Mechanical unloading has deleterious effects on the musculoskeletal system and results in significant reductions in bone density, mass, and strength, which do not fully recover even years after returning to weightbearing. For example, the rate of bone loss in microgravity is 10-fold more rapid than the rate of loss seen in elderly Caucasian females, the population group most predisposed to osteoporosis. This raises concern with individuals who are exposed to multiple bed rest periods or crewmembers who make repeated missions. Exercise offers a way to reduce or reverse these effects. Dual-energy X-ray absorptiometry (DXA) densitometry and bone mineral density (BMD) alone are generally insufficient for capturing the complex changes in bone mass, structure, and integrity and not an accurate predictor of fracture risk. Therefore, it is essential to measure the mechanical properties of bone tissue directly using animal models. The hindlimb unloaded (HU) rat model is a well-established ground-based analog for studying bone response to disuse and effects of spaceflight. The current study is one of the very few that has measured longitudinally densitometric and mechanical properties of bone after repeated simulated microgravity and long-term recovery at multiple anatomic sites in skeletally mature rats. The specific aims were to characterize 1) loss and recovery dynamics of bone following a period of unloading, 2) bone response after a second exposure to 28 days of HU, following an initial 28 days of HU and a recovery period equal to twice the duration of initial exposure, and 3) effects of resistance exercise during recovery period following an initial HU exposure and its effects on a subsequent exposure. In general, our data showed that bone response to unloading and recovery is site-specific. More specifically, we found that: 1) the rat proximal tibia metaphysis modeled the loss and discordant recovery dynamics as seen in the International Space Station (ISS) crewmembers proximal femur better than the rat femoral neck; 2) the initial exposure to HU has minimal effect on the subsequent HU exposure, and detrimental effects of the second HU exposure were milder than the initial due to reduced mechanosensitivity of the bone; 3) exercise significantly enhanced recovery following the initial HU exposure, and losses during the second exposure were not affected by exercise in most cases.

Storage of granular solids in silos has been the practice for many years. Engineers have been faced with the problem of making the silos empty more efficiently and minimising the forces acting on the walls of the silo during material discharge. To this end the anti-dynamic tube was invented. The tube has a smaller diameter than the silo and consists of several portholes along its height and around its circumference. When the discharge gate of the silo is opened the granular material enters the tube through the portholes, flows down the inside of the tube and exits the silo through the discharge gate. Most tubes have been installed such that there was sufficient space between the base of the tube and silo bottom for the granular material to flow simultaneously through the discharge gate. The flowing material causes a down drag on the tube from the friction of the granular material on the walls of the tube. Previous research has underestimated the magnitude of these frictional forces resulting in catastrophic buckling failure of the tubes, blocking the discharge gate of the silo. A blockage of the discharge gate requires top emptying of the silo resulting in financial losses and down time of equipment. A steel model silo with an anti-dynamic tube was set up in the laboratory to measure the friction on the tube during material flow. From the results of these experiments, an equation has been derived to estimate the magnitude of the down-drag force. Furthermore, an empirical expression was developed for the effects of the speed of the flowing material on the magnitude of the down-drag force. To keep construction costs down, it is necessary to optimise the wall thickness of the tube. There is currently no theory for the buckling capacity of a thin walled cylindrical shell with multiple perforations around its height and circumference. Therefore additional experiments were undertaken on a cylindrical shell with multiple perforations subjected to a combination of an axial as well as an external lateral pressure. Following on from the experiments, finite element analyses were undertaken to compare with the experimental results. For each finite element analysis an out-of-roundness was introduced as an initial wall imperfection. From these analyses and the cylinder experiments, a method of producing interaction curves for tubes with varying ratios of open area has been developed.

Thesis (Ph.D.)--University of Western Australia, 2003.

Kostnaderna för byggnadsprojekt ökar varje år, detta beror på ett flertal faktorer såsom nya standarder, synen på att bygga miljövänligt samt hårdare krav från byggherrar som vill få projekten klara på kortare tid. För att kunna möta kraven måste byggföretagen hitta nya sätt för att bygga mer effektivt och lönsamt. Ett område med potential för utveckling är logistiken runt om och på arbetsplatsen. Arbetet utgår från bygglogistik, mer specifikt materialhantering samt lossning på arbetsplatsen. Studien har utförts på två olika byggarbetsplatser i Linköping för att kunna analysera likheter och skillnader mellan arbetsplatserna då de har olika förutsättningar. Studien undersöker och belyser de mest kritiska momenten på arbetsplatserna, identifierar hur problemen uppstår och möjliga lösningar till dessa. Data som studien bygger på har samlats in genom intervjuer och observationer. Studien visar på att en stor del utav de problemen som observerades hade kopplingar till planeringen i form utav APD-planer, bristfällig kommunikation samt platsbrist på bygget.

