• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 7
  • 6
  • 2
  • 1
  • Tagged with
  • 16
  • 16
  • 8
  • 4
  • 3
  • 3
  • 3
  • 3
  • 3
  • 3
  • 3
  • 3
  • 2
  • 2
  • 2
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

The realization of a study on the current and future trends of the cost of access to space for CubeSat missions.

Phen, Alice January 2022 (has links)
The increasing number of space-related applications and the development of miniaturized satellites (sometimes called CubeSats) recently became an exciting area in modern space science. Due to their diverse applications, smaller size, and low development cost. More sophisticated CubeSat missions have been recently introduced, signaling that CubeSats have started to progress from solely technical demonstration platforms to providing opportunities for low-cost actual research missions with a highly promising benefit in terms of commercial revenue. Despite major advancements in CubeSat technology, there is still a range of fundamental concerns regarding CubeSat barriers, pitfalls, and commercial effects. From both an academic and an industrial perspective, this report offers a thorough overview of various facets of CubeSat manufacturing and launch costs. The latest trends in CubeSat were discussed as well as an analysis of the launch cost and other variables that could influence the mission. An information-gathering approach was used from various proposed and launched missions, including journal articles, the official space mission webpages, and other publicly accessible satellite databases. Using data collected from various sources, we found that the latest launching price for future missions is influenced and modeled by various reasons. The Liquid propellant, miniaturized thrusters for small satellites, and modernized payload carriers could play a part in lowering the cost of potential launches. For instance, the RP-1 fuel used in Falcon 9 is expandable and reusable, increasing launch opportunities and low per-unit launch costs. Likewise, tiny satellites with miniaturized thrusters will significantly help change aerodynamics and launch processes. Whereas systemic payload structures can bear maximum weight, theoretically expanding the number of Nanosatellites deployed per launch. This paper attempts to facilitate various elements that make it practical in enabling a decision-making process related to technical aspects of the launch cost and future utilization of CubeSat technology.
2

Nascer em hospital amigo da criança no Rio de Janeiro: um fator de proteção ao aleitamento materno? / Is Being Born in Baby-Friendly Hospitals a Protective Factor for Breastfeeding?

