Search results for "efficiency"

Buildings integrated phase change materials: Modelling and validation of a novel tool for the energy performance analysis

2017

In this paper a novel dynamic energy performance simulation model for the Phase Change Materials (PCM) analysis is presented. The model is implemented in a suitable computer code, written in MatLab and called DETECt, for complete building energy analyses. In the presented model, the “effective specific heat” method is implemented. Here, the specific heat of each PCM layer changes as a function of the system phase and temperature in both melting and freezing processes. A model validation is carried out by comparing numerical results vs. measurements obtained at Solar Laboratory of Concordia University (Montreal, Canada). The simulation model allows exploring the potential of PCMs to increase…

A review of DEA models when the internal structure of the decision making units is considered

2005

Classical Data Envelopment Analysis (DEA) models consider each Decision Making Unit (DMU), whose relative efficiency they evaluate, as a "black box", i.e., its internal structure is disregarded. The paper presents a comprehensive framework of the most advanced theoretical findings in DEA when the internal structure of the. DMUs is taken into account, thus giving directions for novel applications of such methodology and introducing it as a powerful toot for complex processes performance evaluation.

<title>Amorphous As-S-Se films for holographic recording</title>

2003

The amorphous As40S15Se45 films as recording media for optical holography were studied. The results on research of transmission and Bragg grating holographic recording and readout conditions are presented. The recording of transmission holographic gratings was performed by He-Ne (0.6328 μm) or Kr+ (0.6764 μm) laser beam, while the readout of the diffraction efficiency was made at Bragg angle using He-Ne (0.6328 and 1.15 μm) or diode (0.805 μm) laser lines. It is shown that self-enhancement of Bragg grating reflectors is possible. The influence of thin film interference conditions on holographic recording parameters is demonstrated.© (2003) COPYRIGHT SPIE--The International Society for Optic…

<title>Bragg and asymmetric-relief reflection gratings in As-S-Se thin films</title>

2005

Bragg and asymmetric-relief gratings and their formation in the amorphous As-S-Se films are discussed. Due to the high refractive index and its photoinduced change, the films are useful in holography. The thickness of the As0.4S0.15Se0.45 and As0.4S0.3Se0.3 films used in the Bragg gratings is optimized. The dependence of the dimaction efficiency of the asymmetric-relief gratings on the conditions of recording, chemical treating, and reading out (polarization and angle) is studied.© (2005) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

A coupled lossy local-mode theory description of a plasmonic tip

2012

International audience; We investigate power propagation in a metal-coated tapered optical fiber. We analyze in detail the conversion from the fiber core guided mode to a surface plasmon polariton (SPP) confined at the tip apex. To this aim, we adapt coupled local-mode theory to include lossy modes. Two distinct regimes are identified. In the case of thin metal coating, a strong coupling regime occurs between a core guided mode and a SPP with good conversion efficiency. In the case of thick metal coating, a very weak coupling occurs. Finally, energy confinement and the role of Joule losses are discussed in the near-infrared and visible ranges. Moreover, the coupled equations derived for loc…

Improving the efficiency of light-emitting diode based on a thiophene polymer containing a cyano group

2007

Abstract We report on the overall improvement of a single layer organic light-emitting diode device based on poly{[3-hethylthiophene]-co-3-[2-( p -cyano-phenoxy)ethyl]thiophene} or namely PTOPhCN. This polymer was recently developed by adding a cyano group as a side-chain substituent of the thiophenic backbone onto the main polymer chain and showed promising results for light-emitting diode devices. Using an improved device layout, bright red electroluminescence was obtained at 4 V and showed a luminance of about 400 cd/m 2 at 8 V with current densities in the order of 6000 A/m 2 .

Firm-sponsored training in regulated labour markets: evidence from Spain

2005

Using data from the 1994 European Community Household Panel Survey, the author examines who receives formal firm-sponsored training in Spain. The author finds that the distribution of firm-sponsored training in the work force is uneven and concentrated among more skilled workers in the upper deciles of the wage distribution. The data show that the likelihood of receiving firm-sponsored training for a low education employee is much lower. Also, the better-educated employees in high wage occupations of the largest establishments have higher probabilities of receiving specific training. Spain has a highly regulated labour market, and the labour market frictions and institutions compress and di…

Turning a new “page”: ways to decrease the number of pages after hours without compromising patient care

2020

Pages to house staff after hours, especially overnight, lead to interrupted sleep and fatigue the next day. Although some pages are urgent, others may not need an immediate response. In this study we aimed to identify unwarranted pages and to establish ways to reduce them.Over 2 months, all pages to the Department of Pediatric Urology at the Hospital for Sick Children in Toronto, Canada, during call hours were documented, including the assessment of the responding physicians of their medical necessity. After analyzing the reasons for inappropriate pages, we took several steps to try to reduce them without impairing patient care. One year later, pages were tracked again to evaluate the effic…

Approximation method for computationally expensive nonconvex multiobjective optimization problems

2012

Minimization of a rectangular patch using genetic algorithms

2002

In recent years, the miniaturization of antennas have become more and more important, especially in connection with subscriber transceivers for cellular systems. Due to the multiple scattering environments and the almost indefinable operating scenario, the crosspolarization characteristics of the antenna are less important, however its physical size is critical. The attempts to reduce the physical size of the antenna made in the past, used classical methods, such as embedding the antenna in a dielectric medium of a high permittivity, adding a resistive element in series with the antenna, etc., but little effort was invested in simply generating other geometries, which by their intrinsic pro…