Academic literature on the topic 'Make-out coefficient'
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Journal articles on the topic "Make-out coefficient"
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Li, Ting, Qing Jia, and Zhi Gang Yang. "The Influence of Rotating Wheels on Vehicle Aerodynamics." Applied Mechanics and Materials 246-247 (December 2012): 543–47. http://dx.doi.org/10.4028/www.scientific.net/amm.246-247.543.
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Full scaled simplified model and production vehicle were applied to make a research on the local and global flow characteristics. Two different conditions including stationary and rotation were employed in computational simulation by steady RNS Navier-Stokes calculation. Further, detailed analysis on flow, surface pressure coefficient, drag coefficient and lift coefficient affected by rotating wheel figure out that rotating wheel has a significant influence on the flow around wheel and vehicle. Pressure difference, drag coefficient and lift coefficient are decreased by rotation, which improve aerodynamic performance.
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Susanto, Chyntia, Helen Leonora, and Carmel Meiden. "META ANALISIS: DETERMINAN EARNINGS RESPONSE COEFFICIENT PADA BEBERAPA PENELITIAN SKRIPSI DI INDONESIA." Jurnal Proaksi 9, no. 2 (May 10, 2022): 127–43. http://dx.doi.org/10.32534/jpk.v9i2.2743.
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Investors need information, one of which is the company's accounting profit figures shown in its financial statements, to make investment decisions. The information is good or bad news that generates various investor responses, and underlies the earnings response coefficient research. Research on the determinants of earning response coefficients has been widely carried out with different research results. This study aims to organize and find the consistency of the results of previous studies. The object of the research is a thesis on the determinants of earning response coefficient with a research period of 2011-2019. The data collection technique used is the observation technique and the sample selection technique used is the purposive sampling technique, and uses meta-analysis as a research analysis technique. The results of this study indicate that earnings persistence, capital structure, firm size, corporate social responsibility disclosure, profitability, and leverage affect the earning response coefficient.
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Dong, Xianshan, Qinwen Huang, Junhua Zhu, Wei Xu, and Ping Lai. "Effect of excitation voltage on bias temperature coefficient of MEMS sandwich accelerometer." International Journal of Modern Physics B 33, no. 12 (May 10, 2019): 1950112. http://dx.doi.org/10.1142/s0217979219501121.
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In MEMS closed-loop accelerometer, excitation voltage is an important design parameter that is related to many performance indexes, and the bias temperature coefficient is a key point for MEMS accelerometer. But the effect of excitation voltage on bias temperature coefficient is not clear and their relation has not yet been established. This paper studies the effect of excitation voltage on bias temperature coefficient of MEMS sandwich accelerometer. The mechanism of their relation is point out, and experiments of bias temperature drift with different excitation voltages are carried out. The measured results show that the excitation voltage influences the bias temperature coefficient of MEMS sandwich accelerometer greatly, and the frame of sensor structure is the main source of bias temperature drift in MEMS sandwich accelerometer. This paper is also helpful for researchers to further understand the source of bias drift in MEMS sandwich accelerometer and make corresponding improvement.
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Wang, Liyan, Jiatao Yan, Qi Wang, Binghui Wang, and Aimable Ishimwe. "Study on Permeability of Steel Slag and Steel Slag Modifying Silt Soil as New Geo-Backfill Materials." Advances in Civil Engineering 2019 (July 1, 2019): 1–14. http://dx.doi.org/10.1155/2019/5370748.
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To make steel slag being reasonably used in geotechnical backfilling projects or soft foundation treatment projects, three kinds of steel slag such as fine, coarse, and gravel steel slag were studied through particle analysis tests, relative density tests, and specific gravity tests to obtain basic physical parameters. Considering the influence of relative density, gradation, and other factors, constant head permeability tests of pure steel slag and variable head permeability tests of modified silt soil with different mixing contents of steel slag were carried out to test permeability coefficients under various working conditions. Prediction formulas on the permeability coefficients of the three kinds of pure steel slag and steel slag-treated silt soil were, respectively, deduced. It was concluded that the permeability coefficient of pure steel slag was greatly influenced by particle size and relative density, similar to the case of permeability coefficients of fly ash and fine sand in their dense states, and the larger the relative density was, the smaller the permeability coefficient was. The permeability coefficient of steel slag-treated silt soil increased with increasing of mixing content of steel slag, showing that steel slag can obviously improve the permeability performance of silt soil. Research results provide reference for design and construction on the application of steel slag in roadbed backfill, steel slag modifying silt soil, and other projects.
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Kuznetsov, A. V., A. A. Igolkin, A. I. Safin, and A. O. Pantyushin. "Mathematical model of acoustic characteristics of polyurethane foam used for sound absorption in aerospace engineering." VESTNIK of Samara University. Aerospace and Mechanical Engineering 20, no. 2 (July 9, 2021): 53–62. http://dx.doi.org/10.18287/2541-7533-2021-20-2-53-62.
