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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.
21

Validade fatorial do Maslach Burnout Inventory-Human Services Survey (MBI-HSS) em uma amostra brasileira de auxiliares de enfermagem de um hospital universitário: influência da depressão / Factorial validity of the Maslach Burnout inventory - human services survey (MBI-HSS) among Brazilian nurse assistants of a university hospital: the influence of depression

Telma Ramos Trigo 18 February 2011 (has links)
A Síndrome de Burnout entre os profissionais da área da saúde vem sendo estudada em vários países e sua associação com transtornos depressivos tem sido relatada por vários estudos. Os resultados indicam validade para o burnout, diferenciando-o da depressão e por outro lado, associação dos índices de burnout e a sintomatologia depressiva. O Maslach Burnout Inventory-Human Service Survey (MBI-HSS) é o instrumento mais utilizado para avaliar o burnout. A estrutura de três fatores do MBI tem sido confirmada em várias amostras de diversos países. Entretanto, não encontramos estudos investigando a influência da depressão nas características psicométricas do MBI-HSS. Portanto, neste estudo, investigamos a validade do MBI-HSS em uma amostra de 521 auxiliares de enfermagem de um hospital universitário utilizando a análise fatorial exploratória, análise fatorial confirmatória e consistência interna pelo alfa de Cronbach. A amostra total foi dividida em um grupo com depressão maior e outro sem depressão maior. Tanto a amostra total, quanto as subamostras apresentaram elevados valores de alfa de Cronbach para a subescala de esgotamento emocional e valores intermediários para as subescalas de realização pessoal e de despersonalização. A análise do gráfico Scree plot, diferente da análise fatorial exploratória sem fixar os fatores, indicou a solução de três fatores, como na versão original da MBI-HSS. Fixando-se em três fatores, a análise fatorial exploratória revelou maior carga fatorial em Esgotamento Emocional (EE) de dois itens de Despersonalização (DE) na subamostra com depressão maior, mas não na subamostra sem depressão maior. Diferentemente, os itens 6 e 16 de EE apresentaram maior carga fatorial em DE na subamostra sem depressão mas não a amostra com depressão. Nossos resultados indicam que a presença de depressão maior pode influenciar as propriedades psicométricas da MBI-HSS. Sugerimos que pesquisadores considerem a avaliação da validade da MBI-HSS na amostra em questão anteriormente ao uso do MBI-HSS, incluindo a avaliação dos indivíduos com e sem depressão separadamente. / The burnout syndrome among health professionals has been studied in several countries and its association with depressive disorders have been reported by several studies. The results indicate validity for burnout, differentiating it from depression and on the other hand, association between burnout and depressive symptomatology. The Maslach Burnout Inventory-Human Service Survey (MBI-HSS) has been the most used instrument to evaluate burnout. The three-factor structure of the MBI has been confirmed in several samples from different countries. However, we did not find studies investigating the influence of depression on the psychometric characteristics of the MBI-HSS. Therefore, we investigated the validity of the MBI-HSS in a sample of 521 nursing assistants in a university hospital using exploratory factor analysis, confirmatory factor analysis and internal consistency (Cronbachs alpha coefficient). The total sample was divided into a group with major depression and one without major depression. Both the total sample and the subsamples showed high values of Cronbach\'s alpha for the subscale of emotional exhaustion and intermediate values for the subscales of personal accomplishment and depersonalization. The Scree plot analysis, unlike exploratory factor analysis without fixing the factors, indicated the three-factor solution, as in the original MBI-HSS. Settling into three factors, the exploratory factor analysis revealed the highest load factor in Emotional Exhaustion (EE) of two items in the subsample of Depersonalization (DE) with major depression but not in the subsample without major depression. In contrast, items 6 and 16 of EE had higher factor loading in DE in the subsample without depression but not in the sample with depression. Our results indicate that the presence of major depression may influence the psychometric properties of the MBI-HSS. We suggest that researchers consider the evaluation of the validity of the MBI-HSS in the sample prior to the use of the MBI-HSS, including assessment of individuals with and without depression separately
22

Structural, economic and material comparison of various steel grades under fatigue loading

Amobi, Ikechukwu Ugochukwu 28 March 2008 (has links)
ABSTRACT As industries are upgrading rapidly from a lower steel grade to higher ones it has become necessary to study the effect of changing from lower steel grades to higher grades. This thesis reports on fatigue life and behaviour, economic implications and material composition of these higher strength steels (HSS) as compared to the conventional grades. Three grades are commercially available in South Africa: 300W, 350W and 460W. These different steel grades (conventional and HSS) with the same moment capacities where subjected to constant dynamic stresses and the fatigue crack growth of the overloading and unloading were monitored and compared with each other. The influences of the overloading and unloading made standard grades perform better under repeated loading than the HSS, since HSS have been proved to have poor ductility, resulting in lower number of cycles to failure. An 85% increase in material cost was generated as HSS replaces the conventional lower steel grades. Reduction in number of cycles to failure in HSS was over 500%. A space analysis for a multi-storey building with 10 beam floors was conducted for the various steel grades using a software package. The buckling and linear behaviours of these structures were compared. Although the deflections were not too far apart, it was shown clearly that grade lower steel grades performed better than the higher grades. An optimization was conducted using the parameters discussed in the text or obtained from experiment and computer modelling, in order to aid in the selection criterion of general purpose steel. Grade 300W was the optimal grade although the result was based mainly on the cost and fatigue behaviour of the three grades.
23

