Since the identification, in the UK, of the need for further information on the dynamic loading of grandstands in the early 1990s, a number of research projects have investigated the issues relating to dynamic loading of structures due to groups of people participating in synchronised activities. These studies have, to date, largely focused on producing load models to accurately represent the dynamic crowd load and the human-structure interaction. However, whilst the vibrational response of grandstand structures is becoming better understood, the question arises as to what level of dynamic response is acceptable to the users. Currently there is very little experimental data available regarding human perception of vibrations in such crowd loading situations. As a result those producing design standards and design guides have very little information on which to base serviceability requirements. To address this, tests have been carried out at the University of Bath using a section of grandstand, whose dynamic properties could be varied, with the aim of developing acceptability criteria. Groups of participants were subjected to a range of vibrations induced by selected members of the group jumping in synchrony. Both those seated and jumping during the tests were asked to rate their perception and emotion of each vibration as well as the acceptability of the vibration in a real grandstand situation. These ratings were then used to statistically model perception and emotion to find the key vibration characteristics influencing the human response of both the seated and jumping participants prior to developing acceptability curves for each group. It was found that those seated are more sensitive to vibrations than those jumping to create them. The response of the jumpers is relatively simple and can be fairly accurately modelled using just a single variable namely the square of vertical RMS displacement. The seated response is much more complex but can be relatively accurately represented using logarithm of vertical RMS acceleration. The proposed acceptability criteria and load model generally tie in well with previously published guidelines provided that the serviceability criteria are in the same format as the original research upon which they were based (i.e. peak accelerations).

The following results were obtained in the presented thesis: 1. Based on a previous work on the MoM method, a software modulus was created and tested in MATLAB, which solves a small-size scanning metal array with arbitrary element position and arbitrary lumped loading. 2. The solver was applied to optimize a broadband planar array of dipoles using the concept of negative lumped loading, which was introduced by R.C. Hansen in 2003. The problem statement was formulated by E. Kratzenberg of MIT Haystack Observatory. 3. The optimization implies full testing of varied array configurations with different element numbers, dipole thicknesses, generator impedances, and lumped loading values. 4. The results obtained indicate that that both 4x4 and 6x6 arrays of dipoles may be optimized over the frequency band from 50 to 300 MHz. The optimization means that the Scan Element Pattern of the array at zenith nearly follows the theoretical limit (area gain per element).

Modelos constitutivos são relações matemáticas entre grandezas físicas que buscam descrever o comportamento dos materiais quando submetidos a ações externas. A hipoplasticidade é um modelo constitutivo desenvolvido para solos a partir de uma modificação da equação hipoelástica. Este modelo tem como principais características a existência de uma única equação constitutiva e o seu caráter não linear, o que lhe confere a propriedade de introduzir deformações irreversíveis desde o início das ações externas. Neste trabalho são estudados dois novos modelos desenvolvidos com o objetivo de melhorar as previsões para carregamentos cíclicos. O primeiro, denominado hipoplasticidade estendida, é caracterizado pela introdução de superfícies de memória e uma nova equação constitutiva específica para o recarregamento. O segundo modelo, a hipoplasticidade cíclica, é uma modificação deste último onde são introduzidos fatores capazes de modificar as superfícies de memória. Os novos modelos são primeiramente aplicados em situações teóricas para verificar sua aplicabilidade. Posteriormente, utilizando dados experimentais, é feita sua calibração e aplicação para então compararem-se as previsões teóricas com os resultados experimentais. Verifica-se que os novos modelos contemplam avanços significativos na previsão do comportamento dos solos sob carregamentos cíclicos. Para permitir um número maior de simulações foi desenvolvida uma planilha eletrônica com a capacidade de representar quantos ciclos sejam desejados, efetuar a alteração dos parâmetros do solo durante a calibração do modelo de maneira fácil e rápida, assim como visualizar para cada um dos intervalos se foi utilizada a equação geral ou a específica do recarregamento. / Constitutive models are mathematical relationships between physical quantities that approximate the behavior of materials when subjected to external actions. Hypoplasticity is a constitutive model developed for soils from a modification of the hypoelastic equation. The main features of this model are the existence of a unique constitutive equation and its nonlinear character, which gives it the property of introducing irreversible deformation from the beginning of external actions. In this work two new models developed in order to improve the predictions of cyclic loading are studied. The first one, which is called extended hypoplacity, has as its main feature the addition of a memory surface and the introduction of a new equation specific for reloading. The second model, cyclic hypoplasticity, which is a modification of this last one, is characterized by the introduction of factors that are capable of modifing the memory surfaces. The new models are first checked in theoretical situations to verify their applicability. Subsequently, using experimental data, the models are calibrated, applied, and then compared to experimental results. The new models include significant advances in predicting soil behavior under cyclic loading. To allow a larger number of simulations, a spreadsheet was developed with the following abilities: simulate as many cycles as are desired; easy to change soil\'s parameters during the calibration phase; and display for each of the intervals which of the equations was used.

