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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.
1

Rychlostní charakteristiky hráčů fotbalu / Velocity characteristics of soccer players

Červenka, Daniel January 2019 (has links)
Title: Velocity characteristics of soccer players Objectives: The main goal of the thesis id to evaluate and analyze velocity and agility abilities of elite players. Analyze the change direction in velocity in the form of acceleration and deceleration turn over to the opposite direction. Compare the movement task session to the right and left rotating lower limb. Methods: Measured group consisted of 35 players with these athropometric values (age = 20±3,25 years, height = 187 ± 0,648 m, weight = 72 ± 3.25 kg). Players completed the warm-up prior to testing (activation stretching, stretching, warm up and subsequent motion game). Measured tested portion was 5m, followed by turning on the predefined leg and running backwards to the photocell gate (test 505). Each player completed 2 attemps on the right and 2 attemps on the left leg. Method for evaluating the kinematics used 2D video analysis. For video processing software was used Bio TEMA (ImageSystems Ltd., Sweden). Results: Players in test of velocity achieved different times on rotation right and left side. However these differences were not significant. In the first step of slowing and accelerating players do not reach comparable velocity. They can compare velocity on the second step. On right side players will use the stride length at step 2 and...
2

The effect of submerged arc welding parameters on the properties of pressure vessel and wind turbine tower steels

Yang, Yongxu 21 October 2008
Submerged arc welding (SAW) is commonly used for fabricating large diameter linepipes, pressure vessels and wind turbine towers due to its high deposition rate, high quality welds, ease of automation and low operator skill requirement. In order to achieve high melting efficiency required for high productivity, best weld quality and good mechanical properties in manufacturing industries, the welding process parameters need to be optimized. In this study, the effect of SAW current and speed on the physical and mechanical properties of ASME SA516 Gr. 70 (pressure vessel steel) and ASTM A709 Gr. 50 (wind turbine tower steel) were investigated. Three welding currents (700 A, 800 A and 850 A) and four travel speeds (5.9, 9.3, 12.3 and 15.3 mm/s) were used to weld sample plates measuring 915 mm x 122 mm x 17 mm. The weld quality and properties were evaluated using weld geometry measurements, visual inspection, ultrasonic inspection, hardness measurements, optical microscopy, tensile testing, Charpy impact testing and scanning electron microscopy. It was found that the physical and mechanical properties of the weldments were affected by SAW parameters. Severe undercuts were found at high travel speed and welding current. Low heat input caused lack of penetration defects to form in the weldments. The welding process melting efficiency (WPME) achieved was up to 80%. The hardness of the coarse grain heat affected zone (CGHAZ) and the weld metal increased with travel speed. The toughness of both materials increased with increasing travel speed and welding current. The yield and tensile strengths of the weldments of SA516 Gr.70 and A709 Gr.50 steels were within the same range as those of their respective parent metals because all test specimens broke in the parent metals. Also, the parent metals of both steels had the highest fracture strain and percent elongation. The percentage elongation increased with travel speed but decreased with welding current.
3

The effect of submerged arc welding parameters on the properties of pressure vessel and wind turbine tower steels

Yang, Yongxu 21 October 2008 (has links)
Submerged arc welding (SAW) is commonly used for fabricating large diameter linepipes, pressure vessels and wind turbine towers due to its high deposition rate, high quality welds, ease of automation and low operator skill requirement. In order to achieve high melting efficiency required for high productivity, best weld quality and good mechanical properties in manufacturing industries, the welding process parameters need to be optimized. In this study, the effect of SAW current and speed on the physical and mechanical properties of ASME SA516 Gr. 70 (pressure vessel steel) and ASTM A709 Gr. 50 (wind turbine tower steel) were investigated. Three welding currents (700 A, 800 A and 850 A) and four travel speeds (5.9, 9.3, 12.3 and 15.3 mm/s) were used to weld sample plates measuring 915 mm x 122 mm x 17 mm. The weld quality and properties were evaluated using weld geometry measurements, visual inspection, ultrasonic inspection, hardness measurements, optical microscopy, tensile testing, Charpy impact testing and scanning electron microscopy. It was found that the physical and mechanical properties of the weldments were affected by SAW parameters. Severe undercuts were found at high travel speed and welding current. Low heat input caused lack of penetration defects to form in the weldments. The welding process melting efficiency (WPME) achieved was up to 80%. The hardness of the coarse grain heat affected zone (CGHAZ) and the weld metal increased with travel speed. The toughness of both materials increased with increasing travel speed and welding current. The yield and tensile strengths of the weldments of SA516 Gr.70 and A709 Gr.50 steels were within the same range as those of their respective parent metals because all test specimens broke in the parent metals. Also, the parent metals of both steels had the highest fracture strain and percent elongation. The percentage elongation increased with travel speed but decreased with welding current.
4

