First Principles Investigation of the Mechanical, Thermodynamic and Electronic Properties of FeSn5 and CoSn5 Intermetallic Phases under Pressure

Wenming Sun,Jing Liu,Hong Wang,Zhenwei Zhang,Liang Zhang,Yuxiang Bu 한국물리학회 2017 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.70 No.4

For guidance for developing Fe/Co-Sn-based anode materials for lithium-ion batteries, the mechanical, thermodynamic and electronic properties of FeSn5 and CoSn5 intermetallic phases under pressures ranging from 0 to 30 GPa have been investigated systematically using first-principles total-energy calculations within the framework of the generalized gradient approximation. The pressure was found to have significant effects on the mechanical, thermodynamic and electronic properties of these compounds. In the selected pressure range, CoSn5 has a more negative formation enthalpy than FeSn5. Based on the calculated elastic constants, the bulk modulus, shear modulus, and Young’s modulus were determined via the Viogt-Reuss-Hill averaging scheme. The variations of specific heats at constant volume for FeSn5 and CoSn5 in a wide pressure (0 - 30 GPa) and temperature (0 - 1000 K) range are also predicted from phonon density of states calculation. The calculated results suggested that both FeSn5 and CoSn5 are mechanically stable at pressure from 0 to 30 GPa. FeSn5 is dynamically stable at pressure up to, 30 GPa, at least, however, CoSn5 is dynamically stable no higher than 15 GPa.

Assessment of deformations and internal forces in the suspension bridge under eccentric live loads: Analytical algorithm

Wenming Zhang,Xiaofan Lu,Jiaqi Chang,Genmin Tian,Lianfeng Xia 국제구조공학회 2021 Structural Engineering and Mechanics, An Int'l Jou Vol.80 No.6

Suspension bridges bear large eccentric live loads in rush hours when most vehicles travel in one direction on the left or right side of the bridge. With the increasing number and weight of vehicles and the girder widening, the eccentric live load effect on the bridge behavior, including bending and distortion of the main girder, gets more pronounced, even jeopardizing bridge safety. This study proposes an analytical algorithm based on multi-catenary theory for predicting the suspension bridge responses to eccentric live load via the nonlinear generalized reduced gradient method. A set of governing equations is derived to solve the following unknown values: the girder rigid-body displacement in the longitudinal direction; the horizontal projection lengths of main cable’s segments; the parameters of catenary equations and horizontal forces of the side span cable segments and the leftmost segments of middle span cables; the suspender tensions and the bearing reactions. Then girder’s responses, including rigid-body displacement in the longitudinal direction, deflections, and torsion angles; suspenders’ responses, including the suspender tensions and the hanging point displacements; main cables’ responses, including the horizontal forces of each segment; and the longitudinal displacement of the pylons’ tower top under eccentric load can be calculated. The response of an exemplar suspension bridge with three spans of 168, 548, and 168 m is calculated by the proposed analytical method and the finite element method in two eccentric live load cases, and their results prove the former’s feasibility. The nonuniform distribution of the live load in the lateral direction is shown to impose a greater threat to suspension bridge safety than that in the longitudinal direction, while some other specific features revealed by the proposed method are discussed in detail.

Behaviors of RPC-filled double skin steel tubular stub columns under axial compression loading

Wenming Hao,Qifang Xie,Yun Zhang,Dunfeng Xu,Zhitian Zhang 국제구조공학회 2021 Steel and Composite Structures, An International J Vol.40 No.6

This paper presents the compressive behaviors of RPC-filled double skin steel tubular (RFDST) stub columns. Six RFDST stub column specimens, with different hollow ratios and constraint coefficients, were tested under axial compression loading. The compressive behaviors, such as failure mode, strength and ductility, were analyzed. It is found that the failure mode of RPC filled steel tube (RFST) stub column is shear failure, while RFDST stub columns are waist drum failure. The load deformation curves of RFDST specimens with different hollow ratio and constraint coefficient show different characteristics. RFDST specimens exhibit high bearing capacity and good ductility. Based on the test results of existing RFDST stub columns, a design formula for predicting the ultimate bearing capacity is given. A finite element model is also presented to analyze the compressive behaviors, and good agreement is obtained. The influences of hollow ratio and constraint coefficient on the ultimate bearing capacity are discussed.

