Experimental Study on the Effect of Boundary Layer on High-Speed Train Aerodynamic Forces Measurement

Zhixiang Huang,Weiping Zeng,Jie Gai,Hanjie Huang 대한토목학회 2021 KSCE JOURNAL OF CIVIL ENGINEERING Vol.25 No.5

The influences of boundary layer thickness on the aerodynamic characteristics of a high-speed train head car were investigated with an 1:8 scaled model in an 8 m × 6 m wind tunnel at CARDC. Boundary layer thicknesses at different positions on the ballast surface were measured under the wind velocity range of 40 to 70 m/s and the Reynolds number range of 1.25 × 106 to 2.19 × 106. It was found that the effect of Reynolds number on the head car was small. The boundary layer thickness increased significantly along the ballast and decreased gradually with the increase of the wind velocity. A linearly fitted model was employed to calculate the boundary layer thickness under different wind velocities. The changing patterns of the drag and lift force coefficients with the boundary layer thickness were complex. The drag and lift coefficients increased by 5.57% and 21.97% respectively, when the boundary layer thickness was larger than 118 mm. The effects of boundary layer on lift coefficients were more prominent than on the drag coefficients.

Experimental study on the influence of Reynolds number and roll angle on train aerodynamics

Zhixiang Huang,Wenhui Li,Tanghong Liu,Li Chen 한국풍공학회 2022 Wind and Structures, An International Journal (WAS Vol.35 No.2

When the rolling stocks run on the curve, the external rail has to be lifted to a certain level to balance the centrifugal force acting on the train body. Under such a situation, passengers may feel uncomfortable, and the slanted vehicle has the potential overturning risks at high speed. This paper conducted a wind tunnel test in an annular wind tunnel with φ=3.2 m based on a 1/20th scaled high-speed train (HST) model. The sensitivity of Reynolds effects ranging from Re = 0.37×106 to Re = 1.45×106 was tested based on the incoming wind from U=30 m/s to U=113 m/s. The wind speed covers the range from incompressible to compressible. The impact of roll angle ranging from γ=0° to γ=4° on train aerodynamics was tested. In addition, the boundary layer development was also analyzed under different wind speeds. The results indicate that drag and lift aerodynamic coefficients gradually stabilized and converged over U=70 m/s, which could be regeared as the self-similarity region. Similarly, the thickness of the boundary layer on the floor gradually decreased with the wind speed increase, and little changed over U=80 m/s. The rolling moment of the head and tail cars increased with the roll angle from γ=0° to γ=4°. However, the potential overturning risks of the head car are higher than the tail car with the increase of the roll angle. This study is significant in providing a reference for the overturning assessment of HST.

Effects of cyclic loads on viscoelastic behavior of brain tissue on the implanting trajectory of STN-DBS

Zhixiang Huang,Chunyang Pan,Panling Huang,Jun Zhou,Xueen Li 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.4

During deep brain stimulation of the sub-thalamic nucleus (STN-DBS), frequently adjusting the position of the cannula may lead to changes in tissue viscoelasticity. To investigate the mechanical properties of tissue on implant path at repeated loads, three cyclic tension and relaxation tests were carried out at 10 % and 20 % strains. Results indicated that white matter was about 25 %-140 % stiffer than gray matter. Within 20 % strain, the natural viscoelasticity of tissue was not affected by the repeated tension. Whereas at 20 % strain, irreversible internal structure rearrangements occurred at the first relaxation due to the persistent strain action, and almost 60 % of the attenuation modulus generated in the initial 5 s of the process, which leads to a softer transformation of the tissue. Further simulated puncture experiments revealed that an irreversible depression occurred when the cerebral hemisphere was subjected to a constant pressure of cannula for 5 s.

Experimental study on fabrication of large-scale micro cylinders array by mask jet electrochemical deposition

Ting Huang,Zhongning Guo,Guiming Liang,Shunzhi Qiao,Pengcheng Cai,Zhixiang Zou 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.8

The mask jet electrochemical deposition was used to deposit the large-scale micro cylinders array in this study. The effect of the pulse peak current density, pulse frequency, pulse duty cycle, injection pressure and scanning speed on the deposition characteristics (i.e. deposition height, surface roughness and surface quality of micro cylinders) have been investigated. The experiment results showed that the mean height and the surface roughness of micro cylinders increased form the peak current density. Moreover, due to a high pulse frequency provided a shorter pulse on-time, and significantly facilitating the renewal of the ion concentration in the electroforming fluid. A higher pulse frequency and larger duty cycle provide a better deposition characteristic. The injection pressure was found to have a significant effect on the height, the surface roughness and surface appearance of micro cylinders. Furthermore, when using higher scanning speed, the crystalline particles of the cast layer decrease, significantly decreasing the surface roughness. Based on discussed, the pulse current density of 12 A/dm 2 , a pulse frequency of 3000 Hz, a pulse duty cycle of 30 %, a jet inlet pressure of 80 kPa, a scanning speed of 8 mm/s and a number of scans of 100 is optimal parameters. Finally, by using these parameters, a large-area micro cylindrical array structures with a height of 22.53±2.46 μm and diameter of 205±3.21 μm were successfully fabricated. It can be concluded that the mask jet electrochemical deposition is a simple method to realize the electrodeposition of large-area array structures.

