http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
The effect of bending loads on the dynamic behaviors of a rolling guide
James Shih-Shyn Wu,Jyh-Cheng Chan,Gent-An Tsai,Ching-Yuan Lin,Feng-Ming Ou 대한기계학회 2012 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.26 No.3
Dynamic behaviors of ball-type contact surfaces under unbalanced bending loads are studied using point-to-point analysis, threedimensional finite element simulation based on the Hertz Contact Theory, and a modal test. Results derived from these models are very similar but the Finite Element Model provides the best results since it allows for more elements of study, such as the steel ball, carriage,rail etc. In the study, results also show that frequencies vary slightly, but there is an obvious change in shapes. Therefore, the contact stiffness in simulations must be properly selected with the conclusion that different external loadings may affect the dynamic characteristics of such structures significantly.
3D contact analysis of conjugate spur gears by a complete mating process
James Shih-Shyn Wu,Shu-Ling Xu,Yi-Tsung Lin,Wei-Hung Chen,Yuan-Lung Lai 대한기계학회 2013 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.27 No.12
Instead of applying fixed boundary conditions to constrain and simplify material behavior in 2D models, the point and line contact of tooth surfaces are substituted by a face-contact model of teeth in this study. The inaccurate prediction of load, deformation, and stress in 3D contacts are solved. Most research uses one pair to three pairs of meshing teeth to simulate the mating process. However, describing the entire process of three contact zones during each mating pair is insufficient. By implementing a combined 3D face contact and finite element method, the contact stress analyses between two spur gear teeth are conducted in 11 different contact positions during a full mating process. The proposed approach provides a complete and effective solution to the contact problem in a quasi-dynamic manner. This model not only determines the load-sharing prediction but also verifies the applied boundary conditions.
Changqing Wu,Feng Chen,James W. Rushing,Xi Wang,김현진,George Huang,Vivian Haley-Zitlin,Guoqing He 한국식품영양과학회 2006 Journal of medicinal food Vol.9 No.1
The medicinal herb feverfew [Tanacetum parthenium (L.) Schultz-Bip.] has long been used as a folk remedyfor the treatment of migraine and arthritis. Parthenolide, a sesquiterpene lactone, is considered to be the primary bioactivecompound in feverfew having anti-migraine, anti-tumor, and anti-inflammatory properties. In this study we determined, throughin vitrobioassays, the inhibitory activity of parthenolide and golden feverfew extract against two human breast cancer celllines (Hs605T and MCF-7) and one human cervical cancer cell line (SiHa). Feverfew ethanolic extract inhibited the growthof all three types of cancer cells with a half-effective concentration (EC50) of 1.5 mg/mL against Hs605T, 2.1 mg/mL againstMCF-7, and 0.6 mg/mL against SiHa. Among the tested constituents of feverfew (i.e., parthenolide, camphor, luteolin, andapigenin), parthenolide showed the highest inhibitory effect with an EC50 against Hs605T, MCF-7, and SiHa of 2.6 .g/mL,2.8 .g/mL, and 2.7 .g/mL, respectively. Interactions between parthenolide and flavonoids (apigenin and luteolin) in fever-few extract also were investigated to elucidate possible synergistic or antagonistic effects. The results revealed that apigeninand luteolin might have moderate to weak synergistic effects with parthenolide on the inhibition of cancer cell growth ofHs605T, MCF-7, and SiHa.
Assessment of the Counter-Flow Thrust Vector Control in a Three-Dimensional Rectangular Nozzle
Kexin Wu,Tae Ho Kim(김태호),James Jintu Kochupulickal,Heuy Dong Kim(김희동) 한국추진공학회 2020 한국추진공학회지 Vol.24 No.1
Computational assessment of gas-dynamic characteristics is explored for a three-dimensional counter-flow thrust vector control system in a rectangular supersonic nozzle. This convergent-divergent nozzle is designed by Method of Characteristics and its design Mach number is specially set as 2.5. Performance variations of the counter-flow vector system are illustrated by varying the gap height of the secondary flow duct. Key parameters are quantitatively analyzed, such as static pressure distribution along the centerline of the upper suction collar, deflection angle, secondary mass flow ratio, and resultant thrust coefficient. Additionally, the streamline on the symmetry plane, three-dimensional iso-Mach number surface contour, and three-dimensional turbulent kinetic energy contour are presented to reveal overall flow-field characteristics in detail.
