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The diagnosis of C. difficile infection (CDI) - Two steps forwards?

JOURNAL OF INFECTION 2011年第5期63卷 398-399页

作者： Coia, John E. Eastaway, Anne Wiuff, Camilla Stobhill Hosp Scottish Salmonella Shigella & C Difficile Refere Glasgow G21 3UW Lanark Scotland Hlth Protect Scotland Cadogan Sq Glasgow G2 7HF Lanark Scotland

The use of toxin EIA assays as standalone tests for the diagnosis of CDI has been questioned on the basis of the potential for false-positive and false-negative results, particularly in low prevalence populations. Recent guidance has promoted the use of an algorithmic approach to address these concerns, although the optimal algorithm remains to be defined. The recent article by Goldenberg et al. sought to demonstrate that changing from toxin testing alone to an algorithm testing initially with glutamate dehydrogenase (GDH) and confirming with PCR for toxin B gene, was associated with an increase in laboratory positiv-ity rate from 2.2% to 5.6%. This was temporally associated with an increase in the Trust CDI rate reported under the Health Protection Agency's mandatory surveillance scheme, with the potential for associated financial penalties. It was concluded that increased positivity was attributable to enhanced sensitivity of detection, rather than a genuine increase in rates.

关键词： Diagnosis Glutamate Dehydrogenase algorithmic approach Biological Toxins Capacitive Discharge Ignition detection sensitivity optimization algorithms

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Sheet-Metal Press Line Parameter Tuning using a Combined DIRECT and Nelder-Mead Algorithm

Sheet-Metal Press Line Parameter Tuning using a Combined DIR...

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16th IEEE International Conference on Emerging Technologies and Factory Automation (ETFA)

作者： Svensson, Bo Nia, Nima K. Danielsson, Fredrik Lennartson, Bengt Univ West Dep Engn Sci SE-46186 Trollhattan Sweden Volvo Car Corp SE-29380 Olofstrom Sweden Chalmers Univ Technol SE-41296 Gothenburg Sweden

ISBN: (纸本)9781457700187

It is a great challenge to obtain an efficient algorithm for global optimisation of nonlinear, nonconvex and high dimensional objective functions. This paper shows how the combination of DIRECT and Nelder-Mead algorithms can improve the efficiency in the parameter tuning of a sheet-metal press line. A combined optimisation algorithm is proposed that determines and utilises all local optimal points from DIRECT algorithm as Nelder-Mead starting points. To reduce the total optimisation time, all Nelder-Mead optimisations can be executed in parallel. Additionally, a Collision Inspection Method is implemented in the simulation model to reduce the evaluation time. Altogether, this results in an industrially useful parameter tuning method. Improvements of an increased production rate of 7% and 40% smoother robot motions have been achieved.

关键词： press line Natural Increase Robot kinematics tuning Simulation models optimization algorithms local optimum Nelder-Mead Simplex Algorithm efficient algorithm Global optimization

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Rapid Weak-perspective Structure from Motion with Missing Data

Rapid Weak-perspective Structure from Motion with Missing Da...

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IEEE International Conference on Computer Vision (ICCV)

作者： Kazo, Csaba Hajder, Levente MTA SZTAKI Geometr Modelling & Comp Vis Lab H-1111 Budapest Hungary

ISBN: (纸本)9781467300636

3D reconstruction with missing data has been a very challenging computer vision task since the late 90s. This paper proposes the GPU-powered version of our weak-perspective Structure from Motion algorithm published in BMVC2008. Although this method is iterative, it is very rapid since all substeps in each iteration minimize the parameters optimally with respect to the reprojection error We demonstrate here in both synthetic and real tests that the use of the GPU significantly reduces the time demand of the algorithm. Real-time 3D reconstruction is possible if the parameters of the optimization algorithm are set properly.

关键词： missing data three-dimensional displays optimization algorithms images computer vision iterative methods Iterative SYNTHETICS

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FAST REGISTRATION OF 3D MULTIMODAL VOLUME IMAGES USING MUTUAL INFORMATION EXTRACTED FROM ORTHOGONAL PLANES

FAST REGISTRATION OF 3D MULTIMODAL VOLUME IMAGES USING MUTUA...

