Effect of thermal radiation on natural convection over cylinders of elliptic cross section

Summary The effect of conduction-radiation on natural convection flow of an optically dense viscous incompressible fluid along an isothermal cylinder of elliptic cross section has been investigated. The boundary layer equations governing the flow are shown to be nonsimilar. Full numerical solutions of the governing equations are obtained using the implicit finite difference method. The solutions are expressed in terms of the Nusselt number Nu against the eccentric angle in the range [0, ]. The working fluid is taken to have unit value of the Prandtl number, Pr, and the effects of varying the Planck number,R _d, the surface temperature parameter, _w, and the parameterA _O representing the ratio of the major and minor axes of the cylinder are investigated. From the present analysis it is found that the rate of heat transfer from the slender body is higher than from the blunt body and that these higher values become even higher due to an increase in the effect of radiation in the flow field.Nomenclature a semi-major axis of the cylinder - a _r Rosseland mean absorption coefficient - b semi-minor axis of the cylinder - C _p specific heat at constant pressure - f dimensionless stream function - g acceleration due to gravity - Gr Grashof number - Nu Nusselt number - Q _w surface heat flux - Pr Prandtl number - R _d Planck number (radiation-conduction parameter) - T temperature of the fluid - T _w temperature of the heated surface - T temperature of the ambient fluid - u velocity in thex-direction - v velocity in they-direction - x coordinate measuring distance round the cylinder - y coordinate measuring distance normal to the cylinder Greek symbols eccentric angle - coefficient of cubial expansion - coefficient of thermal diffusivity - v kinematic viscosity     

High-Quality Volumetric Reconstruction on Optimal Lattices for Computed Tomography

Within the context of emission tomography, we study volumetric reconstruction methods based on the Expectation Maximization (EM) algorithm. We show, for the first time, the equivalence of the standard implementation of the EM-based reconstruction with an implementation based on hardware-accelerated volume rendering for nearest-neighbor (NN) interpolation. This equivalence suggests that higher-order kernels should be used with caution and do not necessarily lead to better performance. We also show that the EM algorithm can easily be adapted for different lattices, the body-centered cubic (BCC) one in particular. For validation purposes, we use the 3D version of the Shepp-Logan synthetic phantom, for which we derive closed-form analytical expressions of the projection data. The experimental results show the theoretically-predicted optimality of NN interpolation in combination with the EM algorithm, for both the noiseless and the noisy case. Moreover, reconstruction on the BCC lattice leads to superior accuracy, more compact data representation, and better noise reduction compared to the Cartesian one. Finally, we show the usefulness of the proposed method for optical projection tomography of a mouse embryo.     

ℋ 2 filtering of discrete-time Markov jump linear systems through linear matrix inequalities

This paper addresses the ?₂ filtering design problem of discrete-time Markov jump linear systems. First, under the assumption that the Markov parameter is measured, the main contribution is on the LMI characterisation of all filters such that the estimation error remains bounded by a given ?₂ norm level, yielding the complete solution of the mode-dependent filtering design problem. Based on this result, a robust filter design to deal with convex bounded parameter uncertainty is considered. Second, from the same LMI characterisation, a design procedure for mode-independent filtering design is proposed. Some examples are solved for illustration and comparison.     

Preparation of phenylboronic acid-based hydrogel microneedle patches for glucose-dependent insulin delivery

There is a problem with directly loading insulin into the polymerized glucose-responsive microneedle (MN) patch due to that polymerization conditions and solvents may damage the activity of insulin. In this study, we report a totally polymerized phenylboronic acid-based MN patch, and insulin was directly loaded in MNs by a mild drop/dry procedure. MN patch was prepared by copolymerization of N-isopropyl acrylamide, N-vinyl-2-pyrrolidone, and 3-acrylamidoephenylboronic acid in MN mold. The MN patch showed good glucose-dependent swelling behavior in pH 9.0 at 27°C. After insulin loading procedure, insulin was distributed on and within the MNs. About 43.2% of total insulin was diffused into MNs' interior. As a result, the release of insulin on MNs' surface was uncontrolled by MNs and rapidly finished after ~10 min. However, the release of insulin within MNs was depended on glucose concentration, and insulin was released 1.6 times more at 4 g/L than at 1 g/L glucose concentration after 12 h. Although further improvements are needed to make MN patch responding in physiological environment, this work suggests a solution for directly loading insulin in polymerized glucose-responsive MNs.     

