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  • 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.
31

Alternativas para aumento de capacidade de um terminal portuário de minério de ferro. / Alternatives to increase capacity of a iron ore port terminal.

Joyce Milanez Zampirolli 15 August 2016 (has links)
O crescimento da demanda por minério de ferro e a necessidade de melhoria nos terminais portuários, forçaram os portos a pensar e criar alternativas que refletissem em aumento de capacidade. Assim como os portos, as cidades ao redor dos terminais cresceram e avançaram sobre o território portuário, dificultando e até mesmo impedindo expansões físicas. Pensar e recriar conceitos que envolvam melhorias em todo o sistema produtivo é ter um olhar inovador para o processo e oferecer soluções que permitam aumento de capacidade, utilizando os recursos já existentes. No âmbito de se avaliar tais alternativas, foi utilizado um modelo de simulação de eventos discretos que possibilitou testar cenários de aumento de capacidade sem que para isso houvesse a necessidade de interferência na estrutura física, mas sim no tipo de produto movimentado e em mudanças nas atuais variáveis do sistema. / The iron ore demand and the need for improvement at the terminals forced the ports think and create alternatives that reflected in the incensement of capacity. In addiction with this growth, the cities around the terminals have grown and start to break into the port territory, making physical expansions hard to implement. To think and recreate concepts involving improvements throughout the production system is to have an innovative look at the process and offer solutions to increase capacity, using the existing resources. In the context of evaluating such alternatives, it was used a discrete events simulation model that enabled testing scenarios of capacity increase without interference in the physical structure, but in the quantity of different products types in the terminal and also changings in the system variables.
32

Tendências de temperatura e precipitação e cenários de mudanças climáticas de longo prazo no Nordeste do Brasil e em ilhas oceânicas

LACERDA, Francinete Francis 16 October 2015 (has links)
Submitted by Fabio Sobreira Campos da Costa (fabio.sobreira@ufpe.br) on 2016-07-15T12:33:37Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Tese__Francis Lacerda_21-03_16.pdf: 3871746 bytes, checksum: ad1b342ab1688e8eb924d0da7d968c22 (MD5) / Made available in DSpace on 2016-07-15T12:33:37Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Tese__Francis Lacerda_21-03_16.pdf: 3871746 bytes, checksum: ad1b342ab1688e8eb924d0da7d968c22 (MD5) Previous issue date: 2015-10-16 / No Nordeste do Brasil, e particularmente em Pernambuco, a precipitação e a temperatura estão entre as variáveis meteorológicas mais importantes para os estudos das mudanças climáticas, uma vez que sua variabilidade espacial e temporal são características marcantes do clima local. Os objetivos com este trabalho foram:determinar a presença de tendências de longo período da precipitação e da temperatura em Pernambuco, com a utilização de índices de detecção de mudanças climáticas, com base em dados observacionais de estações meteorológicas no continente e em ilhas oceânicas;realizar um estudo de balanço hídrico para o diagnóstico da disponibilidade hídrica e simulações numéricas com modelo atmosférico regional aninhado em cenário global de mudança climática, do modelo climático do Hadley Centre. Este trabalho contém o diagnóstico das alterações climáticas em localidades do estado de Pernambuco e em ilhas no Oceano Atlântico Tropical com dados de séries temporais diárias de temperatura e de precipitação com mais de 40 anos, com cenários futuros de mudanças do clima na região, para o período de 2010 a 2050. Os resultados indicaram tendências de aumento das temperaturas máximas e redução da pluviosidade média anual em todos os postos inspecionados. Em decorrência, constatou-se a tendência à aridificação em localidades do Sertão e do Agreste de Pernambuco. As análises dos dados climáticos em ilhas oceânicas mostraram um pequeno aquecimento em Fernando de Noronha e acentuada tendência de aquecimento e de aridificação em Cabo Verde, semelhantes às tendências de longo prazo detectadas em Araripina, no semiárido de Pernambuco. As tendências de temperatura e precipitação, observadas, são indicativas de que ocorrem processos de aridificação em Pernambuco e Cabo Verde. Os resultados do balanço hídrico e suas projeções indicaram uma diminuição da disponibilidade de água no solo e precipitação total e aumento das taxas de evapotranspiração potencial, em praticamente todas as áreas, ao longo dos anos. As simulações atmosféricas foram consistentes com os dados das estações em relação ao presente aquecimento; os cenários de mudanças climáticas para 2010-2050 indicaram um aumento mais rápido da temperatura máxima diária no Nordeste se comparada às simulações para o passado recente. / In Northeast Brazil, and particularly in Pernambuco, precipitation and temperature are among the most important meteorological variables for studies of climate change, since their spatial and temporal variability characterize the local climate. The aimswith this study were to determine the presence of long-term precipitation and temperature trends in Pernambuco, with the use of climate change detection rates, based on observational data from weather stations on the continent and on oceanic islands and to conduct a water balance study for the diagnosis of water availability and numerical simulations with regional atmospheric model nested in the global scenario of climate change, the Hadley Centre climate model. This work contains the diagnosis of climate change in the State of Pernambuco locations and in the Atlantic Ocean Tropical islands with data daily time temperature series and precipitation over 40 years with future scenarios of climate change in the region, for the period of 2010 to 2050. The results showed increasing trends of maximum temperatures and reduced average annual rainfall at all stations inspected. Also, a tendency to aridificação in the Sertãoand in the Agreste of Pernambuco was detected. The analysis of climate data on oceanic islands showed a small heating in Fernando de Noronha and a marked warming trend and aridificação in Cape Verde, similar to long-term trends detected in Araripina, in the semiarid region of Pernambuco. Trends in temperature and precipitation observed are indicative that aridificação processes in Pernambuco and Cape Verde are on the way. The results of the water balance and its projections indicated a decrease in water availability in the soil and total precipitation and increased evapotranspiration rates, in almost all areas over the years. The weather simulations were consistent with the data of the stations in relation to this warming rate; the climate change scenarios for 2010-2050 indicated a faster increase in the maximum daily temperatures in the Northeast compared to simulations of the recent past.
33