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When solving the problem of reducing the acoustic load on the spacecraft during the launch and flight of the launch vehicle, finite element modeling of acoustic processes under the nose fairing is carried out. To successfully solve this problem, a mathematical model of the acoustic characteristics of the material used for sound insulation is required. The existing mathematical models of the acoustic characteristics of materials are not suitable for the material under consideration that can be used in rocket and space technology to increase the sound insulation of the payload fairing + transfer compartment assembly. To obtain the sound absorption coefficient of the material, an impedance tube measurement method with two microphones is used. Using the method of differential evolution, the coefficients of a mathematical model of acoustic characteristics of the Delany-Bazley type for the specified material are selected. The sound absorption coefficient obtained experimentally and that calculated using the obtained model are compared; the average and maximum values of the error are shown. The resulting model will make it possible to carry out finite element modeling of acoustic and vibroacoustic processes under the nose fairing, taking into account the location of the sound-absorbing material.
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Xie, Zhuojie, Yuhui Wang, and Qingxian Wu. "Battle damage assessment of surface warship formation based on improved gray relational analysis." Journal of Defense Modeling and Simulation: Applications, Methodology, Technology 15, no. 3 (November 1, 2017): 269–78. http://dx.doi.org/10.1177/1548512917740446.
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The paper analyzes the pros and cons of classical gray relational analysis on solving multi-target and multi-attribute problems, and presents an improved gray relational model to assess the battle damage of surface warship formations. First, with an entropy method and analytic hierarchy process, the subjective and objective weights of the index attributes are determined, respectively, and then they are combined with the product method to obtain the combined weight. Second, to make full use of the information carried by the index attributes, a polygon area formed by the adjacent points of the reference sequence curve and alternative sequence curve is used as gray relational coefficient. Third, by combining with the combined weight and the gray relational coefficients, an improved gray relational degree is thus determined. Finally, the numerical results illustrate that the battle damage assessment is generally consistent with the assessment results of experts, and the achieved result will provide important information to make a correct decision for carrying out a next strike.
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CUMMINGS, PETER, and XIAOBING FENG. "SHARP REGULARITY COEFFICIENT ESTIMATES FOR COMPLEX-VALUED ACOUSTIC AND ELASTIC HELMHOLTZ EQUATIONS." Mathematical Models and Methods in Applied Sciences 16, no. 01 (January 2006): 139–60. http://dx.doi.org/10.1142/s021820250600108x.
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We consider complex-valued acoustic and elastic Helmholtz equations with the first order absorbing boundary condition in a star-shaped domain in ℜN for N ≥ 2. It is known that the elliptic regularity coefficients depend on the frequency ω, and have singularities for both zero and infinite frequency. In this paper, we obtain sharp estimates for the coefficients with respect to large frequencies. It is proved that the elliptic regularity coefficients are bounded by first or second order polynomials in ω for large ω. The crux of our analysis is to establish and make use of Rellich identities for the solutions to the acoustic and elastic Helmholtz equations. Our results improve the earlier estimates of Refs. 10 and 11, which were carried out based on layer potential representations of the solutions of the Helmholtz equations.
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Irawan, Irawan, and Aqli Mursadin. "ANALISIS KINERJA AIR HEATER DI PLTU ASAM-ASAM UNIT 2." JTAM ROTARY 1, no. 1 (April 1, 2019): 17. http://dx.doi.org/10.20527/jtam_rotary.v1i1.1396.
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Indonesia as one of the largest coal producers utilizes this advantage by establishing a steam power plant, one of which is Borneo south PLTU power plant PT.PLN (persero) south of Borneo and Central Borneo Asam-Asam generation sector. One important component of PLTU is air heater to raise the combustion air temperature. Initial heating of ljungstrom type lattest regenerative air heater in PLTU Asam-Asam unit 2 is carried out cleaning and maintenance on seal and gas side surfaces to optimize heat transfer coefficient and ratio of air intake ratio exposed by forced draft fan and air heated by flue gas in heater air heater elements and transferred to the combustion chamber to make efficient use of new fuel. Measurements were carried out on August 9, 2017 for 2 hours to find out the average value of heat transfer coefficient and temperature comparison of entry and exit from air heater of Asam-Asam unit 2 steam power plant. This research was conducted to find out the value of heat transfer coefficient and air temperature ratio with measurement on the inlet and outlet for two hours. The results of the air heater performance analysis in in PLTU Asam-Asam unit 2 steam power plant in terms of the highest heat transfer coefficient was 62.75 W/m^2.℃ at 2:04 PM, while the lowest heat transfer coefficient was 62.37 W/m^2.℃ at 3:10 PM, and the average heat transfer coefficient is 62.50 W/m^2.℃ . While the highest water heater ratio 9.70 at 3:44 PM and the lowest ratio 8.32 at minute 3:09 PM, and the average water heater ratio 9.01. Heater water heater elements in good condition and performance in receiving and releasing heat. Keywords: Air Heater, Heat Transfer Coefficient, Temperature Ratio, Heating Elements
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Гавлина, Ольга Тихоновна, Сергей Игоревич Каргов, and Владимир Александрович Иванов. "The concept of gel diffusion in the kinetics of swelling and shrinking of a polystyrene sulfonic acid ion exchanger in the K+ form." Сорбционные и хроматографические процессы 21, no. 6 (January 8, 2022): 794–804. http://dx.doi.org/10.17308/sorpchrom.2021.21/3824.
