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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.
101

Gradient formation in cemented carbides with 85Ni:15Fe-binder phase / Gradientbildning i hårdmetall med 85Ni:15Fe-bindefas

Larsson, Niklas January 2015 (has links)
In today’s inserts used for metal cutting the binder phase consists of cobalt (Co).However, EU’s REACH programme and the U.S’s National Toxicity Programme(NTP) classified Co as toxic/carcinogenic. Therefore, there is a strong need toinvestigate alternative binder phases. This thesis covers sintering and characterisationof cemented carbide with a binder phase consisting of nickel (Ni) and iron (Fe) withthe composition of 85Ni:15Fe. The aim was to study the gradient formation of turninginsert and find sintering processes to achieve a gradient structure with the targetedthickness of 26 microns. Simulations in ThermoCalc provided a suitable composition and a starting point forsintering parameters. The influences of sintering process parameters, such as holdingtime, temperature and counter pressure on the formation of the gradient zone wereinvestigated. Hot isostatic pressing (HIP) sintering was done in order to study thegradient formation as well as to reduce the porosity when needed. Sintered insertswere analysed by light optical microscopy. It was found that there are at least three possible ways to control the formation ofthe gradient: sintering in vacuum with a holding time of 20 min at 1450°C, sintering at1450°C with a counter pressure of 5 mbar nitrogen, and sintering with a counterpressure of 11.5 mbar followed by a double sinter-hip with 55 bar argon atmosphere.However, only the last process fulfilled the microstructure criteria in terms ofporosity and binder phase distribution. It is clear that the formation of gradient zonesin 85Ni:15Fe can be predicted, however calculations and simulations need to beoptimized in order to get more accurate results.
102

The Effects of the Self-Determined Learning Model of Instruction on the Self-Determination and Goal Attainment of Deaf and Hard-of-Hearing Middle School and High School Students

Spolsky, Sonya Christine January 2014 (has links)
Promoting student self-determination has been identified as best practice in special education as an effective way to promote goal attainment and successful post school outcomes for students with disabilities. There have been, however, limited evaluations of the effects of interventions to promote self-determination with students who are deaf or hard-of-hearing. This study reports finding from a quasi-experimental switching replication study examining the impact of intervention using the Self-Determined Learning Model of Instruction on student self-determination and goal attainment for students who are deaf or hard-of-hearing. Findings within this study using the current research design and limited sample do not support the efficacy of the model for differential goal attainment and goal attainment facilitation by Group assignment but students who are classified as DHH were able to set goals and attain these at a better than expected level of progress. Measures of self-determination used in this study proved to have good internal reliability with students who have various levels of hearing loss and who use various modes of communication.
103

The Effects of Testing Accommodations Usage on Students' Standardized Test Scores for Deaf and Hard-of-Hearing Students in Arizona Public Schools

Wolf, Jennifer January 2007 (has links)
The Individuals with Disabilities Education Act (IDEA) and the No Child Left Behind (NCLB) Act mandate all children be included in state and district assessments to measure their progress. IDEA, NCLB, and the Americans with Disabilities Act (ADA) require students have access to accommodations necessary for their participation in mandated testing. Due to problems secondary to their disability, students who are deaf and hard-of-hearing (D/HH) may have difficulty participating in testing programs designed for the general population. In order to have equal access to standardized testing, D/HH students may need to use testing accommodations.The purposes of this study were to: a) document the use of testing accommodations by students who are D/HH, b) identify the types and frequency of testing accommodations required by D/HH students attending general education classes in Arizona public schools, and c) to analyze the relationships between type and degree of hearing loss and SAT-9 achievement for students who are D/HH in Arizona public schools.The participants included 62 students in the first year of the study, and 53 students in the second year. All participants had diagnosed hearing losses and attended general education classes with support from teachers of the D/HH and/or other support personnel.Extended Time was the most frequently required accommodation. Principal components analysis resulted in clustering of accommodations variables into three components in 2002: Time and Administration, Presentation, and Student Directed, and four components in 2003: Presentation and Administration, Time and Materials, Response, and Student Directed. The accommodations used and their clustering were similar to those reported in the literature. Type of hearing loss was found to significantly affect reading achievement even when controlling for testing accommodations. The interaction between type and degree of loss significantly affected language achievement. Results demonstrated the reading and language achievement performance of students with mild and high frequency hearing loss fell behind students having greater levels of hearing loss. The use of testing accommodations resulted in mixed effects on student reading and language achievement performance. Changes in language scores, but not in reading scores, were found.
104

