352 research outputs found

    Disruption Management Optimization for Military Logistics

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    Part 3: Financial and Management Applications of AIInternational audienceTo ensure long-term competitiveness, companies try to maintain a high level of agility, flexibility and responsiveness. In many domains, hierarchical SCs are considered as dynamic systems that deal with many perturbations. In this paper, we handle a specific type of supply chain: a Crisis Management Supply Chain (CMSC). Supply during peacetime can be managed by proactive logistics plans and classic supply chain management techniques to guaranty the availability of required needs. However, in case of perturbations (time of war, natural disasters...) the need for support increases dramatically and logistics plans need to be adjusted rapidly. Subjective variables like risk, uncertainty and vulnerability will be used in conjunction with objective variables such as inventory levels, delivery times and financial loss to determine preferred courses of action

    PON Data Centre Design with AWGR and Server Based Routing

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    Passive Optical Networks (PONs) with their proven performance in access networks can provide solutions to the challenges facing modern data centres. In this paper, we study a PON architecture where Arrayed Waveguide Grating Routers (AWGRs) and servers are used to route traffic. We optimize the wavelength routing and assignment in the design and show through a benchmark study that the PON data centre architecture reduces the power consumption by 83% compared to the Fat-Tree architecture and 93% compared to the BCube architecture

    PON Data Centre Design with AWGR and Server Based Routing

    Get PDF
    Passive Optical Networks (PONs) with their proven performance in access networks can provide solutions to the challenges facing modern data centres. In this paper, we study a PON architecture where Arrayed Waveguide Grating Routers (AWGRs) and servers are used to route traffic. We optimize the wavelength routing and assignment in the design and show through a benchmark study that the PON data centre architecture reduces the power consumption by 83% compared to the Fat-Tree architecture and 93% compared to the BCube architecture

    Health Electroencephalogram epileptic classification based on Hilbert probability similarity

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    This paper has proposed a new classification method based on Hilbert probability similarity to detect epileptic seizures from electroencephalogram (EEG) signals. Hilbert similarity probability-based measure is exploited to measure the similarity between signals. The proposed system consisted of models based on Hilbert probability similarity (HPS) to predict the state for the specific EEG signal. Particle swarm optimization (PSO) has been employed for feature selection and extraction. Furthermore, the used dataset in this study is Bonn University's publicly available EEG dataset. Several metrics are calculated to assess the performance of the suggested systems such as accuracy, precision, recall, and F1-score. The experimental results show that the suggested model is an effective tool for classifying EEG signals, with an accuracy of up to 100% for two-class status

    Scatter reduction for grid-less mammography using the convolution-based image post-processing technique

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    Mammography examinations are highly affected by scattered radiation, as it degrades the quality of the image and complicates the diagnosis process. Anti-scatter grids are currently used in planar mammography examinations as the standard physical scattering reduction technique. This method has been found to be inefficient, as it increases the dose delivered to the patient, does not remove all the scattered radiation and increases the price of the equipment. Alternative scattering reduction methods, based on post-processing algorithms, are being investigated to substitute anti-scatter grids. Methods such as the convolution-based scatter estimation have lately become attractive as they are quicker and more flexible than pure Monte Carlo (MC) simulations. In this study we make use of this specific method, which is based on the premise that the scatter in the system is spatially diffuse, thus it can be approximated by a two-dimensional low-pass convolution filter of the primary image. This algorithm uses the narrow pencil beam method to obtain the scatter kernel used to convolve an image, acquired without anti-scatter grid. The results obtained show an image quality comparable, in the worst case, to the grid image, in terms of uniformity and contrast to noise ratio. Further improvement is expected when using clinically-representative phantoms

    Optimisation of one stage electrostatic precipitator for welding fume filtration

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    AbstractIn addition to huge installations of electrostatic precipitators (ESP), as those employed for dust filtration in blast furnaces and cement factories, there are also small devices as the ones used for fume filtration in welding shops. The aim of this paper is to optimize the geometric characteristics and the electric operating conditions of a “one-stage” precipitator intended for the filtration of welding fumes. The experimental bench is composed of 2 units, each consisting in an horizontal wire (tungsten, diameter 0.1 mm), energized from a high-voltage supply (+15 kV, 5 mA), and equally distant from two vertical plate electrodes (aluminium, length 200 mm × variable width) connected to the ground. Two “one-factor-at-a-time” experiments paved the way for a composite experimental design that enabled the optimization of ESP geometry, i.e. the inter-electrode interval and width of the collecting electrodes

    Radioactivity Distribution In Surface And Core Sediment Of The Central Part Of The Algerian Coast: An Estimation Of The Recent Sedimentation Rate

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    Sediment core samples and marine surface sediments of identical composition, mostly muddy, were collected using a Van Veen type grab and a box corer on board the M.S. Benyahia research vessel (ISMAL), along the Algerian littoral, between Algiers (36Ζ49.9 N/ 03Ζ 02.3 E) and Cherchell (36Ζ 39.4 N/ 02Ζ 12.4 E), during a sampling cruise in September 1997. The samples were analysed to determine the activity concentration of natural radionuclides (uranium and thorium series and 40 K as well) and artificial radionuclides ( 137 Cs and Pu isotopes), using a direct gamma spectrometry for gamma emitters and radiochemical separations and alpha spectrometry for alpha emitters. The horizontal and vertical distribution of the examined radionuclides were studied in the surface and core samples and an effort to estimate the sedimentation rate was attempted.The measured values range was: 17 - 26 Bq/Kg dry for uranium series radioisotopes, 18 – 32 Bq/Kg dry for thorium series radioisotopes, 311 - 690 Bq/Kg dry for 40 K, 0.4 - 11 Bq/Kg dry, for 137 Cs and 0.4 – 1.0 Bq/Kg dry for 239 + 240 Pu

    A semi-empirical model for scatter field reduction in digital mammography

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    X-ray mammography is the gold standard technique in breast cancer screening programmes. One of the main challenges that mammography is still facing is scattered radiation, which degrades the quality of the image and complicates the diagnosis process. Anti-scatter grids, the main standard physical scattering reduction technique, have some unresolved challenges as they increase the dose delivered to the patient, do not remove all the scattered radiation and increase the cost of the equipment. Alternative scattering reduction methods based on post-processing algorithms, have lately been under investigation. This study is concerned with the use of image post-processing to reduce the scatter contribution in the image, by convolving the primary plus scatter image with kernels obtained from simplified Monte Carlo (MC) simulations. The proposed semi-empirical approach uses up to five thickness-dependant symmetric kernels to accurately estimate the scatter contribution of different areas of the image. Single breast thickness-dependant kernels can over-estimate the scatter signal up to 60%, while kernels adapting to local variations have to be modified for each specific case adding high computational costs. The proposed method reduces the uncertainty to a 4%-10% range for a 35-70 mm breast thickness range, making it a very efficient, case-independent scatter modelling technique. To test the robustness of the method, the scattered corrected image has been successfully compared against full MC simulations for a range of breast thicknesses. In addition, clinical images of the 010A CIRS phantom were acquired with a mammography system with and without the presence of the anti-scatter grid. The grid-less images were post-processed and their quality was compared against the grid images, by evaluating the contrast-to-noise ratio and variance ratio using several test objects, which simulate calcifications and tumour masses. The results obtained show that the method reduces the scatter to similar levels than the anti-scatter grids
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