Static analysis of 2D-FG nonlocal porous tube using gradient strain theory and based on the first and higher-order beam theory

Xiaozhong Zhang,Jian-Feng Li,Yan Cui,Mostafa Habibi,H. Elhosiny Ali,Ibrahim AlBaijan,Tayebeh Mahmoudi 국제구조공학회 2023 Steel and Composite Structures, An International J Vol.49 No.3

This article focuses on the study of the buckling behavior of two-dimensional functionally graded (2D-FG) nanosize tubes, including porosity, based on the first shear deformation and higher-order theory of the tube. The nano-scale tube is simulated using the nonlocal gradient strain theory, and the general equations and boundary conditions are derived using Hamilton’s principle for the Zhang-Fu’s tube model (as a higher-order theory) and Timoshenko beam theory. Finally, the derived equations are solved using a numerical method for both simply-supported and clamped boundary conditions. A parametric study is performed to investigate the effects of different parameters, such as axial and radial FG power indices, porosity parameter, and nonlocal gradient strain parameters, on the buckling behavior of the bi-dimensional functionally graded porous tube. Keywords: Nonlocal strain gradient theory; buckling; Zhang-Fu’s tube model; Timoshenko theory; Two-dimensional functionally graded materials; Nanotubes; Higher-order theory.

Cross-Layer Resource Allocation in Multi-interface Multi-channel Wireless Multi-hop Networks

Wei Feng,Suili Feng,Yongzhong Zhang3,Xiaowei Xia 한국전자통신연구원 2014 ETRI Journal Vol.36 No.6

In this paper, an analytical framework is proposed forthe optimization of network performance through jointcongestion control, channel allocation, rate allocation,power control, scheduling, and routing with theconsideration of fairness in multi-channel wireless multihopnetworks. More specifically, the framework modelsthe network by a generalized network utilitymaximization (NUM) problem under an elastic link datarate and power constraints. Using the dual decompositiontechnique, the NUM problem is decomposed into foursubproblems — flow control; next-hop routing; rateallocation and scheduling; power control; and channelallocation — and finally solved by a low-complexitydistributed method. Simulation results show that theproposed distributed algorithm significantly improves thenetwork throughput and energy efficiency compared withprevious algorithms.

Comprehensive review on physical properties of supercritical carbon dioxide calculated by molecular simulation

Gaoliang Liao,Yuntao Du,Feng Zhang,Jiaqiang E 한국화학공학회 2023 Korean Journal of Chemical Engineering Vol.40 No.1

The applications of molecular simulation in supercritical carbon dioxide (S-CO2) and its mixtures are reviewed. First, an overview of physical properties of S-CO2 and CO2 models is given. Secondly, the accuracy of S-CO2 thermodynamic and transport properties calculated by different models is compared. It shows that Zhang’s model has relatively better global accuracy in calculating thermodynamic properties. EPM2, Zhang and Cygan models have similar accuracy when calculating transport properties based on equilibrium molecular simulation (EMD) method, but generally have higher deviations when calculating thermal conductivity. Therefore, EMD and non-equilibrium molecular simulation (NEMD) methods have been compared in calculating thermal conductivity. The results show that NEMD is better than EMD but the process is complicated. The structural properties are also discussed in this part. Thirdly, the applications of molecular simulation in S-CO2 binary organic, binary inorganic and multiple mixtures are reviewed. Finally, the summary and the prospect of future works are given.

Determination of Survival of Gastric Cancer Patients With Distant Lymph Node Metastasis Using Prealbumin Level and Prothrombin Time: Contour Plots Based on Random Survival Forest Algorithm on High-Dimensionality Clinical and Laboratory Datasets

Zhang, Cheng,Xie, Minmin,Zhang, Yi,Zhang, Xiaopeng,Feng, Chong,Wu, Zhijun,Feng, Ying,Yang, Yahui,Xu, Hui,Ma, Tai The Korean Gastric Cancer Association 2022 Journal of gastric cancer Vol.22 No.2