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6th International Symposium on Health Informatics and Bioinformatics (HIBIT)

作者： Deniz, Umut Sarnel, Haldun Dokuz Eylul Univ Dept Elect & Elect Kaynaklar Campus TR-35160 Izmir Turkey

ISBN: (纸本)9781467344319;9782467343944

Voxel-intensity based multimodal volume registration methods commonly use mutual information. Computing transformations and mutual information of volume is highly computation intensive and the registration method we propose in this paper reduces computation time considerably. The method uses information from only three orthogonal central planes of multimodal volume images. Performance results show that good and fast registration is achieved using suitably selected optimization algorithms.

关键词： Registration plane Orthogonal optimization algorithms computational time Fasting images

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Semi-decentralized Beamforming Coordination for Multiuser Two-Tier Networks

Semi-decentralized Beamforming Coordination for Multiuser Tw...

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5th International Conference on Signal Processing and Communication Systems (ICSPCS)

作者： Jeong, Youngmin Shin, Hyundong Quek, Tony Q. S. Kyung Hee Univ Dept Elect & Radio Engn Seoul 446701 South Korea Inst Infocomm Res Singapore Singapore

ISBN: (纸本)9781457711800

In this paper, we consider a downlink two-tier network comprising of a multiple-antenna macrocell base station and a single femtocell access point, each serving multiples users with a single antenna. In this scenario, we treat the total transmit power minimization problem and mean-square error balancing problem. In the presence of perfect channel state information (CSI), we formulate the optimization algorithms in a semi-decentralized manner by introducing the signal-to-Ieakage plus noise ratio criteria. Taking into account imperfect CSI, we also propose robust algorithms tailored by the worst-case design to mitigate the effect of channel uncertainty. Finally, numerical results are presented to validate our proposed algorithms.

关键词： TWO-LAYER optimization algorithms Beamforming worst case design

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Defending Mechanisms Against False-data Injection Attacks in the Power System State Estimation

Defending Mechanisms Against False-data Injection Attacks in...

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IEEE GLOBECOM Workshops (GC Wkshps)

作者： Bi, Suzhi Zhang, Ying Jun (Angela) Chinese Univ Hong Kong Dept Informat Engn Shatin Hong Kong Peoples R China

ISBN: (纸本)9781467300407

Accurate state estimation is of critical importance to maintain normal operating conditions of smart power grids. To ensure the integrity of state estimation, the current power grid systems use bad data detection (BDD) system to filter faulty measurements caused by device malfunctions or malicious attacks, etc. However, recent research shows that carefully synthesized false-data injection attacks can bypass the BDD system and thus introduce arbitrary errors to state estimates. In this paper, we investigate defending mechanisms against false-data injection attacks. Through protecting carefully selected meter measurements, no false-data injection attack can be launched to compromise any set of state estimates. We first derive a necessary and sufficient condition to select the protection measurements and analyze the properties of the optimal solution which protects the state estimates with minimum number of measurements. Based on the arguments, both optimal and reduced-complexity suboptimal algorithms are proposed. In particular, the suboptimal algorithm allows the system operator to protect the state estimates in arbitrary sequence according to their relative importance. Analysis and experiments show that it significantly reduces computational complexity, while yielding negligible performance degradation compared with the optimal algorithm. Our results here may find applications in the security upgrade projects of our current large-scale electrical power system towards smart power grids.

关键词： power system state estimation Smart grids State estimation degradation of performance Injections optimization algorithms power systems

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BEND STIFFENER DESIGN FOR UMBILICALS

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30th International Conference on Ocean, Offshore and Arctic Engineering

作者： Sodahl, Nils Ottesen, Torfinn Det Norske Veritas AS Oslo Norway Nexans Norway AS Halden Norway

