126 research outputs found

    Development of a simulation tool for flight dynamics and control investigations of articulated vtol unmanned aircraft

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    A simulation tool for flight dynamics and control investigations of three different Vertical Take Off and Landing (VTOL) unmanned aircraft configurations has been developed. A control concept has been proposed in order to take advantage of the fast response characteristics of the ordinary small engine/propeller propulsion systems in such aircraft, as well as replacing the complex rotors used previously in VTOL concepts for small unmanned aircraft. The simulation model has been established on the basis of the proposed concept so that it can also be used to study the feasibility of this idea. An Object-based methodology has been introduced so as to reduce the amount of aerodynamic required data for the simulation model. The equations of motion associated with the aircraft multibody system with ten degrees of freedom have been derived using the Newton-Euler method. The modelling of various subsystems including the propeller model, the airframe aerodynamics and the engine model has been carried out. A method for calculating the propellers' slipstream effects on the other components has been presented. Input data for the simulation model have been estimated, using different sources. The Advanced Continuous Simulation Language (ACSL) has been used for the programming of the mathematical model. A series of comprehensive tests have been carried out in order to demonstrate the validity of the simulation model. The ability of the simulation model to explain the aircraft modes of motion as well as to discover unknown nonlinear behaviours and to describe them has been demonstrated

    Application of FFTBM with signal mirroring to improve accuracy assessment of MELCOR code

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    This paper deals with the application of Fast Fourier Transform Base Method (FFTBM) with signal mirroring (FFTBM-SM) to assess accuracy of MELCOR code. This provides deeper insights into how the accuracy of MELCOR code in predictions of thermal-hydraulic parameters varies during transients. The case studied was modeling of Station Black-Out (SBO) accident in PSB-VVER integral test facility by MELCOR code. The accuracy of this thermal-hydraulic modeling was previously quantified using original FFTBM in a few number of time-intervals, based on phenomenological windows of SBO accident. Accuracy indices calculated by original FFTBM in a series of time-intervals unreasonably fluctuate when the investigated signals sharply increase or decrease. In the current study, accuracy of MELCOR code is quantified using FFTBMSM in a series of increasing time-intervals, and the results are compared to those with original FFTBM. Also, differences between the accuracy indices of original FFTBM and FFTBM-SM are investigated and correction factors calculated to eliminate unphysical effects in original FFTBM. The main findings are: (1) replacing limited number of phenomena-based time-intervals by a series of increasing time-intervals provides deeper insights about accuracy variation of the MELCOR calculations, and (2) application of FFTBM-SM for accuracy evaluation of the MELCOR predictions, provides more reliable results than original FFTBM by eliminating the fluctuations of accuracy indices when experimental signals sharply increase or decrease. These studies have been performed in the framework of a research project, aiming to develop an appropriate accident management support tool for Bushehr nuclear power plant. 2016 Elsevier B.V. All rights reserved

    The road to developing economically feasible plans for green, comfortable and energy efficient buildings

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    Owing to the current challenges in energy and environmental crises, improving buildings, as one of the biggest concerns and contributors to these issues, is increasingly receiving attention from the world. Due to a variety of choices and situations for improving buildings, it is important to review the building performance optimization studies to find the proper solution. In this paper, these studies are reviewed by analyzing all the different key parameters involved in the optimization process, including the considered decision variables, objective functions, constraints, and case studies, along with the software programs and optimization algorithms employed. As the core literature, 44 investigations recently published are considered and compared. The current investigation provides sufficient information for all the experts in the building sector, such as architects and mechanical engineers. It is noticed that EnergyPlus and MATLAB have been employed more than other software for building simulation and optimization, respectively. In addition, among the nine different aspects that have been optimized in the literature, energy consumption, thermal comfort, and economic benefits are the first, second, and third most optimized, having shares of 38.6%, 22.7%, and 17%, respectively

    Determining infertility treatment costs and out of pocket payments imposed on couples