The aim of the diploma thesis is the analysis of driver responsibility during the loading and unloading of the goods at HOPI, the characteristics of the complaints grounds for the selected partner and the presentation of one type of complaints with a proposal to solve how to prevent further damage to the goods. The first part analyzes the responsibility of the carrier, where distinguishes several types of liability including the extent of liability for loss, damage or destruction of the consignment. The practical part describes the work and responsibility of the driver at HOPI. The reasons for Savencia's complaints are characterized, and the last part of the thesis concerns with one reason of complaint (damage of goods) and then proposes a solution.

The problems with the crack length determination by the unloading compliance method are well known for Charpy size specimens. The final crack lengths calculated for bent specimens do not fulfil ASTM 1820 accuracy requirements. Therefore some investigations have been performed to resolve this problem. In those studies it was considered that measured compliance should be corrected for various factors, but satisfying results were not attained. In the presented work the problem was attacked from the other side, the measured specimen compliance was taken as a correct value and what had to be adjusted was the calculation procedure. On the basis of experimentally obtained compliances of bent specimens and optically measured crack lengths the investigation was carried out. Finally, a calculation procedure enabling accurate crack length calculation up to 5mm of plastic deflection was developed. Applying the new procedure, out of investigated 238 measured crack lengths, more than 80% of the values fulfilled the ASTM 1820 accuracy requirements, while presently used procedure provided only about 30% of valid results. The newly proposed procedure can be also prospectively used in modified form for the specimens of different than Charpy size.

Studies of the microstructure of tendon-bone attachments in mammals have shed light on their role in mediating efficient force transfer between tendon and bone, two tissues that differ vastly in their structure, composition, and material properties. Studies have also elucidated the importance of mechanical stimulation in maintaining tendon-bone attachment structures so that they may function successfully in dissipating mechanical stresses at the tendon-bone interface, to minimize the risk of tissue failure. Gross anatomical studies in fish have focused on identifying pathways of myomere contractile force transmission to the backbone of the fish, via connective tissue septa, to achieve body undulation. Little focus has been placed on how these connective tissues connect to the bone at the microscopic level to achieve force transfer. Moreover, whether or not these attachments are capable of undergoing remodeling in response to novel force regimes—which may influence their function—remains to be elucidated. First, we characterized the microstructure and material properties of the epicentral tendon-vertebra attachment in rainbow trout by conducting histology and tensile-testing. Individual collagen fibers of the epicentral tendon projected directly into the cancellous bone of the vertebra. We observed rostral-to-caudal trends in material properties for attachments found at different positions within the region spanning the dorsal and adipose fin, suggesting that attachments differed in their structure and/or composition at different positions along the backbone. Furthermore, the angle of the epicentral tendon with respect to the bone influenced the material properties and structural integrity of the attachments during tensile-testing, suggesting that attachments may be optimized to transfer force along particular angles. Second, we studied the effect of unloading on the material properties of the epicentral tendon-vertebra attachment by severing a subset of epicentral tendons on one side of rainbow trout. Severing of epicentral tendons had no effect on attachment material properties, suggesting that attachments did not undergo any alterations in structure and/or composition. We propose that the contiguous network of connective tissues in which the epicentral tendons are embedded as well as the fish’s gross musculature may have supported the maintenance of function of the epicentral tendon-vertebra attachments.

This report presents the result of a Master thesis course done at the Machine Design department at KTH. The thesis was written at the company Svea Teknik in collaboration with the tunnel boring machine manufacturer Atlas Copco. The high longitudinal force needed when the Remote Vein Miner is boring is achieved by the friction when clamping the machine between the tunnels ceiling and ground using hydraulic cylinders mounted on the top and bottom of the machine. A new generation of machines doesn’t allow for the bottom cylinders to be fitted on the machine. The pair of continuous tracks used to propel the machine must bear these loads but the tracks aren’t strong enough to alone support the weight of the boring machine. This creates the need for an unloading system which unloads the inner wheels of the track so they don’t fail. Concepts were generated using a morphological matrix with the load sharing unit broken down to sub functions with several solutions paired to each. The iterative process led to nine concepts, where two proved more promising than the others when they were subjected to a Pugh’s evaluation matrix. The two concepts were developed further where a feasibility analysis indicated that only one concept was feasible with the dimensions given in a CAD model together with the load provided by Atlas Copco. The remaining concept is based on hydraulic cylinders lifting the inner wheels of the track to unload them while the machine is boring. The machine is then resting on a skid mounted inside the track. A CAD model was made of the new concept and the new components strength was analyzed using FEM-models. / I denna uppsats presenteras resultatet av ett examensarbete för masterprogrammet Maskinkonstruktion på KTH. Arbetet utfördes på förtaget Svea Teknik tillsammans med tunnelborrmaskintillverkaren Atlas Copco. De stora longitudinella krafterna som krävs när tunnelborrmaskiner borrar erhålls med hjälp av hydraulcylindrar monterade både på ovan- och undersidan av maskinen som klämmer fast maskinen mellan tunnelns golv och tak. En ny generation maskiner från Atlas Copco tillåter inte hydraulcylindrar monterade framtill på undersidan av maskinen. Istället tar de båda bandenheterna som är avsedd att driva maskinen framåt upp dessa krafter. Bandenheterna är inte tillräckligt starka för dessa laster utan en avlastningslösning för hjulen inne i bandenheten behövs. Problemet delades upp i subfunktioner som sattes in i en morfologisk matris för att generera koncept. Den iterativa processen ledde till nio koncept där två av dem visades mest lovade efter en konceptutvärdering med hjälp av en Pugh’s matris. De båda koncepten arbetades vidare till en mer detaljerad nivå där en rimlighetsanalys visade att endast ett koncept var fysiskt möjligt att applicera med de givna begräsningarna som gavs av utrymmet i den givna CAD-modellen tillsammans med de givna lasterna. Det kvarstående konceptet baseras på hydrauliska kolvar som monteras på hjulen i bandenheten. Dessa förflyttar hjulen uppåt tills de inte är i kontakt med bandenhetens kedja längre. Kedjan vilar då på en stödstruktur som är stark nog för lasterna. En CAD-modell gjordes på konceptet och de nya komponenternas hållfasthet analyserades med hjälp av FEM-modeller.