Paula Florence Sampaio 31 March 2010 (has links)
Apesar de existirem evidências suficientes sobre benefícios do aleitamento materno (AM), apenas 35% das crianças são amamentadas exclusivamente até o quarto mês de vida. Visando estender esta prática, OMS/UNICEF lançaram a Iniciativa Hospital Amigo da Criança (IHAC), que estabelece sistema de credenciamento para maternidades de acordo com grau de incentivo ao AM. Esta dissertação pretende investigar a efetividade da IHAC na duração de dois tipos de aleitamento materno: exclusivo (AME) e predominante (AMP) entre crianças usuárias de Unidades Básicas de Saúde (UBS) do Rio de Janeiro. Trata-se de estudo transversal, sendo a população de estudo constituída de 811 mães de crianças menores de 5 meses de idade, selecionadas aleatoriamente em cinco UBS na cidade do Rio de Janeiro. A variável de exposição foi categorizada em local de nascimento ocorridos em HAC, naqueles em vias de receber titulação (EVHAC) e naqueles sem titulação. Os desfechos considerados foram duração do AME e do AMP, que inclui também crianças em AME (AMEP). Na análise dos dados, optou-se pelo modelo log-log complementar, que permitiu recompor experiência longitudinal da coorte através do recordatório alimentar de 7 dias e da informação da idade das mesmas, caracterizando abordagem tipo current status data. Mesmo após controle por variáveis sociodemográficas, relativas ao estilo de vida e aos aspectos psicossociais maternos, à utilização dos serviços de saúde, idade e saúde da criança, houve maior duração do AME e AMEP em crianças nascidas em HAC e EVHAC. As taxas de AME e de AMEP são mais de duas vezes maiores entre recém-nascidos que nasceram em HAC e EVHAC. Tal efeito diminui ao longo da idade da criança, mantendo-se evidente até quatro (EVHAC) e dois (HAC) meses de vida quando se considera AME e até dois (EVHAC) e cinco (HAC) meses quando se considera AMEP. Os resultados confirmam a efetividade da IHAC nesta clientela,especialmente na manutenção de AME e AMEP nos primeiros meses de vida. Estes também sugerem necessidade de fortalecimento da IHAC e maior integração entre maternidades e UBS, visando garantir aleitamento exclusivo até seis meses de vida / Although there are sufficient evidences about breastfeeding (BF) benefits, only 35% of infants worldwide are exclusively breastfed during the first four months of life. As an effort to extend BF duration, WHO/UNICEF launched the Baby-Friendly Hospital Initiative (BFHI), which establishes hospitals accreditation as Baby-Friendly Hospitals (BFH) when it meets the Ten Steps for Successful Breastfeeding. This dissertation aims to investigate the effectiveness of the BFHI on exclusive breastfeeding (EBF) and exclusive plus predominant breastfeeding (EPBF) duration. This is a cross-sectional study with collected information throughout interviews of 811 mothers of children under 5 months old, randomly selected at five health centers in Rio de Janeiro. Exposure variable was classified according to hospitals compliance with the Ten Steps. There were three possible status: accredited hospitals (BFH), working in becoming BFH or certified hospitals (CBFH) and hospitals without BFHI accreditation or certification. Outcomes were EBF and EPBF duration. Data was analyzed by complementary log-log transformation models, which allowed capture cohort longitudinal experience through 7-day feeding recordatory and infants age (current status data). Even after adjusting analysis for sociodemographic, life style and psychological maternal factors, health services use and babies age and state of health, there was longer duration of EBF and EPBF of infants born in BFH and CBFH. EBF and EPBF rates were twice higher in newborns born in BFH and CBFH. This protective effect on EBF and EPBF decreases along childs age and its noticed until four (CBFH) and two (BFH) months of age when EBF is considered and until two (CBFH) and five (EBF) months for EPBF. The finding indicates the effectiveness of BFHI in maintaining EBF and EPBF through the first months of life in this population. In order to extend BF duration until six months of life, as recommended by WHO, it would be necessary not only to strengthen the BFHI but also to develop and encourage more actions in favor of breastfeeding, focusing on primary health care facilities
3

Nascer em hospital amigo da criança no Rio de Janeiro: um fator de proteção ao aleitamento materno? / Is Being Born in Baby-Friendly Hospitals a Protective Factor for Breastfeeding?