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    Background: Infertility and infertility treatment costs are considered as one of the main challenges that human society increasingly face with.Objective: To determine infertility treatment costs and out of pocket expenditures imposed on couples referred to infertility treatment center in Yazd, Iran.Design: A descriptive cross sectional studySubjects: A total of 216 couples were selected and contributed in the study through convenient sampling method.Setting: Telephone interviews with couples and medical documents review were also used to ensure the accuracy of collected information.Results: Lost opportunity, direct and indirect costs were 5.562.526, 37.812.354 and 11.125.395 rial respectively (1USD=33,000 rial). Among direct costs the most and the least expenditures belonged to surgery (24.042.137 rial) and clinical visits (174.053 rial). The greatest portion of indirect costs was related to accommodation expenses and the least was due to travel costs (4.898.099 and 2.738.491 rial). Findings confirmed a significant statistical relation between indirect costs and patients’ living place, also a significant relation between lost opportunity cost and patients’ occupation (P<0.05).Conclusion: Due to the high expenditures related to infertility treatment services also lack of insurance coverage, policy makers should pay a particular attention on meeting the reproductive health needs of a society

    A suggested prototype for assessing bone health

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    Background- Osteoporosis is becoming a health concern worldwide. Considering the fact that prevention plays an important role in reducing the burden of this silent disease and in view of the limited resources available, many countries have adopted certain programs to fight osteoporosis through shifting their attention towards at-risk individuals. The Iranian Multicenter Osteoporosis Study (IMOS) is one of these programs. The program aims to assess bone health and the prevalence of vitamin D deficiency in different parts of Iran with various altitudes, latitudes and lifestyle habits in a way that the results could be generalized to the country. Method- The present article presents the protocol used in the third phase of the study. It was designed based on the experiences gathered in the previous phases to overcome the shortcomings particularly subject loss. The questionnaire applied in this study was developed based on a thorough literature review of the risk factors and secondary causes of osteoporosis and was approved by an expert panel. It should be added that while the majority of the existing studies aim to study a certain aspect of osteoporosis, the present protocol provides the information needed for policy makers and researchers to study different osteoporosis-related issues. Conclusion- The authors believe the protocol, to be implemented with small modifications, can help policymakers in different parts of the world, particularly developing countries, gather accurate information on different aspects of bone health at the national level. © 2015, Academy of Medical Sciences of I.R. Iran. All rights reserved

    Future Research in Health Information Technology: A Review

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    INTRODUCTION: Currently, information technology is considered an important tool to improve healthcare services. To adopt the right technologies, policy makers should have adequate information about present and future advances. This study aimed to review and compare studies with a focus on the future of health information technology. METHOD: This review study was completed in 2015. The databases used were Scopus, Web of Science, ProQuest, Ovid Medline, and PubMed. Keyword searches were used to identify papers and materials published between 2000 and 2015. Initially, 407 papers were obtained, and they were reduced to 11 papers at the final stage. The selected papers were described and compared in terms of the country of origin, objective, methodology, and time horizon. RESULTS: The papers were divided into two groups: those forecasting the future of health information technology (seven papers) and those providing health information technology foresight (four papers). The results showed that papers related to forecasting the future of health information technology were mostly a literature review, and the time horizon was up to 10 years in most of these studies. In the health information technology foresight group, most of the studies used a combination of techniques, such as scenario building and Delphi methods, and had long-term objectives. CONCLUSION: To make the most of an investment and to improve planning and successful implementation of health information technology, a strategic plan for the future needs to be set. To achieve this aim, methods such as forecasting the future of health information technology and offering health information technology foresight can be applied. The forecasting method is used when the objectives are not very large, and the foresight approach is recommended when large-scale objectives are set to be achieved. In the field of health information technology, the results of foresight studies can help to establish realistic long-term expectations of the future of health information technology

