Wang Model Research Articles

Общая классификация потерь и обзор моделей вторичных течений в решетках газовых турбин

Much attention is paid to increasing the efficiency of turbofan engines by increasing the efficiency of the main modules. The aerodynamic efficiency of a turbine depends on the level of total pressure and kinetic energy losses, which are determined by the scale of secondary flows in the channels of the turbine cascades. There are many studies and articles on the topic of secondary flows, in which vortex structures are often given incorrect names. The problem lies in the absence of a unified model of secondary flows and mismatch in the names of the components of secondary flows in adaptation of model descriptions from English to Russian. The purpose of this review article is to consider the existing classifications of losses and the most famous models of secondary flows in turbine cascades, including the Wang model, the Goldstein and Spores model, the Sharma and Butler model, etc. The considered sources of information made it possible to single out the most complete classification of losses, compare with each other the components of secondary flows of various models, describe the mechanism of their occurrence and give the most complete nomenclature of secondary flows in turbine cascades.

Study on Permeability Anisotropy of Bedded Coal Under True Triaxial Stress and Its Application

Anisotropy is a very typical observation in the intrinsic bedding structure of coal. To study the influence of anisotropy of coal structure and stress state on the evolution of permeability, a newly developed multifunctional true triaxial geophysical apparatus was used to carry out mechanical and seepage experiments on bedded coal. The permeability and deformation of three orthogonal directions in cubic coal samples were collected under true triaxial stress. It has detected the significant permeability anisotropy, and the anisotropy is firmly determined by the bedding direction and stress state of coal. Based on the true triaxial mechanical and seepage test results, the coal with bedding was simplified to be represented by a cubic model, and the dynamic anisotropic (D-A) permeability model was derived by considering the influence of bedding and stress state. The rationality of the permeability model was verified by the experimental data. Comparing the permeability model with Wang and Zang (W–Z) model, Cui and Bustin (C–B) model and Shi and Durucan (S–D) model, it is found that the theoretical calculated values of the D-A permeability model are in better agreement with the experimental measured values, reflecting the superiority of the D-A permeability model. Based on incorporating the model of D-A permeability under the concept of multiphysics field coupling, the numerical simulation experiments of coal seam gas extraction with different initial permeability anisotropic ratios were carried out by using COMSOL multiphysics simulator. The influence of initial permeability anisotropy ratio on gas pressure distribution in coal seam during gas extraction was explored, which provides theoretical guidance for the optimization of borehole layout for gas extraction in coal mine.

SMOS brightness temperature forward modelling and long term monitoring at ECMWF

This paper presents the forward modelling aspects of the SMOS (Soil Moisture and Ocean Salinity) activities at ECMWF (European Centre for Medium-Range Weather Forecasts). Several parameterizations of the Community Microwave Emission Modelling Platform (CMEM) are used to simulate L-band Brightness Temperatures (TBs) and compared to the SMOS TBs for 2010–2011. We show that simulated TBs are primarily sensitive, by order of importance, to the soil roughness model, the vegetation opacity and the soil dielectric model. In particular, best CMEM results are obtained with the simple Wigneron soil roughness model and the Wigneron model for the vegetation opacity. For the soil dielectric model, performances of the Wang and Schmugge and the Mironov models are shown to be similar and better than the Dobson model. The Wang and Schmugge model is then used in the next steps of this paper combined with the Wigneron roughness and vegetation models. The paper describes a multi-angular multi-polarised bias correction method based on a linear rescaling (mean and variance) computed at the monthly scale using SMOS observations and ECMWF-CMEM re-analysed TBs for a four year period (2010–2013). Results show that for 2010–2013 the seasonal multi-angular multi-polarisation bias correction approach reduces global RMSE to 7.91 K, compared to 16.7 K before bias correction, whereas the mean absolute bias is reduced to 1.39 K, compared to 11.04 K before bias correction. The consistency between the seasonality of simulated and the observed TBs is also improved by using a monthly bias correction, leading to correlation values improvement to 0.62 after bias correction compared to 0.56 before. The 2010–2013 bias correction applied to the 2014–2016 period at 40° incidence reduces the global RMSE from 15.56 K to 8.19 K, and the mean absolute bias from 10.16 K to 2.51 K, with no impact on the correlation values that remain at 0.61 in both cases. Long term monitoring of SMOS TB is presented covering a 7-year period (2010–2016) at both polarisations, at 40° incidence angle. Results show that the consistency between SMOS and ECMWF reanalysis-based TBs progressively improved between 2010 and 2016, pointing out improvements of level 1 SMOS TB products quality through the SMOS lifetime.

