Progress towards the design and numerical analysis of a 3D microchannel biochip separator

This paper reports the design and numerical analysis of a three-dimensional biochip plasma blood separator using computational fluid dynamics techniques. Based on the initial configuration of a two-dimensional (2D) separator, five three-dimensional (3D) microchannel biochip designs are categorically developed through axial and plenary symmetrical expansions. These include the geometric variations of three types of the branch side channels (circular, rectangular, disc) and two types of the main channel (solid and concentric). Ignoring the initial transient behaviour and assuming that steady-state flow has been established, the behaviour of the blood fluid in the devices is algebraically analysed and numerically modelled. The roles of the relevant microchannel mechanisms, i.e. bifurcation, constriction and bending channel, on promoting the separation process are analysed based on modelling results. The differences among the different 3D implementations are compared and discussed. The advantages of 3D over 2D separator in increasing separation volume and effectively depleting cell-free layer fluid from the whole cross section circumference are addressed and illustrated. © 2011 John Wiley & Sons, Ltd.

Unified modelling in support of organization design and change

The aim of this research is to provide a unified modelling-based method to help with the evaluation of organization design and change decisions. Relevant literature regarding model-driven organization design and change is described. This helps identify the requirements for a new modelling methodology. Such a methodology is developed and described. The three phases of the developed method include the following. First, the use of CIMOSA-based multi-perspective enterprise modelling to understand and capture the most enduring characteristics of process-oriented organizations and externalize various types of requirement knowledge about any target organization. Second, the use of causal loop diagrams to identify dynamic causal impacts and effects related to the issues and constraints on the organization under study. Third, the use of simulation modelling to quantify the effects of each issue in terms of organizational performance. The design and case study application of a unified modelling method based on CIMOSA (computer integrated manufacturing open systems architecture) enterprise modelling, causal loop diagrams, and simulation modelling, is explored to illustrate its potential to support systematic organization design and change. Further application of the proposed methodology in various company and industry sectors, especially in manufacturing sectors, would be helpful to illustrate complementary uses and relative benefits and drawbacks of the methodology in different types of organization. The proposed unified modelling-based method provides a systematic way of enabling key aspects of organization design and change. The case company, its relevant data, and developed models help to explore and validate the proposed method. The application of CIMOSA-based unified modelling method and integrated application of these three modelling techniques within a single solution space constitutes an advance on previous best practice. Also, the purpose and application domain of the proposed method offers an addition to knowledge. © IMechE 2009.

Design and testing of a 250 kW medium-speed Brushless DFIG

This paper presents the design and testing of a 250 kW medium-speed Brushless Doubly-Fed Induction Generator (Brushless DFIG), and its associated power electronics and control systems. The experimental tests confirm the design, and show the system's steady-state and dynamic performance. The medium-speed Brushless DFIG in combination with a simplified two-stage gearbox promises a low-cost low-maintenance and reliable drive train for wind turbine applications.

Design and simulation of SMES system using YBCO tapes for direct drive wave energy converters

The ocean represents a huge energy reservoir since waves can be exploited to generate clean and renewable electricity; however, a hybrid energy storage system is needed to smooth the fluctuation. In this paper a hybrid energy storage system using a superconducting magnetic energy system (SMES) and Li-ion battery is proposed. The SMES is designed using Yttrium Barium Copper Oxide (YBCO) tapes, which store 60 kJ electrical energy. The magnet component of the SMES is designed using global optimization algorithm. Mechanical stress, coupled with electromagnetic field, is calculated using COMSOL and Matlab. A cooling system is presented and a suitable refrigerator is chosen to maintain a cold working temperature taking into account four heat sources. Then a microgrid system of direct drive linear wave energy converters is designed. The interface circuit connecting the generator and storage system is given. The result reveals that the fluctuated power from direct drive linear wave energy converters is smoothed by the hybrid energy storage system. The maximum power of the wave energy converter is 10 kW. © 2012 IEEE.

