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排序方式: 共有632条查询结果,搜索用时 46 毫秒
1.
Amini Amir Jafari Azin Vafaei Mostafa Mahmoodian Mehrnoosh 《Journal of Materials Science: Materials in Electronics》2022,33(3):1293-1306
Journal of Materials Science: Materials in Electronics - The main weakness of polymer gas sensors is its stability. Here, we report stability enhancement of a 100 nm polypyrrole (PPy) thin... 相似文献
2.
Imaging of the optic disc and retinal nerve fiber layer: the effects of age, optic disc area, refractive error, and gender. 总被引:3,自引:0,他引:3
Christopher Bowd Linda M Zangwill Eytan Z Blumenthal Cristiana Vasile Andreas G Boehm Parag A Gokhale Kourosh Mohammadi Payam Amini Timothy M Sankary Robert N Weinreb 《Journal of the Optical Society of America. A, Optics, image science, and vision》2002,19(1):197-207
We cross-sectionally examined the relationship between age, optic disc area, refraction, and gender and optic disc topography and retinal nerve fiber layer (RNFL) measurements, using optical imaging techniques. One eye from each of 155 Caucasian subjects (age range 23.0-80.8 y) without ocular pathology was included. Measurements were obtained by using the Heidelberg Retina Tomography (HRT), the GDx Nerve Fiber Analyzer, and the Optical Coherence Tomograph (OCT). The effects of age were small (R2 < 17%) and were limited to specific HRT, GDx, and OCT parameters. Disc area was significantly associated with most HRT parameters and isolated GDx and OCT parameters. Refraction and gender were not significantly associated with any optic disc or RNFL parameters. Although effects of age on the optic disc and RNFL are small, they should be considered in monitoring ocular disease. Optic disc area should be considered when cross-sectionally evaluating disc topography and, to a lesser extent, RNFL thickness. 相似文献
3.
Bahman Bohloli Bo Ronge Gunnar Gustafson 《Bulletin of Engineering Geology and the Environment》2002,61(1):43-47
Mechanical testing and ultrasonic measurements were used to establish the properties of metamorphic rocks in different directions
of the foliation plane. Tests were undertaken on 42 mm diameter specimens cored at right angles to the foliation of gneissic
rocks from southwest Sweden. Ultrasonic and tensile testing was carried out in three diametral directions and the data for
each direction were compared. Coefficients, failure load anisotropy and velocity anisotropy were obtained. An anisotropy coefficient
of 3% was detected by ultrasonic measurements, while the Brazilian tests indicated 15%. The study has shown that an anisotropy
coefficient of the foliation plane is present, albeit small.
Electronic Publication 相似文献
4.
R. Zarei M. Amini S. M. Taheri A. H. Rezaei 《Soft Computing - A Fusion of Foundations, Methodologies and Applications》2012,16(1):165-174
In Classical Bayesian approach, estimation of lifetime data usually is dealing with precise information. However, in real
world, some informations about an underlying system might be imprecise and represented in the form of vague quantities. In
these situations, we need to generalize classical methods to vague environment for studying and analyzing the systems of interest.
In this paper, we propose the Bayesian estimation of failure rate and mean time to failure based on vague set theory in the
case of complete and censored data sets. To employ the Bayesian approach, model parameters are assumed to be vague random
variables with vague prior distributions. This approach will be used to induce the vague Bayes estimate of failure rate and
mean time to failure by introducing and applying a theorem called “Resolution Identity” for vague sets. In order to evaluate
the membership degrees of vague Bayesian estimate for these quantities, a computational procedure is investigated. In the
proposed method, the original problem is transformed into a nonlinear programming problem which is then divided into eight
subproblems to simplifying computations. 相似文献
5.
Barimani Samaneh Amini Amir Chaharmahali Iman 《Journal of Computational Electronics》2021,20(3):1332-1342
Wave absorbers are considered to be fundamental building blocks for the manipulation of light. Almost all optical systems exploit absorbers to realize some functions. A highly tunable wide-band THz absorber is presented herein. Utilizing a dual-bias scheme with a single graphene layer leads to greater freedom to control the absorption response, while a conventional periodic array of graphene ribbons and a layer of graphene sheet are also exploited. Also, a circuit model representation for all the constituent parts of the proposed absorber is developed with an evolved design methodology. According to the simulation results, wide-band absorption from 3.5 to 6 THz is achieved.
