Dowel bars in jointed plain concrete pavement (JPCP) have the important function of transferring wheel loads from one slab to the other, hence ensuring that the deflections on each side of the joint are kept almost equal. As well, the dowels should not impede the concrete pavement movements due to environmental effects (temperature and moisture). Dowel bar misalignment, attributed to deficient construction practice, is a major cause of joint distress or faulting by inhibiting the free movement of the slab at the joint. To prevent these issues, tolerance guidelines on misalignment levels are implemented by transportation agencies. Review of previous studies indicate that many researchers analysed the effects of dowel bar misalignment on pavement behaviour using a pull-out test, that is a forcebased opening of the joint. These approaches neglect that joints movements in the field are strain-governed by non-linear temperature and shrinkage actions, leading to combined axial movements and curling of the slab. In this study, the fundamental dowel bar behaviour under shrinkage and thermal loading was determined through detailed 3D finite element modelling (3D-FEM). To that end, models of dowel jointed concrete slabs were developed and subjected to realistic non-linear profiles of shrinkage and thermal strains. Studies were carried out on a single-bar model, taking into account bar-concrete friction and plastic concrete behaviour. The parameters that were investigated included different configurations and levels of bar misalignment and different friction coefficients between the steel and the concrete, simulating the use of bond-breakers. To interpret the results from the numerical analysis, criteria for concrete damage were developed and used in parallel with measures of joint load transfer efficiency; these were obtained by examining the response of the slab under a Falling Weight Deflectometer (FWD) drop at the joint. The results were verified by comparing the outputs of a model consisting of one half of a slab to published data. The analysis of the models revealead that none of the models showed signs of significant damage after the application of shrinkage and two thermal cycles. Analyses with up to ten thermal cycles did not indicate progressive accumulation of damage, suggesting that for the chosen parameters there is no the concrete around the dowel bar will not fail. Models with bars placed higher in the slab and bars with angular misalignment exhibited more damage than the non-misaligned models without reaching the damage criteria used in this study. The models did not exhibit the amount of damage reported in the studies on dowel bar misalignment having used pull-out tests. It was found that no significant difference existed between uncoated and coated dowel bars models results with regards to concrete damage at the joint. However, a high coefficient of friction between the dowel and the concrete, simulating dowel bar corrosion, proved to be the most detrimental to joint integrity. All of the models performed very well with respect to joint load transfer efficiency, suggesting that the plastic strains in the concrete around the dowel did not have a significant impact on joint performance for the realistic range of parameters investigated.

Hedging a contingent claim with an asset which is not perfectly correlated with the underlying asset results in an imperfect hedge. The residual risk from hedging with a correlated asset is priced using an actuarial standard deviation principle in infinitesmal time, which gives rise to a nonlinear partial differential equation (PDE). A fully implicit, monotone discretization method is developed for solving the pricing PDE. This method is shown to converge to the viscosity solution. Certain grid conditions are required to guarantee monotonicity. An algorithm is derived which, given an initial grid, inserts a finite number of nodes in the grid to ensure that the monotonicity condition is satisfied. At each timestep, the nonlinear discretized algebraic equations are solved using an iterative algorithm, which is shown to be globally convergent. Monte Carlo hedging examples are given, which show the standard deviation of the profit and loss at the expiry of the option.

