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This thesis is focused on machining of thermal spray coatings. Particularly on testing of machining parameters and their influence on different types of abradable coatings used in the aerospace industry. The aim of research work is to test the parameters, measure cutting forces by using a dynamometer and their impact on the quality of the machined surface. Determination of the optimal machining parameters for different types of coatings based on results of measurements and the evaluation of surface quality. There are also presented techniques of thermal spray application and methods of coating evaluation. Further it describes a method of measuring cutting forces by using the dynamometer and methods of surface quality evaluation.

<p>  </p> <p>In commercial settings, piglet weaning and transportation occur concurrently due to the expansive application of multi-site production systems across the United States and the combination of these events can be defined as an early life stressor. Early life stress is known to reduce pig performance, efficiency, and immune resilience contributing to reduced welfare and increased production losses. To combat the deleterious effects of stress on pigs, the essential amino acid tryptophan (Trp) supplemented above current National Research Council (NRC 2012) recommended levels, improves neuroendocrine responses to stress, lowers plasma cortisol and norepinephrine concentrations, and improves hypothalamic-pituitary-adrenal axis recovery time following stress. However, there are discrepancies concerning the Trp requirement for nursery pigs, suggesting the 2012 recommendations for Trp may be inaccurate for optimizing growth performance and health in modern pigs. Three experiments were conducted to determine the effects of supplemented standard ileal digestible Trp above NRC (2012) recommended levels on performance, feed efficiency, immune vigor, and stress tolerance. The objective of experiment 1 was to eliminate or reduce short- and long-term, transport-induced reductions in piglet feed efficiency and growth by supplementing Trp above NRC (2012) recommendations pre-weaning and/or during the nursery phase. An oral gavage of Trp or a control milk carrier was provided to pre-allotted piglets beginning at day 5 of lactation and continuing to weaning. At weaning all pigs were blocked by sex, weaning weight and pre-wean treatment and randomly assigned to transport and post-wean treatments. Pigs were fed in four nursery phases with diets containing 1X or 2X NRC recommended concentrations of SID Trp and a common grower diet fed in 6 phases during the grow-finish period. At market, loin characteristics were measured via ultrasound and carcass data was collected from the packing plant. Pre-weaning Trp supplementation had no effect on pre-weaning growth performance; however, post-wean Trp increased overall body weight and average daily gain in nursery pigs when Trp was supplemented pre-wean. The objective for experiment 2 was to mitigate the adverse effects of early life transport stress on subsequent immune challenges by providing supplemental Trp during the nursery period. At weaning, pigs were transported for 8 hours and assigned to treatments of vaccine-induced immune challenge and dietary treatment. Pigs were fed standard nursery diets, in four phases, over 35 days with pigs receiving 1X or 2X the NRC (2012) recommended Trp concentration. Half the pigs on each dietary treatment were subjected to a 3-wk vaccine challenge consisting of circovirus, mycoplasma, and influenza vaccines administered in wk 2, 3, and 4 post-wean, respectively. At market, loin characteristics were measured via ultrasound and carcass data was collected.  