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.

Off-grid direction-of-arrival estimation for wideband noncircular sources

Xiaoyu Zhang1,Haihong Tao,Ziye Fang,Jian Xie 한국전자통신연구원 2023 ETRI Journal Vol.45 No.3

Researchers have recently shown an increased interest in estimating the direction-of-arrival (DOA) of wideband noncircular sources, but existing studies have been restricted to subspace-based methods. An off-grid sparse recovery-based algorithm is proposed in this paper to improve the accuracy of existing algorithms in low signal-to-noise ratio situations. The covariance and pseudo covariance matrices can be jointly represented subject to block sparsity constraints by taking advantage of the joint sparsity between signal components and bias. Furthermore, the estimation problem is transformed into a single measurement vector problem utilizing the focused operation, resulting in a significant reduction in computational complexity. The proposed algorithm's error threshold and the Cramer–Rao bound for wideband noncircular DOA estimation are deduced in detail. The proposed algorithm's effectiveness and feasibility are demonstrated by simulation results.

A New ent-Kaurane type Diterpenoid Glycoside from Inula japonica Thunb

Jiang Jiang Qin,Jia Xian Zhu,Wei Dong Zhang1,2,Yan Zhu,Jian Jun Fu,Xiao Hua Liu,Hui Zi Jin 대한약학회 2009 Archives of Pharmacal Research Vol.32 No.10

A new ent-kaurane type diterpenoid glycoside, 17-O-β-D-glucopyranosyl-16α-ent-kauran-19-oic acid (1), together with 17-hydroxy-16α-ent-kauran-19-oic acid (2), 16α,17-dihydroxyl-ent-kauran-19-oic acid (3), and 16α-hydroxy-17-acetoxy-ent- kauran-19-oic acid (4) were isolated from the aerial parts of Inula japonica Thunb. The structure of 1 was determined mainly by use of 1D and 2D NMR spectroscopic techniques including HSQC, 1H-1H COSY, HMBC, and NOESY. In addition, 4 exhibited significant inhibitory activity on NO production in LPS-stimulated RAW264.7 cells with IC50 value of 14.3 μg/mL.

Individual Effect of Matric Suction on Soil Microstructure and Hydraulic Conductivity

Jian Zhang,Shihua Zhang,Tibing Xu 대한토목학회 2020 KSCE JOURNAL OF CIVIL ENGINEERING Vol.24 No.5

The reduction of the soil micro-pore volume and hydraulic conductivity by unsaturated infiltration have been widely recognized. Among other factors responsible for this phenomenon, matric suction plays a key role in such a process. It is quite difficult to figure out the individual contribution of matric suction on soil microstructure and hydraulic conductivity change during unsaturated infiltration due to the complexity of the infiltration process. In this paper, individual effect of matric suction on soil microstructure and hydraulic conductivity was quantified using lab tests and Kozeny-Carman equation. A series of experiments with different matric suction actions were performed using unsaturated triaxial testing apparatus without axial stress. Nuclear magnetic resonance test equipment was used to quantify the imperceptible effect of the matric suction action on the soil micro-pore change. Results show that: under different matric suction actions, porosity of the specimens decreases gradually with the increase of matric suction and the matric suction action frequency. Soil is gradually compressed under matric suction action. Hydraulic conductivity of remolded silty clay was predicted based on the test data and Kozeny-Carman equation. With the increase of matric suction and the matric suction action frequency, hydraulic conductivity can be decreased by up to 25%.

Discrete Poisson Noise Logging Image Repair Based on Schatten Matrix Operator

Zhang Jian,Yang Jie,Zhang bin 보안공학연구지원센터 2016 International Journal of Multimedia and Ubiquitous Vol.11 No.3

In order to solve the problem that the present logging image reconstruction algorithm has certain staircase effect and ring effect during the discrete Poisson noise image repair process, a noise reduction algorithm based on Schatten matrix operator for discrete Poisson logging image is proposed in this article. Specifically, Schatten norm matrix of Hessian operator is adopted to estimate each pixel value of the image, and meanwhile the non-quadratic regularization function is adopted to eliminate the staircase effect; then Poisson measurement model is integrated with Schatten regularization function to construct the minimum objective function; then norm proximal mapping estimation algorithm is defined and is adopted to decouple the data fidelity item and the regularization matrix in the objective function, thus to recover the image. The simulation result shows: compared with present denoising technology, the algorithm proposed in this article has better repair effect and greater similarity in the aspect of processing the discrete Poisson noise.

