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1.
Mathematical modeling of river ice processes   总被引:6,自引:0,他引:6  
River ice processes involve complex interactions between hydrodynamic, mechanical, and thermal processes. River ice research has largely been driven by engineering and environmental problems that concern society, including ice effects on flooding, hydropower, navigation, ecology, and the environment. Important findings on river ice research before 1980 have been summarized by Ashton (1986) and Donchenko (1987). Significant progress has been made in river ice research in the last three decades. Mathematical modeling has been an essential part of this progress. Mathematical models have been developed for various river ice processes. They not only helped to advance understanding of the physical processes by complementing field and laboratory studies, but also provided tools for planning and design of engineering projects. In this paper, models of various river ice processes during the winter, from freeze-up to breakup, are reviewed after a brief overview of river ice phenomena. Following the discussion of these ‘component’ models, a discussion on ‘comprehensive’ models and an analytical framework which links all river ice processes in a coherent manner is presented.  相似文献   

2.
Professional practice is considered as a much broader topic for inclusion in engineering curricula than traditionally associated with engineering design. Practicing engineers require a working knowledge of several non-engineering disciplines and must interact with people of a variety of backgrounds within a variety of organizational contexts. Engineers must develop the skills of problem solving and decision making for circumstances much broader than generally used in the engineering class room. Professional engineering practice in this broad context can be the subject of legitimate research and instruction. Case research methods are applicable to the exploratory study of engineering practice and the development of a knowledge base important to designing engineering curricula. Case instruction provides one method of dealing with topics at the boundaries of the engineering disciplines and in developing decision making skills that are fundamental to engineering practice. It is concluded that the engineering education community should explore new frameworks for research, instruction and the associated scholarship that address professional practice issues.  相似文献   

3.
Since the use of standard engineering methods in the process of an ice bank performance evaluation offers neither adequate flexibility nor accuracy, the aim of this research was to provide a powerful tool for an industrial design of an ice storage system allowing to account for the various design parameters and system arrangements over a wide range of time varying operating conditions. In this paper the development of a computer application for the prediction of an ice bank system operation is presented. Static, indirect, cool thermal storage systems with external ice on coil building/melting were considered. The mathematical model was developed by means of energy and mass balance relations for each component of the system and is basically divided into two parts, the model of an ice storage system and the model of a refrigeration unit. Heat transfer processes in an ice silo were modelled by use of empirical correlations while the performance of refrigeration unit components were based on manufacturers data. Programming and application design were made in Fortran 95 language standard. Input of data is enabled through drop down menus and dialog boxes, while the results are presented via figures, diagrams and data (ASCII) files. In addition, to demonstrate the necessity for development of simulation program a case study was performed. Simulation results clearly indicate that no simple engineering methods or rule of thumb principles could be utilised in order to validate performance of an ice bank system properly.  相似文献   

4.
The concept of prototypical accident scenario has been used since the late 1980s in French road safety research. A prototypical scenario can be defined as a prototype of the accident process corresponding to a series of accidents which are similar in terms of the chain of facts and causal relationships found throughout the various accident stages. This concept provides a means of combining and generalising the knowledge obtained from accident case studies, based on in-depth investigation methods or on detailed analyses of police reports. Applications of this concept are developed in both the field of traffic accident research and safety studies (diagnoses) in preparation for engineering measures or local safety policies. This paper presents the prototypical scenario concept, its theoretical background, and the way it is used for safety research and studies.  相似文献   

5.
Offshore operators in the Arctic will rely on seafloor installations, notably pipelines, to manage and transport hydrocarbons. In icy waters, these structures are at risk of being damaged by gouging ice features, either icebergs or sea ice ridges. This phenomenon generally occurs when an ice feature drifts into shallower areas and its keel starts plowing the seabed over considerable distances. It is generally agreed that adequate protection against these events can be achieved by burying the pipeline below the seafloor. The question is: what constitutes a safe and economical burial depth for any given location? An answer to this question requires adequate knowledge of material properties (soil, ice keel and pipeline), a reliable handle on the processes taking place during gouging and a consensus on what constitutes acceptable risks. Research on this subject has been on-going for the past few decades, along several fronts. One is by means of field studies, including replicating gouging scenarios in a natural environment, in situ ice characterization, seabed mapping and on-land relict gouge investigations. Another is through laboratory studies, either at single gravity or in a centrifuge. Theoretical analyses and numerical simulations have also contributed to our current understanding of gouging phenomena. Several research groups proposed some form of guidelines for estimating gouging parameters—examples are presented. These methodologies are instructive in that they represent an integrated approach to an improved understanding of gouging phenomena. They point the way to what one may expect in terms of future guidelines to a safe and cost-effective burial depth.  相似文献   