Meshfree investigation of the vibrational behavior of pre-stressed laminated composite plates based on a variationally consistent plate model

The vibrational behavior of pre-stressed laminated composite plates is numerically investigated based on a variationally consistent shear deformation plate theory. The numerical analyses are performed by the use of meshfree radial point interpolation method (RPIM). The plate model utilized in this investigation is the Wang and Shi's [1] plate theory which accounts for continuity of interlaminar transverse shearing stresses and zigzag variation of displacement field through the plate's thickness. Firstly, the governing equations for the free vibration of pre-stressed laminated and sandwich plates based on the Wang and Shi's model are derived through the Hamilton's principle. Subsequently, the weak-form of the governing equations is obtained, and the meshfree RPIM is utilized for construction of the discretized system of equations. Several numerical examples with different Young's modulus ratios, side to thickness ratios, boundary conditions, and lamination schemes are presented in order to illustrate the accuracy of the plate theory adopted in this paper. These examples are also analyzed using the first order shear deformation theory (FSDT), the third order shear deformation theory (TSDT), and also the Shi's [2] plate theory in order to investigate the effect of different factors of plate theories on the accuracy of results in various situations.

Building Readiness and Intention Towards STEM Fields of Study: Using HSLS:09 and SEM to Examine This Complex Process among High School Students

ABSTRACT Building on Social Cognitive Career Theory and Xueli Wang's conceptual model of STEM choice, this study advances and tests a model seeking to understand STEM readiness and intention to pursue STEM fields among a representative national sample of 9th grade students drawn from the High School Longitudinal Study of 2009. Structural equation model results suggest several contextual influences (e.g., personal characteristics) and social-cognitive variables (e.g., math and science self-efficacy) contributing to building STEM readiness and students’ intention to major in STEM during high school. In general, STEM readiness is impacted directly by SES, math ability, parental involvement, math self-efficacy, science self-efficacy, math interest, and science interest. Intention to major in STEM is directly impacted by STEM readiness, as well as high school students’ interest in math and interest in science. Overall, this study expands our knowledge of the process that leads high school students to become prepared for and aspire to pursue majors in STEM.

Experimental Study of Drying Characteristics and Mathematical Modeling for Air Drying of Germinated Brown Rice

In view of existing problems in the drying process of germinated brown rice (GBR), the self-made hot air drying test system was utilized. The drying medium temperature and wind speed were selected as the drying parameters, and different constraints were set for the test. The effects of the drying medium temperature and wind speed on the drying rate and unit energy consumption were examined, and the drying mathematical models of GBR were established. The results perceived that as the temperature rose, and the wind speed increased, the drying rate increased accordingly. When the temperature was above 95°C, wind speed exceeded 3.6 m/s; the drying rate would not change deliberately. When the temperature of the drying medium rose, the change rate during the drying preheating stage and the deceleration stage increased sharply, whereas the drying rate in the constant-speed drying stage increased, and the drying time was greatly shortened. Unit energy consumption decreased with the increase of temperature and increased with increasing wind speed. Furthermore, when the drying temperature was ranged between 50°C and 80°C, the unit energy consumption changed meaningfully; when the medium temperature was between 80°C and 110°C, the unit heat consumption turned slowly. Wang and Singh’s model could best simulate the drying process of GBR within the experimental settings. And then comparing the RMSE and under the various dry conditions, the data of Wang and Singh model were between 1.6% - 2.8% and 2.5×10-4 - 5×10-4. The R2 values of the model were higher than 0.98.

