Papers by Keyword: Mass

Abstract: This study explores the integration of GiD pre-processing software with ETABS to enhance the finite element modeling of large, complex, multi-story buildings under diverse loading conditions. The research highlights the benefits of using GiD for customized meshing of slab systems, which allows for precise control over mesh density and element quality. Through a case study of an eight-story reinforced concrete structure, the study demonstrates how GiD improves analysis accuracy and computational efficiency by reducing process time and minimizing mesh-related errors. The results indicate that GiD’s refined meshing capabilities enhances the structural model’s accuracy, improving load distribution, straining actions calculations, deflection accuracy, and load transfer representation under gravity loads. In addition, GiD’s approach leads to more reliable predictions of natural periods, lateral displacements, and story drifts under seismic conditions. This integration offers valuable insights for engineers seeking to optimize FEA workflows for complex structures.

Abstract: This study aims to determine the optimal conditions of acid-activated clay adsorbent in adsorption of Pb²⁺ metal ions. Clay was taken around East Kalimantan, Karang Joang. This adsorbent was prepared by mixing clay into a solution of KMnO₄, H₂SO₄ and HCl successively, and stirred for 4 hours at a temperature of 80°C. The morphology and active groups of the adsorbent were analyzed using BET and FTIR. The variables of this study were the mass of the adsorbent 0.1, 0.3 and 0.5 grams and the contact time of 5, 30 and 55 minutes. Adsorption capacity of this adsorbent was analyzed using Atomic Absorption Spectrophotometry (AAS). The results of this study indicate that the optimum mass of adsorbent is 0.1 g, and contact time is 30 minutes. Adsorption capacity of Pb²⁺ metal ions by acid-activated clay adsorbent at the optimum condition of 0.1 gram was 23,585 mg/g and adsorption energy was 2,338 kJ/mol. Meanwhile, at the optimum condition for 30 minutes, the adsorption capacity was 0.771 mg/L, and the adsorption energy was 2.895 kJ/mol. So that the adsorption process in this study can be known, namely physical adsorption because the adsorption energy value is less than 40 kJ/mol.

Abstract: The manufacture of ceramic brick goes through the stages of raw material extraction, clay homogenization, material conformation, drying and firing. Drying is the phase that needs greater care, as it involves removing part of the moisture from the brick, in order to preserve its quality after process. This work aims to predict heat and mass transfer in the drying of ceramic bricks in oven using computational fluid dynamics. Considering the constant thermophysical properties, a transient three-dimensional mathematical model was used to predict mass and energy transfer between the material and air during the process. Drying simulations at temperature of 100°C were performed with the air flow in the frontal direction to the ceramic brick holes and the results were compared with those obtained for the air flow in the perpendicular direction to the brick holes reported in the literature. It was found that the position of the brick in relation to the direction of air flow inside the oven affected directly the drying and heating kinetics, and the distribution of temperature and moisture content inside the brick. The positioning of the holes in the brick parallel to the direction of the air flow resulted in reduction at the drying time and, consequently, in energy savings in the process, more uniform drying, and improvement in the product quality.

Abstract: The results of selection and principles of calculating the ceramic masses composition for the clinker tiles’ production from argillites taking into account the raw materials’ characteristics are presented. The positive properties of argillites, as well as the properties that do not allow the tiles’ production of by stamping, which is traditional for these products’ manufacturing, are noted. Having low sensitivity to drying, low air shrinkage, high strength of the calcined shard, while being fusible sintering raw materials, argillites are low plastic and have insufficient bonding during molding, which indicates the need for corrective additives. In this work, the task to select the composition of ceramic masses to increase the plasticity of argillites while maintaining the positive properties of the main raw material was set. The authors proposed the use of siliceous clays as a corrective additive. An integrated approach was applied in calculating ceramic masses by grain composition and chemical and mineralogical indicators. Based on the research of A.I. Avgustinik, the oxide content Ca, Mg, Fe, Na, K and attitude Al₂O₃/SiO₂ was taken into account. In order to obtain the densest packing, when calculating the grain composition, the natural dispersion of siliceous clays and the grain composition of previously prepared argillites were taken into account. The obtained theoretical calculations were tested in practice. Practical results showed that the 15% introduction of siliceous clay with the ceramic mass composition made it possible to obtain clinker tiles with improved physical and mechanical properties.

