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Ellipsometry of ultrathin transparent films. Some aspects of optimum experimental conditions choice

OPTICS COMMUNICATIONS 2024年 552卷

作者： Kostruba, A. Stetsyshyn, Yu Savaryn, V. Koda, E. Stybel, V. Mayevska, S. Kernytskyy, I. Stepan Gzhytskyi Natl Univ Vet Med & Biotechnol Lv Pekarska Str 50 UA-79010 Lvov Ukraine Lviv Polytech Natl Univ Stepan Bandera Str 12 UA-79013 Lvov Ukraine Warsaw Univ Life Sci Nowoursynowska 166 PL-02787 Warsaw Poland Lviv State Univ Phys Culture Kostyushko Str 11 UA-79007 Lvov Ukraine

Reflection ellipsometry in visible and infrared range, which enables the analysis of isotropic thin films, is one approach that is extremely sensitive and accurate. There are a few restrictions with this technique when analyzing ultra-thin transparent film (UTTF) structures. In our study, the issue of the independent determination of two parameters of a transparent film that is extremely thin (d < 10 nm) is examined from the standpoint of the optimal conditions choosing for an ellipsometric experiment. An original method to calculation the errors in the main parameters of UTTF depending on the experimental conditions is proposed. One analyzed the influence of the substrate optical parameters and the incidence angle of light on the sensitivity of ellipsometric data. The analysis shows that under certain experimental conditions, the sensitivity of ellipsometric measurements allows to independently determine both the refractive index and the thickness of a transparent film down to 3 nm thick.

关键词： Ellipsometry Ultra -thin transparent film parameters correlation Inverse ellipsometry problem Measurements accuracy and sensitivity

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NON-UNIFORM TIP CLEARANCE EFFECTS ON TURBOCHARGER COMPRESSOR PERFORMANCE

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ASME Turbo Expo: Turbomachinery Technical Conference and Exposition

作者： Adjei, Richard A. Wang, Weizhe Peng, Di Liu, Yingzheng Bamba, Takahiro Shanghai Jiao Tong Univ Sch Mech Engn 800 Dongchuan Rd Shanghai 200240 Peoples R China IHI Corp Vehicular Turbocharger Business Unit Isogo Ku 1 Shin Nakahara Cho Yokohama Kanagawa 2358501 Japan

ISBN: (纸本)9780791851005

In most turbocharger compressors, diffusers are designed with contractions along the passage mainly for delaying surge. The width ratio parameter, B, which defines the diffuser inlet width to diameter ratio significantly affects the losses in the diffuser. Changes to tip clearance, for example, due to the impeller rubbing the shroud casing changes the fluid flow angle at the impeller exit. The sensitivity of the absolute flow angle to the width ratio parameter has a significant influence on diffuser effectiveness and stage performance. This paper reports an investigation of tip clearance sensitivity to vaneless diffuser and stage performance of a turbocharger compressor. To assess the correlation between performance parameters and the tip clearance, Design of Experiments (DoE) was used to sample 40 design cases by changing the clearance at the leading (LE) and trailing edges (TE) of the impeller. parameters correlation was subsequently used to determine their relationship. The key findings were that stage efficiency and pressure ratio increased linearly with decreasing LE and TE clearances having a maximum sensitivity value R = 0.7. Diffuser Cp showed a strong positive correlation for TE and a weak negative correlation for LE. Similarly, work input and diffuser loss coefficient showed an inverse relation to diffuser Cp with a maximum R value of 0.9. It was concluded that increasing the tip clearance at TE improves the diffuser effectiveness. The main source of low diffuser Cp for small tip clearances was due to higher diffusion losses as a result of flow non uniformity when the width ratio and absolute flow angle were large. As the width ratio decreases along the passage appreciable frictional losses occur in larger tip clearance further increasing the losses. The absolute flow angle and width ratio were observed to be key to diffuser and stage performance.

关键词： parameters correlation non-uniform tip clearance Design of Experiments

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ENVIRONMENTAL MODELING & ASSESSMENT 2017年第5期22卷 503-521页

作者： Razmkhah, Homa AkhoundAli, Ali-Mohammad Radmanesh, Fereydoun Islamic Azad Univ Marvdasht Branch Dept Water Engn Marvdasht Iran Shahid Chamran Univ Ahvaz Dept Hydrol Coll Water Sci & Engn Ahvaz Iran

