Seeds are very complex and diverse plant organs. Seed germination is the most sensitive stage of plant life and is influenced by various environmental signals including phytohormones, salt, light, temperature and water potential. Seeds have an innate mechanism called dormancy that blocks germination, and plants have developed several dormancy-inducing strategies to optimise the timing of germination. Seed germination vigour is an important factor in crop yield. Seedling vigour is defined as the sum of the seed properties which determine the level of activity and performance during germination and seedling emergence. A poor seed lot can be improved by post-harvest treatment such as hydro-priming as it is used in the seed industry, but the biological mechanism is unknown. The aim of this study is to understand the mechanism(s) of hydro-priming in order to improve seed vigour and seed germination. I set seeds at different temperatures to produce variation in seed vigour and it showed that germination of seeds with low vigour can be improved by hydro-priming. Using LC-IT-ToF/MS I characterised compounds that leach from seeds during hydro-priming, and showed that some of these are putative germination inhibitors. Adding these compounds to the water during hydro-priming showed that the inhibitory effect of these compounds is not the main mechanism that regulates germination. Also, transcriptomic analysis showed that genes involved in OPDA pathway are expressed during hydro-priming as well as during endosperm weakening cap associated genes. I concluded that hydro-priming improves the speed of germination of low temperature set and its efficiency is dependent of activation of metabolic activity.

<p> In the summer of 1976 a study was undertaken of the Woodville/Codroy gypsum karst plain, an area of about 4 km^2 in southwest Newfoundland. Geology of the gypsum is revised and the general geomorphology described. Sinkholes were surveyed and classifications based on several criteria are presented. Hydro-chemistry is reported in some detail from field and laboratory analyses. It is shown that the gypsum karst system evolves in much the same \'Jay as that of limestone but at a greater rate, permitting comprehensive study of morphologic evolution within post-glacial karst areas. Processes at work in the gypsum may be initially simpler than those in carbonates but complexities of rock characteristics complicate the picture. Some water measurements indicate diffuse flow conditions in the aquifer, while others suggest conduit flow; it is demonstrated that both diffuse and conduit flow systems may operate in conjunction. </p> / Thesis / Master of Arts (MA)

No description available.

The thesis presents models for short term planning (24 hours) of a hyro dominated hydrothermal power system. The purpose of the models is to minimizae the system operation costs to provide a forecasted load and keep enough spinning reserve. / This thesis presents models for short term planning (24 hours) of a hydro dominated hydrothermal power system. The purpose of the models is to minimize the system operation cost to provide a forecasted load and keep enough spinning reserve.   The thesis focuses on two issues in hydro power modelling. The first issue is the relationship between water discharged and power generated. This relationship is a non-linear and non-convex function. If the plant has several units, the efficiency of the plant will have local maximums, so called local best-efficiency points. The second issue is to take into account the cost of start-ups of hydro units in the planning.   The hydro model is mixed-integer. Discharg􀁐s are allowed at zero flow, the local best-efficiency points and on the continuous part between the local best-efficiency point with the highest flow and the point with maximum flow. This last continuous part is modelled as a linear function. In order to get data for the start-up cost a survey among the largest power producers in Sweden has been made, where three questions about start-ups of hydro power units has been asked: What causes the costs in the start-up?, How much does a start-up cost? and How do start-ups effect the short-term scheduling strategies of power producers in Sweden? The results show that a fair estimate of the start-up cost is about $3/MW nominal output. For the thermal plants a standard model with polynomial operation cost, start-up costs and ramp-rate constraints has been used. The model also includes the possibilities of purchasing and selling power to forecasted prices.   The planning problem is formulated as a mathematical programming problem. The solution technique uses Lagrange relaxation to decompose the problem into subproblems. There will be one subproblem for each hydro and thermal plant. In order to find good feasible solutions a heuristic technique to change the integer variables in the hydro system has been developed. The Lagrange multipliers are updated with the subgradient method.   The models are tested in three different load situations; a winter day (heavy load), an autumn day (medium load) and a summer day (light load). The result shows that the method gives near optimal schedules in reasonable computation time in cases with a normal part of the thermal units committed. The assumed start-up cost results in that hydro units almost never are started or stopped for one hour only. / <p>QC 20161206</p>

The thesis contains the results of a reseach project on application of mathematical programming methods to short-term operation planning of large hydrothermal power systems. The project was aimed at devoeloping efficient solution techniques that are practially applicable to large systems. The problem is modeled as a large mixed integer program. / This thesis contains the results of a research project on application of mathematical programming methods to short-term operation planning of large hydrothermal power systems. The work was carried out at the Department of Electric Power System Engineering of the Royal Institute of Technology, Stockholm, Sweden.   The project was aimed at developing efficient solution techniques that are practically applicable to large scale power systems. The thesis consists of seven chap­ters and four appendices.   The increasing importance and the magnitude of the expenditures associated with it have created an urgent necessity to operate the electric energy systems in an optimal economic manner. The optimal operation planning, as explained in chapter 1, can be divided into several subproblems which are more computationally manageable. The short-term operation planning contains two of these subproblems, namely; weekly and daily operation planning.   The problem, as modeled in chapter 2 for systems with a considerable amount of hydro, is a large mixed integer program. The objective for this problem is the produc­tion cost of the thermal plants. The optimization hori­zon varies from one week to one day, and the discretiza­tion intervals are normally chosen between one to several hours.   In chapter 3, Lagrangian relaxation technique and Benders' method are introduced to decompose the problem with re­spect to hydro and thermal systems. This makes it poss­ible to exploit the special characteristics of each system.   The hydro problem is a large linear program with embedded network structure. In chapter 4, several solution techniques are introduced that exploit this special structure of the large number of constraints involved. The small nonlinearities of hydro problem and· head variation are also treated in this chapter.   The thermal problem involves integer variables. In cha­ter 5, the special structure of this problem is consider­ed, which results in a considerable amount of reductions. Branch and bound, shortest path, and discrete dynamic programming methods are considered for solution of thermal system. This chapter is extended to consider hydro­thermal power system with low amounts of hydro.   Chapter 6 concerns network labeling system, network flow algorithms, and sparsity techniques, which were considered in the implementation of the algorithms.   Finally, the test results and conclusions from application of different techniques are considered and discussed in chapter 7. The Swedish System has been used to prove the applicability and efficiency of the developed techniques. The short-term model can be used in operation, as an engineering tool for decision making, and in planning, to analyze alternative planning schemes. / <p>QC 20161206</p>

No description available.