Seismic Fragility Analysis of Buildings Based on Double-Parameter Damage Models considering Soil-Structure Interaction

Most conventional seismic fragility analyses of RC buildings usually ignore or greatly simplify the soil-structure interaction (SSI), and the maximum interstory drift ratio (MIDR) is often adopted to establish seismic fragility curves. In this work, an eight-story RC building was designed to study the influence of the SSI on the seismic fragility of RC buildings. Three double-parameter damage models (DPDMs) were considered for the fragility assessment: the Park–Ang model, the Niu model, and the Lu–Wang model. Results show that considering SSI induces a higher fragility than that of the fixed model and that employing the DPDMs for the fragility analysis provides more reasonable results than those evaluated using the MIDR damage index.

The Experimental Research of Drying Kinetics of Nagpur Orange Fruit (Citrus Sinesis- L) by Hot Air Electrical Dryer

The study is aimed experimentally and compared with the theoretical results of drying kinetics of Nagpur orange fruit dried in a hot air electrical dryer. Orange fruit is highly perishable and needs to be consumed or processed immediately after harvest. Drying or dehydration is one of the most practical methods of preserving food products. Therefore, thin layer drying characteristics of falling rate of Nagpur orange are determined experimentally under different conditions of drying air temperatures, relative humidity and air velocities for different moisture contents. Thin layer models like Wang and Singh, Page and Henderson have been compared with Experimental results. The knowledge of drying kinetics helps for identification of exact drying time and air flow velocity for different moisture content. Here drying operation is carried out at a velocity of 1m/sec and 1.25 m/sec for different temperature of 55°C, 65°C and 75°C. This analysis reveals that drying temperature has a more significant effect on moisture removal while velocity has the least effect. Drying rate is found to increase with the increase in drying temperature and reduce with drying time. Experimental data is statistically correlated by plotting the drying characteristics curve. The analysis reveals that Wang and Singh's model is a better model to explain the drying behavior of Nagpur Orange fruit (R2=0.9888).

Interval-valued fuzzy multi-criteria decision-making based on simple additive weighting and relative preference relation

To encompass imprecise messages, traditional multi-criteria decision-making (MCDM) was generalized into fuzzy multi-criteria decision-making(FMCDM) in solving decision-making problems. In numerous MCDM methods, simple additive weighting(SAW) is the simplest one, but fuzzy multiplication for generalizing SAW under fuzzy environment is still complicated, especially interval-valued fuzzy numbers. In the past, Wang proposed a model based on SAW and relative preference relation to resolve fuzzy multiplication tie. Practically, Wang's model is useful to fuzzy generalization of SAW. However, the model is only used in triangular fuzzy numbers. Recently, more and varied messages are obtained and processed for decision-making problems. Triangular fuzzy numbers are insufficient to express the variance, whereas interval-valued fuzzy numbers are suitable. Therefore, SAW had to be generalized under interval-valued fuzzy environment. In this paper, we combine SAW with a relative preference relation into interval-valued FMCDM to avoid fuzzy multiplication and grasp more messages. Our proposed relative preference relation improved from Lee's fuzzy preference relation is similar to Wang's relative preference relation. The main difference is that the proposed relation is utilized in interval-valued fuzzy numbers, whereas Wang's is used in triangular fuzzy numbers. To sum up, we provide the FMCDM to solve decision-making problems with interval-valued fuzzy numbers easily and quickly.

Multilingual students’ use of their linguistic repertoires while writing in L2 English

This article examines six multilingual students’ composing processes and language use while writing in L2 English. Four participants have two L1s: Swedish and either Bosnian (N=2) or Macedonian (N=2). The remaining two participants have Swedish as their L1. Building on an L2 composing model (Wang and Wen, 2002) and the theory of Language Mode (Grosjean, 2008), the study uses think-aloud data to examine participants’ use of their language repertoires while writing an essay in L2 English. Think-aloud data revealed that Swedish served as the base language of thought for four of the participants. The other two participants used mainly English and for a greater range of composing activities. Bosnian, a heritage language for two of the participants, was used by one participant for context-specific idea-generation. The results suggest that multilinguals rely on their L1s vis-a-vis the target language for specific purposes when working individually on a complex task such as L2 writing. An elaboration of the Wang and Wen (2002) model revealed that English was used mainly to read the text being produced, whereas Swedish was used to comment on the writing process, to solve problems and to have an inner dialogue.

