Monitoring Sluice Health in Vibration by Monocular Digital Photography and a Measurement Robot

Guojian Zhang,Chengxin Yu,Guangli Guo,Long Li,Yongqian Zhao,Huaizhan Li,Yaqiang Gong 대한토목학회 2019 KSCE JOURNAL OF CIVIL ENGINEERING Vol.23 No.6

This study uses monocular digital photography and a measurement robot (MDP&MR) to monitor the sluice vibration deformation in the gate lift test and in the sluicing test. The photographing scale transformation and time baseline parallax (PST-TBP) method is proposed in the field of monocular digital photography. Results show that the PST-TBP method improves measurement accuracy slightly. Measurement accuracies on the reference plane were 0.62 pixels (0.40 mm), 0.76 pixels (0.49 mm), and 1.10 pixels (0.71 mm) in the X, Z, and comprehensive-directions, respectively. The PST-TBP method overcomes the limitation that the photographing direction must be perpendicular to the sluice plane when monocular digital photography is used to monitor the sluice. MDP&MR proves an effective method in monitoring the sluice vibration deformation as MDP can be used to monitor the trend of the sluice vibration deformation and the MR allows high-accuracy monitoring of the short periodic deformation of the sluice. They have complementary advantages to achieve better results. Thus, MDP&MR can provide a new way to assess sluice health in vibration.

Failure Mechanism of Giant-Thick Strata Characterized by Weak Cementation Based on Superimposed Similar Material Simulation

Guojian Zhang,Guangli Guo,Yaqiang Gong,Anliang Xiao,Tonglong Zhao,Huaizhan Li 대한토목학회 2022 KSCE JOURNAL OF CIVIL ENGINEERING Vol.26 No.8

Deep mining puts forward higher requirements for the existing similar material simulation methods and monitoring techniques. The idea of superimposed similar material simulation is proposed to study the motion mechanism of high-stand and giant-thickness weak cementation sandstone, and its motion law is observed by the new method of single-binocular close-range photogrammetry, and verified by numerical simulation method. The results show that: first, the measurement accuracy of single close-range photogrammetry reaches the sub-millimeter level, with its medium errors of 0.18 mm and 0.17 mm in left and right camera respectively. Second, during the damage process of the thick weak cementation strata, the secondary equilibrium structure and regenerative equilibrium structure are formed, causing the destruction mode to go through four stages of ‘arch shell-beam-arch shell-step’ type damage. After the ‘arch shell-beam’ type destruction of the thick Zhidan group sandstone, its movement process disappears in the temporal correlation and shows the characteristics of the surface subsiding immediately after mining. Last, the surface subsidence develops with the saltation, and there is a quadratic polynomial function between the surface subsidence coefficient and the width-depth ratio. The above results can be used to guide the safety mining under the giant-thick weak cementation overburden.

Study on the characteristics of zirconia ceramic in three-dimensional ultrasonic vibration-assisted ELID internal grinding

Fan Chen,Guojian Mei,Bo Zhao,Wenbo Bie,Guangxi Li 대한기계학회 2020 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.34 No.1

Three-dimensional (3D) ultrasonic vibration-assisted ELID grinding, which combines 3D ultrasonic vibration-assistance with electrolytic in-process grinding wheel dressing (ELID), is a compound process that is designed to achieve high-efficiency precision machining. A grinding force model of 3D ultrasonic vibration-assisted ELID grinding was first developed on the basis of the kinematics of a single grit particle and was verified through experimentation. The surface quality then was observed using white light interference profiling. It was demonstrated during the present investigation that the grinding force during 3D ultrasonic vibration-assisted ELID grinding was approximately 20 %~30 % lower than that of twodimensional (2D) ultrasonic vibration-assisted ELID grinding. In addition, the surface roughness (Ra) achieved during 3D ultrasonic vibration-assisted ELID grinding was approximately 40 %~50 % smoother than was achieved under 2D ultrasonic vibration-assisted ELID, and thus 3D ultrasonic vibration-assisted ELID grinding can achieve better surface quality.

