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971.
《Journal of the European Ceramic Society》2014,34(12):3111-3117
Highly electrically conductive ceramic material based on aluminosilicate/graphene nanocomposite has been prepared by high pressure (400 MPa) compaction of montmorillonite intercalated with polyaniline followed with the high temperature (1400 °C) treatment in argon atmosphere. Tablets pressed from polyaniline/montmorillonite intercalate exhibits strong texture due to the disk-shaped montmorillonite particles and, consequently, the high anisotropy in conductivity. The high temperature induced phase transformation of montmorillonite into cristobalite and mullite preserved the aluminosilicate layered structure and created good conditions for formation of graphene sheets from polyaniline layers intercalated in montmorillonite. Therefore, the texture and anisotropy in conductivity remain preserved in resulting aluminosilicate/graphene tablets, while the in-plane conductivity in aluminosilicate/graphene tablets is 23,000× higher than the conductivity of uncalcined polyaniline/montmorillonite tablets. Simple fabrication method of aluminosilicate/graphene tablets is very promising for the manufacturing of the electrically conductive and tough ceramic material, which can be exposed to corrosive environment as well as to high temperatures. 相似文献
972.
In this paper, we present the optimization of single-walled carbon nanotubes (SWCNTs) by acid-treatment, solution ultrasonication time and dispersion in photoactive layer for efficient organic solar cells. After non-covalently adhering with poly(3-hexylthiophene) (P3HT), pre-functionalized SWCNTs were blended into the composites of P3HT and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) as photoactive layer, and a maximum power conversion efficiency (PCE) of 3.02% with a short-circuit current density of 11.46 mA/cm2 was obtained from photovoltaic cell indium-tin oxide (ITO)/poly(ethylene-dioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS)/P3HT:PCBM:SWCNTs/Al with an optimum 0.3 wt% SWCNTs in P3HT:PCBM:SWCNTs nanocomposite, the PCE can be enhanced by more than 10% as compared to the control device ITO/PEDOT:PSS/P3HT:PCBM/Al. The performance improvement by incorporating with functionalized SWCNTs is mainly attributed to the extension of excitons dissociation area and fastening charge carriers transfer across the active layer. 相似文献
973.
《Journal of the European Ceramic Society》2014,34(3):687-694
The influence of 30 GHz microwave sintering compared to conventional sintering has been investigated on polycrystalline Ba0.6Sr0.4TiO3 (BST60) thick films with respect to an application as tunable dielectrics. The BST thick films were prepared as metal–insulator–metal (MIM) capacitors on alumina substrates. The average grain size (440 nm) and the porosity (approx. 30%) of the sintered films are only little affected by the sintering method. However, permittivity, dielectric loss and tunability have been influenced substantially. The dielectric improvement by microwave sintering is interpreted in terms of an increased crystal quality (ξS) and/or a decrease of defect concentrations. It is assumed that microwave sintering preferably heats up parts of the film where an increased defect density exists and therefore causes a selective heating process. This may heal up charged defects, inhomogeneities, and structural defects. 相似文献
974.
《Journal of the European Ceramic Society》2014,34(15):3627-3633
Aluminum nitride (AlN) ceramics with the concurrent addition of CaZrO3 and Y2O3 were sintered at 1450-1700 °C. The degree of densification, microstructure, flexural strength, and thermal conductivity of the resulting ceramics were evaluated with respect to their composition and sintering temperature. Specimens prepared using both additives could be sintered to almost full density at relatively low temperature (3 h at 1550 °C under nitrogen at ambient pressure); grain growth was suppressed by grain-boundary pinning, and high flexural strength over 630 MPa could be obtained. With two-step sintering process, the morphology of second phase was changed from interconnected structure to isolated structure; this two-step process limited grain growth and increased thermal conductivity. The highest thermal conductivity (156 Wm−1 K−1) was achieved by two-step sintering, and the ceramic showed moderate flexural strength (560 MPa). 相似文献
975.
Ad hoc sharing of resources by offering remote services through an appropriate infrastructure enables new applications for mobile devices. However, the willingness of device owners to contribute resources to such applications remains low as long as they cannot control the amount of energy spent in sharing. In this paper, we present a framework for energy-aware resource sharing among mobile devices of various kinds that comprises (1) energy-aware strategies for selecting remote service providers and (2) a generic energy estimator for forecasting and accounting the energy consumption of a remote service call. To illustrate the benefit of (1), we show by simulation that the battery lifetime of devices running the framework can be extended up to 40% by service selection strategies that take into account the energy cost of a requested service compared to energy-unaware (random) service selection. For providing the energy-related input for service selection, we present (2) a generic estimator that can be customized easily for different hardware-platforms by solving a linear equation system with coefficients derived from benchmark measurements. We present a prototype-based case study for three different platforms, the Nokia N810, the HTC Touch Cruise and the Samsung Galaxy S showing that for all of them the estimation error is below 10% for 90% of the service calls. Furthermore, measurements conducted with a prototype implementation of the resource sharing framework show that battery lifetime can in fact be extended by energy-aware service selection strategies. 相似文献
976.
977.
《Expert systems with applications》2014,41(13):5702-5709
Context-aware applications, which consist of a sensor system, a reasoning system and service artifacts such as mobile devices, kiosks and robots, require data from the sensors to be queried on a continuous basis. The smaller the sensing interval and the greater the amount of service time, the more accurate the service, but the more energy is consumed. Thus, use of context-aware applications always involves a trade-off. In this paper, we propose an automatic method of optimizing the level of personalization involving the sensing cycle and service time of a personalized application. The method proposes a quadratic form of total cost curve which demonstrated that the minimum identified value is always the global optimum. This eliminates the necessity of an exhaustive search for the minimum value for all levels of personalization. 相似文献
978.
User profiles play an important role in information retrieval system. In this paper, we propose a novel method for the acquisition of ontology-based user profiles. In the method, the ontology-based user profiles can maintain the representations of personal interest. In addition, user ontologies can be automatically constructed. The method can make user profiles strong expressive and less manually interfered. 相似文献
979.
Jie Yuan Ning Song Nabil Farhat Jan Van der Spiegel 《Analog Integrated Circuits and Signal Processing》2009,59(3):287-300
The clustering of spatio-temporal patterns are essential for many applications. Established from the biological analogy of
the cortex, the parametrically coupled logistic map network (PCLMN) provides a viable solution to the clustering problem.
To engineer for a single-chip spatio-temporal pattern clustering system, the highly modular PCLMN is designed in analog circuit.
In this paper, the 0.6 μm 5 V CMOS design of the processing element is presented. The analog design employs self-calibration
techniques to improve the accuracy and robustness of the nonlinear circuits. A fabricated element covers a die area of 0.55
mm2, and consumes 240 mW power at 5 V supply. After calibration, simulation and testing results show that the element fulfills
the system-level requirement of the Cort-X model for driving signals up to 1 MHz. 相似文献
980.
A new method for combining visual and semantic features in image retrieval is presented. A fuzzy k-NN classifier assigns initial semantic labels to database images. These labels are gradually modified by relevance feedbacks from the users. Experimental results on a database of 1000 images from 10 semantic groups are reported. 相似文献