Heo, Jongbae,Wu, Bo,Abdeen, Ziad,Qasrawi, Radwan,Sarnat, Jeremy A.,Sharf, Geula,Shpund, Kobby,Schauer, James J. Elsevier 2017 Environmental pollution Vol.225 No.-
<P><B>Abstract</B></P> <P>This manuscript evaluates spatial and temporal variations of source contributions to ambient fine particulate matter (PM<SUB>2.5</SUB>) in Israeli, Jordanian, and Palestinian cities. Twenty-four hour integrated PM<SUB>2.5</SUB> samples were collected every six days over a 1-year period (January to December 2007) in four cities in Israel (West Jerusalem, Eilat, Tel Aviv, and Haifa), four cities in Jordan (Amman, Aqaba, Rahma, and Zarka), and three cities in Palestine (Nablus, East Jerusalem, and Hebron). The PM<SUB>2.5</SUB> samples were analyzed for major chemical components, including organic carbon and elemental carbon, ions, and metals, and the results were used in a positive matrix factorization (PMF) model to estimate source contributions to PM<SUB>2.5</SUB> mass. Nine sources, including secondary sulfate, secondary nitrate, mobile, industrial lead sources, dust, construction dust, biomass burning, fuel oil combustion and sea salt, were identified across the sampling sites. Secondary sulfate was the dominant source, contributing 35% of the total PM<SUB>2.5</SUB> mass, and it showed relatively homogeneous temporal trends of daily source contribution in the study area. Mobile sources were found to be the second greatest contributor to PM<SUB>2.5</SUB> mass in the large metropolitan cities, such as Tel Aviv, Hebron, and West and East Jerusalem. Other sources (i.e. industrial lead sources, construction dust, and fuel oil combustion) were closely related to local emissions within individual cities. This study demonstrates how international cooperation can facilitate air pollution studies that address regional air pollution issues and the incremental differences across cities in a common airshed. It also provides a model to study air pollution in regions with limited air quality monitoring capacity that have persistent and emerging air quality problems, such as Africa, South Asia and Central America.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Secondary Sulfate is the dominant source of PM<SUB>2.5</SUB> in the Middle East. </LI> <LI> Secondary inorganic aerosols show relatively homogeneous temporal trends. </LI> <LI> Other sources are largely related to local emissions within individual cities. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Characterization of the dynamic behavior of a linear guideway mechanism
Chang, Jyh-Cheng,Wu, Shih-Shyn James,Hung, Jui-Pin Techno-Press 2007 Structural Engineering and Mechanics, An Int'l Jou Vol.25 No.1
Dynamic behaviors of the contact surface between ball and raceway in a guideway mechanism vary with the applied loads and hence affect the mechanical responses of machine tools. The study aims to investigate the nonlinear characteristics of dynamic behaviors at the rolling contact interface in linear guideway mechanisms. Firstly, analytical method was introduced to understand the contact behaviors based on Hertz contact theory in a point-to-point way. Then, the finite element approach with a three-dimensional surface-to-surface contact model and appropriate contact stiffness was developed to study the dynamic characteristics of such linear guideways. Finally, experiments with modal test were conducted to verify the significance of both the analytical and the numerical results. Results told that the finite element approach may provide significant predictions. The study results also concluded that the current nonlinear models based on Hertz's contact theory may accurately describe the contact characteristic of a linear guideway mechanism. In the modal analysis, it was told that the natural frequencies vary a little with different loading conditions; however, the mode shapes are changed obviously with the magnitude of applied loads. Therefore, the stiffness of contact interface needs to be properly adjusted during simulation which may affect the dynamic characteristics of the machine tools.