Influencia do grau de mineralização do substrato dentinario na resistencia a microtração de tres sistemas adesivos

Erhardt, Maria Carolina Guilherme 31 January 2003 (has links)
Orientador: Luiz Andre Freire Pimenta / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba / Made available in DSpace on 2018-08-03T17:59:19Z (GMT). No. of bitstreams: 1 Erhardt_MariaCarolinaGuilherme_M.pdf: 5117640 bytes, checksum: d255d8edb48804d7128e30ab7907508a (MD5) Previous issue date: 2003 / Resumo: O objetivo deste estudo in vitro foi determinar a influência de superfícies dentinárias desmineralizadas, normais e hipermineralizadas na resistência adesiva (RA) dos sistemas adesivos Clearfil Liner Bond 2V / Kuraray Co. (CLB), Single Bond /3M (SB) e OptiBond Solo P/us / Kerr (OSP). Noventa incisivos bovinos foram selecionados, tendo suas superfícies vestibulares desgastadas com lixas de carbeto de silício em granulação decrescente. Os dentes foram aleatoriamente separados em três grupos, sendo submetidos a diferentes padrões de ciclagem de pH: G1 - dentina desmineralizada (DD)i G2 - dentina hipermineralizada (DH) e G3 - dentina normal (DN). Cada grupo, com seus respectivos padrões de superfície, foi novamente dividido por aleatorização em três subgrupos, para que recebessem a aplicação de um dos três sistemas adesivos, de acordo com a recomendação dos fabricantes. Blocos de compósito Filtek Z250 / 3M com altura de 5 mm foram incrementalmente confeccionados, e após 24 h de armazenagem em água destilada a 37 °C, os dentes foram preparados para serem submetidos ao teste de microtração. Dispostos em cortadeira metalográfica de precisão, os dentes foram seriadamente seccionados em fatias de 1,0 mm de espessura paralelamente ao longo eixo dental. Em seguida, dispositivos hour glass foram manualmente confeccionados com o auxílio de pontas diamantadas de granulação fina em alta rotação, com área adesiva final de 0,8 mm2. Os espécimes foram afixados individualmente em um dispositivo de microtração (MT Jig), acoplada em máquina de ensaio universal / EMIC, com velocidade de 0,5 mm/min. Após o teste, as duas porções fraturadas foram avaliadas em microscópio óptico (40x). Os valores de RA foram submetidos aos testes de análise de variância (ANOVA 2 fatores) e Tukey, com nível de significância de 5%. Os valores médios, expressos em MPa, foram: DN;SB= 31,05; DN/OSP= 24,49; DH;SB= 23,97; DH/CLB= 19,32; DN/CLB= 19,00; DH/OSP= 17,84; DD/CLB= 15,81; DD;SB= 13,62i DD/OSP= 5,22. Houve interação estatística entre os sistemas adesivos e os tipos de dentina avaliados. Em DN, os sistemas adesivos SB e OSP foram significativamente mais efetivos que o adesivo CLB. Em DD, os adesivos SB e CLB apresentaram os maiores valores de RA. Em DH, todos os sistemas adesivos se comportaram de maneira semelhante. Não foi possível observar um benefício claro advindo da utilização de um único sistema adesivo em todos os níveis de mineralização dentinária / Abstract: The purpose of this in vitro study was to investigate the effect of dentin mineralization level: demineralized, normal or hypermineralized, on microtensile bond strength of the adhesive systems Clearfil Liner Bond 2V / Kuraray Co. (CLB), Single Bond / 3M (SB) and OptiBond Solo Plus / Kerr (OSP). 90 freshly extracted incisive bovine teeth were selected, thoroughly cleaned and mechanically polished with wet silicon carbide papers. Teeth were randomly assigned into three groups, which were submitted to different pH-cycling models: Group I - demineralized dentin (DD); Group II - hypermineralized dentin (HD) and Group III normal dentin (ND). Each group, with its specific mineralization pattern, was randomly reassigned into three subgroups, in order to receive one of each adhesive application, according to manufacturers' instructions. Resin "crowns" with 5 mm high were incrementally constructed with Filtek Z250 /3M composite resin, and after 24 h of storage in distilled water at 37°C, teeth were prepared to micro-tensile testing. Samples were serially sectioned on a precision cutter in 1 mm slices, parallel to the dental long axis; and with diamond points, the hour glass devices were trimmed resulting in a cross-sectional area of 0.8 mm2. Each specimen was indMdual1y tested on a microtensile device (MT Jig) attached to a universal testing machine / EMIC with a crosshead speed of 0.5 mm/min. After testing, each specimen was visually evaluated. The bond strengths were statistically evaluated with two-way ANOVA and Tukey's test (p<0.05). The mean values obtained, recorded in MPa, were: ND;SB= 31.05; ND/OSP= 24.49; HD;SB= 23.97; HD/CLB= 19.32; ND/CLB= 19.00; HD/OSP= 17.84; DD/CLB= 15.81; DD;SB= 13.62; DD/OSP= 5.22. The statistical analysis showed a significant (p<0.05) interaction between the adhesive systems and the dentin substrates evaluated. SB and OSP presented the higher tensile bond strength values on ND. In terms of tensile bond strengths to DD, the highest mean values originated from SB and CLB. Regarding the HD, no differences were found among the adhesive systems evaluated. It could not be observed a real benefit from a unique adhesive system in all dentin mineralization levels / Mestrado / Dentística / Mestre em Clínica Odontológica
5

