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Room-temperature tensile strength and thermal shock behavior of spark plasma sintered W-K-TiC alloys
Ke Shi,Bo Huang,Bo He,Ye Xiao,Xiaoliang Yang,Youyun Lian,Xiang Liu,Jun Tang 한국원자력학회 2019 Nuclear Engineering and Technology Vol.51 No.1
W-K-TiC alloys with different titanium carbide concentrations (0.05, 0.1, 0.25, 0.5, 1, 2) wt.% werefabricated through Mechanical Alloying and Spark Plasma Sintering. The effects of the addition of nanoscaledTiC particles on the relative density, Vickers micro-hardness, microstructure, crystal information,thermal shock resistance, and tensile strength were investigated. It is revealed that the doped TiC nanoparticleslocated at the grain boundaries. The relative density and Vickers micro-hardness of W-K-TiCalloys was enhanced with TiC addition and the highest Vickers micro-hardness is 731.55. As the TiCaddition increased from 0.05 to 2 wt%, the room-temperature tensile strength raised from 141 to353 MPa. The grain size of the W-K-TiC alloys decreased sharply from 2.56 mm to 330 nm with theenhanced TiC doping. The resistance to thermal shock damage of W-K-TiC alloys was improved slightlywith the increased TiC addition
Orthogonal Analysis and Optimization of a K4-Rating Auto-Lifting Anti-Ram Bollard System
Ke Cao,Guo-Qiang Li,Suwen Chen,Yu Zhang,Bo Hu 한국강구조학회 2016 International Journal of Steel Structures Vol.16 No.2
The anti-ram bollard system (ABS) is installed around the perimeter of buildings and infrastructures to prevent the penetration of unauthorized vehicles and reduce the blast and debris caused by the vehicle-borne improvised explosive devices (VBIED). Comparing with the fixed anti-ram bollard system (FABS), the auto-lifting anti-ram bollard system (AABS) has the advantage to be set down automatically to allow authorized vehicles passing on. In this paper, a configuration of K4-rating AABS is proposed and a finite-element model is developed to simulate its performance. Differences between vehicle model and real vehicle, effects of boundary conditions are both taken into account. The effectiveness and accuracy of the numerical simulation are validated through predicting the results of relevant experiments. Based on the verified numerical model, 32 groups of numerical experiments of K4-rating AABS are investigated using an orthogonal array L32 (48 ×81). The order and significant levels of nine affecting factors are identified on the basis of the range analysis and variance analysis, respectively. It shows that gaps between substructure and outer sleeve, wall thickness of substructure, wall thickness of steel tube, diameter of steel tube and thickness of stiffening ribs have significant influences on the behavior of AABS. The optimal design is proposed according to the orthogonal analysis.
Energy Management of a Grid-connected High Power Energy Recovery Battery Testing System
Ke Zhang,Bo Long,Cheol-Jung Yoo,Hye-Min Noh,Young-Won Chang 대한전기학회 2016 Journal of Electrical Engineering & Technology Vol.11 No.4
Energy recovery battery testing systems (ERBTS) have been widely used in battery manufactures. All the ERBTS are connected in parallel which forms a special and complicated microgrid system, which has the shortcomings of low energy recovery efficiency, complex grid-connected control algorithms issues for islanded detection, and complicated power circuit topology issues. To solve those shortcomings, a DC micro-grid system is proposed, the released testing energy has the priority to be reutilized between various testing system within the local grid, Compared to conventional scheme, the proposed system has the merits of a simplified power circuit topology, no needs for synchronous control, and much higher testing efficiency. The testing energy can be cycleused inside the local micro-grid. The additional energy can be recovered to AC-grid. Numerous experimental comparison results between conventional and proposed scheme are provided to demonstrate the validity and effectiveness of the proposed technique.
Ke Ren,Wentao Duan,Yujun Shi,Bo Li,Zuojin Liu,Jiangping Gong 대한의학회 2010 Journal of Korean medical science Vol.25 No.7
In order to prove that ectopic over-expression of Pim-2 could induce malignant transformation of human liver cell line L02, three groups of cells were set up including human liver cell line L02 (L02), L02 cells transfected with Pim-2 gene (L02/Pim-2) and L02cells transfected with empty-vector (L02/Vector). Pim-2 expression levels were detected. The morphology, proliferation level, apoptosis rate and migration ability of the cells were detected respectively. Then the cells were subcutaneously inoculated into athymic mice and the microstructures of the neoplasm were observed. Compared with the controls, Pim-2expression levels were significantly higher in L02/Pim-2 cells (P<0.05), and their morphology had obvious malignant changes. They also showed a significantly increased proliferation rate (P<0.05) and migration capacity (P<0.05), as well as a significantly decreased apoptosis rate (P<0.05). Only the athymic mice inoculated with L02/Pim-2 cells could generate neoplasm, and the morphology of the neoplasm coincided with that of the hepatoma. The results manifest that ectopic Pim-2 gene could be stably expressed in L02/Pim-2 cells. Both the morphological and biological changes of L02/Pim-2 cells demonstrate the trend of malignant transformation. L02/Pim-2 cells could generate hepatoma in athymic mice. In conclusion, Pim-2 could induce malignant transformation of human liver cell line L02.