6.
Micro-organisms play a vital role in many biological, medical and engineering phenomena. Some recent research efforts have demonstrated the importance of biomechanics in understanding certain aspects of micro-organism behaviours such as locomotion and collective motions of cells. In particular, spatio-temporal coherent structures found in a bacterial suspension have been the focus of many research studies over the last few years. Recent studies have shown that macroscopic properties of a suspension, such as rheology and diffusion, are strongly affected by meso-scale flow structures generated by swimming microbes. Since the meso-scale flow structures are strongly affected by the interactions between microbes, a bottom-up strategy, i.e. from a cellular level to a continuum suspension level, represents the natural approach to the study of a suspension of swimming microbes. In this paper, we first provide a summary of existing biomechanical research on interactions between a pair of swimming micro-organisms, as a two-body interaction is the simplest many-body interaction. We show that interactions between two nearby swimming micro-organisms are described well by existing mathematical models. Then, collective motions formed by a group of swimming micro-organisms are discussed. We show that some collective motions of micro-organisms, such as coherent structures of bacterial suspensions, are satisfactorily explained by fluid dynamics. Lastly, we discuss how macroscopic suspension properties are changed by the microscopic characteristics of the cell suspension. The fundamental knowledge we present will be useful in obtaining a better understanding of the behaviour of micro-organisms.  相似文献   

7.
What could we know about engineering student knowing? The answer to this question represents a form of scholarship of discovery in engineering education and a valuable complement to scholarship of teaching work in the field. To illustrate the state of this scholarship, we present twelve studies and analyze these studies across aspects of knowledge, level of experience, and research approach. We then use these analyses to identify trends in the existing research and opportunities for future research.  相似文献   

8.
本文提出了超声破块的新方法,对冰块样品的实验表明,利用5W/cm^2声强的超声可以达到300mm/min的破穿速度,作者介绍了这种实验方法,并认为:喷射声空化场的空化集中效应是超声破穿冰块的作用机制,最后,预测了这种超声破穿方法在冰处理工程上的应用。  相似文献   

9.
Ice adhesion to a cooling solid surface occurs in many situations, and it causes many serious problems that can lead to economic losses. Therefore, it is necessary to clarify the mechanism of ice adhesion to a cooling surface. In past studies, the adhesion force of ice was reported to be strongly governed by the surface energy of the cooling solid surface. In consideration of this surface energy, it is essential to investigate the ice adhesion force on a nano/micro scale. However, very little research has been conducted in nano/micro scale. Thus, in this paper, by using a scanning probe microscope (SPM), the methods for measuring the ice adhesion force and contact area between the cooling solid surface and formed ice are proposed, and the optimal measurement conditions of the SPM are determined. Then, the validity and effectiveness of the method are clarified.  相似文献   

10.
The recent trend of rapid growth in the scientific and engineering activities in East Asian Newly Industrializing Economies (NIEs) resulted in a change in the structure of world knowledge production. In South Korea, particularly, not only the numbers of publications have increased, but there is a noticeable change in the composition of scientific and engineering activities. This paper notes the most of the research on the knowledge production of advanced countries, along with a handful of studies about the knowledge production of latecomers. Recent changes in the patterns of knowledge production in latecomer countries provoke the deeper understanding about the underlying mechanisms of ongoing change. Therefore, this paper explores the patterns of knowledge production activities in latecomers by analyzing scientific and engineering capabilities using empirical evidence from Korea. The results suggest that the patterns of accumulation of knowledge production in Korea gradually evolved from engineering to scientific activities. Important policy implications can be drawn from the findings for supporting scientific and engineering research activity in the latecomers in general and NIEs in particular.  相似文献   

