Characteristics, mathematical modeling and conditional simulation of crosswind layer forces on square section high-rise building

Ailin Zhang,Shi Zhang,Xiaoda Xu,Yihui Fu,Giuseppe Piccardo 한국풍공학회 2022 Wind and Structures, An International Journal (WAS Vol.35 No.6

Wind tunnel experiment was carried out to study the cross-wind layer forces on a square cross-section building model using a synchronous multi-pressure sensing system. The stationarity of measured wind loadings are firstly examined, revealing the non-stationary feature of cross-wind forces. By converting the measured non-stationary wind forces into an energetically equivalent stationary process, the characteristics of local wind forces are studied, such as power spectrum density and spanwise coherence function. Mathematical models to describe properties of cross-wind forces at different layers are thus established. Then, a conditional simulation method, which is able to ex-tend pressure measurements starting from experimentally measured points, is proposed for the cross-wind loading. The method can reproduce the non-stationary crosswind force by simulating a stationary process and the corresponding time varying amplitudes independently; in this way the non-stationary wind forces can finally be obtained by combining the two parts together. The feasibility and reliability of the proposed method is highlighted by an ex-ample of across wind loading simulation, based on the experimental results analyzed in the first part of the paper.

Effects of excessive Zn2+ ions on intrinsic magnetic and structural properties of Ni0.2Zn0.6Cu0.2Fe2O4 powder prepared by chemical coprecipitation method

Ailin Xia,Huanling Zhang 한국물리학회 2010 Current Applied Physics Vol.10 No.3

Zn(OH)2 is a kind of amphoteric compound. Therefore, for chemical coprecipitation method, the precipitation of Zn2+ ions may be incomplete if using NaOH as precipitator. In this study, single-phase powder specimens with a nominal composition Ni0.2Zn0.6Cu0.2Fe2O4 were prepared with chemical coprecipitation method, and the effects of excessive Zn2+ content (x, x = 3%, 5%, 7%, 9%) in working solution on intrinsic magnetic and structural properties were studied by vibrating sample magnetometer and X-ray diffractometer,respectively. It was found that the magnetization when Hm = 398 kA/m (5000 Oe) reached a maximum when x = 5%, and then decreased with the increase of x, which was attributed to the effect of different amount of Zn2+ in A sites on the A–B and B–B exchange interaction. Moreover, it was found that the lattice parameter was affected by the Zn2+ and Fe3+ ions due to their different ion radius to a certain extent.

Structural and magnetic properties of M-type Sr0.1Ca0.4La0.5Fe12O19 ferrites: The effects of CoxFe3-xO4 in precursor

Xiubin Zhao,Shuang Zhang,Jinsong Li,Ailin Xia,Yujie Yang 한양대학교 청정에너지연구소 2023 Journal of Ceramic Processing Research Vol.24 No.1

M-type ferrite Sr0.1Ca0.4La0.5Fe12O19 magnetic powders doped with CoxFe3-xO4 (0 ≤ x ≤ 1.25) in precursors were prepared bya ceramics process. The structure of specimens were examined by using an X-ray diffractometer. Only the magnetoplumbitephase was found in the specimens with the cobalt content (x) from 0.25 to 1.25 in precursor. The specimens exhibited a typicalhexagonal M-type structure and the particles in specimens were uniformly distributed in size. The specimen with x=1.25 hadthe maximum saturation magnetization of 67.48 emu/g, while the residual magnetization and the coercivity of the specimenwith x=1.00 reached the maximum value of 31.83 emu/g and 1270 Oe, respectively.

Design and properties analysis of total internal reflection gratings for pulse compressor at 1053 nm

Qunyu Bi,Jiangjun Zheng,Ailin Guo,Meizhi Sun,Jianpeng Wang,Fuling Zhang,Qingwei Yang,Xinglong Xie,Zunqi Lin 한국물리학회 2011 Current Applied Physics Vol.11 No.1

High-efficiency compression gratings based on total internal reflection (TIR) are promising alternatives of compressor gratings because of their high diffraction efficiency, potential high damage resistant ability,and compact structure. Dependence of the 1 order diffraction efficiencies on grating parameters is analyzed for TE- and TM-polarized incident light of 1053 nm at Littrow angle, which is calculated by using the rigorous coupled-wave analysis. A more intuitional view on the relation is offered through three-dimensional slicing figures instead of two-dimensional ones. The performances of high-efficiency gratings are compared and regarded as criteria for further choices, including spectral bandwidth, angle bandwidth, dispersion, and intensity distribution. For TE- and TM-irradiations, similar spectral bandwidth and angle bandwidth can be achieved by different grating parameters. However, the computer simulation result on the intensity distributions of the two polarized waves shows that such design should be used under the illumination of TE-polarized wave for lower intensity enhancement ratio,which is an important factor related to the gratings’ damage threshold.

