Back pain is the second most common neurological ailment in the United States and the leading cause of pain and disability. More than 80% of the total US population experiences back-pain during their life time and the annual back pain related healthcare costs exceed 100 billion dollars. While the exact cause of low back pain (LBP) is still unknown, degeneration of the intervertebral disc (IVD) has been suggested as a primary contributor. IVD is the largest avascular tissue in the human body and it is composed of three integrated tissues (annulus fibrosus - AF, nucleus pulposus - NP and cartilaginous end plate - CEP). IVD functions as a shock-absorber during motion and provides flexibility to motion of the spine. Maintaining IVD tissue integrity is an energy demanding process. Studies have shown that mechanical loading affects cellular biosynthesis of IVD tissue and may also promote IVD degeneration. However the path to this effect is still unknown. We propose a link between mechanical loading and cell energy production which contributes to altered cellular biosynthesis. Thus, we investigated the effects of mechanical loading on IVD cell energy metabolism under various mechanical loading regimes. Porcine AF and NP cells were isolated and seeded in 2% agarose at a 5,000,000 cells/mL cell density. A custom made bioreactor was used to conduct compression experiments. The experiment groups were: 15% static compression; 30% static compression; 0.1, 1 and 2 Hz dynamic compression at 15% strain magnitude. Experiment duration was 4 hr. ATP concentration in cell-agarose construct and culture media were measured using Luciferin-luciferase method to evaluate ATP production and ATP release from cells respectively. Lactate concentration in media was measured using lactate dehydrogenase enzymatic assay. Nitrite (stable metabolite of nitric oxide - NO) concentration in media was measured by Greiss Assay. DNA content per sample was measured using fluorometric assay. DNA content per sample was used as an internal control; all compressed samples were then normalized to unstrained control group. ATP production of AF cells was up regulated by static and dynamic mechanical loading. Data suggests that AF cell response to mechanical loading is primarily loading amplitude dependent. NP cells exhibited an increased ATP production at 1 Hz dynamic loading but remained comparable to control samples at other tested conditions. AF cells produced an increase in NO production at 1-, 2 Hz dynamic loading. NO production of NP cells was up regulated by mechanical loading at all tested conditions. ATP release was up regulated at higher frequencies in AF cells. In addition to higher frequencies (1 Hz and 2 Hz) NP cell ATP release was also up regulated by 30% static compression. Thus, this study clearly illustrates that mechanical loading affects IVD cell energy production.

The loading problem in a Flexible Manufacturing System (FMS) lies in the allocation of operations and associated cutting tools to machines for a given set of parts subject to capacity constraints. This dissertation proposes a hierarchical approach to the machine loading problem when the workload and tool magazine capacity of each machine are restrained. This hierarchical approach reduces the maximum workload of the machines by partially grouping them. This research deals with situations where different groups of machines performing the same operation require different processing times and this problem is formulated as an integer linear problem. This work proposes a solution that is comprised of two phases. In the first phase (Phase I), demand is divided into batches and then operations are allocated to groups of machines by using a heuristic constrained by the workload and tool magazine capacity of each group. The processing time of the operation is different for each machine group, which is composed of the same identical machines; however, these machines can perform different sets of operations if tooled differently. Each machine and each group of machines has a limited time for completing an operation. Operations are allocated to groups based on their respective workload limits. In the second phase (Phase II), demand is divided into batches again and operations are assigned to machines based on their workload and tool magazine capacity defined by Longest Processing Time (LPT) and Multifit algorithms. In Phase II, like Phase I, partial grouping is more effective in balancing the workload than total grouping. In partial grouping, each machine is tooled differently, but they can assist one another in processing each individual operation. Phase I demonstrates the efficiency of allocating operations to each group. Phase II demonstrates the efficiency of allocating operations to each machine within each group. This two-phase solution enhances routing flexibility with the same or a smaller number of machines through partial grouping rather than through total grouping. This partial grouping provides a balanced solution for problems involving a large number of machines. Performance of the suggested loading heuristics is tested by means of randomly generated tests.

