Wettability and corrosion of molten sodium carbonate on aluminum-silicon refractory

Zhigang Xu,Yi Xia,Yizhao Mu 한양대학교 청정에너지연구소 2023 Journal of Ceramic Processing Research Vol.24 No.6

The corrosion and infiltration of refractory by chemical waste liquid rich in alkali ions such as potassium and sodiumare the main cause of material damage. Their service life varies with the material systems. In this work, threekinds of aluminum-silicon refractories were prepared by using alumina, mullite, andalusite and clay as raw materials. Staticcrucible method was used to carry out alkali corrosion test at 900 ℃, and Na2CO3 was used as corrosive agent. The phasesand microstructures of the residual crucibles were examined by means of X-ray diffraction (XRD) and scanning electronmicroscope (SEM). The wetting process of molten Na2CO3 on refractory was detected by high temperature contact anglemeasurement system. The corrosion and infiltration resistance of refractories were discussed based on their wettability. Theresults show that corundum-mullite system has weak ability to resist corrosion and infiltration of the molten Na2CO3. Bycontrast, high-purity mullite system has better performance. The mullite transformed from andalusite can improve its infiltrationresistance. The infiltration of molten Na2CO3 into refractory is related to its wetting ability, they both determine thedamage degree of refractories.

Antibiotic resistance, biochemical typing, and PFGE typing of Bifidobacterium strains commonly used in probiotic health foods

Xu, Feili,Wang, Junping,Guo, Yunchang,Fu, Ping,Zeng, Huawei,Li, Zhigang,Pei, Xiaoyan,Liu, Xiumei,Wang, Shuo 한국식품과학회 2018 Food Science and Biotechnology Vol.27 No.2

This study firstly analyzed the antibiotic resistance, biochemical typing, and pulsed-field gel electrophoresis typing of 45 Bifidobacterium strains commonly used in health foods. Most strains were resistant to antibiotics but their antibiotic resistance rates were not high: Fos (56.52%), TET (43.48%), CRO (21.74%), AMC (15.22%), GEN (13.04%), RIF (10.87%), CHL (8.7%), CTX (6.52%), VAN (4.35%), and ERY (4.35%). The 45 strains could be divided into 14 pulsed-field gel electrophoresis types, of which the strain numbers of six pulsed-field gel electrophoresis types were more than one. All the Bifidobacterium strains could be divided into nine types by API50CHL biochemical identification. The same species displayed same biochemical typings, expect for B. animalis. Furthermore, the results confirmed that the same pulsed-field gel electrophoresis-type strains had closer antibiotic resistance patterns, and the same biochemical-type strain also had similar antibiotic resistance patterns.

Energy efficiency task scheduling for battery level-aware mobile edge computing in heterogeneous networks

Zhigang Xie,Xin Song,Jing Cao,Siyang Xu 한국전자통신연구원 2022 ETRI Journal Vol.44 No.5

This paper focuses on a mobile edge-computing-enabled heterogeneous network. A battery level-aware task-scheduling framework is proposed to improve the energy efficiency and prolong the operating hours of batterypowered mobile devices. The formulated optimization problem is a typical mixed-integer nonlinear programming problem. To solve this nondeterministic polynomial (NP)-hard problem, a decomposition-based taskscheduling algorithm is proposed. Using an alternating optimization technology, the original problem is divided into three subproblems. In the outer loop, task offloading decisions are yielded using a pruning search algorithm for the task offloading subproblem. In the inner loop, closed-form solutions for computational resource allocation subproblems are derived using the Lagrangian multiplier method. Then, it is proven that the transmitted power-allocation subproblem is a unimodal problem; this subproblem is solved using a gradient-based bisection search algorithm. The simulation results demonstrate that the proposed framework achieves better energy efficiency than other frameworks. Additionally, the impact of the battery level-aware scheme on the operating hours of battery-powered mobile devices is also investigated.

