188,541 research outputs found
Allocation of Manpower
In this study, the heat recovery from exhaust gas at the ACE Power Embilipitiya (Pvt) Ltd (APE) in Sri Lanka was conceptually proposed and evaluated. APE has an installed capacity of 100 MW comprising 14 units of 7.5MW medium speed diesel engines fired with heavy fuel oil. There is only a minimum recovery of waste heat in the plant at the moment, only for fuel preheating, whereas waste heat recovery (WHR) boilers of 750kWth are equipped on eight engines. The larger portion of the waste heat is dumped into the environment without being used in any reasonable way. The objective of this work was to design a HRSG system for the remaining six engines to recover maximum possible heat from the exhaust gas and select a suitable steam turbine according to the heat demand capacity of the proposed HRSG, for generating additional power and thus converting the APE plant into a sort of a combined cycle. At the initial stage of the investigation, the amount of recoverable waste heat was estimated by evaluating the known parameters of the engines at fully loaded condition. The maximum theoretical waste heat recovery potential from the exhaust gas stream of one engine was calculated as 9807.87 MJ/h, equivalent to a heat rate of 2724.4 kW. The modelling and optimization of the proposed HRSG was done using the Engineering Equation Solver (EES) software, considering technical and practical limitations such as pinch point temperature difference, approach point temperature difference, terminal temperature difference and sulphur dew point in the stack. A commercially available steam turbine with a power output of 3.579 MW was selected as the optimum steam turbine for the desired conditions, utilising 12884.4 MJ/h of recovered waste energy amounting to 21.89% of the total available energy in the flue gas
Identification of relevant environmental descriptors
Based on previous experiences and a literature review the most relevant environmental descriptors were selected and tested by means of field experiments. These included: (i) the temperature-humidity index (THI), (ii) the cattle stocking system (rotational stocking, continuous stocking or strip-grazing), (iii) the botanical composition of the grasslands, (iv) the net grassland productivity in terms of Net Energy (NE) and/or energy-corrected milk (ECM) per unit grassland area, and (v) the behaviour of dairy cows within grazing herds as recorded with SensOor® technology
The Roles of Labor and Profitability in Choosing a Grazing Strategy for Beef Production in the U.S. Gulf Coast Region
Comparisons are made concerning labor required and profitability associated with continuous grazing at three stocking rates and rotational grazing at a high stocking rate in the U.S. Gulf Coast region. A unique data set was collected using a time and motion study method to determine labor requirements. Profits are lowest for low stocking rate– continuous grazing and high stocking rate–rotational grazing. Total labor and labor in three specific categories are greater on per acre and/or per cow bases with rotational-grazing than with continuous-grazing strategies. These results help to explain relatively low adoption rates of rotational grazing in the region.labor requirements, rotational grazing, stocking rate, time and motion study, Agribusiness, Food Consumption/Nutrition/Food Safety, Industrial Organization, Labor and Human Capital, Livestock Production/Industries, Q12, Q24,
State Fish Stocking Programs at Risk: Takings Under the Endangered Species Act
Part I of this article provides a brief background to fish stocking practices in the United States, including a discussion of beneficial fish stocking practices, as well as some of the allegations surrounding the detrimental effects. Part II of this article provides some necessary background on section 9 of the ESA, the “actual injury” prong, the “significant impairment” prong, and their application to fish stocking. Part III of this article sets forth recommendations for future clarification and increased consistency on these issues. Specifically, this article supports the use of two rules that can help reconcile the uncertain landscape surrounding a taking based on habitat modification. First, “actual injury” should be found where there is injury to either an individual or a population of protected species. Second, the degree of proof required to establish an “injury” where essential behaviors are impaired should be bifurcated into two tests, depending on which behavioral pattern is being adversely affected. Together, these rules can bring resolution not only to scenarios like fish stocking, but also to other future fact patterns scrutinized under the habitat modification analysis. Part IV of this article demonstrates how application of these rules to states can further the goals of the ESA, both through voluntary reevaluation of fish stocking programs, and through application for an Incidental Take Permit and corresponding Habitat Conservation Plan. These rules can provide two different paths to the same goal: to minimize adverse impacts to endangered and threatened species
The potential cost to New Zealand dairy farmers from the introduction of nitrate-based stocking rate restrictions