Durabilité des bétons autoplaçants à base de vase et de pouzzoloane / Drability of self compacting concretes with silt and pozzolan

Belaribi, Omar 28 June 2015 (has links)
RésuméEn raison des spécificités relatives à la formulation des bétons autoplaçants (BAP) et en particulier ceux concernant leur volume élevé en pâte et la présence d'ajouts et substituts minéraux en grande quantité, leur comportement à l'état frais et à l'état durci ainsi que leur durabilité sont fortement influencés par ces deux paramètres.Certains sédiments traités acquièrent des propriétés pouzzolaniques et peuvent être utilisés en tant qu'ajouts ou substituts au ciment. Ceci peut faire de la technologie des bétons une voie privilégiée pour leur valorisation.La présente étude vise à apporter une contribution à la valorisation de la vase traitée du barrage de Chorfa et de Fergoug, (situé à l'ouest algérien) en tant que substitut minéral partiel au ciment CPA CEMI 42.5 dans la composition des mortiers et des bétons autoplaçants. Il s'agit de comparer l'influence de l'incorporation de cette vase calcinée à celle de la pouzzolane naturelle de Béni-Saf (situé, également à l'ouest algérien) dans les BAP sur leurs caractéristiques physico-mécaniques et sur leur durabilité à court, moyen et long terme.L'étude est menée sur quatre BAP, le premier à base de 20 % de pouzzolane naturelle de Béni-Saf (BAP-PZ), le deuxième et le troisième incorporant 20 % de la vase calcinée issue des sédiments de dragage du barrage de Fergoug (BAP-VF) et de celui de Chorfa (BAP-VC) et enfin un BAP témoin sans ajouts pour le besoin de comparaison.Outre l'intérêt économique que présentent les BAP à base de la vase calcinée, notre étude a montré que ces derniers représentent des performances très comparables à celles obtenues sur des BAP à base de pouzzolane naturelle (BAP-PZ).En effet, Concernant les résistances à la compression, notre étude indiquent que les BAP à base de vase ((BAP-VC) et (BAP-VF)) présentent les meilleurs résultats notamment à long terme.Les résultats des essais de l'attaque acide (HCl et H2SO4), l'attaque sulfatique (Na2SO4 et MgSO4) et de carbonatation accélérée, montrent que la vase calcinée a une influence sensiblement meilleure que celle de la pouzzolane sur les propriétés physico-mécaniques et la durabilité des bétons dans lesquels elle est incorporée.Mots clés : Barrage de Chorfa - Barrage de Fergoug –Vase calcinée – pouzzolane – BAP à base de vase – BAP à base de pouzzolane – Résistances mécaniques –Durabilité. / AbstractBecause of the specificities of self-compacting concrete (SCC), especially regarding their high volume paste content and the presence of large amounts of mineral admixtures and substitutes, the behavior in fresh and hardened state and the durability of these concretes are strongly influenced by these two parameters.Some treated sediments acquire pozzolanic properties and can be used as additions orsubstitutes to the cement. This possibility makes of concrete technology a privileged way of enhancement.The present study aims to contribute to the enhancement of the treated mud of Chorfa and Fergoug dam (situated in west of Algeria) as a mineral partial substitute for CPA CEMI 42.5 cement in the composition of an economic and preferment mortars and self-compacting concretes. The aim is to compare the influence of the incorporation of this calcined mud to the natural pozzolana of Beni Saf (situated, also in west of Algeria) in (SCC) on their physical, mechanical behavior and their durability of these concretes in short, medium and long term.The study was conducted on four SCCs, the first based on 20% natural pozzolana Beni Saf (SCC-PZ), the second based on 20% of the calcined mud of Fergoug dam (SCC-VF) and of Chorfa dam (SCC-VC) and a control SCC without additions to the need for comparison .Apart from the economic interest of the SCCs based on calcined mud, our study showed that these concretes have comparable performances to that obtained on SCC based on natural pozzolana (SCC-PZ).In fact, concerning compressive strengths, our study indicate that the SCC with calcined mud ((SCC-VC) and (SCC-VF)) present the best results especially at long termThe results of the different following tests: the acid attack (HCl and H2SO4), carbonation and sulphate attack (Na2SO4 and MgSO4) show that the calcined mud has an influence roughly better than the natural pozzolana on the physic - mechanical behavior and durability of the SCC which it is incorporated.Key words: Dam of Chorfa – Dam of Fergoug – Calcined mud – Pozzolana – SCCcontaining mud - SCC containing pozzolana – Mechanical strength –Durability.
6