Performance investigation of nanoscale thermal cloak by the perforated silicon film

Zhang Jian,Zhang Haochun,Zhang Dong,Sun Wenbo,Li Yiyi 한국물리학회 2022 Current Applied Physics Vol.35 No.-

In recent years, nanoscale thermal cloak, as a representative of nanoscale heat flux regulation devices, has attracted a lot of attention from researchers. However, the existing design methods are relatively complicated and all adopt constant temperature boundaries, the temperature changes constantly in the real environment, which greatly hinders its engineering applications. In this paper, inspired by phonon localization theory, we construct a nanoscale thermal cloak by a perforated silicon membrane and evaluate its cloaking performance and dynamic response. Results show that when the perforated area is fixed, the more the number of holes, the better the cloaking performance. In addition, the nanoscale thermal cloak still exhibits good cloaking performance in the dynamic environment. Finally, the cloaking mechanism is analyzed by calculating the phonon density of states (PDOS) and mode participation rate (MPR), and the reduction of thermal conductivity in the functional region is attributed to phonon localization.

Object Recognition System of Sonar Image Based on Multiple Invariant Moments and BP Neural Network

Jianning Han,Peng Yang,Lu Zhang 보안공학연구지원센터 2014 International Journal of Signal Processing, Image Vol.7 No.5

Object Recognition System of Sonar Image plays an important role in the field of underwater defense According to pattern recognition theory, principle processes of a typical object recognition system is introduced . To achieve robust performance, image de-noising, sharpening, binary transformation, edge detection and other image processing techniques are discussed . The paper presents a novel object recognition system using multiple invariant moments as the main feature of the object, and the detected feature is trained by BP neural network so that the classification error can be minizied. Finally, we implemented the proposed approach by visual air plane recognition, the experimental results demonstrates the robustness and efficiency of the presented approach.

ROOM-TEMPERATURE FERROMAGNETISM IN SnO 2 NANOFIBERS AND NANOTUBES PREPARED BY ELECTROSPINNING

JIAN-GUO ZHAO,WEI-YING ZHANG,ZHAO-JUN LIU,ZHONG-LI LIU,YA-JUAN ZHANG,ER-QING XIE,XIU-YUN AN,YONG-FENG CHEN,CHANG-YOU ZHANG 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2014 NANO Vol.9 No.2

SnO 2 nano¯bers and nanotubes were synthesized by electrospinning method. Magnetizationmeasurement indicates that the SnO 2 nano¯bers and nanotubes annealed in air at 500?C exhibitthe room-temperature ferromagnetism and the ferromagnetism of nanotubes is stronger than thenano¯bers. Selected area electron di®raction, X-ray di®raction and Raman measurements showthat all the samples possess a typical rutile structure and no other impurity phases are observed. The results of the Raman spectra also indicate that there are lots of defects existing in thefabricated samples. The observed room-temperature ferromagnetism in SnO 2 nano¯bers andnanotubes possibly originates from oxygen vacancies. The ¯eld cooled (FC) and zero-¯eld-cooled(ZFC) magnetization curves indicate that the Curie temperature T C is above 300 K.

Modeling and Verifying of CPS Component Services Based on Hybrid Automata

Jianning Zhang,Guanquan Zhang,Rongjie Yan,Yi Zhu,Xingjun Qi 보안공학연구지원센터 2014 International Journal of Multimedia and Ubiquitous Vol.9 No.6

The Role of Wheat Germ Agglutinin in the Attachment of Pseudomonas sp. WS32 to Wheat Root

Jian Zhang,Liyuan Meng,Yuanyuan Cao,Huiping Chang,Zhongyou Ma,Leni Sun,Ming Zhang,Xinyun Tang 한국미생물학회 2014 The journal of microbiology Vol.52 No.12

Wheat germ agglutinin (WGA), which is secreted on thesurface of wheat root, has been defined as a protein that reversiblyand non-enzymatically binds to specific carbohydrates. However, little attention has been paid to the functionof WGA in the attachment of bacteria to their host plants. The aim of this study was to investigate the role of WGA inthe attachment of Pseudomonas sp. WS32 to wheat roots. Wheat roots were initially treated with double-distilled water,WGA-H (WGA solution that was heated at 100°C for 15 min)and WGA, independently. Subsequently, the roots were coincubatedwith cell solutions (109 cells/ml). A dilution platemethod using a solid nutrient medium was employed to determinethe adsorption of WS32 to wheat roots. WGA waslabeled with fluorescein isothiocyanate and detected usingthe fluorescent in situ hybridization (FISH) technique. Thenumber of adsorptive WS32 cells on wheat roots was significantlyincreased when the wheat roots were pretreatedwith WGA, compared with the control treatment (p = 0.01). However, WGA-H failed to increase the amount of bacterialcells that attached to the wheat roots because of the lossof its physiological activity. The FISH assay also revealedthat more cells adhered to WGA-treated wheat roots than tocontrol or WGA-H-treated roots. The results indicated thatWGA can mediate Pseudomonas strain WS32’s adherenceto wheat seedling roots. The findings of this study provide abetter understanding of the processes involved in plant-microbe interactions.