About 74 million of the world population needs assistive leg devices on daily basis on account of some form of disability. Although the standard wheelchairs perform well on level ground terrains but they prove ineffective on soft ground and in crossing large obstacles. For dealing with the advance challenges of navigating the human environment a biped walker seems to a more suitable choice. The research presented here is focused on building and actuating a two-joint leg structure that is an integral part of ongoing leg-chair project in Popovic Labs. The project provides a proof of concept that how the synthetic hydro muscles (also developed by Popovic Labs) can be used for the control of large artificial limb joints. Here we discuss the designing, testing and corresponding refining of electronics design, actuation and control of the bi-joint hydro muscle actuated leg structure .We will also elaborate on the requirements, design, problems and refinement of some of the important mechanical components like Coupler/Decoupler and Force Multipliers.

Approximately 60% of New Zealand's electricity is produced from hydro generation. The Waitaki River catchment is located in the centre of the South Island of New Zealand, and produces 35-40% of New Zealand's electricity. Low inflow years in 1992 and 2001 resulted in the threat of power blackouts, and a national demand for electricity that is currently growing at 2 to 5% a year gives strong justification for better management of the hydro resource. Improved seasonal rainfall and inflow forecasts will result in the better management of the water used in hydro generation on a seasonal basis. Seasonal rainfall forecasting has been the focus of much international research in recent years, but seasonal inflow forecasting is in its relative infancy. Researchers have stated that key directions for both fields are to decrease the spatial scale of forecast products, and to tailor forecast products to end user needs, so as to provide more relevant and targeted forecasts, which will hopefully decrease the enormous socio-economic costs of climate fluctuations. This study calibrated several season ahead lake inflow and rainfall forecast models for the Waitaki river catchment, using statistical techniques to quantify relationships between land-ocean-atmosphere state variables and seasonally lagged inflows and rainfall. Techniques included principal components analysis and multiple linear regression, with cross-validation techniques applied to estimate model error. Many of both the continuous and discrete format models calibrated in this study predict anomalously wet and dry seasons better than random chance, and better than the long term mean as a predictor. 95% confidence limits around most model predictions in this study offer significant skill when compared with the range of all probable inflows (based on the 80 year recording history in the catchment). Models predicting winter Lake Pukaki inflows are those with the strongest predictive relationships in this study. Spring and summer predictions were generally less skilful than those for winter and autumn. Inflows could be predicted with some skill in winter and summer, but not rainfall, and rainfall could be predicted with some skill in autumn and spring, but not inflows. Models predicting inflows and rainfall for different seasons in this study use very different sets of predictor variables to accomplish their seasonal predictability. This may be related to the significant seasonal snow storage in the catchment, so that other factors such as temperature and the number of north-westerly storms may have a large part to play in the magnitude of inflows. Similarly, predicting the same dependent variable but for different seasons led to different contributing variables, leading to the conclusion that different wider physical causative mechanisms are behind the predictability in different seasons, and that they too should be studied separately in any future research. SST5 (sea surface temperature to the north of New Zealand) was found to have more relevance than any other predictor in predicting Waitaki river inflows and rainfall in any season. The models calibrated with SOI and IPO included as predictor variables were almost invariably worse in their predictive skill than those without, and the list of the most important predictor variables in all models did not include equatorial sea surface temperatures, sea level pressures, or 700hpa geopotential height variables. The conclusion from these findings is that equatorial ocean-atmosphere state variables do not have significant relationships with season ahead inflows and rainfall in the South Island of New Zealand. Seasonal climate forecasting on single catchment scale, and focussed to end user needs, is possible with some skill, at least in the South Island of New Zealand.

Magnesium alloy tubes have good formability at elevated temperatures. In this paper, firstly, uniaxial tensile tests are conducted to evaluate the flow stress of AZ61 magnesium alloy at different temperatures and strain rates. Secondly, a hydraulic warm forming machine with axial feeding, counter punch and internal pressure is designed and manufactured. Using this testing machine with the FEM results, experiments of hydraulic forming of AZ61 magnesium alloy tubes at different temperatures are carried out. The effect of loading paths on the product shape and formability at different temperature are discussed.

ABSTRACT The objective of this study is to obtain the friction coefficient of lubricants in tube hydroforming of guiding zone. Lubricants, universal testing machine, and friction test machine in tube hydroforming of guiding zone are used to carry out the experiments of aluminum alloy tubes. Lubricants are categorized according to their performance as follows: (1) oils, (2) emulsions, and (3) slide lacquer. Different lubricants tests, it is known that the best lubrication is derived from slide lacquer, while oils showed the poorest behavior. Different internal pressure tests, it is known that greater internal pressure causes the coefficient of friction decreasing. Different sliding velocity, it is known that sliding velocity does not affect the coefficient of friction at 100mm/min. And using CCD which is an optical instrument obtains the surface of tubes after experiments.