    Future Research in Health Information Technology: A Review

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    INTRODUCTION: Currently, information technology is considered an important tool to improve healthcare services. To adopt the right technologies, policy makers should have adequate information about present and future advances. This study aimed to review and compare studies with a focus on the future of health information technology. METHOD: This review study was completed in 2015. The databases used were Scopus, Web of Science, ProQuest, Ovid Medline, and PubMed. Keyword searches were used to identify papers and materials published between 2000 and 2015. Initially, 407 papers were obtained, and they were reduced to 11 papers at the final stage. The selected papers were described and compared in terms of the country of origin, objective, methodology, and time horizon. RESULTS: The papers were divided into two groups: those forecasting the future of health information technology (seven papers) and those providing health information technology foresight (four papers). The results showed that papers related to forecasting the future of health information technology were mostly a literature review, and the time horizon was up to 10 years in most of these studies. In the health information technology foresight group, most of the studies used a combination of techniques, such as scenario building and Delphi methods, and had long-term objectives. CONCLUSION: To make the most of an investment and to improve planning and successful implementation of health information technology, a strategic plan for the future needs to be set. To achieve this aim, methods such as forecasting the future of health information technology and offering health information technology foresight can be applied. The forecasting method is used when the objectives are not very large, and the foresight approach is recommended when large-scale objectives are set to be achieved. In the field of health information technology, the results of foresight studies can help to establish realistic long-term expectations of the future of health information technology

    Pharmacological treatments of COVID-19

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    The viral infection due to the new coronavirus or coronavirus disease 2019 (COVID-19), which was reported for the first time in December 2019, was named by the World Health Organization (WHO) as Severe Acute Respiratory Syndrome-Coronavirus-2 (SARS-CoV2), because of the very similar genome and also its related symptoms to SARS-CoV1. The ongoing COVID-19 pandemic with significant mortality, morbidity, and socioeconomic impact is considered by the WHO as a global public health emergency. Since there is no specific treatment available for SARS-CoV2 infection, and or COVID-19, several clinical and sub-clinical studies are currently undertaken to find a gold-standard therapeutic regimen with high efficacy and low side effect. Based on the published scientific evidence published to date, we summarized herein the effects of different potential therapies and up-to-date clinical trials. The review is intended to help readers aware of potentially effective COVID-19 treatment and provide useful references for future studies. © 2020, Maj Institute of Pharmacology Polish Academy of Sciences

    High-Density SNP Mapping of the HLA Region Identifies Multiple Independent Susceptibility Loci Associated with Selective IgA Deficiency

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    Selective IgA deficiency (IgAD; serum IgA<0.07 g/l) is the most common form of human primary immune deficiency, affecting approximately 1∶600 individuals in populations of Northern European ancestry. The polygenic nature of IgAD is underscored by the recent identification of several new risk genes in a genome-wide association study. Among the characterized susceptibility loci, the association with specific HLA haplotypes represents the major genetic risk factor for IgAD. Despite the robust association, the nature and location of the causal variants in the HLA region remains unknown. To better characterize the association signal in this region, we performed a high-density SNP mapping of the HLA locus and imputed the genotypes of common HLA-B, -DRB1, and -DQB1 alleles in a combined sample of 772 IgAD patients and 1,976 matched controls from 3 independent European populations. We confirmed the complex nature of the association with the HLA locus, which is the result of multiple effects spanning the entire HLA region. The primary association signal mapped to the HLA-DQB1*02 allele in the HLA Class II region (combined P = 7.69×10−57; OR = 2.80) resulting from the combined independent effects of the HLA-B*0801-DRB1*0301-DQB1*02 and -DRB1*0701-DQB1*02 haplotypes, while additional secondary signals were associated with the DRB1*0102 (combined P = 5.86×10−17; OR = 4.28) and the DRB1*1501 (combined P = 2.24×10−35; OR = 0.13) alleles. Despite the strong population-specific frequencies of HLA alleles, we found a remarkable conservation of these effects regardless of the ethnic background, which supports the use of large multi-ethnic populations to characterize shared genetic association signals in the HLA region. We also provide evidence for the location of association signals within the specific extended haplotypes, which will guide future sequencing studies aimed at characterizing the precise functional variants contributing to disease pathogenesis
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