Analysis of crosstalk signals in a cylindrical layered volume conductor – Influence of the anatomy, detection system and physical properties of the tissues

Viljoen, Suretha 08 August 2005 (has links)
A comparison of the ability of different spatial filters to reduce the amount of crosstalk in a surface electromyography (sEMG) measurement was conducted. It focused on the influence of different properties of the muscle anatomy and detection system used on the amount of crosstalk present in the measurements. An analytical model was developed which enabled the simulation of single fibre action potentials (SFAPs). These fibres were grouped together in motor units (MUs). Each MU has characteristics which, along with the SFAPs, are used to obtain the motor unit action potential (MUAP). A summation of the MUAPs from all the MUs in a muscle leads to the electromyogram (EMG) signal generated by the muscle. This is the first model which simulates a complete muscle for crosstalk investigation. Previous studies were done for single fibres (Farina&Rainoldi 1999; Farina et al. 2002e; Farina et al. 2004a) or MUs (Dimitrova et al. 2002; Dimitrov et al. 2003; Winter et al. 1994). Lowery et al. simulated a complete muscle, but only investigated one spatial filter (Lowery et al. 2003a). This model is thus the first of its kind. EMG signals were generated for limbs with different anatomical properties and recorded with various detection systems. The parameters used for comparison of the recorded signals are the average rectified value (ARV) and mean frequency (MNF), which describe the amplitude and frequency components of an EMG signal, respectively. These parameters were computed for each EMG signal and interpreted to make recommendations on which detection system results in the best crosstalk rejection for a specific experimental set-up. The conclusion is that crosstalk selectivity in an sEMG measurement is decreased by increasing the thickness of the fat layer, increasing the skin conductivity, decreasing the fibre length, increasing the interelectrode distance of the detection system, placing the detection electrodes directly above the end-plate area or an increased state of muscle contraction. Varying the contraction force strength or placing the detection electrodes directly above the tendon area has no influence on the crosstalk selectivity. For most of the conditions investigated, the normal double differential (NDD) detection system results in the best crosstalk reduction. The only exceptions are a set-up with poor skin conductivity where NDD and double differential (DD) performed comparably, and the two simulations in which the muscle length is varied, where the DD filter performed best. Previous studies have found DD to be more selective for crosstalk rejection than NDD (Dimitrov et al. 2003; Farina et al. 2002a; Van Vlugt&Van Dijk 2000). Possible reasons for the contradictory results are the high value of skin conductivity currently used or influences of the muscle geometry. / Dissertation (MEng(Bio-Engineering))--University of Pretoria, 2007. / Electrical, Electronic and Computer Engineering / unrestricted
34

Návrh na zefektivnění procesu obrábění válcové součásti pro ropné vrty / Efficiency Improvement Proposal of Machining Process of Cylinder Component for Oil Wells