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The kinetics of swelling and shrinking of polystyrene resins of the sulfonic acid type was investigated. The ion-exchange bead in the K+ form, equilibrated with a 0.1 M, 0.5 M, 1.0 M or 2 M KCl solution was placed into water and its diameter was measured continuously. In the reverse experiments, the bead, which came into equilibrium with water, was transferred into KCl solutions and the kinetics of grain shrinking was studied analogously. The experimental data were processed by using the theory of "gel diffusion", the parameter of which is the so-called gel diffusion coefficient, similar to the molecular diffusion coefficient. In contrast to previously published works, in which only the first term of the series in the corresponding equation was taken into account, in our work the first ten members of the series were taken into account. It turned out that it is necessary to take into account not only the first member of the series (as was done in previously published works), but also the second member of the series. It also turned out that the values of the obtained gel diffusion coefficient, obtained by this method, quite logically increased somewhat during the process of swelling (for example, in experiments with 1 M KCl from 2.1×10−6 to 3.0×10−6 cm2/s) and decreased somewhat during the process of shrinking. It was shown that the average values of the diffusion coefficients of the gel make it possible to adequately describe the main part of the kinetic curve. The concept of gel diffusion allows comparing the swelling kinetics of various polyelectrolyte gels in terms of diffusion coefficients, regardless of the particle shape, systematize data for various materials, and comparing their properties with the molecular diffusion of other substances.
It also turned out that in the very final parts (5-10%) of the kinetic curves a sharp decrease in the diffusion coefficient value was observed both in experiments with the swelling and shrinking of grains. It indicates that during the final stages there was a sharp deceleration of the process due to a change in its mechanism.
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GUO, SHENG-LI, ZHUN GUO, T. SUSDORF, and TIAN-DE CAO. "ABSORPTION, EMISSION AND NONLINEAR SPECTROSCOPIC CHARACTERIZATION OF REACTIVE DYE." Journal of Nonlinear Optical Physics & Materials 15, no. 04 (December 2006): 481–90. http://dx.doi.org/10.1142/s0218863506003414.
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An optical spectroscopic characterization is carried out on a reactive dye (reactive orange 1). This dye is widely applied in textile coloration. It is a potential candidate for photonics applications. Its absorption cross-section spectra are measured. A fluorescence spectroscopic characterization is undertaken by measuring the fluorescence quantum distributions and fluorescence quantum yields. The saturable absorption is studied by nonlinear transmission measurements with intense picosecond laser pulses (second harmonic pulses of a mode-locked Nd :glass laser). The nonlinear optical absorption and refraction coefficients are measured by using the top-hat Z-scan technique at a wavelength of 532 nm with 35 ps duration pulses. Reactive orange 1 has the two-photon absorption coefficient of 1.20 cm/GW and the nonlinear refraction coefficient of -7.33 × 10-6 cm2/GW, respectively. In reactive orange 1, there occurs fast ground-state recovery by internal conversion likely via conical intersections. Low excited-state absorption and fast ground-state absorption recovery make it an ideal candidate for passive mode-locking of picosecond and femtosecond lasers as well as for fast nonlinear optical gating.
Book chapters on the topic "Make-out coefficient"
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West, Geoffrey B. "The Large Coefficient Problem: Can We Make Sense Out of QCD Perturbation Theory?" In NATO ASI Series, 487–505. Boston, MA: Springer US, 1990. http://dx.doi.org/10.1007/978-1-4684-9054-1_32.
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Akeh, Ugbah Paul, Steve Woolnough, and Olumide A. Olaniyan. "ECMWF Subseasonal to Seasonal Precipitation Forecast for Use as a Climate Adaptation Tool Over Nigeria." In African Handbook of Climate Change Adaptation, 1613–30. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-45106-6_97.
