Accurate FDTD Dispersive Modeling for Concrete Materials

This work presents an accurate finite‐difference time‐domain (FDTD) dispersive modeling of concrete materials with different water/cement ratios in 50 MHz to 1 GHz. A quadratic complex rational function (QCRF) is employed for dispersive modeling of the relative permittivity of concrete materials. To improve the curve fitting of the QCRF model, the Newton iterative method is applied to determine a weighting factor. Numerical examples validate the accuracy of the proposed dispersive FDTD modeling.     

A printed OTFT-backplane for AMOLED display

An AMOLED panel driven by an OTFT-backplane is an attractive display because OTFTs and OLEDs use organic materials with unique characteristics such as low temperature and solution processing ability, and thus are able to implement the key features of future displays. In this study we applied some printing technologies to fabricate an OTFT-backplane for AMOLEDs. Screen printing combined with photolithography with Ag ink was used for the gate electrodes and scan bus lines and contact pads. Ag metal lines with a width of 20 μm and thickness of 60 nm and resistivity of 3.0 × 10^?5 Ω cm were achieved. Inkjet printing was applied to deposit TIPS-pentacene as an organic semiconductor. The OTFT-backplane using the Ag gate electrodes and TIPS-pentacene exhibited uniform performance over 17,500 pixels on a 7 in. panel. The mobility was 0.31 ± 0.05 cm²/V s with a deviation of 17%. The AMOLED panel successfully demonstrated its ability to display patterns.     

Complementary Absorbing Star‐Shaped Small Molecules for the Preparation of Ternary Cascade Energy Structures in Organic Photovoltaic Cells

Two anthracene‐based star‐shaped conjugated small molecules, 5′,5″‐(9,10‐bis((4‐hexylphenyl)ethynyl)anthracene‐2,6‐diyl)bis(5‐hexyl‐2,2′‐bithiophene), HBantHBT, and 5′,5″‐(9,10‐bis(phenylethynyl)anthracene‐2,6‐diyl)bis(5‐hexyl‐2,2′‐bithiophene), BantHBT, are used as electron‐cascade donor materials by incorporating them into organic photovoltaic cells prepared using a poly((5,5‐E‐alpha‐((2‐thienyl)methylene)‐2‐thiopheneacetonitrile)‐alt‐2,6‐[(1,5‐didecyloxy)naphthalene])) (PBTADN):[6,6]‐phenyl‐C71‐butyric acid methyl ester (PC₇₁BM) blend. The small molecules penetrate the PBTADN:PC₇₁BM blend layer to yield complementary absorption spectra through appropriate energy level alignment and optimal domain sizes for charge carrier transfer. A high short‐circuit current (J_SC) and fill factor (FF) are obtained using solar cells prepared with the ternary blend. The highest photovoltaic performance of the PBTADN: BantHBT :PC₇₁BM blend solar cells is characterized by a J_SC of 11.0 mA cm^?2, an open circuit voltage (V_OC) of 0.91 V, a FF of 56.4%, and a power conversion efficiency (PCE) of 5.6% under AM1.5G illumination (with a high intensity of 100 mW^?2). The effects of the small molecules on the ternary blend are investigated by comparison with the traditional poly(3‐hexylthiophene) (P3HT):[6,6]‐phenyl‐C61‐butyric acid methyl ester (PC₆₁BM) system.     

Virus‐Tethered Magnetic Gold Microspheres with Biomimetic Architectures for Enhanced Immunoassays

In immunoassays, non‐specific bindings to biosensing surfaces can be effectively prevented by formation of biocompatible and hydrophilic self‐assembled monolayer (SAM) on the surfaces. A thin gold (Au) layer on magnetic microspheres, 15 μm in diameter, enables facile SAM formation and thereby accepts second layer of filamentous virus scaffolds for the immobilization of functional proteins. The merger of the virus and SAM‐Au protected microspheres not only provides exceptionlly dense antibody loading, but also resembles biological cellular structures that enhance ligand‐receptor interactions. Site‐specific biotinylation of filamenous viruses allows formation of free‐standing virus threads (>1.0 × 10¹⁰) on streptavidin‐modified SAM‐Au microspheres. The augmented yield of antibody loading, due to the increased surface to volume ratio, on virus‐modified Au microspheres is confirmed by measuring fluorescence intensities. The bead‐based immunoassays for the detection of cardiac marker proteins exhibit increased sensitivity of virus‐Au microspheres, as low as 20 pg mL^?1 of cardiac troponin I in serum, and extremely low non‐specific adsorption when compared with bare polymer beads. This increased sensitivity due to filamentous morphology and SAM‐Au layer demonstrates the feasibility of merging viruses with non‐biological materials to yield biomimetic tools for the enhanced bead‐based immunoassays.     