Hydrological models are widely used to investigate practical issues of water resources. Parametric uncertainty is considered as one of the most important sources of uncertainty in environmental researches. Generally, it is assumed that the parameters are independent mutually, but correlation within the parameter space is an important factor having the potential to cause uncertainty. The objective and innovation of this study was to address the effects of parameters correlation on a continuous hydrological model uncertainty. HEC-HMS with soil moisture accounting (SMA) infiltration method was used to model daily flows and simulate certainty bounds for Karoon III basin, southwest of IRAN, in two scenarios, independent and correlated parameters using 2-copula. The parameters were represented by probability distributions, and the effect on prediction error were evaluated using Latin hypercube sampling (LHS) on Monte Carlo simulation (MCS). Saturated hydraulic conductivity (K), Clark storage-coefficient (R), and time of concentration (tc) were chosen for investigation, based on observed sensitivity analysis of simulated peak over threshold (POT). One hundred runs were randomly generated from 100 parameter sets captured from LHS of parameters distributions in each sub-basin. Using generated parameter sets, 100 continuous hydrographs were simulated and values of certainty bounds calculated. Results showed that when 2-copula correlated R and tc, with 0.656 Kendall's Tau and 0.818 Spearman's Rho coefficients, were propagated, decreasing of outputs' sharpness was more than when considering K and R (K-R), with 0.166 and 0.262;therefore, incorporation of correlations in the MCS is important, especially when the correlation coefficients exceed 0.65. The model was evaluated at the outlet of the basin using daily stream flow data. Model reliability was better for above-normal flows than normal and below-normal. Reliability increases of simulated flow when considering correlated R-t

关键词： Uncertainty propagation Latin hypercube sampling Copula parameters correlation Monte Carlo simulation

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DEVELOPMENT OF BOLTED FLANGE DESIGN TOOL BASED ON FINITE ELEMENT ANALYSIS AND ARTIFICIAL NEURAL NETWORK

DEVELOPMENT OF BOLTED FLANGE DESIGN TOOL BASED ON FINITE ELE...

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ASME International Mechanical Engineering Congress and Exposition (IMECE2015)

作者： Yildirim, Alper Akay, Ahmet Arda Gulasik, Hasan Coker, Demirkan Gurses, Ercan Kayran, Altan Middle East Tech Univ Dept Aerosp Engn Ankara Turkey ASELSAN AS Ankara Turkey

ISBN: (纸本)9780791857526

In bolted flange connections, commonly utilized in aircraft engine designs, structural integrity and minimization of the weight are achieved by the optimum combination of the design parameters utilizing the outcome of Many structural analyses. Bolt size, the number of bolts, bolt locations, casing thickness, flange thickness, bolt preload, and axial external force are some of the critical design parameters in bolted flange connections. Theoretical analysis and finite element analysis (FEA) are two main approaches to perform structural analysis of bolted flange connections. Theoretical approaches require the simplification of the geometry and are generally oversafe. In contrast, finite element analysis is more reliable but at the cost of high computational power. In this paper, a methodology is developed for iterative analyses of bolted flange that utilizes artificial neural network approximation of a database formed with more than ten thousand non-linear analyses with contact algorithm. In the design tool, a structural analysis database is created by taking permutations of the parametric variables. The number of intervals for each variable in the upper and lower range of the variables is determined with the parameters correlation study in which the significance of parameters are evaluated. The prediction of the ANN based design tool is then compared with FEA results and the theoretical approach of ESDU. The results show excellent agreement of the ANN based design tool with the actual non-linear finite element analysis results within the training limits of the ANN.

关键词： bolted flange connection artificial neural network parameters correlation FEA contact analysis

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Automatic parameter extraction technique for gate leakage current modeling in double gate MOSFET

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SOLID-STATE ELECTRONICS 2013年第Nov.期89卷 111-115页

作者： Darbandy, Ghader Gneiting, Thomas Alius, Heidrun Alvarado, Joaquin Cerdeira, Antonio Iniguez, Benjamin Univ Rovira & Virgili Dept Engn Elect Elect & Automat Tarragona Spain AdMOS GmbH Adv Modeling Solut D-72636 Frickenhausen Germany Benemerita Univ Autonoma Puebla Res Ctr Semicond Devices Puebla 72570 Mexico CINVESTAV Dept Elect Engn Mexico City 07300 DF Mexico

Direct Tunneling (DT) and Trap Assisted Tunneling (TAT) gate leakage current parameters have been extracted and verified considering automatic parameter extraction approach. The industry standard package IC-CAP is used to extract our leakage current model parameters. The model is coded in Verilog-A and the comparison between the model and measured data allows to obtain the model parameter values and parameters correlations/relations. The model and parameter extraction techniques have been used to study the impact of parameters in the gate leakage current based on the extracted parameter values. It is shown that the gate leakage current depends on the interfacial barrier height more strongly than the barrier height of the dielectric layer. There is almost the same scenario with respect to the carrier effective masses into the interfacial layer and the dielectric layer. The comparison between the simulated results and available measured gate leakage current transistor characteristics of Trigate MOSFETs shows good agreement. (C) 2013 Elsevier Ltd. All rights reserved.