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AbstractFarmers in most parts of Africa and Asia still practice subsistence farming which relies minly on seasonal rainfall for Agricultural production. A timely and accurate prediction of the rainfall onset, cessation, expected rainfall amount, and its intra-seasonal variability is very likely to reduce losses and risk of extreme weather as well as maximize agricultural output to ensure food security.Based on this, a study was carried out to evaluate the performance of the European Centre for Medium-range Weather Forecast (ECMWF) numerical Weather Prediction Model and its Subseasonal to Seasonal (S2S) precipitation forecast to ascertain its usefulness as a climate change adaptation tool over Nigeria. Observed daily and monthly CHIRPS reanalysis precipitation amount and the ECMWF subseasonal weekly precipitation forecast data for the period 1995–2015 was used. The forecast and observed precipitation were analyzed from May to September while El Nino and La Nina years were identified using the Oceanic Nino Index. Skill of the forecast was determined from standard metrics: Bias, Root Mean Square Error (RMSE), and Anomaly Correlation Coefficient (ACC).The Bias, RMSE, and ACC scores reveal that the ECMWF model is capable of predicting precipitation over Southern Nigeria, with the best skill at one week lead time and poorest skills at lead time of 4 weeks. Results also show that the model is more reliable during El Nino years than La-Nina. However, some improvement in the model by ECMWF can give better results and make this tool a more dependable tool for disaster risk preparedness, reduction and prevention of possible damages and losses from extreme rainfall during the wet season, thus enhancing climate change adaptation.
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Chimenti, Dale, Stanislav Rokhlin, and Peter Nagy. "Measurement of Scattering Coefficients." In Physical Ultrasonics of Composites. Oxford University Press, 2011. http://dx.doi.org/10.1093/oso/9780195079609.003.0012.
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In the previous chapters, we saw how waves in composites behaved under various circumstances, depending on material anisotropy and wave propagation direction. The most important function that describes guided wave propagation, and the plate elastic behavior on which propagation depends, is the reflection coefficient (RC) or transmission coefficient (TC). More generally, we can call either one simply, the scattering coefficient (SC). It is clear that the elastic properties of the composite are closely tied to the SC, and in turn the scattering coefficient determines the dispersion spectrum of the composite plate. Measuring the SC provides a route to the inference of the elastic properties. To measure the SC, we need only observe the reflected or transmitted ultrasonic field of the incident acoustic energy. In doing so, however, the scattered ultrasonic field is influenced by several factors, both intrinsic and extrinsic. Clearly, the scattered ultrasonic field of an incident acoustic beam falling on the plate from a surrounding or contacting fluid will be strongly influenced by the RC or TC of the plate material. The scattering coefficients are in turn dependent on the plate elastic properties and structural composition: fiber and matrix properties, fiber volume fraction, layup geometry, and perhaps other factors. These elements are not, however, the only ones to determine the amplitude and spatial distribution of energy in the scattered ultrasonic field. Extrinsic factors such as the finite transmitting and receiving transducers, their focal lengths, and their placement with respect to the sample under study can make contributions to the signal as important as the SC itself. Therefore, a systematic study of the role of the transducer is essential for a complete understanding and correct interpretation of acoustic signals in the scattered field. The interpretation of these signals leads ultimately to the inference of composite elastic properties. As we pointed out in Chapter 5, the near coincidence under some conditions of guided plate wave modes with the zeroes of the reflection coefficient (or peaks in the transmission coefficient) has been exploited many times to reveal the plate’s guided wave mode spectrum.
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Poply, Vikas. "Heat Transfer in a MHD Nanofluid Over a Stretching Sheet." In Heat Transfer - Design, Experimentation and Applications [Working Title]. IntechOpen, 2020. http://dx.doi.org/10.5772/intechopen.95387.
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The intention behind carrying out this research work is to analyze the heat transfer characteristics in a Magnetohydrodynamic (MHD) boundary layer nanofluid flow over a stretching sheet. Two phase representation of nanofluid studied the consequence of Brownian motion along with thermophoresis. The major purpose of study is to investigate the significant role of prominent fluid parameters thermophoresis, Brownian motion, Eckert number, Schmidt number and magnetic parameter on profile of velocity, temperature distribution and concentration. Runge–Kutta Fehlberg (RKF) method was adopted to numerically solve the non-linear governing equations and the linked boundary conditions by use of shooting technique. Over all the consequence of prominent fluid parameters are explained via graphs, whereas distinction of several valuable engineering quantities like skin friction coefficient, local Nusselt number and local Sherwood number are also tabulated. The finding of present study helps to control the rate of heat transportation as well as fluid velocity in any manufacturing processes and industrial applications to make desired quality of final product.
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Poply, Vikas. "Heat Transfer in a MHD Nanofluid Over a Stretching Sheet." In Heat Transfer - Design, Experimentation and Applications [Working Title]. IntechOpen, 2020. http://dx.doi.org/10.5772/intechopen.95387.