Dohledový systém pro Internet Protocol Multimedia Subsystem / Surveillance system for Internet Protocol Multimedia Subsystem

Švec, Michal January 2013 (has links)
The master’s thesis describes IMS (IP Multimedia Subsystem) in terms of IMS core ele- ments (functional description, different implementation, signaling etc.) Communication protocols SIP and DIAMETER, together with SNMP protocol, which is used for collecting data are briefly described in this thesis.Thesis is also describing various IMS projects to- gether with Open IMS project, for whom was this surveillance system designed. Next part deals with architecture design of surveillance system along with management options implemented in surveillance system for users and administrators. The main part of master’s thesis deals with the description of the surveillance system for the experimental school Open IMS network and describes the remote configuration of core elements and monitoring of network traffic, together with the monitoring servers performance. The most of the data in the designed surveillance system are processed into graphs, which are regularly updated. The final part of master’s thesis describes the configuration and implementation of monitoring tools MRTG and NfSen that were used in created web based surveillance system.
24

Theoretical and experimental studies of a single tooth milling process

Werner, Mathias January 2012 (has links)
The industrial development of metal cutting processes in gear manufacturing aims at continuously increasing productivity, including increased tool reliability. Basically, the parameters that have an influence on the cutting processes should be known and possible to control. Gear manufacturing is highly important for the automotive industry. The prevalent manufacturing method is gear hobbing with hobs consisting of solid Powder Metallurgical High Speed Steel (PM HSS) with Physical Vapor Deposited (PVD) coatings. The hob teeth have to be reconditioned before wear reaches such levels that the gear quality becomes impaired. Such wear often results in a total breakdown of the tool. One crucial reason for this is that hobbing processes for the present often lack reliability; which makes it difficult for the gear manufacturers to predict the tool wear on the hob teeth and decide when the tool should be replaced in order to avoid severe damages. A consequence of catastrophic tool wear is that it leads to an instantaneously changed geometry of the cutting edge, which in turn implies that the machined gears do not comply with the stipulated properties on the machined gear products. A single tooth milling test (STMT) with tools of PM-HSS in a conventional milling machine has been developed in this research project, aiming at characterizing the effect of tool preparation on the type of wear mechanism. The experience and conclusions from these tests may probably be transferred to real PM-HSS hob tooling (HT). The advantages of such a test, compared to a real gear hob test, are primarily the cost reductions and time saving aspects with respect to both the design and the manufacturing of the cutting teeth The research presented in this thesis is based on experimental investigations and theoretical studies of significant parameters, i.e. the surface roughness and edge rounding, contributing to the robust and reliable design of a PM-HSS cutting tool. The research work has in addition to, the development of the milling test method, also comprised development of measuring methods and a simulation model based on the Finite Element Model (FEM). / <p>QC 20121105</p>
25

Innovative Modular High Performance Lightweight Decks for Accelerated Bridge Construction

Ghasemi, Sahar 13 November 2015 (has links)
At an average age of 42 years, 10% of the nation’s over 607,000 bridges are posted for load restrictions, with an additional 15% considered structurally deficient or functionally obsolete. While there are major concerns with decks in 75% of structurally deficient bridges, often weight and geometry of the deck further limit the load rating and functionality of the bridge. Traditional deck systems and construction methods usually lead to prolonged periods of traffic delays, limiting options for transportation agencies to replace or widen a bridge, especially in urban areas. The purpose of this study was to develop a new generation of ultra-lightweight super shallow solid deck systems to replace open grid steel decks on movable bridges and as well serve as a viable alternative in bridge deck replacements across the country. The study has led to a lightweight low-profile asymmetric waffle deck made with advanced materials. The asymmetry comes from the arrangement of primary and secondary ribs, respectively perpendicular and parallel to the direction of traffic. The waffle deck is made with ultrahigh performance concrete (UHPC) reinforced with either high-strength steel (HSS) or carbon fiber reinforced polymer (CFRP) reinforcement. With this combination, the deck weight was limited to below 21 psf and its overall depth to only 4 inch, while still meeting the strength and ductility demands for 4 ft. typical stringer spacing. It was further envisioned that the ultra-high strength of UHPC is best matched with the high strength of HSS or CFRP reinforcement for an efficient system and the ductile behavior of UHPC can help mask the linear elastic response of CFRP reinforcement and result in an overall ductile system. The issues of consideration from the design and constructability perspectives have included strength and stiffness, bond and development length for the reinforcement, punching shear and panel action. A series of experiments were conducted to help address these issues. Additionally full-size panels were made for testing under heavy vehicle simulator (HVS) at the accelerated pavement testing (APT) facility in Gainesville. Detailed finite element analyses were also carried out to help guide the design of this new generation of bridge decks. The research has confirmed the superior performance of the new deck system and its feasibility.
26

