Solution‐Processable,High‐Performance Flexible Electroluminescent Devices Based on High‐k Nanodielectrics

Flexible alternating‐current electroluminescent (ACEL) devices have attracted considerable attention for their ability to produce uniform light emission under bent conditions and have enormous potential for applications in back lighting panels, decorative lighting in automobiles, and panel displays. Nevertheless, flexible ACEL devices generally require a high operating bias, which precludes their implementation in low power devices. Herein, solution‐processed La‐doped barium titanate (BTO:La) nanocuboids (≈150 nm) are presented as high dielectric constant (high‐k) nanodielectrics, which can enhance the dielectric constant of an ACEL device from 2.6 to 21 (at 1 kHz), enabling the fabrication of high‐performance flexible ACEL devices with a lower operating voltage as well as higher brightness (≈57.54 cd m^?2 at 240 V, 1 kHz) than devices using undoped BTO nanodielectrics (≈14.3 cd m^?2 at 240 V, 1 kHz). Furthermore, a uniform brightness across the whole panel surface of the flexible ACEL devices and excellent device reliability are achieved via the use of uniform networks of crossaligned silver nanowires as highly conductive and flexible electrodes. The results offer experimental validation of high‐brightness flexible ACELs using solution‐processed BTO:La nanodielectrics, which constitutes an important milestone toward the implementation of high‐k nanodielectrics in flexible displays.     

A Multiscale-Porous Anion Exchange Membrane for Convenient and Scalable Electrokinetic Concentration of Cationic Species

A device able to electrokinetically concentrate cationic samples has many potential medical and industrial applications, but until now has remained undeveloped due to the lack of a commercial anion-permselective material leading to a prohibitively complex fabrication procedure. Herein, a novel multiscale-porous anion exchange membrane (MP-AEM) that enables the convenient and scalable electrokinetic concentration of cationic species is proposed. A mechanically enhanced multiscale-porous structure with a solid framework is realized by adopting polyester resin as an additive to overcome the intrinsic limitations of the AEM material. The scalable MP-AEM-embedded electrokinetic concentrator is devised based on the peculiar properties of the MP-AEM that for allow both ion and fluid transport. With the MP-AEM, the concentrator is fabricated in a highly streamlined manner consisting only of a simple insertion and assembly. The concentration performance of the MP-AEM-embedded electrokinetic concentrator is demonstrated with a positively charged fluorescent dye and a fluorescein-labeled protein, and the results show enrichment factors of 250 and 500, respectively. The MP-AEM makes cationic electrokinetic concentration more accessible and scalable, thereby enabling further progress in a wide range of fields.     

Self‐adapting protocol tuning for multi‐hop wireless networks using Q‐learning

Today's network control systems have very limited ability to adapt to changing network conditions. The addition of reinforcement learning‐based network management agents can improve quality of service by reconfiguring the network layer protocol parameters in response to observed network performance conditions. This paper presents a closed‐loop approach to tuning the layer three protocol based upon current and previous network state observations, specifically the Hello Interval and Active Route Timeout parameters of the AODV routing protocol (AODV‐Q). Simulation results demonstrate that the self‐configuration method proposed here demonstrably improves the performance of the original Ad‐Hoc On‐Demand Distance Vector (AODV) protocol, reducing protocol overhead by 43% and end‐to‐end delay 29% while increasing the packet delivery ratio by up to 11%. Copyright © 2012 John Wiley & Sons, Ltd.     

Evaluation of relationship between biogas production and microbial communities in anaerobic co-digestion

Anaerobic co-digestion (ACD) has been used to treat various organic wastes because nutrient balance in the feed can be improved by mixing different organics. Until now, the correlation between characteristics of feedstocks and biogas production by ACD has been studied mainly in terms of biochemical methane potential. It has been rarely tried to understand the co-digestion process in terms of microbial community development. This study aimed to evaluate the performance of batch anaerobic digestion (AD) reactors fed with activated sludge (AS), swine slurry (SS) and food waste (FW) individually or in a mixture of the three wastes (FW: SS : AS=1 : 3 : 2). The AD reactors fed with the mixture showed better performance than those fed with a single substrate. Microbial communities of the batch AD reactors fed with a single substrate or the mixture were analyzed and the result was related to the performance of the AD reactors.     

