Natural strategies for search

In recent years a considerable amount of natural computing research has been undertaken to exploit the analogy between, say, searching a given problem space for an optimal solution and the natural process of foraging for food. Such analogies have led to useful solutions in areas such as optimisation, prominent examples being ant colony systems and particle swarm optimisation. However, these solutions often rely on well defined fitness landscapes that are not always be available in more general search scenarios. This paper surveys a wide variety of behaviours observed within the natural world, and aims to highlight general cooperative group behaviours, search strategies and communication methods that might be useful within a wider computing context, beyond optimisation, where information from the fitness landscape may be sparse, but new search paradigms could be developed that capitalise on research into biological systems that have developed over millennia within the natural world.     

Optimization of the bistability property for flexible display by an integrated approach using Taguchi methods,neural networks and genetic algorithms

Flexible display has many advantages including lower power consumption, lighter weight, and thinness. Therefore, several companies strive to develop new applications for flexible displays to keep abreast of market opportunities. Flexible displays depend on the reflection of module processes; thus, its bistability should be improved to obtain a good vitality of optical whiteness characteristic. The current study applies an integrated approach to find the optimal settings of important control factors to determine effectively the settings of various different design parameters, thereby meeting closely the bistability targets. An actual case study is used to demonstrate the usefulness of the suggested approach for improving the bistability characteristic of flexible displays. The optical whiteness ratio has been improved from 20.79 to 28.24. Also, the case company shortened the improvement schedule effectively, regained customer orders, and earned revenues of approximately USD 32,000,000.     

Electrolyte stability determines scaling limits for solid-state 3D Li ion batteries

Rechargeable, all-solid-state Li ion batteries (LIBs) with high specific capacity and small footprint are highly desirable to power an emerging class of miniature, autonomous microsystems that operate without a hardwire for power or communications. A variety of three-dimensional (3D) LIB architectures that maximize areal energy density has been proposed to address this need. The success of all of these designs depends on an ultrathin, conformal electrolyte layer to electrically isolate the anode and cathode while allowing Li ions to pass through. However, we find that a substantial reduction in the electrolyte thickness, into the nanometer regime, can lead to rapid self-discharge of the battery even when the electrolyte layer is conformal and pinhole free. We demonstrate this by fabricating individual, solid-state nanowire core-multishell LIBs (NWLIBs) and cycling these inside a transmission electron microscope. For nanobatteries with the thinnest electrolyte, ≈110 nm, we observe rapid self-discharge, along with void formation at the electrode/electrolyte interface, indicating electrical and chemical breakdown. With electrolyte thickness increased to 180 nm, the self-discharge rate is reduced substantially, and the NWLIBs maintain a potential above 2 V for over 2 h. Analysis of the nanobatteries' electrical characteristics reveals space-charge limited electronic conduction, which effectively shorts the anode and cathode electrodes directly through the electrolyte. Our study illustrates that, at these nanoscale dimensions, the increased electric field can lead to large electronic current in the electrolyte, effectively shorting the battery. The scaling of this phenomenon provides useful guidelines for the future design of 3D LIBs.     

Photopolymerization of butyl acrylate-in-water microemulsions: Polymer molecular weight and end-groups

Solubilization of butyl acrylate in water using sodium dodecyl sulfate (SDS) and 1-pentanol produced transparent oil-in-water microemulsions stable at room temperature. These microemulsions were polymerized using a two-component water-soluble initiator system comprising of Rose Bengal (RB) and methyldiethanolamine (MDEA). These compounds undergo photo-induced electron transfer upon absorption of visible light to produce amine radicals active in free radical polymerization. Analysis of the NMR spectra of polymers revealed only monomer peaks and amine fragments which were incorporated as the polymer ends. Effect of initiator composition on polymer length was also investigated using GPC. When RB concentration was increased with constant concentration of excess MDEA, the average chain length decreased up to a specific concentration where after the polymer length reached an asymptotic value. Experiments were performed to identify this asymptotic value and it was observed that as the MDEA concentration was increased, the asymptotic values of number average degree of polymerization decreased.     

Evaporation rates of pure hydrocarbon liquids under the influences of natural convection and diffusion

Evaporation of liquid hydrocarbons was studied in order to better understand the relative influences of diffusion and buoyancy-induced convection of the vapors on the evaporation rate. Evaporation rates were measured using a simple gravimetric technique and the behavior of the vapor layer that quickly forms above the film was observed using schlieren imaging. Even for conditions for which the influence of buoyancy is strong, the evaporation rates are well correlated by a one-dimensional diffusion model if an effective vapor layer thickness is used.     