Optimalizace řezného procesu pro obrábění hliníkového profilu na CNC obráběcím centru / Optimalization of cutting process for machining of aluminium profile on CNC centre

Král, Ondřej January 2019 (has links)
This master‘s thesis deals with the suggestion of suitable tools for milling aluminum alloys profiles for the construction of aperture fillings and their aplication to a CNC machining center for increasing the efficiency of the cutting process. The first part of the thesis is focused on the description of the company and the workplace of production of aluminum alloys constructions. The following pages contain description of standardized products, which are used to identify the test profile that is part of the experimental verification. Next part of this thesis is characteristic of aluminum alloys and tool materials suitable for their machining. Second part of this work contains an analysis of the current state, suggestion of new cutting tools and their application to the production proces. At the end of this thesis there is the technical-economic evaluation that deals with the time and economic savings of the applied design.
27

Friction Stir Welding of High-Strength Automotive Steel

Olsen, Eric Michael 05 July 2007 (has links) (PDF)
The following thesis is a study on the ability to create acceptable welds in thin-plate, ultra-high-strength steels (UHSS) by way of friction stir welding (FSW). Steels are welded together to create tailor-welded blanks (TWB) for use in the automotive industry. Dual Phase (DP) 590, 780, and 980 steel as well as Transformation-Induced Plasticity (TRIP) 590 steel with thicknesses ranging from 1.2 mm to 1.8 mm were welded using friction stir welding under a variety of processing conditions, including experiments with dissimilar thicknesses. Samples were tested under tensile loads for initial determination if an acceptable weld had been created. Acceptable welds were created in both TRIP 590 and DP 590 at speeds up to 102 centimeters-per-minute. No acceptable welds were created in the DP 780 and DP 980 materials. A series of microhardness measurements were taken across weld samples to gain understanding as to the causes of failure. These data indicate that softening, caused by both excessive heat and insufficient heat can result in weld failure. Not enough heat causes the high concentration of martensite in these materials to temper while too much heat can cause excessive hardening in the weld, through the formation of even more martensite, which tends to promote failure mode during forming operations. Laser welding is one of the leading methods for creating tailor-welded blank. Therefore, laser welded samples of each material were tested and compared to Friction Stir Welded samples. Lower strength and elongation are measured in weld failure while the failure location itself determines the success of a weld. In short, an acceptable weld is one that breaks outside the weld nugget and Heat Affected Zone (HAZ) and where the tensile strength (both yield and ultimate) along with the elongation are comparable to the base material. In unacceptable welds, the sample broke in the weld nugget or HAZ while strength and elongations were well below those of the base material samples.
28

Studies of the PMWE : Polar Mesosphere Winter Echoes

Persson, Simon January 2022 (has links)
This Master thesis examines a phenomenon that occurs in the upper polar atmosphere, namely, Polar Mesospheric Winter Echoes, or PMWEs. PMWEs are radar echoes observed by Very High Frequency Mesosphere Stratosphere Troposphere (VHF MST) radar, from altitudes of 60 to 76 km at 7 to 15 UT, in the winter months from the middle of September to the beginning of May. The aforementioned specifications are the partial results of this thesis.PMWEs are generally understood to be caused by turbulence; however, radar data indicate some rare cases where PMWEs can be created with velocities exceeding the speed of sound, which is not possible with current turbulence theory. Kirkwood et al., 2006 and Belova, Kirkwood, and Sergienko, 2013 hypothesised that infrasound could generate the necessary conditions for PMWEs with velocities equal to or exceeding the speed of sound. Observations of PMWEs presented in this thesis have been carried out by the MST radar ESRAD, located at Esrange (67 56’N, 21 04’E) near Kiruna in northern Sweden. The radar operates at 52 MHz and has been performing continuous radar observations since Dec 1996. Observations of the infrasounds presented in this thesis were carried out by a microbarometer located close to Rymdcampus in Kiruna. Access to the data is restricted, but through university administration, this master’s thesis has been granted permission to use the data for the study of PMWEs. The instrument performed continuous infrasound measurements from the 24th of May 2016 and forward. This thesis will perform a full analysis of all radar data from the 17th of Dec 1996 until the 31st of Jan 2021 to assess the altitude interval, diurnal interval and yearly interval. The data given in the first section are a result of this work. Additionally, space weather parameters relation with the occurrence of PMWEs is analysed. Space weather parameters are very important for the chemistry and conditions present in the mesosphere. It is shown thatt here is a strong relation between solar wind and PMWE occurrence, decent relation with Kp index and no to weak relation with solar particle event (SPE). Correlating space weather and PMWEs in greater detail could be the subject of other studies. Last but most interesting, microbarometer data will be analysed for days where high-speed PMWEs are detected. Because of the rarity of these high-speed PMWEs, only seven total cases were found from 24 May 2016 onward, making the analysis of the infrasound measurements very limited, and no connection was found. However, it was found that days with high-speed PMWEs had an abnormally low amount of infrasound detections, further making analysis difficult but raising questions of why. This could mean that infrasound signals might be hindered from reaching the ground on days where we have high-speed PMWEs. No further conclusions can be made, as this indicates relation but not causation. Airborne infrasound instruments could be used to detect weaker infrasound signals due to being unaffected by wind disturbance at the ground.
29

