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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.
161

Vystružovací nástroje s břity z cermetu a PVD povlakem / Reamers with cermet cutting edge and PVD coating

Technik, Radim January 2009 (has links)
The Master’s thesis is focused on reaming technology using PVD coated reamers with cermet cutting edge. This work point out a historical evolution of reaming technology as well as recent requirements to the quality of produced surfaces. Reamers characteristic, splitting, mechanical designs, cutting tool geometry as well as the assumption of a reamer potential evolution are presented. Application of cermet tool material and PVD coatings to reaming tools is considered. The work contains a review of present statement at reamer market including cermet reamers and provided single cells (elements) of the Tool Management. The experimental part of the work is focused on product manufacture qualities verification of the changeable PVD coated reamer head made by HAM-FINAL ltd. Economic analysis in case of investment to the reamer purchase is demonstrated on the example of the practical application of the reamer.
162

Dokončování přesných ploch frézováním / Finishing milling of accurate surface

Šimonek, Ondřej January 2012 (has links)
The aim of this work is to find a suitable cutting tool and suitable cutting conditions for the production of hydrostatic surfaces of a crossmember with the quality of the surface structure of Ra 0.8 mm. The technology described in the thesis deals with finishing hydrostatic surfaces by milling, with the quality of the surface structure of Ra 0.8mm. As the production method cutting operations using CNC machines is used. To assure the quality of the surface insert tools are used, which are selected and evaluated based on experimental testing from six different suppliers. The technological process of production solves the problem of the hydrostatic surface production from the first gripping all the way to the final manufacture of the surfaces.
163

Uplatnění technologie "reverse engineering" při zhotovení repliky Al odlitku metodou vytavitelného modelu / Using "reverse engineering" approach when making replica of Al casting by lost wax technology

Bezděk, Adam January 2016 (has links)
The aim of this thesis was to produce a prototype casting of aluminum alloy with usage of reverse engineering technology. In a production process surface quality and dimensional accuracy was optimized. 3D scanning, FDM technology, ABSplus surface finishing possibilities and investment casting technology is introduced in theoretical part of this thesis. Practical part of the thesis includes description of original parts, their 3D scanning, usage of RE and RP, production of new castings and evaluation of their dimensional accuracy and surface roughness.
164

Growth performance and meat characteristics of feedlot cattle fed R-salbutamol or zilpaterol hydrochloride during the finishing period

Steenekamp, Stefanie January 2014 (has links)
In this study, 14 typical South African feedlot bulls received no beta-adrenergic agonist for the last 30 days of the finishing period (C), 14 received 120 mg R-salbutamol per animal per day for the last 30 days of the finishing period (S30), 13 received 120 mg Rsalbutamol per animal per day for the last 40 days of the finishing period (S40) and the last group of 13 bulls received 60 mg zilpaterol hydrochloride per animal per day for the last 30 days of the finishing period (Zh). All animals were slaughtered after a 3-day withdrawal period. Parameters included weight gain, feed intake, feed conversion rate, warm and cold carcass mass, dressing %, subcutaneous fat thickness, hide yield %, internal carcass fat distribution, % bone, % fat and % muscle of the prime rib-cut, carcass classification code, conformation, compactness, post-mortem carcass pH profiles, cooking loss, shear force, blood urea nitrogen, creatinine and residue levels of the beta-adrenergic agonists. No differences were observed between any of the four treatment groups concerning live feedlot performance. Bulls receiving the S30 and Zh treatments had lower internal carcass fat distribution compared to C bulls (P <0.05). Bulls receiving the S40 treatment had a lower % fat in the prime rib-cut compared to Zh bulls (P <0.05). Carcasses from S30 bulls had higher pH values 24 hours post mortem compared to carcasses from Zh bulls (P <0.01). Meat samples from Zh bulls had higher shear force, which indicates less tender meat, compared to samples from S40 bulls (P <0.05). Change in serum creatinine levels increased only in Zh treated bulls from the start to the end of treatment and may reflect a higher protein turnover in Zh bulls. The results of this study indicate that R-salbutamol has a more pronounced effect on fat metabolism in feedlot bulls compared to zilpaterol hydrochloride, while zilpaterol hydrochloride has a more pronounced effect on protein metabolism. The residue levels in samples of the liver, kidney, muscle and feaces from zilpaterol hydrochloride and R-salbutamol treated bulls were well below acceptable limits. / Dissertation MSc(Agric)--University of Pretoria, 2014 / gm2015 / Animal and Wildlife Sciences / MSc(Agric) / Unrestricted
165