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The intention behind carrying out this research work is to analyze the heat transfer characteristics in a Magnetohydrodynamic (MHD) boundary layer nanofluid flow over a stretching sheet. Two phase representation of nanofluid studied the consequence of Brownian motion along with thermophoresis. The major purpose of study is to investigate the significant role of prominent fluid parameters thermophoresis, Brownian motion, Eckert number, Schmidt number and magnetic parameter on profile of velocity, temperature distribution and concentration. Runge–Kutta Fehlberg (RKF) method was adopted to numerically solve the non-linear governing equations and the linked boundary conditions by use of shooting technique. Over all the consequence of prominent fluid parameters are explained via graphs, whereas distinction of several valuable engineering quantities like skin friction coefficient, local Nusselt number and local Sherwood number are also tabulated. The finding of present study helps to control the rate of heat transportation as well as fluid velocity in any manufacturing processes and industrial applications to make desired quality of final product.
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Zhang, Weigang, Changming Xie, Xi Wei, and Min Ge. "C/C-ZrB2-ZrC-SiC Composite Derived from Polymeric Precursor Infiltration and Pyrolysis." In MAX Phases and Ultra-High Temperature Ceramics for Extreme Environments, 435–59. IGI Global, 2013. http://dx.doi.org/10.4018/978-1-4666-4066-5.ch014.
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Part II. Mechanical and ablation properties of the 2D C/C-ZrB2-ZrC-SiC composites with a fiber volume fraction of 17.6%, fabricated by infiltration and co-pyrolysis of blended polymeric precursors, were studied in this Part II. Flexural strength and fracture toughness of the composites were found to be influenced strongly by the thickness of the deposited pyrolytic carbon interphase, a composite with the pyrolytic carbon volume fraction of 22.3% exhibits improved bending strength and fracture toughness of 127.9 MPa and 6.23 MPa·m1/2, respectively. The pseudo-plastic strain to failure of the composite is ascribed to sliding of the interphase and pulling out of carbon fibers from the brittle ceramics matrix. Ablation properties of the composite were investigated with a plasma torch and arc-heated wind tunnel tests at temperatures above 1800~2200°C. The composite exhibits very low ablation rates of 0.18×10-3 mm/s at 1800°C and 0.37×10-3 mm/s at 2000°C in the plasma torch after 1000s testing, as compared to a similar rate of 0.30×10-3 mm/s in the wind tunnel at 1900°C after 600s testing. Ablation rates increase with increasing of temperatures from 1800 to 2200°C. The maximum ablation rate is only 1.67×10-3 mm/s in a plasma torch at 2200°C for 1000s, decreased by 71.0% as compared with the C/C-SiC composite with the same fiber and interphase contents. The 2D C/C-ZrB2-ZrC-SiC composite simultaneously showed excellent thermal shock resistance, on account of no cracks on the surface and breakage of the material being detected after these abrupt temperature increasing and long time ablations. The heating-up rate at the center of the composite specimen was found as high as above 30K/s in the plasma torch tests. Excellent ablation and thermal shock resistances of the composite can be attributed to its architecture of carbon fiber and interphase, as well as its matrix microstructures characterized by nano sized dispersions of ZrB2-Zr-SiC phases inherent formed by co-pyrolysis of three polymeric precursors. These meso- and microstructures make the composites possess very small and steady coefficients of thermal expansion (CTE) around 1.5~2.5×10-6/K and high thermal conductivities around 10~14 W/mK (which increases with increasing of temperature) from room temperature to 1300°C, respectively. Surface products and cross sectional morphologies of the composite after the ablation tests were also investigated using SEM and XRD, it was found that a homogeneous distributed and continuous glass layer composing of ZrO2-SiO2 with zirconia as a skeleton was in-situ formed. These special features of coating benefits from the merits of matrix microstructures, and inhibits the inward diffusion of oxygen and protects the composite from further oxidation and spalled off by strong gas fluid.
Conference papers on the topic "Make-out coefficient"
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Kobus, Chris J. "Indirectly Measuring the Convective Heat Transfer Coefficient Utilizing Thermistors for Education and Research." In ASME 2013 Heat Transfer Summer Conference collocated with the ASME 2013 7th International Conference on Energy Sustainability and the ASME 2013 11th International Conference on Fuel Cell Science, Engineering and Technology. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/ht2013-17098.
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A primary parameter of interest in many heat transfer problems is the convective heat transfer coefficient, which is dependent upon several fundamental parameters like fluid properties, velocity, temperature distribution, etc. As such, empirically determining this parameter can be complicated, especially in educational settings. The classical method includes many physical temperature sensors and heating pads distributed throughout a body that necessitates complex control schemes and data acquisition systems. This paper details a far simpler method of indirectly measuring the convective heat transfer coefficient by utilizing thermistors of various geometries. In calibrating these thermistors for their temperature-resistance characteristics, the convective heat transfer coefficient can be backed out without directly measuring the temperature of the thermistror itself, which has the effect of simplifying the experimental requirements to a large enough degree to make the technique suitable for introductory educational courses in heat transfer. In addition, the technique is also accurate enough to where the experimental data is worthy of publication in the archival literature.
