Numerical forced vibration analysis of compositionally gradient porous cylindrical microshells under moving load and thermal environment

Jianwei Shi,Xiaoxu Teng 국제구조공학회 2021 Steel and Composite Structures, An International J Vol.40 No.6

By using differential quadrature method (DQM), forced vibrational behavior of a porous functionally graded (FG) cylindrical scale-dependent shell in thermal environment and under a moving point load having constant velocity has been researched. Within the micro-size shell, porosities exist with even or uneven distributions. Accordingly, the material properties of the micro-size shell rely on porosities and may be defined utilizing refined power-law functions. Strain gradients have been incorporated because of the existence of size effects at micro scale. Established governing equations based on first-order shell theory have been arranged in Laplace form. Next, time responses of the micro-size shell have been calculated accomplishing inverse Laplace transform technique together with differential quadrature method (DQM). It may be understood that forced vibrational behaviors of micro-size shells are dependent on the load speed, strain gradient factor, pore volume, material gradation and temperature variation.

Examining the performance of PAI/ZnO synthesized with diamine and nano particles

Jianwei Shi,Xiaoxu Teng Techno-Press 2023 Advances in nano research Vol.14 No.2

A ZnO/poly (amide-imide) hybrid nanocomposite film with different weight percentages of Zinc oxide (ZnO) nanoparticles is synthesized and characterized in this paper. A two-step reaction successfully synthesized a new kind of heteroaromatic diamine with bulky pendant groups. In order to produce 3, 5-dinitro-3, 3-bis (4-(4-Nitrophenoxy) phenyl) -2- benzofuran-1-one, 3, 3'-bis (4-hydroxyphenyl) benzofuran-1-one and 3'-bis (4-hydroxyphenyl) benzofuran-1-one were combined with 3'-bis (3-hydroxyphenyl) benzofuran-1-one. The obtained dinitro was then reduced by zinc dust and hydrochloric acid. The reaction of 4, 4^* carbonyl diphthalic anhydride with amino acid L-alanine in acetic acid leads to the production of very high yields of chiral diacid monomer. As a result of the direct polymerization of these monomers, new optically active polymers were formed (amide-imide). In order to synthesize poly (amide-imide)/ZnO nanocomposites with different weight percentages (2, 4, 6, 8, and 10%), PAI and ZnO nanoparticles were combined using ultrasonication SEM, Fourier transform infrared spectroscopy, X-ray diffraction and thermal gravimetry were used to characterize the PAI films.

Transportation and Deposition of Modern Sediments in the Southern Yellow Sea

Shi, Xuefa,Chen, Zhihua,Cheng, Zhenbo,Cai, Deling,Bu, Wenrui,Wang, Kunshan,Wei, Jianwei,Yi, Hi-Il The Korean Society of Oceanography 2004 Journal of the Korean Society of Oceanography Vol.39 No.1

Based on the data obtained under the China-Korea joint project (1997-2001) and historic observations, the distribution, transportation and sedimentation of sediment in the southern Yellow Sea (SYS) are discussed, and the controversial formation mechanism of muddy sediments is also explored. The sediment transport trend analysis indicates that the net transport direction of sediment in the central SYS (a fine-grained sediment deposited area) points to $123.4^{\circ}E,\;35.1^{\circ}N$, which is a possible sedimentation center in the central SYS. The sediment transport pattern is verified by the distribution of total suspended matter (TSM) concentration and ${\delta}^{13}C$ values of particulate organic carbon (POC), the latter indicates that the bottom water plays a more important role than the surface water in transporting the terrigenous material to the central deep-water area of the SYS, and the Yellow Sea circulation is an important control factor for the sediment transport pattern in the SYS. The carbon isotope signals of organic matter in sediments indicate that the Shandong subaqueous delta has high sedimentation rate and the deposited sediments originate mainly from the modern Yellow River. The terrigenous sediments in deep-water area of the SYS originate mainly from the old Yellow River and the modern Yellow River, and only a small portion originates from the modern Yangtze River. The analytical results of TSM and stable carbon isotopes are further confirmed by another independent tracer of sediment source, polycyclic aromatic hydrocarbons (PAHs). Five light mineral provinces in the SYS can be identified and they indicate inhomogeneity in sources and sedimentary environment. The modern shelf sedimentary processes in the SYS are controlled by shelf dynamic factors. The muddy depositional systems are produced in the shelf low-energy environments, which are controlled by some meso-scale cyclonic eddies (cold eddies) in the central SYS and the area southwest of the Cheju Island. On the contrary, an anticyclonic muddy depositional system (warm eddy sediment) appears in the southeast of the SYS (the area northwest of the Cheju Island). In this study, we give the cyclonic and anticyclonic eddy sedimentation patterns.