Variation in limonin and nomilin content in citrus fruits of eight varieties determined by modified HPLC

Shengjia Huang,Xinya Liu,Bo Xiong,Xia Qiu,Guochao Sun,Xiaojia Wang,Xu Zhang,Zhixiang Dong,Zhihui Wang 한국식품과학회 2019 Food Science and Biotechnology Vol.28 No.3

The nomilin and limonin content in citrus fruitsof different varieties was determined at fruit growth andmaturation stages by HPLC. The results showed that thetwo limonoids can be separated, identified, and quantifiedin citrus fruits within 10 min by the developed method. Themethod exhibited good precision, repeatability, stability,and recovery rate. The content of limonin and nomilin inmost citrus fruits presented an increasing trend initially,and then decreased during fruit growth and maturation; apeak was observed at the young fruit or fruit expansionstage. The dropped fruits also contained some amount oflimonoids, suggesting their industrial application. Thevariation and cluster analyses results revealed that theorange varieties contained the highest amount of limonoidsat the mature stage. The results of this study will enablebetter use of citrus limonoids.

pH/Temperature Responsive Curcumin-Loaded Micelle Nanoparticles Promote Functional Repair after Spinal Cord Injury in Rats via Modulation of Inflammation

Qian Taibao,Li Zhixiang,Shang Lijun,Huang Sutao,Li Guanglin,Zheng Weiwei,Mao Yingji 한국조직공학과 재생의학회 2023 조직공학과 재생의학 Vol.20 No.6

BACKGROUND: The formation of an inhibitory inflammatory microenvironment after spinal cord injury (SCI) remains a great challenge for nerve regeneration. The poor local microenvironment exacerbates nerve cell death; therefore, the reconstruction of a favorable microenvironment through small-molecule drugs is a promising strategy for promoting nerve regeneration. METHODS: In the present study, we synthesized curcumin-loaded micelle nanoparticles (Cur-NPs) to increase curcumin bioavailability and analyzed the physical and chemical properties of Cur-NPs by characterization experiments. We established an in vivo SCI model in rats and examined the ability of hind limb motor recovery using Basso–Beattie– Bresnahan scoring and hind limb trajectory assays. We also analyzed neural regeneration after SCI using immunofluorescence staining. RESULTS: The nanoparticles achieved the intelligent responsive release of curcumin while improving curcumin bioavailability. Most importantly, the released curcumin attenuated local inflammation by modulating the polarization of macrophages from an M1 pro-inflammatory phenotype to an M2 anti-inflammatory phenotype. M2-type macrophages can promote cell differentiation, proliferation, matrix secretion, and reorganization by secreting or expressing pro-repair cytokines to reduce the inflammatory response. The enhanced inflammatory microenvironment supported neuronal regeneration, nerve remyelination, and reduced scar formation. These effects facilitated functional repair in rats, mainly in the form of improved hindlimb movements. CONCLUSION: Here, we synthesized pH/temperature dual-sensitive Cur-NPs. While improving the bioavailability of the drug, they were also able to achieve a smart responsive release in the inflammatory microenvironment that develops after SCI. The Cur-NPs promoted the regeneration and functional recovery of nerves after SCI through anti-inflammatory effects, providing a promising strategy for the repair of SCIs.

Modification of disused floral foam with polyethylene diamine for the removal of heavy metal ions

Yilin Yu,Jindeng Huang,Yingmin Liao,Zhixiang Lin,Xiaojia Huang 한국공업화학회 2023 Journal of Industrial and Engineering Chemistry Vol.128 No.-

Floral foam (FF) based on phenol formaldehyde resin has been used widely for many years, but it is reusedrarely and the discarded FF is harmful to environment. Therefore, recycling of disused FF is interestingand highly required. In current study, a new strategy for reutilization of disused FF was proposed. FFwhich had been treated with NaOH solution was dipped in polyethyleneimine (PEI) solution to anchoractive amino groups on the framework of FF, and then glutaraldehyde was employed to cross-link theanchored PEI to obtain a novel adsorbent based on disused FF (PEI@FF). Due to the abundant aminogroups, the prepared adsorbent displayed satisfactory chelating ability towards heavy metal ions. Under the optimal synthesis and adsorption conditions, the PEI@FF was applied to remove Cu(II), Cd(II) and Pb(II) in environmental waters, and the removal rates varied from 91.4% to 95.6%, which weremuch higher than that achieved on unmodified FF (35–43%). Additionally, the PEI@FF exhibited goodbatch-to-batch preparation repeatability and acceptable number of cyclic utilization. The satisfactoryresults well evidence the proposed method is practicable for reutilization of discarded FF, and the presentstudy also supplies a new adsorbent for the high efficient removal of heavy metal ions.