Dowel bars in jointed plain concrete pavement (JPCP) have the important function of transferring wheel loads from one slab to the other, hence ensuring that the deflections on each side of the joint are kept almost equal. As well, the dowels should not impede the concrete pavement movements due to environmental effects (temperature and moisture). Dowel bar misalignment, attributed to deficient construction practice, is a major cause of joint distress or faulting by inhibiting the free movement of the slab at the joint. To prevent these issues, tolerance guidelines on misalignment levels are implemented by transportation agencies. Review of previous studies indicate that many researchers analysed the effects of dowel bar misalignment on pavement behaviour using a pull-out test, that is a forcebased opening of the joint. These approaches neglect that joints movements in the field are strain-governed by non-linear temperature and shrinkage actions, leading to combined axial movements and curling of the slab. In this study, the fundamental dowel bar behaviour under shrinkage and thermal loading was determined through detailed 3D finite element modelling (3D-FEM). To that end, models of dowel jointed concrete slabs were developed and subjected to realistic non-linear profiles of shrinkage and thermal strains. Studies were carried out on a single-bar model, taking into account bar-concrete friction and plastic concrete behaviour. The parameters that were investigated included different configurations and levels of bar misalignment and different friction coefficients between the steel and the concrete, simulating the use of bond-breakers. To interpret the results from the numerical analysis, criteria for concrete damage were developed and used in parallel with measures of joint load transfer efficiency; these were obtained by examining the response of the slab under a Falling Weight Deflectometer (FWD) drop at the joint. The results were verified by comparing the outputs of a model consisting of one half of a slab to published data. The analysis of the models revealead that none of the models showed signs of significant damage after the application of shrinkage and two thermal cycles. Analyses with up to ten thermal cycles did not indicate progressive accumulation of damage, suggesting that for the chosen parameters there is no the concrete around the dowel bar will not fail. Models with bars placed higher in the slab and bars with angular misalignment exhibited more damage than the non-misaligned models without reaching the damage criteria used in this study. The models did not exhibit the amount of damage reported in the studies on dowel bar misalignment having used pull-out tests. It was found that no significant difference existed between uncoated and coated dowel bars models results with regards to concrete damage at the joint. However, a high coefficient of friction between the dowel and the concrete, simulating dowel bar corrosion, proved to be the most detrimental to joint integrity. All of the models performed very well with respect to joint load transfer efficiency, suggesting that the plastic strains in the concrete around the dowel did not have a significant impact on joint performance for the realistic range of parameters investigated.

Nanoindentation has been widely used for measuring mechanical behavior of nanocrystalline (nc) metals that cannot be measured by tensile and compressive test. The hardness and elastic modulus are usually obtained by Oliver and Pharr method. However, this may not be true for materials showing viscoelastic characteristics. This study aims at clarifying the effect of testing parameters, especially loading rate and holding time, on the hardness and elastic modulus of a nanocrystalline Fe-51Ni coating obtained in nanoindentation tests as the material exhibits anelastic and creep characteristics. An analytical method based on the correspondence principle for linear viscoelasticity was developed. The holding displacement-time data obtained in indentation creep tests at a high loading rate of 20 mN/s were analyzed and material parameters related to the elastic, anelastic and creep characteristic were derived using a model containing one Maxwell unit and two Kelvin units. The anelastic deformation thus contains at least two relaxation processes having relaxation times of 0.37 s and 6.8 s, respectively and the creep deformation is described by a viscosity value of 4.2x104 GPa.s for the alloy in an as-deposited state. Moreover, electrodeposited (ED) Ni was analyzed by electron backscatter diffraction. Results indicated that the ED Ni exhibits a bimodal distribution of grain size. The grains having sizes larger than 2 £gm shows a strong fiber texture of <100>//ND, whereas the small grains (<2 £gm) are mainly randomly oriented.

The aims of this thesis to investigate the two step loading of Ti/APC-2 hybrid nanocomposite laminates and their notched effect. Ti/APC-2 laminates were composed of three layers of titanium sheets and two layers of APC-2. Nanoparticles SiO2 were dispersed uniformly on the interfaces of APC-2 with the optimal amount of 1 wt %. Then, APC-2 was stacked according to cross-ply [0/90]s and quasi-isotropic [0/45/90/-45] sequences. The modified diaphragm curing process was adopted to fabricate the hybrid panels for minimal impact of production. The panels were cur into samples and drilled an diameter hole in the center with diameters of 4 or 6 mm. Both tension and fatigue tests were carried out with MTS 810 universal testing machine at room temperature. Also, two-step loading tests include high¡÷low and low¡÷high tests, were conducted. 0.9£mnom is denoted as high load and 0.7£mnom low load for two-step loading spectrum. In both high¡÷low and low¡÷high step loadings the first step is to do cyclic tests at a half life of the corresponding load, and then finish it due to last step load. From the received results, some conclusions were made. First, the ultimate load of notched cross-ply samples was reduced about 50% and the notched quasi-isotropic samples reduced about 30% compared to their unnotched counterparts. Second, the S-N curves are very close for both centrally notched samples of diameters 4 mm and 6 mm in cross-ply and quasi-isotropic samples. Third, quasi-isotropic samples had higher average values of cumulative damage than cross-ply samples. Because of notched effect centrally notched samples of diameters 4 mm had higher average values of cumulative damage than centrally notched samples of diameters 6 mm.