11.
This paper proposes a conceptual design tool, based upon inferential design theory. It has been specifically developed for the design of production and operations systems, but its use can be extended to other engineering areas, such as mechanical and structural systems. Inferential design theory and its foundation in the inferential theory of learning are briefly outlined. Both theories are based on the idea of using specialised knowledge operators in learning and design, termed knowledge transmutations and design knowledge transmutations respectively. The 24 transmutations existing in the two theories are outlined, and a further 12 design-specific transmutations are proposed. These have been developed as a result of our research. A conceptual design process is proposed, in which design knowledge transmutations are used. A software tool for design, CREDO, is also described and an example of its use in the generation of design concepts for an after-sales service facility is presented. The conclusions discuss the initial methodological experience of using CREDO to generate design concepts. They are based on the introductory use of CREDO at Technion in Israel for teaching purposes. Directions for further research are also provided.  相似文献   

12.
A semi-empirical method for calculating local ice forces on moored ships was described in Part 1 and is implemented for a real hull in this article. The method splits the ice actions into actions in the vicinity of the waterline caused by breaking of intact ice and rotation of broken ice floes, and actions below the waterline caused by ice-hull friction. The hull was discretized into flat panels and ice forces were calculated for each panel and summed to obtain the total ice action. The resolution of the discretization was studied and stable results were obtained with relatively few panels.The model was compared with model test data and satisfactory agreement was found for the mean mooring forces. Surge oscillations were larger in the simulations than in the model tests, probably due to underestimated ice-induced damping forces in the simulations.The dynamic surge response of the ship was investigated by varying the ice drift speed and the surge natural period. The coefficient of variation for the surge motions was largest for speeds around 0.10-0.15 m/s for all surge natural periods. The importance of parameterizing the ice forces in terms of the penetration of the ship into the ice is highlighted, as this strongly affects the dynamic response of moored ships in level ice.The model can be applied in studies of dynamic response of moored ships in level ice with constant drift direction and it can be extended to variable ice drift direction.  相似文献   

13.
The function of the engineering profession is to manipulate materials, energy, and information, thereby creating benefit for humankind. To do this successfully, engineers must have a knowledge of nature that goes beyond mere theory—knowledge that is traditionally gained in educational laboratories. Over the years, however, the nature of these laboratories has changed. This paper describes the history of some of these changes and explores in some depth a few of the major factors influencing laboratories today. In particular, the paper considers the lack of coherent learning objectives for laboratories and how this lack has limited the effectiveness of laboratories and hampered meaningful research in the area. A list of fundamental objectives is presented along with suggestions for possible future research.  相似文献   

14.
Human Factors and Ergonomics (HFE) recognises itself as a design-driven, systemic and scientific discipline geared towards well-being and performance. Being a scientific discipline and design-oriented requires that the epistemic basis of science and design/engineering be fully comprehended. In interdisciplinary research where these two viewpoints meet, there are often dilemmas posed in terms of knowledge construction and labelling of activity. Therefore, this article scrutinises these two orientations and addresses the differences and commonalities, using case studies from engineering and psychological science (both constituents of HFE). Based on these insights, a way forward is suggested in terms of (1) a reflexive engagement with epistemic concepts and methods; (2) finding a conceptual space for balancing and bridging the science-engineering divide; (3) comprehending ‘design-thinking/design knowledge’ and not treating it as an application of science; (4) providing emphasis on problem formulation and practices of HFE focusing on developing them in systemic terms.  相似文献   

15.
Current drug treatments for post-menopausal osteoporosis cannot eliminate bone fractures, possibly because the mechanisms responsible for bone loss are not fully understood. Although research within various disciplines has significantly advanced the state of knowledge, fundamental findings are not widely understood between different disciplines. For that reason, this paper presents noteworthy experimental findings from discrete disciplines focusing on post-menopausal osteoporosis. These studies have established that, in addition to bone loss, significant changes in bone micro-architecture, tissue composition and micro-damage occur. Cellular processes and molecular signalling pathways governing pathological bone resorption have been identified to a certain extent. Ongoing studies endeavour to determine how such changes are initiated at the onset of oestrogen deficiency. It emerges that, because of the discrete nature of previous research studies, the sequence of events that lead to bone fracture is not fully understood. In this paper, two sequences of multi-scale changes are proposed and the experimental challenges that need to be overcome to fully define this sequence are outlined. Future studies must comprehensively characterize the time sequence of molecular-, cellular- and tissue-level changes to attain a coherent understanding of the events that ultimately lead to bone fracture and inform the future development of treatments for post-menopausal osteoporosis.  相似文献   