Prédiction de la composition de la carcasse basée sur le métabolisme des nutriments absorbés : vers une évolution des recommandations alimentaires des jeunes bovins / Dynamic prediction of the carcass composition based on the metabolism of absorbed nutrients : towards an evolution of the dietary recommendations of young bulls

Al-Jammas, Marwa 14 June 2017 (has links)
Le système INRA d’alimentation des Ruminants prédit les réponses de l’animal à des variations d’apports d’aliments ingérés. Toutefois, il évalue mal l’influence de l’alimentation sur la qualité des productions, et en particulier la qualité de la carcasse de bovins dont dépend le paiement des animaux aux producteurs. Pour un type d’animal donné, les poids et composition de la carcasse en lipides et protéines sont prédits par le modèle MECSIC (Hoch et Agabriel, 2004) à partir de l’énergie métabolisable ingérée calculée selon le système INRA de valeur énergétique des aliments et des rations. Or une étude bibliographique suggère que la composition des dépôts dépend aussi pour partie de la composition des rations qui détermine la nature des produits terminaux issus de la digestion des rations et le devenir métabolique des nutriments. Pour tester cette hypothèse, l’objectif fut d’étudier l’effet de la nature de la ration à même quantité énergie métabolisable (EM) ingérée sur la composition des dépôts et de la carcasse. Cet objectif est ciblé sur les bovins mâles en croissance. Les étapes principales de la thèse ont consisté à i) construire une base des données à partir des publications internationales traitant des effets de la variation des rations ingérées sur la composition de la carcasse chez les jeunes bovins, ii) explorer les relations entre la composition de la carcasse et la composition de la ration et sa métabolisabilité. La constitution de la base de données a montré que la composition de la carcasse n’est mesurée que dans 20% des publications, les 80% restantes l’ayant évalué par des mesures indirectes (index USA de rendement de viande, épaisseur de gras sous cutané, persillé, surface de muscle…) qui ne sont pas reliées entre elles. Une étape de recherche préliminaire a été mise en place pour quantifier par méta-analyse les relations entre mesures directes et indirectes de la composition de la carcasse dans le but d’utiliser le maximum de publications pour la suite de la thèse. Nous avons montré que seuls deux indicateurs (index USA de rendement de viande et épaisseur de gras sous-cutané) reflètent correctement la composition de la carcasse et peuvent être utilisés pour établir les lois de variation de sa qualité selon les conditions d’alimentation. Une autre méta-analyse a permis d’explorer à niveaux d’ingestion d’EM similaires, les réponses marginales des dépôts de lipides et protéines dans la carcasse, à des variations strictes de teneurs de la ration en EE, PDI, NDF ou du rapport Amidon/NDF, tout en considérant sa métabolisabilité (q=EM/EB). L’accroissement du rapport Amidon/NDF augmente la teneur en lipides des carcasses mais en deçà d’un seuil de métabolisabilité de la ration de 0,65, i.e. si les rations ont plus de 36% de fourrages. Au-delà de ce seuil, qui correspond à un rapport Amidon/ NDF minimal voisin de 2, il n’y a plus d’effet. Ainsi à même EMI, la composition du gain (et donc l’énergie nette déposée) ne varierait pas linéairement avec la métabolisabilité q de la ration. De plus la teneur en PDI augmente significativement la proportion de lipides de la carcasse (et réduit celle des protéines), surtout si le niveau global d’apports de PDI est limité et ne dépasse pas 2,5 fois les besoins d’entretien en PDI. La teneur en EE a peu d’effets. Ces caractéristiques de ration conduisent à des profils de nutriments (rapport entre nutriments glucogéniques et cétogéniques, azote-alpha-aminé) qui sont aussi discriminants pour la composition de la carcasse. Nos résultats suggèrent qu’il faut considérer les effets de la nature de la ration dans la modélisation de la composition de la carcasse des bovins selon l’EM ingérée. Cela pourra faire l’objet d’une modification significative du modèle de croissance (MECSIC) pour améliorer son pouvoir prédictif. / The INRA feeding system for Ruminants predicts the animal's responses to changes in feed intake. However, it poorly evaluates the influence of feed intake on the quality of productions, and in particular the quality of bovine carcass, on which the payment of animals to the producers depends. For a given type of animal, the carcass weight and its composition in lipids and proteins are predicted by the MECSIC model (Hoch and Agabriel, 2004) from the intake of metabolizable energy calculated from the INRA energy system. However, a literature review suggests that the composition of the depots also partly depends on the composition of the rations, which determines the nature of the digestion end products, and the metabolic fate of the nutrients. To test this hypothesis, the objective was to study the effects of the nature of the ration at similar metabolizable energy intake (MEI) on the composition of the carcass. This study is targeted to growing male cattle. The main steps of the thesis consisted of (i) building a database based on international publications on the effects of dietary intake on carcass composition in young cattle, (ii) exploring the relationships between carcass composition and the composition and metabolisability of the ration. The database showed that the composition of the carcass was measured in only 20% of the publications; the remaining 80% evaluated it by indirect measurements (USA yield grade, fat thickness, marbling, ribeye area ...). A preliminary research step was developed to quantify by meta-analysis the relationships between direct and indirect measurements of carcass composition in order to use the maximum number of publications for the rest of the thesis. We have shown that only two indicators (USA yield grade and fat thickness) correctly reflect the composition of the carcass and can be used to establish the response equations of carcass quality to dietary conditions. Another meta-analysis explored the marginal responses of lipid and protein depots in the carcass to strict variations in the dietary concentrations of EE, PDI, NDF or of the starch / NDF ratio, while considering its metabolisability (q = EM / EB). An increase in the starch / NDF ratio increases the lipid content of the carcasses but below a metabolizability threshold of 0.65, i.e. when rations contain more than 36% fodder. Beyond this threshold, which corresponds to a minimum starch / NDF ratio close to 2, there is no longer any effect. Thus, at similar MEI, the composition of the gain (and therefore the net energy deposited) does not vary linearly with the metabolisability q of the diet. Furthermore, the PDI content significantly increases the proportion of carcass lipids (and reduces that of proteins), especially if the overall level of PDI intake is limited and does not exceed 2.5 fold the maintenance requirements in PDI. The dietary EE content has little effect. These diet characteristics result in nutrient profiles (glucogenic / ketogenic ration, alpha-amino-N) which also discriminate carcass composition. Our results suggest that the effects of the nature of the ration should be considered when modeling the carcass composition of bovine animals from MEI. This should lead to significant changes in the MECSIC growth model to improve its predictive power.
166