För att arbetsledaren skall utveckla en logistikorganisation som fungerar mer än väl bygger detta alltid på att de interna logistikrutinerna är välfungerande. Rutinerna skall fungera om riktlinjer och stöd för arbetsledaren i alla typer av projekt. Studien syftar att studera NCC-projekt som använder och/eller inte använder det nya verktyget, lossningskalender, för att identifiera dess positiva resultat Studien använder en kvalitativ metod där författaren genomför intervjuer med 4 respondenter inom NCC. Resultatdelen består av tre kategorier efter bearbetning av insamlade data, dessa är: Effektivisering, Dokumentering och Stöd för arbetsledning. Elektroniska logistikverktyg som lossningskalendern är av stor betydelse för arbetsledaren och kan vara avgörande i kvalitén i samtliga byggprojekt. / Logistics has long been a topic for discussion that has recently gained more attention. In order for the supervisor to develop a logistics organization that works more than well, this always means that the internal logistics routines are well functioning. The procedures should work on guidelines and support for the supervisor in all types of projects. The study aims to study NCC-projects that use and / or do not use the new tool, release calendar, to identify its positive results. The study uses a qualitative method in which the author conducts interviews with 4 respondents within NCC. The result consists of three main categories processing collected data, these categories are: Efficiency, documentation and Support for work management. Electronic logistics tools like the unloading calendar are of great importance to the supervisor and can be decisive in the quality of all construction projects.

Neste trabalho os resultados da metodologia de normalização de E. D. Reese e K. H. Schwalbe para a obtenção de curvas J-R, são comparadas com aquelas obtidas pela tradicional Técnica de Variação de Flexibilidade Elástica. Ambos os métodos foram aplicados à um aço de grau nuclear A508-CL3A, quando vários corpos-de-prova miniaturizados 0.394TC[S], foram testados em temperaturas típicas de operação de vasos de pressão nuclear. Corpos-de-prova miniaturizados formam tratados termicamente tentando simular o comportamento exibido pelos aços estruturais quando submetidos à diferentes níveis de exposição de nêutrons, sendo que outros foram ensaiados na condição de como-recebidos. Todos os procedimentos experimentais e analíticos empregados neste estudo foram totalmente computadorizados, incluindo aquisição e refinamento dos dados e o traçado da curva J-R. Esta última foi realizada conforme a mais recente versão das normas ASTM, denominada ASTM-E1820. As variáveis avaliadas influentes do comportamento das curvas de J-R, incluem o incremento de propagação de trinca e o número de pontos de dados de carga versus deslocamento. Também foi analisada a efetividade do método de normalização quando comparada com a técnica de variação de flexibilidade elástica. Os resultados desta pesquisa mostraram que a normalização é uma metodologia confiável e muito simples, tão logo a programação de software seja desenvolvida, para ser aplicada em uma vasta variação de comportamentos mecânicos como amostrados neste estudo. / In this research, results from Reese; Schwalbe (1993) linear normalization methodology for deriving J-R curves are compared to those obtained from the traditional unloading elastic compliance technique. Both methodologies were applied to a nuclear grade steel A508-CL3A. Several miniaturized 0.394TC[S] specimens, were tested at typical NPV operating temperatures. Small scale testpieces were heat treated aiming to simulate the embritlemment exhibited by the structural steel when submitted to different levels of neutron exposure, whereas other specimens were tested in the as-received condition. All experimental and analytical procedures employed in this study have been fully computerized, including data acquisition, data refinement and J-R curve plotting, when the guidelines supplied by most recent version of ASTM standard for J-R curves, namely ASTM-E1820, were followed. The assessed variables affecting J-R curves behavior comprised crack propagation increment, number of load-Ioad line displacement data points, and it was also analyzed the agreement of the normalization method when compared to the compliance technique. Research results have shown that linear normalization is a trustworthy and very simple methodology to be applied in a vast range of mechanical behavior as sampled in this study, as long as computer programming is employed.