A temperature sensor from a self-assembled carbon nanotube microbridge

Recent studies show that carbon nanotubes (CNTs) can be used as temperature sensors, and offer great opportunities towards extreme miniaturization, high sensitivity, low power consumption, and rapid response. Previous CNT based temperature sensors are fabricated by either dielectrophoresis or piece-wise alignment of read-out electronics around randomly dispersed CNTs. We introduce a new deterministic and parallel microsensor fabrication method based on the self-assembly of CNTs into three-dimensional microbridges. We fabricated prototype microbridge sensors on patterned electrodes, and found their sensitivity to be better than -0.1 %/K at temperatures between 300K and 420K. This performance is comparable to previously published CNT based temperature sensors. Importantly, however, our research shows how unique sensor architectures can be made by self-assembly, which can be achieved using batch processing rather than piecewise assembly. ©2010 IEEE.

Towards a fast electro-thermo-mechanical IGBT/Diode simulation framework for design of reliable power electronic converters

This paper describes a methodology that enables fast and reasonably accurate prediction of the reliability of power electronic modules featuring IGBTs and p-i-n diodes, by taking into account thermo-mechanical failure mechanisms of the devices and their associated packaging. In brief, the proposed simulation framework performs two main tasks which are tightly linked together: (i) the generation of the power devices' transient thermal response for realistic long load cycles and (ii) the prediction of the power modules' lifetime based on the obtained temperature profiles. In doing so the first task employs compact, physics-based device models, power losses lookup tables and polynomials and combined material-failure and thermal modelling, while the second task uses advanced reliability tests for failure mode and time-to-failure estimation. The proposed technique is intended to be utilised as a design/optimisation tool for reliable power electronic converters, since it allows easy and fast investigation of the effects that changes in circuit topology or devices' characteristics and packaging have on the reliability of the employed power electronic modules. © 2012 IEEE.

Metal-polymer composite sensors for volatile organic compounds: Part 1. Flow-through chemi-resistors

A new type of chemi-resistor based on a novel metal-polymer composite is described. The composite contains nickel particles with sharp nano-scale surface features, which are intimately coated by the polymer matrix so that they do not come into direct physical contact. No conductive chains of filler particles are formed even at loadings above the percolation threshold and the composite is intrinsically insulating. However, when subjected to compression the composite becomes conductive, with sample resistance falling from ≥ 1012 Ω to < 0.01 Ω. The composite can be formed into insulating granules, which display similar properties to the bulk form. A bed of granules compressed between permeable frits provides a porous structure with a start resistance set by the degree of compression while the granules are free to swell when exposed to volatile organic compounds (VOCs). The granular bed presents a large surface area for the adsorption of VOCs from the gas stream flowing through it. The response of this system to a variety of vapours has been studied for two different sizes of the granular bed and for different matrix polymers. Large responses, ΔR/R0 ≥ 10^7, are observed when saturated vapours are passed through the chemi-resistor. Rapid response allows real time sensing of VOCs and the initial state is recovered in a few seconds by purging with an inert gas stream. The variation in response as a function of VOC concentration is determined.

Robust multiplexed MPC for distributed multi-agent systems

This paper extends the authors' earlier work which adapted robust multiplexed MPC for application to distributed control of multi-agent systems with non-interacting dynamics and coupled constraint sets in the presence of persistent unknown, but bounded disturbances. Specifically, we propose exploiting the single agent update nature of the multiplexed approach, and fix the update sequence to enable input move-blocking and increased discretisation rates. This permits a higher rate of individual policy update to be achieved, whilst incurring no additional computational cost in the corresponding optimal control problems to be solved. A disturbance feedback policy is included between updates to facilitate finding feasible solutions. The new formulation inherits the property of rapid response to disturbances from multiplexing the control and numerical results show that fixing the update sequence does not incur any loss in performance. © 2011 IFAC.

The Place of Philosophy in Management

Our purpose is to not to define a particular philosophy of management, but rather to demonstrate some of the ways in which philosophy – ethics, metaphysics, epistemology, logic and æsthetics – contributes to the practice of management. We identify a number of contemporary management questions, procedures or issues where the application of philosophical approaches are relevant, and show how philosophical skills, an understanding of philosophical principles or exposure to philosophical discussion can contribute to improved management practice. In some ways the paper is a report on progress in the quest begun by Nigel Laurie and Christopher Cherry in the first issue of Philosophy of Management, formerly Reason in Practice (2001) when they asked why philosophers have interested themselves so little in the entire field of management. We include some examples where philosophers have written about management, some where managers have shown the direct impact of philosophy on management effectiveness and some where potential remains. In much we see links to process philosophy, and to the need for conversation and reflection by and between managers and philosophers. This does not of itself show how philosophy can contribute to management education. A brief final section discusses the way in which moral creativity skills can be developed through reflection, and describes how this has been done in the Manufacturing Leaders’ Programme at the Institute for Manufacturing at Cambridge and in the International Management Ethics & Values course taught to undergraduate management students in Adelaide, Singapore and Hong Kong. This will be taken up in a subsequent paper.