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Ecophysiological responses of Litopenaeus vannamei were evaluated as functions of 1) salinity and animal size, 2) temperature and the animal's nutritive state, and 3) dissolved-oxygen concentration and animal size. Growth rate, routine metabolic rate, limiting oxygen concentration for routine metabolism, and marginal metabolic scope were determined for L. vannamei maintained and tested at salinities of 2, 10, and 28 ppt, all at 28 C. Routine metabolic rate (RMR) was not demonstrably dependent on salinity but decreased with increasing shrimp weight. Limiting oxygen concentration for routine metabolism (LOCr) was independent of shrimp weight up to 9 g; but, for larger shrimp, decreased with increasing weight. Marginal metabolic scope (MMS = RMR/LOCr) also decreased with increasing shrimp weight and was independent of salinity for shrimp weighing up to 9 g; but, like LOCr, MMS was dependent on salinity for larger shrimp. Growth rate was significantly less at 2 ppt than at 10 or 28 ppt, which gave similar growth rates. The effects of four temperatures (20, 24, 28, and 32 C) on growth, RMR, LOCr, and MMS were examined for fed and starved L. vannamei. Routine metabolic rate increased with increased temperature both for fed and starved shrimp. Marginal metabolic scope and growth appeared to be positively related and, at 20 C, seemed to induce a state of metabolic torpor. Data from the study of chronic effects of hypoxia (~2 mg O2 L-1) vs. normoxia (> 5 mg O2 L-1) on ecophysiological responses indicated that although low-DO environments can depress RMR and growth in L. vannamei, animals grown under hypoxic and normoxic conditions did not differ in their metabolic responses upon acute exposure to hypoxia, providing no evidence of acclimation to hypoxia in L. vannamei. Data from the above experiments were used to parameterize Ecophys.Shrimp, a computer simulation model of shrimp growth in time-varying environmental regimes. One unified model was able to simulate all my experiments; and, with only minimal adjustment of the model parameter MMSO, it also adequately simulated studies taken from the literature. Thus, Ecophys.Shrimp seems capable of realistically representing the ecophysiological dynamics of shrimp metabolism and growth in various culture systems.

With the recent widespread deployment of intelligent transportation systems (ITS) in North America there is an abundance of data on traffic systems and thus an opportunity to use these data in the calibration of microscopic traffic simulation models. Even though ITS data have been utilized to some extent in the calibration of microscopic traffic simulation models, efforts have focused on improving the quality of the calibration based on aggregate form of ITS data rather than disaggregate data. In addition, researchers have focused on identifying the parameters associated with car-following and lane-changing behavior models and their impacts on overall calibration performance. Therefore, the estimation of the Origin-Destination (OD) matrix has been considered as a preliminary step rather than as a stage that can be included in the calibration process. This research develops a methodology to calibrate the OD matrix jointly with model behavior parameters using a bi-level calibration framework. The upper level seeks to identify the best model parameters using a genetic algorithm (GA). In this level, a statistically based calibration objective function is introduced to account for disaggregate form of ITS data in the calibration of microscopic traffic simulation models and, thus, accurately replicate dynamics of observed traffic conditions. Specifically, the Kolmogorov-Smirnov test is used to measure the "consistency" between the observed and simulated travel time distributions. The calibration of the OD matrix is performed in the lower level, where observed and simulated travel times are incorporated into the OD estimator for the calibration of the OD matrix. The interdependent relationship between travel time information and the OD matrix is formulated using a Extended Kalman filter (EKF) algorithm, which is selected to quantify the nonlinear dependence of the simulation results (travel time) on the OD matrix. The two test sites are from an urban arterial and a freeway in Houston, Texas. The VISSIM model was used to evaluate the proposed methodologies. It was found that that the accuracy of the calibration can be improved by using disaggregated data and by considering both driver behavior parameters and demand.

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In today's database management systems (DBMS), concurrency control is one of the main issues that draw a lot of attention. Concurrency control protocols prevent changes to the database made by one user to interfere with those made by another user. During last couple of decades, many new concurrency control mechanisms were introduced into the study of database management systems. Researchers have designed new concurrency control algorithms and examined their performances in comparison with well known concurrency control mechanisms, which are widely used in today's database management systems. The results reported to date, rather than being definitive, have tended to be quite contradictory [1]. The main cause of such findings is use of different assumptions and implications when defining a simulation model for database management systems. Different coding schemes and logical programmatic flows play another important role in obtaining questionable results. In this paper, rather than proposing yet another concurrency control algorithm, I will implement a standardized simulation model within windows application that can then be used by any researcher to test performance of his concurrency control protocol. I will implement Optimistic Concurrency control protocol to validate functionality of my application and compare it with two phase locking protocol.