Cooperative encryption over backscatter: Secure green communication for two-way energy harvesting relay networks

Siyang Xu,Xin Song,Suyuan Li,Jing Cao,Jiahui Zhu,Zhigang Xie 한국통신학회 2023 ICT Express Vol.9 No.3

This paper focuses on the design of a novel cooperative jamming strategy and resource allocation scheme in two-way energy harvesting (EH) relay networks. For solving the security vulnerability challenges, a backscatter jamming strategy is proposed by leveraging the information signals as the carrier, which can degrade the eavesdropping link without extra energy consumption, delay and strict synchronization requirement. Based on the above design, we formulate the secure energy efficiency (SEE) maximization problem by jointly optimizing the transmission powers of two sources, two different power splitting (PS) factors and time allocation factor. Although the resulting optimization problem is highly non-convex due to fractional objective function and multivariate coupling, an iterative algorithm is developed to convert the original problem into a tractable version and obtain the resource allocation solutions. Simulation results show that the achievable SEE of the proposed scheme is better than other conventional schemes.

False diffusion in numerical simulation of combustion processes in tangential-fired furnace

Xuchang Xu,Zhigang Wang,Yuqun Zhuo,Changhao Zheng 대한기계학회 2007 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.21 No.11

Numerical simulation serves as one of the most important tools for analyzing coal combustion in Tangentially Fired Furnaces (TFF) with NUMERICAL FALSE DIFFUSION as one key problem that degrades the simulation accuracy, especially for complex flow patterns. False diffusion often completely compromises the accuracy, leading to erroneous predictions. This paper reviews various methods to reduce the numerical diffusion. In computational fluid dynamics (CFD), false diffusion originates from a truncation error of the Taylor series approximation of the derivative and multidimensional discretization effects. Higher-order upwind convective schemes were designed to reduce truncation errors, while grid line adjusting methods were developed to reduce crossflow diffusion. This paper compares numerical and experimental results for isothermal flows to evaluate these methods. Results with the standard upwind scheme in a rectangular Cartesian mesh are compared with results in body-fitted meshes for comprehensive combustion processes in a TFF. Analysis of the false diffusion effect in the x, y, z directions and the artificial viscosity distribution in a rectangular mesh shows where the false diffusion overtakes the real physical diffusion and where the mesh must be refined or grid line must be adjusted to improve TFF combustion simulations.

Comparative transcriptome analysis of three chrysanthemums provides insights into flavonoid and terpenoid biosynthesis

Wang Xu,Zhang Jingjing,Liu Zhige,Wang Shuaibin,Huang Bisheng,Hu Zhigang,Liu Yifei 한국식물학회 2021 Journal of Plant Biology Vol.64 No.5

Chrysanthemum indicum var. aromaticum is an important resource plant for breeding excellent aromatic varieties of ornamental and medicinal chrysanthemums. However, the biosynthesis and regulation mechanisms of typically aromatic ingredients in C. indicum var. aromaticum are poorly understood, which restricted the utilization of this plant. Here, the transcriptome of C. indicum var. aromaticum was investigated and comparative analysis was conducted with the other two closely related chrysanthemum taxa C. indicum and C. nankingense. The global transcriptome profiles showed clear difference of gene expression patterns between the three chrysanthemums, of which 52 flavonoid biosynthesis-associated genes, 157 transcription factors, and 24 flavonoid Uridine diphosphate (UDP) -glucuronosyl and -glucosyltransferase genes were significantly differentially expressed. Furthermore, 22 differential expression genes (DEGs) in relation to the terpenoid backbone biosynthesis and 183 DEGs related to terpenoid diversification were identified. Of which, 14 genes involved into TS/CYP gene cluster showed higher expression in CIA than those in CI or CN. These results increased our understanding of flavonoid diversification and aromatic ingredients accumulation in plants, and will also help improve resource conservation and sustainable utilization of the important resource plant C. indicum var. aromaticum.

