3,159 research outputs found

    Evaluation of EIT systems and algorithms for handling full void fraction range in two-phase flow measurement

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    In the aqueous-based two-phase flow, if the void fraction of dispersed phase exceeds 0.25, conventional electrical impedance tomography (EIT) produces a considerable error due to the linear approximation of the sensitivity back-projection (SBP) method, which limits the EIT's wider application in the process industry. In this paper, an EIT sensing system which is able to handle full void fraction range in two-phase flow is reported. This EIT system employs a voltage source, conducts true mutual impedance measurement and reconstructs an online image with the modified sensitivity back-projection (MSBP) algorithm. The capability of the Maxwell relationship to convey full void fraction is investigated. The limitation of the linear sensitivity back-projection method is analysed. The MSBP algorithm is used to derive relative conductivity change in the evaluation. A series of static and dynamic experiments demonstrating the mean void fraction obtained using this EIT system has a good agreement with reference void fractions over the range from 0 to 1. The combination of the new EIT system and MSBP algorithm would significantly extend the applications of EIT in industrial process measurement

    Search for direct stau production in events with two hadronic tau-leptons in root s=13 TeV pp collisions with the ATLAS detector

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    A search for the direct production of the supersymmetric partners ofτ-leptons (staus) in final stateswith two hadronically decayingτ-leptons is presented. The analysis uses a dataset of pp collisions corresponding to an integrated luminosity of139fb−1, recorded with the ATLAS detector at the LargeHadron Collider at a center-of-mass energy of 13 TeV. No significant deviation from the expected StandardModel background is observed. Limits are derived in scenarios of direct production of stau pairs with eachstau decaying into the stable lightest neutralino and oneτ-lepton in simplified models where the two staumass eigenstates are degenerate. Stau masses from 120 GeV to 390 GeV are excluded at 95% confidencelevel for a massless lightest neutralino

    Search for chargino-neutralino production with mass splittings near the electroweak scale in three-lepton final states in √s=13 TeV pp collisions with the ATLAS detector

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    A search for supersymmetry through the pair production of electroweakinos with mass splittings near the electroweak scale and decaying via on-shell W and Z bosons is presented for a three-lepton final state. The analyzed proton-proton collision data taken at a center-of-mass energy of √s=13  TeV were collected between 2015 and 2018 by the ATLAS experiment at the Large Hadron Collider, corresponding to an integrated luminosity of 139  fb−1. A search, emulating the recursive jigsaw reconstruction technique with easily reproducible laboratory-frame variables, is performed. The two excesses observed in the 2015–2016 data recursive jigsaw analysis in the low-mass three-lepton phase space are reproduced. Results with the full data set are in agreement with the Standard Model expectations. They are interpreted to set exclusion limits at the 95% confidence level on simplified models of chargino-neutralino pair production for masses up to 345 GeV

    Search for new phenomena in final states with an energetic jet and large missing transverse momentum in pp collisions at √ s = 8 TeV with the ATLAS detector

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    Results of a search for new phenomena in final states with an energetic jet and large missing transverse momentum are reported. The search uses 20.3 fb−1 of √ s = 8 TeV data collected in 2012 with the ATLAS detector at the LHC. Events are required to have at least one jet with pT > 120 GeV and no leptons. Nine signal regions are considered with increasing missing transverse momentum requirements between Emiss T > 150 GeV and Emiss T > 700 GeV. Good agreement is observed between the number of events in data and Standard Model expectations. The results are translated into exclusion limits on models with either large extra spatial dimensions, pair production of weakly interacting dark matter candidates, or production of very light gravitinos in a gauge-mediated supersymmetric model. In addition, limits on the production of an invisibly decaying Higgs-like boson leading to similar topologies in the final state are presente

    Climate change and water resources in arid regions : uncertainty of the baseline time period

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    Recent climate change studies have given a lot of attention to the uncertainty that stems from general circulation models (GCM), greenhouse gas emission scenarios, hydrological models and downscaling approaches. Yet, the uncertainty that stems from the selection of the baseline period has not been studied. Accordingly, the main research question is as follows: What would be the differences and/or the similarities in the evaluation of climate change impacts between the GCM and the delta perturbation scenarios using different baseline periods? This article addresses this issue through comparison of the results of two different baseline periods, investigating the uncertainties in evaluating climate change impact on the hydrological characteristics of arid regions. The Lower Zab River Basin (Northern Iraq) has been selected as a representative case study. The research outcomes show that the considered baseline periods suggest increases and decreases in the temperature and precipitation (P), respectively, over the 2020, 2050 and 2080 periods. The two climatic scenarios are likely to lead to similar reductions in the reservoir mean monthly flows, and subsequently, their maximum discharge is approximately identical. The predicted reduction in the inflow for the 2080–2099 time period fluctuates between 31 and 49% based on SRA1B and SRA2 scenarios, respectively. The delta perturbation scenario permits the sensitivity of the climatic models to be clearly determined compared to the GCM. The former allows for a wide variety of likely climate change scenarios at the regional level and are easier to generate and apply so that they could complement the latter