The introduction of democracy in country of post-Apartheid South Africa precipitated both economic and social changes. These changes have led to the liberalisation of the economy and the movement of the agricultural sector from being highly regulated to a market-based sector. Consequently, the country‟s economy has become exposed to global uncertainties. These changes brought about the need for role players to understand the dynamics of the agricultural sector in order to forecast possible future trends and assess their impact on agricultural production and consumption. Projecting economic and environmental uncertainties in agriculture is essential to make informed decisions and sustain agribusinesses.</li> In an attempt to combat the challenges and to understand the dynamics mentioned above, a system of equations with the ability to simulate the dynamic interaction between production and consumption at a regional level for South African potato producers, policy makers and wholesalers, is developed in this study. Existing methodology on partial equilibrium modelling is applied to develop a tool that can be used to analyse the potential impact of relative environmental shifts on the South African potato industry. Individual equations, which are | vi collapsed into a single system of equations, are estimated by means of Ordinary Least Square (OLS). The specific objectives of this study are as follows: <ul> <li> To estimate the potato area planted, yield and consumption of various categories of potatoes, in order to determine the price elasticity of demand and elasticity of supply.</li> <li> To develop a system of equations that will be used to generate baseline projections of demand and supply in the industry.</li> <li> To undertake impact analysis of various scenarios over the period 2011 to 2015. Although the model developed is mainly South African focusing on regional production and national consumption, the dissertation will recommend the possibility of future studies that use this study as a springboard for further research. These recommended studies include the linking of other models to improve and simulate relations between the potato sector and other sectors, thereby emulating the actual economy.</li> <li> One such requirement is to connect the vegetable and potato industries, a move which agricultural sector experts believe will benefit the outcomes of the potato industry.</li></ul> Consumption is estimated at national level, and is conducted according to the use of informal fresh and formal fresh potatoes for processing and seed potatoes. It is advisable for future research and study to estimate and project production and consumption at regional level. The baseline projection will be developed, and then the study will further undertake several scenarios which will lead to various possible future outcomes, discusses and document the response. Eventually, the model shows possible relationships, uncertainties and interactions between potato productions, consumption and prices. And that the domestic price, quantity demanded, the supply and the net exports actually determine the South African market equilibrium price and the decision to export in the South African potato industry. This is also called the near autarky situation. Copyright / Dissertation (MSc(Agric))--University of Pretoria, 2012. / Agricultural Economics, Extension and Rural Development / unrestricted

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The mature textile industry coupled with our familiarity and comfort level with fabrics and the possibility of seamless integration of electronic components such as sensors, processors, and power sources in the fabric opens up a new dimension of computing. The electronic textile presents a suitable substrate over which numerous applications can be developed. Location awareness is one such application that can reap the benefits of e-textiles such that it can be widely deployed at a reasonable cost for assisting visually impaired people or to provide navigational help during emergency situations. This thesis describes an autonomous, wearable location awareness system that will determine a user's location within a building given a map of that building. The thesis examines the issues, constraints, and challenges concerning the design of such a system. The two-part location awareness algorithm computes the location and orientation within a room as well as determines the user's movement between rooms. The efficacy of the proposed system is demonstrated with a wearable prototype. / Master of Science

During the takeoff for a trampoline skill the trampolinist should produce sufficient vertical velocity and angular momentum to permit the required skill to be completed in the aerial phase without excessive horizontal travel. The aim of this study was to investigate the optimum technique to produce forward somersault rotation. A seven-segment, subject-specific torque-driven computer simulation model of the takeoff in trampolining was developed in conjunction with a model of the reaction forces exerted on the trampolinist by the trampoline suspension system. The ankle, knee, hip, and shoulder joints were torque-driven, with the metatarsal-phalangeal and elbow joints angle-driven. Kinematic data of trampolining performances were obtained using a Vicon motion capture system. Segmental inertia parameters were calculated from anthropometric measurements. Viscoelastic parameters governing the trampoline were determined by matching an angle-driven model to the performance data. The torque-driven model was matched to the performance data by scaling joint torque parameters from the literature, and varying the activation parameters of the torque generators using a simulated annealing algorithm technique. The torque-driven model with the scaled isometric strength was evaluated by matching the performance data. The evaluation produced close agreement between the simulations and the performance, with an average difference of 4.4% across three forward rotating skills. The model was considered able to accurately represent the motion of a trampolinist in contact with a trampoline and was subsequently used to investigate optimal performance. Optimisations for maximum jump height for different somersaulting skills and maximum rotation potential produced increases in jump height of up to 14% and increases of rotation potential up to 15%. The optimised technique for rotation potential showed greater shoulder flexion during the recoil of the trampoline and for jump height showed greater plantar flexion and later and quicker knee extension before takeoff. Future applications of the model can include investigations into the sensitivity of the model to changes in initial conditions, and activation, strength, and trampoline parameters.