A methodology for making a spring back behaviour of hole expansion in gas tank. Work is initiated for SAAb automobile and the geometry of model is created by using the software’s called Unigraphics and hyper mesh and secondly the simulation of the model is done in Ls-dyna to know the spring back behaviour of hole with various depth and positions of the punch. The yield strength of the element and stress, strain distribution and different radius of the blank are used to reduce the cracks at the lower edge of the blank. Steel material is used and the thickness of the material (0.229mm). The simulation of the work includes loading of punch and its displacement. This study demonstrates the efficiency of the model to simulate the hole expansion and better understanding of the expansion of radius and spring back angle. / Measurement of spring back behaviour

A two dimensional continuous numerical model based on Discrete Element Method is used to investigate the behaviour of accretionary wedges with different basal frictions. The models are based on elastic-plastic, brittle material and computational granular dynamics, and several characteristics of the influence of the basal friction are analysed. The model results illustrate that the wedge’s deformation and geometry, for example, fracture geometry, the compression force, area loss, displacement, height and length of the accretionary wedge etc., are strongly influenced by the basal friction. In general, the resulting wedge grows steeper, shorter  and higher, and the compression force is larger when shortened  above a larger friction basement.  Especially, when there is no basal friction, several symmetrical wedges will distribute symmetrically in the domain. The distribution of the internal stress when a new accretionary prime is forming is also studied. The results illustrate that when the stress in a certain zone is larger than a critical number, a new thrust will form there.

In this bachelor thesis an attempt is made to recreate the shoreline of Gotland during the Bronze Age. This has been done with the help of GIS to analyze remains dated to different periods of the Bronze Age that have been situated close to the coast. Case studies of three areas of the island have been made where dated remains together with typical Bronze Age remains like cairns and ship settings are analyzed with variables such as height over sea level and geological and topographical information. Contemporary datings from each case study have been compared to find a possible shoreline for both early and late Bronze Age. Two shorelines, one for the early Bronze Age and one for the late Bronze Age, have been created and tested on the three areas to see the placement of the remains in relation to these coastlines.

Syfte Syftet med denna studie var att undersöka sensitiviteten och specificiteten hos BMI vid klassificering av övervikt, samt att jämföra gränsvärdena för övervikt mätt med BMI med gränsvärdena för övervikt mätt i fettprocent med BodPod. Metod Urvalet i studien bestod av 359 deltagare mellan 30-50 år (medelvärde – 39,7 år). Av dessa 359 var 192 kvinnor och 167 män. Deltagarna var indelade i fyra aktivitetsnivåer – stillasittande, lågaktiva, aktiva och mycket aktiva. Dessa delades in i två grupper där stillasittande och lågaktiva slogs ihop och aktiva och mycket aktiva slogs ihop. Därefter har gränsvärden för övervikt jämförts, mätt med två olika mätinstrument – BMI (body mass index) och ADP (air displacement plethysmography) samt givit nya förslag på gräns för övervikt med BMI som mätinstrument. Sensitiviteten och specificiteten för BMI för män och kvinnor och olika aktivitetsnivåer har uppmäts. Resultat Resultatet visade att gränsvärdena för övervikt hos kvinnor bör fortfarande ligga runt 25, oavsett aktivitetsnivå, men för män bör gränsvärdena ligga mellan 26-27, beroende på aktivitetsgrad. Sensitiviteten för kvinnor ligger mellan 69-76% beroende på aktivitetsgrad och specificiteten är 83-91%. För män ligger sensitiviteten mellan 76-88% beroende på aktivitetsgrad och specificiteten är 56-68%. Med föreslagna nya BMI-gränser minskar sensitiviteten för män, men specificiteten ökar. Ingen större förändring hos kvinnor. Slutsats Då sensitiviteten och specificiteten är relativt låg för BMI kan det vara bra för en lärare i idrott och hälsa att känna till BMI:s begränsningar. Idrottslärare ska utveckla elevens färdigheter och kunskap inom hälsa och bör lyfta BMI:s styrkor och svagheter i undervisningen eftersom det är ett mått de flesta känner till. BMI är inte ett perfekt mått utan bör kompletteras med andra enkla mätmetoder. Om olika BMI gränsvärden för olika aktivitetsnivåer ska användas bör denna mätning vara mer ingående och inkludera träning på fritiden, vilket inte gjorts i denna studie. / Aim The aim of this study was to examine the sensitivity and specificity of BMI for classification of overweight, as well compared the cutoffs for overweight measured with BMI with the cutoffs for overweight measured in %FM with BodPod. Method The selection of the study consisted of 359 participants between 30-50 years of age (mean age – 39,7 years). Of these 359, 192 were women and 167 were men. The participants were divided into four activity levels – sedentary, low active, active, very active. These were divided into two groups – sedentary and low active into one group and active and very active into another. Then cutoffs for overweight were measured, with two different methods – BMI (body mass index) and ADP (air displacement plethysmography), as well given new suggestions for cutoff levels for overweight measured with BMI. The sensitivity and specificity, for BMI, for men and women and different levels of activity were calculated. Result The result showed that the cutoffs for overweight in women still should be around 25, no matter the level of activity, but for men cutoffs should be between 26-27, considering level of activity. Sensitivity for women is between 69-76% depending on level of activity and specificity 83-91%. For men the sensitivity is between 76-88% depending on level of activity and the specificity 56-68%. With suggested new BMI cutoffs the sensitivity for men decreases, but the specificity increases. No larger change for women. Conclusion As the sensitivity and specificity is relatively low for BMI it could be good for teachers in physical education to know of BMI limitations. PE teachers are supposed to develop the pupils’ skills and knowledge in health and should inform about BMI strengths and weaknesses in education since it is a measure known by most. BMI is not a perfect measurement but should be accompanied by other simple measurements. If BMI cutoffs should take activity into account, this measurement should be more detailed and include physical activity in their leisure time, which was not done in this study.

