Moving mesh methods for numerical solution of porous medium equations

Porous medium equation (PME) has been found in many applications of the physical sciences. The equation is nonlinear, degenerate, and in many situations has a free boundary, which altogether pose great challenges for mathematical and numerical analyses. In contrast with the mathematical development of PME, which began in the 1950s and has since had much success, studies of numerical solution did not appear until the 1980s. Though a significant progress has been made since then for the 1D setting, only limited success has been observed for 2D cases. In this dissertation, we will propose several moving mesh methods which improve the accuracy and convergence order of the PME numerical solution

Experimental and Numerical Investigations on Flexural Behaviour of Prestressed Textile Reinforced Concrete Slabs

Nowadays, concrete is mostly prestressed with steel. But the application of prestressing steel is restricted in a highly corrosive environment area due to corrosion of prestressing steel, leading to a reduction in strength and may cause sudden failure. Carbon textile is considered an alternate material due to its corrosive resistance property, high tensile strength, and perfectly elastic. Prestressing is also the only realistic way to utilize fully ultra-high tensile strength in carbon textile material. In this study, experimental and numerical analyses were carried out for the flexural behaviour of prestressed and non-prestressed carbon textile reinforced concrete slabs. This study also focuses on the influences of textile reinforcement ratios, prestressing grades on the flexural behaviour of carbon textile reinforced concrete (TRC). Fifteen precast TRC slabs were tested, of which six were prestressed to various levels with carbon textile. The obtained results show that prestressing textile reinforcement results in a higher load-bearing capacity, stiffness, and crack resistance for TRC slabs. The first-crack load of the prestressed specimens increased by about 85% compared with those of non-prestressed slabs. Three-dimensional finite element models were developed to provide a reliable estimation of global and local response. The modeling techniques accurately reproduced the experimental behaviour. Doi: 10.28991/cej-2021-03091712 Full Text: PD

Comparison of distance rock tests with school children using standard sloan English letter targets versus modified Landolt C targets

The distance rock test was first introduced in 1975. Since then there are several studies using the distance rock test at various clinics. So far, English letters have been used as far-near-far targets at 20/80 and 20/25 acuity levels. The tests were administered to children of different age groups. In this study, some aspects of the original Haynes distance rock test such as letter features and target spacing were changed. Specifically, the Landolt Cs were modified and used as new targets in the far-near-far discriminatory tasks. Forty four fourth graders and twenty six first graders were selected for the study. The relative response times of the visual system were measured. The results indicate 1) The fourth graders performed better than the first graders under all possible combinations of the test conditions; 2) Both fourth and first graders called out English letters quicker than Landolt Cs; 3) Fourth graders identified widely spaced Landolt Cs quicker than regularly spaced ones; and 4) Both fourth and first graders called out targets at the 20/80 acuity quicker than those at the 20/25 acuity. Both optometric and psychological factors were considered to explain the students\u27 performance. Automaticity as a function of maturity, practice and learning played a significant role in distance rock responses. Automaticity was shown to be present in distance rock performance since its characteristics were detected in this study. Indications for procedural changes and clinical utilization were also discussed

Outcome versus process value in service delivery

Purpose: This study is embedded in social exchange and transaction cost theories. The objective is twofold: First, to compare the relative importance of process value and outcome value in building affective and cognitive relationship strength; and second, to compare the relative effects of each type of relationship strength on attitudinal and behavioral loyalty. Design/methodology/approach: This empirical study features a quantitative approach. The sample comprises 167 business-to-business (B2B) customers of a large transportation and logistics company in Vietnam. Findings: Process value and outcome value have different effects on affective relationship strength: The effect of process value is greater than that of outcome value. In addition, cognitive strength has a stronger impact on both attitudinal and behavioral loyalty than affective strength. Research limitations/implications: These insights extend extant literature regarding the process and outcome components of the service assessment. Further studies also should employ a cross-industry, cross-country sample to examine the potential moderating effects of country- or industry-specific factors. These findings show B2B managers how to make appropriate resource allocation and investment decisions to enhance relationship strength and resulting customer loyalty. Originality/value: To clarify the links among customer value, relationship strength and customer loyalty, this study examines the relative importance of rational and non-rational factors (i.e., process value vs. outcome value; affective strength vs. cognitive strength) for relationship performance. Unlike most prior research, this study is set in the B2B context of a developing country

Speedup of Interval Type 2 Fuzzy Logic Systems Based on GPU for Robot Navigation

As the number of rules and sample rate for type 2 fuzzy logic systems (T2FLSs) increases, the speed of calculations becomes a problem. The T2FLS has a large membership value of inherent algorithmic parallelism that modern CPU architectures do not exploit. In the T2FLS, many rules and algorithms can be speedup on a graphics processing unit (GPU) as long as the majority of computation a various stages and components are not dependent on each other. This paper demonstrates how to install interval type 2 fuzzy logic systems (IT2-FLSs) on the GPU and experiments for obstacle avoidance behavior of robot navigation. GPU-based calculations are high-performance solution and free up the CPU. The experimental results show that the performance of the GPU is many times faster than CPU

Experimental and Numerical Evaluation of Concentrically Loaded RC Columns Strengthening by Textile Reinforced Concrete Jacketing

Nowadays, Textile Reinforced Concrete (TRC) has become a very popular strengthening technique for concrete structures. This paper presents an investigation on the applicability of TRC for strengthening reinforced concrete column. Both experimental and numerical studies are conducted to evaluate the confinement effects of various TRC strengthening schemes. The experimental study is performed on a series of six reinforced concrete square columns tested to failure. Two of them were un-strengthened as references, the other four were strengthened by one or two layers of Carbon Textile Reinforced Concrete (CTRC). The results indicated that the application of carbon TRC enhanced the ductility and ultimate strength of the specimens. Failure of all strengthened columns was together with tensile rupture of textile reinforcements at the corners of column. Finite element models of the CTRC strengthened columns based on ATENA software package were developed and verified with the experimental results. The analytical results show that in the specimen corner areas, textile reinforcements are subjected to a 3D complicated stress state and this may be the cause of their premature failure

Simple thermal-electrical model of photovoltaic panels with cooler-integrated sun tracker

This paper presents a simple thermal-electrical model of a photovoltaic panel with a cooler-integrated sun tracker. Based on the model and obtained weather data, we analyzed the improved overall efficiency in a year as well as the performance in each typical weather case for photovoltaic panels with fixed-tilt systems with a tilt angle equal to latitude, fixed-tilt systems with cooler, a single-axis sun tracker, and a cooler-integrated single-axis sun tracker. The results show that on a sunny summer day with few clouds, the performance of the photovoltaic panels with the proposed system improved and reached 32.76% compared with the fixed-tilt systems. On a sunny day with clouds in the wet, rainy season, because of the low air temperature and the high wind speed, the photovoltaic panel temperature was lower than the cooler’s initial set temperature; the performance of the photovoltaic panel with the proposed system improved by 12.55% compared with the fixed-tilt system. Simulation results show that, over one year, the overall efficiency of the proposed system markedly improved by 16.35, 13.03, and 3.68% compared with the photovoltaic panel with the fixed-tilt system, the cooler, and the single-axis sun tracker, respectively. The simulation results can serve as a premise for future experimental models