6 resultados para Span

em Greenwich Academic Literature Archive - UK


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Over a time span of almost a decade, the FUELCON project in nuclear engineering has led to a fully functional expert system and spawned sequel projects. Its task is in-core fuel management, also called `refueling', i.e., good fuel-allocation for reloading the core of a given nuclear reactor, for a given operation cycle. The task is crucial for keeping down operation costs at nuclear power plants. Fuel comes in different types and is positioned in a grid representing the core of a reactor. The tool is useful for practitioners but also helps the expert in the domain to test his or her rules of thumb and to discover new ones.

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The paper considers the open shop scheduling problem to minimize the make-span, provided that one of the machines has to process the jobs according to a given sequence. We show that in the preemptive case the problem is polynomially solvable for an arbitrary number of machines. If preemption is not allowed, the problem is NP-hard in the strong sense if the number of machines is variable, and is NP-hard in the ordinary sense in the case of two machines. For the latter case we give a heuristic algorithm that runs in linear time and produces a schedule with the makespan that is at most 5/4 times the optimal value. We also show that the two-machine problem in the nonpreemptive case is solvable in pseudopolynomial time by a dynamic programming algorithm, and that the algorithm can be converted into a fully polynomial approximation scheme. © 1998 John Wiley & Sons, Inc. Naval Research Logistics 45: 705–731, 1998

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The recent history and current trends in the collection and archiving of forest information and models is reviewed. The question is posed as to whether the community of forest modellers ought to take some action in setting up a Forest Model Archive (FMA) as a means of conserving and sharing the heritage of forest models that have been developed over several decades. The paper discusses the various alternatives of what an FMA could be, and should be. It then goes on to formulate a conceptual model as the basis for the construction of a FMA. Finally the question of software architecture is considered. Again there are a number of possible solutions. We discuss the alternatives, some in considerable detail, but leave the final decisions on these issues to the forest modelling community. This paper has spawned the “Greenwich Initiative” on the FMA. An internet discussion group on the topic will be started and launched by the “Trafalar Group”, which will span both IUFRO 4.1 and 4.11, and further discussion is planned to take place at the Forest Modelling Conference in Portugal, June 2002.

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In this study, a simplified Acoustic Emission (AE) equipment, in essence an AE signal conditioner and a USB (Universal Serial Bus) data acquisition system, is used to study what happens in paper structures during mechanical loading. By the use of such equipment, some parameters that can be extracted are e.g. the stress and strain at onset of AE, the stress and strain at the onset of rapid AE defined as some numerical factor (larger then one) times the initial emission rate, the emission rate at the first stage of loading and the stress and strain at final failure i.e. when the specimen loses its load carrying ability.In this study however, the interest is focused on one particular parameter i.e. the elastic strain energy density W c at onset of AE. This is a parameter with a clear physical meaning and in this study, the correlation between this parameter and a fracture toughness measure, is investigated.The conclusion is that when nine different paper materials (with a large span regarding properties) are considered, there is a correlation (however not linear) between these two parameters.

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The physical and financial demands of caring for a child with complex needs are acknowledged by health professionals. However, the emotional needs of parents are not often recognized by health professionals until parents are at a heightened level of stress. This paper is based on a literature review of current articles, research papers and government documentation. The focus is on the emotional impact to parents who have a child with complex needs, particularly at the point of diagnosis. The paper explores how health professionals, and nurses in particular, should meet the emotional needs of parents in order to support them more effectively. Giving birth to a child with severe health problems impacts upon parents at an emotional time of transition, particularly if there were no concerns identified during pregnancy. For some parents a grief response or state of chronic sorrow may be triggered. The reality of caring for a baby who is critically ill or disabled can be an enormous and unexpected shock for both parents. Parents need emotional support and guidance, as they may have to change their expectations for their child’s development and even life span. It is important for nurses to realise that if parents’ emotional needs are unmet it can lead to clinical depression or mental illness. Primary support often comes from parent support groups rather than health professionals. The review highlights factors affecting parents’ emotions and discusses how early support, home visits and practical help can all help to alleviate parents’ emotional stress.

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The physical and financial demands of caring for a child with complex needs are acknowledged by health professionals. However the emotional needs of parents are not often recognised by health professionals until parents are at a heightened level of stress. This paper is based on a literature review of current articles, research papers and government documentation. The focus is on how health professionals, and nurses in particular should meet the emotional needs of parents who have child with complex needs, particularly at the point of diagnosis. Giving birth to a child with severe health problems impacts upon parents at an emotional time of transition, particularly if there were no concerns identified during pregnancy. For some parents a grief response or state of chronic sorrow may be triggered. The reality of caring for a baby who is critically ill or disabled can be an enormous and unexpected shock for both parents. Parents need emotional support and guidance, as they may have to change their expectations for their child’s development and even life span. Primary support often comes from parent support groups rather than health professionals. The review discusses how home visits, practical help and early support can all help to alleviate stress. It is important for nurses to realise that if parents’ emotional needs are unmet they can lead to clinical depression or mental illness. This literature review looks at the emotional impact on parents and explores how nurses can address this issue in order to support parents more effectively. It identifies key areas that nurses could address that would help alleviate parents’ emotional stress.