Abstract: This paper aims to study convective drying of industrial hollow bricks in a tunnel dryer. A transient mathematical model based on the heat and mass conservation equations applied to the air and brick was derived and the numerical solution (finite-volume method) of the governing equations is presented. Predicted and experimental data of the average moisture content and the temperature of the product during the drying process are compared and a good concordance was verified. Numerical results inside the bed confirm an almost null difference between the moisture content along the process. Similar behavior was verified to the product temperature. These results confirm an efficient drying process.

Abstract: Several studies about drying of ceramic materials have been developed in many engineering and fabrication sectors. This process requires high investments and high energy consumption, resulting in high costs to the companies of this sector. In many situations, it is common the use of theoretical solutions that allow, with relative ease and low cost, to change the operational and geometrical conditions of the dryer or object of drying, to obtain the optimized operational conditions. In this sense, this work aims to predict the drying process of a ceramic brick in an oven using the computational fluid dynamics analysis. For a drying temperature of 80°C, the results of the drying and heating kinetics, and the moisture content and temperature distributions of the product and the air and the air velocity and pressure in the oven are shown and analyzed. A comparison between the predicted and experimental data of the average moisture content and temperature of the brick along the process was done and a good agreement was obtained.

Abstract: Food drying is one of the most used methods of preservation. To accurately describe moisture migration within biological products (grains, fruits, vegetables, etc.) during drying and explain the effects of this process on the quality of the material, have been proposed several mathematical models, but few incorporate the phenomena of simultaneous heat and mass transport applied to complex geometry. In this sense, this paper aims to present a mathematical model, based on the thermodynamics of irreversible processes to describe the heat and mass transfer (liquid and vapor) during the drying of bodies with oblate spheroidal geometry. This model was applied to describe drying of lentil, considering the variables transport coefficients and equilibrium conditions at the surface of the solid. Results of the average moisture content, average temperature, liquid flux, vapor flux, and moisture content and temperature distributions inside a lentil kernel during drying process, at different temperatures (40 and 60 oC) were presented and analyzed.

Abstract: The drying process can be defined how unit operation for removing water of one moist solid to an unsaturated gaseous phase due to heat transfer. Numerical simulation emerges like a tool that allows the reproduction of drying experiments using computers and suitable softwares. In this sense, this works aims to predict drying process of an industrial hollow ceramic brick inside the kiln using computational fluid dynamics analysis. For one drying temperature of 60°C, results of the drying and heating kinetics, and moisture content, velocity and temperature distributions are shown and analyzed. A comparison between predicted and experimental data of the moisture content and temperature of the brick along the process was done and a good agreement was obtained.

Abstract: The loss of vertical structures stability is always a very dangerous phenomenon. It is almost impossible to predict it, because it develops very quickly, avalanche-like. One solution to this problem is to increase the cross section of the compressible elements. However, this solution leads to a significant increase in weight and load on the underlying structures. It is necessary to be able to accurately determine the critical force of F_cr for various forms of compressible elements and schemes of fastening. The article presents the solution of the problem of fiberglass rods stability by the energy method in the form of Tymoshenko-Ritz, which is reduced to the problem of determining eigenvalues in the algebraic theory of matrices. In the MatLab software complex, the value of the critical load F_cr is obtained by numerical method with different stiffness and pinning schemes.

Abstract: Deceptive promotions occur frequently on Taobao Mall, Jd Mall and other net-shopping platforms, which not only affecting the focus online store, but also having favorable or adverse impact on other competing online stores, and cause spillover effect. From the perspective of mass and frequency, this paper used the scenario experiment method to explore the effect of deceptive promotion’s characteristics on negative spillover effect to other competing online stores. The study found that the higher the mass of deceptive promotion is, the stronger negative spillover effect of deceptive promotion from the focus online store to competing online stores is, and the higher the frequency of deceptive promotion is, the stronger negative spillover effect of deceptive promotion from the focus online store to competing online stores is. Frequency moderates the effect of mass on negative spillover effect to competing online stores; under the condition of low-frequency, there are not significant differences between high-mass group and low-mass group; under the condition of high-frequency, spillover effect of high-mass group was significantly stronger than that of low-mass group. In practice, this paper explains the effect of the characteristics of deceptive promotions on spillover effect, which provides valuable reference for competing online stores to predict spillover effect of deceptive promotion effectively.