Enhancement of light extraction in GaN light-emitting diodes (LEDs) employing omnidirectional reflectors (ODRs) is presented. The ODR consists of GaN, ITO nanorod low-refractive-index layer, and an Ag layer. An array ...
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Enhancement of light extraction in GaN light-emitting diodes (LEDs) employing omnidirectional reflectors (ODRs) is presented. The ODR consists of GaN, ITO nanorod low-refractive-index layer, and an Ag layer. An array of ITO nanorods is deposited by oblique-angle deposition using e-beam evaporation. The refractive index of the ITO nanorods is 1.34 at 461 nm, significantly lower that that of dense ITO, which is n = 2.06 at 461 nm. It is experimentally shown that the GaN LED with GaN/ITO nanorods/Ag ODR show much better electrical properties and higher light-extraction efficiency than LEDs with Ag contact. This is attributed to enhanced reflectivity of the ODR by using an ITO low-refractive-index layer with high transparency, high conductivity, and low refractive index.
In this paper, we consider the problem of dynamically regulating the timing of traffic light controllers in busy cities. We use a Stochastic Fluid Model (SFM) to model the dynamics of the queues formed at an intersect...
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In this paper, we consider the problem of dynamically regulating the timing of traffic light controllers in busy cities. We use a Stochastic Fluid Model (SFM) to model the dynamics of the queues formed at an intersection. Based on this model, we derive gradients of the queue lengths with respect to the green/red light lengths within a signal cycle. We report preliminary numerical results comparing the performance of the estimates with finite-difference and smoothed perturbation analysis estimates. Then all estimators are used to optimize the traffic system via Stochastic Approximation.
作者：
De Brito, Halisson MatosStrauch, JuliaDe Souza, Jano MoreiraOsthoff, CarlaCOPPE/UFRJ
Systems Engineering and Computer Science Program Federal University of Rio de Janeiro PO Box 68511 ZIP Code: 21945-970 Rio de Janeiro RJ Brazil ENCE /IBGE
National School of Statistical Sciences 106 S. 401 ZIP Code: 20231-050 R. André Cavalcanti Rio de Janeiro RJ Brazil LNCC
National Laboratory for Scientific Computing Av. Getulio 333 Quitandinha Vargas Petrópolis RJ Brazil IM/UFRJ
Institute of Mathematics Federal University of Rio de Janeiro PO Box 68511 ZIP Code: 21945-970 Rio de Janeiro RJ Brazil
This paper presents MODENA, an architecture for scientific models management using Computational Grid platform. This architecture is comprised of two systems: ModManager and ModRunner. ModManager deals with knowledge ...
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This paper presents MODENA, an architecture for scientific models management using Computational Grid platform. This architecture is comprised of two systems: ModManager and ModRunner. ModManager deals with knowledge management about scientific models, acting as a scientific models library allowing for cataloguing, searching, reutilization and generation of new models. To achieve this, a metamodel is proposed to classify models, in order to support the organization, searching and retrieving of models. ModRunner manages the execution of models in a Grid environment allowing for model composition to generate a scientific Grid Workflow to be executed by distributed services offered by Grid Services. An initial prototype of ModManager is presented.
This work focuses the problem of further development of the approach to the fast cipher design, based on data-dependent (DD) permutations (DDP). A new class of the DDP-like operations is described. New DD operations (...
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This work focuses the problem of further development of the approach to the fast cipher design, based on data-dependent (DD) permutations (DDP). A new class of the DDP-like operations is described. New DD operations (DDO) are constructed replacing the switching element in the DDP boxes by different controlled elements (CE) having the same size. Full classification of CE with two non-linear outputs is presented. Two subclasses of nonlinear CE, with the best differential characteristics are recommended for the use in the non-linear DDO-boxes synthesis. The non-linear CE boxes are implemented in FPGA modules using the same hardware resources as switching elements. It is shown that the use of the nonlinear DDO, instead of DDP allows one to reduce the number of rounds. With this technique higher Performance/Cost ratio is achieved, while designing fast hardware suitable ciphers.