Koudela, Michal January 2015 (has links)
This diploma thesis is concerned with a proposal for increasing the efficiency of machining when manufacturing an inner sleeve at the company Sanborn a.s. In the diploma thesis, the technology used for machining itself is first briefly described, followed by a description of the original production technology including a description of machine and hand tools used and cutting conditions. The next part of the paper describes the proposal for increasing the efficiency of machining operations. The proposal includes a description of the suggested solution that will lead to increased efficiency, a machine proposed for the specific operation, appropriate tools and proposed cutting conditions. The benefits of implementing the proposal are also described here, both in terms of saving unit time, and in terms of the machining technology itself, where, for example, the formation of chips is improved, the inner tension of machined components reduced, etc. The diploma thesis further includes a technical-economic evaluation assessing the economic benefits of the changes introduced.
35

Návrh výroby jednoúčelového stupňovitého obráběcího nástroje / Production Concept of Single-purpose Stepped Cutting Tool

Opršál, Ladislav January 2016 (has links)
The aim of this thesis is to propose a single-purpose stepped cutting tool for the drilling of the cylinder head. The thesis first introduces the current production of the cylinder head, including the description of the cutting conditions and the machines and tools used in the production process. The second part of the thesis is focused on the drilling of a three-step hole for which a step drill bit is proposed. The proposal describes the development of the drill bit, heat treatment, the method of clamping, the replaceable cutting tips used in the production process, additions for further machining and the cutting conditions. The last part of the thesis then deals with the technical-economic analysis, comparing the present and innovated stage of the production of the cylinder head.
36

Konflikten mellan bevarandekrav och tilläggsisolering : The conflict between conservation requirements and additional insulation

Wickström, Maria, Zahharov, Taimi January 2013 (has links)
Sweden has formulated ambitious energy goals which signify that by year 2050 the energy usage should be halved. One of the objectives is the reduction of energy usage by 20% by year 2020 and that it should be compared to the usage of energy from 1995. In parallel with increased energy requirements for buildings the demand on housing conservation, by highlighting also buildings from the last 50 years as part of the building heritage, continues to enhance, which in theory means that there is a conflict between these. The law will never be able to point out unique buildings and PBL (planning and building act) is not especially concrete. The National Housing Board has tried to make this more concrete by the new BBR regulations though there are still an enormous variety of interpretations. This report deals with the conflict between conservation requirements and additional insulation of the building envelope and is limited to multi-residential buildings built between the years 1945 and 1975. It is the stock with the greatest energy consumption and that is where the big challenge lies. The question is whether in practice it is no conflict between conservation requirements and additional insulation of the building envelope and what it in this case depends. With the support of background facts, interview questions were formulated for different participants. By interviews with property-owners, municipalities and other partners it has been shown that the creation of zoning determines whether a property has been preserved. In municipalities with a metropolitan character the interest in conservation issues are the greatest and Stockholm municipality distinguishes itself, providing significant space in regards to this subject. The smaller municipalities do not believe in that the preservation of our multi-residential buildings are central but that there lies a greater problem in areal density and that eventually great portions of the genuine country will disappear. Only in isolated cases, conservation requirements became an obstacle in performing façade renovations. Property owners are interested in the conservation issue; however, it must be weighed against the economic condition and therefore is it in sight of what is a good conservation. / Sverige har formulerat ambitiösa energimål som innebär att till år 2050 ska energianvändningen halveras, där ett delmål är minskning med 20 % till år 2020 och det ska jämföras med energianvändningen från år 1995. Parallellt med ökade energikrav för byggnader ställs det även allt högre krav på husens bevarande, vilket teoretiskt innebär att det ligger en konflikt mellan dessa. Lagen kommer aldrig att kunna peka ut unika byggnader och PBL (plan- och bygglagen) är inte särskilt konkret. Nu har Boverket försökt konkretisera genom nya BBR reglerna, men det finns ändå oerhört mycket plats för tolkningar. Denna rapport behandlar konflikten mellan bevarandekrav och tilläggsisolering av klimatskalet och är begränsad till flerbostadshus byggda mellan åren 1945 och 1975. Det är det bestånd som har störst energiåtgång och det är där den stora utmaningen ligger. Frågan är om det i praktiken ligger någon konflikt mellan bevarandekrav och tilläggsisolering av klimatskalet och vad den i så fall beror på? Med stöd av bakgrundsfakta har intervjufrågor formulerats till olika aktörer. I intervjuer med fastighetsägare, kommuner och övriga parter har det visat sig att utformningen av detaljplanen är avgörande för om en fastighet kan bevaras. I kommuner med storstadskaraktär är intresset för bevarandefrågorna störst och Stockholms kommun utmärker sig, där dessa frågor getts störst utrymme. De mindre kommunerna anser inte att bevarandet av våra flerbostadshus är centralt utan där är det ett större problem att områdena förtätas och att på sikt stora delar av den genuina landsbygden kommer att försvinna. Endast i enstaka fall har bevarandekraven blivit ett hinder för att utföra fasadrenoveringar. Fastighetsägare är intresserade för bevarande frågan men detta måste vägas mot ekonomiska förutsättningar och därför skiljer det i synen om vad som är ett gott bevarande
37