At the culmination of the nursery period, unchallenged pigs supplemented with Trp were heavier compared to control pigs. This resulted from an overall improvement in average daily gain for 2X Trp fed pigs. However, increasing Trp did not affect market weight, loin eye area, or lean percent in market pigs, although 2X Trp increased back fat. The objective of experiment 3 was to determine what ratio of SID tryptophan, relative to lysine, maximizes growth performance and feed efficiency in weaned pigs during the nursery period. Pigs were blocked by sex and weaning weight and randomly allotted to one of five dietary treatments with Trp increasing stepwise by 0.33%-units, respectively. Pigs were fed standard nursery diets, in four phases, over 35 days with pigs receiving 1X, 1.33X, 1.66X, 2X, or 2.33X the NRC (2012) recommended Trp concentration.  Overall, there were no differences in performance or efficiency across dietary treatments during a 35-day nursery period in unstressed healthy pigs.  In conclusion, increasing Trp in swine diets prior to and/or following stress events can mitigate stress-related perturbations in performance and efficiency.      </p>

Die funktionsorientierte Messtechnik ist gegenwärtig für die Optimierung von Herstellung und Endbearbeitung thermisch gespritzter, tribologisch belasteter Kontakte unterrepräsentiert. Obwohl sich das Leitmotiv „Messen, Analysieren und Verbessern“ wie ein roter Fa-den durch gängige Standards (ISO/TS 16949, VDA 6.1, …) zieht, werden kaum effektive Verbesserungspotenziale identifiziert und industriell umgesetzt. In der Praxis wird vor allem die Stückzahl von fehlerbehafteten Teilen mittels statistischer Methoden gesteuert und geregelt (IPC 9199/DGQ-Band 16). Werden Fehlerzustandspopulationen in Softwaresystemen auf solche Weise identifiziert, verifiziert und mitigiert, so spricht man gem. IEC 62304 von Black-Box-Testing. Solange der Ertrag stimmt, steht die Zahl nicht zurückweisbarer Güter im Vordergrund und nicht, ob die Ereignisse im Produktentstehungsprozess beherrschten Regeln folgen. Im Gegensatz hierzu steht das sog. White-Box-Testing. Es bietet die Möglichkeit, Qualität nach DIN 55350 Teil 11 (sowie DIN ISO 9126) entlang aller Hilfs-, Stütz-, Wertschöpfungs- und Nutzungsvorgängen der Produkte konsistent zu behandeln. Das White-Box-Testing wird in der Fertigung von tribologischen Kontakten jedoch bisher nicht angewendet. In der vorliegenden Arbeit wird aufgezeigt, warum dieser Ansatz bei erstmaliger Implementierung zwar aufwändiger, umfassender Analysen bedarf, über das veränderte Leitmotiv im Gesamten jedoch die Erfolgsaussichten von Optimierungsinitiativen steigert. „Wie etwas Positives funktioniert“ wird dabei alternativ zur Frage, „wie etwas Schlechtes“ zu verhindern ist, behandelt. Über die Methodik hinaus werden konkrete Werk-zeuge vorgeschlagen, funktionsorientierte Konformitätszustände über den Fingerabdruck der Werkstoffbelastung zu identifizieren, in smarten und vernetzten Mess- und Prüfketten zu überwachen, zu regeln sowie mittels Leistungskennzahlen zu beurteilen.:1 EINLEITUNG UND MOTIVATION 1.1 Ausgangsituation 1.2 Allgemeine Bewertungskriterien der Zylinderlaufbahn 1.3 Beurteilungsformen fertigungstechnischer Aspekte 1.3.1 Verfahrensbeurteilung der Endbearbeitung und Herstellung 1.3.2 Beurteilung von Verfahrensanwendungen unter Gesichtspunkten industrieller Messtechnik 1.4 Zusamenfassung und Rezension existierender Konzepte zur Qualitätssicherung der technischen Oberfläche 2 FORSCHUNGSBEDARF