Introducing a stocking rate restriction is one possible course of action for regulators to improve water quality where it is affected by nitrate pollution. To determine the impact of a stocking rate restriction on a range of New Zealand dairy farms, a whole-farm model was optimised with and without a maximum stocking rate of 2.5 cows per hectare. Three farm systems, which differ by their level of feed-related capital, were examined for the changes to the optimal stocking rate and optimal level of animal milk production genetics when utility was maximised. The whole-farm model was optimised through the use of an evolutionary algorithm called differential evolution. The introduction of a stocking rate restriction would have a very large impact on the optimally organised high feed-related capital farm systems, reducing their certainty equivalent by almost half. However, there was no impact on the certainty equivalent of low feed-related capital systems.environmental regulation, dairy farms, whole-farm model, evolutionary algorithm
Unintended Consequences of Price Controls: An Application to Allowance Markets
Price controls established in an emissions allowance market to constrain allowance prices between a ceiling and a floor offer a mechanism to reduce cost uncertainty in a cap-and-trade program; however, they could provide opportunities for strategic actions by firms that would result in lower government revenue and greater emissions than in the absence of controls. In particular, when the ceiling price is supported by introducing new allowances into the market, firms could choose to buy allowances at the ceiling price, regardless of the prevailing market price, in order to lower the equilibrium price of all allowances. Those purchases could either be transacted by a group of firms intending to manipulate the market or be induced through the introduction of inaccurate information about the cost of emissions abatement that causes firms to purchase allowances at the ceiling. Theory and simulations using estimates of the elasticity of allowance demand for U.S. firms suggest that the manipulation could be profitable under the stylized setting and assumptions evaluated in the paper, although in practice many other conditions will determine its use.cap-and-trade; climate change; price controls; price ceiling; manipulation; allowance market; carbon market
Modelling the impact of policies to reduce environmental impacts in the New Zealand dairy sector
Agriculture remains a major sector of the New Zealand economy, with the vast majority of farm and food production exported. The accelerating intensification of farming in New Zealand over recent decades raises concern over the current sustainability of New Zealand farming, and whether it can remain so in the future. In this study, we focus on the impacts of policies to reduce environmental impacts of dairy farming, with a particular focus on nitrogen pollution and greenhouse gases (GHG) emissions. We use a modified version of the Global Trade Analysis Project (GTAP) model and database, with improved specification of the agricultural sector and land-use. We augment the model with environmental indicators for New Zealand, including nitrogen balances and GHG emissions.
We simulate a range of scenarios involving reductions in fertiliser use and stocking rates on dairy farms, from an updated 2010 database. In particular, we consider seven scenarios, with the objective of exploring reductions in the dairy stocking rate and the application of nitrogenous fertiliser to dairy farms to target reductions in the dairy sector’s nitrogen balance of 10%, 20% and 30%. Reducing fertiliser use and stocking rates are two of the approaches that dairy farmers can take in order to reduce their emissions of nitrogen and GHGs. Our results suggest that the nitrogen balance could be reduced by 10% with a 16% cut in nitrogenous fertiliser and a 5% fall in the stocking rate. Reducing fertiliser use and stocking rate by 31% and 11% respectively could result in a 20% cut to the dairy sector’s nitrogen balance. To achieve a 30% reduction in the nitrogen balance, our results suggest that the cut back in fertiliser use would need to be 45%, with the stocking rate reduced by 19%. Across these scenarios, our results indicate that value added in the dairy farm sector could fall by between 2% and 13%, while export earnings from dairy products may fall by between US1,145 million
Stocking, Enhancement, and Mariculture of Penaeus orientalis and Other Species in Shanghai and Zhejiang Provinces, China
China's marine aquaculture landings provide only 18% of its combined freshwater and amrine capture and culture landings, at a per-capita consumption of only 3.2 kg/yr out of a total of 18.1 kg/yr. We described development and some of the results of long-term mariculture and stocking/enhancement projects that have been underway for up to 20 years in the Hangzhou Bay area. Penaeus orientalis (also referred to as P. chinensis) stocking provided up to 400 t/yr, at a total cost-benefit ratio of up to 8 Yuan of landed shrimp per Yuan invested in shrimp stocking. Over 40 t of Penaeus orientalis were produced commercially in 1993, with proceeds being used to fund mariculture and fisheries research. Large scale edible jellyfish restocking is also underway, while semicommercial culture of abalone, Haliotis diversicolor, has been successful. Technical problems limitig mariculture have been solved successfully for some species
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