Surface Finishing and Corrosion Resistance of 3D Printed Maraging Steel

Shao, Yinan January 2020 (has links)
3D printing, also known as additive manufacturing (AM), has got rapidly developed since 1987. Compared with conventional manufacturing methods, 3D printing provides some advantages such as increasing material utilization and less waste of material. Maraging steel provides good strength and toughness without losing ductility, which has been used for the 3D printing technique. Selective laser melting (SLM) is one of the 3D printing methods, which is mostly used for metal and alloy powder. In this thesis, selective laser melting will be used for maraging steel. 3D printing maraging steel is a new material, the research about the properties of 3D printing maraging steel is still ongoing. Corrosion resistance is one of the most important properties of maraging steel due to the high cost of corrosion. So this thesis will focus on the corrosion behavior of 3D printing maraging steel. The purpose of this thesis was to find the best heat treatment condition for high corrosion resistance and to find the relationship between microstructure and corrosion behavior of maraging steel. In this thesis, several kinds of maraging steel samples with different heat treatment conditions were used. SLM, SLM austenized&amp;quenched, SLM aged, conventional austenized&amp;quenched, and conventional aged. Besides, two kinds of solutions were produced, NaOH (pH=11.5) and Na2SO4 (pH=6.5). To observe the microstructure, an optical microscope was used. The grain size is different between SLM and conventional samples, and also different between the samples with different heat treatment conditions. The potentiodynamic polarization method was used to measuring the corrosion behavior. SLM samples have much lower current density, and the passivation potential and the corrosion rate are similar compared with conventional samples. But due to the lack of further experiments, the relationship between corrosion behavior could be affected by the combined effect of several factors.
167

Value flow mapping of the material flow at Proton Finishing ALSAB`s warehouse / Värdeflödeskartläggning av materialflödet hos Proton Finishing ALSABs lager

Martinelle, Izabell, Nordstrand, Lisa January 2023 (has links)
Proton Finishing ALSAB (hereinafter referred to as ALSAB) is a company located in Anderstorp and active in surface treatment and powder coating. ALSAB is part of the Proton Finishing group and was acquired in 2020 and is therefore the newest facility of their total of five facilities. ALSAB varnishes products that their customers deliver, and they do not produce any products themselves. What makes ALSAB unique is that they can handle products that are up to five meters long, and that they can offer a wide range of colors for their powder coating. The study at ALSAB intends to improve their internal material flow inside the warehouse. At the moment, there is no clear routine for the material flow, and ALSAB is therefore asking for suggestions for improvement, ALSAB also need help with identification and elimination of non-value-adding activities, which they suspect exist within the material flow.  In order to identify any problems in Proton Finishing ALSAB's material flow, observations, interviews, document collection, process mapping and value flow mapping have been done. The observations made have been made by studying the material flow on site at Proton Finishing ALSAB, to see where activities occur that impair the smoothness of the material flow. Three employees within ALSAB have been interviewed during this study, where all three have different roles within the company in order to get several different perspectives on how the employees consider the material flow to work. Document collection was done through Proton Finishing ALSAB's business system – Jeeves. The data was collected on the number of products and pallets that were delivered and shipped each day, which is information that contributed to finding a connection between when and how many products ALSAB receives over the course of a year. The process mapping was developed to identify the process steps that were relevant for the value flow mapping. A value flow mapping was made of the activities that take place in the warehouse. The value flow mapping has contributed to showing which activities take up the most time, as well as which activities have the greatest variation in time.  The results show that the two activities that take the longest and vary the most in time are activities 2 and 4, which are arrival control and packing. The arrival control activity is when the arriving goods are checked so that they match what the delivery note states. The packing activity consists of three different steps: insulation, packing of goods and strapping. The three steps together make up the entire packing activity. The result also shows that the waiting times, in the value flow mapping illustrated with a triangle, which take up the most time are waiting time 1 and 5. These triangles represent the time that the products are stored in the in-storage, respectively the out-storage, as well as the time it takes to transport the products back and forth to the trucks. Based on this information several improvement proposals regarding a more leveled material flow inside Proton Finishing ALSAB's warehouse have been developed.  The improvement proposals that have been developed to make Proton Finishing ALSAB's material flow smoother varies in extent in terms of what the improvement would cost, as well as how long it would take to implement the various improvements. In the short term, several improvement proposals have been identified, including a new structure for the storage of the odd products, a larger doorway between warehouse and production, as well as purchasing another banding machine. In the long term, it is proposed to reposition where the different areas of the warehouse are located and also to build one more gate for shipping and deliveries. / <p>Examensarbetet är utfört vid Institutionen för teknik och naturvetenskap (ITN) vid Tekniska fakulteten, Linköpings universitet</p>
168

Effects of Dietary Lysine on Muscle Gene Expression and Fatty Acid Profiles and on Selected Carcass Characteristics and Plasma Hormone Concentrations in Late-Stage Finishing Pigs