UND THEMATISCHE EINGRENZUNG 2.1 Bestimmung des Untersuchungsgegenstandes 2.2 Problemstellung Anomalien thermisch gespritzter Zylinderlaufflächen in Serie und Vorserie 2.2.1 Konsekutive Phänomene der Materialauftragungen sowie Mikrofresser in motorischer Belastung und vorheriger Endbearbeitung 2.2.2 Beeinflusste Materialparameter durch Endbearbeitung und Auswirkungen auf die Laufstabilität/ Fressneigung 2.2.3 Limitierung in der Anwendung und Deutung genormter Parameter industrieller Oberflächenmesstechnik 2.3 Hypothesen und theoretischer Ansatz 2.4 White-Box-Ansatz zur funktionsorientierten Herstellung und Endbearbeitung 3 UMFELDANALYSE ZUR METHODENENTWICKLUNG 3.1 Einordnung existierender theoretischer Modelle und Konzepte 3.2 Tribologische Systemgrößen Zylinderlaufbahn im Betrieb und während der Endbearbeitung 3.2.1 Reibungsszustände 3.2.2 Verschleißmechanismen und -kenngrößen 3.2.3 Schmierung 3.2.4 Nutz- und Verlustgrößen, Tribologische Prüfungen 3.3 Gegenwärtige Gestaltung und Ausführung der Zylinderlaufbahn 3.3.1 Zylinderlaufbahnkonzepte 3.3.2 Einfluss moderner Konzepte der Kolbengruppe und der Schmierung 3.3.3 Topographie und abgeleitete Endbearbeitungskonzepte 3.3.4 Honen von Zylinderbohrungen 3.4 Tribologie der Endbearbeitung als Schlüssel zu funktionsgerechten Oberflächen 3.4.1 Abtragsvorgänge beim Honen und Superfinishen 3.4.2 Oberflächenanalytik zur Beschreibung von Abtragsmechanismen 3.4.3 Kraftdynamik in der Endbearbeitung 3.4.4 Kombinierte Technologie: Sensitives-adaptives Honen und Superfinishen 3.5 Thermisches Spritzen von Zylinderlaufflächen 3.5.1 Vorgänge des Werkstoffauftrags im Zuge des Thermischen Spritzens 3.5.2 Lichtbogendrahtspritzen, LDS 3.5.3 Zerstäubung und Spritzstrahlausprägung 3.5.4 Auftreffen und Erstarrung der Spritzpartikel im Schichtverbund 3.6 Werkstoffintegrität der LDS-Spritzschicht 4 ABLEITUNG UND FESTLEGUNG FUNKTIONSRICHTIGER MESSSTRATEGIE 4.1 Begründung und Verwertung des White-Box-Testing-Ansatzes 4.2 Werkstoffparameter funktionaler Oberflächen 4.2.1 Struktureigenschaften und Festigkeit 4.2.2 Physikalische und chemische Eigenschaften 4.3 Technische Oberfläche, lang- und kurzwellige Gestaltabweichungen 4.3.1 Skalenabhängige, geometrische Kontaktbedingungen 4.3.2 Meso- und Mikrokontakt der Zylinderlauffläche 4.4 Operationalisierung der Testhypothese 5 NUTZUNG MESSTECHNISCH RÜCKFÜHRBARER WECHSELWIRKUNGEN FÜR HERSTELLUNG UND ENDBEARBEITUNG 5.1 Funktionsorientierte, definierte Variation lokalisierter Fertigungsmerkmale 5.1.1 Endbearbeitung der Spritzschicht 5.1.2 Herstellung der Spritzschicht 5.1.3 Spezifikation und Verifikation varianter Merkmale der Laufbahn 5.2 Versuchseinrichtung und -bauteile zur Methodenentwicklung 5.2.1 Ausführung im Sinne des White-Box-Testings 5.2.2 Flachproben 5.2.3 Zylinder 6 ANWENDUNG FUNKTIONSORIENTIERTER WERKZEUGE IM QUALITÄTSREGELKREIS 6.1 Verifikationsstrategie 6.2 Spezifische Merkmale der Werkstoffbelastung in Fertigung und Tribometrie 6.3 Fehlerinduktion, -Verifikation und -Behandlungsroutine im geschlossenen Qualitätsregelkreis 6.3.1 Charakterisierung zuordbarer Zylinderlaufbahnperformanceabweichungen 6.3.2 Rückverfolgbare Messkette von tribologischer Belastung über die Endbearbeitung bis zur Herstellung 6.3.3 Werkstoffintegrität als Einflussgröße in der Endbearbeitung und Tribometrie 6.4 Ermittlung von Leistungskennzahlen während der Fertigung mit Auswirkung auf das Verhalten bei tribologischer Prüfung zur Qualitätsregelung 7 ZUSAMMENFASSUNG UND FAZIT 8 LITERATURVERZEICHNIS 9 VERZEICHNIS DER ABBILDUNGEN UND TABELLEN 10 ANHANG 10.1 Messtechnische Grundlagen, Stichwortverzeichnis 10.2 Oberflächenunvollkommenheiten