This study presents a method for predicting the undrained behavior of plate anchors, including out-of-plane loading of simple plates and performance of suction embedded plate anchors (SEPLA). Three dimensional finite element models are used to investigate the behavior of square and rectangular plate anchors under normal loading with eccentricity in any direction. Upper bound analyses are performed for parallel loading and torsion loading. A simple model is then fit to the FE and upper bound solutions to determine required fitting parameters for both square and rectangular plates. The simple models can, in turn, be used both to predict anchor capacity and as yield surfaces for conducting plastic limit analyses, a method capable of predicting post yield anchor trajectory. The model predictions are shown in reasonable good agreement with the experimental results. For SEPLA, a theoretical model of plastic limit analysis is developed to predict the trajectory during the “keying” process and the ultimate capacity after the “keying” is complete. The predicted results are consistent with relevant known solutions.

Most studies that have examined chloride-induced corrosion of steel in concrete have focused on sound concrete. However, reinforced concrete is seldom uncracked and very few studies have investigated the influence of cracked concrete on rebar corrosion. Furthermore, the studies that have examined the relationship between cracks and corrosion have focused on unloaded or statically loaded cracks. However, in practice, reinforced concrete structures (e.g. bridges) are often dynamically loaded. Hence, the cracks in such structures open and close which could influence the corrosion of the reinforcing steel. Consequently, the objectives of this project were (i) to examine the effect of different types of loading on the corrosion of reinforcing steel, (ii) the influence of concrete mixture design on the corrosion behaviour and (iii) to provide data that can be used in service-life modelling of cracked reinforced concretes. In this project, cracked reinforced concrete beams made with ordinary Portland cement concrete (OPCC) and high performance concrete (HPC) were subjected to no load, static loading and dynamic loading. They were immersed in salt solution to just above the crack level at their mid-point for two weeks out of every four (wet cycle) and, for the remaining two weeks, were left in ambient laboratory conditions to dry (dry cycle). The wet cycle led to three conditions of exposure for each beam: (i) the non-submerged region, (ii) the sound, submerged region and (ii) the cracked mid-section, which was also immersed in the solution. Linear polarization resistance and galvanostatic pulse techniques were used to monitor the corrosion in the three regions. Potentiodynamic polarization, electrochemical current noise and concrete electrical resistance measurements were also performed. These measurements illustrated that (i) rebar corroded faster at cracks than in sound concrete, (ii) HPC was more protective towards the rebar than OPCC even at cracks and (iii) there was a minor effect of the type of loading on rebar corrosion within the period of the project. These measurements also highlighted the problems associated with corrosion measurements, for example, identifying the actual corroding area and the influence of the length of rebar. The numbers of cracks and crack-widths in each beam were measured after the beam’s initial exposure to salt solution and, again, after the final corrosion measurements. HPC beams had more cracks than the OPCC. Also, final measurements illustrated increased crack-widths in dynamically loaded beams, regardless of the concrete type. The cracks in both statically and dynamically loaded OPCC and HPC beams bifurcated at the rebar level and propagated parallel to the rebar. This project also examined the extent of corrosion on the rebars and the distribution of corrosion products in the concrete and on the concrete walls of the cracks. Corrosion occurred only at cracks in the concrete and was spread over a larger area on the rebars in HPC than those in OPCC. The damage due to corrosion was superficial in HPC and crater-like in OPCC. Regardless of the concrete type, there was a larger distribution of corrosion products on the crack walls of the dynamically loaded beams. Corrosion products diffused into the cement paste and the paste-aggregate interface in OPCC but remained in the crack in HPC. The most voluminous corrosion product identified was ferric hydroxide. Elemental analysis of mill-scale on rebar which was not embedded in concrete or exposed to chlorides was compared to that of the bars that had been embedded in uncontaminated concrete and in cracked concrete exposed to chlorides. In uncontaminated concrete, mill-scale absorbed calcium and silicon. At a crack, a layer, composed of a mixture of cement paste and corrosion products, developed between the mill-scale and the substrate steel. Based on the results, it was concluded that (i) corrosion occurred on the rebar only at cracks in the concrete, (ii) corrosion was initiated at the cracks immediately upon exposure to salt solution, (ii) the type of loading had a minor influence on the corrosion rates of reinforcing steel and (iv) the use of polarized area led to a significant underestimation of the current density at the crack. It is recommended that the effect of cover-depth on (i) the time to initiation of corrosion and (ii) the corrosion current density in cracked concrete be investigated.

