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Conventional Structure (conventional + structure)
Selected AbstractsRecent Progress in Polymer Solar Cells: Manipulation of Polymer:Fullerene Morphology and the Formation of Efficient Inverted Polymer Solar CellsADVANCED MATERIALS, Issue 14-15 2009Li-Min Chen Abstract Polymer morphology has proven to be extremely important in determining the optoelectronic properties in polymer-based devices. The understanding and manipulation of polymer morphology has been the focus of electronic and optoelectronic polymer-device research. In this article, recent advances in the understanding and controlling of polymer morphology are reviewed with respect to the solvent selection and various annealing processes. We also review the mixed-solvent effects on the dynamics of film evolution in selected polymer-blend systems, which facilitate the formation of optimal percolation paths and therefore provide a simple approach to improve photovoltaic performance. Recently, the occurrence of vertical phase separation has been found in some polymer:fullerene bulk heterojunctions.1,3 The origin and applications of this inhomogeneous distribution of the polymer donor and fullerene acceptor are addressed. The current status and device physics of the inverted structure solar cells is also reviewed, including the advantage of utilizing the spontaneous vertical phase separation, which provides a promising alternative to the conventional structure for obtaining higher device performance. [source] Compact microstrip low-pass filter using complementary split ring resonators with ultra-wide stopband and high selectivityMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 2 2010Hui-Yong Zeng Abstract The transmission characteristic of the microstrip with complementary split ring resonator (CSRR) is researched. Compared with the conventional structure, this filter can achieve a wider bandgap by shifting the gap of CSRR from the side of the microstrip to the underside. And then, a lower transmission zero can be realized by loading a pair of narrow slots in the gap of the ring. The equivalent circuit model of the structure is provided. By cascading CSRR cells with different transmission zeros, a ultra-wide bandgap low-pass filter (LPF), which has a cutoff frequency at 4.3 GHz is designed. The designed LPF has a high performance with an insertion loss lower than 0.3 dB in pass band, a high out-band suppression more than 20 dB (4.55,25 GHz), and a very sharp transition band about 0.25 GHz (4.3,4.55 GHz). © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 430,433, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24942 [source] A 2.4/5.7-GHz dual-band low-power CMOS RF receiver with embedded band-select switchesMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 3 2009D.-R. Huang Abstract This article presents a 2.4-/5.7-GHz dual-band low-power direct-conversion CMOS RF receiver for the 802.11a/b/g WLAN applications. The RF receiver includes a low noise amplifier (LNA) with dual input stages and dual switches for each of 2.4/5.7-GHz applications. This design can substitute the use of two LNAs in conventional structure and eliminate the use of the costly external band-select switches. It also alleviates the difficulty of single matching for multiple frequency bands. The RF receiver also includes a Gilbert-cell-based broadband mixer which is designed to be both low power consumption and relatively high conversion gain. Fabricated in 0.18-,m CMOS technology, the RF receiver exhibits a conversion gain of 25.8/20.6 dB, DSB noise figure of 4.4/5.6 dB, and input IP3 of ,18/,12.5 dBm at 2.4/5.7 GHz frequency band, respectively. The measured EVM for IEEE 802.11a/b/g is 1.2/1.6/1.1% at data rate of 11/54/54 Mbps. The power consumption under 1.8 V supply is 10.6 mW for the 2.4 GHz mode, and 17.2 mW for the 5.7 mode. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 593,597, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24120 [source] Brightness enhancement of ITO/GaN LEDs by self-aligned micro-net structuresPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 7 2005Kow-Ming Chang Abstract Arrays of square and hexagonal holes of various dimensions were patterned on indium-tin-oxide (ITO)/GaN light-emitting diodes (LEDs) using the self-aligned method to increase the light extraction area and shorten the optical paths. The hole region was etched to give the sidewall of the active layer a sloped profile, and it was passivated by SiOxNy films to extract more light. The self-aligned micro-net LED is at least 10% brighter than the conventional structure in the normal direction without loss of operating voltage or leakage current. The ratio of luminescence to total output power is increased by 25% at a current density of 100 A/cm2. Moreover, varying the hole dimensions and the designed density increased the peak external quantum efficiency by 5% at a current of 3 mA. The greater axial luminescence and the higher external quantum efficiency make LEDs self-aligned micro-net structures quite useful in surface-mounting and low-power-consuming devices, such as cellular phones. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Sensitivity of seismically isolated structuresEARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 8 2009Ioannis Politopoulos Abstract In this paper we study the sensitivity of seismically isolated structures to a small variability of the earthquake excitation and of some structural properties with respect to the probability of failure and floor spectra. In particular, the influence of the nonlinear behaviour of the isolated superstructure on the vulnerability and on the floor spectra is investigated by means of a series of Monte Carlo simulations of simple two degrees-of-freedom systems. Several types of passive and active isolation systems are examined and three different idealized nonlinear constitutive laws are considered for the superstructure. It is found that, in general, the probability of failure does not depend on the specific cyclic behaviour of the assumed constitutive law and general trends regarding the impact of different isolation devices on vulnerability are established. As for the floor spectra, the influence of moderate nonlinear behaviour of isolated superstructures, with the exception of the case of a non-dissipative elastic nonlinear law, is negligible, contrary to the case of conventional structures. Copyright © 2008 John Wiley & Sons, Ltd. [source] Shaking table tests on reinforced concrete frames without and with passive control systemsEARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 14 2005Mauro Dolce Abstract An extensive experimental program of shaking table tests on reduced-scale structural models was carried out within the activities of the MANSIDE project, for the development of new seismic isolation and energy dissipation devices based on shape memory alloys (SMAs). The aim of the experimental program was to compare the behaviour of structures endowed with innovative SMA-based devices to the behaviour of conventional structures and of structures endowed with currently used passive control systems. This paper presents a comprehensive overview of the main results of the shaking table tests carried out on the models with and without special braces. Two different types of energy dissipating and re-centring braces have been considered to enhance the seismic performances of the tested model. They are based on the hysteretic properties of steel elements and on the superelastic properties of SMAs, respectively. The addition of passive control braces in the reinforced concrete frame resulted in significant benefits on the overall seismic behaviour. The seismic intensity producing structural collapse was considerably raised, interstorey drifts and shear forces in columns were drastically reduced. Copyright © 2005 John Wiley & Sons, Ltd. 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