faults. An ST-dependentfault can affect the circuit speed only if certain ST faults arepresent. Thus, if all ST faults are tested, the ST-dependent faultsneed not be tested. MT faults cannot be guaranteed detection, butaffect the speed only if delay faults simultaneously exist on a setof paths, none of which is ST. Examples and results on several ISCAS89 benchmarks are presented. The method of classification throughtest generation using a model network is complex and can be appliedto circuits of moderate size. For larger circuits, alternativemethods will have to be explored in the future. 相似文献