ISBN: (纸本)9780791844366

A crucial design issue for compliant risers and umbilicals for dynamic applications is termination of the compliant structure to a rigid structure. A practical way to solve this problem is to introduce a properly designed bend stiffener to limit the stresses in the compliant structure due to bending at the supports. The bend stiffener provides a gradually increase of the bending stiffness from the rather small value of the compliant structure to a significantly larger value that can be rigidly connected without compromising the structural integrity of the compliant structure. Hence, the bend stiffener geometry needs to be designed to fulfill the design requirements for extreme as well as fatigue loading conditions for the compliant structure. Furthermore, it is required that the bend stiffener is as short as possible to limit costs, support forces, and enable fabrication and installation. The main focus of this paper is to outline an optimization scheme for bend stiffeners to meet design criteria for extreme loading conditions. Measures to provide an adequate fatigue performance of bend stiffeners are also discussed. The loads on the bend stiffener are governed by effective tension and relative angle close to the support (i.e. direction of effective tension relative to the longitudinal direction of the compliant structure at the support). Combinations of effective tension and relative angle aggregated for all relevant extreme load conditions define the design loads on the bend stiffener. The capacity of the compliant structure is governed by a capacity curve expressing the allowable curvature as function of the effective tension. A general optimization scheme is outlined accounting for a general description of the design loads as well as the capacity curve. The optimization methodology is based on a general purpose optimization algorithm utilizing a tailor made non-linear static finite element solver to describe the response of the bend stiffener and the compliant s

关键词： Computer software Finite element analysis Accounting Manufacturing Stiffness optimization Tension Fatigue Design Pipeline risers optimization algorithms Risers (Casting) Geometry Stress

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Hybrid Initialization for Non-convex Network Localization Problems

Hybrid Initialization for Non-convex Network Localization Pr...

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IEEE International Conference on Ultra-Wideband (ICUWB)

作者： Macagnano, Davide Destino, Giuseppe de Abreu, Giuseppe Thadeu Freitas Univ Oulu Ctr Wireless Commun Oulu 90014 Finland

ISBN: (纸本)9781457717642

Solving the distance-based network localization problem typically entails the formulation of an equivalent optimization problem which is either convex but sub-optimal, or optimal (i.e., maximum-likelihood) but non-convex. We show that the non-convexity implied by the choice of an optimal formulation need not be translated onto high computational complexity nor to performance degradation. To this end, we focus on an approach whereby low-complexity optimization algorithms are coupled with an efficient initialization which in turn, is formulated in terms of an Euclidean Distance Matrix (EDM) completion problem under the condition that the network is percolated (as required by Graph-based Completion). The resulting Hybrid Initialization scheme is shown to be sufficient to bring the performance of low-complexity algorithms such as the SMACOF and the NLS close to that of far more sophisticated alternatives such as the SDP.

关键词： Non-Convex initialization optimization algorithms maximum likelihood Service Discovery Protocol degradation of performance complexity classes Convexity

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Simplified Relay Algorithm for Two-Way MIMO Relay Communications

Simplified Relay Algorithm for Two-Way MIMO Relay Communicat...

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17th Asia-Pacific Conference on Communications (APCC)

作者： Rong, Yue Curtin Univ Dept Elect & Comp Engn Bentley WA 6102 Australia

ISBN: (纸本)9781457703881

In this paper, we investigate the challenging problem of joint source and relay optimization for two-way linear non-regenerative multiple-input multiple-output (MIMO) relay communication systems. First, a novel relay amplifying matrix is proposed which significantly reduces the computational complexity of the optimal relay design with only a marginal performance degradation. Interestingly, we show that the proposed relay matrix is indeed optimal for some special cases. Second, a semi-definite programming (SDP)-based source matrices optimization algorithm is developed. Then the source and relay optimization algorithms are carried out iteratively to minimized the sum mean-squared error of the signal waveform estimation in a two-way MIMO relay system. The performance of the proposed algorithm is demonstrated by numerical simulations.

关键词： relay signal waveform Relay Communication Bidirectional degradation of performance optimization algorithms complexity classes

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Study on the Parametric Optimal Design of a Different-Speed Mixer

Study on the Parametric Optimal Design of a Different-Speed ...

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Advanced Polymer Processing International Forum

作者： Fan Zhimin Hu Weifei Choi Dong-Hoon Xu Jun Qingdao Univ Sci & Technol Coll Electromech Engn Qingdao 266061 Peoples R China Hanyang Univ iDOT Seoul 133791 South Korea

ISBN: (纸本)9783037850299

The mechanical analysis and parametric optimal design of a different speed mixer is presented in this paper. After mechanics analysis, the total transmission power is derived. According to the realistic design requirements, several design constrains are also described. After established the whole optimization mathematical model of the different-speed mixer, Sequential Two-point Diagonal Quadratic Approximate optimization (STDQAO) algorithms is applied for the optimal design of the mixer, and obtained the minimum transmission power.

关键词： different-speed mixer optimal design optimization algorithms transmission power

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