Quantifying and controlling bond multivalency for advanced nanoparticle targeting to cells

Makhani Elliot Y.,Zhang Ailin,Haun Jered B. 나노기술연구협의회 2021 Nano Convergence Vol.8 No.38

Nanoparticles have drawn intense interest as delivery agents for diagnosing and treating various cancers. Much of the early success was driven by passive targeting mechanisms such as the enhanced permeability and retention (EPR) effect, but this has failed to lead to the expected clinical successes. Active targeting involves binding interactions between the nanoparticle and cancer cells, which promotes tumor cell-specific accumulation and internalization. Furthermore, nanoparticles are large enough to facilitate multiple bond formation, which can improve adhesive properties substantially in comparison to the single bond case. While multivalent binding is universally believed to be an attribute of nanoparticles, it is a complex process that is still poorly understood and difficult to control. In this review, we will first discuss experimental studies that have elucidated roles for parameters such as nanoparticle size and shape, targeting ligand and target receptor densities, and monovalent binding kinetics on multivalent nanoparticle adhesion efficiency and cellular internalization. Although such experimental studies are very insightful, information is limited and confounded by numerous differences across experimental systems. Thus, we focus the second part of the review on theoretical aspects of binding, including kinetics, biomechanics, and transport physics. Finally, we discuss various computational and simulation studies of nanoparticle adhesion, including advanced treatments that compare directly to experimental results. Future work will ideally continue to combine experimental data and advanced computational studies to extend our knowledge of multivalent adhesion, as well as design the most powerful nanoparticle-based agents to treat cancer.

Bearing capacity of H-section beam wrapped with ceramsite concrete

Xuechun Liu,Kun Meng,Ailin Zhang,Tao Zhu,Cheng Yu 국제구조공학회 2021 Steel and Composite Structures, An International J Vol.40 No.5

In this study, an H-section steel beam with circular holes in a web wrapped with ceramsite concrete (SBWCC) was studied. Static load-bearing capacity tests and finite element analysis were performed on two groups of specimens with different sections. The H-section steel and wrapped ceramsite concrete were well bonded. The load-bearing capacity of the SBWCC was 10% larger than that of the pure H-section steel beam without holes in the web, except for its dead weight. The stiffness of the SBWCC was slightly larger than that of the pure H-section steel beam without holes. The wrapped ceramsite concrete avoided the elastic local instability of the steel beam flange and web. Based on the finite element model verified by experiments, the influences of hole diameter, hole spacing, and U-shaped stirrups on the flexural capacity of the specimens were analyzed. The formulas for the load-bearing capacities and short-term stiffness of the SBWCC were proposed and verified by tests and finite element analysis.

Theoretical and experimental study on damage detection for beam string structure

Haoxiang He,Weiming Yan,Ailin Zhang 국제구조공학회 2013 Smart Structures and Systems, An International Jou Vol.12 No.3

Beam string structure (BSS) is introduced as a new type of hybrid prestressed string structures. The composition and mechanics features of BSS are discussed. The main principles of wavelet packet transform (WPT), principal component analysis (PCA) and support vector machine (SVM) have been reviewed. WPT is applied to the structural response signals, and feature vectors are obtained by feature extraction and PCA. The feature vectors are used for training and classification as the inputs of the support vector machine. The method is used to a single one-way arched beam string structure for damage detection. The cable prestress loss and web members damage experiment for a beam string structure is carried through. Different prestressing forces are applied on the cable to simulate cable prestress loss, the prestressing forces are calculated by the frequencies which are solved by Fourier transform or wavelet transform under impulse excitation. Test results verify this method is accurate and convenient. The damage cases of web members on the beam are tested to validate the efficiency of the method presented in this study. Wavelet packet decomposition is applied to the structural response signals under ambient vibration, feature vectors are obtained by feature extraction method. The feature vectors are used for training and classification as the inputs of the support vector machine. The structural damage position and degree can be identified and classified, and the test result is highly accurate especially combined with principle component analysis.