Organic/Inorganic Hybrid Composite Films from Polyimide and Organosilica: Effect of the Type of Organosilica Precursors

We report the influence of the type of organosilica precursors on the growth of organosilica domains and the interfacial interaction between polyimide (PI) and organosilica in PI/organosilica hybrid composite films. The organosilica precursors used are tetraethoxysilane (TEOS), triethoxy(ethyl)silane (TEES), and 1,2-bis(triethoxysilyl)ethane (BTSE). The hybrid composite films were prepared by thermal imization of the precursor films that were made via sol-gel process of the mixture of poly(4,4’-oxydianiline benzenetetracarboxamic acid) (PMDA-ODA PAA) and organosilica precursors. The hybrid composite films were characterized using Fourier transform infrared (FT-IR) spectra, ²⁹Si cross polarization (CP) MAS-NMR spectra, field emission-scanning electron microscopy (FE-SEM), UV-visible spectra, small angle x-ray scattering (SAXS), dynamic mechanical analysis (DMA), and thermogravimetric analysis (TGA). The results showed that the TEES precursor was more pronounced in improving the interaction of corresponding organosilica with PI than other precursors.     

Optimum MVF Estimation‐Based Two‐Band Excitation for HMM‐Based Speech Synthesis

The optimum maximum voiced frequency (MVF) estimation‐based two‐band excitation for hidden Markov model‐based speech synthesis is presented. An analysis‐by‐synthesis scheme is adopted for the MVF estimation which leads to the minimum spectral distortion of synthesized speech. Experimental results show that the proposed method significantly improves synthetic speech quality.     

Simulation of shear fracture in sheet metal forming of thick plates under triaxial stress states

Journal of Mechanical Science and Technology - In industrial sheet forming of high strength steel sheets, shear fracture has been reported to occur in narrow die shoulders where the sheet is...     

A Hierarchical Nanoparticle‐in‐Micropore Architecture for Enhanced Mechanosensitivity and Stretchability in Mechanochromic Electronic Skins

Biological tissues are multiresponsive and functional, and similar properties might be possible in synthetic systems by merging responsive polymers with hierarchical soft architectures. For example, mechanochromic polymers have applications in force‐responsive colorimetric sensors and soft robotics, but their integration into sensitive, multifunctional devices remains challenging. Herein, a hierarchical nanoparticle‐in‐micropore (NP‐MP) architecture in porous mechanochromic polymers, which enhances the mechanosensitivity and stretchability of mechanochromic electronic skins (e‐skins), is reported. The hierarchical NP‐MP structure results in stress‐concentration‐induced mechanochemical activation of mechanophores, significantly improving the mechanochromic sensitivity to both tensile strain and normal force (critical tensile strain: 50% and normal force: 1 N). Furthermore, the porous mechanochromic composites exhibit a reversible mechanochromism under a strain of 250%. This architecture enables a dual‐mode mechanochromic e‐skin for detecting static/dynamic forces via mechanochromism and triboelectricity. The hierarchical NP‐MP architecture provides a general platform to develop mechanochromic composites with high sensitivity and stretchability.     

A survey of security issue in multi-agent systems

Multi-agent systems have attracted the attention of researchers because of agents’ automatic, pro-active, and dynamic problem solving behaviors. Consequently, there has been a rapid development in agent technology which has enabled us to provide or receive useful and convenient services in a variety of areas such as banking, transportation, e-business, and healthcare. In many of these services, it is, however, necessary that security is guaranteed. Unless we guarantee the security services based on agent-based systems, these services will face significant deployment problems. In this paper, we survey existing work related to security in multi-agent systems, especially focused on access control and trust/reputation, and then present our analyses. We also present existing problems and discuss future research challenges.