B. Fiegl, M. Hibler, W. Kiffe, F. Koch, R. Kuhnert, R. Messer and H. Schwarzbauer
Module technology has become the most successful technology for power devices. The sandwich structure of the module serves as both an electrical insulator and heat sink to remove…
Abstract
Module technology has become the most successful technology for power devices. The sandwich structure of the module serves as both an electrical insulator and heat sink to remove the heat generated in the device. Typical heat fluxes of 200 W/cm2 through the chip substrate interface make it necessary to develop modules with a lower thermal resistance than those available today. With the recent advances in diamond technology, diamond substrates which have unique heat conducting properties are now available. Presented here are the first applications of diamond films in power device modules in combination with a new joining technology. The thermal behaviour of these modules has been simulated. Following the simulations, power device modules with a diamond film were produced. Investigations with a scanning acoustic microscope showed that there is good mechanical contact between the diamond and the adjacent layers. The thermal resistance of the modules was measured. The results are in good agreement with those of the simulations. They show that the application of diamond films in power modules for heat conduction and heat spreading is feasible. It is demonstrated that diamond films together with an advanced joining technology provide a considerable improvement in thermal management compared with state‐of‐the‐art technologies.
Parviz Moradipour, Jamaloddin Noorzaei, Mohd Saleh Jaafar and Farah Nora Aznieta Abdul Aziz
In structural, earthquake and aeronautical engineering and mechanical vibration, the solution of dynamic equations for a structure subjected to dynamic loading leads to a high…
Abstract
Purpose
In structural, earthquake and aeronautical engineering and mechanical vibration, the solution of dynamic equations for a structure subjected to dynamic loading leads to a high order system of differential equations. The numerical methods are usually used for integration when either there is dealing with discrete data or there is no analytical solution for the equations. Since the numerical methods with more accuracy and stability give more accurate results in structural responses, there is a need to improve the existing methods or develop new ones. The paper aims to discuss these issues.
Design/methodology/approach
In this paper, a new time integration method is proposed mathematically and numerically, which is accordingly applied to single-degree-of-freedom (SDOF) and multi-degree-of-freedom (MDOF) systems. Finally, the results are compared to the existing methods such as Newmark's method and closed form solution.
Findings
It is concluded that, in the proposed method, the data variance of each set of structural responses such as displacement, velocity, or acceleration in different time steps is less than those in Newmark's method, and the proposed method is more accurate and stable than Newmark's method and is capable of analyzing the structure at fewer numbers of iteration or computation cycles, hence less time-consuming.
Originality/value
A new mathematical and numerical time integration method is proposed for the computation of structural responses with higher accuracy and stability, lower data variance, and fewer numbers of iterations for computational cycles.
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The purpose of this paper is to show how particle scale simulation of industrial particle flows using DEM (discrete element method) offers the opportunity for better understanding…
Abstract
Purpose
The purpose of this paper is to show how particle scale simulation of industrial particle flows using DEM (discrete element method) offers the opportunity for better understanding of the flow dynamics leading to improvements in equipment design and operation.
Design/methodology/approach
The paper explores the breadth of industrial applications that are now possible with a series of case studies.
Findings
The paper finds that the inclusion of cohesion, coupling to other physics such fluids, and its use in bubbly and reacting flows are becoming increasingly viable. Challenges remain in developing models that balance the depth of the physics with the computational expense that is affordable and in the development of measurement and characterization processes to provide this expanding array of input data required. Steadily increasing computer power has seen model sizes grow from thousands of particles to many millions over the last decade, which steadily increases the range of applications that can be modelled and the complexity of the physics that can be well represented.
Originality/value
The paper shows how better understanding of the flow dynamics leading to improvements in equipment design and operation can potentially lead to large increases in equipment and process efficiency, throughput and/or product quality. Industrial applications can be characterised as large, involving complex particulate behaviour in typically complex geometries. The critical importance of particle shape on the behaviour of granular systems is demonstrated. Shape needs to be adequately represented in order to obtain quantitative predictive accuracy for these systems.
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Particle scale simulation of industrial particle flows using discrete element method (DEM) offers the opportunity for better understanding the flow dynamics leading to…
Abstract
Particle scale simulation of industrial particle flows using discrete element method (DEM) offers the opportunity for better understanding the flow dynamics leading to improvements in equipment design and operation that can potentially lead to large increases in equipment and process efficiency, throughput and/or product quality. Industrial applications can be characterized as large, involving complex particulate behaviour in typically complex geometries. In this paper, with a series of examples, we will explore the breadth of large scale modelling of industrial processes that is currently possible. Few of these applications will be examined in more detail to show how insights into the fundamentals of these processes can be gained through DEM modelling. Some examples of our collaborative validation efforts will also be described.
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Dawei Zhao, Erfan G. Nezami, Youssef M.A. Hashash and Jamshid Ghaboussi
Develop a new three‐dimensional discrete element code (BLOKS3D) for efficient simulation of polyhedral particles of any size. The paper describes efficient algorithms for the most…
Abstract
Purpose
Develop a new three‐dimensional discrete element code (BLOKS3D) for efficient simulation of polyhedral particles of any size. The paper describes efficient algorithms for the most important ingredients of a discrete element code.