nach DIN EN ISO 8785 10.3 Weiterführende Ergebnisse der Analyse von Oberflächenunvollkommenheiten 10.4 Ausgewählte Ergebnisse im Zuge der Zusammenarbeit und Veröffentlichung Hick et al. 2018 [336] (nicht in der Form veröffentlichtes Material) / Function-oriented measurement technology is currently underestimated when it comes to optimizing layer production and finishing of thermally sprayed, tribologically stressed contacts. Although the fundamental premise 'measure, analyse and improve' runs like a common thread through all the common standards (ISO/TS 16949, VDA 6.1, ...), hardly any effective improvement potentials are identified and realized with industrial profit. In today’s industrial applications, the number of defective parts is controlled and regulated using conventional statistical methods (IPC 9199/DGQ Volume 16). This is a so-called “black box testing” according to IEC 62304 when used at error management in software applications for identifaction, verification and mitigation. Finally, quantitative production output is focussed and not the inner operating system’s processes of the manufacturing system or interdependencies at product use. Opposite to this, the so-called “white box testing” alternatively focuses on the inner functioning of the processes and the quality of its results according to DIN 55350 Part 11 (as well as DIN ISO 9126) at each value-added process from production to product use on an equal footing. While this approach is more elaborate and demanding because of wide-ranging analysis, in the presented work it is demonstrated why it is more promising at holistic optimisations efforts in terms of the leitmotiv with the question 'how something positive works' versus the more conventional defensive recognized question 'how something bad can be prevented'. However, white box testing has not yet been used in manufacturing of tribological contacts. In addition to the methodology, concrete tools are proposed to identify function-oriented states of conformity via the fingerprint of the material load, to monitor and regulate them in smart, networked measurement and test chains using suitable performance indicators.:1 EINLEITUNG UND MOTIVATION 1.1 Ausgangsituation 1.2 Allgemeine Bewertungskriterien der Zylinderlaufbahn 1.3 Beurteilungsformen fertigungstechnischer Aspekte 1.3.1 Verfahrensbeurteilung der Endbearbeitung und Herstellung 1.3.2 Beurteilung von Verfahrensanwendungen unter Gesichtspunkten industrieller Messtechnik 1.4 Zusamenfassung und Rezension existierender Konzepte zur Qualitätssicherung der technischen Oberfläche 2 FORSCHUNGSBEDARF UND THEMATISCHE EINGRENZUNG 2.1 Bestimmung des Untersuchungsgegenstandes 2.2 Problemstellung Anomalien thermisch gespritzter Zylinderlaufflächen in Serie und Vorserie 2.2.1 Konsekutive Phänomene der Materialauftragungen sowie Mikrofresser in motorischer Belastung und vorheriger Endbearbeitung 2.2.2 Beeinflusste Materialparameter durch Endbearbeitung und Auswirkungen auf die Laufstabilität/ Fressneigung 2.2.3 Limitierung in der Anwendung und Deutung genormter Parameter industrieller Oberflächenmesstechnik 2.3 Hypothesen und theoretischer Ansatz 2.4 White-Box-Ansatz zur funktionsorientierten Herstellung und Endbearbeitung 3 UMFELDANALYSE ZUR METHODENENTWICKLUNG 3.1 Einordnung existierender theoretischer Modelle und Konzepte 3.2 Tribologische Systemgrößen Zylinderlaufbahn im Betrieb und während der Endbearbeitung 3.2.1 Reibungsszustände 3.2.2 Verschleißmechanismen und -kenngrößen 3.2.3 Schmierung 3.2.4 Nutz- und Verlustgrößen, Tribologische Prüfungen 3.3 Gegenwärtige Gestaltung und Ausführung der Zylinderlaufbahn 3.3.1 