Theoretical and experimental study on damage detection for beam string structure

He, Haoxiang,Yan, Weiming,Zhang, Ailin Techno-Press 2013 Smart Structures and Systems, An International Jou Vol.12 No.3

Beam string structure (BSS) is introduced as a new type of hybrid prestressed string structures. The composition and mechanics features of BSS are discussed. The main principles of wavelet packet transform (WPT), principal component analysis (PCA) and support vector machine (SVM) have been reviewed. WPT is applied to the structural response signals, and feature vectors are obtained by feature extraction and PCA. The feature vectors are used for training and classification as the inputs of the support vector machine. The method is used to a single one-way arched beam string structure for damage detection. The cable prestress loss and web members damage experiment for a beam string structure is carried through. Different prestressing forces are applied on the cable to simulate cable prestress loss, the prestressing forces are calculated by the frequencies which are solved by Fourier transform or wavelet transform under impulse excitation. Test results verify this method is accurate and convenient. The damage cases of web members on the beam are tested to validate the efficiency of the method presented in this study. Wavelet packet decomposition is applied to the structural response signals under ambient vibration, feature vectors are obtained by feature extraction method. The feature vectors are used for training and classification as the inputs of the support vector machine. The structural damage position and degree can be identified and classified, and the test result is highly accurate especially combined with principle component analysis.

Random Imperfection Method for Stability Analysis of a Suspended Dome

Xuechun Liu,Xinxin Zhan,Ailin Zhang,Xun Zh,Chen Tian 한국강구조학회 2017 International Journal of Steel Structures Vol.17 No.1

The traditional eigenvalue buckling mode method used for the stability analysis of suspended domes has been deemed unsafe and unreasonable. A random imperfection method is proposed in this paper that is suitable for the stability analysis of suspended domes. Using this method, the impact of initial imperfections, such as joint position deviation, eccentricity of members, variation in cable pretension and elastic modulus of materials, on the stability of nonlinear geometries as well as the stability of both nonlinear geometries and materials (i.e., ultimate bearing capacity) are studied. The analysis results using this method are compared to those obtained from the traditional eigenvalue buckling mode method. This study indicates that the random imperfection method can more reasonably demonstrate the impact of initial imperfections on the stability of suspended domes. Additionally, the shape and size of the initial imperfections applied by the random imperfection method are more reasonable, and the results are safer. The random imperfection method is successfully used in the stability analysis of a largespan suspended dome, and the results of this method are nearly equivalent to that of the model test, which verifies the method.

Abnormalities in Inflammatory Cytokines Confer Susceptible to Chronic Neuropathic Pain-related Anhedonia in a Rat Model of Spared Nerve Injury

Xi Fang,Gaofeng Zhan,Jie Zhang,Hui Xu,Bin Zhu,Yimin Hu,Chun Yang,Ailin Luo 대한정신약물학회 2019 CLINICAL PSYCHOPHARMACOLOGY AND NEUROSCIENCE Vol.17 No.2

Objective: Patients with chronic neuropathic pain (CNP) have a higher incidence to develop depression. However, its pathogenesis has not yet been fully elucidated. Here we aimed to investigate the role of inflammatory cytokines in CNP-related anhedonia, which is a core symptom of depression, and to explore the effects of ketamine and parecoxib on pain and anhedonia. Methods: A rat model of spared nerve injury (SNI) was constructed to mimic CNP. Hierarchical cluster analysis of sucrose preference test (SPT) was applied to classify the SNI rats into anhedonia susceptible and unsusceptible. Inflammatory cytokines in medial prefrontal cortex (mPFC) of brain, serum and L2-5 spinal cord were measured. Moreover, effects of ketamine or parecoxib on mechanical withdrawal test (MWT) and SPT in anhedonia susceptible rats were detected. Results: Tumor necrosis factor (TNF)- was increased in mPFC, serum and and spinal cord of anhedonia susceptible rats. Furthermore, anhedonia susceptible and unsusceptible rats both increased the interleukin (IL)-1 level in mPFC, serum and spinal cord. IL-6 was altered in serum and spinal cord, but not in mPFC. IL-10 was significantly altered in mPFC and serum, but not in spinal cord. Additionally, ketamine treatment significantly attenuated the decreased results of MWT and SPT in anhedonia susceptible rats, and that parecoxib significantly improved the MWT score, but failed to alter the result of SPT. Conclusion: These findings suggest that abnormalities in inflammatory cytokines confer susceptible to anhedonia in a rat model of SNI. Ketamine, a fast-acting antidepressant, has pharmacological benefits to alleviate pain and anhedonia symptoms.