Design/methodology/approach
New algorithms are presented for contact resolution and detection (including neighbor search and contact detection sections), contact point and force detection, and contact damping. In contact resolution and detection, a new neighbor search algorithm called TLS is described. Each contact is modeled with multiple contact points. A non‐linear force‐displacement relationship is suggested for contact force calculation and a dual‐criterion is employed for contact damping. The performance of the algorithm is compared to those currently available in the literature.
Findings
The algorithms are proven to significantly improve the analysis speed. A series of examples are presented to demonstrate and evaluate the performance of the proposed algorithms and the overall discrete element method (DEM) code.
Originality/value
Long computational times required to simulate large numbers of particles have been a major hindering factor in extensive application of DEM in many engineering applications. This paper describes an effort to enhance the available algorithms and further the engineering application of DEM.
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The purpose of this paper is to provide an explanation for the global influences and dynamics that have led major mining companies to adopt corporate social responsibility (CSR…
Abstract
Purpose
The purpose of this paper is to provide an explanation for the global influences and dynamics that have led major mining companies to adopt corporate social responsibility (CSR) policies, and frame them in terms of sustainable development. Bad reputations stemming from environmental disasters and social disharmony led mining multinationals to adopt CSR policies and improve their practices. Rationalist expectations about what is driving firm responses to external pressures are a necessary, but insufficient, explanation of how and why mining companies have sought to improve their reputations. Three elements are necessary to explain firm responses, including strategic adaptation to external pressures, learning processes associated with CSR, and internalization of sustainable development norms, understood as standards of appropriate behavior.
Design/methodology/approach
The paper presents a multidisciplinary theoretical framework for explaining the adoption of CSR policies and practices on the part of mining companies, and applies that framework to case studies of two major mining companies with global operations.
Findings
An account of learning processes and norms socialization as they relate to CSR provide a more comprehensive explanation of how and why mining companies adopt CSR policies. Incorporation of these elements provides a better explanation of why mining companies began to frame their CSR policies in terms of the global norm of sustainable development.
Originality/value
The paper contributes to the theoretical understanding of how and why firms adapt to changing societal expectations about appropriate corporate behavior by integrating two sets of literatures; constructivism from international relations theory, and learning from organization theory.
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Barbara S. Tint, Viv McWaters and Raymond van Driel
The purpose of this paper is to introduce applied improvisation (AI) as a tool for training humanitarian aid workers. AI incorporates principles and practices from improvisational…
Abstract
Purpose
The purpose of this paper is to introduce applied improvisation (AI) as a tool for training humanitarian aid workers. AI incorporates principles and practices from improvisational theatre into facilitation and training. It is an excellent modality for training aid workers to deal with crisis and disaster scenarios where decision-making and collaboration under pressure are critical.
Design/methodology/approach
This paper provides a theoretical base for understanding skills needed in disaster response and provides a case for innovative training that goes beyond the current standard. AI principles, activities and case examples are provided. Interviews with development experts who have participated in AI training are excerpted to reveal the impact and promise of this methodology.
Findings
Different from typical training and games, which simulate potential crisis scenarios, AI works with participants in developing the skills necessary for success in disaster situations. The benefit is that workers are better prepared for the unexpected and unknown when they encounter it.
Research limitations/implications
The current paper is based on author observation, experience and participant interviews. While AI is consistently transformative and successful, it would benefit from more rigorous and structured research to ground the findings more deeply in larger evidence based processes.
Practical implications
The authors offer specific activities, resources for many others and practical application of this modality for training purposes.
Social implications
Its application has tremendous benefits in training for specific skills, in creating greater cohesion and satisfaction in work units and breaking down culture and language barriers.
Originality/value
This work is original in introducing these training methods to humanitarian aid contexts in general, and disaster preparedness and response in particular.
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UNTIL now the field of clerical work is one which has been cultivated only marginally by work study methods. When the Prices and Incomes Board examined pay agreements in that…
Abstract
UNTIL now the field of clerical work is one which has been cultivated only marginally by work study methods. When the Prices and Incomes Board examined pay agreements in that sector of British business it was constrained to comment that ‘the application of measurement techniques to clerical work still has a long way to go’.
The ice pack covering the Arctic basin is composed of a multitude of ice parcels of different areas, ages, thicknesses, and deformation histories that are frozen together into…
Abstract
The ice pack covering the Arctic basin is composed of a multitude of ice parcels of different areas, ages, thicknesses, and deformation histories that are frozen together into larger plates that combine and break apart in response to the demands of ever changing boundary conditions and forcing. Current Arctic sea ice models are Eulerian continuum models that use a plastic yield surface to characterize the constitutive behavior of the pack. An alternative is to adopt a discontinuous Lagrangian approach, based on a discrete element model and explicitly simulate individual ice parcels and the interactions between them. The mechanics of the Lagrangian sea ice model are outlined in detail along with the methods that will be used for validation.
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Our planning systems are predicated upon a variety of myths. One of the most cherished is the myth of stability: “Business as usual” is a very comforting notion. Organizations…
Abstract
Our planning systems are predicated upon a variety of myths. One of the most cherished is the myth of stability: “Business as usual” is a very comforting notion. Organizations everywhere enjoy the feeling of safety that develops when change is slow. Planners are usually directed to the task of preserving the existing “stable system” and maintaining the status quo. The alternatives — deliberately modifying the system or allowing it to evolve — are not often contemplated.