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CONTENTS
Volume 13, Number 2, August 2022
 


Abstract
In this paper, a finite element (FE) simulation has been developed in order to examine the nonlinear stability of reinforced sandwich beams with graphene oxide powders (GOPs). In this regard, the nonlinear stability curves have been obtained asuming that the beam is under compressive loads leading to its buckling. The beam is considered to be a three-layered sandwich beam with metal core and GOP reinforced face sheets and it is rested on elastic substrate. Moreover, a higher-order refined beam theory has been considered to formulate the sandwich beam by employing the geometrically perfect and imperfect beam configurations. In the solving procedure, the utalized finite element simulation contains a novel beam element in which shear deformation has been included. The calculated stability curves of GOP-reinforced sandwich beams are shown to be dependent on different parameters such as GOP amount, face sheet thickness, geometrical imperfection and also center deflection.

Key Words
finite element method; nonlinear stability; numerical simulation; sandwich beam

Address
Yuxin Zheng, Hongwei Jin and Congying Jiang: School of Civil Engineering and Architecture, Zhejiang Guangsha Vocational and Technical University of Construction, Dongyang 322100, Zhejiang, China


Abstract
Emerge of nanotechnology impacts all aspects of humans' life. One of important aspects of the nanotechnology and nanoparticles (NPs) is in the food production industry. The safety of such foods is not well recognized and producing safe foods using nanoparticles involves delicate experiments. In this study, we aim to incorporate intelligent computer simulation in predicting safety degree of nanofoods. In this regard, the safety concerns on the nano-foods are addressed considering cytotoxicity levels in metal oxides nanoparticles using adaptive neuro-fuzzy inference system (ANFIS) and response surface method (RSM). Three descriptors including chemical bond length, lattice energy and enthalpy of formation gaseous cation of 15 selected NPs are examined to find their influence on the cytotoxicity of NPs. The most effective descriptor is selected using RSM method and dependency of the toxicity of these NPs on the descriptors are presented in 2D and 3D graphs obtained using ANFIS technique. A comprehensive parameters study is conducted to observe effects of different descriptors on cytotoxicity of NPs. The results indicated that combinations of descriptors have the most effects on the cytotoxicity.

Key Words
biological activity; cytotoxicity, nano-food; neuro-fuzzy system; response surface method

Address
Yunfeng Zhao: Analysis and Testing Center, Yancheng Institute of Technology, Yancheng 224051, Jiangsu, China

Le Zhang: School of Public Health and Management, Shandong First Medical University & Shandong Academy of Medical Sciences, Taian 271016, Shandong, China


Abstract
The accurate assessment of the performance of nonuniform systems requires a thorough understanding of stability analysis. As a result, the theoretical modeling of the influence of various variables on the performance of small-scale nonuniform structures with conventional and non-conventional geometries is presented in this paper. According to the fundamental computer simulation based on mathematical and mechanical principles, the stability of the nonuniform structures is examined. Thus, a numerical procedure is used to simulate the stability and instability characteristics of the nonuniform small-scale structures via computer aid. Theoretic simulation methods provide a great deal of the design and production of small-scale structures at a low cost compared to experimental simulations. Thus, this paper provides a good presentation of the stability analysis of the nonuniform nanoscale structures with high accuracy without actual experimental.

Key Words
computer simulation; nonuniform structures; numerical procedure; small-scale structures; stability analysis

Address
Chunping Wang: School of Communication and Information Engineering, Shanghai Technical Institute of Electronics & Information, Shanghai 201141, China/ Dean's Office, Shanghai Technical Institute of Electronics & Information, Shanghai 201141, China

Keming Chen: Dean's Office, Shanghai Technical Institute of Electronics & Information, Shanghai 201141, China

Abstract
This article investigates the longitudinal vibration of a nanorod embedded in viscoelastic medium according to the nonlocal strain gradient theory. Viscoelastic medium is considered based on Kelvin-Voigt model. Governing partial differential equation is derived based on longitudinal equilibrium and analytical solution is obtained by adopting harmonic motion solution for the nanorod. Modal frequencies and corresponding damping ratios are presented to demonstrate the influences of nonlocal parameter, material length scale, elastic and damping parameters of the viscoelastic medium. It is observed that material length scale parameter is very influential on modal frequencies especially at lower values of nonlocal parameter whereas increase in length scale parameter has less effect at higher values of nonlocal parameter when the medium is purely elastic. Elastic stiffness and damping coefficient of the medium have considerable impacts on modal frequencies and damping ratios, and the highest impact of these parameters on frequency and damping ratio is seen in the first mode. Results calculated based on strain gradient theory are quite different from those calculated based on classical elasticity theory. Hence, nonlocal strain gradient theory including length scale parameter can be used to get more accurate estimations of frequency response of nanorods embedded in viscoelastic medium.

Key Words
longitudinal vibration; nanorod; nonlocal elasticity; strain gradient theory; viscoelastic medium

Address
Mehmet N. Balci: Department of Mechanical Engineering, Hacettepe University, 06800, Ankara, Turkey

Abstract
In the present study, a hybrid model of artificial neural network (ANN) and internet of things (IoT) is proposed to overcome the difficulties in deriving governing equations and numerical solutions of the dynamical behavior of the nano-systems. Nano-structures manifest size-dependent behavior in response to static and dynamic loadings. Nonlocal and length-scale parameters alongside with other geometrical, loading and material parameters are taken as input parameters of an ANN to observe the natural frequency and damping behavior of micro sensors made from nanocomposite material with piezoelectric layers. The behavior of a micro-beam is simulated using famous numerical methods in literature under base vibrations. The ANN was further trained to correlate the output vibrations to the base vibration. Afterwards, using IoT, the electrical potential conducted in the sensors are collected and converted to numerical data in an embedded mini-computer and transferred to a server for further calculations and decision by ANN. The ANN calculates the base vibration behavior with is crucial in mechanical systems. The speed and accuracy of the ANN in determining base excitation behavior are the strengths of this network which could be further employed by engineers and scientists.

