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Real-time Applications (real-time + application)
Selected AbstractsThe design of supervisory rule-based control in the operating theatre via an anaesthesia simulatorEXPERT SYSTEMS, Issue 1 2002M. Mahfouf The development of online drug administration strategies in operating theatres represents a highly safety-critical situation. The usefulness of different levels of simulation prior to clinical trials has been shown in previous studies in muscle relaxant anaesthesia. Thus, in earlier work on predictive self-tuning control for muscle relaxation a dual computer real-time simulation was undertaken, subsequent to algorithm validation via off-line simulation. In the present approach a supervised rule-based control algorithm is used. The control software was implemented on the actual machine to be used in theatre, while another computer acted as a real-time patient simulator. This set-up has further advantages of providing accurate timing and also finite data accuracy via the ADC/DAC interface, or the equivalent digital lines. Also, it provides for controller design fast simulation studies compared to the real-time application. In this paper, a new architecture which combines several hierarchical levels for control (a Mamdani-type fuzzy controller), adaptation (self-organizing fuzzy logic control) and performance monitoring (fault detection, isolation and accommodation) is developed and applied to a computer real-time simulation platform for muscle relaxant anaesthesia. Experimental results showed that the proposed algorithm fulfilled successfully the requirements for autonomy, i.e. automatic control, adaptation and supervision, and proved effective in dealing with the faults and disturbances which are normally encountered in operating theatres during surgery. [source] Optimizing image matches via a verification modelINTERNATIONAL JOURNAL OF INTELLIGENT SYSTEMS, Issue 11 2010Jimmy Addison Lee In the literature, we have seen a boom in wide-baseline matching approaches proposed for locating correspondences between images. However, wrong correspondences or the so-called outliers are still rather inevitable, especially in urban environments with the presence of repetitive structures, and/or a large dissimilarity in viewpoints. In this paper, we propose a verification model to optimize the image matching results by significantly reducing the number of outliers. Several geometric and appearance-based measurements are exploited, and conditional probability is used to compute the probability of each true correspondence. The model is validated by extensive experiments on images from the ZuBud database, which are taken in different weather conditions, seasons, and with different cameras. It is also demonstrated on a real-time application of an image-based navigation system. © 2010 Wiley Periodicals, Inc. [source] Prospective real-time correction for arbitrary head motion using active markersMAGNETIC RESONANCE IN MEDICINE, Issue 4 2009Melvyn B. Ooi Abstract Patient motion during an MRI exam can result in major degradation of image quality, and is of increasing concern due to the aging population and its associated diseases. This work presents a general strategy for real-time, intraimage compensation of rigid-body motion that is compatible with multiple imaging sequences. Image quality improvements are established for structural brain MRI acquired during volunteer motion. A headband integrated with three active markers is secured to the forehead. Prospective correction is achieved by interleaving a rapid track-and-update module into the imaging sequence. For every repetition of this module, a short tracking pulse-sequence remeasures the marker positions; during head motion, the rigid-body transformation that realigns the markers to their initial positions is fed back to adaptively update the image-plane,maintaining it at a fixed orientation relative to the head,before the next imaging segment of k -space is acquired. In cases of extreme motion, corrupted lines of k -space are rejected and reacquired with the updated geometry. High-precision tracking measurements (0.01 mm) and corrections are accomplished in a temporal resolution (37 ms) suitable for real-time application. The correction package requires minimal additional hardware and is fully integrated into the standard user interface, promoting transferability to clinical practice. Magn Reson Med, 2009. © 2009 Wiley-Liss, Inc. [source] Visyllable Based Speech AnimationCOMPUTER GRAPHICS FORUM, Issue 3 2003Sumedha Kshirsagar Visemes are visual counterpart of phonemes. Traditionally, the speech animation of 3D synthetic faces involvesextraction of visemes from input speech followed by the application of co-articulation rules to generate realisticanimation. In this paper, we take a novel approach for speech animation , using visyllables, the visual counterpartof syllables. The approach results into a concatenative visyllable based speech animation system. The key contributionof this paper lies in two main areas. Firstly, we define a set of visyllable units for spoken English along withthe associated phonological rules for valid syllables. Based on these rules, we have implemented a syllabificationalgorithm that allows segmentation of a given phoneme stream into syllables and subsequently visyllables. Secondly,we have recorded the database of visyllables using a facial motion capture system. The recorded visyllableunits are post-processed semi-automatically to ensure continuity at the vowel boundaries of the visyllables. We defineeach visyllable in