Ke-Ming Wang,Feng Chen,Hui Hu,Hui-Hao Xia,Xue-Lin Wang,Bo-Rong Shi,Qing-Ming Lu 한국진공학회(ASCT) 2003 Applied Science and Convergence Technology Vol.12 No.S1
Both LiNbO₃ and KTiOPO₄ samples were implanted with 350 keV H^+ and He^+ ions at different doses ranging from 1×10^(16) to of 5×10^(16) ions/㎠. Single and multi-energy implantations were performed at room temperature. Mono-mode or a few modes in both LiNbO₃ and KTiOPO₄ waveguides were observed. The effect of temperature on the refractive index profiles of LiNbO₃ and KTiOPO₄ waveguids was studied. The temperature covered from room temperature, 200℃, 194.5 K (dry ice) and 77K (liquid nitrogen). Different mechanisms are needed to interpret the observed behavior. A n_e increased mono-mode LiNbO₃ waveguide was formed by multi-energy keV He^+ ions.
Full-scale measurements of wind effects and modal parameter identification of Yingxian wooden tower
Bo Chen,Qingshan Yang,Ke Wang,Linan Wang 한국풍공학회 2013 Wind and Structures, An International Journal (WAS Vol.17 No.6
The Yingxian wooden tower in China is currently the tallest wooden tower in the world. It was built in 1056 AD and is 65.86 m high. Field measurements of wind speed and wind-induced response of this tower are conducted. The wind characteristics, including the average wind speed, wind direction, turbulence intensity, gust factor, turbulence integral length scale and velocity spectrum are investigated. The power spectral density and the root-mean-square wind-induced acceleration are analyzed. The structural modal parameters of this tower are identified with two different methods, including the Empirical Mode Decomposition (EMD) combined with the Random Decrement Technique (RDT) and Hilbert transform technique, and the stochastic subspace identification (SSI) method. Results show that strong wind is coming predominantly from the West-South of the tower which is in the same direction as the inclination of the structure. The Von Karman spectrum can describe the spectrum of wind speed well. Wind-induced torsional vibration obviously occurs in this tower. The natural frequencies identified by EMD, RDT and Hilbert Transform are close to those identified by SSI method , but there is obvious difference between the identified damping ratios for the first two modes.
Bo Zhang,Yong Yang,Yuan-feng Wei,Ru-yue Liu,Chu Ding,Ke-qiang Zhang 국제구조공학회 2015 Structural Engineering and Mechanics, An Int'l Jou Vol.55 No.6
In this study, a new retrofitting method for improving the seismic performance of reinforced concrete column was presented, in which prestressed steel strips were utilized as retrofitting stuff to confine the reinforced concrete column transversely. In order to figure out the seismic performance of concrete column specimen retrofitted by such prestressed steel strips methods, a series of quasi-static tests of five retrofitted specimens and two unconfined column specimen which acted as control specimens were conducted. Based on the test results, the seismic performance including the failure modes, hysteresis performance, ductility performance, energy dissipation and stiffness degradation of all these specimens were fully investigated and analyzed. And furthermore the influences of some key parameters such as the axial force ratios, shear span ratios and steel strips spacing on seismic performance of those retrofitted reinforced concrete column specimens were also studied. It was shown that the prestressed steel strips provided large transverse confining effect on reinforced concrete column specimens, which resulted in improving the shearing bearing capacity, ductility performance, deformation capacity and energy dissipation performance of retrofitted specimens effectively. In comparison to the specimen which was retrofitted by the carbon fiber reinforced plastics (CFRP) strips method, the seismic performance of the specimens retrofitted by the prestressed steel strips was a bit better, and with much less cost both in material and labor. From this research results, it can be concluded that this new retrofitting method is really useful and has significant advantages both in saving money and time over some other retrofitting methods.