• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 155
  • 28
  • 21
  • 20
  • 16
  • 14
  • 13
  • 8
  • 6
  • 5
  • 5
  • 3
  • 2
  • 2
  • 1
  • Tagged with
  • 332
  • 88
  • 36
  • 35
  • 35
  • 34
  • 32
  • 31
  • 29
  • 28
  • 27
  • 26
  • 23
  • 22
  • 20
  • 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.
81

Advanced Numerical Techniques for Dynamic and Aerodynamic Analysis of Bridges

Naderian, Hamidreza January 2017 (has links)
To meet the economic, social and infrastructure needs of the community for safe and efficient transportation systems, long span bridges have been built throughout the world. Long span bridges are one of the most challenging kinds of structures in civil engineering. The cable-stayed bridges are of great interest mainly as an alternative and a more economic solution than the one of suspension bridges. In addition, the fiber reinforced polymer (FRP) composites are, nowadays, successfully used for constructing modern bridges, where the significant weight saving provides additional benefits. Because of the great flexibility, modern long-span cable-stayed bridges are usually very susceptible to dynamic loads especially to the earthquake and strong winds. Therefore, the earthquake-resistant and wind-resistant designs become one of key issues for successful construction of bridges. The objective of the present research is to develop a very efficient spline finite strip technique, for modelling and analysis of both conventional and hybrid FRP cable-stayed bridges. The study falls into the categories of bending, free vibration, seismic, and aerodynamic flutter analysis. The spline finite strip method (SFSM) is one of the most efficient numerical methods for structural analysis of bridges, reducing the time required for estimating the structural response without affecting the degree of accuracy. In the finite strip method, the degrees of freedom could be significantly reduced due to the semi-analytical nature of this method. However, the previous versions of SFSM are not able to model the entire bridge system. For that reason, the structural interactions between different structural components of the bridge could not be handled. In addition, the vibrations and displacements of the towers and cables could not be investigated. In the present formulation, all these obstacles have been eliminated. Moreover, the proposed finite strip technique is very efficient and accurate due to the drastic reduction in the formulation time, simplicity of data preparation, rapid rate convergence of the results, and the semi-analytical nature. Last but not least, and for the first time, a fully finite strip solution is extended to the area of wind engineering. Using the spline finite strip discretization, the aerodynamic stiffness and mass properties of the long-span cable-stayed bridge are derived. The aerodynamic properties along with the structural properties of long-span plates and bridges are formulated in the aerodynamic equation of motion and are used to analyze the flutter problem. The accuracy and efficiency of the proposed advanced finite strip method is verified against the finite element and field measurement results. The results demonstrate that this methodology and the associated computer code can accurately predict the dynamic and aerodynamic responses of the conventional and FRP long-span cable-stayed bridge systems. The outcome of the present research will lead to a comprehensive structural analysis of bridges in the framework of the proposed discretization which is more efficient and straightforward than the finite element analysis.
82

Evaluation of Compression Testing and Compression Failure Modes of Paperboard : Video analysis of paperboard during short-span compression and the suitability of short- and long-span compression testing of paperboard / Utvärdering av kompressionsbrottmoder och kompressionstestning för kartong : Videoanalys av kartong under kompressionstestning och lämpligheten av två olika kompressionsmetoder

Sjöstrand, Björn January 2013 (has links)
The objectives of the thesis were to find the mechanisms that govern compression failures in paperboard and to find the link between manufacturing process and paperboard properties. The thesis also investigates two different test methods and evaluates how suitable they are for paperboard grades. The materials are several commercial board grades and a set of hand-formed dynamic sheets that are made to mimic the construction of commercial paperboard. The method consists of mounting a stereomicroscope on a short-span compression tester and recording the compression failure on video, long-span compression testing and standard properties testing. The observed failure modes of paperboard under compression were classified into four categories depending on the appearance of the failures. Initiation of failure takes place where the structure is weakest and fiber buckling happens after the initiation, which consists of breaking of fiber-fiber bonds or fiber wall delamination. The compression strength is correlated to density and operations and raw materials that increase the density also increases the compression strength. Short-span compression and Long-span compression are not suitable for testing all kinds of papers; the clamps in short-span give bulky specimens an initial geometrical shape that can affect the given value of compression strength. Long-span compression is only suitable for a limited range of papers, one problem with too thin papers are low wavelength buckling.
83

