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1.
We demonstrated efficient white electrophosphorescence with a heavily doped phosphorescent blue emitter and a triplet exciton blocking layer (TEBL) inserted between the hole transporting layer (HTL) and the emitting layer (EML). We fabricated white organic light-emitting diodes (WOLEDs) (devices A, B, C, and D) using a phosphorescent red emitter; bis(2-phenylquinolinato)-acetylacetonate iridium III (Ir(pq)2acac) doped in the host material; N,N′-dicarbazolyl-3,5-benzene (mCP) as the red EML and the phosphorescent blue emitter; bis(3,5-Difluoro-2-(2-pyridyl)phenyl-(2-carboxypyridyl) iridium III (FIrpic) doped in the host material; p-bis(triphenylsilyly)benzene (UGH2) as the blue EML. The properties of device B, which demonstrate a maximum luminous efficiency and external quantum efficiency of 26.83 cd/A and 14.0%, respectively, were found to be superior to the other WOLED devices. It also showed white emission with CIEx,y coordinates of (x = 0.35, y = 0.35) at 8 V. Device D, which has a layer of P-type 4,4′,4″-tri(N-carbazolyl)triphenylamine (TCTA) material between the HTL and TEBL, was compared with device A to determine the 430 nm emission peak. 相似文献
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The cycle time-throughput curve is one of the most important analytical tools used to assess operating policies in manufacturing systems. Unfortunately, the generation of this curve is complicated and time consuming when generation is based upon extensive simulation analysis. This paper presents a simulation-based, fixed sample size strategy for generating a cycle time-throughput curve with minimal mean square error that mitigates the typical problems associated with a simulation-based cycle time-throughput curve. The strategy comprises two components, the sampling method and sampling weights. A queuing network of five workstations in series is used for validation of the approach. Results indicate that the sampling method using antithetic variates is effective in reducing the variance as well as bias of a cycle time-throughput curve. Furthermore, this method is robust to the sample size. Given a sufficiently large sample, the combination of common random numbers and antithetic variates is preferred. A reduction in the sample size and complexity of the system increases the significance of the sampling weights. 相似文献
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A 4% solar energy efficiency has been achieved for photogeneration of dihydrogen (H2) using MoS
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2−
as catalyst, when the anode compartment of a photogalvanic cell is illuminated. The generated photocurrent rises slowly with
time and reaches a limiting value. Ten hours after the reaction starts, a secondary dark reaction sets in which produces H2 and photocurrent even when the light is switched off. Possible mechanisms in both cases have been suggested. 相似文献
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Weiyan Wang Jinhua Huang Wei Xu Junjun Huang Yuheng Zeng Weijie Song 《Journal of Materials Science: Materials in Electronics》2013,24(6):2122-2127
The boron(B)- and phosphorous(P)-doped microcrystalline silicon (Si) thin films were prepared by magnetron sputtering of heavily B- and P-doped Si targets followed by rapid thermal annealing (RTA), their electrical properties were characterized by temperature-dependent Hall and resistivity measurements. It was observed that the dark conductivity and carrier concentration of the 260 nm B-doped Si films annealed at 1,100 °C in Ar were 3.4 S cm?1 and 1.6 × 1019 cm?3, respectively, which were about one order of magnitude higher than that of P-doped Si films. The activation energy of the B- and P-doped Si films were determined to be 0.23 eV and 0.79 eV, respectively. The dark conductivity of B- and P-doped Si films increased with the increase of film thickness, RTA temperature, and the incorporation of H2 in Ar during RTA. The present work provides an easy and non-toxic method for the preparation of doped microcrystalline Si thin films. 相似文献
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Fabrice Schmidt Nicolas Pirc Marcel Mongeau Francisco Chinesta 《International Journal of Material Forming》2011,4(1):73-82
Optimization and inverse identification are two procedures usually encountered in many industrial processes reputed gourmand for the computing time view point. In fact, optimization implies to propose a trial solution whose accuracy is then evaluated, and if needed it must be updated in order to minimize a certain cost function. In the case of mold cooling optimization the evaluation of the solution quality needs the solution of a thermal model, in the whole domain and during the thermal history. Thus, the optimization process needs several iterations and then the computational cost can become enormous. In this work we propose the use of model reduction for accomplishing this kind of simulations. Thus, only one thermal model is solved using the standard discretization technique. After that, the most important modes defining the temperature evolution are extracted by invoking the proper orthogonal decomposition, and all the other thermal model solutions are performed by using the reduced order approximation basis just extracted. The CPU time savings can be impressive. 相似文献
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《Nanostructured Materials》1994,4(5):559-568
A comparative review is given of laser ablation generation of ultrafine particles (UFPs: size range about 1–100 nm) in gas flows carried out by different research groups. Common features of the laser ablation deposition (LAD) method obtained for different materials (mainly metals or oxides) and lasers are discussed. Special emphasis is given to CO2-LAD of oxide UFPs (see (1)) for elucidation of basic mechanisms of particle formation and the LAD process. 相似文献
