812 research outputs found

    Low-Complexity Sub-band Digital Predistortion for Spurious Emission Suppression in Noncontiguous Spectrum Access

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    Noncontiguous transmission schemes combined with high power-efficiency requirements pose big challenges for radio transmitter and power amplifier (PA) design and implementation. Due to the nonlinear nature of the PA, severe unwanted emissions can occur, which can potentially interfere with neighboring channel signals or even desensitize the own receiver in frequency division duplexing (FDD) transceivers. In this article, to suppress such unwanted emissions, a low-complexity sub-band DPD solution, specifically tailored for spectrally noncontiguous transmission schemes in low-cost devices, is proposed. The proposed technique aims at mitigating only the selected spurious intermodulation distortion components at the PA output, hence allowing for substantially reduced processing complexity compared to classical linearization solutions. Furthermore, novel decorrelation based parameter learning solutions are also proposed and formulated, which offer reduced computing complexity in parameter estimation as well as the ability to track time-varying features adaptively. Comprehensive simulation and RF measurement results are provided, using a commercial LTE-Advanced mobile PA, to evaluate and validate the effectiveness of the proposed solution in real world scenarios. The obtained results demonstrate that highly efficient spurious component suppression can be obtained using the proposed solutions

    Automatic Software Test Data Generation for Spanning Sets Coverage Using Genetic Algorithms

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    Software testing takes a considerable amount of time and resources spent on producing software. Therefore, it would be useful to have ways to reduce the cost of software testing. The new concepts of spanning sets of entities suggested by Marré and Bertolino are useful for reducing the cost of testing. In fact, to reduce the testing effort, the generation of test data can be targeted to cover the entities in the spanning set, rather than all the entities in the tested program. Marré and Bertolino presented an algorithm based on the subsumption relation between entities to find spanning sets for a family of control flow and data flow-based test coverage criteria. This paper presents a new general technique for the automatic test data generation for spanning sets coverage. The proposed technique applies to the algorithm proposed recently by Marré and Bertolino to automatically generate the spanning sets of program entities that satisfy a wide range of control flow and data flow-based test coverage criteria. Then, it uses a genetic algorithm to automatically generate sets of test data to cover these spanning sets. The proposed technique employed the concepts of spanning sets to limit the number of test cases, guide the test case selection, overcome the problem of the redundant test cases and automate the test path generation

    Myringoplasty in children: Retrospective analysis of 60 cases

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    Myringoplasty or type 1 tympanoplasty aims the restoration of the anatomic integrity of the tympanic membrane; it's a very common surgery in otology. The objective was to evaluate the anatomic and functional results of this surgery in children using the retro-auricular approach. Sixty young patients with diagnosis of simple tympanic perforation were evaluated; these patients underwent myringoplasty by a retro-auricular approach (underlay technique) between November 2010 and May 2013. It's a retrospective evaluation of the anatomic and functional results of theses myringoplasties. Mean age at surgery was 8, 5 years old, cartilage was used as graft in our entire patient, closure of perforation was successful in 48 cases (80%), and audiometric results showed functional improvement in 27 (45%) patients, no significant change was noted in the remaining patients. The results of myringoplasty in children seem worse than those in adults. However, a large study with a long follow up is warranted in order to come to definitive conclusions

    Enhancing radial distribution system performance by optimal placement of DSTATCOM

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    In this paper, A novel modified optimization method was used to find the optimal location and size for placing distribution Static Compensator in the radial distribution test feeder in order to improve its performance by minimizing the total power losses of the test feeder, enhancing the voltage profile and reducing the costs. The modified grey wolf optimization algorithm is used for the first time to solve this kind of optimization problem. An objective function was developed to study the radial distribution system included total power loss of the system and costs due to power loss in system. The proposed method is applied to two different test distribution feeders (33 bus and 69 bus test systems) using different Dstatcom sizes and the acquired results were analyzed and compared to other recent optimization methods applied to the same test feeders to ensure the effectiveness of the used method and its superiority over other recent optimization mehods. The major findings from obtained results that the applied technique found the most minimized total power loss in system ,the best improved voltage profile and most reduction in costs due power loss compared to other methods

    Micromechanical based model for predicting aged rubber fracture properties

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    Environmental aging induces a slow and irreversible alteration of the rubber material’s macromolecular network. This alteration is triggered by two mechanisms which act at the microscale: crosslinking and chain scission. While crosslinking induces an early hardening of the material, chain scission leads to the occurrence of dangling chains responsible of the damage at the macromolecular scale. Consequently, the mechanical behavior as well as the fracture properties are affected. In this work, the effect of aging on the mechanical behavior up to fracture of elastomeric materials and the evolution of their fracture properties are first experimentally investigated. Further, a modeling attempt using an approach based upon a micro-mechanical but physical description of the aging mechanisms is proposed to predict the mechanical and fracture properties evolution of aged elastomeric materials. The proposed micro-mechanical model incorporates the concepts of residual stretch associated with the crosslinking mechanism and a so-called “healthy” elastic active chain (EAC) density associated with chain scission mechanism. The validity of the proposed approach is assessed using a wide set of experimental data either generated by the authors or available in the literature

    OXA-163-producing Klebsiella pneumoniae in Cairo, Egypt, in 2009 and 2010.