关键词： Automatic parameter extraction parameters correlation Direct tunneling TAT DG MOSFET

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Radiated energy evolution during seismic sequences

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PHYSICS OF THE EARTH AND PLANETARY INTERIORS 2012年 196卷 49-61页

作者： Gentili, Stefania Ctr Ric Sismol Ist Nazl Oceanog & Geofis Sperimentale I-33100 Udine Italy

In this paper, I propose a new equation describing the evolution of seismic sequences, based on radiated energy. The evolution of radiated energy in time is described as function of the p and c parameters of the Modified Omori Law and of the energy radiated within a short time following the mainshock. By using the energy rather than the number of events in describing seismic sequences. I circumvent the problem of missing weak aftershocks close in time to the mainshock, because most of the total energy is contained in largest events. In addition, I propose an equation describing the difference in magnitude between the mainshock and the strongest aftershock as function of the energy radiated in a short time after the mainshock, of p, c, and of the parameter b of the Gutenberg Richter equation. An application to California sequences shows values of p in the range [0.65, 1.5] and c in the range [0, 0.25] and no dependence of c on the difference between mainshock and cutoff magnitude. (C) 2012 Elsevier B.V. All rights reserved.

关键词： Omori Law Gutenberg Richter law Seismic sequences c Value estimation Energy evolution parameters correlation

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COMPUTATIONAL FLUID DYNAMICS CALCULATIONS OF WASTE-TO-ENERGY PLANT COMBUSTION CHARACTERISTICS

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THERMAL SCIENCE 2011年第1期15卷 1-16页

作者： Kapitler, Miran Samec, Niko Kokalj, Filip Univ Maribor Fac Mech Engn Lab Combust & Environm Engn Inst Power Proc & Environm Engn Maribor Slovenia

The combustion process for using municipal solid waste as a fuel within a waste to energy plant calls for a detailed understanding of the following phenomena. Firstly, this process depends on many input parameters such as proximate and ultimate analyses, the season of the year. primary and secondary inlet air velocities and, secondly, on output parameters such as the temperatures or mass fraction of the combustible products. The variability and mutual dependence of these parameters can be difficult to manage in practice. Another problem is how these parameters can be tuned to achieving optimal combustible conditions with minimal pollutant emissions, during the plant-design phase. In order to meet these goals, a waste-to-energy plant with bed combustion was investigated by using computational fluid-dynamics approach. The adequate variable input boundary conditions based on the real measurement are used and the whole computational work is updated using real plant geometry and the appropriate turbulence, combustion, or heat transfer models. The operating parameters were optimized on output parameters through a trade-off study. The different operating conditions were varied and the combustible products were predicted and visualized. Finally, the response charts and matrix among the input and output parameters during the optimization process are presented, which monitored the dependence among these parameters.

关键词： municipal solid waste bed combustion computational fluid dynamics numerical optimization goal driven optimization trade-off study parameters correlation

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NUMERICAL OPTIMIZATION OF A WASTE-TO-ENERGY PLANT UNDER DIFFERENT OPERATING CONDITIONS

NUMERICAL OPTIMIZATION OF A WASTE-TO-ENERGY PLANT UNDER DIFF...

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8th ASME/JSME Thermal Engineering Joint Conference

作者： Samec, Niko Kapitler, Miran Kokalj, Filip Univ Maribor Fac Mech Engn SLO-2000 Maribor Slovenia

