Power-generating capacity should be a primary training outcome for football athletes. The ability to be explosive and use high levels of strength seems to differentiate between athletes and teams. Developing training interventions that can improve both strength- and power-generating capacity would therefore be considered a paramount endeavor when attempting to optimize the physiological and performance adaptations necessary for competitive success. Too often, strength and conditioning coaches forget that the foundation of powergenerating capacity is in fact high levels of muscular strength. When the development of strength is minimized or excluded from the training plan, the ability to express high-power outputs is compromised. In addition, a failure to use sequenced and integrated training programs decreases the possibility of successfully increasing strength- and power-generating capacity, thus decreasing the potential for competitive success. Therefore, this brief review attempts to explain how strength- and powergenerating capacity can be enhanced to increase the potential for developing the physiological and performance foundation necessary for competitive success with the football athlete.

The following dissertation introduces the hazard of methane buildup in the gob zone, a caved region behind a retreating longwall face. This region serves as a reservoir for methane that can bleed into the mine workings. As this methane mixes with air delivered to the longwall panel, explosive concentrations of methane will be reached. Computational fluid dynamics (CFD) is one of the many approaches to study the gob environment. Several studies in the past have researched this topic and a general approach has been developed that addresses much of the complexity of the problem. The topic of research herein presents an improvement to the method developed by others. This dissertation details a multi-scale approach that includes the entire mine ventilation network in the computational domain. This allows one to describe these transient, difficult to describe boundaries. The gob region was represented in a conventional CFD model using techniques consistent with past efforts. The boundary conditions, however, were cross coupled with a transient network model of the balance of the ventilation airways. This allows the simulation of complex, time dependent boundary conditions for the model of the gob, including the influence of the mine ventilation system (MVS). The scenario modeled in this dissertation was a property in south western Pennsylvania, working in the Pittsburgh seam. A calibrated ventilation model was available as a result of a ventilation survey and tracer gas study conducted by NIOSH. The permeability distribution within the gob was based upon FLAC3d modeling results drawn from the literature. Using the multi-scale approach, a total of 22 kilometers of entryway were included in the computational domain, in addition to the three dimensional model of the gob. The steady state solution to the problem, modeling using this multi-scale approach, was validated against the results from the calibrated ventilation model. Close agreement between the two models was observed, with an average percent difference of less than two percent observed at points scattered throughout the MVS. Transient scenarios, including roof falls at key points in the MVS, were modeling to illustrate the impact on the gob environment.

Title: Velocity characteristics of soccer players Objectives: The main goal of the thesis id to evaluate and analyze velocity and agility abilities of elite players. Analyze the change direction in velocity in the form of acceleration and deceleration turn over to the opposite direction. Compare the movement task session to the right and left rotating lower limb. Methods: Measured group consisted of 35 players with these athropometric values (age = 20±3,25 years, height = 187 ± 0,648 m, weight = 72 ± 3.25 kg). Players completed the warm-up prior to testing (activation stretching, stretching, warm up and subsequent motion game). Measured tested portion was 5m, followed by turning on the predefined leg and running backwards to the photocell gate (test 505). Each player completed 2 attemps on the right and 2 attemps on the left leg. Method for evaluating the kinematics used 2D video analysis. For video processing software was used Bio TEMA (ImageSystems Ltd., Sweden). Results: Players in test of velocity achieved different times on rotation right and left side. However these differences were not significant. In the first step of slowing and accelerating players do not reach comparable velocity. They can compare velocity on the second step. On right side players will use the stride length at step 2 and...

There is an increase in bombing assaults in recent years in our country. Determining the explosive material used in these cases by the quick and correct analysis of the evidence obtained after the explosions, is an important starting point for the investigations which are done to reach the perpetrators. The forensic chemistry investigations have to be correct, exact and rapid in order to reach the right criminal. In this study, the Gas Chromatography-Mass Spectrometry (GC-MS) and Gas Chromatography-Thermal Energy Analyser (GC-TEA) methods which are being used for the determination of the explosive materials&rsquo / residues used in bombing attacks are optimized with the standard solutions of 2,4,6-Trinitrotoluene (TNT) and 1,3,5-trinitro-1,3,5-triazocyclohexane (RDX) and standard mixture solution. The two methods were compared by analysing the postexplosion soil samples. Also an efficient and applicable sample preparation procedure was developed. The results showed that both methods are efficient and sensitive for the postexplosion investigations. It is seen that GC-TEA has lower detection limit and simple chromatograms due to its selectivity against only nitro group containing explosives. However it is concluded that there is a need for a reliable and sensitive method like GC-MS which provides identification and library search, for the determination of the organic components which can not be identified with GC-TEA

Reinforced concrete structures may be subjected to blast loads together with static loads during their service life. Important buildings may be attacked by using explosives as a part of increasing global terrorist activities. Evaluation of blast phenomena for economically and strategically significant buildings is especially important, in order to analyze and design their structural members subjected to air blast loading. Understanding nature of explosions, which are loading characteristics and relation to selected parameters such as explosive type, quantity, and distance, were studied in this thesis. Earlier studies found in the literature survey on explosives, blast, and behavior of structural elements were investigated. Behavior of structures under blast load was described in terms of pressure magnitude, distribution, and reflection phenomena. Simple design, assessment guidelines, and useful charts were developed. A computer program was generated using MATLAB programming language, which automatically generates the air blast pressure versus time data resulting from an air explosion in addition to finite element model formation and dynamic time stepping analysis of a reinforced concrete column. The shear and moment capacities can be calculated and compared against dynamically calculated demand under known axial column force / therefore, vulnerability of a column under blast loading is evaluated. The results of the numerical analyses indicated that failure mechanism of columns is mostly shear failure instead of moment (i.e., plastic hinge and mechanism formation).