A lightweight,self‐adaptive lock gate designation scheme for data collection in long‐thin wireless sensor networks

Constrained by the physical environments, the long‐thin topology has recently been promoted for many practical deployments of wireless sensor networks (WSNs). In general, a long‐thin topology is composed of a number of long branches of sensor nodes, where along a branch each sensor node has only one potential parent node toward the sink node. Although data aggregation may alleviate excessive packet contention, the maximum payload size of a packet and the dynamically changing traffic loads may severely affect the amount of sensor readings that may be collected along a long branch of sensor nodes. In addition, many practical applications of long‐thin WSNs demand the exact sensor readings at each location along the deployment areas for monitoring and analysis purposes, so sensor readings may not be aggregated when they are collected. This paper proposes a lightweight, self‐adaptive scheme that designates multiple collection nodes, termed lock gates, along a long‐thin network to collect sensor readings sent from their respective upstream sensor nodes. The self‐adaptive lock gate designation scheme balances between the responsiveness and the congestion of data collection while mitigating the funneling effect. The scheme also dynamically adapts the designation of lock gates to accommodate the time‐varying sensor reading generation rates of different sensor nodes. A testbed of 100 Jennic sensor nodes is developed to demonstrate the effectiveness of the proposed lock gate designation scheme. Copyright © 2011 John Wiley & Sons, Ltd.     

A complete resistance extraction methodology and circuit models for typical TSV structures

Through-silicon via (TSV) is one of the key technologies on three-dimensional integration packaging. In this article, an experimental methodology with circuit models was proposed for electrical characteristic tests on typical TSV structures. To this end, self-developed test patterns such as the via chains, the snake interconnections and the Kelvin structures with different dimensions were designed and manufactured. Suitable electrical measurement methodologies were next employed to characterise the element behaviours of the patterns. Based on the experimental data, electrical circuit models for the TSV structures were introduced and the parameters of the model were exacted. The validity and accuracy of the electrical model were finally verified and the TSV characteristic measurements can be performed through a simpler process.     

Power optimization of multi-level logic circuits utilizing circuit symmetries

The property of circuit symmetry has long been applied to the problem of minimizing the area and timing of multi-level logic circuits. In this paper, we focus on another important design objective, power optimization, utilizing circuit symmetries. First, we analyse and establish the relationship between several types of circuit symmetry and their applicability to reducing power consumption of the circuit, proposing a set of re-synthesis techniques utilizing the symmetries. We derive an algorithm for detecting the symmetries (among the internal signals as well as the primary inputs) on a given circuit implementation. We then propose an effective transformation algorithm to minimize power consumption using the symmetry information detected from the circuit. Unlike many other approaches, our transformation algorithm guarantees monotonic improvement in terms of switching activities, which is practically useful in that user can check the intermediate re-synthesized designs in terms of the degree of changes of power, area, timing, and the circuit structure. We have carried out experiments on MCNC benchmark circuits to demonstrate the effectiveness of our algorithm. On average we reduced the power consumption of circuits by 12% with relatively little increase of area and timing.     

High output impedance current-mode first-order allpass networks with four grounded components and two CCIIs

Eight current-mode first-order allpass networks using second-generation current conveyors (CCII) are presented. Each of the proposed circuits employs two CCIIs, two grounded capacitors and two grounded resistors. The networks offer high output impedances. Experimental results are also included.     

Home Health Gateway Based Healthcare Services Through U-Health Platform

The Ubiquitous Health, or u-Health, service is an IT health care service using the ubiquitous computing environment. U-Health provides customized medical services. As it is a service that has developed from the current hospital visiting medical system, the u-Health service provides a patient with healthcare anywhere and anytime. In this paper, we propose a home health gateway based healthcare services through the u-Health platform. Using home health gateway, u-Health can provide health monitoring, diet, and exercise services using the healthcare decision support module in the ubiquitous environment. This approach would offer specialized services using an external content provider of DB. In addition, a doctor can provide advice to patients using the monitoring service. The proposed u-Health platform provides effective services using home health gateway in ubiquitous environments to customers, which will improve the health of chronic patients.     

Transmission Power Control Aware Routing in Cognitive Radio Ad Hoc Networks

Abstract—Cognitive radio technology has drawn much attention since it is a promising candidate to efficiently utilize the scarce radio resources. However, cognitive radio introduces new challenges in the protocol stacks in wireless networks. This paper proposes a routing protocol for Cognitive Radio Ad Hoc Networks (CRAHNs), called Transmission Power Control aware AODV (TPC-AODV). TPC-AODV is based on Ad hoc On Demand Distance Vector (AODV) routing protocol. The main objectives of TPC-AODV are to avoid interruption of primary users’ communication and to support basic Quality of Service for secondary users. TPC-AODV takes inputs from both secondary users’ application requirements and the channel condition after spectrum sensing. These inputs enable secondary users’ communication with specific transmission power on the selected channel. Our simulation results show that TPC-AODV improves network performance in terms of throughput and delay compared to AODV in CRAHNs.