Wang, Taiji 12 August 2016 (has links)
Dietary inclusion of sufficient lysine is very critical for optimizing pig’s growth performance. The objectives of this project were to study the effects of dietary lysine at different concentrations on (1) the growth performance and carcass characteristics, (2) the muscle gene expression profile and the possible alterations to the metabolic and signaling pathways, (3) the muscle fatty acid profile, and (4) the plasma concentrations of growth-related hormones of late-stage finishing pigs. Nine crossbred barrows were assigned to 3 dietary treatments (lysine-deficient, equate, and -excess diets) according to a completely randomized experimental design. During the 5-week feeding trial, pigs were allowed ad libitum access to experimental diets and water. All pigs and experimental diets were weighed individually each week during feeding trial to determine growth performance. After harvest, the carcass characteristics were determined and muscle samples were collected from longissimus dorsi for mRNA and fatty acid profiling, while the jugular vein blood was collected at the end of four weeks for analyses of three growth-related hormones. While the average daily gain showed a quadratic relationship, the dressing percentage and total lean cut weight both increased linearly with dietary lysine concentrations. Results of muscle gene expression data showed that dietary lysine deficiency may lead to decreased protein synthesis, increased protein degradation and lipid accumulation, while dietary lysine excess may lead to decreased protein degradation and increased lipid biosynthesis. Fatty acid (FA) composition data showed that different dietary lysine concentrations altered the intramuscular fat (IMF) content and FA composition, especially the unsaturated FAs. In particular, dietary lysine deficiency increased the IMF content and the proportion of mono-unsaturated FAs. Hormone analyses showed that the plasma concentrations of insulin and growth hormone were not affected by dietary lysine, whereas the concentration of insulin-like growth factor 1 was decreased by either dietary lysine deficiency or excess. Collectively, lysine may function as a signaling molecule to regulate the expression of genes related to protein turnover and lipid metabolism in the muscle of finishing pigs, causing differences in growth performance, carcass characteristics, and FA composition. IGF-1 may be a controlling growth factor that is sensitive to dietary lysine.
169

Compliant Motion Programming for Robust Robotic Surface Finishing

Buckmaster, David J. January 2009 (has links)
No description available.
170

Copper Wire-Bonding Reliability: Mechanism and Prevention of Galvanic Aluminum Bond Pad Corrosion in Acidic Chloride Environments

Asokan, Muthappan 05 1900 (has links)
With the reliability requirements of automobile microelectronics pushing towards near 0 ppb levels of failure control, halide induced corrosion issues in wire bonded devices have to be tightly controlled to achieve such a high reliability goal. With real-time corrosion monitoring, for the first time we demonstrated that the explosive H2 evolution coupled with the oxygen reduction reaction, occurring at the critical Al/Cu interfaces, is the key driving force for the observed aggressive corrosion. Several types of passivation coating on Cu wire surfaces to effectively block the cathodic H2 evolution were explored with an aim to disrupt this explosive corrosion cycle. The properties of the protective coating were evaluated using various analytical techniques. The surface coating exhibited high thermal stability up to 260 °C (evaluated using TGA analysis). A uniform, highly hydrophobic coating (surface contact angle of >130° with water), was achieved by carefully controlling CVD parameters such as time of deposition, surface control of Cu metal, amount of inhibitor compound loading, temperature of coating process etc. FTIR spectroscopy combined with corrosion screening was used to optimize the CVD passivated coating with strong chemisorption. SEM and EDX, XPS were carried out on various coated surfaces to understand the composition and selectivity of the film formed through this surface treatment. The surface selective nature of this coating (towards Cu) proved helpful in preventing potential delamination issues during epoxy molding process. The corrosion testing was carried out via HAST testing at 130°C, 2 atm pressure and 100% RH for 48 hours. Delamination analysis and continuity test showed that the inhibitor compound was able to effectively prevent the corrosion even after exposure to harsh HAST conditions.

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