abstract: The lifetime of a transformer is essentially determined by the life of its insulation system which is a time function of the temperature defined by its thermal class. A large quantity of studies and international standards have been published indicating the possibility of increasing the thermal class of cellulose based materials when immersed in natural esters which are superior to traditional mineral oils. Thus, a transformer having thermally upgraded Kraft paper and natural ester dielectric fluid can be classified as a high temperature insulation system. Such a transformer can also operate at temperatures 20C higher than its mineral oil equivalent, holding additional loading capability without losing life expectancy. This thesis focuses on evaluating the use of this feature as an additional capability for enhancing the loadability and/or extending the life of the distribution transformers for the Phoenix based utility - SRP using FR3 brand natural ester dielectric fluid. Initially, different transformer design options to use this additional loadability are compared allowing utilities to select an optimal FR3 filled transformer design for their application. Yearlong load profiles for SRP distribution transformers, sized conventionally on peak load demands, are analyzed for their oil temperatures, winding temperatures and loss of insulation life. It is observed that these load profiles can be classified into two types: 1) Type-1 profiles with high peak and high average loads, and 2) Type-2 profiles with comparatively low peak and low average load. For the Type 1 load profiles, use of FR3 natural ester fluid with the same nominal rating showed 7.4 times longer life expectation. For the Type 2 load profiles, a new way of sizing ester filled transformers based on both average and peak load, instead of only peak load, called “Sustainable Peak Loading” showed smaller size transformers can handle the same yearly peak loads while maintaining superior insulation lifespan. It is additionally possible to have reduction in the total energy dissipation over the year. A net present value cost savings up to US$1200 per transformer quantifying benefits of the life extension and the total ownership cost savings up to 30% for sustainable peak loading showed SRP distribution transformers can gain substantial economic savings when the distribution transformer fleet is replaced with FR3 ester filled units. / Dissertation/Thesis / Envirotemp FR3 Fluid Brochure / Envirotempe FR3 Fluid Data Sheet / Masters Thesis Electrical Engineering 2018

Accentuated eccentric loading (AEL) prescribes eccentric load magnitude in excess of the concentric prescription using movements that require coupled eccentric and concentric actions, with minimal interruption to natural mechanics. This method has been theorized to potentiate concentric performance through higher eccentric loading and, thus, higher concentric force production. There is also evidence for favorable chronic adaptations, namely shifts to faster myosin heavy chain isoforms and changes in IIx-specific muscle cross-sectional area. However, research concerning the acute and chronic responses to AEL is inconclusive, likely due to inconsistencies in subjects, exercise selection, load prescription, and method of providing AEL. Therefore, the purpose of this review is to summarize: (1) the magnitudes and methods of AEL application; (2) the acute and chronic implications of AEL as a means to enhance force production; (3) the potential mechanisms by which AEL enhances acute and chronic performance; and (4) the limitations of current research and the potential for future study.