En parametrisk undersökning om hur spännvidd och val av stomsystem påverkar materialkostnaderna för stallbyggnader

Hedlund, Per, Jakobsson, Anton January 2016 (has links)
Utvecklingen för Sveriges jordbruk går mot färre och större gårdar runt om i landet. Jordbrukarnas växande verksamhet resulterar i ett ökat antal djur i boskapen. Detta ger ett större behov av stallbyggnader med öppna ytor och långa spännvidder. Länsstyrelsen har uppmärksammat stora variationer i de totala byggkostnaderna för stallbyggnader i landet. Tillsammans med Länsstyrelsen Gävleborg utvecklades en idé att undersöka hur materialkostnaderna påverkas av olika spännvidder och olika stomsystem. Målsättningen är att undersökningen ska resultera i ett beslutsunderlag för ny-, till- och ombyggnation av stallbyggnader. Tidigare forskning och teori undersöktes samt ett flertal platsbesök gjordes för att öka kunskaperna inom området och fastställa vilka spännvidder och stomsystem som skulle undersökas. En parametrisk studie på fyra olika typfall av stallbyggnader gjordes. Två typfall i undersökningen konstruerades av trä och två av stål. Den parametriska studien ska redovisa samband mellan stallbyggnaders spännvidd och kostnad samt vilket stomsystem som är mest ekonomiskt fördelaktigt. Kostnaderna i undersökningen innefattar enbart materialkostnader. Resultatet visar att kostnaderna ökar linjärt med den ökande spännvidden. De undersökta typfallens materialkostnader är relativt likvärdiga, men treledsramen i stål har den lägsta materialkostnaden för samtliga undersökta spännvidder. / The Swedish agriculture is developing towards fewer and larger farms. The growing business for the farmers results in an increased number of animals in livestock. This provides a greater need for agricultural buildings with open spaces and long spans. Länsstyrelsen has noted large variations in total construction costs for agricultural buildings in the country. Along with Länsstyrelsen Gävleborg developed an idea to explore how material costs are affected by various spans and different frame systems. The objective is that the study will result in a decision-making basis for new construction and reconstruction of agricultural buildings. Previous research and theories were examined and a number of site visits were made to increase knowledge in the field and determine which spans and frame system to be investigated. Parametric studies of four different scenarios of the agricultural buildings were made. Two cases in the study were constructed of glulam and two of steel. The parametric study is to report relationship between agricultural building spans and costs as well as which building system that is most economically advantageous. The cost of the survey includes only material costs. The result shows that the cost increases linearly with the increasing span. The material costs of the four tested scenarios are relatively equal, but the tapered steel frame has the lowest material cost for all tested spans.
84

Representing sounds and spellings : Phonological decline and compensatory working memory in acquired hearing impairment / Representationer av ljud och stavning : Försämrad fonologisk förmåga och kompensatoriskt arbetsminne vid förvärvad hörselnedsättning