    The Effect of Substrate Temperature on the Structural Properties of Spray Pyrolysed Lead Sulphide (PbS) Thin Films

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    Lead sulphide (PbS) films were prepared by the chemical spray pyrolysis technique using a solution of Lead nitrate and thiourea. PbS films were deposited (prepared) on glass substrate at varied temperature (250-350 oC). Effects of  substrate temperature on the structural characteristics of the films were studied. The X-ray diffraction patterns’ results reveal that the all of PbS films have a face centered cubic structure. The  X-ray diffraction study showed that irrespective of substrate temperature all the films exhibits a preferred orientation along the (200) plane. The degree of preferred orientation increased with the substrate temperature. It was observed that the increase  of the substrate temperature increase the diffraction peak intensity of (200) plane which resulted in increase in grain size  and good crystallinity of the films

    Climate change and anthropogenic intervention impact on the hydrologic anomalies in a semi-arid area : lower Zab river basin, Iraq

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    Climate change impact, drought phenomena and anthropogenic stress are of increasing apprehension for water resource managers and strategists, particularly in arid regions. The current study proposes a generic methodology to evaluate the potential impact of such changes at a basin scale. The Lower Zab River Basin located in the north of Iraq has been selected for illustration purposes. The method has been developed through evaluating changes during normal hydrological years to separate the effects of climate change and estimate the hydrologic abnormalities utilising Indicators of Hydrologic Alteration. The meteorological parameters were perturbed by applying adequate delta perturbation climatic scenarios. Thereafter, a calibrated rainfall-runoff model was used for streamflow simulations. Findings proved that climate change has a more extensive impact on the hydrological characteristics of the streamflow than anthropogenic intervention (i.e. the construction of a large dam in the catchment). The isolated baseflow is more sensitive to the precipitation variations than to the variations of the potential evapotranspiration. The current hydrological anomalies are expected to continue. This comprehensive basin study demonstrates how climate change impact, anthropogenic intervention as well as hydro-climatic drought and hydrological anomalies can be evaluated with a new methodology

    Team Learning: the Missing Construct from a Cross-Cultural Examination of Higher Education?

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    Team learning should be an important construct in organizational management research because team learning can enhance organizational learning and overall performance. However, there is limited understanding of how team learning works in different cultural contexts. Using an international comparative research approach, we developed a framework of antecedents and outcomes in the higher education context and tested it with samples from the UK and Vietnam. The results show that a common framework is applicable in the two different contexts, subject to slight modifications. However, this study does not find that team learning (measured via the proxy of “attitude towards team learning”) exhibits any statistically significant relationship as a predictor of the proposed outcomes. Other findings from this study on educational contexts are important not only to scholars in this field, but also for practicing managers, particularly those who study and operate in the extensive global market

    Molecular Characterization of β-Thalassemia Patients in Wasit Province, IRAQ

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    Background: Hemoglobin-associated disorder is a different group of recessive genetic diseases. which consist of the structural hemoglobin variants and the thalassemia.Aim of the study: - to characterize the spectrum of beta globin gene mutations  in patients with beta- thalassemia who are registered in thalassemia centers, Wasit, Iraq using PCR - based DNA diagnostic techniques.Patients and methods:The genomic DNA was extracted from 106 Iraqi patients with β-thalassemia major and intermedia from unrelated families and (50) healthy numbers as control were collected from Al-Karama  Teaching Hospital, in Wasit  province, to detect mutation using PCR - based DNA diagnostic techniques. .  Results: of 106 thalassemia patients, 35 (33%) of patients with no mutation detection, IVS 1.116 [T>G] mutation was detected in 42 patients ( 39.6%), followed by IVS 1.110 [G>A], which was detected in 11 (10.4%) patients.Conclusions: Many mutations recorded a high frequency due to close relative marriage. By analyzing many mutations in β-globin gene leading to defect in beta chains play crucial role in drawing mutation frequency and their distribution in our society. Keywords: thalassemia, mutation, DN

    Day care laparoscopic surgery in gynaecology at a dedicated unit in Nairobi, Kenya

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    Objective: To evaluate and audit the outcomes of Gynaecological Day care Laparoscopic Surgery inNairobi,KenyaDesign: Retrospective case analysisSetting: The International Centre for Minimal Access Surgery, NairobiSubjects: one thousand three hundred and seventy nine patients undergoing Laparoscopic SurgeryResults: Between January 2011 to December 2015 a total of 1,379 Laparoscopic procedures were undertaken during the reporting period of which 1,121 ( 88.5 % ) were done as day procedures. In total 137 patients ( 9.9 % ) spent one night at ICMAS, 21 ( 1.5 % ) were transferred to a Major Hospital and 41 patients (2.9 %) underwent conversion to Laparotomy. There were two Hospital re-admissions (0.14 % ) and one complication ( 0.07% ), a bladder injury was encountered.Conclusions: Daycare surgery is a continually evolving speciality being competently performed by several units by various disciplines world over , including Kenya. In recent years the complexity of the procedures has increased with a wider range of patients being considered for challenging surgeries including those presenting with acute conditions. Our experiences have been favourable
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