Purpose: This study aimed to identify prognostic factors for patients with distant lymph node-involved gastric cancer (GC) using a machine learning algorithm, a method that offers considerable advantages and new prospects for high-dimensional biomedical data exploration. Materials and Methods: This study employed 79 features of clinical pathology, laboratory tests, and therapeutic details from 289 GC patients whose distant lymphadenopathy was presented as the first episode of recurrence or metastasis. Outcomes were measured as any-cause death events and survival months after distant lymph node metastasis. A prediction model was built based on possible outcome predictors using a random survival forest algorithm and confirmed by 5×5 nested cross-validation. The effects of single variables were interpreted using partial dependence plots. A contour plot was used to visually represent survival prediction based on 2 predictive features. Results: The median survival time of patients with GC with distant nodal metastasis was 9.2 months. The optimal model incorporated the prealbumin level and the prothrombin time (PT), and yielded a prediction error of 0.353. The inclusion of other variables resulted in poorer model performance. Patients with higher serum prealbumin levels or shorter PTs had a significantly better prognosis. The predicted one-year survival rate was stratified and illustrated as a contour plot based on the combined effect the prealbumin level and the PT. Conclusions: Machine learning is useful for identifying the important determinants of cancer survival using high-dimensional datasets. The prealbumin level and the PT on distant lymph node metastasis are the 2 most crucial factors in predicting the subsequent survival time of advanced GC.

NUMERICAL MODELING OF VERTICAL-2D UNSTEADY FLOW AND SUSPENDED MATERIAL DISTRIBUTION

ZHANG XIAO-FENG,FENG XIAO-XIANG,CUI ZHAN-FENG 한국수자원학회 2005 한국수자원학회 학술대회 Vol.2005 No.1

Numerical study on the shear damage behavior of sandstone under normal disturbance effects

Guorui Feng,Jie Zhang,Jun Guo,Xiaoze Wen,Luyang Yu,Wenming Feng,Xincheng Mi,Xu Zhang,Zhengjun Zhang 대한토목학회 2024 KSCE Journal of Civil Engineering Vol.28 No.7

The study focused on examining the impact of initial normal stress and normal disturbance amplitude on the degradation of rock mass in a complex stress environment. Using PFC2D numerical simulation software, various experimental characteristics of rock samples were analyzed, such as strength properties, damage patterns, and stress evolution. The results revealed that: Under constant normal stress conditions, the shear strength increases with an increase in the normal stress. From microscopic analyses, the normal stress effectively compacts the particles within the rock, which prompts more particles to contribute to the shear strength of the rock. Consequently, the mechanical property of the rock was improved, and the number of cracks during the damage process also increases. The disturbance causes internal damage and destruction to the rock samples thus degrading strength, which becomes more evident as the amplitude increases. Before the peak strength, the damage effect is dominant, while after the peak strength, the contact effect combined with the damage effect contributes to the formation of the shear plane cracks and wing cracks. Besides, the stress concentration along the shear direction becomes more pronounced as the normal stress increases. These findings have valuable implications for the study of rock stability under disturbance.

Novel AgCl/Ag2SO3 Hybrids as a Visible-Light-driven Photocatalyst: Preparation, Characterization, and Degradation of Rhodamine-B and Methyl Orange

Xiang-Feng Wu,Yi-Jin Wang,Zuo-Lin Cao,Yan-Mei Feng,Hui Li,Chen-Xu Zhang,Jun-Zhang Su,Jia-Rui Zhang,Yi-Wei Wang,Kai-Yuan Wang,Guo-Wen Sun 대한화학회 2018 Bulletin of the Korean Chemical Society Vol.39 No.7

The novel AgCl/Ag2SO3 hybrids as an efficient photocatalyst had been fabricated by an in situ synthetic method. The correlations between the structure and the photocatalytic properties of the as-fabricated hybrids were analyzed. Experimental results exhibited that with increasing the amount of Ag2SO3, the degradation rate of the as-obtained samples was firstly increased and then decreased under the visible light irradiation. When the mass ratio of AgCl to Ag2SO3 was 1:2, in 30?min, it displayed the highest degradation rate of 99.2% for rhodamine-B, which was obviously higher than 46.1, 60.5, and 14.6% of pure AgCl, Ag2SO3, and TiO2 (P25), respectively. Similar results could be found in degradation of methyl orange. It had the maximum of 97.4% in 90?min, which was higher than 55.2, 48.7, and 12.7% of pure AgCl, Ag2SO3, and P25, respectively. Moreover, the as-prepared hybrids possessed the enhanced separation and transfer of photo-generated electron?hole pairs compared to the pure samples. In addition, the holes and superoxide radicals played the dominant role and the hydroxyl radicals played the secondary role during the process of photocatalytic degradation.