ISBN: (纸本)9780791854556

The combustion process for using municipal solid waste (MSW) as a fuel within a waste-to-energy plant calls for a detailed understanding of the following phenomena. Firstly, this process depends on many input parameters such as MSW proximate and ultimate analysis, the season of the year, primary and secondary air-inlet velocity and, secondly, on output parameters such as the temperatures or mass-flow rates (MFR) of the combustible products. The variability and mutual dependence of these parameters can be difficult to manage in practice. Moreover, another problem is how these parameters can be tuned to achieving optimal combustion with minimal pollutant emissions during the initial plant-design phase. In order to meet these goals, a waste-to-energy plant with bed-combustion was investigated by using a computational fluid dynamics (CFD) approach with ANSYS CFX 12.0 code within a WORKBENCH 2 environment. In this paper, the adequate variable input boundary conditions based on the real measurement and practical calculations of known MSW composition compared with other authors are used and the whole computational work is updated using real plant geometry and the appropriate turbulence, combustion and heat transfer models. Furthermore, the operating parameters were optimized on output parameters through a trade-off study. The different operating conditions were varied and the fluid flow direction, residence time, temperature field, velocity-field, nitric oxide formation and combustion products through the plant's combustion chamber and preheat intersection in 3D were predicted and visualized. Optimization in real-time has showed the amounts for each input parameter when meeting the optimal operating conditions. Finally, the response charts between the input and output parameters are presented in order to monitor the dependence among these parameters. Further simulations have to be done to include the geometry dimensions as input parameters when applying the CDF simulation

关键词： Municipal solid waste (MSW) modeling bed combustion computational fluid dynamics (CFD) operating conditions numerical optimization goal driven optimization trade-off study parameter sensitivity response charts parameters correlation

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Estimation of Semi Automatic versus Automatic Choice Methods on Breast Dose

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11th International Congress of the IUPESM/World Congress on Medical Physics and Biomedical Engineering

作者： Gershan, Vesna Univ Clin Radiol Skopje Macedonia

ISBN: (纸本)9783642038785

In order to improve the image quality, the protocol for semi automatic choice of technical parameters on SIEMENS Mamomat 3 was optimized. The radiographers chose kVp parameter depending on breast size and type. At the same time, in clinical use was another mammography machine, HOLOGIC Affinity, with automatic selection of beam quality and the same film/screen combination. An opportunity was used to estimate the impact of the beam quality choice of dose. Dose Surveys were done for 199 exposures performed with semi automatic, and for other 295 exposures performed with automatic selection of technical parameters. A correlation was found between ESAK - breast thickness and ESAK-kVp, ESAK-mAs for both mammography machines. correlations between MGD and thickness, MGD - kVp and MGD-mAs were done as well. The results show that there are higher correlations ESAK - breast thickness and ESAK - kVp for semi automatic than for the automatic selection of the technical parameters. The same conclusion is valid for MGD - breast thickness and MGD-kVp correlation. Usually, automatic choice method provides ESAK correlation to breast thickness and kVp higher than semi automatic method. It is expected that MGD correlation to breast thickness and kVp parameter for automatic method will be higher, also. But, this work does not confirm this statment for our machines, although fact that the mammography machine with automatic choice of parameters met all QC criteria.

关键词： bream quality breast dose parameters correlation

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correlation between the parameters of the aftershock rate equation: Implications for the forecasting of future sequences

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PHYSICS OF THE EARTH AND PLANETARY INTERIORS 2006年第1-2期156卷 41-58页

作者： Gasperini, Paolo Lolli, Barbara Univ Bologna Alma Mater Studiorum Dipartimento Fis I-40127 Bologna Italy

We analyzed the correlations among the parameters of the Reasenberg and Jones [Reasenberg, P.A., Jones, L.M., 1989. Earthquake hazard after a mainshock in California, Science 243, 1173-1176] formula describing the aftershock rate after a mainshock as a function of time and magnitude, on the basis of parameter estimates made in previous works for New Zealand, Italy and California. For all of three datasets we found that the magnitude-independent productivity a is significantly correlated with the b-value of the Gutenberg-Richter law and, in some cases, with parameters p and c of the modified Omori's law. We also found significant correlations between p and c but, different from some previous works, not between p and b. We verified that assuming a coefficient for mainshock magnitude alpha approximate to 2/3b (instead of b) removes the correlation between a and b and improves the ability to forecast the behavior of Italian sequences occurred from 1997 to 2003 on the basis of average parameters estimated from sequences occurred from 1981 to 1996. This assumption well agrees with direct alpha estimates made in the framework of an epidemic type model (ETAS) from the data of some large Italian sequences. Our results suggest a modification of the original Reasenberg and Jones (1989) formulation leading to predict lower rates (and probabilities) for stronger mainshocks and conversely higher rates for weaker ones. We also inferred that the correlation of a with p and c might be the consequence of the trade-off between the two parameters of the modified Omori's law. In this case the correlation can be partially removed by renormalizing the time-dependent part of the rate equation. Finally, the absence of correlation between p and b, observed for all the examined datasets, indicates that such correlation, previously inferred from theoretical considerations and empirical results in some regions, does not represent a common property of aftershock sequences in different part of th

关键词： aftershocks forecasting Omori law Gutenberg-Richter law parameters correlation

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