This research study focuses on evaluating the design of HSC prestressed bridge girders. Specifically there were three major objectives. First, to determine the current state of practice for the design of HSC prestressed bridge girders. Second, to evaluate the controlling limit states for the design of HSC prestressed bridge girders and identify areas where some economy in design may be gained. Third, to conduct a preliminary assessment of the impact of raising critical design criteria with an objective of increasing the economy and potential span length of HSC prestressed girders. The first objective was accomplished through a literature search and survey. The literature search included review of design criteria for both the AASHTO Standard and LRFD Specifications. Review of relevant case studies of the performance of HSC prestressed bridge girders, as well all as of important design parameters for HSC were carried out. In addition, a survey was conducted to gather information and document critical aspect of current design practices for HSC prestressed bridges The second objective was accomplished by conducting a parametric study for single span HSC prestressed bridge girders to mainly investigate the controlling limit states for both the AASHTO Standard (2002) and LRFD (2002) Specifications. AASHTO Type IV and Texas U54 girder sections were considered. The effects of changes in concrete strength, strand diameter, girder spacing and span length were evaluated. Based on the results from the parametric study, the limiting design criteria for HSC prestressed U54 and Type IV girders using both the AASHTO Standard and LRFD Specifications for Highway Bridges were evaluated. Critical areas where some economy in design may be gained were identified. The third research objective was accomplished by evaluating the impact of raising the allowable tensile stress for service conditions. This stress limit was selected for further study based on the current limit for uncracked sections provided by the ACI 318 code (2002) and the limit used for a specific case study bridge (Ralls 1995). Recommendations for improving some critical areas of current bridge designs, as well as for increasing bridge span lengths, are given.

No description available.

Osteoarthritis (OA) is a degenerative joint disorder and one of the leading causes of disability in elderly. Tai Chi is seen to be effective in relieving symptoms of OA knee joint. The main aim of this study is to design a Tai Chi program and a strength training program for the elderly with knee OA and to compare the effects of these programs on the range of motion, gait, pain and balance. 20 participants age 55 and over were divided into two groups (Tai Chi and Strength training) based on predetermined criteria. Both the groups showed improvement in WOMAC scores, balance and strength following Tai Chi and strength training intervention for 2 months.

The primary purpose of this thesis was to understand the relationship between the variation in athlete segment lengths (trunk, thigh, shank) and front squat depth as represented by maximum thigh segment rotation angle within the recommended guidelines. A validated segmental anthropometric model was used to simulate the effects of progressively altering thigh and trunk lengths on front squat depth. Both the thigh and trunk lengths were independently progressed through +/- 3 standard deviations, using the anthropometry collected from 41 athletes. This was done for simulated subjects of short (1.65 m for male and 1.55 m for females), average (1.82 m for male and 1.70 m for female), and tall (2.01 m for male and 1.87 m for females) statures. As thigh length increased, the ability to perform a full front squat (to a thigh depth of 180 degrees relative to the right horizontal) decreased. Conversely, as trunk length decreased, the ability to perform a full front squat decreased. The model was modified to progressively alter the thigh-to-trunk ratio from 0.8 to 1.2 for individuals of short, average and tall statures. Effects were similar for all heights for both males and females. Individuals with a thigh-to-trunk ratio above 1 were simulated to not be able to achieve a full front squat. This effect was greater in tall individuals, followed by average and then short. The ankle flexibility measured from the 41 athletes was run in simulations to determine its effects on front squat depth. For 25 of the athletes, the ankle flexibility did not allow their knees to pass the vertical plane of the toes. Flexibility constraints were removed from the model and the knees were moved to the vertical plane of the toes, 5 cm past, and 10 cm past. When the knees were allowed to move to the vertical projection of the toes, 8 athletes could not achieve a full front squat. When the knees were allowed to move 5 cm past the vertical projection of the toes, all athletes were predicted to be able to achieve a full front squat. When ankle flexibility was factored into the model, the results predicted that 16 athletes could not achieve a full front squat. The effects of ankle flexibility on front squat depth appeared to be influenced by the thigh-to-trunk ratio. Of the eight participants predicted not to be able to achieve a full front squat when the knees were allowed to reach the vertical projection of the toes, five had the largest thigh-to-trunk ratios. Athletes with a thigh-to-trunk ratio of 1 or greater may physically not be able to complete a full front squat according to the NSCA guidelines. It is however, more likely that the thigh-to-trunk ratio, which may limit the ability to achieve a full front squat, is significantly less than 1 when a trunk angle greater than 60 degrees is used. Furthermore, anterior knee translation initiated through rotation of the shank appears to be a strategy to maintain equilibrium at the end ranges of the front squat movement. It appears plausible that horizontal knee motion up to 5 cm past the vertical projection of the toes may allow athletes with large thigh-to-trunk ratios to reach full front squat depth and perhaps reduce loading on the low back. Additionally, ankle inflexibility may limit front squat depth.