DRYING KINETICS OF THE SLICED PULP OF BIOFORTIFIED SWEET POTATO (Ipomoea batatas L.)

ABSTRACT Biofortified sweet potato (Ipomoea batatas) is one of the foods with the highest contributions of carotenoids in the diet, especially provitamin A carotenoids. Thus, this study aimed to analyze the drying kinetics of the biofortified sweet potato pulp using the Akaike (AIC) and Schwarz's Bayesian (BIC) information criteria for model selection, as well as determine the effective diffusion coefficient and activation energy under different drying conditions. The biofortified sweet potatoes were sliced into chips and submitted to drying in an air circulation oven at 1.0 m s−1 at temperatures of 45, 55, 65, and 75 °C until constant mass. The mathematical models Wang and Singh, Verma, Thompson, Page, Newton, Midilli et al., logarithmic, Henderson and Pabis, two-term exponential, two-term, diffusion approach, frequently used to predict the drying of vegetal products, were adjusted to the data. The Wang and Singh model was selected to represent the drying of the biofortified sweet potato pulp by exhibiting the best adjustment for most conditions. The AIC and BIC criteria were suitable for selecting the Wang and Singh model. The effective diffusion coefficient increased as drying air temperature increase and the activation energy for liquid diffusion was 29.18 kJ mol−1.

Micromechanical Modelling of the Cyclic Deformation Behavior of Martensitic SAE 4150—A Comparison of Different Kinematic Hardening Models

A fundamental prerequisite for the micromechanical simulation of fatigue is the appropriate modelling of the effective cyclic properties of the considered material. Therefore, kinematic hardening formulations on the slip system level are of crucial importance due to their fundamental relevance in cyclic material modelling. The focus of this study is the comparison of three different kinematic hardening models (Armstrong Frederick, Chaboche, and Ohno–Wang). In this work, investigations are performed on the modelling and prediction of the cyclic stress-strain behavior of the martensitic high-strength steel SAE 4150 for two different total strain ratios (R ε = −1 and R ε = 0). In the first step, a three-dimensional martensitic microstructure model is developed by using multiscale Voronoi tessellations. Based on this martensitic representative volume element, micromechanical simulations are performed by a crystal plasticity finite element model. For the constitutive model calibration, a new multi-objective calibration procedure incorporating a sensitivity analysis as well as an evolutionary algorithm is presented. The numerical results of different kinematic hardening models are compared to experimental data with respect to the appropriate modelling of the Bauschinger effect and the mean stress relaxation behavior at R ε = 0. It is concluded that the Ohno–Wang model is superior to the Armstrong Frederick and Chaboche kinematic hardening model at R ε = −1 as well as at R ε = 0.

Modeling and simulation of moisture transfer during solar drying of carrot slices

AbstractCarrot slices of 0.03 m diameter and 0.005 m thickness were dried in direct, indirect and mixed mode type natural convection solar dryers. Thin layer drying behavior of carrot slices was studied using 10 empirical and semi‐empirical mathematical models. Wang and Singh model described the drying behavior of carrot accurately with maximum values of coefficient of determination (R2) and minimum reduced chi‐square (χ2), and root mean square error (RMSE). The effective diffusivity (Deff) and convective mass transfer coefficient (hm) of carrot slices ranged from 2.59 × 10−8−6.36 × 10−8 m2/s and 3.15 × 10−7 to 4.28 × 10−7 m/s, respectively, with maximum values obtained for mixed mode solar dried samples followed by direct and indirect solar dried samples. The diffusivity of carrot slices dried in direct, indirect and mixed‐mode solar dryer were expressed as a function of temperature using Arrhenius relation. Finite element model was developed using COMSOL Multiphysics software to simulate moisture ratio during drying. The developed model predicted the transient moisture migration phenomenon inside the samples precisely during the drying process.Practical applicationsThe ever increasing worriment on climate change and growing demand for enactment of clean energy technologies in food industries is the motivation for investigating the solar drying behavior of carrot slices. It is well known that the physico‐chemical and sensorial changes during drying are very much dependent on the moisture content of food product. In this regard, proper understanding and controlling of the solar drying process by accurately predicting moisture distribution inside the product will result in superior quality dried products. Moreover, mathematical models will assist in predicting the drying behavior of food product by analyzing the influence of process parameters and will be helpful to minimize the cost of drying process and deterioration of quality attributes of the product. The use of solar dryers is a proven technology and the food industry should promote its practical applications in food processing sector.