Sambandet mellan andlighet och utbrändhet - en jämförande studie av beroendebehandlare i kriminal- och beroendevård

Hultén Sandeheim, Jonna January 2011 (has links)
Religiositet och andlighet tycks ha samband med fysisk och psykisk hälsa. I uppsatsen undersöks sambandet mellan andlighet och utbrändhet, två grupper behandlare jämförs och mätegenskaper hos skalorna Spirituality, Religiousness and Personal Beliefs Field-Test Instrument (WHOQOL-SRPB), Spiritual Involvement and Beliefs Scale (SIBS), Maslach Burnout Inventory – Human Service Survey (MBI-HSS) och Utbrändhet i arbetet (UA) undersöks. Studiedeltagarna var 38 programledare för kriminalvårdens tolvstegsprogram och 39 behandlare i ett psykoterapinätverk inom beroendevården (svarsfrekvens 61,5%). Andlighet korrelerade med personlig prestation (personal accomplishment; r = 0,315, p &lt; 0,05). I beroendevården fanns ett samband mellan hög grad av andlighet/religiositet och högre grad av utbrändhet. Studien visar att andlighet skulle kunna ge ökat självförtroende, och genom detta påverka hälsa och allmänt välbefinnande samt att effekten av andlighet/religiositet verkar vara positiv i andliga/religiösa sammanhang men inte i mer sekulariserade miljöer. Slutligen konstateras att validiteten hos utbrändhetsmåtten kan ifrågasättas och att vidare utveckling av andlighetsmåtten bör ske.
30

Development of a Lightweight Hurricane-Resistant Roof System

Amir Sayyafi, Ehssan 30 March 2017 (has links)
Roofs are the most vulnerable part of the building envelope that often get damaged when subjected to hurricane winds. Damage to the roofs has a devastating impact on the entire structure, including interior losses and service interruptions. This study aimed at the development of a novel light-weight composite flat roof system for industrial, commercial and multi-story residential buildings to withstand Category 5 hurricane wind effects based on the Florida Building Code requirements for hurricane-prone regions, the strictest wind design code in the United States. The proposed roof system is designed as a combination of two advanced materials: ultra-high performance concrete (UHPC), reinforced with high strength steel (HSS). The novel combination of these two materials in a specially designed cross section led to a lightweight low-profile ultra-thin-walled composite roof deck, with only 17 pounds per square foot self-weight, 4-inch overall depth and only ¾-inch thick flanges and webs, with no shear reinforcement or stirrup. Two groups of specimens, single-cell and multi-cell, were fabricated and tested in four-point flexure to determine the ultimate bending capacity and ductility of the system. Each group of specimens included two short-span (9 ft.) samples (due to the laboratory constraints) -- one specimen subjected to positive bending and the other one subjected to negative bending, representing the critical loading conditions including the effects of wind pressures. All specimens exhibited pure flexural failure in a ductile behavior and with no sign of shear failure. Finite element models of laboratory specimens were also developed and calibrated based on experimental data in order to project the performance of the system for larger and more realistic spans. The experimental work and the finite element analyses showed that the proposed roof system with its given section has adequate flexural and shear strength, and also meets serviceability requirements for a 20-foot long span. Moreover, connections for the roof system were proposed, including panel-to-panel connections and roof-to-wall connections. In addition to safety, the other advantages of the proposed roof system in comparison to the equivalent reinforced concrete roofs include a three-fold reduction in self-weight, a three-fold reduction in overall profile height, and a five-fold reduction of steel reinforcement. Together, these advantages may lead to an increased span length beyond what is typically feasible for the conventional reinforced concrete slabs. All these features translate the proposed deck to a sustainable roof system.

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