Improved efficiency, better controllability and low noise are the most demanding features form a displacement machine now-a-days. Most of the conventional displacement machines are basically a reciprocating pumping element controlled by valve plates or with the help of check valve [1]. This kind of hydraulic machines loose efficiency dramatically at partial displacement because all of the pistons remain at high pressure at the cycle time and due to pressure inside the piston leakage and shear losses increases. One approach to improve the efficiency of the displacement machine can be controlling each hydraulic piston by using programmable faster valves called digital valve. As the total displacement will be controlled digitally, the total system is called Digital Displacement Technology. In digital displacement machine it is possible to disconnect some of the pistons from the load and the piston will connect only with the low pressure side, minimizing losses due to leakage and shear. As the valve will control directly with digital controller it will eliminate the necessity of servo-hydraulic control required by conventional systems. Digital valves can open fully and close again with the input signal within one revaluation of the shaft, so it gives better control to the pumping element results reduction in hysteresis and increase the linearity of the pumping element. In Digital Displacement machines by controlling the valves pistons are connected with the machine when pressure is equal, but in the traditional machines piston connection was pre-determined with the shaft angle. By doing the piston control efficiency of the machine will improve and the sound generates for the decompression flow will be reduced [17]. Also energy storage and recovery can be possible by using accumulator.

The Variable Displacement Engine (VDE) is a new generation of engines that are designed to decrease the fuel consumption at the cruise speed of a vehicle. The isolation of the VDE's new vibration pattern is beyond the capabilities of conventional mounts and bushings. Consequently, in this thesis, novel active and semi-active solutions are proposed to develop various semi-active and active hydraulic bushing proof-of-concept systems that may solve the isolation problem in a VDE system. <br /><br /> The dynamic stiffness response, which is the transfer function that relates the engine displacement to the transmitted force, is normally used as the key design criterion for engine mounts and bushings. In this thesis, a linear mathematical model of a conventional hydraulic bushing is purposed. The validity of the mathematical model is confirmed by an experimental analysis, and the various parameters in the dynamic stiffness equation are evaluated. The experimental results indicate that the dynamic stiffness frequency response of the conventional hydraulic bushing has both soft and stiff regions. The soft region is limited to low frequencies. For the VDE isolation, the goal is to provide a soft bushing for a wider range of frequencies than a conventional bushing can accommodate. Addition of a short inertia track, similar to a decoupler used in conventional hydraulic engine mounts, may be used to extend the soft region of a conventional hydraulic bushing, and the experimental results validate it. <br /><br /> Since the short inertia track provides no additional damping, a supplementary Magnetorheological (MR) valve is also devised. The MR valve has the advantage to minimize the amount of MR fluid used, which significantly reduces the cost of the overall system. The novel valve allows the damping coefficient of the bushing assembly to be controlled by varying the electrical current input to a solenoid coil. A mathematical model is derived for the MR bushing, and is validated experimentally. <br /><br /> In addition, an active bushing to solve the VDE isolation problem is purposed in this thesis. In this bushing, a magnetic actuator, composed of a permanent magnet and a solenoid coil, is included in the active bushing. This active chamber affects the dynamic stiffness response of the bushing by altering the bushing's internal pressure. The nonlinear equation of motion of the permanent magnet is linearized and is incorporated into the new mathematical model of the system. The new purposed model for the active bushing is in good agreement with the experimental results. This active chamber is also proved capable of producing complex dynamic stiffness frequency response. <br /><br /> The conclusion is that the proposals in this thesis can contribute to the isolation of the vibration pattern, imposed by the application of a VDE system.