Development and Validation of the Chinese Modesty Scale (CMS).

This paper describes the development and method of validation of the Chinese Modesty Scale (CMS). Based on Wang’s dualistic model for value and instrumental modesty, our study employed a review of the literature, in-depth interviews, open-ended investigations, and feedback from experts. An initial 14-item scale for analyzing the issue of “Chinese modesty” was developed. Then we explored the dimensions and final items of this CMS using item analysis and exploratory factor analysis (EFA) with sample 1 (n = 406). After that, we conducted a confirmatory factor analysis (CFA) to replicate the factor structure obtained through EFA with a refined, independent, 12-item scale (n = 662). Results confirmed the dualistic model (for value and instrumental modesty) on which this scale was based. That is, we found that there are two kinds of “Chinese modesty”: value modesty and instrumental modesty. As a valid, reliable scale, the CMS can therefore be used to measure the “Chinese modesty” of/in different age groups.

Effectiveness of recyclable aluminum cans in fabricating an efficient solar collector for drying agricultural products

Abstract The shortages in conventional fuels along with the continuous rise in their prices have led to an increased emphasis on using solar energy as an alternative source of energy. However, establishing reliable and affordable solar collectors for different applications is a great challenge. Therefore, this study aimed to design and fabricate an efficient and cheap solar air collector from recyclable aluminum cans. Two dryers of different configurations (closed and open modes) were then constructed and examined for drying tomatoes under different operating conditions. The results revealed that the thermal efficiency of the designed solar collectors increased considerably from 25 to 63% when the air-flow rate increased from 15 to 45 m3h-1. In comparison to the conventional method of open sun drying, the designed solar dryers enhanced both the drying rate and the overall quality of the final product. In the designed solar dryer, over three days of consecutive drying (30 h of drying), the moisture content of tomato wedges was reduced from 19 to less than 1 kg [H2O] kg−1 [dry matter]. The closed-mode dryer configuration, which recirculates the drying air, showed a considerable increase in the drying rate and weigh loss over the traditional sun dryers and open-mode dryer systems. Among all mathematical models, a non-linear quadratic model (Wang and Singh model) has shown a better fit to the experimental drying data compared to the other models.

Ecuaciones generalizadas altura-diámetro para bosques de Pinus pseudostrobus Lindl. en Nuevo San Juan Parangaricutiro, Michoacán, México

La estimación precisa de la altura total de los árboles es fundamental para el manejo forestal, pero la medición de todos los individuos en un inventario es prácticamente imposible por los tiempos y costos que genera. El objetivo de este trabajo fue ajustar una ecuación generalizada que estime la altura total como una función del diámetro normal (h-d) para bosques de Pinus pseudostrobus Lindl., en la comunidad indígena de Nuevo San Juan Parangaricutiro, Michoacán. Con datos de 158 sitios de inventario forestal, se ajustaron 12 modelos generalizados de h-d. El modelo de Wang y Tang, que incluye el diámetro normal y la altura media dominante, fue el mejor por presentar parámetros significativos, los mínimos valores del cuadrado medio del error, la raíz del cuadrado medio del error y el coeficiente de determinación ajustado. El análisis de puntos de influencia de los residuales estudentizados varió entre 2.5 y -2.5, mientras que la distancia de Cook no mostró problemas. La distribución de residuales fue homocedástica, el valor en la prueba de Durbin-Watson fue de 1.7 y la prueba de Shapiro-Wilk de 0.97. El índice de curtosis fue de -2.35 y la tendencia en la campana de Gauss fue leptocúrtica. El sesgo fue de 0.004 m y la diferencia agregada fue de -0.017%. El modelo seleccionado resultó confiable al estimar la altura total hasta los 60 cm de diámetro y se puede ser empleado en los inventarios forestales para la especie.