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S. H. Lo 《International journal for numerical methods in engineering》1991,31(4):689-707
A general and efficient remeshing algorithm is presented for the discretization of arbitrary planar domains into triangular elements in consistency with the given node spacing function. The contour lines of the node spacing function at suitable calculated levels provide the natural lines of division of the problem domain into subregions, where finite element meshes of different element sizes are generated using the available general-purpose mesh generators.1, 2 Examples of remeshing for various node spacing functions are given to illustrate that high-quality gradation meshes can be generated automatically without any user's intervention by this simple contour line method. 相似文献
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Annan JD Hargreaves JC 《Philosophical transactions. Series A, Mathematical, physical, and engineering sciences》2007,365(1857):2077-2088
In this paper, we review progress towards efficiently estimating parameters in climate models. Since the general problem is inherently intractable, a range of approximations and heuristic methods have been proposed. Simple Monte Carlo sampling methods, although easy to implement and very flexible, are rather inefficient, making implementation possible only in the very simplest models. More sophisticated methods based on random walks and gradient-descent methods can provide more efficient solutions, but it is often unclear how to extract probabilistic information from such methods and the computational costs are still generally too high for their application to state-of-the-art general circulation models (GCMs). The ensemble Kalman filter is an efficient Monte Carlo approximation which is optimal for linear problems, but we show here how its accuracy can degrade in nonlinear applications. Methods based on particle filtering may provide a solution to this problem but have yet to be studied in any detail in the realm of climate models. Statistical emulators show great promise for future research and their computational speed would eliminate much of the need for efficient sampling techniques. However, emulation of a full GCM has yet to be achieved and the construction of such represents a substantial computational task in itself. 相似文献
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Nasrollahzadeh Mahmoud Jaleh Babak Baran Talat Varma Rajender S. 《Clean Technologies and Environmental Policy》2020,22(2):325-335
Clean Technologies and Environmental Policy - Pd nanoparticles (NPs)/reduced graphene oxide (RGO) nanocomposite was prepared in a one-pot process by using Euphorbia stenoclada extract as... 相似文献
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The advantages of a grating interferometer for the generation of large diffraction gratings are demonstrated. In a one- and a two-stage process, high-quality gratings of 120 and 200 mm, respectively, were made with optics no larger than 50 mm together with an argon-ion laser with no line narrowing or beam stabilization and a rotating diffuser for improved beam uniformity. 相似文献
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We theoretically investigate the generation of ultra broadband supercontinuum from helium atoms exposed to a linearly polarized mid-infrared field. By adopting a UV trigger pulse to the mid-infrared field, the continuous harmonic yields are significantly enhanced by 3.5 orders, and a supercontinuum with the width of 230?eV is observed. The spectrum can support a sub-20 as pulse, which is below one atomic unit of time (24 as). The short quantum path is selected by adjusting the time delay between the UV pulse and the mid-infrared pulse, then broadband single 70 as pulses with tunable central wavelengths are obtained, which can be extended to the ‘water window’ region (284–543?eV). 相似文献
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A.R. Lipski R.S. Lefferts 《Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment》2011,655(1):41-43
A straightforward method of making tungsten targets from tungsten oxide powder on Cu backing is presented. A ceramic crucible containing WO3 powder placed on a copper foil is heated in hydrogen atmosphere at temperatures ranging from 650 up to 850 °C. The resulting thickness of tungsten deposited in our trials was in the range of 0.5-3.4 mg/cm2. 相似文献
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We report 32% efficient frequency doubling of single-frequency 1029 nm light to green light at 514.5 nm using a single-pass configuration. A congruent composition, periodically poled magnesium-doped lithium niobate (PPMgLN) crystal of 50 mm length was used to generate a second-harmonic power of 2.3 W. To our knowledge, this is the highest reported power and efficiency achieved in the second-harmonic generation of single-frequency green light in a single-pass configuration. 相似文献
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Şahin Kaya Özdemir Adam Miranowicz Masato Koashi Nobuyuki Imoto 《Journal of Modern Optics》2013,60(5-6):977-984
Generation of arbitrary superposition of vacuum and one-photon states using a quantum scissors device (QSD) is studied. The device allows the preparation of states by truncating an input coherent light. Optimum values of the intensity of the coherent light for the generation of any desired state using the experimentally feasible QSD scheme are found. 相似文献