In order to increase the independence in everyday life of the elderly population, we have developed a lifting aid for loading in the private car trunk. Independence from outside assistance affects self-esteem in a positive direction and can help increase the quality of life for a large group of individuals. As people age and experience changes in performance, it is important that aids and support is available, particularly to reduce the experience of aging and it’s increasing physical limitations. The aim was to develop a function prototype characterized by simplicity, which facilitates loading of the private car trunk. The project was conducted at the request of Autoadapt AB, which is one of the leading actors in car adaptations for individuals with disablilities. A function prototype of the product Easy Load has been produced through dynamic product development and its various tools. In an attempt to meet the requirements of simplicity and ease of use, concepts such as universal design and usability affected the project. In order to find a user need that could form the basis of the project, proceedings began with a pre-study that included observations and group interviews of members in a pensioner club in Halmstad. The Product development work continued with several brainstorming sessions with participants from a number of the university's engineering programs. Ideas from the sessions, together with the results from the benchmarking, formed the basis for final product design and function. A key requirement was that the product could be fitted in sedan car models with easy grips and without any permanent fixings. Construction of the prototype was made mostly in the University’s mechanical workshop, using both self-constructed and sourced components. Stress and installation testing and risk analysis pursuant to FMEA highlighted deficiencies that the project group sought to adjust. In cases where this did not happen, the project group made concrete improvement proposals to simplify further development. This project shows that lifting aids products without permanent fixings are possible to develop for use in sedan car models. Specific product criteria have been met through a designed function prototype for loading in the private car trunk.

Most studies that have examined chloride-induced corrosion of steel in concrete have focused on sound concrete. However, reinforced concrete is seldom uncracked and very few studies have investigated the influence of cracked concrete on rebar corrosion. Furthermore, the studies that have examined the relationship between cracks and corrosion have focused on unloaded or statically loaded cracks. However, in practice, reinforced concrete structures (e.g. bridges) are often dynamically loaded. Hence, the cracks in such structures open and close which could influence the corrosion of the reinforcing steel. Consequently, the objectives of this project were (i) to examine the effect of different types of loading on the corrosion of reinforcing steel, (ii) the influence of concrete mixture design on the corrosion behaviour and (iii) to provide data that can be used in service-life modelling of cracked reinforced concretes. In this project, cracked reinforced concrete beams made with ordinary Portland cement concrete (OPCC) and high performance concrete (HPC) were subjected to no load, static loading and dynamic loading. They were immersed in salt solution to just above the crack level at their mid-point for two weeks out of every four (wet cycle) and, for the remaining two weeks, were left in ambient laboratory conditions to dry (dry cycle). The wet cycle led to three conditions of exposure for each beam: (i) the non-submerged region, (ii) the sound, submerged region and (ii) the cracked mid-section, which was also immersed in the solution. Linear polarization resistance and galvanostatic pulse techniques were used to monitor the corrosion in the three regions. Potentiodynamic polarization, electrochemical current noise and concrete electrical resistance measurements were also performed. These measurements illustrated that (i) rebar corroded faster at cracks than in sound concrete, (ii) HPC was more protective towards the rebar than OPCC even at cracks and (iii) there was a minor effect of the type of loading on rebar corrosion within the period of the project. These measurements also highlighted the problems associated with corrosion measurements, for example, identifying the actual corroding area and the influence of the length of rebar. The numbers of cracks and crack-widths in each beam were measured after the beam’s initial exposure to salt solution and, again, after the final corrosion measurements. HPC beams had more cracks than the OPCC. Also, final measurements illustrated increased crack-widths in dynamically loaded beams, regardless of the concrete type. The cracks in both statically and dynamically loaded OPCC and HPC beams bifurcated at the rebar level and propagated parallel to the rebar. This project also examined the extent of corrosion on the rebars and the distribution of corrosion products in the concrete and on the concrete walls of the cracks. Corrosion occurred only at cracks in the concrete and was spread over a larger area on the rebars in HPC than those in OPCC. The damage due to corrosion was superficial in HPC and crater-like in OPCC. Regardless of the concrete type, there was a larger distribution of corrosion products on the crack walls of the dynamically loaded beams. Corrosion products diffused into the cement paste and the paste-aggregate interface in OPCC but remained in the crack in HPC. The most voluminous corrosion product identified was ferric hydroxide. Elemental analysis of mill-scale on rebar which was not embedded in concrete or exposed to chlorides was compared to that of the bars that had been embedded in uncontaminated concrete and in cracked concrete exposed to chlorides. In uncontaminated concrete, mill-scale absorbed calcium and silicon. At a crack, a layer, composed of a mixture of cement paste and corrosion products, developed between the mill-scale and the substrate steel. Based on the results, it was concluded that (i) corrosion occurred on the rebar only at cracks in the concrete, (ii) corrosion was initiated at the cracks immediately upon exposure to salt solution, (ii) the type of loading had a minor influence on the corrosion rates of reinforcing steel and (iv) the use of polarized area led to a significant underestimation of the current density at the crack. It is recommended that the effect of cover-depth on (i) the time to initiation of corrosion and (ii) the corrosion current density in cracked concrete be investigated.