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Zhang, Chenyun, Yong Huang, Xin Zhao, and Jinlun Cai. "Sensitivity data driven optimal design for steel frame tall buildings." In IABSE Congress, Ghent 2021: Structural Engineering for Future Societal Needs. Zurich, Switzerland: International Association for Bridge and Structural Engineering (IABSE), 2021. http://dx.doi.org/10.2749/ghent.2021.1931.
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<p>Structural design generally involves hundreds of design variables and multiple constraints in practical engineering projects, nevertheless, traditional optimization techniques are failed to meet the engineering requirements for solving the optimization problem with high efficiency and accuracy. In this paper, a single driven constraint optimization method based on constraint sensitivity is presented for high-rise steel structure. The design method takes the sensitivity coefficient as the reference index for the optimization design of components to ensure proper compliance and redundancy requirements. An effective incremental analysis method is applied for the calculation of sensitivity coefficients within constraints and design variables. Sensitivity coefficients based material redistribution of components is carried out to make the structure achieve the optimization objective on the premise of satisfying all the design constraints.</p>
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Zhang, Chenyun, Yong Huang, Xin Zhao, and Jinlun Cai. "Sensitivity data driven optimal design for steel frame tall buildings." In IABSE Congress, Ghent 2021: Structural Engineering for Future Societal Needs. Zurich, Switzerland: International Association for Bridge and Structural Engineering (IABSE), 2021. http://dx.doi.org/10.2749/ghent.2021.1931.
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<p>Structural design generally involves hundreds of design variables and multiple constraints in practical engineering projects, nevertheless, traditional optimization techniques are failed to meet the engineering requirements for solving the optimization problem with high efficiency and accuracy. In this paper, a single driven constraint optimization method based on constraint sensitivity is presented for high-rise steel structure. The design method takes the sensitivity coefficient as the reference index for the optimization design of components to ensure proper compliance and redundancy requirements. An effective incremental analysis method is applied for the calculation of sensitivity coefficients within constraints and design variables. Sensitivity coefficients based material redistribution of components is carried out to make the structure achieve the optimization objective on the premise of satisfying all the design constraints.</p>
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Zhao, Peng, and Tadaatsu Satomi. "Study on Aerostatic Guidance: Discussion of Flux Coefficients of Orifice." In ASME 2005 International Mechanical Engineering Congress and Exposition. ASMEDC, 2005. http://dx.doi.org/10.1115/imece2005-80671.
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In recent years the aerostatic guidance has been used as a precision positioning apparatus in the Integrated Circuit manufacturing or bioengineering field. The purpose of this study is to examine the relationship between the squeeze part of aerostatic guidance and the mass flux, and to make the theoretical calculation on the aerostatic guidance more accurate, when designing an aerostatic guidance. In this study we produced a measurement device to obtain the flux characteristics of the compressed air passing through an orifice with 0.4mm diameter. We used this measurement device to obtain the flux coefficient of the orifice where the air is blowing out in a direction vertical to the guidance surface. The pressure distribution of the guidance surface was measured and the static load characteristic experiment was carried out. Then the experiment values obtained thereby were compared with theoretical values. The results show that although the flux coefficient could be dealt with a fixed value in the region of orifice-squeeze1) when the flux coefficient was calculated from the flux characteristics, it was no longer a fixed value in the region of self-squeeze1). This is considered a cause of the remarkable error in the above-mentioned design calculation result. Thus, in this study the influence of the inner surface roughness (of the orifice) affecting the flux characteristics was clarified and a novel flux formula, where the flow in the boundary layer is taken into account, is devised and formed. As a result, we have established an improved design scheme and theory by which the theoretical computation on the aerostatic guidance can be performed with more sufficient accuracy.
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Ye, Lin, Cun-liang Liu, Hui-ren Zhu, Jian-xia Luo, and Ying-ni Zhai. "Investigations on the Influence of Rib Orientation Angle on Film Cooling Performance of Cylindrical Holes." In ASME Turbo Expo 2017: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/gt2017-63968.
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This paper presents an experimental and numerical investigation on the film cooling with different coolant feeding channel structures. Two ribbed cross-flow channels with rib-orientation of 135° and 45° respectively and the plenum coolant channel have been studied and compared to find out the effect of rib orientation on the film cooling performances of cylindrical holes. The film cooling effectiveness and heat transfer coefficient were measured by the transient heat transfer measurement technique with narrow-band thermochromic liquid crystal. Numerical simulations with realizable k-ε turbulence model were also performed to analyze the flow mechanism. The results show that the coolant channel structure has a notable effect on the flow structure of film jet which is the most significant mechanism affecting the film cooling performance. Generally, film cooling cases fed with ribbed cross-flow channels have asymmetric counter-rotating vortex structures and related asymmetric temperature distributions, which make the film cooling effectiveness and the heat transfer coefficient distributions asymmetric to the hole centerline. The discharge coefficient of the 45° rib case is the lowest among the three cases under all the blowing ratios. And the plenum case has higher discharge coefficient than the 135° rib case under low blowing ratio. With the increase of blowing ratio, the discharge coefficient of the 135° rib case gets larger than the plenum case gradually, because the vortex in the upper half region of the coolant channel rotates in the same direction with the film hole inclination direction and makes the jet easy to flow into the film hole in the 135° rib case.