Flexible Composites: Carbon Nanotube Fiber Based Stretchable Conductor (Adv. Funct. Mater. 7/2013)

Zu, Mei,Li, Qingwen,Wang, Guojian,Byun, Joon‐,Hyung,Chou, Tsu‐,Wei WILEY‐VCH Verlag 2013 Advanced Functional Materials Vol.23 No.7

<P>Stretchable conductors based on buckled carbon nanotube (CNT) fibers are fabricated using a simple prestraining‐then‐buckling approach. The primary deformation mode of the CNT fibers is lateral kinking. This buckling shape is quite different from the sinusoidal shape observed previously in systems that are otherwise similar. As reported by Tsu‐Wei Chou and co‐workers on page 789, the prepared CNT fiber/poly(dimethylsiloxane) (PDMS) composite film shows excellent stability and repeatability in performance as a stretchable conductor. </P>

Numerical simulation of holes and inclusions using adaptive polygonal finite element method

Shengyong Ding,Guojian Shao,Ang Li,Jingbo Su,Hougai Shi 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.9

An adaptive polygonal finite element method using the techniques of cut-cell and quadtree refinement is presented for modeling holes and inclusions in 2-D solids. A mesh template is used to ensure the high-quality refined elements generated in quadtree refinement. By coupling the level set method, the polygonal computational mesh is directly extracted from the mesh template in every adaptive cycle. An error estimator based on recovery stress is devoted for adaptive purpose, which allows the mesh where it is needed is further refining. This method allows to model arbitrary shape holes and inclusions in arbitrary-geometry 2-D solid using the initial mesh of few rectangular elements, which considerably simplifies construction of the finite element model. And one curved boundary can be accurately represented though several steps of refinement. Numerical examples are solved and the obtained results are compared with reference solutions to show the simplicity and efficiency of the proposed method.

Study on the thermoelectric properties of porous Bi-Te films deposited using thermal evaporation on AAO template

Shiying Liu,GUOJIAN LI,Mingdi Lan,Yongjun Piao,Yanan Zhang,QIANG WANG 한국물리학회 2020 Current Applied Physics Vol.20 No.3

The application of thermoelectric films is limited to retain the temperature gradient. In this study, the Bi-Te films are deposited on the AAO template with a pore size of 100 nm using thermal evaporation. The results show that the conductive types of the Bi-Te film are tuned by source temperature. The power factor of the p-type porous film decreases 36% by comparing to that of the p-type nonporous film (1020 μW/mK2 at 250 °C). Meanwhile, the temperature difference in the porous device is maintained and is approximately 5.0 °C. Thus, the maximum output power is achieved in the porous device (about 25 pW), which is 5 times higher than that of the nonporous device. This provides a method to improve the conversion efficiency of thermoelectric film device by maintaining the temperature difference by using porous structure.

EFFECTS OF HIGH MAGNETIC FIELD ON THE STRUCTURAL EVOLUTION AND MAGNETIC PROPERTIES OF NANOCRYSTALLINE Ni FILMS

JIAOJIAO DU,QIANG WANG,GUOJIAN LI,YONGZE CAO,JICHENG HE 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2014 NANO Vol.9 No.2

This paper studies the e®ects of a high magnetic feld on the structural evolution and magneticproperties of nanocrystalline Ni flms prepared on quartz substrates by a molecular beam vapordeposition (MBVD) method. Atomic force microscope, X-ray di®ractometer, transmission elecftron microscope and vibrating sample magnetometer were used to study the microstructures andmagnetic properties of the Ni flms. The results indicate that high magnetic feld has no obviousinfluence on crystal structures except changing the lattice constant of the Ni flms. However, thehigh magnetic feld can refne particle size. The flm deposited under magnetic feld tends to growthrough columnar mode because of the magnetized particles aligning along the direction ofmagnetic feld. Furthermore, the ordered and dense arrangement of Ni atoms results in more spinscontained in per unit volume and improves the saturation magnetization (Ms). Ms of the 6 T Ni¯lm increases by 70% (578 emu/cm3) than that of the ¯lm without magnetic ¯eld (341 emu/cm3),and the coercivity is also slightly increased for the 6 T flm.

Dynamics of fungal community during silage fermentation of elephant grass (Pennisetum purpureum) produced in northern Vietnam

Viet Ha Vu,Xiyang Li,Mengyuan Wang,Rongmei Liu,Guojian Zhang,Wei Liu,Baixue Xia,Qun Sun 아세아·태평양축산학회 2019 Animal Bioscience Vol.32 No.7

