Investigation of electrostrictive polymers as actuators for mesoscale devices

Abstact This paper presents an investigation of the use of electrostrictive silicone polymers as actuators for mesoscale devices. The generated strains of both flat and rolled actuators, based on Dow Corning Sylgard 182 and 184, with sputtered gold electrodes, are presented as functions of the applied electric field. Variables examined in this study include silicone film thickness, gold electrode thickness, cycling of the applied electric field, and actuator configuration (flat or rolled). In general, thinner silicone films and gold electrodes yielded greater strains, at a constant applied field. The actuator performance tended to deteriorate with repeated application of the electric field, and the gold electrodes cracked after being subjected to a large percentage strain.Nomenclature A Cross sectional area, mm² - a ₁ , a ₂ electrostrictive constants, m²/V² - D diameter, mm - E electric field, V/m - _o permittivity of free space, F/m - dielectric constant for silicones, F/m - F force, N - J work, J - l length, m - S _ij strain tensor, dimensionless - S _ijkl tensor of elastic compliance coefficients, m - t thickness, m - T _kl stress tensor, Pa - u _i displacement vector, mm - V volume, mm³ - Poisson ratio, dimensionless - w width, m - Y Youngs modulus, Pa     

Welfare or Work? Low-Income Working Households' Housing Consumption in the Private Rented Sector in England

This paper is concerned with issues of equity and efficiency in the Housing Benefit (HB) system in the private rented sector (PRS) in England. Using information from a survey of low- income working households (LIWH) and in-depth interviews with LIWH families, it addresses two policy-relevant questions. First, there are mixed findings on whether the current HB system enables HB recipients to consume more housing than is available to otherwise similar non-HB-recipient households in the PRS. HB rules on eligible property size appear not to unduly favour HB claimants compared with LIWH. LIWH, however, tend to pay a rent which is less than the maximum amount an HB recipient could receive. This is particularly true for LIWH families with children who are most likely to be living in properties smaller than allowed by HB regulations. Second, there is no evidence that the HB system incentivises LIWH to give up work or otherwise seek to become eligible for HB.     

Enhanced mass transport in nanofluids

Thermal conductivity enhancement in nanofluids, which are liquids containing suspended nanoparticles, has been attributed to localized convection arising from the nanoparticles' Brownian motion. Because convection and mass transfer are similar processes, the objective here is to visualize dye diffusion in nanofluids. It is observed that dye diffuses faster in nanofluids compared to that in water, with a peak enhancement at a nanoparticle volume fraction, phi, of 0.5%. A possible change in the slope of thermal conductivity enhancement at that same phi signifies that convection becomes less important at higher phi. The enhanced mass transfer in nanofluids can be utilized to improve diffusion in microfluidic devices.     

Grammatical evolution in developing optimal inventory policies for serial and distribution supply chains

Recently, there has been a growing literature on biologically inspired algorithms, particularly genetic algorithms and genetic programming, applied to supply chain modelling and inventory control optimisation. Due to the rigidity of the genetic algorithms approach, it is difficult to change the underlying model logic and add richness to the supply chain. While genetic programming provides a more flexible approach than that provided by genetic algorithms, to date its application has been limited to small supply chain modelling problems in relation to optimal inventory policies. This research applies Grammatical Evolution, a relatively new biologically inspired algorithm, to the field of supply chain optimisation, employing human readable rules called grammars. These grammars provide a single mechanism to describe a variety of complex structures and can incorporate the domain knowledge of the practitioner to bias the algorithm towards regions of the search space containing better solutions. Results are presented showing Grammatical Evolution is at least competitive in cost terms, and superior in flexibility, with these methods applicable to any supply chain of the serial or distribution type. Furthermore, Grammatical Evolution shows an adaptive ability that augurs well for supply chains in dynamic environments, such as disruption.     

Application of high-throughput computing in bioinformatics

We describe the challenges faced when developing a Linux/PC-based cluster to apply bioinformatics algorithms to the rapidly increasing raw genomics data available. The calculations, which take around two months to complete, result in a powerful resource that can be used for data mining--most obviously for the human genome. Our current infrastructure consists of a 1314 node cluster with 1734 processors supporting both production and research. This paper highlights the problems in achieving high data throughput with such systems and shows that raw computer power is only one component of a complex problem.     

Thermal analysis and phase evolution of ferroelectric PbTiO<Subscript>3</Subscript> obtained from silicate and borate based glasses

This article assessed the glass formability for crystallization of lead titanate (PbTiO₃) as the primary phase. It was found that silicate-based glasses formed glass as a block without the need for cold splatting, but B₂O₃-based glasses needed to be prepared by cold splatting to retard devitrification. Also, incorporation of BaO was favoured by an increase in the concentration of B₂O₃. DTA showed the crystallization of crystalline phases occurred above glass transition temperature. XRD traces supported the DTA data where the first exothermic peak in each case was presumed to be related to the crystallization of PbTiO₃ (PT) phase. XRD also showed the lower c/a ratios compared to pure PT ceramic, which suggested three possibilities for lower values: crystal clamping by the rigid glass matrix, intrinsic size effect and incorporation of impurities in the PT phase.     

Effect of XRD relative intensities of the Li (002) on surface,optical and electrochemical impedance spectroscopy analyses of the deposited LiCoO<Subscript>2</Subscript> thin film

In this paper, the effect of RF power on LiCoO₂ thin films was investigated using X-ray diffractometer (XRD), atomic force microscopy, UV–Vis spectrophotometer, and potentiostat. The microstructural, surface, optical and electrochemical impedance measurements were performed to LiCoO₂ thin films, are used to for the fully solid-state battery cathode material. According to obtained results, the relative intensities of the Li (002) crystal phase in XRD patterns of deposited LiCoO₂ thin films were increased by increasing applied RF power, for the first time. The intensity of the LiCoO₂ (104) plane is nearly invariant. The relative intensities of the LiCoO₂ (113) plane were decreased by increasing RF power. The peak locations of the Li (002) and LiCoO₂ (104) were not changed. It was found that Li (002) relative intensities affect the all investigated parameters for the LiCoO₂ thin films. Especially, transmittance value increased about 20%. The band gap of the deposited film was changed 100–300 meV drastically. Deposited samples are shown high transparency in the visible region. Randles circuit was used for the equivalent circuit model. Nyquist plots, fitting parameters values and value of the circuit elements were estimated by ZSim software.