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Liu, Cun-liang, Hui-ren Zhu, Jiang-tao Bai, and Du-chun Xu. "Film Cooling Performance of Waist-Shaped Slot Holes." In ASME Turbo Expo 2010: Power for Land, Sea, and Air. ASMEDC, 2010. http://dx.doi.org/10.1115/gt2010-22237.
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Film cooling performance of a new shaped hole: waist-shaped slot hole is studied in this paper. Experimental measurement and numerical simulation are carried out to investigate the film cooling character and physics of this new shaped hole. And comparisons between the waist-shaped slot hole and two kinds of console holes are also performed. Both the cooling effectiveness distribution and the heat transfer coefficient distribution of the waist-shaped slot hole are similar with those of the console hole with large divergence angle because of the effect of the waist-shaped slot hole’s structure. The middle constriction structure of the waist-shaped slot hole and the coupled vortices make jets from the waist-shaped slot holes produce higher cooling effectiveness in the midspan region between adjacent holes. And also due to the effect of the middle constriction structure, the heat transfer coefficient of the waist-shaped slot hole is very high in the upstream midspan region. However, the heat transfer coefficient in the downstream midspan region is lower than that in the region near the hole centerline because of the effect of the coupled vortices. The waist-shaped slot holes provide the surface with very good thermal protection, especially in the upstream region. Although the console holes with small exit-entry area ratio provide better thermal protection than the waist-shaped slot holes due to small turbulence intensity, the flow resistance characteristic of the waist-shaped slot hole is much better.
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Li, Jingjing, Tao Zhou, Mingqiang Song, and Yanping Huang. "The Research of Flow Instability in Vertical Parallel Natural Circulation Channels Based on Relap5." In 2013 21st International Conference on Nuclear Engineering. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/icone21-15686.
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The gas-liquid two phase flow oscillation in vertical parallel natural circulation channels was performed by the best estimate system computer code Relap5. The effects of symmetry and dissymmetry degree of heated power to flow oscillation and the effects of symmetry and dissymmetry throttling to flow oscillation were researched. The results says that when the twin channels under the same conditions of geometry and boundary, the parameters of the twin channel such as flow are the same. So under these conditions the twin channels can be researched as single channel. It is more possible of flow oscillation for the channels under condition of dissymmetry heating. The use of throttling will make the channels more stable, it is more stable when the throttling coefficient increases. With the implement of dissymmetry throttling, the system is possible for out of phase flow oscillation.
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Liu, Cong, and Hui Liu. "Coordinated Control of AFS and DYC for 4WID-EVS Handling and Stability Based on Driving State Prediction." In FISITA World Congress 2021. FISITA, 2021. http://dx.doi.org/10.46720/f2020-vdc-042.
Full textAbstract:
Considering that the driver's response was not timely under extreme conditions, and there was a time delay between the driver's behavior and the actuator, which would destabilize the vehicle. A coordinated control strategy based on driving state prediction was designed for improving 4WID-EVS lateral stability and handling performance through direct yaw moment control system (DYC) and active front steering (AFS). Firstly, the coordinated control strategy of AFS and DYC was designed, which consisted of two parts: (1) A stability judgeing method based on sideslip angle and sideslip angular velocity phase plane was proposed. The phase plane stability boundary coefficient was adjusted by the road adhesion coefficient, which divided the coordination control region reasonably, so as to judge whether the vehicle was unstable and switched the appropriate subsystem. (2) A driving state prediction algorithm based on data stream mining technology and Markov theory was proposed. The fuzzy control theory which had good robustness was applied, the driving state in the future were made as the inputs, which could determine the weight coefficients of AFS and DYC in advance and effectively avoid the potential danger of entering the unstable state. Secondly, the nonlinear 3-dof vehicle model was used as the reference model, and AFS control strategy was designed based on model predictive control (MPC) theory. At the same time, in order to avoid no solution in the calculation process and improve the convergence speed of the solution process, the relaxation factor was introduced. The quadratic programming algorithm was adopted to find the optimal solution, so as to adjust the front wheel angle in real time to follow the desired path. In order to make up for the deficiency of AFS control strategy, the feedforward - feedback DYC control strategy was designed. A variable weight coefficient LQR feedback control strategy was proposed, and the matrix weight coefficient could be adjusted in real time according to the vehicle steering state in the future and the road adhesion coefficient at the present. Finally, the accuracy and real-time of the prediction algorithm were verified according to different and actual driving cycle data. The simulation experiments of typical working conditions were carried out based on commercial dynamics simulation software to verify the effectiveness of the coordinated control strategy. The simulation results showed that the coordinated control method of AFS and DYC proposed had better effect of driving stability control, which provided a new method for the design of vehicle active safety. KEY WORDS: distributed drive, coordination control, data stream mining, Markov, MPC
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Roulo, David, Zachary Ptasienski, Brandon McCumber, and Subha Kumpaty. "NASCAR Truck Aerodynamic Analysis and Improvement." In ASME 2017 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/imece2017-70138.