Objective: This study aimed to gain deeper insights into the dynamic changes in spoilage fungi populations during fermentation and the influence of traditional additives on silage quality. Methods: Elephant grass (Pennisetum purpureum) was prepared without any additive (control), and with the addition of 0.5% salt, and 0.5% salt–0.2% sugar mixture. The fungal community was then determined using a classic culturing method and high-throughput sequencing at 0, 5, 15, and 60 days after ensiling. Results: The results showed that the fungal community of elephant grass silage varied significantly between the natural fermentation without any additive and the two additive groups. The diversity and relative abundance of spoilage molds in the control group were much higher than those in the two treatment groups (p<0.05). Three species of yeasts (Candida sp., Pichia sp., Trichosporon sp.) and four spoilage molds (Fusarium sp., Aspergillus sp., Muco sp. and Penicillin sp.) were the predominant fungi in elephant grass during natural fermentation from 0 to 60 days, which were found to be significantly decreased in salt and sugar additive groups (p<0.05). Meanwhile, the diversity and relative abundance of undesirable molds in the 0.5%-salt additive group were the lowest among all groups. Conclusion: Adding salt and sugar, particularly 0.5% salt, is a promising effective approach to reduce the amount of undesirable fungi thus, improving the silage quality of elephant grass in northern Vietnam.

Scalded Skin of Rat Treated by Using Fibrin Glue Combined with Allogeneic Bone Marrow Mesenchymal Stem Cells

( Yadong Yang ),( Wenyuan Zhang ),( Ying Li ),( Guojian Fang ),( Keji Zhang ) 대한피부과학회 2014 Annals of Dermatology Vol.26 No.3

Background: It is difficult to achieve satisfactory results with the traditional treatment of large-area skin defects and deep burns. Objective: To test the treatment effect of an active dressing film made of a mixture of fibrin glue and bone marrow mesenchymal stem cells (BMSCs) for repairing burn wounds on the skin of rats. Methods: Two scald wounds were made on the back of each rat. A total of 30 scald wounds were randomly divided into 3 groups, with 10 wounds in each group. In the experimental treatment group, the scald wounds were covered with the fibrin glue and BMSC mixture. The wounds of the experimental control group were covered with fibrin glue only. No intervention was administered to the blank control group. Thirty days after treatment, pathological sections were cut from the scalded local tissues of all rats from the 3 groups and observed with a microscope. Results: The speed of scald wound healing in the experimental treatment group was faster than the other 2 groups. In the experimental treatment group, histopathological analysis revealed that the sebaceous glands showed obviously proliferous at the edge of the new tissue and gradually extended to the deep dermal layer of the new tissue. Conclusion: BMSCs may have an active role in promoting skin tissue repair and generating skin appendages. Allogeneic BMSCs mixed with fibrin glue can contribute to the quick formation of a film-like gel over the scald wounds, which might be of significance for emergency treatment and skin-grafting operations. (Ann Dermatol 26(3) 289∼295, 2014)

Experimental Study on the Seismic Mechanism of Full-scale Specimens of Superimposed Slab Shear Walls with Innovative Construction Details

Hongkang Zhao,Yaping Dai,Jun Yang,Youzhen Fang,Chengjie Mi,Lingchen Yang,Guojian Li 대한토목학회 2023 KSCE Journal of Civil Engineering Vol.27 No.6

The seismic performance of precast reinforced concrete structures has long been a source ofconcern that impedes their use in seismic regions and high-rise buildings. To further optimizethe reinforcement configuration and enhance the seismic performance of the superimposedslab shear wall structures, this research proposed a superimposed slab shear wall withinnovative construction details. Five innovative superimposed slab shear walls and one cast-inplaceconcrete shear wall were designed and tested under low cycle lateral load. The effect ofaxial compression was considered during tests and analyses as well. In this paper, the seismicperformance, including failure mode, hysteretic behavior, load-bearing capacity, lateralstiffness degradation, energy dissipation, and seismic ductility was investigated and analyzed. The experimental results showed that five innovative superimposed slab shear walls and onecast-in-place concrete shear wall exhibited a similar failure mode of flexural-shear failure, anda large area of concrete was damaged and crushed at the shear wall corner. However, the areaof crushing concrete in the cast-in-place concrete shear wall was relatively small. And the areaof crushing concrete in the superimposed slab shear walls increased with the axial compressionratio. For the superimposed slab shear walls, the development of concrete cracks decreasedgradually with the enlargement in the axial compression ratio, while the length of the cracksincreased in this respect. The results indicated that innovative superimposed slab shear wallshad a higher strength capacity and lower lateral-resistant stiffness than the cast-in-placeconcrete shear wall. With the enlargement in the axial compression ratio, the peak strengthcapacity of the superimposed slab shear wall increased obviously, while it degraded rapidlyafter the peak load. It is suggested that the contribution of axial compression to the shear resistcapacity of the inclined section should not be considered in practical design. Meanwhile, theductility coefficients of the six specimens were larger than 2.2, which was in accordance withthe seismic requirements. This investigation could provide effective experimental data forfuture structural seismic performance evaluations and applications of precast superimposedslab shear wall structures.