Zylinderlaufbahnkonzepte 3.3.2 Einfluss moderner Konzepte der Kolbengruppe und der Schmierung 3.3.3 Topographie und abgeleitete Endbearbeitungskonzepte 3.3.4 Honen von Zylinderbohrungen 3.4 Tribologie der Endbearbeitung als Schlüssel zu funktionsgerechten Oberflächen 3.4.1 Abtragsvorgänge beim Honen und Superfinishen 3.4.2 Oberflächenanalytik zur Beschreibung von Abtragsmechanismen 3.4.3 Kraftdynamik in der Endbearbeitung 3.4.4 Kombinierte Technologie: Sensitives-adaptives Honen und Superfinishen 3.5 Thermisches Spritzen von Zylinderlaufflächen 3.5.1 Vorgänge des Werkstoffauftrags im Zuge des Thermischen Spritzens 3.5.2 Lichtbogendrahtspritzen, LDS 3.5.3 Zerstäubung und Spritzstrahlausprägung 3.5.4 Auftreffen und Erstarrung der Spritzpartikel im Schichtverbund 3.6 Werkstoffintegrität der LDS-Spritzschicht 4 ABLEITUNG UND FESTLEGUNG FUNKTIONSRICHTIGER MESSSTRATEGIE 4.1 Begründung und Verwertung des White-Box-Testing-Ansatzes 4.2 Werkstoffparameter funktionaler Oberflächen 4.2.1 Struktureigenschaften und Festigkeit 4.2.2 Physikalische und chemische Eigenschaften 4.3 Technische Oberfläche, lang- und kurzwellige Gestaltabweichungen 4.3.1 Skalenabhängige, geometrische Kontaktbedingungen 4.3.2 Meso- und Mikrokontakt der Zylinderlauffläche 4.4 Operationalisierung der Testhypothese 5 NUTZUNG MESSTECHNISCH RÜCKFÜHRBARER WECHSELWIRKUNGEN FÜR HERSTELLUNG UND ENDBEARBEITUNG 5.1 Funktionsorientierte, definierte Variation lokalisierter Fertigungsmerkmale 5.1.1 Endbearbeitung der Spritzschicht 5.1.2 Herstellung der Spritzschicht 5.1.3 Spezifikation und Verifikation varianter Merkmale der Laufbahn 5.2 Versuchseinrichtung und -bauteile zur Methodenentwicklung 5.2.1 Ausführung im Sinne des White-Box-Testings 5.2.2 Flachproben 5.2.3 Zylinder 6 ANWENDUNG FUNKTIONSORIENTIERTER WERKZEUGE IM QUALITÄTSREGELKREIS 6.1 Verifikationsstrategie 6.2 Spezifische Merkmale der Werkstoffbelastung in Fertigung und Tribometrie 6.3 Fehlerinduktion, -Verifikation und -Behandlungsroutine im geschlossenen Qualitätsregelkreis 6.3.1 Charakterisierung zuordbarer Zylinderlaufbahnperformanceabweichungen 6.3.2 Rückverfolgbare Messkette von tribologischer Belastung über die Endbearbeitung bis zur Herstellung 6.3.3 Werkstoffintegrität als Einflussgröße in der Endbearbeitung und Tribometrie 6.4 Ermittlung von Leistungskennzahlen während der Fertigung mit Auswirkung auf das Verhalten bei tribologischer Prüfung zur Qualitätsregelung 7 ZUSAMMENFASSUNG UND FAZIT 8 LITERATURVERZEICHNIS 9 VERZEICHNIS DER ABBILDUNGEN UND TABELLEN 10 ANHANG 10.1 Messtechnische Grundlagen, Stichwortverzeichnis 10.2 Oberflächenunvollkommenheiten nach DIN EN ISO 8785 10.3 Weiterführende Ergebnisse der Analyse von Oberflächenunvollkommenheiten 10.4 Ausgewählte Ergebnisse im Zuge der Zusammenarbeit und Veröffentlichung Hick et al. 2018 [336] (nicht in der Form veröffentlichtes Material)

In many cases, the functional performance of additively manufactured components can only be ensured by finishing the functional surfaces. Various methods are available for this purpose. This paper presents a procedure for selecting suitable processes for finishing laser beam melting additive–manufactured parts which is ultimately based on technological knowledge. It was experimentally proven that the use of several consecutive finishing processes is beneficial to achieve better surface quality. One finishing process chain was particularly effective (namely particle blasting/vibratory grinding/plasma electrolytic polishing) and the technological limits of this method were investigated in this study. The optimal parameters for this process combination ensured a surface roughness Sa < 1 µm.