This work focuses the problem of increasing the performance of the ciphers based on data-dependent (DD) operations (DDO) for VLSI implementations. New minimum size primitives are proposed to design DDOs. Using advance...
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This work focuses the problem of increasing the performance of the ciphers based on data-dependent (DD) operations (DDO) for VLSI implementations. New minimum size primitives are proposed to design DDOs. Using advanced DDOs instead of DD permutations (DDP) in the DDP-based iterative ciphers Cobra-H64 and Cobra H128 the number of rounds has been significantly reduced yielding enhancement of the "performance per cost" value. To obtain further enhancement of this parameter a new crypto-scheme based on the advanced DDOs is proposed. The FPGA implementation of the proposed crypto-scheme achieves higher throughput value and minimizes the allocated resources than the conventional designs.
Synapses are a critical element of biologically-realistic, spike-based neural computation, serving the role of communication, computation, and modification. Many different circuit implementations of synapse function e...
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ISBN:
(纸本)0262201526
Synapses are a critical element of biologically-realistic, spike-based neural computation, serving the role of communication, computation, and modification. Many different circuit implementations of synapse function exist with different computational goals in mind. In this paper we describe a new CMOS synapse design that separately controls quiescent leak current, synaptic gain, and time-constant of decay. This circuit implements part of a commonly-used kinetic model of synaptic conductance. We show a theoretical analysis and experimental data for prototypes fabricated in a commercially-available 1.5μm CMOS process.
A novel microwave nondestructive testing technique is presented for breast cancer detection. A method utilizing the reflection coefficient at the aperture of a waveguide sensor radiating into a breast is described res...
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A novel microwave nondestructive testing technique is presented for breast cancer detection. A method utilizing the reflection coefficient at the aperture of a waveguide sensor radiating into a breast is described resulting in theoretical microwave images that clearly indicate the presence of a tumor. These images demonstrate the feasibility of detecting breast tumors using this approach
Integrated, low-power, low-noise CMOS neural amplifiers have recently grown in importance as large microelectrode arrays have begun to be practical. With an eye to a future where thousands of signals must be transmitt...
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Integrated, low-power, low-noise CMOS neural amplifiers have recently grown in importance as large microelectrode arrays have begun to be practical. With an eye to a future where thousands of signals must be transmitted over a limited bandwidth link or be processed in situ, we are developing low-power neural amplifiers with integrated pre-filtering and measurements of the spike signal to facilitate spike-sorting and data reduction prior to transmission to a data-acquisition system. We have fabricated a prototype circuit in a commercially-available 1.5 /spl mu/m, 2-metal, 2-poly CMOS process that occupies approximately 91,000 square /spl mu/m. We report circuit characteristics for a 1.5 V power supply, suitable for single cell battery operation. In one specific configuration, the circuit bandpass filters the incoming signal from 22 Hz to 6.7 kHz while providing a gain of 42.5 dB. With an amplifier power consumption of 0.8 /spl mu/W, the rms input-referred noise is 20.6 /spl mu/V.
The semantic Web technology and the Web services description language extensibility may be combined to describe services in an unambiguous and machine interpretable way, automating Web services discovery, selection an...
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The semantic Web technology and the Web services description language extensibility may be combined to describe services in an unambiguous and machine interpretable way, automating Web services discovery, selection and invocation. In this paper, we present an algorithm and a prototype for the automatic composition of Web services that implement workflows described in a high level language. Our approach has many advantages comparing to the manual creation of a simple program composition, such as smaller implementation time and cost, reliability with the generation of contingency plans, greater capacity to evolve with the dynamic service discovery, and faster execution time with the use of heuristics. We use the OWLS ontology to semantically describe Web services metadata and indexes to help selecting them. The proposed algorithm considers that equivalent services may have different interfaces and also respects preferences of the users.
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