Classon, Elisabet January 2013 (has links)
This thesis examined phonological processing in adults with postlingually acquired moderate-to-severe hearing impairment (HI) and whether explicit working memory processing of phonology and individual working memory capacity (WMC) can compensate for degraded phonological representations in this group (papers I-III). A second aim was to provide reference data for a test of WMC, the reading span test, and to examine the relation between reading span test performance and speech recognition in noise in a larger sample of 50-89 year olds with HI (paper IV). Non-auditory tasks of phonological processing, episodic long-term memory and WMC were used in papers I-III, and both behavioral and electrophysiological measures were collected. Results showed that phonological processing was impaired in the group with HI but that WMC and explicit working memory processing of phonology could be employed to compensate for degraded phonological representations. However, this compensation may come at the cost of interfering with episodic memory encoding. An  electrophysiological marker of HI in text-based rhyme judgments was found. Paper IV presented reference data for reading span test performance in two versions of the test in individuals with HI, and results suggesting that WMC may be differentially predictive of speech recognition in noise in different age groups of older adults with HI. The clinical implications of the present results concerns the double disadvantage of individuals with lower WMC and HI. A structured assessment of WMC in rehabilitative settings would help to identify these individuals and tailor treatment to their needs. The reading span test is suggested as a suitable future candidate for clinical WMC assessment. / I denna avhandling undersöktes fonologiska processer hos personer med postlingualt förvärvad, måttlig till mycket grav hörselnedsättning (HNS) och om inkoppling av explicit bearbetning av fonologi eller individuell arbetsminneskapacitet kan kompensera för försämrade ljudminnen i denna grupp (studie I-III). Ett andra syfte var att sammanställa referensdata för ett test av arbetsminneskapacitet, lässpann, och undersöka relationen mellan prestation på lässpann ochigenkänning av tal-i-brus i en större grupp av 50-89 åriga personer  med HNS (studie IV). Icke-auditiva test av fonologisk förmåga, episodiskt långtidsminne och arbetsminneskapacitet användes i studie I-III och både beteendedata och elektrofysiologiska data samlades in. Resultaten visade på försämrad fonologisk förmåga i gruppen med HNS men också att explicit bearbetning av fonologi och arbetsminneskapacitet kunde användas för att kompensera för försämrade fonologiska representationer i denna grupp. Denna kompensation kan dock ske på bekostnad av att inkodning i episodiska långtidsminnet störs. Vidare identifierades en elektrofysiologisk markör för HNS i en textbaserad rimuppgift. I studie IV presenterades referensdata i två versioner av lässpanntestet för personer med mild till mycket grav HN och resultat som pekar mot möjliga skillnader mellan olika åldersgrupper i hur väl arbetsminneskapacitet predicerar igenkänning av tal-i-brus. Kliniska implikationer rör den dubbla belastning det innebär att ha både en HN och relativt sänkt arbetsminneskapacitet. En strukturerad bedömning av arbetsminneskapacitet i samband med rehabilitering skulle kunna bidra till att synliggöra dessa personer och anpassa insatser efter deras behov. Lässpanntestet är ett test som i framtiden skulle kunna vara användbart i det sammanhanget.
85

Life Histories of Women in Coaching

McCharles, Beth Lynne 21 April 2010 (has links)
The Canadian sport system is challenged by the lack of representation of female leaders and coaches. This is, in spite of statistics showing that female athletes account for almost half of all participants in sport, a number that is still growing (Sport Canada, 1999). Women have acquired equity in many areas of life and are accepted in leadership roles, however in the area of sport, women have yet to gain the full credibility and professional respect equal to their male counterparts. Previous research indicates that women who pursue a career in coaching face many adversities and struggle to attain a level of leadership where they can achieve their highest potential (Acosta & Carpenter, 2002). The purpose of this research is to gain an understanding of the lived experiences of elite female coaches, using Erikson’s (1950) theory of psychosocial development. In this study, the qualitative method of life history was used to learn about the experiences of female coaches, specifically the process of becoming and being elite coaches. Five elite Canadian coaches were interviewed. The major themes that developed through the analysis of the interviews were: (a) Support, (b) Overcoming Obstacles, (c) Personal Qualities and (d) The Bigger Picture. The study noted the importance of various support systems through one’s lifespan and some of the challenges a female athlete and coach must overcome to become a successful athlete, coach and mother. The study shares insight into the five women’s personal qualities that helped them grow into elite coaches. Finally, the participants described the process by which they came to find a leadership style with which they were comfortable, as coaches and as women.
86

The Effects of the Type A Behavior Pattern and Aerobic Exercise on the Allocation of Attention

