1,033 research outputs found

    Study of the wind speed, rainfall and storm surges for the Scheldt estuary in Belgium

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    The Belgian coast and the Scheldt estuary are important for the Belgian economy. Coastal flood risks tend to increase due to climate change. This study was set out to investigate the wind speed, surges and rainfall in the Scheldt estuary. The study explored the changes in mean and extreme winds according to the recent ENSEMBLES climate models and examined the dependency of extremes between surge with wind speed and surge with rainfall. The dependence analysis between surge and wind speed aimed to investigate whether climatic changes in wind speed can be transferred to changes in surge, while the existence of dependence between surge and rainfall would require climate scenarios for rainfall upstream in the Scheldt basin to be correlated with climate scenarios for the downstream surge boundary. A special dependence measure χ, developed by Buishand (1984) and Coles et al (2000) was followed. Data was extracted and processed using Matlab and CDO. The analysis of wind speeds showed that future wind speeds in the estuary (based on the climate models) will remain stable in comparison with the past wind speeds. Also, wind direction will be mainly from 180°-300°, although slight shifts might appear towards more frequent south western winds. From the study of dependency, there was no significant dependency between sea surge at Oostende coast and rainfall at different stations. The definition of significant dependency is strong or conservative. Above all, the extremes events are more or less dependent. While the study has not found significant changes in wind speed and only slight changes in wind direction, it is important to further investigate the impact of these changes on the Scheldt estuary using hydrodynamic models. The assessment of changes in extreme rainfall and sea surge need to be further studied

    Self modulated dynamics of a relativistic charged particle beam in plasma wake field excitation

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    Self modulated dynamics of a relativistic charged particle beam is reviewed within the context of the theory of plasma wake field excitation. The self-consistent description of the beam dynamics is provided by coupling the Vlasov equation with a Poisson-type equation relating the plasma wake potential to the beam density. An analysis of the beam envelope self-modulation is then carried out and the criteria for the occurrence of the instability are discussed thereby.Comment: This is a 10 pages manuscript which contain 4 figures. This manuscript is recently submitted in 'Nuclear Instruments and Methods in Physics Research Section A' as a proceeding of the conference 'EAAC 2015

    Sensor failure detection for jet engines

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    Revisions to the advanced sensor failure detection, isolation, and accommodation (DIA) algorithm, developed under the sensor failure detection system program were studied to eliminate the steady state errors due to estimation filter biases. Three algorithm revisions were formulated and one revision for detailed evaluation was chosen. The selected version modifies the DIA algorithm to feedback the actual sensor outputs to the integral portion of the control for the nofailure case. In case of a failure, the estimates of the failed sensor output is fed back to the integral portion. The estimator outputs are fed back to the linear regulator portion of the control all the time. The revised algorithm is evaluated and compared to the baseline algorithm developed previously

    Comparing Food and Cash Transfers to the Ultra-Poor in Bangladesh

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    "Bangladesh has some social safety net programs that transfer food to the poor, some that transfer cash, and some that provide a combination of both. This study evaluates the relative impacts of food and cash transfers on food security and livelihood outcomes among the ultra poor in Bangladesh. The programs impacts are evaluated according to various measures, including how well transfers are delivered; which transfers beneficiaries prefer; how accurately the programs target the extremely poor; effects on food security, livelihoods, and women’s empowerment; and cost effectiveness. The report identifies what has and has not worked in food and cash transfers and recommends ways of improving these programs. This study will be valuable to policymakers and others concerned with poverty reduction in Bangladesh and elsewhere." from textCash transfers, cost effectiveness, food security, Poverty, Poverty reduction, safety net programs, women empowerment,

    Folic acid, vitamin B12 and homocysteine levels following olanzapine administration in schizophrenia patients

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    The purpose of this study was to assess the levels of folic acid, vitamin B12 and homocysteine in the serum of schizophrenia patients (n=20) and to evaluate the effect of olanzapine on these biomarkers. The blood was also collected from the 10 healthy volunteers as control. Compared to control, the serum folic acid (p=0.005) and vitamin B12 levels (p=0.211) were higher in the schizophrenia patients, whereas no difference was evident in the serum homocysteine level. But significantly higher levels of serum folic acid (p=0.005), vitamin B12 (p=0.047) and significantly lower level of serum homocysteine (p=0.000) were observed after 10 weeks of olanzapine administration. BPRS score was reduced significantly after intervention. The Pearson correlation coefficient test showed a statistically not significant negative relationship between the serum folate, vitamin B12 and homocysteine levels. In conclusion, olanzapine can significantly elevate the  serum folic acid and vitamin B12 levels whereas it can lower the serum homocysteine level which may contribute to the improvement of symptoms of schizophrenia

    Sensor failure detection system

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    Advanced concepts for detecting, isolating, and accommodating sensor failures were studied to determine their applicability to the gas turbine control problem. Five concepts were formulated based upon such techniques as Kalman filters and a screening process led to the selection of one advanced concept for further evaluation. The selected advanced concept uses a Kalman filter to generate residuals, a weighted sum square residuals technique to detect soft failures, likelihood ratio testing of a bank of Kalman filters for isolation, and reconfiguring of the normal mode Kalman filter by eliminating the failed input to accommodate the failure. The advanced concept was compared to a baseline parameter synthesis technique. The advanced concept was shown to be a viable concept for detecting, isolating, and accommodating sensor failures for the gas turbine applications

    HYTESS: A hypothetical turbofan engine simplified simulation

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    A users manual for a hypothetical turbofan engine simplified simulation is presented. This digital simulation exists as FORTRAN source code. The program is self-contained and was developed to offer those interested in engine dynamics and controls research an efficient, realistic, and easily used engine simulation. The engine is modeled using a state space formulation. Matrix elements within the linear state space structure are nonlinear functions of various engine variables

    Dynamic management of UDDI registries in a wireless environment of web services

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    This paper presents mechanisms for managing the content of several Universal Description, Discovery, and Integration (UDDI) registries. These mechanisms are deployed in a wireless environment of Web services. By content, it is meant the announcements of Web services that providers submit to an UDDI registry. Unlike other initiatives in Web services field that consider a single UDDI registry and a wired communication infrastructure, this paper is concerned with the following aspects: several UDDI registries are deployed, there is no wired communication infrastructure between the UDDI registries, and absence of a centralized component that coordinates the UDDI registries. The solution presented integrates users and software agents into what we call messenger. Initially, software agents reside in users\u27 mobile devices and cache a description of the Web services that satisfy their users\u27 needs. Each time a user is in the vicinity of an UDDI registry, her software agent interacts with that registry so the details stored on Web services are submitted. © Springer-Verlag 2004

    Endobronchial tuberculosis simulating bronchial asthma

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