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    Two genetically unrelated OXA-163-carrying Klebsiella pneumoniae strains were identified from two infection cases in June 2009 and May 2010 in Cairo, Egypt. OXA-163-producing Enterobacteriaceae had been previously reported in Argentina only. Both patients had no history of travel abroad. The emergence of this newly recognized OXA-48-related \u3b2-lactamase able to hydrolyze cephalosporins and carbapenems is especially worrying in a geographic area where OXA-48 is endemic and effective surveillance for antibiotic resistance is largely unaffordable

    Instantaneous blowup and singular potentials on Heisenberg groups

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    In this paper we generalize the instantaneous blowup result from [3] and [15] to the heat equation perturbed by singular potentials on the Heisenberg group

    Enhancing the evaporative cooling performance of fan-pad system using alternative pad materials and water film over the greenhouse roof

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    Greenhouse technology is a viable option for sustainable crop production in the regions of adverse climatic conditions.  During hot seasons the heat input to a greenhouse causes the internal temperature to exceed its optimal value.  The present study was devoted to construct an evaporative cooling system to reduce heat stress inside a greenhouse.  Two identical small-scale greenhouses were designed, constructed, and installed on an open roof of a domestic house.  The two greenhouses were cooled using fan-pad system.  In addition, a thin water film was applied on the roof of one greenhouse to study the effect of roof water film and fan-pad (combined system) on the cooling performance.  The two cooling systems were compared under the same condition.  Three new evaporative cooling pads represented by Cryperus Alopecuroides Rottb (Samar), Cyerus Alternifolius (Purdy) and Cyperus Rotundus l (Nut-grass or Se'd) were adapted and evaluated.  Three pad face air velocities ranged between 0.45 and 1.01 m s-1 and two thicknesses of 10 and 15 cm were used in the investigation of the cooling performance criteria.  Results showed that the proposed cooling pads in the suggested evaporative cooling systems were able to maintain acceptable microclimatic conditions for greenhouse models.  Se'd pad material proved more efficiency in temperature reduction.  It was revealed that the temperature inside the greenhouse operated under the combination of roof water flow and fan-pad system was less than that for fan-pad greenhouse by about 1.1 to 5.44° C in the morning and afternoon respectively.  The air relative humidity was increased due to humid effect provided by cooling system which protects crops from excessive transpiration and crop damage.  The daily average cooling efficiencies of 88.4, 83.1 and 79.6% were obtained for Se'd, Purdy and Samar, respectively during testing days inside the combined system at 15 cm pad thickness and 0.45 m s-1 pad face air velocity.  The Se'd pad material showed the highest efficiency as compared to other pad materials and could be used as an alternative pad material.   Keywords: greenhouse, evaporative cooling, fan-pad system, pad material, roof water flo

    Une tumeur du vagin à ne pas méconnaitre, l’adénocarcinome mésonephrique: à propos d’un cas et revue de la literature

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    L'adénocarcinome mésonéphrique du vagin est une tumeur maligne extrêmement rare avec uniquement trois cas publiés dans la littérature jusqu'à maintenant. Il dérive des reliquats embryonnaires des canaux mésonéphriques au niveau du vagin. Nous rapportons un cas d'adénocarcinome mésonéphrique du vagin survenant chez une femme de 50 ans, et révélé par une masse polyploïde du vagin. L'IRM a montré un envahissement du périnée et de la branche inférieure du pubis. L'étude anatomo-pathologique était en faveur d'un adénocarcinome mésonéphrique dont les cellules tumorales expriment la pancytokératine et le CD10. Elles ne sont pas marquées par les anticorps anti récepteurs ostrogéniques et progestatifs. La patiente a été adressée pour radiothérapie avant la prise en charge chirurgicale. Les auteurs soulignent à travers cette observation les aspects étiopathogéniques, histologiques et thérapeutiques de cette tumeur rare

    First Case Report of Primary Testicular Diffuse Large B-Cell Lymphoma from the Western Region of Saudi Arabia

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    Primary testicular lymphoma (PTL) represents 1-2% of all types of non-Hodgkin lymphomas (NHLs) and 1-10% of testicular neoplasms. Up to the best of my knowledge, this is the first case of PTL of the diffuse large B-cell lymphoma (DLBCL) in a 60-year-old man presented with a painless mass in the left testis as revealed by physical examination in a tertiary care hospital in Al-Madinah Al-Munwarah in the western region of the Kingdom of Saudi Arabia (KSA). Radiological examination revealed a large well-defined heterogeneous predominantly hypo-echoic mass with increased vascularity in the upper portion of the testis. On the other hand, histopathological examination revealed a tumor involving the whole left testis, which was large (measuring 6 3.5  3.3 cm), solid and dark red with focal areas of hemorrhage and epididymal infiltration. Immunohistochemistry showed positivity of leucocyte common antigen (LCA), pan B-cell marker (CD20) and negativity of pan T-cell marker (CD3). Other immunohistochemical markers such as CD10, placental alkaline phosphatase (PLAP), cytokeratin, vimentin, desmin and S100 protein were also negative. However, there was a marked expression of Ki67 and Bcl2 markers. Accordingly, the diagnosis of DLBCL was established. The tumor was classified as stage I according to the Ann Arbor system. The case was treated by orchiectomy followed by prophylactic anthracycline-based chemotherapy and irradiation of the contralateral testis and central nervous system
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