The effect of porosity and number of unit cell on applicability of volume average approach in closed cell porous media

Purpose The purpose of this study is to investigate the applicability of volume average which is extensively used for analyzing the heat and fluid flow (both for single-phase and solid/liquid-phase change) in a closed cell porous medium numerically. Design/methodology/approach Heat conduction equations for the solid frame and fluid (or phase change material) are solved for pore scale and volume average approaches. The study mainly focuses on the effect of porosity and the number of porous media unit cell on the agreement between the results of the pore scale and volume average approaches. Findings It is observed for the lowest porosity values such as 0.3 and the number of porous media unit cell as 4 in heat transfer direction, the results between two approaches may be questionable for the single-phase fluid. By increasing the number of porous media unit cell in heat transfer direction, the agreement between two approaches becomes better. In general, for high porosity values (such as 0.9) the agreement between the results of two approaches is in the acceptable range both for single-phase and solid/liquid-phase change. Two charts on the applicability of volume average method for single-phase and solid/liquid-phase change are presented. Originality/value The authors’ literature survey shows that it is the first time the applicability of volume average which is extensively used for analyzing the heat and fluid flow in a closed cell porous medium is investigated numerically.

Calibration of CFD Numerical Model for the Analysis of a Combined Caisson

The purpose of this work is the calibration of a numerical model for simulating the interaction of waves with a composite caisson having an internal rubble mound to dissipate incident sea wave energy. In particular, the analysis focused on the reflection coefficient and the pressure distribution at the caisson vertical walls. The numerical model is based on the Volume-Average Reynolds-Averaged Navier–Stokes (VARANS) equations. Through three closure terms (linear, nonlinear, and transition), such equations take into account some phenomena that cannot be dealt when the volume-average method is used (i.e., frictional forces, pressure force, and added mass). To reproduce properly the real phenomena, a calibration process of such terms is necessary. The reference data used in the calibration process were obtained from an experimental campaign carried out at the Hydraulics Laboratory of the University of Messina. The calibration process allowed the proper prediction of certain phenomena to be expressed as a function of different closing terms. In particular, it was estimated that the reflection coefficient and the wave loading at the frontal wall are better reproduced when all three terms are considered, while the force at the rear wall is better simulated when the effects of such terms are neglected.

The Mode Heuristic in Service Consumers’ Interpretations of Online Rating Distributions

In this article, the authors demonstrate a tendency among consumers to use the arithmetic mode as a heuristic basis when drawing inferences from graphical displays of online rating distributions in such a way that service evaluations inferred from rating distributions systematically vary by the location of the mode. The rationale underlying this phenomenon is that the mode (i.e., the most frequent rating which is represented by the tallest bar in a graphical display) attracts consumers’ attention because of its visual salience and is thus disproportionately weighted when they draw conclusions. Across a series of eight studies, the authors provide strong empirical evidence for the existence of the mode heuristic, shed light on this phenomenon at the process level, and demonstrate how consumers’ inferences based on the mode heuristic depend on the visual salience of the mode. Together, the findings of these studies contribute to a better understanding of how service customers process and interpret graphical illustrations of online rating distributions and provide companies with a new key figure that—aside from rating volume, average ratings, and rating dispersion—should be incorporated in the monitoring, analyzing, and evaluating of review data.

DINVESTIGATION OF CONTACT HEATING OF FRUIT AND VEGETABLES WITH SATURATED WATER STEAM

The purpose of this research was to study the modes of heating different types of plant raw materials in model technological environments that imitate the blanching of raw materials under factory conditions. The research aimed at expanding the range of canned products made from fruit and vegetables. To this end, new methods were searched for, in addition to the existing ones, allowing heating various plant raw materials and increasing the energy efficiency of canned fruit and vegetables production. Saturated water steam was selected as the treatment medium. The experimental studies included determining the volume-average temperature of the fruit layer in the container. A pulse method of supplying the heating media has also been investigated. It allows using the inertial properties of raw materials and significantly reducing the expenditure of the heating media. The objects selected for study were various species of pomes and drupes, in particular, apples, plums, cherries, sweet cherries, as well as a vegetable crop of the gourd family, or Cucurbitaceae. The following characteristics have been studied: the dynamics of heating individual fruit and vegetables in the saturated water steam environment at atmospheric pressure; the dependence of the heating and cooling rates of individual fruit and vegetables on the geometric index; the dependence of the heating rate of individual fruit and vegetables on the value of the characteristic dimension; the dependences of changes in the volume-average temperature of the fruit layer on the duration of treatment with saturated water steam. It has been established that the volume-average temperature in the centre of a fruit is also influenced by the shape of the fruit itself. To characterise the anomalous shapes of plant raw materials, the geometric index G has been calculated. This index characterises the elliptical shape of a fruit, and allows determining parameters in two mutually perpendicular planes. Also, to compare fruit of the elliptical and the spherical shapes, a special concept of characteristic dimension was used, which is applicable to fruit of different shapes. The experimental data on the change in the dependences of the heating and cooling rates of individual elliptical fruit have been analysed. The analysis has shown that the size of a fruit significantly affects the volume-average temperature in the fruit layer. It has been suggested to use pulsed heating of the fruit layer with saturated water steam, which will appreciably increase the energy efficiency of production due to a significant reduction in heating media consumption

Application of Developers’ and Users’ Dependent Factors in App Store Optimization

This paper presents an application of developers' and users' dependent factors in the app store optimization. The application is based on two main fields: developers’ dependent factors and users’ dependent factors. Developers’ dependent factors are identified as: developer name, app name, subtitle, genre, short description, long description, content rating, system requirements, page url, last update, what’s new and price. Users’ dependent factors are identified as: download volume, average rating, rating volume and reviews. The proposed application in its final form is modelled after mining sample data from two leading app stores: Google Play and Apple App Store. Results from analyzing collected data show that developer dependent elements can be better optimized. Names and descriptions of mobile apps are not fully utilized. In Google Play there is one significant correlation between download volume and number of reviews, whereas in App Store there is no significant correlation between factors.

Umur Memengaruhi Volume Semen dan Motilitas Spermatozoa Babi Landrace di Balai Inseminasi Buatan Baturiti, Tabanan, Bali (AGE AFFECTS SEMEN VOLUME AND MOTILITY OF SPERMATOZOA LANDRACE BOAR’S OF BATURITI ARTIFICIAL INSEMINATION CENTER, TABANAN, BALI)

Sperm quality have been associated with age for many years. This study aims to determine the inffluence of age to the volume and motility of Landrace boar’s sperm at Baturiti Artificial Insemination (AI) center. A Total of 300 ejaculates were used in this study. An ejaculate origin from five boar are a collection of five month. A complete randomized design (CRD) was used with two different boar of block ages, block A (2-4 year) and block B (6-8 year). Three or four glass slides were prepared for each boar sample; a drop of semen was placed on each glass slides. This sample was examined under the light microscope on five view field in each glass slides. The result of the research show that the Landrace boars in block A have semen volume average 273.60 mL and sperm motility 73.86%, while in block B the average semen volume was 107.66 mL and sperm motility 62.92%. It can be concluded that Landrace boars in block A had higher volume and sperm motility compared to Landrace boars in block B.