Paula Florence Sampaio 31 March 2010 (has links)
Apesar de existirem evidências suficientes sobre benefícios do aleitamento materno (AM), apenas 35% das crianças são amamentadas exclusivamente até o quarto mês de vida. Visando estender esta prática, OMS/UNICEF lançaram a Iniciativa Hospital Amigo da Criança (IHAC), que estabelece sistema de credenciamento para maternidades de acordo com grau de incentivo ao AM. Esta dissertação pretende investigar a efetividade da IHAC na duração de dois tipos de aleitamento materno: exclusivo (AME) e predominante (AMP) entre crianças usuárias de Unidades Básicas de Saúde (UBS) do Rio de Janeiro. Trata-se de estudo transversal, sendo a população de estudo constituída de 811 mães de crianças menores de 5 meses de idade, selecionadas aleatoriamente em cinco UBS na cidade do Rio de Janeiro. A variável de exposição foi categorizada em local de nascimento ocorridos em HAC, naqueles em vias de receber titulação (EVHAC) e naqueles sem titulação. Os desfechos considerados foram duração do AME e do AMP, que inclui também crianças em AME (AMEP). Na análise dos dados, optou-se pelo modelo log-log complementar, que permitiu recompor experiência longitudinal da coorte através do recordatório alimentar de 7 dias e da informação da idade das mesmas, caracterizando abordagem tipo current status data. Mesmo após controle por variáveis sociodemográficas, relativas ao estilo de vida e aos aspectos psicossociais maternos, à utilização dos serviços de saúde, idade e saúde da criança, houve maior duração do AME e AMEP em crianças nascidas em HAC e EVHAC. As taxas de AME e de AMEP são mais de duas vezes maiores entre recém-nascidos que nasceram em HAC e EVHAC. Tal efeito diminui ao longo da idade da criança, mantendo-se evidente até quatro (EVHAC) e dois (HAC) meses de vida quando se considera AME e até dois (EVHAC) e cinco (HAC) meses quando se considera AMEP. Os resultados confirmam a efetividade da IHAC nesta clientela,especialmente na manutenção de AME e AMEP nos primeiros meses de vida. Estes também sugerem necessidade de fortalecimento da IHAC e maior integração entre maternidades e UBS, visando garantir aleitamento exclusivo até seis meses de vida / Although there are sufficient evidences about breastfeeding (BF) benefits, only 35% of infants worldwide are exclusively breastfed during the first four months of life. As an effort to extend BF duration, WHO/UNICEF launched the Baby-Friendly Hospital Initiative (BFHI), which establishes hospitals accreditation as Baby-Friendly Hospitals (BFH) when it meets the Ten Steps for Successful Breastfeeding. This dissertation aims to investigate the effectiveness of the BFHI on exclusive breastfeeding (EBF) and exclusive plus predominant breastfeeding (EPBF) duration. This is a cross-sectional study with collected information throughout interviews of 811 mothers of children under 5 months old, randomly selected at five health centers in Rio de Janeiro. Exposure variable was classified according to hospitals compliance with the Ten Steps. There were three possible status: accredited hospitals (BFH), working in becoming BFH or certified hospitals (CBFH) and hospitals without BFHI accreditation or certification. Outcomes were EBF and EPBF duration. Data was analyzed by complementary log-log transformation models, which allowed capture cohort longitudinal experience through 7-day feeding recordatory and infants age (current status data). Even after adjusting analysis for sociodemographic, life style and psychological maternal factors, health services use and babies age and state of health, there was longer duration of EBF and EPBF of infants born in BFH and CBFH. EBF and EPBF rates were twice higher in newborns born in BFH and CBFH. This protective effect on EBF and EPBF decreases along childs age and its noticed until four (CBFH) and two (BFH) months of age when EBF is considered and until two (CBFH) and five (EBF) months for EPBF. The finding indicates the effectiveness of BFHI in maintaining EBF and EPBF through the first months of life in this population. In order to extend BF duration until six months of life, as recommended by WHO, it would be necessary not only to strengthen the BFHI but also to develop and encourage more actions in favor of breastfeeding, focusing on primary health care facilities
4

Méthodes de comparaisons de deux ou plusieurs groupes de données censurées par intervalle. Avec application en immunologie clinique. / Methods of comparisons of two or more groups of interval censored data. With application in clinical immunology.

Jonas, Sarah Flora 03 October 2018 (has links)
Dans le cadre des analyses des données de survie, la comparaison de plusieurs groupes d’individus, où l'événement d'intérêt est censuré par intervalle, représente un défi méthodologique. Lorsque le suivi des patients au cours de l'étude n'est pas continu, l'événement d'intérêt pourra survenir entre deux dates d'observation; il est dit censuré par intervalle. Des tests de comparaisons des distributions des temps de survie pour plusieurs groupes, adaptés à la censure par intervalle, ont été développés (tests du score, tests de pseudo log-rank pondérés, tests des rangs). C’est dans ce contexte que nous avons proposé deux nouveaux tests de comparaisons de groupes adaptés à des situations particulières de censure par intervalle. Le premier test concerne une situation où l’hypothèse alternative considère que les fonctions de risque instantané se croisent. Le second test concerne une situation où la population étudiée comporte une fraction non à risque pour l’événement d’intérêt. Ces deux tests ont fait l'objet d'une application sur des données réelles d'immunologie clinique. / In the context of analysis of survival data, the comparison of several groups of individuals, where the event of interest is interval censored, represents a methodological challenge. When the monitoring of patients during the study is not continuous, the event of interest may occur between two observation dates; it is said "interval censored". Tests of comparisons of survival time distributions for several groups, adapted for interval censoring, have been developed (score tests, weighted pseudo log-rank tests, rank tests). In this context, we have developped two new group comparison tests adapted to the particular situations of interval censoring. The first test apply to a situation where the alternative hypothesis considers that the hazard functions cross. The second test concerns a situation where the study population has a fraction not at risk for the event of interest. Both of these tests have been applied to real clinical immunology dataset.
5