This dissertation focuses on developing a predictive method for determining the dynamic densification behavior of thermite powder mixtures consisting of equivolumetric mixtures of Ta + Fe₂O₃ and Ta + Bi₂O₃. Of primary importance to these highly reactive powder mixtures is the ability to characterize the stress at which full compaction occurs, the crush strength, which can significantly influence the stress required to initiate reaction during dynamic or impact loading. Examined specifically are the quasi-static and dynamic compaction responses of these mixtures. Experimentally obtained compaction responses in the quasi-static regime are analyzed using available compaction models, and an analysis technique is developed that allows for a correct measurement of the apparent yield strength of the powder mixtures. The correctly determined apparent yield strength is combined with an equation of state to yield a prediction of the shock densification response, including the dynamic crush strength of the thermite powder mixtures. The validated approach is also extended to the Al + Fe₂O₃ thermite system. It is found that accurate predictions of the crush strength can be obtained through determination of the apparent yield strength of the powder mixture when incorporated into the equation of state. It is observed that the predictive ability in the incomplete compaction region is configurationally dependent for highly heterogeneous thermite powder systems, which is in turn influenced by particle morphology and differences in intrinsic properties of constituents (density, strength, etc.).

Eruption dynamics are sensitive to ash aggregation, and ash aggregates (e.g. accretionary lapilli) are commonly found in eruptive deposits, yet few experiments have been conducted on aggregation phenomena using natural materials. Experiments were developed to produce a probabilistic relationship for the efficiency of ash aggregation with respect to particle size, collision kinetic energy and atmospheric water vapor. The laboratory experiments were carried out in an enclosed tank designed to allow for the control of atmospheric water vapor. A synthetic ash proxy, ballotini, and ash from the 2006 eruption of Tungurahua, in Ecuador, were examined for their aggregation potential. Image data was recorded with a high speed camera and post-processed to determine the number of collisions, energy of collisions and probability of aggregation. Aggregation efficiency was dominantly controlled by collision kinetic energy and little to no dependence on atmospheric water vapor was seen in the range of relative humidity conditions tested, 20 to 80%. Equations governing the relationships between aggregation efficiency and collision kinetic energy and the related particle Stokes number, respectively, were determined for implementation into large scale numerical volcanic models.

Thesis (M.S.)--Naval Postgraduate School, 2002. / Thesis advisor(s): John E. Mutty, Joseph G. San Miguel. Includes bibliographical references (p. 59-61). Also available online.

Thesis (M.S.)--Naval Postgraduate School, 2002. / Title from title screen (viewed July 18, 2003). Includes bibliographical references (p. 59-61). Also issued in paper format.

Xenoliths preserve evidence of magma-crust interactions in magmatic reservoirs and conduits. They reveal processes of partial melting of country rock, and disintegration into magma. Widespread evidence for frothy xenoliths in volcanic deposits exists, and these evidently indicate processes of gas liberation, bubble nucleation and bubble growth. This report focuses on textural analysis of frothy sandstone xenoliths from Krakatau in Indonesia, Cerro Negro in Nicaragua, Cerro Quemado in El Salvador and from Gran Canaria, Canary Islands, and involves attempts to experimentally reproduce xenolith textures. To achieve this, magmatic conditions acting upon country rock in volcanoes are simulated by subjecting sandstones to elevated temperature and pressure in closed system-autoclaves. Subsequent decompression imitates magma ascent following xenolith entrainment, and is largely responsible for the formation of frothy xenolith textures. The experiments show a range of successive features, such as partial melting, gas-pressure build up, bubble nucleation, growth and development of bubble networks. The experiments closely reproduced textures of natural xenoliths and help to assess the controlling P-T parameters that encourage efficient bubble growth. Conditions proved ideal between 850˚C and 870˚C and pressure release from 1 kbar. Such conditions limit bubble overprinting by secondary crystallization and melt infilling. Country rock lithology proved vital regarding gas pressure build-up and resulting bubble nucleation during decompression. In particular, increased water content and relict crystals in the melt produced appear to ease and promote gas liberation by enabling early and effective bubble nucleation. Moreover, experiments confirm a decisive role for bubble coalescence. These results attest to the great potential of country rock to develop interconnected bubble networks upon magma contact, exsolving large amounts of crustal volatiles into the magma. Volatile input involves a change in magma viscosity and thus an accompanied change in disruptive behaviour, and may hence be responsible for increased potential to cause explosive volcanic eruptions. Moreover, H2O and CO2 vapour are severe greenhouse gases, which seems to be added to the atmosphere from crustal rocks via recycling by volcanic activity, and may have yet underappreciated effects on Earth’s climate.