It has been suggested that simulating physiological loading of the knee during magnetic resonance imaging (MRI) is a promising technique for assessing soft and hard tissues in the knee joint. We have developed a novel MRI-compatible lower limb loading and positioning device to assess knee biomechanics in a physiologically relevant environment using MRI. The objectives of this study were (1) to evaluate inter- and intra-examiner reliability for using our custom-built loading system to maintain a desired load magnitude and direction during each loading trial and over repeated subject visits and (2) to determine the effect of the applied load on motion of the subject's knee over the duration of a loading trial. The pneumatic-controlled loading system was tested on ten subjects at a compression load of 50% of the subject's bodyweight. Two examiners separately positioned and loaded each subject for three loading trials per visit, repeated for three visits. The primary outcome measure was the magnitude of the primary axial load (proximal/distal force) applied to the subject's foot over a loading trial. Secondary outcome measures included average magnitude of medial/lateral and anterior/posterior forces as well as valgus/varus, flexion/extension, and external/internal moments applied to the subject's foot during a loading trial. Location of center of loading at the foot was also recorded. Primary axial load was found to be maintained to within 44-47% of subject bodyweight. Following load-application, the subject's knee exhibited movement throughout the duration of each loading trial. We found that 61.0% of proximal/distal knee displacement occurred within the first 2 minutes following loading. Between minutes 4 and 12, knee positioning was maintained to within 0.92 mm in the medial/lateral direction and 1.24 mm in the proximal/distal direction. We conclude that our loading device can apply controllable and reproducible loading over repeated trials as well as limit subject motion throughout each trial.

PURPOSE: To understand the influences of mechanical loading on bone adaptation, the ground reaction force (GRF) applied to the bone must be quantified. The use of force plates in a lab setting is the accepted method for quantifying GRFs; however, this is not feasible in free-living situations. Recent developments in accelerometer technology may provide the ability to evaluate the effects of mechanical loading on bone outside of laboratory settings. The purpose of this project was to validate an accelerometer for the measurement of mechanical loading by comparing its output against GRFs. METHODS: Male and female participants (n = 20 males, 20 females; 18 to 49 yr) completed 10 repetitions of 9 common everyday movements (stand, walk, jog, run, 15 cm jump, step down from curb, drop down from curb, forward hop, and side hop) on a force plate with an accelerometer worn on their right hip. Then, a subset (n = 5 males, 5 females) wore an accelerometer on their right hip and played basketball, volleyball, and dodgeball as a group. Finally, all 40 participants wore an accelerometer home for 7 days. All activities were organized into derived activity categories labeled as low-, moderate-, and high-mechanical-load-intensity and used with 59 possible accelerometer variables to predict mechanical load. Models were fit using the randomForest package in R. Model performance (coefficient of determination [R2] and median absolute error) was evaluated using cross-validation. RESULTS: The percentage of variation mechanical load intensity explained by the models ranged from 0.27 to 0.78 with median absolute errors ranging from 0.20 to 0.49. The model with R2 = 0.78 contained the known activity categories and the accelerometer variables, but this is not realistic for free-living situations where activity categories will not be known. The two free-living models with the highest R2 values included derived activity categories and accelerometer variables, and estimated, on average, 21.1 and 20.7 hours per day in low-intensity, 1.6 and 1.7 hours per day in moderate-intensity, and 0.0 and 0.5 hours per day in high-intensity osteogenic activity, respectively. CONCLUSION: It is assumed that higher intensity activities (i.e., jumping vs. jogging) result in higher GRF values, but depending on the actual execution of the movement, this is not always the case. This research demonstrated that models containing the accelerometer variables performed better in predicting GRF than those containing only the derived activity categories. This supports the hypothesis that accelerometers provide valuable objective information when evaluating mechanical loading on bone.

