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61.
Motion study of the hip joint in extreme postures 总被引:2,自引:0,他引:2
Caecilia Charbonnier Lazhari Assassi Pascal Volino Nadia Magnenat-Thalmann 《The Visual computer》2009,25(9):873-882
Many causes can be at the origin of hip osteoarthritis (e.g., cam/pincer impingements), but the exact pathogenesis for idiopathic
osteoarthritis has not yet been clearly delineated. The aim of the present work is to analyze the consequences of repetitive
extreme hip motion on the labrum cartilage. Our hypothesis is that extreme movements can induce excessive labral deformations
and lead to early arthritis. To verify this hypothesis, an optical motion capture system is used to estimate the kinematics
of patient-specific hip joint, while soft tissue artifacts are reduced with an effective correction method. Subsequently,
a physical simulation system is used during motion to compute accurate labral deformations and to assess the global pressure
of the labrum, as well as any local pressure excess that may be physiologically damageable. Results show that peak contact
pressures occur at extreme hip flexion/abduction and that the pressure distribution corresponds with radiologically observed
damage zones in the labrum.
相似文献
Nadia Magnenat-ThalmannEmail: |
62.
Rule-based intrusion detection systems generally rely on hand crafted signatures developed by domain experts. This could lead to a delay in updating the signature bases and potentially compromising the security of protected systems. In this paper, we present a biologically-inspired computational approach to dynamically and adaptively learn signatures for network intrusion detection using a supervised learning classifier system. The classifier is an online and incremental parallel production rule-based system.A signature extraction system is developed that adaptively extracts signatures to the knowledge base as they are discovered by the classifier. The signature extraction algorithm is augmented by introducing new generalisation operators that minimise overlap and conflict between signatures. Mechanisms are provided to adapt main algorithm parameters to deal with online noisy and imbalanced class data. Our approach is hybrid in that signatures for both intrusive and normal behaviours are learnt.The performance of the developed systems is evaluated with a publicly available intrusion detection dataset and results are presented that show the effectiveness of the proposed system. 相似文献
63.
T. Hussein M.S. Saad A.L. Elshafei A. Bahgat 《Expert systems with applications》2009,36(10):12104-12112
This paper introduces a robust adaptive fuzzy controller as a power system stabilizer (RFPSS) used to damp inter-area modes of oscillation following disturbances in power systems. In contrast to the IEEE standard multi-band power system stabilizer (MB-PSS), robust adaptive fuzzy-based stabilizers are more efficient because they cope with oscillations at different operating points. The proposed controller adopts a dynamic inversion approach. Since feedback linearization is practically imperfect, components that ensure robust and adaptive performance are included in the control law to compensate for modelling errors and achieve acceptable tracking errors. Two fuzzy systems are implemented. The first system models the nominal values of the system’s nonlinearities. The second system is an adaptive one that compensates for modelling errors. A feedback linearization-based control law is implemented using the identified model. The gains of the controller are tuned via a particle swarm optimization routine to ensure system stability and minimum sum of the squares of the speed deviations. A bench-mark problem of a 4-machine 2-area power system is used to demonstrate the performance of the proposed controller and to show its superiority over other conventional stabilizers used in the literature. 相似文献
64.
J��r?me Schmid Jos�� A. Iglesias?Guiti��n Enrico Gobbetti Nadia Magnenat-Thalmann 《The Visual computer》2011,27(2):85-95
Despite the ability of current GPU processors to treat heavy parallel computation tasks, its use for solving medical image
segmentation problems is still not fully exploited and remains challenging. A lot of difficulties may arise related to, for
example, the different image modalities, noise and artifacts of source images, or the shape and appearance variability of
the structures to segment. Motivated by practical problems of image segmentation in the medical field, we present in this
paper a GPU framework based on explicit discrete deformable models, implemented over the NVidia CUDA architecture, aimed for
the segmentation of volumetric images. The framework supports the segmentation in parallel of different volumetric structures
as well as interaction during the segmentation process and real-time visualization of the intermediate results. Promising
results in terms of accuracy and speed on a real segmentation experiment have demonstrated the usability of the system. 相似文献
65.
Hussein Abdel-Jaber Mike Woodward Fadi Thabtah Amer Abu-Ali 《Journal of Network and Computer Applications》2008,31(4):750-770
Due to the rapid development in computer networks, congestion becomes a critical issue. Congestion usually occurs when the connection demands on network resources, i.e. buffer spaces, exceed the available ones. We propose in this paper a new discrete-time queueing network analytical model based on dynamic random early drop (DRED) algorithm to control the congestion in early stages. We apply our analytical model on two-queue nodes queueing network. Furthermore, we compare between the proposed analytical model and three known active queue management (AQM) algorithms, including DRED, random early detection (RED) and adaptive RED, in order to figure out which of them offers better quality of service (QoS). We also experimentally compare the queue nodes of the proposed analytical model and the three AQM methods in terms of different performance measures, including, average queue length, average queueing delay, throughput, packet loss probability, etc., aiming to determine the queue node that offers better performance. 相似文献
66.