No description available.

No description available.

From previous research, it has been proven that rock roughness and closure are two important factors for stability of backfilled stope and exposed backfill. In order to estimate the important parameters of roughness, several investigations have been conducted in other scientific fields to study roughness. The results showed that the important roughness parameters are application-dependent. In geology and rock mechanics the Joint Roughness Coefficient (JRC) is a critical factor that incorporates the roughness in stability problems. Although JRC is widely used, it is very subjective and highly depends on the experience of the individual conducting the analysis. During the last several decades there were attempts to use different methods such as fractal geometry, Fourier analysis, analytical methods, etc. to convert a random surface profile into a JRC. The goal of the current research is to estimate with greater accuracy the contribution of roughness to the shear strength of the interface at the paste-rock contact when backfilling. Four hundred and fifty backfill samples were constructed and tested in a shear box. The variables of the tests are three: binder percentage, roughness and cure time. From the test results the importance of each of those parameters to the final shear strength of the paste-rock interface was estimated. The normal stress that acts on the samples is also a critical factor. From the tests that were tried, it was concluded that there are limits in normal stress for which roughness is important. / Thesis (Master, Mining Engineering) -- Queen's University, 2009-08-27 16:07:21.916

No description available.

Thesis (M.Tech.: Chiropractic)--Durban University of Technology, 2008 / The core stability, club head velocity and ball carry in golfers with and without low back pain – a comparative study. Objective: The aims of this study was to establish whether an observable difference exists in the abdominal core stability of two comparable groups of golfers: one asymptomatic and the other suffering from low back pain, and whether an observable reduction of performance, expressed as club head velocity and ball carry can be observed in those with low back pain. First Objective was to differentiate the groups at baseline with respect to core stability strength between asymptomatic golfers and golfers suffering from low back pain. Whereas the Second Objective was to establish whether a relationship exists between abdominal core stability, CHV and ball carry in the two population groups under study. Following the above the Third Objective was to establish which other factors besides core stability strength have an effect on CHV and ball carry. And lastly the Fourth Objective was to establish the correlation between CHV and ball carry. Design: A comparative study was carried out between the two sample groups. A sample of forty patients were selected for this study, where twenty patients were asymptomatic and had no current episode of low back pain and were able to maintain a core contraction; and the other twenty patients low back pain and could not maintain a core contraction. Because the patients presented in a random manner, the patients were matched as close as possible according to age, so as to have better comparative value between the groups (the maximum age difference of a year was instituted). This allowed for comparisons among similar ages, with the difference being their low back pain and core contraction status. Outcome Measure: Each golfer was required to hit 5 balls using a standard club (in this study, a standard driver was used), after which an average value v was calculated for CHV and ball carry. All measurements were carried out using the Flightscope Pro machine at the Durban Pro Shop. Results: Core stability and low back pain did not influence CHV. However there was a non significant trend which indicated higher ball carry in the group with better core stability and no low back pain than in the group with low back pain and poor core stability. Increasing age and handicap reduced the CHV and ball carry values significantly. Ball carry and CHV were positively correlated together in both groups.

Currently Dual energy X-ray Absorptiometry (DXA) and Quantitative Ultrasound (QUS) are used readily in the clinical environment for the assessment of bone quality. However, neither measure is a direct mechanical measure of bone. A Mechanical Resonance Tissue Analyzer (MRTA) has been developed that looks at the ulna’s deformation curve to vibration to achieve the measure of EI, cross sectional bending stiffness. This study investigated the relationships between MRTA to that of QUS and DXA. Regression analysis found significant linear correlations between EI to BMD and BMC, however, no significant relationships were found between EI and the variables of QUS. However, this technology is seen to have a potential for the assessment of in vivo bone quality. Furthermore, an improved configuration of the MRTA device is described, in addition to how preliminary results correspond to theoretical results.