Impact of angular deviation from coincidence site lattice grain boundaries on hydrogen segregation and diffusion in α-iron

Abstract

Modeling of drying and ameliorative effects of relative humidity (RH) against β-carotene degradation and color of carrot (Daucus carota var.) slices.

Drying and β-carotenes retention kinetics were predicted using models in relative humidity (RH) drying condition. This was achieved by drying carrot slices using RH-convective hot-air dryer at 60, 70 and 80°C under RH (10% 20% and 30%) conditions at 2.0m/s air velocity. Three mathematical models describing thin layer were compared to their goodness of fit in terms of coefficient of correlation (R2), root mean square error (RMSE) and reduced Chi square ( ). The Wang and Singh model could satisfactorily describe RH-convective drying of carrot slices with R2, RMSE and in the ranges of 0.996-0.999, 5.4 × 10-4-9.4 × 10-4 and 0.0150-0.03353 respectively. The results reveal that a range of 3.61-8.2% retention of β-carotene was observed for every 10% increase in RH in various drying air temperature. In summary, higher temperatures were mainly responsible for β-carotenes degradation however this can be mitigated when drying is conducted under higher RH.

Modelling the Effect of Heavy Metals on the Growth Rate of Enterobacter sp. Strain Neni-13 on SDS

The SDS-degrading bacterium Enterobacter sp. strain Neni-13 was strongly inhibited by mercury. Growth of the SDS-degrading bacterium at various concentrations of mercury shows a sigmoidal pattern with lag periods ranging from 7 to 10 h. As the concentration of mercury was increased, the overall growth was inhibited with 1.0 g/L causing an almost cessation of bacterial growth. The growth rates obtained from the modified Gompertz model was then modelled according to the modified Han-Levenspiel, Wang, Liu, modified Andrews and the Amor models. Out of the five models, only Wang, modified Han-Levenspiel and the Liu models were able to fit the curve, whilst the modified Andrews and Amor models were unable to fit the curves. Both the Wang and modified Han-Levenspiel models show acceptable fitting while the Liu model shows poor fitting. Results of the statistical analysis showed that the Wang model was the best model based on the lowest values for RMSE and AICc, highest adjusted correlation coefficient (adR2) and values of AF and BF closest to unity. The parameters obtained from the Wang model, which are Ccrit, max and m which represent critical heavy metal ion concentration (g/l), maximum growth rate (g/l h) and empirical constant values were 0.216 (95%, confidence interval f 0.193 to 0.239), 1.05 (95%, confidence interval of 0.938 to 1.167) and 0.389 (95%, confidence interval of 0.148 to 0.636) respectively.

Model for Elastic–Plastic Contact Between Rough Surfaces

This paper studies elastic–plastic contact between Greenwood–Williamson (GW) rough surfaces, on which there are many asperities with the same radius whose height obeys the Gaussian distribution. A new plasticity index is defined as the ratio of the standard deviation of the height of asperities on the rough surface to the single-asperity critical displacement (the transition point from the elastic to the elastic-fully plastic deformation regime), which is linearly proportional to the GW plasticity index to the power of 2. The equations for the load/area–separation relationship of rough surfaces are presented based on Wang and Wang's smooth model of singe-asperity elastic–plastic contact, which is an improvement of the Kogut–Etsion (KE) empirical model based on finite element analysis (FEA) data. The load/area–separation relationship can be described by empirical Gaussian functions. The load–area relationship of rough surfaces is approximately linear. The average pressure is only function of the new plasticity index. According to Wang and Wang's conclusion that Etsion et al. single-asperity elastic–plastic loading (EPL) index is approximately equal to the ratio of the single-asperity residual plastic contact displacement to the single-asperity total elastic–plastic contact displacement, the equations for the relationship between Kadin et al. modified plasticity index (MPI) and separation of rough surfaces are also presented. In addition, the MPI is approximately linearly proportional to the separation between rough surfaces for a given new plasticity index ranging from 5 to 30. When the new plasticity index is smaller than 5, due to the large proportion of the elastic deformation in the total deformation, the MPI slightly deviate from linearity.