Morton, Anne Aldredge 12 1900 (has links)
This investigation examined the effects of aerobic fitness and the Type A behavior pattern on cognitive functioning in the split-attention (dual task) paradigm. Sixty-four adults were classified as Type A or B by means of the Jenkins Activity Survey, and as Runner or Sedentary using self-reports of physical activity. Under challenging instructions, subjects performed a primary task (Raven Advanced Progressive Matrices) and secondary task (Backward Digit Span) alternatively under single and dual task conditions. There was a significant interaction between aerobic fitness and task condition such that Runners outperformed Sedentary subjects under dual, but not single, task conditions on the secondary task. No differences were found on the primary task. Backward Digit Span performance under dual, but not single, task conditions, was also found to be positively related to the subjects eating a low cholesterol diet and maintaining a healthy weight. Contrary to predictions, there were no significant effects of the Type A behavior pattern, either main or interaction, on any of the cognitive measures. Type A Runners exceeded Type B Runners in aerobic points, races per year, runs per week, Personal Record attempts, and level of dissatisfaction with performance. There were no differences in the tendency to run while injured, use of a stopwatch during training, or effort exerted in races. Overall, these findings suggest that an ability to perform under split-attention (dual task) conditions is positively related to aerobic fitness, a low-fat diet, and maintenance of a healthy weight. In addition, Type A Runners differ from B Runners in some, but not all, aspects related to the Type A pattern, suggesting that aerobic exercise may modify to a limited extent the Type A behavior pattern. The failure to find A-B differences in attentional style consistent with prior research (Matthews & Brunson, 1979) or interaction of type and exercise may reflect the nature of the sample and tasks in this particular investigation, compared with previous studies.
87

Economical design considerations for one-way 300 foot span, steel, parallel top & bottom chord warren trusses

Heath, Joshua January 1900 (has links)
Master of Science / Department of Architectural Engineering / Kimberly W. Kramer / Trusses are an efficient way to span long distances with minimal material required. This report is a parametric study of the different design and construction aspects for a 300’-0” span, steel, Warren type truss. The study specifically examines the vertical loading on the truss, including components and cladding wind loading. The engineering variables investigated are panel point location, steel shape size and type, steel grade, member orientation, and connection design. Each of these aspects are studied independently with major results accounted for later in analysis. This allows for the most economical truss by reviewing each alternative possibly not commonly used in steel construction. However, trusses require special consideration in constructability compared to a common steel structure such as an office building. Because of this added complexity, constructability issues are also examined after all parametric studies are completed for engineering variables. Transportation regulations and restrictions, steel erecting (including the construction loading of the ASCE 37-02), and temporary structures are considered for the 300’-0” span steel truss. The results of the engineering design variables are documented showing the benefit of using W-Shape members with higher grades of steel in select members, and the rotation of members for truss stability and simplified connection detailing. Each of the multiple construction considerations are presented, providing the most recent information available at the time of this report.
88

Developing short-span alternatives to reinforced concrete box culvert structures in Kansas

Handke, John Michael January 1900 (has links)
Master of Science / Department of Civil Engineering / Robert J. Peterman / Concrete box culvert floor slabs are known to have detrimental effects on river and stream hydraulics. Consequences include an aquatic environment less friendly to the passage of fish and other organisms. This has prompted environmental regulations restricting construction of traditional, four-sided box culvert structures in rivers and streams populated by protected species. The box culvert standard currently used by the Kansas Department of Transportation (KDOT) is likely to receive increased scrutiny from federal and state environmental regulators in the near future. Additionally, multiple-cell box culverts present a maintenance challenge, since passing driftwood and debris are frequently caught in the barrels and around cell walls. As more structures reach the end of their design lives, new solutions must be developed to facilitate a more suitable replacement. Since construction can cause significant delays to the traveling public, systems and techniques which accelerate the construction process should also be considered. This thesis documents development of a single-span replacement system for box culverts in the state of Kansas. Solutions were found using either a flab slab or the center span of the KDOT three-span, haunched-slab bridge standard. In both cases, the concrete superstructure is connected monolithically with a set of abutment walls, which sit on piling. The system provides an undisturbed, natural channel bottom, satisfying environmental regulations. Important structural, construction, maintenance, and economic criteria considered during the planning stages of bridge design are discussed. While both superstructural systems were found to perform acceptably, the haunched section was chosen for preliminary design. Rationale for selection of this system is explained. Structural modeling, analysis, and design data are presented to demonstrate viability of the system for spans ranging from 32 to 72 feet. The new system is expected to meet KDOT’s needs for structural, environmental, and hydraulic performance, as well as long-term durability. Another option involving accelerated bridge construction (ABC) practices is discussed.
89