Studium lisovacího procesu a vlastností tablet s mikrokrystalickou celulosou a koloidním oxidem křemičitým. / A study of the compaction process and the properties of tablets containing microcrystalline cellulose and colloidal silicon dioxide

Louženská, Markéta January 2015 (has links)
The thesis deals with the comparison of compressibility and properties of tablets containing silicified microcrystalline cellulose and physical mixtures of microcrystalline cellulose with different types of colloidal silicon dioxide. The used excipients were silicified microcrystalline cellulose Prosolv® SMCC 90, microcrystalline cellulose Avicel® PH-102 and colloidal silicon dioxide Aerosil® 200 and 255. Tablets were compressed at three compression forces 2.5, 3 and 3.5 kN. The energy profile of compression, the tensile strength of tablets and the disintegration time of tablets were evaluated. The effect of 1 % magnesium stearate on these parameters under various mixing conditions and its homogenity in the tablet were evaluated. Total energy of compression increased with the growing compression force, it was the highest at Prosolv® SMCC 90. Plasticity decreased with compression force, mixtures of Avicel® PH-102 with both types of Aerosil showed its the highest values. These mixtures provided tablets with lower strength than Avicel® PH-102 and Prosolv® SMCC 90. Disintegration time of tablets increased with the growing compression force and it was longer in the case of tablets from Prosolv® SMCC 90 and Avicel® PH-102. The addition of magnesium stearate decreased tensile strength of tablets most in...
7

Strength proof according to the FKM-Guideline within Creo Simulate

Kölbl, Markus 02 July 2018 (has links)
◦ The strength verification according to FKM with FEM results is time-consuming and requires a separate tool, e.g. KISSsoft. ◦ The strength verification was so far only carried out at individual points of the model. The selection of verification points is usually based on the equivalent stresses. The following influences can not or not sufficiently be considered. ▪ Locally different limit value of strain or plastic notch factor ▪ The location of the most critical combination of stress amplitude and mean stress ▪ The local stress gradient ◦ femMeshFKM was developed from ZF for railway applications (IX), where FEM calculations are performed with Permas. Postprocessing was done in Hyperworks. ◦ For ZF Test Systems, femMeshFKM has been extended to use Creo Simulate data. The postprocessing can be done also in Simulate.

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