Dynamic properties of soils (shear stiffness and damping ratio) are critical for the design of structures subjected to vibrations. The dynamic properties of a benchmark standardized laboratory sand (Ottawa silica sand) were evaluated with two different resonant column devices, utilising software with different analytical approaches for the evaluation of soil properties. The dynamic properties (shear modulus and damping ratio) are evaluated as a function of the shear strain level. The results are compared to evaluate the effect of the type of equipment and the form of the data analysis on the measured dynamic properties of the samples. The results are discussed in light of the applicability of the procedures in practice, the ease of the testing methods, and the errors they introduced into analysis and design. In general, the shear wave velocities obtained from the two different devices are in good agreement. However, the damping ratios they give show considerable differences as strains increase. Dynamic properties are typically measured by curve fitting of the transfer function between the excitation and the response using the resonant column device. However, the force function generated by sinusoidal sweep or random noise excitations induce different shear strain levels at different frequencies. Consequently, the shape of the measured transfer function is distorted and differs from the theoretical transfer function for an equivalent single-degree-of-freedom system. The difference between the measured and theoretical transfer functions as well as the bias in the computed dynamic properties becomes more pronounced with the increase in shear strain. This study presents a new methodology for the evaluation of dynamic properties from an equivalent constant-strain transfer function. The soil specimen is excited simultaneously using a sinusoidal excitation (carrier signal) at the required strain level and a small amplitude, narrow band random noise. The strain level induced by the fixed sine is shown to control the resonant frequency of the specimen; whereas the random noise introduces the required frequency bandwidth to determine the transfer function and hence the dynamic properties at a constant strain level. The new methodology also shows a good potential for the evaluation of frequency effects on the dynamic properties of soils in resonant column testing.

The objective of this study is design and manufacture a tube hydroforming machine with counter feeding and axial feeding, which includes a forming apparatus, hydraulic system and control system. Using computer program to execute the loading path and correct by sensors. To test the function of the machine, carry out the experiments of T,Y-shape hydraulic bulging with annealed AA6063-T5 and 6011A aluminum, which by different working path, and using the experiments to analyze the influences of these parameters on the formability of the tubes.

The experimental tests and analysis of a fuel cell unit and a 150 W fuel cell stack are performance in this research. The experimental items in this study are various the types of flow channels, fasten torque, inlet gas pressure, Pt loading density, oxidizers, electron collector type etc. Through above a series of the tests, we can understand the key factors which influence the performance of the PEMFC. The experimental results can also provide us references when one assemble a fuel cell stack in future. PEMFC can start quickly at low temperature and achieves stable output voltage. When the 8 N-M torque is applied to fasten the reaction chamber, the contact resistance between electrode and electron collector reaches a minimum value. By designing the flow channel properly, the membrane hydration can remain a good state so that the conductivity of the proton exchange membrane can not be hinder. We found that the optimum channel among three types of the test channels is the conventional channel with the rib width 2 mm. When the output power is largest. Our experiments display that the increase of Pt loading in cathode can improve PEMFC performance. At certain voltage, there is a critical value in Pt loading. PEMFC performance can not be improved when Pt loading increases over this value. When the inlet pressure in cathode side increase to 10~20 psi higher than the pressure in anode side, the output power can improve apparently. Keyword: Proton exchange membrane, Pt loading, electron collector.

Abstract The study on SOC of article is one of package way for CSP. The SOC transmits messages by Solder Ball joining the board. It can make the volume of product decrease, but the reliability reduces on using. So the reliability of Solder Ball is a very important topic for study. The article for Solder Ball uses the Mixed-Viscoplastic way to simulate the warpage state of SOC when the temperature of Solder Ball rises by ANSYS. Then using the Viscoplastic material parameter simulates the acts by TCT experiment and checks the suitable Fatigue Model to get the analysis results turn into the reliability data. The reliability data puts to the proof with the experimental reliability data and compares differences to other documents.