terms of the Facial Movement Parameters (FMP). The FMPs are obtained as a result of thestatistical analysis of the facial motion capture data. The FMPs allow a compact representation of the visyllables.Further, the FMPs also facilitate the formulation of rules for boundary matching and smoothing after concatenatingthe visyllables units. Ours is the first visyllable based speech animation system. The proposed technique iseasy to implement, effective for real-time as well as non real-time applications and results into realistic speechanimation. Categories and Subject Descriptors (according to ACM CCS): 1.3.7 [Computer Graphics]: Three-Dimensional Graphics and Realism [source] Enhanced process monitoring for wastewater treatment systemsENVIRONMETRICS, Issue 6 2008Chang Kyoo Yoo Abstract Wastewater treatment plants (WWTPs) remain notorious for poor data quality and sensor reliability problems due to the hostile environment, missing data problems and more. Many sensors in WWTP are prone to malfunctions in harsh environments. If a WWTP contains any redundancy between sensors, monitoring methods with sensor reconstruction such as the proposed one can yield a better monitoring efficiency than without a reconstruction scheme. An enhanced robust process monitoring method combined with a sensor reconstruction scheme to tackle the sensor failure problems is proposed for biological wastewater treatment systems. The proposed method is applied to a single reactor for high activity ammonia removal over nitrite (SHARON) process. It shows robust monitoring performance in the presence of sensor faults and produces few false alarms. Moreover, it enables us to keep the monitoring system running in the case of sensor failures. This guaranteed continuity of the monitoring scheme is a necessary development in view of real-time applications in full-scale WWTPs. Copyright © 2007 John Wiley & Sons, Ltd. [source] End-to-end network delay model for heavy-tailed environmentsEUROPEAN TRANSACTIONS ON TELECOMMUNICATIONS, Issue 5 2003David Muñoz-Rodríguez Adequate quality of Internet Protocol (IP) services demand low transmission delays. However, packets traveling in a network are subject to a variety of delays that degrade severely the quality of service in real-time applications. This paper presents a general packet jitter-assessment methodology for a multi-node path in the presence of heavy-tailed traffic. Using the extreme-value theory, it is shown that delay performance is governed by a proposed networking-processing factor |T|lambda dependent on the traffic characteristics, the processing time along the path segments and the number of nodes in a route. |T|lambda allows the establishment of design constraints and the definition of a feasibility space for a routing algorithm in order to guarantee a quality of service (QoS). Copyright © 2003 AEI. [source] TCP-friendly transmission of voice over IPEUROPEAN TRANSACTIONS ON TELECOMMUNICATIONS, Issue 3 2003F. Beritelli In the last few years an increasing amount of attention has been paid to technologies for the transmission of voice over IP (VoIP). At present, the UDP transport protocol is used to provide this service. However, when the same bottleneck link is shared with TCP flows, and in the presence of a high network load and congestion, UDP sources capture most of the bandwidth, strongly penalizing TCP sources. To solve this problem some congestion control should be introduced for UDP traffic as well, in such a way that this traffic becomes TCP-friendly. In this perspective, several TCP-friendly algorithms have been proposed in the literature. Among them, the most promising candidates for the immediate future are RAP and TFRC. However, although these algorithms were introduced to support real-time applications on the Internet, up to now the only target in optimizing them has been that of achieving fairness with TCP flows in the network. No attention has been paid to the applications using them, and in particular, to the quality of service (QoS) perceived by their users. The target of this paper is to analyze the problem of transmitting voice over IP when voice sources use one of these TCP-friendly algorithms. With this aim, a VoIP system architecture is introduced and the characteristics of each its elements are discussed. To optimize the system, a multirate voice encoder is used so as to be feasible to work over a TCP layer, and a modification of both RAP and TFRC is proposed. Finally, in order to analyze the performance of the proposed system architecture and to compare the modified RAP and TFRC with the original algorithms, the sources have been modeled with an arrival process modulated by a Markov chain, and the model has been used to generate traffic in a simulation study performed with the ns-2 network simulator. Copyright © 2003 AEI. [source] Design of a near-optimal adaptive filter in digital signal processor for active noise controlINTERNATIONAL JOURNAL OF ADAPTIVE CONTROL AND SIGNAL PROCESSING, Issue 1 2008S. M. Yang Abstract Adaptive filter has been applied in adaptive feedback and feedforward control systems, where the filter dimension is often determined by trial-and-error. The controller design based on a near-optimal adaptive filter in digital signal processor (DSP) is developed in this paper for real-time applications. The design integrates the adaptive filter and the experimental design such that their advantages in stability and robustness can be combined. The near-optimal set of controller parameters, including the sampling rate, the dimension of system identification model, the dimension (order) of