D- and Ds-optimal Designs for Estimation of Parameters in Bivariate Copula Models

Liu, Hua-Kun 27 July 2007 (has links)
For current status data, the failure time of interest may not be observed exactly. The type of this data consists only of a monitoring time and knowledge of whether the failure time occurred before or after the monitoring time. In order to be able to obtain more information from this data, so the monitoring time is very important. In this work, the optimal designs for determining the monitoring times such that maximum information may be obtained in bivariate copula model (Clayton) are investigated. Here, the D- optimal criterion is used to decide the best monitoring time Ci (i = 1; ¢ ¢ ¢ ; n), then use these monitoring times Ci to estimate the unknown parameters simultaneously by maximizing the corresponding likelihood function. Ds-optimal designs for estimation of association parameter in the copula model are also discussed. Simulation studies are presented to compare the performance of using monitoring time C¤D and C¤Ds to do the estimation.
6

C-optimal Designs for Parameter Testing with Survival Data under Bivariate Copula Models

Yeh, Chia-Min 31 July 2007 (has links)
Current status data are usually obtained with a failure time variable T which is diffcult observed but can be determined to lie below or above a random monitoring time or inspection time t. In this work we consider bivariate current status data ${t,delta_1,delta_2}$ and assume we have some prior information of the bivariate failure time variables T1 and T2. Our main goal is to find an optimal inspection time for testing the relationship between T1 and T2.
7

Robust Methods for Interval-Censored Life History Data

Tolusso, David January 2008 (has links)
Interval censoring arises frequently in life history data, as individuals are often only observed at a sequence of assessment times. This leads to a situation where we do not know when an event of interest occurs, only that it occurred somewhere between two assessment times. Here, the focus will be on methods of estimation for recurrent event data, current status data, and multistate data, subject to interval censoring. With recurrent event data, the focus is often on estimating the rate and mean functions. Nonparametric estimates are readily available, but are not smooth. Methods based on local likelihood and the assumption of a Poisson process are developed to obtain smooth estimates of the rate and mean functions without specifying a parametric form. Covariates and extra-Poisson variation are accommodated by using a pseudo-profile local likelihood. The methods are assessed by simulations and applied to a number of datasets, including data from a psoriatic arthritis clinic. Current status data is an extreme form of interval censoring that occurs when each individual is observed at only one assessment time. If current status data arise in clusters, this must be taken into account in order to obtain valid conclusions. Copulas offer a convenient framework for modelling the association separately from the margins. Estimating equations are developed for estimating marginal parameters as well as association parameters. Efficiency and robustness to the choice of copula are examined for first and second order estimating equations. The methods are applied to data from an orthopedic surgery study as well as data on joint damage in psoriatic arthritis. Multistate models can be used to characterize the progression of a disease as individuals move through different states. Considerable attention is given to a three-state model to characterize the development of a back condition known as spondylitis in psoriatic arthritis, along with the associated risk of mortality. Robust estimates of the state occupancy probabilities are derived based on a difference in distribution functions of the entry times. A five-state model which differentiates between left-side and right-side spondylitis is also considered, which allows us to characterize what effect spondylitis on one side of the body has on the development of spondylitis on the other side. Covariate effects are considered through multiplicative time homogeneous Markov models. The robust state occupancy probabilities are also applied to data on CMV infection in patients with HIV.
8