16.
输电塔线体系是重要的电力能源基础设施,长期于野外恶劣环境下服役,其高柔特性使得它在强烈外荷载作用下的响应较为显著。国内外发生了很多输电线路在强风强震、覆冰、腐蚀等作用下的破坏事故,造成了严重的损失。因此,国内外积极开展了输电线路的监测评估与防灾减灾的研究和工程应用工作。输电塔线体系力学模型的建立是开展输电线路监测评估和防灾减灾的基础和关键。输电线从力学角度而言是具有小应变、大变形特征的悬索,表现出显著的几何非线性效应。输电塔线体系的力学模型相比于传统高耸塔架结构而言非常复杂,它综合了有限元、随机振动、变分理论、风工程、地震工程、结构分析理论等多学科理论,相关研究工作还不完善。该文以输电塔线体系的力学模型为研究对象,全面综述了目前塔线体系力学模型方面的研究现状,对比分析了不同模型的优缺点,总结了该研究方面存在的不足并就将来的发展进行了展望。  相似文献   

17.
Learning conceptual knowledge in engineering science is a critical element in the development of competence and expertise in engineering. To date, however, research on conceptual learning in engineering science has been limited. Therefore, this article draws heavily on fundamental research by cognitive psychologists and applied research by science educators to provide a background on fundamental issues in the field and methods for assessing conceptual knowledge. Some of the most common conceptual difficulties from three domains: mechanics, thermal science and direct current electricity, are discussed to provide concrete examples of what students find difficult to learn. The article concludes with a discussion of possible sources of these difficulties, implications for instruction, and suggestions for future research.  相似文献   

18.
In order to implement the Accreditation Board for Engineering and Technology (ABET) engineering criteria, it is important for engineering educators to understand different types of knowledge and how these types relate to the outcomes described in Criterion 3. This paper first provides a heuristic for framing a program's educational objectives by identifying exemplars of the types of engineers a program seeks to graduate. Three sections then follow, each addressing categories of knowledge: tacit knowledge, four types of knowledge that can either be tacit or explicit, and knowledge created and shared in teams. Examples of the relationship of traits of knowledge to the outcomes in Criterion 3 are provided. The paper concludes with a brief discussion of how these types of knowledge are imbued in engineering students at the University of Virginia, as well as suggestions for additional ways in which they could be infused into engineering curricula.  相似文献   

19.
This paper links development approaches with innovation systems theory and social inclusion concerns. In exploring the relationship between development and knowledge, we propose a sequential analytical model that considers values, facts and policies as a coherent whole. This allows us to go deeper into the question of how policies for promoting the production and use of knowledge able to foster different facets of social inclusion can be formulated and implemented. We propose to call such policies “democratization of knowledge policies”; they are one of the means to achieve inclusive development. We provide examples of how these policies work in practice, and explore how the university, a vital part of any national innovation system, can play a role in the emergence and consolidation of the democratization of knowledge. Universities that embrace that role may be considered developmental universities. They fulfill it in great part by providing effective incentives to include in their research agendas the kind of problems whose solutions can lead to an enhancement of social inclusion. However, developmental universities cannot function in isolation. It is argued that their effectiveness depends on the rise of a sustained and strong demand that is able to put knowledge at the direct service of shared social goals, among which diminishing inequality is particularly important. The paper presents a case in Uruguay that illustrates an ongoing transformation towards a developmental university.  相似文献   

20.
Building information modeling/management (BIM) is an emerging technological and procedural shift in the architecture, engineering, construction and operation industry. In this study, we use an extensive state-of-the-art method to clarify the BIM adoption process and the factors that can influence the success or failure of BIM adoption, particularly during the implementation stage, which are not frequently found in the literature. As an innovation, the lexical field allocated to the spread of innovations is assigned to BIM (diffusion, adoption, and implementation). After recalling the definition of relevant terms and then removing the resulting inconsistencies in vocabularies, we investigate various studies to identify factors that influence BIM adoption and then unify all these studies in one coherent and consistent BIM adoption process model. We focus on factors that play a role in the adoption of BIM in small- and medium-sized enterprises (SMEs) because SMEs constitute the majority of companies in the construction sector. This research highlights and intends to fill in some gaps found in the current BIM adoption literature.  相似文献   

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