Deactivation of a Pt/Al2O3 catalyst during the oxidation of hexafluoropropylene

A 5% Pt/Al₂O₃ catalyst was exposed to hexafluoropropylene (HFP) at concentrations between 500 and 4,500 ppm in humid air at temperatures between 300 and 400°C. The catalyst was found to deactivate over all conditions investigated. Analysis of the catalyst following reaction exposure indicated that the catalyst support had been transformed to aluminum fluoride, and that virtually all of the support's surface area had been lost. The observed deactivation was attributed to degradation of the catalyst support, caused by a reaction between the alumina support and product hydrofluoric acid. Under some conditions, the rate of catalytic deactivation was found to be proportional to the number of moles of hexafluoropropylene reacted.     

Experiments and Modeling for Biocidal Effects of Explosives

This paper reports an experimental and modelling study of the biocidal effect of an energetic mixture which is detonated in a closed chamber containing an initial spore distribution. The resulting spore neutralization efficiency is recorded as a function of measured detonation and combustion performance. We also report the results of a range of numerical modelling studies carried out to aid the interpretation of these experiments and to guide future developments. We find that the current energetic mixture (aluminum powder which is shock dispersed by detonation of a central high explosive core) gives variable combustion efficiency. The Al powder ignites on impact with the walls. In the modelling we match the recorded quasi‐static pressures in each experiment and compare predicted spore neutralization with measured values. Using a critical spore temperature for neutralization of 670 K gives a good match to the experiments. We report how neutralization efficiency varies with changes to this temperature. The coupled experimental and modelling approach allows us to suggest requirements for future biocidal energetic materials.     

用于封装领域的高粘度流体微量喷射技术

在过去几年内，电子组装产业采用多种流体材料的步伐已经显著加快。在上世纪七十年代，芯片的封装仍然采用引线框架、芯片粘片、引线键合以及模塑料包封流程完成。印刷电路板（PCB）的组装则由波峰焊设备和IC贴片设备完成。其中涉及到流体涂敷的两步工艺是芯片粘结和暂时性的焊料掩模。随着混合组装和表面贴装技术（SMT）的增长，涉及到流体涂敷工艺的材料增加到焊膏、表面组装粘结剂、芯片粘贴材料、滴封材料、暂性焊料掩模以及芯片涂层材料。在上世纪八十年代后期，对更高速度更高性能器件的需求驱动半导体封装向面阵列封装发展，这又引入了坝式结构和填充材料、包封材料，倒装芯片用芯片底部填充料也首次得到大规模应用。随着市场的继续发展，要求产品具有更好的性能，尺寸更小、功耗更低、重量更轻、更符合环保要求、功能更强以及运行速度更快。这也引发了对流体材料、粘结剂、涂层材料、包封材料、焊膏和助焊剂的更多需求。     

The shock response,simulation and microstructural determination of a model composite material

The capability to assess microstructural details in a polymer matrix composite is important in addressing composite design for engineering applications. The generation of three-dimensional microstructure using a non-invasive high-resolution experimental diagnostics method will advance our knowledge within this field. An inert composite has been studied, and both X-ray microtomography (XRT) for microstructural investigation in 3D and a parallel series of shock experiments (with associated modelling) have been conducted. The experimental aims of this study lay in several areas: firstly, to adequately define the bulk morphology; secondly, to determine the geometry of defects within the material; and finally, to demonstrate a direct linkage with the mechanical response determined by finite element analysis. This work is the first step in finding a way to non-invasively link 3D microstructural invesigation and numerical simulation to predict the shock performance of a composite material.     

Therapeutic assessment of SEED: a new engineered antibody platform designed to generate mono- and bispecific antibodies

The strand-exchange engineered domain (SEED) platform was designed to generate asymmetric and bispecific antibody-like molecules, a capability that expands therapeutic applications of natural antibodies. This new protein engineered platform is based on exchanging structurally related sequences of immunoglobulin within the conserved CH3 domains. Alternating sequences from human IgA and IgG in the SEED CH3 domains generate two asymmetric but complementary domains, designated AG and GA. The SEED design allows efficient generation of AG/GA heterodimers, while disfavoring homodimerization of AG and GA SEED CH3 domains. Using a clinically validated antibody (C225), we tested whether Fab derivatives constructed on the SEED platform retain desirable therapeutic antibody features such as in vitro and in vivo stability, favorable pharmacokinetics, ligand binding and effector functions including antibody-dependent cell-mediated cytotoxicity and complement-dependent cytotoxicity. In addition, we tested SEED with combinations of binder domains (scFv, VHH, Fab). Mono- and bivalent Fab-SEED fusions retain full binding affinity, have excellent biochemical and biophysical stability, and retain desirable antibody-like characteristics conferred by Fc domains. Furthermore, SEED is compatible with different combinations of Fab, scFv and VHH domains. Our assessment shows that the new SEED platform expands therapeutic applications of natural antibodies by generating heterodimeric Fc-analog proteins.