Ultraprecision single point diamond turning is required to produce parts with sub-nanometer surface roughness and sub-micrometer surface profiles tolerances. These parts have applications in the optics industry, where tight form accuracy is required while achieving high surface finish quality. Generally, parts can be polished to achieve the desired finish, but then the form accuracy can easily be lost in the process rendering the part unusable. Currently, most mid to low spatial frequency surface finish errors are inspected offline. This is done by physically removing the workpiece from the machining fixture and mounting the part in a laser interferometer. This action introduces errors in itself through minute differences in the support conditions of the over constrained part on a machine as compared to the mounting conditions used for part measurement. Once removed, the fixture induced stresses and the part’s internal residual stresses relax and change the shape of the generally thin parts machined in these applications. Thereby, the offline inspection provides an erroneous description of the performance of the machine. This research explores the use of a single, high resolution, capacitance sensor to quickly and qualitatively measure the low to mid spatial frequencies on the workpiece surface, while it is mounted in a fixture on a standard ultraprecision single point diamond turning machine after a standard facing operation. Following initial testing, a strong qualitative correlation exists between the surface profiling on a standard offline system and this online measuring system. Despite environmental effects and the effects of the machine on the measurement system, the capacitive system with some modifications and awareness of its measurement method is a viable option for measuring mid to low spatial frequencies on a workpiece surface mounted on an ultraprecision machine with a resolution of 1nm with an error band of ±5nm with a 20kHz bandwidth. / Thesis / Master of Applied Science (MASc)

Products with complicated shapes require superior surface finish to perform the intended function. Despite significant developments in technology, finishing operations are still performed semi automatically/manually, relying on the skills of the machinist. The pressure to produce products at the best quality in the shortest lead time has made it highly inconvenient to depend on traditional methods. Thus, there is a rising need for automation which has become a resource to remain competitive in the manufacturing industry. Diminishing return of trading quality over time in finishing operations signifies the importance of having a pre-determined trajectory (tool path) that produces an optimum surface in the least possible machining time. Tool path optimization for finishing process considering tool kinematics is of relatively low importance in the present scenario. The available automation in grinding processes encompass around the dynamics of machining. In this paper we provide an overview of optimizing the tool path using evolutionary algorithms, considering the significance of process dynamics and kinematics. Process efficiency of the generated tool movements are studied based on the evaluation of relative importance of the finishing parameters. Surface quality is analysed using MATLAB and optimization is performed on account of peak to valley height. Surface removal characteristics are analysed based on process variables that have the most likely impact on surface finish. The research results indicated that tool path is the most significant parameter determining the surface quality of a finishing operation. The inter-dependency of parameters were also studied using Taguchi design of experiments. Possible combinations of various tool paths and tool influencing parameters are presented to realize a surface that exhibits lowest errors. / European Horizon 2020 Project SYMPLEXITY

Heat stress (HS) induced changes in energy metabolism, proteolysis, lipogenesis, and oxidative balance have meat quality ramifications for livestock. However, several knowledge gaps exist in understanding heat stressed finishing pig physiology and pork quality characteristics and how dietary zinc may ameliorate undesirable outcomes. Research was completed to determine zinc supplementation effects on carcass composition, meat quality, and oxidative stability of fresh and processed pork from pigs subjected to a chronic, cyclic heat stress using a 2×2×2 factorial arrangement of treatments with main effects of environment (HS vs. thermoneutral; TN), added zinc level (50 vs. 130 mg kg^-1 available zinc), and zinc source (inorganic vs. organic). Commercial crossbred mixed-sex pigs (initially 72.0 kg) were group-housed under either TN (18.9-16.7°C) or cycling HS conditions with chronic diurnal heat (30-29°C/26-27°C for 12h:12h) on days 24-71 with acute heat waves (32-33°C/29-30°C for 12h:12h) on days 21-24, 42-45, and 63-65. One representative pig (<i>n</i>=80) per pen was slaughtered on day 64. The HS pigs were lighter bodyweight (<i>P</i>=0.039), yielded lighter carcasses (<i>P</i>=0.011), less last rib backfat (<i>P</i>=0.032), tended to have smaller loin eye area (<i>P</i>=0.062) but similar percent lean in belly center slices (<i>P</i>>0.10). Compared to TN, HS carcasses had higher 24-h pH (<i>P</i>=0.001) and decreased drip loss (<i>P</i>=0.034). Shifts in individual fatty acid profile of sausage product derived from HS carcasses were observed but were of insufficient magnitude to affect iodine value. Initially, sausage from HS carcasses tended (day 0, <i>P</i>=0.071) to have less thiobarbituric acid reactive substances than TN but over a 10-day simulated retail display, no treatment induced lipid oxidation differences (<i>P</i>>0.05) were observed in either sausage or displayed loin chops. Consistent treatment differences in CIE L*a*b* of products throughout the 10-day display were not observed. The