Robust Methods for Interval-Censored Life History Data

Tolusso, David January 2008 (has links)
Interval censoring arises frequently in life history data, as individuals are often only observed at a sequence of assessment times. This leads to a situation where we do not know when an event of interest occurs, only that it occurred somewhere between two assessment times. Here, the focus will be on methods of estimation for recurrent event data, current status data, and multistate data, subject to interval censoring. With recurrent event data, the focus is often on estimating the rate and mean functions. Nonparametric estimates are readily available, but are not smooth. Methods based on local likelihood and the assumption of a Poisson process are developed to obtain smooth estimates of the rate and mean functions without specifying a parametric form. Covariates and extra-Poisson variation are accommodated by using a pseudo-profile local likelihood. The methods are assessed by simulations and applied to a number of datasets, including data from a psoriatic arthritis clinic. Current status data is an extreme form of interval censoring that occurs when each individual is observed at only one assessment time. If current status data arise in clusters, this must be taken into account in order to obtain valid conclusions. Copulas offer a convenient framework for modelling the association separately from the margins. Estimating equations are developed for estimating marginal parameters as well as association parameters. Efficiency and robustness to the choice of copula are examined for first and second order estimating equations. The methods are applied to data from an orthopedic surgery study as well as data on joint damage in psoriatic arthritis. Multistate models can be used to characterize the progression of a disease as individuals move through different states. Considerable attention is given to a three-state model to characterize the development of a back condition known as spondylitis in psoriatic arthritis, along with the associated risk of mortality. Robust estimates of the state occupancy probabilities are derived based on a difference in distribution functions of the entry times. A five-state model which differentiates between left-side and right-side spondylitis is also considered, which allows us to characterize what effect spondylitis on one side of the body has on the development of spondylitis on the other side. Covariate effects are considered through multiplicative time homogeneous Markov models. The robust state occupancy probabilities are also applied to data on CMV infection in patients with HIV.
9

Perspektivy ekologického zemědělství v EU se zaměřením na ČR / Prospects of organic farming in the EU with a focus on the Czech Republic

Zikmund, Tomáš January 2012 (has links)
The stimulus for the development of organic farming in Europe came in 1924, but the important period for the development were 1970's. The beginning of organic farming in the Czech Republic can be considered as year 1988. Since the beginning of 1990's there has been considerable development of organic agriculture in all European countries. In 2010, there operated 218,500 farms across the European Union, while the total area of organically cultivated land covered 9,181,507 hectares, representing 5.10% of the total utilized area of agricultural land in the EU. Of this number, there were 3,515 farms in the Czech Republic, where the organically cultivated area reached 447,821 hectares. According to the action plan for organic farming in the Czech Republic the goal is to achieve 5,800 farms and 650,000 hectares of organic land in 2015. From the above it is clear that the aim of this thesis is to analyse recent developments, current status and prospects of organic farming in the European Union with an emphasis on the Czech Republic.
10

Rekonstrukce nosné ocelové konstrukce dvoupodlažního objektu / The Reconstruction of a Stell Structure two-storey Building.

Rapant, Jaromír January 2013 (has links)
his thesis deals with exploration of paper mill building, structural load, and assessment of current load bearing structure and proposing reconstruction. Bearing structure is entirely made out of steel and it’s done as XYZ frame. The building is located in Olsany u Sumperka, this defines the climate. The paper mill is of a platform of 54,0 x 48,25 m. It’s a two floor building with average height of 13,22m. Thesis contains foto documentation of the building and tests of strength of the steel in the bearing structure. Small statistical calculation was done, of all current elements of the steel structure. And necessary reconstruction was based on these calculations.

Page generated in 0.0688 seconds