The effect of increased axle loading on saturated and unsaturated railway foundation materials

Mpye, Godisang David January 2020 (has links)
The aim of the research is to investigate the effect of increased axle loading on saturated and unsaturated railway foundation materials for heavy haul applications. The research methodology comprises of a literature review to identify the lacuna in the scientific knowledge, finite element modelling for characterisation of railway cyclic loading, development of a cyclic triaxial apparatus for laboratory testing and experimental work, followed by analysis, interpretation and discussion of results and lastly the formulation of conclusions and recommendations. The axle loading of interest start with a base load of 20 tonnes per axle for general freight followed by increased axle loading of 26, 30, 32.5 and 40 tonnes per axle for heavy haul. The test materials used in the experimental work are representative of the subballast and subgrade layers in a railway substructure. As a reproduction of the climatic conditions in the field and the loading from passing trains, experimental testing was carried out on saturated samples under undrained conditions and unsaturated samples under constant water content. Unsaturated samples were prepared to matric suctions of 50, 100 and 225 kPa via axis translation. Monotonic and cyclic tests were conducted to investigate the behaviour of railway foundation materials. Critical state theory for saturated and unsaturated soils is used as a method of analysis in establishing the failure criterion and the failure envelope. Various parameters, such as stress states, strains, resilient modulus, pore water pressure and matric suction are also utilised in investigating trends and behaviours. Based on the monotonic test results, the shear strength of unsaturated samples was found to be greater than that of saturated samples, attributed mainly to strain hardening caused by the unsaturated soil conditions, with the presence of a peak deviator stress when plotted on the stress-strain graph. However, unsaturated samples were also found to be prone to load-collapse during monotonic shear, even when the water content and confining stress remained constant, which resulted in brittle behaviour with the sudden rupture and formation of multiple bifurcation shear bands and slip planes. Based on the cyclic tests on saturated materials, it was discovered that increased axle loading can result in phase-transition in soil behaviour, based on the stress states in the soil relative to the critical state line plotted in the effective stress space. Stress states below the critical state line resulted in a no-phase transition with dilation behaviour. Stress states on the critical state line resulted in a single-phase transition from dilation to contraction. Stress states above the critical state line resulted in a double-phase transition from dilation to contraction behaviour and then strain-softening. It is therefore concluded that increased axle loading can only be sustained by materials which presented dilation and no phase-transition in soil behaviour, which occurred at axle loading of 20 and 26 tonnes per axle for the subballast and subgrade materials. Based on the cyclic tests on unsaturated materials, it was established that increased axle loading did not cause material failure for all load axle cases and materials. The stress states of all tests plotted well below the failure envelope in the net stress space, which is indicative of resilient and elastic behaviour. Increased axle loading instead resulted in decreased permanent strain, until the critical level of repeated deviator stress of 32.5 tonnes per axle was found, where the permanent strain increased. It is therefore concluded that, as a result of the increased shear strength from the strain hardening property of unsaturated materials, an increased axle loading of 32.5 tonnes per axle can be safely sustained by the tested materials provided the matric suction in the soil is greater than 50 kPa. / Thesis (PhD)--University of Pretoria, 2020. / Civil Engineering / PhD / Unrestricted
38

Perfecting Patient Bed Flow in the Emergency Department

Moreira, Kim-Sun 01 January 2017 (has links)
Emergency department (ED) crowding is a serious problem in the United States. Crowding in the ED can result in delays that may negatively affect patient outcomes and increase the cost of care. The purpose of this project was to understand strategies that can help to improve patient flow in the ED. The plan-to-do-study act model for process improvement influenced this project. Secondary data were collected for a 2-month period to determine the impact of workflow processes (patient boarding time in ED, surge capacity and workflow processes including the impact of ancillary departments) on the movement of admitted patients from the ED to the inpatient units. Descriptive statistics were used to provide numerical summaries, frequencies, and percentages for the identified variables. The findings were consistent with an increased length of stay and longer ED boarding of patients due to the workflow process. Resulting recommendations included standardized calls for report on admitted patients within 30 minutes, timely discharge of patients, collaboration with attending physicians to facilitate evaluation of patients and orders, modification of staffing roles to ensure adequate staff, and identification of staff transporters to ensure timely transport of patients to their rooms. The findings helped to inform the development of a Bed Utilization Policy. The policy has been shared with the organization with the recommendation to implement and further evaluate to help manage bed flow. Development of utilization strategies that contribute to facilitating throughput will promote positive social change by providing nurses with the tools to help prepare for and respond to unexpected increases in patient volume. Improving efficiency with flow can help to improve patient care, timeliness, and safety.
39

