Abstract Stretching exercises are commonly used as an integral part of a pre-exercise warm-up training sessions despite even early laboratory studies having demonstrated that some degree of mechanical weakness takes place following the stretching of muscle tissue. This study compared the effects of four treatments (n = 12 each) [10 minutes of quiet sitting, without stretching (NS); two minutes warm up on an arm ergometer at 25 watts resistance (WU); 10 second-hold static stretching (each) of the shoulder, chest and arm muscle groups (ST10); and two sets of 20 second-hold static stretching (each) of the shoulder, chest and upper-arm muscle groups (ST20)] on a 1-RM bench press in 48 subjects who were matched for their pre-test 1-RM bench press values. The mean 1-RM bench press values following ST10 (45.0 ± 9.9 kg) and WU (48.9 ± 10.5 kg) treatments were significantly (p ? 0.05) higher at the post-test than at the pre-test 1-RM (43.9 ± 10.1 kg and 43.9 ± 10. kg, respectively). The mean 1-RM values following the ST20 treatment was significantly lower (41.9 ± 10.0 kg) than at pre-test (43.9 ± 10.1 kg). However, multiple comparisons and Analysis of Variance (ANOVA) statistical procedures demonstrated that there was no significant difference from pre- to post-test between the four groups. These findings suggest that the use of stretching activities prior to events requiring maximal force production may not be obligatory or may even be contraindicated since the effects of stretching are then to decrease the amount of force that can be produced via the natural elastic components of the muscle and tendons and via the stretch reflex.

The use of a counter-balance weight system of a Smith machine affects measures of bench press throw performance. Twenty-four men performed bench press throws at 30% of their one-repetition maximum under four different conditions: 1) counter-balance and rebound movement (RC), 2) no counter-balance and rebound movement (RNC), 3) counter-balance and concentric only movement (CC), and 4) no counter-balance and concentric only movement (CNC). Peak power, force, and concentric and eccentric velocities were measured using a linear accelerometer; and peak ground reaction force (GRF) was measured using a forceplate. Peak measures for concentric and eccentric velocities showed that NCB> CB and RBT > CBT. Peak GRF measures showed CB > NCB and RBT > CBT. The lower performance measures for CB were likely due to an increase in the net external load when the barbell accelerates faster than the gravitational constant causing the counter-balance weight becomes ineffective.

No description available.

Spoil pile stability in an open pit coal mine is a common problem and the Red Hills Lignite Mine in Choctaw County is no exception. The mine has had spoil stability problems of their spoil dragline bench since the beginning of their activity in 2002. They have managed to stabilize the conditions by installing prefabricated vertical drains (PVD) to consolidate the layers below the spoil dragline bench, which tended to fail due to an increase in pore water pressure. In this study, the capability of analyzing and predicting future pore water pressure conditions is examined. With the use of the stability model Slope/w and local stress calculations, the predictability of the necessity of PVDs and their spatial distribution are analyzed. The outcomes prove to be circumstantial to local pore water pressure and geology changes, therefore, the spacing between drains could be adapted to the local conditions potentially saving costs.

To examine differences in body composition and maximal strength between collegiate (CLG) and men's club (CLB) rugby union players, as well as between the forward (FW) and back (BK) positions, seventeen resistance-trained men (24 ± 2.4 yrs; range: 20 ± 27 yrs; 179.3 ± 5.4 cm; 93.7 ± 12.9kg) from a collegiate rugby team (n=11) and a local men's rugby club (n=6) were recruited to participate in the present investigation. Prior to strength testing, height (± 0.1 cm), body mass (± 0.1 kg), and body composition via dual energy x-ray absorptiometry were assessed to determine total percent body fat (%FAT), lean body mass (LBM), lean arm mass (LAM), and lean leg mass (LLM). Maximal upper- and lower-body strength were determined from each participant's one-repetition maximum (1RM) in the bench press and squat, respectively. Additionally, athletic history, resistance training experience, and distractors (e.g. work, school, and sleep) were determined via questionnaire. Significant (p<0.05) differences were observed between clubs in age (CLG: 22.3 ± 1.3y; CLB: 26.2 ± 1.1y), years played (CLG: 2.9 ± 2.4y; CLB: 7.5 ± 2.1y), and starting experience (CLG: 1.7 ± 2.6y; CLB: 5.2 ± 3.4y). In terms of position, LAM was significantly (p = 0.037) greater in FW (10.6 ± 1.7kg) than in BK (9.0 ± 0.5kg). These findings suggest rugby union players possess similar strength and size characteristics, regardless of age, playing experience, or position.

Generation of test benches for large DSP behavioral models is a complicated, labor intensive task. Also, tests generated manually satisfy no formal definition of completeness. To address these needs, high level approaches to test bench development are employed which relieve the modeler of the details of test bench development. Two approaches being explored are: 1) behavioral - the CASE tools develop complete high level models of the test bench, and 2) structural- a library of primitive components is developed so that a conventional schematic capture tool, e.g., Synopsys Graphical Environment, can be used to construct the test bench. An intelligent interface prompts the user for high level test bench information, and inserts this information into the test bench code. The intelligent interface also allows the user to specify and control file I/O as a data source. The objective of this thesis is the development of a set of library models from which a structural test bench can be created. This thesis also describes creation of the structural test bench using the library of primitive components and Synopsys Graphical Environment, a conventional schematic capture tool. This approach has been implemented for two applications: 1) A 2D Image processing algorithm - InfraRed Search and Track (IRST) and 2) Synthetic Aperture Radar (SAR). An intelligent interface developed in C combines the structural model with user information which provides for generics and inputs. This thesis also shows how a requirements capture tool can be used to generate generic values. / Master of Science