adaptive controller in the form of an FIR filter, and the convergence rate of adaptation is shown to achieve the best possible system performance. In addition, the sensitivity of each design parameter can be determined by analysis of means and analysis of variance. Effectiveness of the adaptive controller on a DSP is validated by an active noise control experiment. Copyright © 2007 John Wiley & Sons, Ltd. [source] Online end-to-end quality of service monitoring for service level agreement managementINTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 4 2008Xiaoyuan Ta Abstract A major challenge in network and service level agreement (SLA) management is to provide Quality of Service (QoS) demanded by heterogeneous network applications. Online QoS monitoring plays an important role in the process by providing objective measurements that can be used for improving network design, troubleshooting and management. Online QoS monitoring becomes increasingly difficult and complex due to the rapid expansion of the Internet and the dramatic increase in the speed of network. Sampling techniques have been explored as a means to reduce the difficulty and complexity of measurement. In this paper, we investigate several major sampling techniques, i.e. systematic sampling, simple random sampling and stratified sampling. Performance analysis is conducted on these techniques. It is shown that stratified sampling with optimum allocation has the best performance. However, stratified sampling with optimum allocation requires additional statistics usually not available for real-time applications. An adaptive stratified sampling algorithm is proposed to solve the problem. Both theoretical analysis and simulation show that the proposed adaptive stratified sampling algorithm outperforms other sampling techniques and achieves a performance comparable to stratified sampling with optimum allocation. A QoS monitoring software using the aforementioned sampling techniques is designed and tested in various real networks. Copyright © 2007 John Wiley & Sons, Ltd. [source] Soft real-time communications over Bluetooth under interferences from ISM devicesINTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 10 2006J. L. Sevillano Abstract Bluetooth is a suitable technology to support soft real-time applications like multimedia streams at the personal area network level. In this paper, we analytically evaluate the worst-case deadline failure probability of Bluetooth packets under co-channel interference as a way to provide statistical guarantees when transmitting soft real-time traffic using ACL links. We consider the interference from independent Bluetooth devices, as well as from other devices operating in the ISM band like 802.11b/g and Zigbee. Finally, we show as an example how to use our model to obtain some results for the transmission of a voice stream. Copyright © 2006 John Wiley & Sons, Ltd. [source] Measurement-based admission control scheme with priority and service classes for application in wireless IP networks,INTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 6 2003Abbas Jamalipour Abstract Wireless IP networks will provide voice and data services using IP protocols over the wireless channel. But current IP is unsuitable to provide delay or loss bounds and insufficient to support diverse quality of service, both required by real-time applications. In order to support real-time applications in wireless IP networks, in this paper a measurement-based admission control (MBAC) with priority criteria and service classes is considered. First we have shown the suitability of MBAC in wireless IP networks by comparing its performance with a parameter-based scheme. Next, we have investigated the performance of strictly policy-based MBAC and policy plus traffic characteristic-based MBAC schemes in terms of (1) increasing the user mobility, (2) changing traffic parameters and (3) the presence of greedy users. The efficiency and fairness of each scheme are measured in terms of lower class new and handoff traffic performance. Copyright © 2003 John Wiley & Sons, Ltd. [source] Study of MANET routing protocols by GloMoSim simulatorINTERNATIONAL JOURNAL OF NETWORK MANAGEMENT, Issue 6 2005Ashwini K. Pandey This paper compares ad hoc on-demand distance vector (AODV), dynamic source routing (DSR) and wireless routing protocol (WRP) for MANETs to distance vector protocol to better understand the major characteristics of the three routing protocols, using a parallel discrete event-driven simulator, GloMoSim. MANET (mobile ad hoc network) is a multi-hop wireless network without a fixed infrastructure. Following are some of our key findings: (1) AODV is most sensitive to changes in traffic load in the messaging overhead for routing. The number of control packets generated by AODV became 36 times larger when the traffic load was increased. For distance vector, WRP and DSR, their increase was approximately 1.3 times, 1.1 times and 7.6 times, respectively. (2) Two advantages common in the three MANET routing protocols compared to classical distance vector protocol were identified to be scalability for node mobility in end-to-end delay and scalability for node density in messaging overhead. (3) WRP resulted in the shortest delay and highest packet delivery rate, implying that WRP will be the best for real-time applications in the four protocols compared. WRP demonstrated the best traffic scalability; control overhead will not increase much when traffic load increases. Copyright © 2005 John Wiley & Sons, Ltd. [source] An online active set strategy to overcome the