Dredge cutting forces produced by the movement of the cutterhead through the sediment have been measured with the laboratory dredge carriage located at the Haynes Coastal Engineering Laboratory. The sediment bed that was used for the dredging test was considered to be relatively smooth and the sediment used was sand with a d50=0.27 mm. Forces on the dredge carriage were measured using five 13.3 kN (3000 lb) one directional load cells placed on the dredge ladder in various places so the transmitted cutting forces could be obtained. The objectives for this study are to determine the vertical, horizontal, and axial forces that are produced by the cutterhead while testing. So, to find these cutter forces, a static analysis was performed on the carriage by applying static loads to the cutterhead in the vertical, horizontal, and axial directions, and for each load that was applied, readings were recorded for all five of the load cells. Then, static equilibrium equations were developed for the dredge carriage ladder to determine loads in the five load cells. Also, equilibrium equations can be applied to a dredging test to find the cutterhead forces by taking the measured data from the five load cells and applying the known forces to the equations, and the cutterhead forces can be determined. These static equilibrium equations have been confirmed by using a program called SolidWorks, which is modeling software that can be used to do static finite element analysis of structural systems to determine stresses, displacement, and pin and bolt forces. Data that were gathered from the experimental procedure and the theoretical calculations show that the force on the dredge cutterhead can be determined. However, the results from the static equilibrium calculations and the results from the SolidWorks program were compared to the experiment procedure results, and from the comparison the procedure results show irregularities when a force of approximately 0.889 kN (200 lb) or above is applied to the cutterhead in a north, south, west, or east orientation. The SolidWorks program was used to determine the results for displacements of the dredge carriage ladder system, which showed that large displacements were occurring at the location of the cutterhead, and when the cutterhead displaces it means that the carriage ladder is also moving, which causes false readings in the five load cells. From this analysis it was determined that a sixth force transducer was needed to produce more resistance on the ladder; and the cell #1 location needed to be redesigned to make the ladder system as rigid as possible and able to produce good testing results. The SolidWorks program was used to determine the best location where the sixth force transducer would give the best results, and this location was determined to be on the lower south-west corner oriented in the direction east to west. The static equilibrium equations were rewritten to include the new redesigned cell #1 location and the new location of the sixth load cell. From the new system of equations, forces on the cutterhead can be determined for future dredging studies conducted with the dredge carriage. Finally, the forces on the laboratory cuttersuction dredge model cutterhead were scaled up to the prototype 61 cm (24 in) cuttersuction dredge. These scaled up cutting forces on the dredge cutterhead can be utilized in the design of the swing winches, swing cable size, ladder supports, and ladder.