Energy Efficiency Maximization for Energy Harvesting Bidirectional Cooperative Sensor Networks with AF Mode

( Siyang Xu ),( Xin Song ),( Lin Xia ),( Zhigang Xie ) 한국인터넷정보학회 2020 KSII Transactions on Internet and Information Syst Vol.14 No.6

This paper investigates the energy efficiency of energy harvesting (EH) bidirectional cooperative sensor networks, in which the considered system model enables the uplink information transmission from the sensor (SN) to access point (AP) and the energy supply for the amplify-and-forward (AF) relay and SN using power-splitting (PS) or time-switching (TS) protocol. Considering the minimum EH activation constraint and quality of service (QoS) requirement, energy efficiency is maximized by jointly optimizing the resource division ratio and transmission power. To cope with the non-convexity of the optimizations, we propose the low complexity iterative algorithm based on fractional programming and alternative search method (FAS). The key idea of the proposed algorithm first transforms the objective function into the parameterized polynomial subtractive form. Then we decompose the optimization into two convex sub-problems, which can be solved by conventional convex programming. Simulation results validate that the proposed schemes have better output performance and the iterative algorithm has a fast convergence rate.

Antibiotic resistance, biochemical typing, and PFGE typing of Bifidobacterium strains commonly used in probiotic health foods

Feili Xu,Junping Wang,Yunchang Guo,Huawei Zeng,Ping Fu,Zhigang Li,Xiaoyan Pei,Xiumei Liu,Shuo Wang 한국식품과학회 2018 Food Science and Biotechnology Vol.27 No.2

This study firstly analyzed the antibiotic resistance, biochemical typing, and pulsed-field gel electrophoresis typing of 45 Bifidobacterium strains commonly used in health foods. Most strains were resistant to antibiotics but their antibiotic resistance rates were not high: Fos (56.52%), TET (43.48%), CRO (21.74%), AMC (15.22%), GEN (13.04%), RIF (10.87%), CHL (8.7%), CTX (6.52%), VAN (4.35%), and ERY (4.35%). The 45 strains could be divided into 14 pulsed-field gel electrophoresis types, of which the strain numbers of six pulsed-field gel electrophoresis types were more than one. All the Bifidobacterium strains could be divided into nine types by API50CHL biochemical identification. The same species displayed same biochemical typings, expect for B. animalis. Furthermore, the results confirmed that the same pulsed-field gel electrophoresis-type strains had closer antibiotic resistance patterns, and the same biochemicaltype strain also had similar antibiotic resistance patterns.

Differential Evolution Algorithm Based on State Transition of Specific Individuals for Economic Dispatch Problems with Valve Point Effects

Li Xueping,Xu Jian,Lu Zhigang 대한전기학회 2022 Journal of Electrical Engineering & Technology Vol.17 No.2

Economic Dispatch problem with valve-point eff ects is a complex solution problem involving the practical constraints of equality and inequality. The paper proposes a diff erential evolution algorithm based on specifi c individuals of state transition to solve small, medium and large-economic dispatch problems with valve-point eff ects. The core of DE-STA is to use the state transition to update specifi c individuals after a diff erential evolution of the population, which improves the optimization effi ciency, robustness and accuracy of the algorithm. Moreover, a new state operator of translation transformation is adopted to improve effi ciency of state transition, which introduces individuals of information exchange. Compared with the traditional DE and other algorithms, better robustness, faster convergence speed and accuracy results of the DE-STA are demonstrated by solving small, medium and large-economic dispatch problems with valve-point eff ects related to 13-, 40- and 140-unit test system

Analytical and mathematical simulation for nonlinear stability of scale-dependent magneto-electro-elastic system

Li, Bin,Xu, Xiaojia,Hu, Zhigang,Liu, Yuzuo,Qi, Menghui,Zheng, Zengquan Techno-Press 2021 Advances in nano research Vol.11 No.4

By using differential quadrature method (DQM), a numerical investigation was provided for nonlinear stability behavior of magneto-electro-elastic (MEE) cylindrical shells at microscale. It is assumed that the cylindrical shell has been subjected to compressive loads leading to buckling phenomena in geometrically nonlinear regime. The non-uniformity of strain field has been inserted in the formulation for considering the microscale effects. The material properties of the shell are considered to be inhomogeneous with graded distribution. After solving the governing equations using DQM, it is realized that if the nanoscale shell is subjected to electrical and magnetic fields, the post-buckling path may be changed with the value of electrical voltage and magnetic potential. Also, strain gradient effects have remarkable influence on post-buckling curves and critical voltages.