Concealment of iris features based on artificial noises

Wenming Jiao,Heng Zhang,Qiyan Zang,Weiwei Xu,Shuaiwei Zhang,Jian Zhang,Hongran Li 한국전자통신연구원 2019 ETRI Journal Vol.41 No.5

Although iris recognition verification is considered to be the safest method of biometric verification, studies have shown that iris features may be illegally used. To protect iris features and further improve the security of iris recognition and verification, this study applies the Gaussian and Laplacian mechanisms and to hide iris features by differentiating privacy. The efficiency of the algorithm and evaluation of the image quality by the image hashing algorithm are selected as indicators to evaluate these mechanisms. The experimental results indicate that the security of an iris image can be significantly improved using differential privacy protection.

Preparation of Al2O3/AZ91D Mg Interpenetrating Composites Using Lost Foam Casting Combined with Layered Extrusion Forming

Wenming Jiang,Guangyu Li,Feng Guan,Junwen Zhu,Dongping Zhang,Zitian Fan 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.4

A novel method named lost foam casting (LFC) process combined with layered extrusion forming (LEF) technology wasproposed to prepare the Al2O3/AZ91D Mg interpenetrating composites, and the microstructural characteristics, thermalexpansion performance and wear resistance of the Al2O3/AZ91D interpenetrating composites were investigated in this work. The results indicated that a superior bonding between AZ91D magnesium alloy and Al2O3porous ceramic was achieved. The Al2O3/AZ91D interpenetrating composites exhibited obvious improvements in the thermal expansion performance andthe wear resistance compared to the AZ91D alloy. Therefore, the LFC process combined with the LEF technology providesa promising method for the preparation of the Al2O3/AZ91D interpenetrating composites.

Singularly perturbed nonlinear Dirichlet problems involving critical growth

Byeon, Jaeyoung,Zhang, Jianjun,Zou, Wenming Springer-Verlag 2013 Calculus of variations and partial differential eq Vol.47 No.1

Performance and Mechanism Analysis of Succinate Production under Different Transporters in Escherichia coli

Xiaozhan Li,Wenming Zhang,Mingke Wu,Fengxue Xin,Weiliang Dong,Hao Wu,Min Zhang,Jiangfeng Ma,Min Jiang 한국생물공학회 2017 Biotechnology and Bioprocess Engineering Vol.22 No.5

Succinic acid is a platform chemical with potential for bio-based synthesis. However, the production of bio-based succinate is limited because of insufficient succinate efflux capacity in the late stage of fermentation. In the present study, three different transporters, which have been reported to be responsible for C4-dicarboxylates transport, were employed for investigation of the transport capacity of succinate in Escherichia coli. After engineered strains were constructed, the fermentative production of succinic acid was studied in serum bottles and 3 L of fermentor. The results demonstrated that engineered strain showed better efflux capacity than control strain under high concentration of succinate. The highest production of succinate was 68.66 g/L, while the NCgl2130 transporter may be the best candidate for succinate export in E. coli. Further research showed that the expression levels and relative enzyme activities involved in the metabolic pathway all increased markedly, and the maximum activities of PPC, PCK, PYK, and MDH increased by 1.50, 1.38, 1.28, and 1.27-fold in recombinant E. coli AFP111/pTrc99a- NCgl2130, respectively. Moreover, the maximum level of intracellular ATP increased by 23.79% in E. coli AFP111/ pTrc99a-NCgl2130. Taken together, these findings indicated that engineered transporters can improve succinate production by increasing key enzyme activities and intracellular ATP levels. To the best of thew authors’ knowledge, this is the first report on a mechanism to improve succinate production by engineered transporters. This strategy set up a foundation for improving the biosynthesis of other C4-dicarboxylates, such as fumaric acid and malic acid.