Abdullah AH Abdullah EA Zainal Z Hussein MZ Ban TK 《Water science and technology》2012,65(9):1632-1638
The adsorption of methyl orange dye from aqueous solution onto penta-bismuth hepta-oxide nitrate, Bi(5)O(7)NO(3), synthesized by precipitation method, was studied in a batch adsorption system. The effects of operation parameters such as adsorbent dose, initial dye concentration, pH and temperature were investigated. The adsorption equilibrium and mechanism of adsorption was evaluated by Langmuir and Freundlich isotherm and different kinetic models, respectively. The results indicate that adsorption is highly dependent on all operation parameters. At optimum conditions, the adsorption capacity was found to be 18.9 mg/g. The adsorption data fits well with the Langmuir isotherm model indicating monolayer coverage of adsorbate molecules on the surface of Bi(5)O(7)NO(3). The kinetic studies show that the adsorption process is a second-order kinetic reaction. Although intra-particle diffusion limits the rate of adsorption, the multi-linearity plot of intra-particle model shows the importance of both film and intra-particle diffusion as the rate-limiting steps of the dye removal. Thermodynamic parameters show that the adsorption process is endothermic, spontaneous and favourable at high temperature. 相似文献
67.
Hussein Muzahim Aziz Markus Fiedler H?kan Grahn Lars Lundberg 《Multimedia Systems》2012,18(3):251-262
Streaming video over a wireless network faces several challenges such as high packet error rates, bandwidth variations, and delays, which could have negative effects on the video streaming and the viewer will perceive a frozen picture for certain durations due to loss of frames. In this study, we propose a Time Interleaving Robust Streaming (TIRS) technique to significantly reduce the frozen video problem and provide a satisfactory quality for the mobile viewer. This is done by reordering the streaming video frames as groups of even and odd frames. The objective of streaming the video in this way is to avoid the losses of a sequence of neighbouring frames in case of a long sequence interruption. We evaluate our approach by using a user panel and mean opinion score (MOS) measurements; where the users observe three levels of frame losses. The results show that our technique significantly improves the smoothness of the video on the mobile device in the presence of frame losses, while the transmitted data are only increased by almost 9% (due to reduced time locality). 相似文献
68.
Compact yet efficient hardware implementation of artificial neural networks with customized topology
Nadia Nedjah Rodrigo Martins da Silva Luiza de Macedo Mourelle 《Expert systems with applications》2012,39(10):9191-9206
There are several neural network implementations using either software, hardware-based or a hardware/software co-design. This work proposes a hardware architecture to implement an artificial neural network (ANN), whose topology is the multilayer perceptron (MLP). In this paper, we explore the parallelism of neural networks and allow on-the-fly changes of the number of inputs, number of layers and number of neurons per layer of the net. This reconfigurability characteristic permits that any application of ANNs may be implemented using the proposed hardware. In order to reduce the processing time that is spent in arithmetic computation, a real number is represented using a fraction of integers. In this way, the arithmetic is limited to integer operations, performed by fast combinational circuits. A simple state machine is required to control sums and products of fractions. Sigmoid is used as the activation function in the proposed implementation. It is approximated by polynomials, whose underlying computation requires only sums and products. A theorem is introduced and proven so as to cover the arithmetic strategy of the computation of the activation function. Thus, the arithmetic circuitry used to implement the neuron weighted sum is reused for computing the sigmoid. This resource sharing decreased drastically the total area of the system. After modeling and simulation for functionality validation, the proposed architecture synthesized using reconfigurable hardware. The results are promising. 相似文献
69.
Nadia Nedjah Marcus Vinícius Carvalho da Silva Luiza de Macedo Mourelle 《Expert systems with applications》2012,39(3):2771-2782
Network-on-chip (NoC) are considered the next generation of communication infrastructure in embedded systems. In the platform-based design methodology, an application is implemented by a set of collaborative intellectual property (IP) blocks. The selection of the most suited set of IPs as well as their physical mapping onto the NoC infrastructure to implement efficiently the application at hand are two hard combinatorial problems that occur during the synthesis process of Noc-based embedded system implementation. In this paper, we propose an innovative preference-based multi-objective evolutionary methodology to perform the assignment and mapping stages. We use one of the well-known and efficient multi-objective evolutionary algorithms NSGA-II and microGA as a kernel. The optimization processes of assignment and mapping are both driven by the minimization of the required silicon area and imposed execution time of the application, considering that the decision maker’s preference is a pre-specified value of the overall power consumption of the implementation. 相似文献
70.
We develop a generalized Extended Linear Hazard Regression (ELHR) model with linear time-varying coefficients to estimate reliability under normal operating conditions using failure time data obtained from accelerated conditions. The model considers the effect of proportional hazards, time-varying coefficients and also time-scale changes. Extensive simulation experiments demonstrate that the ELHR model provides more accurate reliability estimates than those obtained using existing accelerated life testing models. We utilize the ELHR model to study the time-dependent dielectric breakdown of thermal oxides on n-type 6H-SiC using laboratory data. The results show that oxide reliability considerations effectively preclude SiC MOS devices from many high-temperature applications. 相似文献