Nitrate (NO3) loadings from stormwater runoff promote eutrophication in surface waters. Low Impact Development (LID) is a type of best management practice aimed at restoring the hydrologic function of watersheds and removing contaminants before they are discharged into ground and surface waters. Also known as rain gardens, a bioretention system is a LID technology that is capable of increasing infliltration, reducing runoff rates and removing pollutants. They can be planted with visually appealing vegetation, which plays a role in nutrient uptake. A modified bioretention system incorporates a submerged internal water storage zone (IWSZ) that includes an electron donor to support denitrification. Modified (or denitrifying) bioretention systems have been shown to be capable of converting NO3 in stormwater runoff to nitrogen gas through denitrification; however, design guidelines are lacking for these systems, particularly under Florida-specific hydrologic conditions. The experimental portion of this research investigated the performance of denitrifying bioretention systems with varying IWSZ medium types, IWSZ depths, hydraulic loading rates and antecedent dry conditions (ADCs). Microcosm studies were performed to compare denitrification rates using wood chips, gravel, sand, and mixtures of wood chips with sand or gravel media. The microcosm study revealed that carbon-containing media, acclimated media and lower initial dissolved oxygen concentrations will enhance NO3 removal rates. The gravel-wood medium was observed to have high NO3 removal rates and low final dissolved organic carbon concentrations compared to the other media types. The gravel-wood medium was selected for subsequent storm event and tracer studies, which incorporated three completely submerged columns with varying depths. Even though the columns were operated under equivalent detention times, greater NO3 removal efficiencies were observed in the taller compared to the shorter columns. Tracer studies revealed this phenomenon was attributed to the improved hydraulic performance in the taller compared to shorter columns. In addition, greater NO3 removal efficiencies were observed with an increase in ADCs, where ADCs were positively correlated with dissolved organic carbon concentrations. Data from the experimental portion of this study, additional hydraulic modeling development for the unsaturated layer and unsaturated layer data from other studies were combined to create nitrogen loading model for modified bioretention systems. The processes incorporated into the IWSZ model include denitrification, dispersion, organic media hydrolysis, oxygen inhibition, bio-available organic carbon limitation and Total Kjeldahl Nitrogen (TKN) leaching. For the hydraulic component, a unifying equation was developed to approximate unsaturated and saturated flow rates. The hydraulic modeling results indicate that during ADCs, greater storage capacities are available in taller compared to shorter IWSZs Data from another study was used to develop a pseudo-nitrification model for the unsaturated layer. A hypothetical case study was then conducted with SWMM-5 software to evaluate nitrogen loadings from various modified bioretention system designs that have equal IWSZ volumes. The results indicate that bioretention systems with taller IWSZs remove greater NO3 loadings, which was likely due to the greater hydraulic performance in the taller compared to shorter IWSZ designs. However, the systems with the shorter IWSZs removed greater TKN and total nitrogen loadings due to the larger unsaturated layer volumes in the shorter IWSZ designs.

Scientific databases often need to be accessed from a variety of different applications. There are usually many ways to retrieve and analyse data already in a database. However, it can be more difficult to enter data which has originally been stored in different sources and formats (e.g. spreadsheets, other databases, statistical packages). This project focuses on investigating a generic, platform independent way to simplify the loading of databases. The proposed solution uses Web services as middleware to supply essential data management functionality such as inserting, updating, deleting and retrieval of data. These functions allow application developers to easily customise their own data entry applications according to local data sources, formats and user requirements. We implemented a Web service to support loading data to the Germinate database at the New Zealand Institute of Crop & Food Research (CFR). We also provided language specific client toolkits to help developers invoke the Web service. The toolkits allow applications to be easily customised for different platforms. In addition, we developed sample applications to help end users load data from their project data sources via the Web service. The Web service approach was evaluated through user and developer trials. The feedback from the developer trial showed that using Web services as middleware is a useful approach to allow developers and competent end users to customise data entry with minimal effort. More importantly, the customised client applications enabled end users to load data directly from their project spreadsheets and databases. It significantly reduced the effort required for exporting or transforming the source data.

Thesis (M. Phil.)--University of Hong Kong, 2007. / Title proper from title frame. Also available in printed format.