limitations of explicit MPCINTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 8 2008H. J. Ferreau Abstract Nearly all algorithms for linear model predictive control (MPC) either rely on the solution of convex quadratic programs (QPs) in real time, or on an explicit precalculation of this solution for all possible problem instances. In this paper, we present an online active set strategy for the fast solution of parametric QPs arising in MPC. This strategy exploits solution information of the previous QP under the assumption that the active set does not change much from one QP to the next. Furthermore, we present a modification where the CPU time is limited in order to make it suitable for strict real-time applications. Its performance is demonstrated with a challenging test example comprising 240 variables and 1191 inequalities, which depends on 57 parameters and is prohibitive for explicit MPC approaches. In this example, our strategy allows CPU times of well below 100 ms per QP and was about one order of magnitude faster than a standard active set QP solver. Copyright © 2007 John Wiley & Sons, Ltd. [source] An efficient real-time method of analysis for non-coherent fault treesQUALITY AND RELIABILITY ENGINEERING INTERNATIONAL, Issue 2 2009Rasa Remenyte-Prescott Abstract Fault tree analysis is commonly used to assess the reliability of potentially hazardous industrial systems. The type of logic is usually restricted to AND and OR gates, which makes the fault tree structure coherent. In non-coherent structures not only components' failures but also components' working states contribute to the failure of the system. The qualitative and quantitative analyses of such fault trees can present additional difficulties when compared with the coherent versions. It is shown that the binary decision diagram (BDD) method can overcome some of the difficulties in the analysis of non-coherent fault trees. This paper presents the conversion process of non-coherent fault trees to BDDs. A fault tree is converted to a BDD that represents the system structure function (SFBDD). An SFBDD can then be used to quantify the system failure parameters but is not suitable for the qualitative analysis. Established methods, such as the meta-products BDD method, the zero-suppressed BDD (ZBDD) method and the labelled BDD (L-BDD) method, require an additional BDD that contains all prime implicant sets. The process using some of the methods can be time consuming and is not very efficient. In addition, in real-time applications the conversion process is less important and the requirement is to provide an efficient analysis. Recent uses of the BDD method are for real-time system prognosis. In such situations as events happen, or failures occur, the prediction of mission success is updated and used in the decision-making process. Both qualitative and quantitative assessments are required for the decision making. Under these conditions fast processing and small storage requirements are essential. Fast processing is a feature of the BDD method. It would be advantageous if a single BDD structure could be used for both the qualitative and quantitative analyses. Therefore, a new method, the ternary decision diagram (TDD) method, is presented in this paper, where a fault tree is converted to a TDD that allows both qualitative and quantitative analyses and no additional BDDs are required. The efficiency of the four methods is compared using an example fault tree library. Copyright © 2008 John Wiley & Sons, Ltd. [source] Online identification of nonlinear multivariable processes using self-generating RBF neural networksASIAN JOURNAL OF CONTROL, Issue 5 2010Karim Salahshoor Abstract This paper addresses the problem of online model identification for multivariable processes with nonlinear and time-varying dynamic characteristics. For this purpose, two online multivariable identification approaches with self-organizing neural network model structures will be presented. The two adaptive radial basis function (RBF) neural networks are called as the growing and pruning radial basis function (GAP-RBF) and minimal resource allocation network (MRAN). The resulting identification algorithms start without a predefined model structure and the dynamic model is generated autonomously using the sequential input-output data pairs in real-time applications. The extended Kalman filter (EKF) learning algorithm has been extended for both of the adaptive RBF-based neural network approaches to estimate the free parameters of the identified multivariable model. The unscented Kalman filter (UKF) has been proposed as an alternative learning algorithm to enhance the accuracy and robustness of nonlinear multivariable processes in both the GAP-RBF and MRAN based approaches. In addition, this paper intends to study comparatively the general applicability of the particle filter (PF)-based approaches for the case of non-Gaussian noisy environments. For this purpose, the Unscented Particle Filter (UPF) is employed to be used as alternative to the EKF and UKF for online parameter estimation of self-generating RBF neural networks. The performance of the proposed online identification approaches is evaluated on a highly nonlinear time-varying multivariable non-isothermal continuous stirred tank reactor (CSTR) benchmark problem. Simulation results demonstrate the good performances of all identification approaches, especially the GAP-RBF approach incorporated with the UKF and UPF learning algorithms. Copyright © 2010 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society [source] | |||||||||||||||||||||||||