Cellular Immunity in Children with Down Syndrome (Trisomy-21)

Noble, Roger Lee 01 May 1985 (has links)
Individuals with Down syndrome (US) suffer from increased incidence of respiratory infections and lymphoblastic leukemia, and a death rate that is particularly high in the first 5 years of life. Relatively few studies have probed immune parameters in young US children. Primary immune defects in DS may be masked by a degree of immune maturity in adults, and hygienic factors may have an effect on immune capability throughout the years. A study of young children can give clearer evidence of the actual primary immune defects in DS. Blood samples were drawn from 20 DS children under 6 years old and from age-matched controls. Packed blood cell volume was measured, various blood cell subpopulations were enumerated and differential counts were performed. Several tests of cellular immune function were performed and plasma zinc levels were determined using atomic adsorption spectrophotometry. Elevated hematocrit levels were observed in the US group. White blood cell counts and proportions of rosette-forming cells were normal in blood from DS children. Altered neutrophil and lymphocyte proportions in DS samples resulted from a depressed number of circulating lymphocytes in the these subjects. This indicated that T cell numbers are low in DS. DS individuals had a low number of circulating OKT4+ T cells which resulted in significantly depressed T4:T8 ratios. Cells from DS subjects exhibited a reduced proliferative response to phytohemagglutinin; a low response to the optimal concentration of concanavalin A was seen with DS samples, but at suboptimal doses the response was normal; suboptimal concentrations of pokeweed mitogen elicited normal responses by cells from DS children. Preliminary results suggest that interleukin-2 (IL-2) production in young children may correlate positively with age and that DS subjects may produce normal or elevated amounts of IL-2. This suggests that IL-2 receptor function may be defective in T cells from DS children. DS children had normal natural killer cell activity and cells from those children were no more sensitive to the augmenting effects of interferon-alpha than cells from control children. Plasma zinc levels in DS appeared to be normal. These findings not only provide evidence that the primary immune defect in DS involves low levels of T cells, but they show depressed number and function of helper T cells and suggest defective IL-2 receptor expression in DS.
40

The effect of · iron supplementation on maximal oxygen consumption in boys aged 9 11 years with iron deficiency and anaemia

Leach, Lloyd Llewellyn January 1993 (has links)
Magister Artium (Human Ecology) - MA(HE) / Iron deficiency anaemia is the most common abnormality of the blood in childhood (Karabus 1987). If the quantity of iron lost by the body exceeds iron intake, the body will draw on its iron reserves to counterbalance this deficit. However, the continuance of an iron imbalance will eventually lead to a reduction in body iron stores. Because iron forms an integral component of the oxygen transport mechanism of the body, it is understandable that the functional capacity of this system will be compromised under conditions of iron deficiency. A deficit in oxygen transport capacity will presumably indicate a decreased capacity to persevere in the face of continuing strenuous physical activity. The decrement in physical aerobic working capacity (maximal oxygen consumption) will largely be indicative of the decrease in oxygen transport capacity. Routine haemoglobin determinations carried out in the outpatient department of the Red Cross War Memorial Children's Hospital in Cape Town showed that many Coloured and African pre-schoolgoing children had abnormally low haemoglobin levels which occurred as a manifestation of iron deficiency anaemia (Lanzkowsky 1961). In another similar but more recent study also in the Cape Peninsula, Lamparelli et al. (1988) showed that the prevalence of iron deficiency anaemia in Coloured and African children was 15.5 % and 36.0 %, respectively . In this study, the condition of iron deficiency anaemia was particularly pronounced in urban Coloured children. In both these studies done in the Western Cape, the majority of Coloured children were classified as coming from the lowest socioeconomic income group in the community. In the majority of studies concerning the relationship between socioeconomic status and iron deficiency anaemia, it is often stated that low socioeconomic circumstances are significantly correlated to low blood haemoglobin levels (Expert Scientific Working Group 1985; Lanzkowsky 1959; Lanzkowsky 1961; World Health Organization 1972; World Health Organization 1975).

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