Improvement of energy-handling capability of the ZnO varistors prepared by fractional precipitation on the seed materials

The improvement of the voltage gradient and energy-handling capability of the ZnO varistors is necessary for reliability and protection level in conjunction with the reduced mass of the surge arresters. The varistor processing variables were investigated and then energy-handling capabilities were evaluated. To reduce influence on the chemical co-precipitation process the method of fractional precipitation on seeds was used. In this study the influence of precipitant, dispersant, pH value, and temperature on the uniformity of the sediments and calcined additive powders was evaluated. It was observed that when the sediments were dried by the “half-dry” method via calcination in the range 600–650 °C, the calcined powders of the additives obtained had either no agglomeration or little agglomeration of the particles. The influence of the additive powders on spray dried granules and their forming were also studied. Eventually ZnO varistor blocks possessing varistor voltage gradient in the range 210∼260 V/mm and the energy handling capability of about 270 J/cm³ have been achieved.     

Evaluating the cost to industry of electricity outages

The unreliability of electricity supplies is a major cause of the high cost of manufacturing in developing countries. In this paper, we propose a more accurate approach, the contribution method, to measure the cost imposed by power outages. We employ a rich, if not unique, set of data from the detailed operating accounts of three large manufacturing enterprises in Nepal. Estimating the true opportunity costs to the enterprises from lost production caused by power outages sheds light on the issue of cost measurement that is critical for the determination of the feasibility of mitigating measures. Furthermore, having such micro-based information on the value of lost load per kWh by firm or sector is critical for reducing the economic costs of planned outages by the electric utility.     

iTCP: an intelligent TCP with neural network based end-to-end congestion control for ad-hoc multi-hop wireless mesh networks

Maintaining the performance of reliable transport protocols, such as transmission control protocol (TCP), over wireless mesh networks (WMNs) is a challenging problem due to the unique characteristics of data transmission over WMNs. The unique characteristics include multi-hop communication over lossy and non-deterministic wireless mediums, data transmission in the absence of a base station, similar traffic patterns over neighboring mesh nodes, etc. One of the reasons for the poor performance of conventional TCP variants over WMNs is that the congestion control mechanisms in conventional TCP variants do not explicitly account for these unique characteristics. To address this problem, this paper proposes a novel artificial intelligence based congestion control technique for reliable data transfer over WMNs. The synergy with artificial intelligence is established by exploiting a carefully designed neural network (NN) in the congestion control mechanism. We analyze the proposed NN based congestion control technique in detail and incorporate it into TCP to create a new variant that we name as intelligent TCP or iTCP. We evaluate the performance of iTCP using both ns-2 simulations and real testbed experiments. Our evaluation results demonstrate that our proposed congestion control technique exhibits a significant improvement in total network throughput and average energy consumption per transmitted bit compared to the congestion control techniques used in other TCP variants.     

煮羊肉不同组织低温贮藏品质特性的变化

为了深入研究煮制羊肉不同组织在低温贮藏期间的品质变化特征,本实验以煮制羊肉的瘦肉,肥瘦相间和肥肉部分为主要原材料,采用真空包装的方式,对其在4 ℃或低温下贮藏28 d（每隔1周取一次样）期间的pH、质构特征、色差、挥发性盐基氮（Total Volatile Base Nitrogen, TVB-N）、菌落总体数量及其感官评价等相关指标的变化进行了研究。结果显示:在4 ℃下贮藏,熟制羊肉不同组织的pH变化相似,都是呈现先下降后上升的趋势;肥肉的质构特性都高于瘦肉和肥瘦相间肉的特性;在贮藏期间,羊肉不同组织的L*值和a*值都表现为逐渐减小的趋势（P<0.05）,瘦肉的b*值表现为增大的趋势（P<0.05）,而肥瘦相间和肥肉都表现为减小的趋势（P<0.05);羊肉三种不同组织的挥发性盐基氮（Total Volatile Base Nitrogen,TVB-N）和菌落总数的含量则一直处于增加的状态,肥肉的增加速度及数量高于瘦肉和肥瘦相间组织,它们的感官评价都呈现逐渐下降的趋势。并且在贮藏时间达到14 d时,羊肉的品质已经发生腐败现象。结果表明,在贮藏期间瘦肉组织的品质更好。