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CONTENTS
Volume 32, Number 5, March10 2023
 


Abstract
Materials produced with the help of new technology are used in the design of materials used in all science and engineering departments today. A sports engineering and sports equipment department is one of these departments. The use of nanotechnology in sports equipment is one of the most popular uses of this technology today. Nanomaterials have been used in sports equipment for many years, and reputable companies have benefited. Athletes' equipment allows them to display their skills to the fullest extent. It has always been a dream of professional athletes and their coaches to have unique equipment. As a result, engineers have spent all their time and effort solving this problem. Science and engineering can do various things to meet the needs of all sports levels, including specific and detailed designs, the use of appropriate materials, and standardization tests on equipment. However, these aspects must remain aligned with the latest technologies as they develop, just as with other sciences. These technologies, especially nanotechnology, are essential to sports equipment and devices developed today by sports engineers. This article examines the balls that use nanotechnology and can also improve the athlete's performance by using this technology in a specific structure. Using nanotechnology to make nanocomposite poly-hope balls, which makes them lighter and more acceptable, reduces the impact on the ball and increases its movement speed.

Key Words
ball; movement; nanomaterials;nanotechnology;sport

Address
Yongyong Wang and Qixia Jia:Ministry of Sports, Chongqing Jiaotong University, Chongqing 400074, China
Tingting Deng: Second Foreign Language School of Sichuan Foreign Studies University, Chongqing 400074, China

Abstract
This paper studies the effect of the relaxation time on a two-dimensional thermoelastic medium which has a doubly porous structure in the presence of diffusion and gravity. The normal mode analysis is used to obtain the analytic expressions of the physical quantities, which we take the solution form in the exponential image. We have discussed a homogeneous thermoelastic half-space with double porosity with the effect of diffusion and gravity. The equations of generalized thermoelastic material with double porosity structure with one relaxation time have been developed. Moreover, the expressions of many physical quantities are explained. The general solutions, under specific boundary conditions of the problem, were found in some detail. In addition, numerical results are computed.

Key Words
double porosity; homogeneous; L-S theory; normal mode method; thermoelastic diffusion

Address
Mohamed I.A. Othman: Department of Mathematics, Faculty of Science, Zagazig University, P.O. Box 44519, Zagazig, Egypt
Nehal T. Mansour: Basic Sciences Department, Al Safwa High Institute of Engineering, Cairo, Egypt

Abstract
High-speed trains became common nowadays due to the need for fast and safe mean to transport goods and people. However, the use of high-speed trains necessitates the examination of the critical speed, which is the train speed at which the maximum settlement of the railway track occurs. The critical speed and railway track settlement have been investigated considering only one train in previous studies. However, it is normal to have two adjacent trains moving at the same time. This paper aims to understand how the interference of two moving trains affects the settlement and critical speed of ballasted railway track. Calibrated three-dimensional finite element models of railway track subjected to one moving train and two moving trains have been developed to address the aim of the study. It is found that the interference dramatically increases the railway track settlement with a percentage increase ranges between 5 and 100%. It is also found that the percentage increase of the railway track settlement depends on the train speed and the distance between the moving trains. In addition, it is found that the thickness of the ballast layer and the stiffness of the subgrade have minor influence on the percentage increase of the settlement. Importantly, the results of this paper illustrate the importance of the interference of the moving trains on the dynamic response of the railway track. Thus, there is a need to consider the dynamic interaction between the adjacent moving trains in the design of railway track foundation.

Key Words
critical speed; interference effect; moving trains; railway track settlement

Address
Marwah Abbas Hadi and Saif Alzabeebee: Department of Roads and Transport Engineering, University of Al-Qadisiyah, Al-Diwaniyah, Al-Qadisiyah, Iraq
Suraparb Keawsawasvong: Department of Civil Engineering, Thammasat School of Engineering, Thammasat University, Pathumthani, 12120, Thailand

Abstract
In this study, stress relaxation tests were carried out by keeping silt type soil specimens under different strain levels. Decreases in the stress values with time data was collected to better understand the effect of the strain level on the relaxation properties of soil specimens. In addition, the stress relaxation effect on the uniaxial compressive strength (UCS) values of the specimens was investigated with a series of tests. According to the results obtained from this study, the UCS values of the silt specimens significantly vary as a result of the stress relaxation effect. The UCS values were determined to increase with an increase of relaxation strain level to a threshold value. On the other hand, the UCS values were found to be affected adversely in case of high stress levels at the initiation of the relaxation, which are close to the peak level.