相似文献6.
Bahman ZareNezhad 《Korean Journal of Chemical Engineering》2007,24(6):942-946
A 2-D network-of-zones model is extended and applied to a reactive precipitation process in batch mode. The simulations are
performed for a network of size 2 × (10 × 10) for an elementary reaction through the solution of 1400 ODEs. The complicated
interactions between mixing efficacy and the system kinetics are systematically investigated. When the stirrer speed is very
slow, the crystal size distribution (CSD) of the product in the precipitator is determined by the intensity of mixing. Conversely,
at higher stirrer speed, the CSD is controlled by the system kinetics. More effective mixing leads to an increase in the number
of crystals, a reduction of the average size and a narrower crystal size distribution. The extended network-of-zones model
presented in this work can be used conveniently for integrating computational fluid dynamics and reactive precipitation processes. 相似文献
7.
Rama Subba Reddy Gorla Jorge E. Gatica Bahman Ghorashi Pijarn Ineure Larry W. Byrd 《Chemical Engineering Communications》2004,191(5):718-731
Heat transfer enhancement in an evaporating thin liquid film utilizing a electric field under isothermal interfacial condition is presented. A new mathematical model subjected to van der Waals attractive forces, capillary pressure, and an electric field is developed to describe the heat transfer enhancement in the evaporating thin liquid film. The effect of the electrostatic field on the curvature of the thin film, evaporative flux, pressure gradient distribution, heat flux, and heat transfer coefficient in the thin film is presented. The results show that applying an electric field can enhance heat transfer in a thin liquid film significantly. In addition, utilizing electric fields on the evaporating film will be a way to expand the extended meniscus region to attain high heat transfer coefficients and high rates of heat flux. 相似文献
8.
Frequency-domain photoacoustic radar (FD-PAR) imaging of absorbers in turbid media and their comparison and/or validation as well as co-registration with their corresponding ultrasound (US) images are demonstrated in this paper. Also presented are the FD-PAR tomography and the effects of reducing the number of scan lines (or angles) on image quality, resolution, and contrast. The FD-PAR modality uses intensity-modulated (coded) continuous wave laser sources driven by frequency-swept (chirp) waveforms. The spatial cross-correlation function between the PA response and the reference signal used for laser source modulation produces the reconstructed image. Live animal testing is demonstrated, and images of comparable signal-to-noise ratio, contrast, and spatial resolution were obtained. Various image improvement techniques to further reduce absorber spread and artifacts in the images such as normalization, filtering, and amplification were also investigated. The co-registered image produced from the combined US and PA images provides more information than both images independently. The significance of this work lies in the fact that achieving PA imaging functionality on a commercial ultrasound instrument could accelerate its clinical acceptance and use. This work is aimed at functional PA imaging of small animals in vivo. 相似文献
9.
Dirk Obergfell Bahman Azarhoushang Andrés Fabián Lasagni 《Advanced Engineering Materials》2023,25(19):2300757
Due to its high corrosion resistance and mechanical properties, stainless steel is commonly used in various industrial applications. Although different types of stainless steel are similar in their chemical composition, they can differ significantly in their thermal diffusivity. This property is relevant in the ability of a material to conduct heat and thus, in laser processing. In this frame, this study compares the ablation efficiency and characteristics of polished stainless steel samples of the alloys AISI 304, AISI 420, and AISI 316Ti. They are irradiated with single ultrashort pulses having pulse durations between 250 fs and 10 ps as well as using GHz burst modii. The goal is to investigate the differences in both the ablation threshold and the ablation rate to improve the ablation efficiency. The results show that shorter pulse durations lead to a more efficient ablation process. On the other hand, GHz bursts are found to be, in general, less efficient. In addition, there is a significant difference in the surface morphology depending on the process parameters. The differences in the thermal diffusivity do not significantly influence the ablation threshold fluence but surface morphology and the ablation rate. 相似文献
10.
We address the problem of learning text categorization from a corpus of multilingual documents. We propose a multiview learning, co-regularization approach, in which we consider each language as a separate source, and minimize a joint loss that combines monolingual classification losses in each language while ensuring consistency of the categorization across languages. We derive training algorithms for logistic regression and boosting, and show that the resulting categorizers outperform models trained independently on each language, and even, most of the times, models trained on the joint bilingual data. Experiments are carried out on a multilingual extension of the RCV2 corpus, which is available for benchmarking. 相似文献