Full textAbstract:
The NASCAR Truck Aerodynamic Improvement team is tasked with providing aerodynamic analysis and improvement to Ford Performance and their factory supported team Brad Keselowski Racing for their Ford F-150 race trucks. A Ford F-150 race truck is a “stock” truck that has some modifications for racing speed and safety. Ford Performance, reached out to an MSOE student and asked if a Senior Design team and project could be assembled to provide them with some aerodynamic analysis and improvements that would not require them to build and test using a trial-and-error type method resulting in expensive, and real, testing. The purpose of this project was to conduct a computational fluid dynamic analysis on the truck and make design changes to the truck that will provide more down force on the front two tires. The areas of the truck that were studied included the side panels, deck lid, rear quarter panels, and frontal geometry. There were also constraints put in place by the NASCAR rulebook on the vehicle specifications. These rules limit the design changes that were made to the truck. The model was originally sent as a laser scanned STL file. This file needed to be heavily edited in order to be imported into the CFD program. The programs used to edit this file include Geomagic, Autodesk Fusion 360, and SolidWorks. Through using these programs, the laser scan file was modified to a usable format. Upon conclusion of the CFD simulations using ANSYS Fluent, it was found that the truck with no geometry changes displayed a drag coefficient of 0.489 and a lift coefficient of −0.815. These results were found after 10,000 iterations of testing. The standard deviation in the drag and lift coefficients were 0.00743 and 0.01660 respectively. All statistical calculations along with the averaged solutions were calculated using the data after the 2,500th iteration. This is because the nature of the CFD solutions tend to fluctuate greatly at first and then slowly converge with more iterations. After the 2,500th iteration, a relatively steady state in the solutions is met where the residuals are converging to a single value or the fluctuation in the solutions is repetitive. The following design changes were made in attempt to increase the down force on the truck. A rib was added to the side panel in order to increase the downforce on the truck. The side panel was also modified with a cut. The contour on the rear deck lid was smoothed in order to decrease drag on the truck. Slots were cut out of the shell of the truck behind the rear wheels on both sides of the truck. These slots were angled in an attempt to create down force on the rear wheels. The front splitter was lowered closer to the ground in attempt to increase air velocity moving under the truck. This higher velocity air would create a lower pressure region under the car which would increase down force. All of these modifications were applied to the initial truck body and tested using the same setup as the baseline. The most successful design change was the rear deck lid modification which resulted in a drag coefficient of 0.472 and a lift coefficient of −0.816. This is a 3.48% decrease in the drag coefficient and a 0.12% decrease in the lift coefficient (or 0.12% increase in downforce). The results of this project were purely simulation based; any real modifications and field testing made will be performed by Brad Keselowski Racing and Ford Performance.
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Pazzi, Simone, Francesco Martelli, Marco Giachi, and Michela Testa. "Application of a CFD-Based Program for the Optimization of a Centrifugal Impeller." In ASME 2003 International Mechanical Engineering Congress and Exposition. ASMEDC, 2003. http://dx.doi.org/10.1115/imece2003-55220.
Full textAbstract:
A typical centrifugal impeller characterized by a low flow coefficient and cylindrical blades is redesigned by means of an intelligent automatic search program. The procedure consists of a Feasible Sequential Quadratic Programming (FSQP) algorithm [6] coupled to a Lazy Learning (LL) interpolator [1] to speed-up the process. The program is able to handle geometrical constraints to reduce the computational effort devoted to the analysis of non-physical configurations. The objective function evaluator is an in-house developed structured CFD code. The LL approximator is called each time the stored database can provide a sufficiently accurate performance estimate for a given geometry, thus reducing the effective CFD computations. The impeller is represented by 25 geometrical parameters describing the vane in the meridional and s-θ planes, the blade thickness and the leading edge shape. The optimisation is carried out on the impeller design point maximizing the polytropic efficiency with more or less constant flow coefficient and polytropic head. The optimization is accomplished keeping unaltered those geometrical parameters which have to be kept fixed in order to make the impeller fit the original stage. The optimisation, carried out on a cluster of sixteen PCs, is self-learning and leads to a geometry presenting an increased design point efficiency. The program is completely general and can be applied to any component which can be described by a finite number of geometrical parameters and computed by any numerical instrument to provide performance indices. The work presented in this paper has been developed inside the METHOD EC funded project for the implementation of new technologies for optimisation of centrifugal compressors.