Faculty of Engineering and Built Enviroment School of Mining Engineering 0315711f musakale@egoli.min.wits.ac.za / Rockfalls are a significant risk in open pit mines. Once movement of a rock perched on the top of a slope (bench) has been initiated, the most important factor controlling its fall trajectory is the geometry of the slope (bench). The best possible knowledge of rockfall trajectories and energies is important in order to determine accurate risk zoning and for the design and construction of adequate defence systems near the threatened areas. This study attempts to determine the influence of bench geometries, and the coefficient of restitution of rock, on rockfall behaviour. A study of literature was carried out to review previous studies and other relevant information on rockfalls and their analysis. The literature may be divided into two categories: experimental methods involving physical modelling, and computer models involving rockfall analyses using computers analysis methods. Rockfall computer simulation is considered to be applicable, quick to carry out and reproducible. The accuracy of the results depends on the knowledge of site conditions and slope geometry. The use of the Modified Ritchie criterion for the design of catch benches in open pit mines was also investigated. The assessment of bounce height, maximum run-out distance and kinetic energy achieved during the fall of rocks on the catch bench were the bases of the evaluation of the results obtained in this project. The computer program, Rocfall Version 4, was used for the purposes of the research. The following parameter variables were considered in the analyses: three types of rock; slopes with three stack configurations; four bench heights; and four bench face angles. The results show that, for all stack configurations and rock types, the maximum runout distance and maximum bounce height increase as functions of bench height at a specific bench face angle. A single bench configuration provides a maximum run-out distance of falling rocks larger than the value determined using the Modified Ritchie criterion for all rock types and bench face angles. Multiple bench stack configurations provide maximum run-out distances less than the value determined using the Modified Ritchie criterion only for the 90o bench face angle in all rock types; those with 60o, 70o and 80o bench face angle provide a larger maximum run-out distance. Therefore, the validity of the Modified Ritchie criterion for the design of catch bench widths in open pit mines with inclined benches must be questioned. According to Ritchie’s study (1963), rocks that fall in trajectory (free fall) seldom give high bounces after impact on a catch bench. This project shows that this finding is valid for rocks with low coefficients of normal restitution. Rocks with lower coefficients of normal restitution provide larger run-out distances with flatter bench face angles compared with rocks with higher coefficients. In contrast, rocks with higher coefficients provide larger run-out distances than those with lower coefficients for steeper angles. The consideration of the influence of geometry (shape) of falling rocks on rockfall behaviour showed that, for a flatter slope, as could logically be expected, the maximum run-out distance is greatest for rounder rocks and smallest for flatter slabby iv rocks. This is due to the fact that on a flatter slope, the mode of falling of rounder rocks is rolling down the slope. This mode provides essentially no resistance to motion, resulting in largest maximum run-out distance. In contrast, for long flat slabs, the mode of movement will be sliding, which results in a smaller maximum run-out distance. The maximum run-out distance as function of rock shape reduces as the normal coefficient of restitution increases. For all rock types, the maximum bounce height reduces as a function of the friction angle for flatter slopes. This is due to the fact that rocks are in contact with the slope during the rockfall. As the coefficient of normal restitution increases, an increase in the maximum bounce height results.

No description available.

A laboratory-scale upflow anaerobic sludge blanket (UASB) reactor followed by a packed bed reactor (PBR) filled with Sorbulite® in the lower part and Polonite® in the upper part was used to treat household wastewater in a 50-week experiment. A model was developed to describe the performance of the UASB reactor, including mass transfer through the film around anaerobic granules, intra-particle diffusion and bioconversion of the substrate. In a second model, a numerical expression describing the kinetics occurring in the granules was developed. It includes the resistances through which the substrate passes before biotransformation. These expressions were then linked to governing equations for the UASB reactor in order to describe degradation of the substrate, biomass growth (active and inactive), and variation in granule size over time. A third model was developed to describe the profile of the phosphorus (P) concentration throughout the PBR. In a first attempt, the analytical and numerical model was applied to data taken from previous studies in which UASB reactors were used to treat sugarcane mill wastewater and slaughterhouse wastewater. The results showed good agreement between observed and simulated results. Sensitivity analysis showed that diffusion coefficient and yield were important parameters in the UASB reactor model.The laboratory bench-scale experiment revealed that the combined UASB-PBR system efficiently treated the residential wastewater. Phosphorus, BOD7 and pathogenic bacteria all showed average removal of 99%, while total nitrogen showed a moderate reduction in the system (40%). Application of the numerical solution model to the experimental UASB reactor used resulted in good agreement between simulated and experimental values. Regarding the PBR, the model developed successfully predicted P removal. For both models, the capability and sensitivity analyses identified important parameters. A treatment system aiming to close the loop is suggested based on sequential UASB and PBR with biogas collection, nutrient recycling via sludge and filter media and elimination of pathogenic organisms. / <p>QC 20160226</p>

Two different weight training programs were compared to determine which was most effective in improving strength. The experiment was conducted with the bench press, leg press, and sitting press for a period of fifteen weeks.