relationships between physiological changes in pigs receiving supplemental zinc and their body and ambient temperatures were also investigated. A representative gilt (<i>n</i>=96) was selected for thermal monitoring from each pen of the 2×2×2 treatments plus 4 additional treatments representing 2 intermediate levels of Zn in both environments. Core body temperatures (T_core) during the day 42-45 acute heat wave were continuously recorded via indwelling vaginal thermometers and infrared thermal imaging was used to measure skin temperatures at 12-hour intervals. From a 64-gilt subset of the 2×2×2 treatments, jejunum and ileum samples were collected on day 64 for analysis of villus height, crypt depth, and jejunal gene expression of heat shock proteins (27, 70, 90), occludin, and mucin (MUC2). The HS model induced thermoregulatory changes and increases in T_core (<i>P</i><0.05). Day 42-45 ambient temperature was negatively correlated with expression of HSP-27 (r=-0.42, <i>P</i>=0.047), HSP-90 (r=-0.49, <i>P</i>=0.014), and occludin (r=-0.69, <i>P</i><0.001) in HS pigs. For the organic Zn supplemented pigs, ambient temperature was positively correlated with expression of HSP-27 (r=0.42, <i>P</i>=0.034) and MUC2 (r=0.45, <i>P</i>=0.017) and negatively correlated with villus height in jejunum (r=-0.42, <i>P</i>=0.027) and ileum (r=-0.38, <i>P</i>=0.048). Thermal Circulation Index (measure of heat dissipation) of HS pigs was negatively correlated with their ileum villus height (r=-0.51, <i>P</i>=0.015) and positively correlated with HSP-70 expression (r=0.46, <i>P</i>=0.041). The T_core lacked correlation with most variables. This research demonstrates cyclic HS affects carcass composition and quality but does not appear to reduce display shelf-life of pork as indicated by lack of differences in lipid oxidation and color stability. In this HS model, zinc level or source imparted negligible benefits and thermal correlations with gut integrity characteristics existed for organic zinc supplemented and HS pigs. The degree of heat dissipation by heat stressed pigs appeared to be associated with classic HS damage and intestinal responses which may be useful indicators of HS in the grow-finish pig. Another agricultural challenge is maintaining higher education programming which establishes a successful career trajectory for agricultural students amid generational shifts in attitudes and background experiences. Undergraduates studying Animal Science and/or Agricultural Economics were surveyed to understand their perception of how collegiate curricular, co-curricular, and extracurricular experiences (coursework, club participation, relevant work experience, international experience, advising/mentoring, college life, and professional networking) contribute to their anticipated career success. A best-worst scaling experiment was used to force respondents (<i>n</i>=487) to make unbiased tradeoffs between the collegiate experience attributes. Responses were then related back to additional demographical and experience/perception characteristics of respondents. Students indicated relevant work experience was overwhelmingly the most critical of the 7 factors (57% preference share), followed by professional networking (19%), and coursework (14%). Students solely in a pre-veterinary Animal Science curriculum represented a distinct category of students regarding their beliefs and experiences. Further research is needed to investigate possible disconnects between student perceptions and reality in higher education and agricultural careers.

The use of pre-hardened mold steels has increased appreciably over the years; more than 80% of the plastic mold steels are used in pre-hardened condition. These steels are delivered to the customer in finished state i.e. there is no need of any post treatment. With hardness around ~40HRC, they have properties such as good polishability, good weldability, corrosion resistance and thermal conductivity. Machinability is a very important parameter in pre-hardened mold steels as it has a direct impact on the cost of the mold. In normal machining operations involving intricate or near net shapes, machining constitutes around 60% of the total mold cost. Efforts are underway to explore every possible way to reduce costs associated with machining and to make production more economical. All the possible parameters which are considered to affect the machinability are being investigated by the researchers. This thesis work focuses on the effect of prior austenite grain size on the machinability of pre-hardened mold steel (Uddeholm Nimax).  Austenitizing temperatures and holding times were varied to obtain varying grain sized microstructures in different samples of the same material. As it was difficult to delineate prior-austenite grain boundaries, experimental and empirical methods were employed to obtain reference values. These different grain sized samples were thereafter subjected to machining tests, using two sets of cutting parameters. Maximum flank wear depth=0.2mm was defined for one series of test which were more akin to rough machining, and machining length of 43200mm or maximum wear depth=0.2mm were defined for second series of tests which were similar to finishing machining. The results were obtained after careful quantative and qualitative analysis of cutting tools. The results obtained for Uddeholm Nimax seemed to indicate that larger grain sized material was easier to machine. However, factors such as retained austenite content and work hardening on machined surface, which lead to degradation of machining operations were also taken into consideration. Uddeholm Nimax showed better machinability in large grained samples as retained austenite(less than 2%) content was minimal in the large grained sample. Small grained sample in Uddeholm Nimax had a higher retained austenite (7+2%) which resulted in degradation of machining operation and a lesser cutting tool life.