Caracterização da tolerância ao estresse oxidativo, capacidade de remoção de proteínas oxidadas e a expectativa de vida de linhagens da levedura S. cerevisiae com mutações sítio-específicas na subunidade α5 do proteassomo 20S: implicações na prevenção de agregação. / Characterization of tolerance to oxidative stress, capacity to remove oxidized proteins and the life span of the yeast S. cerevisiae with site-specific mutations in the α5 subunit of the 20S proteasome: implications in the prevention of protein aggregation.

Ohara, Erina 04 September 2015 (has links)
O proteassomo é um complexo proteico responsável pela degradação de proteínas poli-ubiquitinadas. É constituído por uma unidade catalítica denominada de proteassomo 20S (20SPT) e por unidades regulatórias (19S) acopladas em uma ou ambas as extremidades para formar o proteassomo 26S. O 20SPT é capaz de degradar proteínas por um processo independente de ATP e ubiquitina. Este mecanismo é considerado preventivo de agregação proteica, uma vez que o acúmulo de proteínas oxidadas está diretamente associado ao envelhecimento e doenças neurodegenerativas. Foi observado pelo grupo que o 20SPT da levedura S.cerevisiae sofre S-glutatiolação nos resíduos de Cys 76 e Cys 221 da subunidade 5. Dados obtidos por microscopia eletrônica de transmissão mostraram que a S-glutatiolação promove a abertura da câmara catalítica e consequentemente o aumento da degradação de proteínas. Recentemente, foram obtidas linhagens com mutações sítio-específicas pela substituição dos dois resíduos de Cys glutatioláveis pela Ser. Ensaios realizados com a linhagem C221 mostraram um aumento da longevidade e resistência ao estresse oxidativo quando comparada com a linhagem selvagem, enquanto que a linhagem C76 mostrou uma dificuldade no crescimento. Foi verificado também que a população de proteassomo isolada da linhagem C221 apresenta maior proporção da forma aberta da câmara catalítica. Resultados opostos foram observados na linhagem C76S. No entanto, constatamos um aumento de proteínas oxidadas e de agregados proteicos na linhagem C221 em comparação a selvagem. Esses dados não condizem com o aumento do tempo de vida cronológico desta linhagem, porém acreditamos que esses agregados estejam relacionados a um tipo de sequestro de proteínas potencialmente prejudiciais, como será discutido neste trabalho. / The proteasome is a protein complex responsible for the degradation of poly-ubiquitinated proteins. It comprises a catalytic unit called 20S proteasome (20SPT) and regulatory units (19S) coupled at one or both ends to form the 26S proteasome. The 20SPT is able to degrade proteins by an ATP and ubiquitin independent process. This mechanism is considered preventive of protein aggregation, since the accumulation of oxidized proteins is directly related to aging and neurodegenerative diseases. It was observed by our group that the yeast 20SPT (S. cerevisiae) is modified by S-glutathiolation in the residues Cys 76 and Cys 221 of the 5 subunit. Data obtained by transmission electron microscopy showed that the S-glutathiolation promotes the opening of the catalytic chamber and consequently increased degradation of oxidized proteins. Recently, strains were obtained by site-specific mutations by replacing the two glutathiolable Cys residues by Ser. Tests performed with the C221 strain showed an increased longevity and resistance to oxidative stress when compared to the wild type strain, whereas the C76 strain showed a slower growth. It was also found that the isolated population of the 5-C221S proteasome presents the highest frequency of open catalytic chamber conformation. Opposite results were observed in the C76S lineage. However, we noted an increased pool of oxidized proteins and protein aggregates in the C221 strain compared to the wild type. These data do not match with the increase of chronological life span observed in this lineage, but we believe that these aggregates are related to a kind of \"sequestration\" of potentially damaging proteins, as will be discussed in this work.
90