Enhancement of transglutaminase production in Streptomyces mobaraensis DSM 40587 by non-nutritional stress conditions: Effects of heat shock, alcohols, and salt treatments

Lili Zhang,Lanwei Zhang,Huaxi Yi,Ming Du,Yingchun Zhang,Xue Han,Zhen Feng,Jingyan Li,Yuehua Jiao,Yanhe Zhang,Chunfeng Guo 한국화학공학회 2012 Korean Journal of Chemical Engineering Vol.29 No.7

Stress-mediated bioprocess is a strategy designed to enhance biological target productivity. In this study,an attempt was made to enhance transglutaminase (TGase) production by Streptomyces mobaraensis by using different stress conditions including heat shock, alcohols and salt stress. Results showed that the effects of stress on TGase production depended on the type applied. For heat shock, TGase production (1.32 U/ml) was recorded maximum in the culture treated at 48 h post inoculation in water bath at 60 oC for 1 min. For alcohols treatment, the maximum activity of TGase (1.77 and 1.75 U/ml) was obtained when 3% methanol was added into the medium at 0 or 24 h of fermentation. However, a 3.5-fold increased production of TGase (3.8 U/ml) was observed in the medium supplemented with 0.2mol/l MgCl2 compared with the basic medium at the beginning of fermentation. In conclusion, TGase production from S. mobaraensis was improved by heat shock, methanol and salt stress treatments, MgCl2 stress was the most effective.

Numerical Investigation and Design of Cold-formed Steel Angle Columns with Complex Edges under Axial Compression

Jun-Feng Zhang,Mengmeng Feng,En-Feng Deng,Shiyun Pang 대한토목학회 2023 KSCE Journal of Civil Engineering Vol.27 No.2

Currently, cold-formed steel (CFS) is widely used in fabricated steel structures for high strength-to-weight ratio and ease for installation. However, limited research is available in the literature on the CFS angle columns with complex edges under axial compression. In this paper, the axial compressive capacity of the CFS angle columns with complex edges was numerically studied. The distortional buckling characteristics of 1008 CFS angle sections with complex edges were analyzed by finite strip software CUFSM. Detailed non-linear finite element model (FEM) was developed based on finite element program ABAQUS and verified by comparing with test results. The verification indicated that the developed FEM could well predict the ultimate strength and failure model of the specimens. Using the validated FEM, an extensive parametric study comprised of 330 models was conducted. The influences of the specimen length, the edge ratio and the limb-width ratio of the angle section on the axial compressive capacity of CFS angle columns with complex edges were evaluated. Then an improved direct strength method (DSM) was proposed based on the existing DSM. The evaluations based on tests and FEA results showed that using the modified DSM to predict the load-bearing capacity of the CFS angle columns with complex edges was feasible.

Arrays of horizontal carbon nanotubes of controlled chirality grown using designed catalysts

Zhang, Shuchen,Kang, Lixing,Wang, Xiao,Tong, Lianming,Yang, Liangwei,Wang, Zequn,Qi, Kuo,Deng, Shibin,Li, Qingwen,Bai, Xuedong,Ding, Feng,Zhang, Jin Macmillan Publishers Limited, part of Springer Nat 2017 Nature Vol.543 No.7644

<P>The semiconductor industry is increasingly of the view that Moore's law-which predicts the biennial doubling of the number of transistors per microprocessor chip-is nearing its end(1). Consequently, the pursuit of alternative semiconducting materials for nanoelectronic devices, including single-walled carbon nanotubes (SWNTs), continues(2-4). Arrays of horizontal nanotubes are particularly appealing for technological applications because they optimize current output. However, the direct growth of horizontal SWNT arrays with controlled chirality, that would enable the arrays to be adapted for a wider range of applications and ensure the uniformity of the fabricated devices, has not yet been achieved. Here we show that horizontal SWNT arrays with predicted chirality can be grown from the surfaces of solid carbide catalysts by controlling the symmetries of the active catalyst surface. We obtained horizontally aligned metallic SWNT arrays with an average density of more than 20 tubes per micrometre in which 90 per cent of the tubes had chiral indices of (12, 6), and semiconducting SWNT arrays with an average density of more than 10 tubes per micrometre in which 80 per cent of the nanotubes had chiral indices of (8, 4). The nanotubes were grown using uniform size Mo2C and WC solid catalysts. Thermodynamically, the SWNT was selectively nucleated by matching its structural symmetry and diameter with those of the catalyst. We grew nanotubes with chiral indices of (2m, m) (where m is a positive integer), the yield of which could be increased by raising the concentration of carbon to maximize the kinetic growth rate in the chemical vapour deposition process. Compared to previously reported methods, such as cloning(5,6), seeding(7,8) and specific-structure-matching growth(9-11), our strategy of controlling the thermodynamics and kinetics offers more degrees of freedom, enabling the chirality of as-grown SWNTs in an array to be tuned, and can also be used to predict the growth conditions required to achieve the desired chiralities.</P>