Transportation and Deposition of Modern Sediments in the Southern Yellow Sea

Xuefa Shi,Zhihua Chen,Zhenbo Cheng,Deling Cai,Wenrui Bu,Kunshan Wang,Jianwei Wei,Hi-Il Yi 한국해양과학기술원 2004 Ocean science journal Vol.39 No.1

Finite-time Event-triggered Extended Dissipative Control for a Class of Switched Linear Systems

Hui Gao,Kaibo Shi,Hongbin Zhang,Jianwei Xia 제어·로봇·시스템학회 2021 International Journal of Control, Automation, and Vol.19 No.8

This paper investigates the problem of event-triggered finite-time extended dissipative control for a class of switched linear systems. We propose a novel event-triggered method that allows frequent system switching over an event-triggered interval, which is different from the previous work that only one switching happened over the event-triggered interval. By average dwell time and a novel controller-mode-dependent Lyapunov function method, we give sufficient conditions for finite-time extended dissipative analysis of the closed-loop switched linear system. LMIs are used for the design of the controller. Finally, numerical examples are given to illustrate the effectiveness of the proposed method.

Tribological properties of Ti-4Si-xZr-yY2O3/ 5TiO2 Composites Prepared by High-Energy Milling,Cold Pressing and Sintering

Vitus Mwinteribo Tabie,Xiaodong Shi,Jianwei Li,Chengbin Cai,Xiaojing Xu 한국정밀공학회 2019 International Journal of Precision Engineering and Vol.20 No.11

In the present study, tribological properties of Ti–4Si–xZr–yY2O3/5TiO2 were investigated. Four composites; Ti–4Si/5TiO2, Ti–4Si–1.3Zr/5TiO2, Ti–4Si–0.3Y2O3/5TiO2 and Ti–4Si–1.3Zr–0.3Y2O3/5TiO2 were fabricated by high-energy milling and cold pressing method. The composites showed enhanced wear and friction resistance against Si3N4 spheres counterface. The hardness and wear resistance of the composite increased with the addition of rare earth and Zirconium. Ti–4Si–1.3Zr–0.3Y2O3/5TiO2 composite has the smallest wear scar (222 μm) showing good wear resistance. Fatigue wear, supplemented by abrasive, oxidative and adhesive wears were identified as the predominant wear mechanisms. The study also found that rare earth Y2O3 can significantly improve the wear resistance of composites as it reduces the friction coefficient of Ti–4Si–1.3Zr/5TiO2 composite by about 25%.

The effect of crash pulse on occupant injury in frontal coach collisions

Sun Tingting,Xiong Xin,Zheng Zhuan,Shi Xiaolong,Fan Jianwei 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.11

The purpose of this study is to reveal the effect of different acceleration curves on occupant injury risk in the frontal collision of coaches. Based on characteristics of frontal crash acceleration curves, the influence of characteristic parameters on occupant injury was studied using a two-factor variance analysis method. The finite element-rigid body coupling method was used to establish a coupled simulation for the dummy and the sled and evaluate differences in the effects on occupant injury between the acceleration curves of four different coaches and the acceleration envelope of the ECE R80 standard. Results indicate that the upper limit of the simplified curve has the greatest influence on occupant injury and it displays a positive correlation. The acceleration curve stipulated by ECE R80 is too idealized, which may lead to inadequacies in safety protection capability in vehicle and seat design.