The Role of Cotton Fibers in Mediating the Energy Band Structure of TiO2-BiFeO3 Heterojunction in Cotton-TiO2-BiFeO3 Composites for Its Photodegradation of Congo Red Dyes and Photoreduction of Cr(VI) Ions

Wendou Chen,Hui Zhang,Wenming Li,Li Mengyang,Hailiang Wu,Ningtao Mao 한국섬유공학회 2022 Fibers and polymers Vol.23 No.8

TiO2-based heterojunctions loaded on organic templates (e.g., cotton fabrics) are found to have improvedphotocatalytic activities. However, the role of fibrous templates on their photocatalytic properties has hardly beeninvestigated. In this paper, TiO2-BiFeO3 heterojunction (TiO2-BFO) was immobilized on cotton fibers in hydrothermalprocess. The structures of both TiO2-BFO and cotton-TiO2-BFO composites (C-TiO2-BFO) were systematicallycharacterized. Their photodegradation of Congo red (CR) dyes and photoreduction of Cr(VI) ions under visible lights wereanalyzed. Their active species were identified via trapping experiments and electron spin resonance spectra, and their energyband structures were examined via the density functional theory (DFT). Experimental results indicated that in comparisonwith the TiO2 loaded cotton fibers (C-TiO2), the superior photocatalytic properties of C-TiO2-BFO were attributed to itssubstitutional doping of C/O of cotton into BFO in the TiO2-BFO, which resulted in the narrowed band-gap, the strong lightharvestingcapability, and the fast separation of photoinduced electron-hole pairs of C-TiO2-BFO. Importantly, DFTcalculations testified that the energy band structure of TiO2-BFO could be mediated by constructing the built-in electric fieldbetween TiO2-BFO and cellulose cotton. The hole species were the dominant radicals in the C-TiO2-BFO, while 1O2 specieswere the main radicals in the TiO2-BFO in CR photodegradation process.

Stability region of floating intermediate support in a shaft system with multiple universal joints

Yiting Kang,Yanhua Shen,Wenming Zhang,Jue Yang 대한기계학회 2014 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.28 No.7

A floating intermediate support is designed to reduce kinematic and dynamic fluctuations caused by the change of joint angles in ashaft system with multiple universal joints. The dynamic equation of the shaft system is derived via the principle of virtual work, whichsuggests the angular displacement of the input shaft is the only independent variable. A drive shaft system used in an articulated dumptruck is taken as an example to analyze the sensitivities of shaft speed and input torque of the system about structural parameters andsystem variables, which proves the effectiveness of floating support to attenuate the kinematic and dynamic fluctuations of the shaft system. The stability region of floating support aimed at shaft speed and input torque of the system keeping relatively stable is obtained bysetting proper upper limits of objectives, and the analysis results are verified by dynamic simulation in MapleSim platform, which ishelpful to decide proper stiffness and damping or determine an optimum control strategy for floating angle of support in design.

Dynamic characteristics and test analysis of a new drilling downhole tool with anti-stick-slip features

Jia-lin Tian,Tangjia Zhang,Liming Dai,Wenming Cheng,Lin Yang,Chang-fu Yuan 대한기계학회 2018 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.32 No.10

A key problem in drill string dynamics is the stick–slip in deep and large displacement horizontal wells that may lead to the decline in drilling performance or cause tool failure, which may eventually cause underground accidents. Therefore, the research on the production safety, ROP, and increased efficiency in relation to stick–slip theory and practical stick–slip reduction is highly relevant, especially in complex drilling conditions. On this basis, this study takes the new constant torque tool as the engineering background and establishes the working mechanism analytical model of stick–slip reduction and torque constant. A helical dynamic model is established to solve the core problem of the constant torque tool. Then, the differential equation of the helical spline drive motion is deduced. The motion of the helical spline mandrel is calculated, and its analytical results are compared with simulation results. Findings show that the laws of angular displacement, angular velocity, axial displacement, and axial velocity are consistent with the simulation results when the helical spline mandrel moves up or down. The established theoretical model can promote the development of drill string dynamics in new drilling conditions. Moreover, the proposed designing methods can provide new ideas for the development of a stick–slip reduction tool. The results can be further used as reference for key parameter determination and stick–slip reduction technology optimization.