Ytstrukturer och processer för hårdbearbetning av kugghjul och axlar / Surface texture and processes for hard part machining of coggwheels and shafts

Hjertstedt, Johan January 2008 (has links)
Detta examensarbete har utförts vid Linköpings universitet i samarbete med Scania Transmission i Södertälje och behandlar kravsättning av ytstrukturer samt processer för hårdbearbetning av kugghjul och axlar. Aktuella artikelritningar innefattar endast krav för Ra-värde, den aritmetiska medelavvikelsen för ytjämnhetsprofilen (R-profilen). Förslag på nya parametrar enligt av Scania tillämpade SS-EN ISO standards har tagits fram, detta för att ge en noggrannare beskrivning av vilken ytstruktur som skall uppnås. Resultatet är generellt tillämpningsbart men fokuseras mot kugghjulens hål, plan och diametrar. Vidare presenteras en jämförelse mellan metoder så att transmissionsverkstäderna kan tillverka kugghjul/axlar på ett kostnadseffektivare sätt. Arbetet grundas på en litteraturstudie av handböcker och standards kompletterat med kartläggning av nuläget genom insamling av mätdata. En omvärldsanalys och några bearbetningsprover med hårdsvarvning har också utförts. Till skillnad från nuläget föreslås en övergång från att ange Ra-värde på ritningarna till att ange en övre gräns för Rz-värde som en begränsning av amplituden. Ytor i relativ rörelse och ytor som ingår i pressförband föreslås kompletteras med en undre gräns för Rz-värde samt en undre gräns för relativ bärighet. Med införandet av ett bärighetskrav ges även en specifikation för profilens fördelning. Angivelse av bearbetningsmetod och eventuellt bearbetningsmönster föreslås att anges i klartext på ritningen då parametrar som beskriver karakteristiska drag för olika bearbetningsmetoder visat sig väldigt variationsbenägna i nulägesanalysen. Jämförelse av hårdbearbetningsmetoder har visat att det i kombinationsmaskiner, hårdsvarvning och slipning, vore intressant att enbart hårdsvarva kugghjulens glidlagerytor, något som enligt bearbetningsprover och omvärldsanalys verkar rimligt. Detta bör efter godkännda riggprover anammas som ett första optimeringssteg. Fler intressanta koncept för framtida bearbetningsalternativ finns att studera i rapportens resultat och diskussionskapitel. / This master thesis report was performed at Linköpings University in cooperation with Scania Transmission in Södertälje and deals with specification of surface textures and processes for hard part machining of cogwheels and shafts. Present blueprints only include requirements for Ra-values, arithmetic mean deviation of the roughness profile (R-profile). Suggestions of new parameters according to SS-EN ISO standards used by Scania have been compiled with the aim of providing a more accurate description of the surface texture that is to be achieved. The result can be applied in general but are focused towards holes of cogwheels, planes and diameters. Furthermore a comparison between different methods is presented so that the transmission workshops can manufacture cogwheels and shafts in a costefficient manner. The work is based on a comparative literature study of handbooks and standards with complementary documentation of the present situation through collecting of measurements. A reference analysis and a few manufacturing tests of hard turning have also been performed. In difference from the present situation a transition from providing Ra-values on the blueprints to specify an upper limit for Rz-value to restrict the amplitude is recommended. Surfaces in relative motion and surfaces in heavy force fit are suggested to be complemented with a lower limit for Rz-values and a lower limit for relative material ratio. With an introduction of material ratio requirements the profiles distribution are also specified. Denunciation of manufacturing method and surface lay if any is suggested to be stated en clair on the blueprint being so that parameters describing characteristic features for different manufacturing methods have shown a wide range of distribution in the present state analysis. Comparison of hard part machining methods have shown that in combination machines, hard turning and grinding, solely hard turning of the cogwheels slide bearing surfaces would be interesting, which also seems plausible due to manufacturing samples and the reference analysis. After approved rigg tests this method can be adopted as a first step of optimization. More interesting concepts for future manufacturing alternatives are provided in the reports result and discussion chapters.
105