Climate resilience of schools: a case study

Social and political concerns are frequently reflected in the design of school buildings, often in turn leading to the development of technical innovations. One example is a recurrent concern about the physical health of the nation, which has at several points over the last century prompted new design approaches to natural light and ventilation. The most critical concern of the current era is the global, rather than the indoor, environment. The resultant political focus on mitigating climate change has resulted in new regulations, and in turn considerable technical changes in building design and construction. The vanguard of this movement has again been in school buildings, set the highest targets for reducing operational carbon by the previous Government. The current austerity measures have moved the focus to the refurbishment and retrofit of existing buildings, in order to bring them up to the exacting new standards. Meanwhile there is little doubt that climate change is happening already, and that the impacts will be considerable. Climate scientists have increasing confidence in their predictions for the future; if today’s buildings are to be resilient to these changes, building designers will need to understand and design for the predicted climates in order to continue to provide comfortable and healthy spaces through the lifetimes of the buildings. This paper describes the decision processes, and the planned design measures, for adapting an existing school for future climates. The project is at St Faith’s School in Cambridge, and focuses on three separate buildings: a large Victorian block built as a substantial domestic dwelling in 1885, a smaller single storey 1970s block with a new extension, and an as-yet unbuilt single storey block designed to passivhaus principles and using environmentally friendly materials. The implications of climate change have been considered for the three particular issues of comfort, construction, and water, as set out in the report on Design for Future Climate: opportunities for adaptation in the built environment (Gething, 2010). The adaptation designs aim to ensure each of the three very different buildings remains fit for purpose throughout the 21st century, continuing to provide a healthy environment for the children. A forth issue, the reduction of carbon and the mitigation of other negative environmental impacts of the construction work, is also a fundamental aim for the school and the project team. Detailed modelling of both the operational and embodied energy and carbon of the design options is therefore being carried out, in order that the whole life carbon costs of the adaptation design options may be minimised. The project has been funded by the Technology Strategy Board as part of the Design for Future Climates programme; the interdisciplinary team includes the designers working on the current school building projects and the school bursar, supported by researchers from the University of Cambridge Centre for Sustainable Development. It is hoped that lessons from the design process, as well as the solutions themselves, will be transferable to other buildings in similar climatic regions.

Design and characteristion of a hydraulic microactuator fabricated by lithography

To improve the force output of microactuators, this work focuses on actuators driven by pressurized gasses or liquids. Despite their well known ability to generate high actuation forces, hydraulic actuators remain uncommon in microsystems. This is both due to the difficulty of fabricating these microactuators with the existing micromachining processes and to the lack of adequate microseals. This paper describes how to overcome these limitations with a combination of anisotropic micromachining, UV definable polymers and low temperature bonding. The functionality of these actuators is proven by extensive measurements which showed that actuation forces of 0.1 N can be achieved for actuators with an active cross-section of 0.15 mm2. This is an order of magnitude higher than what is reported for classic MEMS actuators of similar size.

Design and testing of an ortho-planar micro-valve

This paper presents the production and testing of an ortho-planar one-way micro-valve. The main advantages of such valves are that they are very compact and can be made from a single flat piece of material. A previous paper presents and discusses a micro-valve assembly based on a spider spring. The present paper focuses on the valve assembly process and the valve performance.. Several prototypes with a bore of 0.2 mm have been built using two manufacturing techniques (μEDM and stereo-lithography) and tested for pressures up to 7 bars. © 2008 International Federation for Information Processing.

Design and Performance Analysis of a 2.5 MW-Class HTS Synchronous Motor for Ship Propulsion

The development of cryogenic technology and high temperature superconducting (HTS) materials has seen continued interest worldwide in the development of HTS machines since the late 1980s. In this paper, the authors present a conceptual design of a 2.5 MW class synchronous motor. The structure of the motor is specified and the motor performance is analyzed via a three-dimensional model using the finite element method (FEM). Rotor optimization is carried out to decrease the harmonic components in the air gap field generated by HTS tapes. Based on the results of this 3D simulation, the determination of the operating conditions and load angle is discussed with consideration to the HTS material properties. The economic viability of air-core and iron-core designs is compared. The results show that this type of HTS machine has the potential to achieve an economic, efficient and effective machine design, which operates at a low load angle, and this design process provides a practical way to simulate and analyze the performance of such machines.