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801.
802.
针对某船用增压锅炉过热器结构复杂的特点,用PRO/E建立了过热器内蒸汽空间的整体三维模型,选择更合理的边界条件,以流体力学基本方程组和标准的k—ε双方程湍流模型为数学模型,对不同结构参数的过热器蒸汽流场分别进行了整体三维数值模拟,直接得到并联各管蒸汽质量流量分配规律。分析、归纳并验证了影响流量偏差的各种结构因素。计算结果表明,该型过热器采用细密管束沿集箱轴向均匀进汽,并将第二、三流程沿炉膛宽度方向分隔成三部分的特殊结构,能显著减小各部分的流量偏差与热负荷偏差,并利用倾斜挡板减缓了集箱腔体内沿流向的静压下降幅度,使流量偏差与炉膛热负荷分布保持一致。挡板形状和流程布置方式有利于减小过热器管束的壁温差异。当保持过热器的其它结构特征(流程布置方式、挡板型式、管束引入引出方式和位置等)不变时,流量分配不均匀性取决于单位集箱长度上的支管总横截面积与集箱横截面积之比,以及支管平均长度与集箱长度之比两个参数,前者越小,或后者越大,则支管流量分配越均匀。计算方法和结果对于过热器结构优化设计有重要参考价值,并为建立流量偏差同结构参数之间的通用性关联式奠定了基础。 相似文献
803.
AbstractAn increasing threat to the marine environment is the presence of debris in the ocean, which is predominantly a result of land-based sources and increasing use of single-use packaging items. To begin reducing the amount of debris entering the ocean, human behavior must be addressed. The purpose of this study is to evaluate how coastal recreationists behave towards the environment and whether their participation in recreation correlates to their reported behavior specific to marine debris control. Path analysis was used to determine how one’s attitudes, knowledge, recreational activity, and background characteristics influence behavior. Results showed that type of recreational activity had very little impact on behavior and other predictors. From the model, marine environmental concern, connection to the marine environment, and gender most directly influenced reported behavior. Therefore, to encourage change in recreationists’ relevant behavior, the results indicate social groups where behavior change efforts could initially be made. Additionally, the marine environmental concerns of different demographic groups should be considered and used in developing programs directed at increasing environmentally responsible behavior with emphasis on marine debris. 相似文献
804.
李福海 《青岛远洋船员学院学报》2013,(3):57-59
《船舶管理》课程是轮机工程技术专业的核心课程之一,在专业人才培养中具有非常重要的地位和作用.在新的教育背景下,应充分利用各种资源,进行教学改革,以达到现代航海教育的要求,培养优秀的航运人才. 相似文献
805.
在轮机工程技术专业教学实践总结的基础上,探讨实施基于虚拟机舱桌面系统的小班化教学,为在高职院校轮机专业课程教学改革中广泛推广应用轮机桌面系统提供借鉴和参考。 相似文献
806.
全面地论述了各船级社最新的环保船级符号和附加符号对中央空调和冷藏设备的制冷剂的要求,为后续新船设计作参考。 相似文献
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This article analyzes institutional arrangements for the delivery of coastal programs through a new way of thinking about their evolution and structure. The notion of three distinct "dimensions" describing the phases in the evolution of institutional arrangements is introduced. The notion of dimensions is developed from conceptualizing about how institutional arrangements are diagrammed. This allows the visualization of how individual institutions and key stakeholders relate to each other in the delivery of coastal programs, how effective these relationships are, and how their relationships could be redesigned. "Dimensional thinking" enables the re-examination of existing institutional design of coastal programs and how these can evolve to meet the challenges of the new millennium. It is concluded that institutional arrangements have grown from a single dimensional view, where institutions (mainly governmental) delivered programs in isolation, through to the present second dimension where agency programs are managed through coordinating bodies and through coastal management plans. It is argued that a third dimension of institutional arrangements, one that recognizes and embraces the rapid pace of change in this century, will be needed that is aligned by themes rather than by organizational structure. To illustrate a third dimension a visualization tool is developed drawing from management cybernetics. It recognizes the increasing importance of formal and informal networks in relation to traditional modernist hierarchical management by recognizing multiple stakeholders (government at all levels, industry, advocacy groups, conservation interests, and the broader community) and their degree of mutual dependence. Dimensional thinking has the potential to institutionalize the interaction between these multiple stakeholders to ensure the effective delivery of coastal programs in the new millennium. A single answer to what the third dimension of coastal management program evolution should include is not presented. Rather, an approach is presented that allows coastal managers to move forward in the debate on redesigning coastal programs to meet today's complex suite of issues, values, and interests. An experimental case study from Western Australia is used to illustrate the potential application of the dimensional thinking to coastal management institutional design in that State's coastal program. 相似文献
810.