Design fires in underground hard rock mines

Hansen, Rickard January 2011 (has links)
During several decades considerable research activities have been conducted with respect to fires in coal mines, but the research activities with respect to hard rock mines have been limited. As the hard rock mines are getting more complex the need for deeper understanding of fires in underground hard rock mines are getting more in demand. The more urgent demands are the need for more specific heat release rate curves as design fires, applicable fire experiments and any method that would allow for the calculation of the total heat release rate curve of an object. This thesis presents a number of examples on design fire curves applicable to underground hard rock mines; it also presents the results of model scale fire experiments and methods for calculating the total heat release rate of several objects at uniform as well as non-uniform conditions. Tests were carried out in a model scale tunnel using wooden pallets as fire load. The parameters tested were the distance between piles of pallets and longitudinal ventilation rate. It was found that an increasing ventilation rate also increases the peak heat release rate. When studying the curves of heat release rates it was found that when the distance between the ignited pile and the second pile increased to a certain level the delayed ignition of the second pile will result in that the peak heat release rate of the adjacent piles will not occur simultaneously. The ignition data indicated that the ignition time of adjacent piles decreased as the longitudinal ventilation increased.  A method using a critical heat flux as ignition criterion exhibited very good agreement with the corresponding experiments for both uniform as well as non-uniform conditions. The methods using the ignition temperature as ignition criterion did not agree very well with any of the corresponding experiments. / GRUVAN
106

Conformational Change in the Structure of Wheat Proteins During Mixing in Hard and Soft Wheat Doughs

Jazaeri, Sahar 19 March 2013 (has links)
This thesis describes an investigation of the mechanistic differences of hard and soft wheat varieties in the course of dough formation. These two classes of wheat exhibit dissimilar end-use, as hard wheat flour is known for its bread making attributes, whereas soft wheat flour is suitable for cake and cookie production. This difference is related to the grain hardness, protein content and property of gluten, in addition to chemical interactions that are occurring during dough making. Covalent and hydrophobic interactions, as well as hydrogen bond formation, are the main interactions that take place during dough mixing. However, the contribution of each interaction in dough formation of hard and soft wheat is not known. One variety of hard and one variety of soft wheat flour were mixed to their optimum hydration level (500 BU), as determined by farinograph. The extent of covalent interactions of gluten proteins during dough mixing was examined by monitoring changes in the solubility of flour proteins in a 2% Sodium Dodecyl Sulfate (SDS) media. Moreover, the contribution of thiol groups to covalent bond was examined by measuring the changes in the accessible thiols throughout the mixing. Lower extractability of proteins and accessible thiols of hard wheat dough, compared to soft wheat dough, indicated the predominant role of covalent interactions in hard wheat dough. The complementary results from Size Exclusion High Performance Liquid Chromatography (SE-HPLC) indicated that covalent interaction of hard wheat dough primarily occurs between Low Molecular Weight (LMW) and High Molecular Weight (HMW) gluten proteins, whereas this interaction mainly occurs among LMW proteins in soft wheat doughs. Fewer hydrophobic interactions in hard wheat dough in compare with soft wheat measured by Front-face fluorescence spectroscopy indicated that this interaction is more dominant in soft wheat dough. Study of the conformational change in secondary structure of protein (indirect approach to monitor hydrogen bond) by fourier transform infrared (FTIR) spectroscopy showed that β-sheets are formed in both varieties at their optimum dough strength. In hard wheat dough this structure resulted mainly from disulfide linkages, whereas in soft wheat dough this structure is more likely the result of hydrophobic interactions.
107

Learning to listen: the voices of post-secondary deaf and hard of hearing learners

Martin, Deena Unknown Date
No description available.
108

Surface integrity and tool performance in the turning of hardened steel

Galéa, Vincent 05 1900 (has links)
No description available.
109

Investigation of CaIr1-xPtxO3 and CaIr0.5Rh0.5O3 : structural properties, physical properties and stabilising conditions for post-perovskite oxides