<p>This dissertation aims to demonstrate the feasibility of direct infarct visualization using 3D medical ultrasound. The dissertation proceeds by providing the first ever demonstration of fully-sampled 3D ultrasonic speckle tracking using raw B-Mode data of the heart. The initial demonstration uses a Cramer-Rao lower bound limited displacement estimator. The dissertation then proceeds to develop an implementable method for biased time-delay estimation. Biased time-delay estimation is shown to surpass the traditional limits described by the Cramer-Rao lower bound in a mean square error sense. Additional characterization of this new class of estimator is performed to demonstrate that with easily obtainable levels of prior information it is possible to estimate displacements that do surpass the Cramer-Rao lower bound. Finally, using 2D and 3D realizations of biased displacement estimation (Bayesian speckle tracking) the passive strain induced in the ventricle walls during atrial systole is shown to be sufficient to distinguish healthy and chronically infarcted myocardium.</p> / Dissertation

Many bridges are damaged by collisions from over-height vehicles resulting in significant impact to the transportation network. To reduce the likelihood of impact from over-height vehicles, steel pedestals have been used as a cost-effective, efficient means to increase bridge clearance heights. However, these steel pedestals installed on more than 50 bridges in Georgia have been designed with no consideration of seismic loads and may behave in a similar fashion to high-type steel bearings. Past earthquakes have revealed the susceptibility of high-type bearings to damage, resulting in the collapse of several bridges. Although Georgia is located in a low-to-moderate region of seismicity, earthquake design loads for steel pedestals should not be ignored. In this study, the potential vulnerabilities of steel pedestals having limited strength and deformation capacity and lack of adequate connection details for anchor bolts is assessed experimentally and analytically. Full-scale reversed cyclic quasi-static experimental tests are conducted on a 40' bridge specimen rehabilitated with 19" and 33" steel pedestals to determine the modes of deformation and mechanisms that can lead to modes of failure. The inelastic force-deformation hysteretic behavior of the steel pedestals obtained from experimental test results is used to calibrate an analytical bridge model developed in OpenSees. The analytical bridge model is idealized based on a multi-span continuous bridge in Georgia that has been rehabilitated with steel pedestals. The analytical bridge model is subjected to a suite of ground motions to evaluate the performance of the steel pedestals and the overall bridge system. Recommendations are made to the Georgia Department of Transportation (GDOT) for the design and construction of steel pedestals. The results of this research are useful for Georgia and other states in low-to-moderate seismic zones considering the use of steel pedestals to elevate bridges and therefore reduce the likelihood of over-height vehicle collisions.

The effects of coupling parameters of active-passive and passive-passive coupling components on the coupling efficiency and signal mixed proportion for polymer optical fiber (POF) communication are investigated. A high sensitivity and easy fabricated POF displacement sensor is proposed by using cycling bending POF. Also, light sources for both Laser diode (LD) and light emitting diode (LED) are employed in this study. Experimental approaches and numerical analysis of rays tracing method and finite element method are performed to investigate the effects of coupling scheme and bent deformation on the optical power attenuation. Experimental results also illustrate the feasibility of using numerical analysis in coupling components and POF displacement sensor design. The effect of V-grooved array¡¦s POF on the coupling efficiency and signal mixed proportion are presented in active-passive components. The results indicate that the effect of the V-groove¡¦s shape and size on the coupling efficiency is very significant for all designed parameters of V-grooved array¡¦s POF. Compared with the parallel V-grooved array, the skew V-grooved array reduces the length of the coupling component and increases the output power between light source and POF. In the Y-branch POF coupler for passive-passive components, both the excess loss and the output power ratio of the Y-branch couplers are very sensitive to the couple angle, the coupling distance and the refractive index of the filling medium between the emitting-end and receiving-end of fibers. The results also show that the proposed model can be used to analyze the coupling efficiencies in the asymmetrical Y-branch or axial symmetrical couplers with acceptable accuracy. In the POF displacement sensor using by cycling bending loss, the results show that the effect of roller¡¦s number, interval and wavelength on light power attenuation is very significant. Based on the experimental data, a linear equation is derived to estimate the relationship between the power loss and the relative displacement. The difference between the estimated results and the experimental results is less than 8%.

In today&#039 / s technology severe working conditions increase demands on structural materials. A class of materials which are developed to meet these increased demands is Functionally Graded Materials (FGMs). These are inhomogeneous structural materials which are able to withstand large temperature gradients and corrosive environment. Application areas of FGMs are in aerospace industry, nuclear reactors, chemical plants and turbine systems. FGMs have gradual compositional variation from metal to ceramic which give them mechanical strength, toughness and heat resistance. However under high temperature gradients, cracking problems may arise due to thermal stresses. In layered structures the final stage of failure may be delamination due to crack extension. The objective of this study is to model a particular type of crack problem in a layered structure consisting of a substrate, a bond coat and an orthotropic FGM coating. There is an internal crack in the orthotropic layer and it is perpendicular to material gradation of coating. The position of the crack inside the coating is kept as a variable. The steady-state temperature distribution between the substrate and the coating causes a buckled shape along crack face. The critical temperature change, temperature distribution, mixed mode stress intensity values and energy release rates are calculated by using Displacement Correlation Technique. Results of this study present the effects of geometric parameters such as crack length, crack position, etc as well as the effects of the type of gradation on buckling behavior and mixed mode stress intensity factors.