Os 120 anos da vida do homem: uma análise contextual / The 120 years of human life: a contextual analysis

Hubner, Manu Marcus 14 August 2015 (has links)
Através dos números, os homens são capazes de comparar, ordenar, medir e quantificar tudo o que há à sua volta. Além da sua utilização para a matemática, muitos números receberam significados simbólicos. Na Bíblia Hebraica, os números são freqüentes, e possuem diversas funções e significados. Alguns números se destacam, como é o caso do número cento e vinte, utilizado para medidas ou contagens de tempo, espaço (áreas ou territórios), peso, pessoas ou animais. Este número figura no Livro do Gênese (6:3), como medida de tempo, no momento em que um limite de cento e vinte anos é decretado como expectativa máxima de vida do homem uma punição às transgressões do homem, falível e mortal, comparável à expulsão de Adão e Eva do Jardim do Éden (Gn 3:23-24) ou à diversificação das línguas faladas durante o episódio da Torre de Babel (Gn 11:7). Este decreto é estabelecido em uma interpolação de uma narrativa lacônica, aparentemente mitológica, em que seres conhecidos como filhos de Deus se relacionam com as filhas dos homens, dando origem a descendentes conhecidos como gigantes ou heróis. O número cento e vinte está relacionado ao período de cento e vinte anos em que Noé construiu a arca para sobreviver ao dilúvio (Gn 6), aos cento e vinte dias em que Moisés esteve sobre o Monte Sinai em três períodos de quarenta dias cada (Ex 24:12-18, 32:15, 30-31, 34:4, 29), como também ao período de três gerações convencionais de quarenta anos cada, exemplificado pelo pacto de Deus com o povo de Israel: ...guardes todos os Seus estatutos e os Seus preceitos que eu te ordeno tu, teu filho e o filho de teu filho... (Dt 6:2). Assim, apesar de que o número cento e vinte possui uma quantidade enorme de divisores, sua subdivisão em três períodos ou gerações de quarenta anos cada possui um simbolismo que instiga a investigação. / Through the numbers, men are able to compare, sort, measure and quantify everything there is around them. Besides their use for mathematics, many numbers have symbolic meanings. In the Hebrew Bible, numbers are frequent, and have different functions and meanings. Some numbers are highlighted, such as the number one hundred and twenty, used to measure or counting of time, space (areas or territories), weight, people or animals. This number can be found in the Book of Genesis (6:3), as a measure of time, at the moment when a limit of one hundred and twenty years is decreed as the maximum life expectancy of man a punishment for man\'s transgressions comparable to the expulsion of Adam and Eve from the Garden of Eden (Gen. 3:23-24) or the confusion of speech during the episode of the Tower of Babel (Gen. 11:7). This decree is established on an interpolation of a seemingly mythological, laconic narrative in which beings known as the \"sons of God\" had relationships to the \"daughters of men\", giving rise to offspring known as \"giants\" or \"heroes\". The number one hundred and twenty is related to the period of one hundred and twenty years in which Noah built the ark to survive the flood (Gen. 6), to one hundred and twenty days in which Moses was on Mount Sinai in three forty-day periods each (Ex 24 :12 -18 , 32:15 , 30-31 , 34:4, 29), as well as the conventional period of three generations of forty years each, exemplified by the covenant of God with the people of Israel: \" ... keep all His rules and laws that I am prescribing to you you, your children and your childrens children\" (Deut. 6:2). Thus, although the number one hundred and twenty has a huge amount of dividers, its subdivision into three periods or generations of forty years each has a symbolism that instigates the investigation.

Page generated in 0.0281 seconds