Hirai, Shigeto January 2011 (has links)
Our understanding of the nature of Earth’s D” region was changed significantly by a recent finding by Murakami et al. (2004), who revealed a phase transition from perovskite to post-perovskite structure in MgSiO3 at about 125 GPa and 2500 K, corresponding to conditions of the lowermost mantle. A perovskite to post-perovskite phase transition accounts for many unusual features of the D” region, including its notable seismic anisotropy, and also accounts for the unusual topology of the D” discontinuity. However, the experimentally synthesised post-perovskite phase of MgSiO3 is not quenchable to ambient conditions, which means that many of its physical properties remain difficult to determine. On the other hand, there are several post-perovskite oxides, CaIrO3, CaPtO3, CaRhO3 and CaRuO3, which can be quenched to ambient conditions, maintaining their structure. High pressure synthesis of CaIr1-xPtxO3 solid solutions (x = 0, 0.3, 0.5, 0.7) and CaIr0.5Rh0.5O3 was conducted at the University of Edinburgh and Geodynamics Research Center, Ehime University, and structures and physical properties of these novel post-perovskite materials determined. Substantial [100] grain growth was observed in all solid solutions leading to pronounced texture even in powdered materials. Temperature-independent paramagnetism above 150 K and small magnetic entropy observed in heat capacity measurements suggest that CaIrO3 is an intrinsically weak itinerant ferromagnetic metal, while electrical resistivity measurements show that it is a narrow bandgap semiconductor, possibly due to grain boundary effects. CaIrO3 undergoes a magnetic transition at 108K and possesses a saturated magnetic moment of 0.04 μB. Doping with Pt or Rh induces Curie-Weiss paramagnetism and suppresses the magnetic transition. The anisotropic structure and morphology of CaIrO3 combined with the Ir4+ spin-orbit coupling results in a large magnetic anisotropy constant of 1.77 x 106 Jm-3, comparable to values for permanent magnet materials. A new high-pressure phase of CaIr0.5Pt0.5O3 was synthesised at 60GPa, 1900K using a laser-heated DAC (diamond anvil cell) at GRC, Ehime University. Its Raman spectra resemble those of perovskite phases of CaIrO3 and CaMnO3, implying that CaIr0.5Pt0.5O3 undergoes a post-perovskite to perovskite phase transition with increasing pressure. I estimate an increase in thermodynamic Grüneisen parameter γth across the post-perovskite to perovskite transition of 34 %, with similar magnitude to (Mg,Fe)SiO3 and MgGeO3, suggesting that CaIr0.5Pt0.5O3 is a promising analogue for experimentally simulating the competitive stability between perovskite and post-perovskite phase of magnesium silicates in Earth’s lowermost mantle. Such estimation is reliable since the estimated and directly calculated thermodynamic Grüneisen parameter γth from heat capacity show consistent values. The marked effect that Pt has on stabilising the post-perovskite structure in CaIr1-xPtxO3 solid solutions explains why the post-perovskite to perovskite phase transition has not been observed for CaPtO3 in contrast to other quenchable post-perovskite oxides: CaIrO3, CaRhO3 and CaRuO3.Work presented here demonstrates that CaIrO3 solid solutions can be used to provide new insight into factors stabilising post-perovskite structures in Earth’s lowermost mantle.
110

Hur kan musicerande bedömas på högstadiet? : En studie om bedömningar inom musikämnet

Forsberg-Ödmark, Helena January 2014 (has links)
I studien har undersökts vilka kunskaper och färdigheter som elever i årskurs 9 värdesätter och anser som mest väsentliga att bedöma inom sång och ensemblespel och relatera dessa bedömningar till de nationella mål och kriterier som har fastställts för ämnet musik. Jag har använt mig av kvalitativ samtalsintervju som undersökningsmetod och begränsat mig till att undersöka sexton elever, 8 pojkar och 8 flickor, som jag undervisar i musik på en högstadieskola i Mellansverige. Undersökningen utgår från ett fragmatiskt- och sociokulturellt perspektiv på lärande. Resultatet belyses också utifrån formativ bedömning i undervisning och betydelsen av att använda bedömningsmatriser för att tydliggöra för eleverna vad som de förväntas lära sig. Resultatet visar att en gemensam syn på bedömning är viktig för att eleverna ska veta på vilken kunskapsnivå de befinner sig på men även för att de ska veta vad de behöver förbättra. Bedömning är en förutsättning för betygsättning och det finns en stor enighet om vad eleverna anser som väsentligt att bedöma inom musikämnet. Vissa olikheter existerar mellan vad respondenterna anser om att bli bedömda i sång. Andra anser att det är alltför personligt och svårt för en del elever att lära sig sjunga.

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