Key Words
artificial neural network; base vibration; internet of things; nano-systems; sensors

Address
Wei Ren: School of Computer and Information Sciences, University of the Cumberlands, Williamsburg, KY 40769, USA

Xiaochen Wu: College of Science and Technology, Bellevue University, Bellevue NE 68005, USA

Rufeng Cai: Shanghai Huwen Technology Co., Ltd., Pudong, Shanghai 201203, China

Abstract
This study is a randomized pretest-posttest design that aims to investigate the effect of early entrepreneurship education on cognitive and non- early entrepreneurship education, non-cognitive skills, creativity, self-efficacy, Bizworld cognitive skills of male sixth-grade primary school students. A total of 45 students were selected by multi-stage random sampling method and were assigned randomly to experimental, active-control and control groups. The experimental group received entrepreneurship education based on the Bizworld entrepreneurship program. The results indicate that early entrepreneurship education had an effect on non-cognitive skills (such as risk taking propensity, creativity, self-efficacy, persistence and need for achievement. It seems that early entrepreneurship education is a proper strategy to develop children's non-cognitive skills in late years of primary school. These skills will affect children's individual, educational, social and occupational future and can have long term benefits for students, families and society.

Key Words
Bizworld; creativity; early entrepreneurship education; non-cognitive skills; self-efficacy

Address
Jie Meng, Ruilan Zhong and Min Dong: Department of Hematology, The Second Affiliated Hospital of Hainan Medical University, Haikou 570000, China

Zhiqiang Wu: Department of Electrical Engineering, Wright State University, Dayton 45435, USA

Abstract
The synthesis of organic and hybrid organic-inorganic perovskites directly from solution improves the cost- and energy-efficiency of processing. To date, numerous research efforts have been devoted to investigating the influence of the various solvent parameters for the synthesis of lead halide perovskites, focused on the effects of different single solvents on the efficiency of the resulting perovskites. In this work, we investigated the effect of solvent blends for the first time on the structure and phase of perovskites produced via the Lewis base vapor diffusion method to develop a new synthetic approach for water-stable CsPbBr3 particles with nanometer-sized dimensions. Solvent blends prepared with DMF and water-miscible solvents with different Gutmann's donor numbers (DN) affect the Pb ions differently, resulting in a variety of lead bromide species with various colors. The use of a DMF/isopropanol solvent mixture was found to induce the formation of the Ruddlesden–Popper perovskite based on lead bromide. This perovskite undergoes a blue color shift in the solvated state owing to the separation of nanoplatelets. In contrast, the replacement of isopropanol with DMSO, which has a high DN, induces the formation of spherical CsPbBr3 perovskite nanoparticles that exhibit green emission. Finally, the integration of acetone in the solvent system leads to the formation of lead bromide complexes with a yellow-orange color and the perovskite CsPbBr3.

Key Words
Gutmann's donor number; Lewis-base vapor diffusion; multicolor lead bromide perovskite; perovskite phase structure control; water-stable

Address
Mirkomil Sharipov, Soojin Hwang, Won June Kim: Department of Chemistry, Changwon National University, Changwon 51140, Republic of Korea

Bui The Huy and Yong-Ill Lee: Department of Chemistry, Changwon National University, Changwon 51140, Republic of Korea/ Faculty of Chemical Engineering, Industrial University of Ho Chi Minh City, Ho Chi Minh City, Vietnam

Salah M. Tawfik: Department of Chemistry, Changwon National University, Changwon 51140, Republic of Korea/ Department of Petrochemicals, Egyptian Petroleum Research Institute, Cairo, 11727 Egypt

Abstract
We present the high-brightness large-area 10.1" in-cell polarizer display panel integrated with a wire grid polarizer (WGP) and metal reflector, from the initial design to final system development in a commercially feasible level. We have modeled and developed the WGP architecture integrated with the metal reflector in a single in-cell layer, to achieve excellent polarization efficiency as well as brightness enhancement through the light recycling effect. After the optimization of key experimental parameters via Taguchi method, the roll nanoimprint lithography employing a flexible large-area tiled mold has been utilized to create the 90 nm-pitch polymer resist pattern with the 54.1 nm linewidth and 5.1 nm residual layer thickness. The 90 nm-pitch Al gratings with the 51.4 nm linewidth and 2150 Å height have been successfully fabricated after subsequent etch process, providing the in-cell WGPs with high optical performance in the entire visible light regime. Finally we have integrated the WGP in a commercial 10.1" display device and demonstrated its actual operation, exhibiting 1.24 times enhancement of brightness compared to a conventional film polarizer-based one, with the contrast ratio of 1,004:1. Polarization efficiency and transmittance of the developed WGPs in an in-cell polarizer panel achieve 99.995 % and 42.3 %, respectively.

Key Words
in-cell polarizer; large-area display; roll nanoimprint lithography; Taguchi method; tiling method; wire grid polarizer

Address
Dae-Young Lee, Jung-Gun Nam, Yun-Jong Yeo and Sang-Hwan Cho: Display Research Center, Samsung Display, 1 Samsung-ro, Yongin-si, Gyeonggi-do, 17113 Korea

Kang-Soo Han: Large Display Process Development Team, Samsung Display, 1 Samsung-ro, Yongin-si, Gyeonggi-do, 17113 Korea

Useung Lee and Jong G. Ok: Department of Mechanical and Automotive Engineering, Seoul National University of Science and Technology, 232 Gongneung-ro, Nowon-gu, Seoul 01811, Korea



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