Mechanical loading is an integral component to maintaining bone mass during periods of disuse (i.e. bedrest or casting) or reduced weightbearing activity. Recent data has shown a direct relation between the sympathetic nervous system (SNS) and bone metabolism, however the underlying mechanisms responsible for this relationship are unknown. Furthermore, the role that beta adrenergic stimulation during disuse has on cancellous bone mass and microarchitecture have yet to be defined. The central hypothesis of this research is that resistance exercise and beta-1 adrenergic (Adrb1) receptor agonist administration attenuate disuse-associated reductions in metaphyseal bone during 28 days of rodent hindlimb unloading (HU). Study one determined whether an eccentric- (ECC) or combined isometric+eccentric- (ISO+ECC) based contraction paradigm, engaged during hindlimb unloading (HU), mitigates losses in musculoskeletal mass and strength. Both simulated resistance training (SRT) protocols inhibited reductions in disuse-sensitive cancellous bone mass and maintained plantarflexor muscle strength. Study two determined whether combining the anabolic effects of SRT with the anti-resorptive effects of alendronate (ALEN) during HU positively impacts cancellous bone in an additive or synergistic fashion. ALEN significantly inhibited the anabolic response of cancellous bone to SRT during HU. Study three determined whether an Adrb1 receptor agonist (dobutamine; DOB) mitigates disuse-associated losses in bone mass and formation rate (BFR) during HU. DOB administration significantly blunted reductions in bone mineral density (vBMD) by maintaining cancellous BFR. Study four determined if Adrb1 receptor agonist administration during HU results in an attenuation of osteocyte apoptosis within cancellous bone and whether this relates to a decrease in Bax/Bcl-2 mRNA content ratio (pro- and anti-apoptotic proteins). HU significantly increased cancellous bone osteocyte apoptosis and Bax/Bcl-2 mRNA content ratio, which was reduced by the administration of DOB. Collectively, these are the first studies to assess the role of beta-1 adrenergic signaling and resistance exercise in mitigating disuse-induced loss of cancellous bone mass in rodents. The long term goals of this research are to understand the exact molecular mechanisms by which both Adrb1 signaling and high intensity resistance exercise provide beneficial bone effects during prolonged periods of disuse and to apply these findings to current osteoporosis research.

名古屋大学博士学位論文 学位の種類 : 医学博士(論文) 学位授与年月日:平成4年7月20日 宮口和彦氏の博士論文として提出された

ABSTRACT In the present study, it is emphasized that mixed-type finite element formulation, which is different from the conventional displacement-type formulation, has both displacements and stresses as its primary variables. Therefore, stress, as well as displacement boundary conditions, can be imposed easily and exactly. Except around the outer edge where support is placed, stresses obtained by both displacement and mixed formulation are close to each other when the circular plate is subject to transverse uniform loading. However, large discrepancies exist around the locations of constraints, where the stresses are always significant and critical. Since mixed formulation of the present study can completely satisfy the stress and displacement boundary conditions, it can theoretically provide more accurate stress analysis and should be considered as a more appropriate analysis tool.

As we all know that Taiwan is an island surrounded by oceans. Around the island are many international commercial harbors, domestic fishery harbors and harbors for industrial purposes. However, these harbors are facing safety challenges from the strong wind induced waves during monsoon seasons and typhoon due to tropical depressions. The material degradation, fatigue induced from vibrations and the forced deformation of the whole structural system can not usually be observed until serious damages are realized. It is too late to do the fixing job or to replace the damaged components for the harbor while spending multi-million dollars on rebuilding the damaged facilities is the left choice. If we may find the gradual damages of the harbor in advance and establish a procedure to do the minor fixing or correcting works then during the hash environmental situations the serious damages may be prevented and lots of money can be saved also. There are many ways to do a routine inspection on the structures. However, for the structures in the harbor usually it is not quite easy to do this due to the fact that most structures are under the water. Therefore how to find the efficient and economic methods to investigate the harbor damages corresponding to various material constructions and based on the examination results to establish an alert system and to grade the damage-state will be important. The investigation methods may generally be divided into a general method and method of more detailed. The general methods usually need more experiences but less equipment. However, for the more detailed examination, more advanced equipment and scheme are required. After the inspection how to coordinate the raw data and find the relationship between the data and the damage-state of the structure will be one of the tasks. It is the purpose of this project to find efficient means for the inspection and set up a standard procedure to inspect the harbor structures routinely. In terms of the method, timing, schedule, frequency and appropriateness the evaluation standard for the structural damage is suggested and based on the evaluated results the damage grade is defined quantitatively for the harbor structures. Thus the harbor bureau may effectively manage the harbor structure and maintain the operational safety for the harbor.