Key Words
compressive strength of silts; stress drop; stress relaxation; time-dependent effect

Address
Eren Komurlu: Department of Civil Engineering, Giresun University, Gure, 28200, Giresun, Turkey

Abstract
In tunneling projects, a significant part of the costs is spent on segment production. By more economically producing, the cost of tunnel construction can be greatly reduced, especially in long and large-diameter tunnels. In the present study, the effect of using the Carousel method in the improvement of the production system performance compared to the conventional Static system has been studied. To carry out the research, a quantitative comparison of cost and production time was carried out for two production methods using the available documentation. The opinions of experts have been obtained using questionnaires and qualitative comparison of cost, time and production quality was done by implementation of statistical analysis. The SPSS software and the univariate t-test were used to analyze the questionnaires. According to the results of statistical analysis with SPSS, the use of the Carousel method will reduce production time and costs along with increasing manufacturing quality. According to the documentation analysis, the Carousel method reduces the cost of production by almost 30% and leads to a reduction of the production time to approximately 40% of the Static moulds system. The Carousel method has a higher production rate, efficiency, and better performance. Research into quantifying the benefits of Carousel method in the production system performance is very limited. This comparison is based on real information from the under construction Tabriz Metro project. This article can be very helpful in choosing the best production method.

Key Words
carousel method; cost and quality; prefabricated segments; production time, statistical analysis; Tabriz Metro

Address
Elaheh Banihashemigargari: Master of Industrial management, Tabriz, Iran
Amir H. Rezaeifarei: Department of Civil Engineering, Azarbaijan Shahid Madani University, Tabriz,35 km. of Maragheh Hwy, Iran

Abstract
Temperature is one of the most critical elements that influence the rutting and fatigue resistance of flexible pavements. Particularly in extreme hot regions in Saudi Arabia, high temperature would significantly reduce the rutting resistance of flexible pavements leading to reduction of pavement service life. Due to the impacts of global warming, average temperature in Saudi Arabia is expected to further increase by about 4C by the end of the 21st century. The substantial increase in average temperature will elevate the expected pavement maintenance and rehabilitation cost. This paper analyzes the structural effects of temperature on pavement using layered elastic analysis based on finite element techniques. The research team calculated the potential loss of pavement service life due to the projected temperature increase and climate change. The paper also analyzed potential impact of using carbon waste in asphalt concrete to tackle the derogatory impacts of temperature rise.

Key Words
carbon waste; finite element analysis; multilayered pavement; thermal effect

Address
Amin Hamdi: Department of Civil and Environmental Engineering, Faculty of Engineering, King Abdulaziz University, Jeddah, Saudi Arabia

Abstract
The failure of slope can cause remarkable damage to either human life or infrastructures. Stabilizing piles are widely utilized to reinforce slope as a slip-resistance structure. The workability of pile-stabilized slopes is affected by various parameters. In this study, the performance of earth slope reinforced with piles and the behavior of piles under static load, by shear reduction strength method using the finite difference software (𝐹𝐿𝐴𝐶3𝐷) has been investigated. Parametric studies were conducted to investigate the role of pile length (𝐿), different pile distances from each other (𝑆/𝐷), pile head conditions (free and fixed head condition), the effect of sand density (loose, medium, and high-density soil) on the pile behavior, and the performance of pile-stabilized slopes. The performance of the stabilized slopes was analyzed by evaluating the factor of safety, lateral displacement and bending moment of piles, and critical slip mechanism. The results depict that as L increased and 𝑆/𝐷 reduced, the performance of slopes stabilized with pile gets better by raising the soil density. The greater the amount of bending moment at the shallow depths of the pile in the fixed pile head indicates the effect of the inertial force due to the structure on the pile performance.

Key Words
3D numerical analysis; free and fixed head pile; FLAC3D; pile-slope system; shear strength reduction method

Address
Xixi Xiong, Ying Fan and Jinzhe Wang: College of Civil Engineering, Architecture and Environment, Hubei University of Technology, Wuhan, Hubei Province 430068, China
Pooya Heydari: Department of Geotechnical engineering, Moghadas Ardabili Institute of Higher Education, Ardabil, Iran

Abstract
Snap-buckling is one of the main failure modes of structures, because it will lead to the reduction of structural bearing capacity, durability loss and even structural damage. Boundary condition plays an important role in the research of engineering mechanics. Further discussion on the boundary conditions problems will help to analyze the dynamic and static behavior of structures more accurately. Therefore, in order to understand the dynamic and static behavior of curved beams more comprehensively, this paper mainly studies the nonlinear snap-through buckling and forced vibration characteristics of functionally graded graphene reinforced composites (FG-GPLRCs) curved beams with two different boundary conditions (including clamped-hinged and hinged-hinged) using Euler-Bernoulli beam theory (E-BBT). In addition, the effects of the curved beam radius, the GLPs distributions, number of GLPs layers, the mass fraction of GLPs and elastic foundation parameters on the nonlinear snap-through buckling and forced vibration behavior are discussed respectively.

Key Words
boundary condition; curved beams; resonance; snap-through buckling; two-step perturbation method

Address
Lei-Lei Gan and Gui-Lin She: College of Mechanical and Vehicle Engineering, Chongqing University, Chongqing 400044, China


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