Modal parameter identification of civil structures using symplectic geometry mode decomposition

Feng Hu,Lun-hai Zhi,Zhixiang Huang,Bo Chen 한국풍공학회 2023 Wind and Structures, An International Journal (WAS Vol.36 No.1

In this article, a novel structural modal parameters identification methodology is developed to determine the natural frequencies and damping ratios of civil structures based on the symplectic geometry mode decomposition (SGMD) approach. The SGMD approach is a new decomposition algorithm that can decompose the complex response signals with better decomposition performance and robustness. The novel method firstly decomposes the measured structural vibration response signals into individual mode components using the SGMD approach. The natural excitation technique (NExT) method is then used to obtain the free vibration response of each individual mode component. Finally, modal natural frequencies and damping ratios are identified using the direct interpolating (DI) method and a curve fitting function. The effectiveness of the proposed method is demonstrated based on numerical simulation and field measurement. The structural modal parameters are identified utilizing the simulated non-stationary responses of a frame structure and the field measured non-stationary responses of a supertall building during a typhoon. The results demonstrate that the developed method can identify the natural frequencies and damping ratios of civil structures efficiently and accurately.

Nuclide Guide and International Chart of the Nuclides - 2009

Tengiz Golashvili,Sergey Badikov,Zhao Zhixiang,Huang Xiaolong,Ge Zhigang,Wu Zhendong,Valery Chechev 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.59 No.23

New versions of Nuclide Guide (NG) and Chart of the Nuclides (CN) were developed as a result of Russian-Chinese collaboration. Compared to the previous versions of the NG and CN - 2006 new evaluated information has been included to the NG and CN - 2009 from the following publications: 1) Nuclear Data Sheets, volumes 107 - 110, 2) Monographie BIPM-5, Table of Radionuclides, 2006, 3) Monographie BIPM-5, Table of Radionuclides, 2008. In addition, for the Nuclide Guide-2009 the authors re-calculated the average energies of radiations of the 500 radionuclides with half-lives about and more than 1 hour. The International Chart of Nuclides was developed taking into account information added and revised in Nuclide Guide-2009. The presented decay data can be used not only in nuclear physics and associated fields but also in medicine, agriculture and space studies.

Effect of silicone rubber-sleeve mounted on shear studs on shear stiffness of steel-concrete composite structures

Chang Yang,Decan Yang,Caiping Huang,Zhixiang Huang,Lizhi Ouyang,Landon Onyebueke,Lin Li 국제구조공학회 2022 Steel and Composite Structures, An International J Vol.44 No.5

Earlier works have shown that excessive shear stiffness at the steel-concrete interface causes a non-uniform distribution of shear force in composite structures. When the shear studs are wrapped at the fixed end with flexible materials with a low elastic modulus, the shear stiffness at the interface is reduced. The objective of this study was to investigate the effect of silicone rubber-sleeve mounted on shear studs on the shear stiffness of steel-concrete composite structures. Eighteen push-out tests were conducted to investigate the mechanical behavior of silicone rubber-sleeved shear stud groups (SRS-SSG). The dimension and arrangement of silicon rubber-sleeves (SRS) were taken into consideration. Test results showed that the shear strength of SRS-SSG was higher than that of a shear stud group (SSG), without SRS. For SRS-SSG with SRS heights of 50 mm, 100 mm, 150 mm, the shear strengths were improved by 13%, 20% and 9%, respectively, compared to the SSG alone. The shear strengths of SRS-SSG with the SRS thickness of 2 mm and 4 mm were almost the same. The shear stiffness of the SRS-SSG specimens with SRS heights of 50 mm, 100 mm and 150 mm were 77%, 67% and 66% of the SSG specimens, respectively. Test results of specimens SSG-1 and predicted values based on the three design specifications were compared. The nominal single stud shear strength of SSG-1 specimens was closest to that calculated by the Chinese Code for Design of Steel Structures (GB50017-2017). An equation is proposed to consider the effects of SRS for GB50017-2017, and the predicted values based on the proposed equation agree well with the tested results of SRS-SSG.