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1.
Rotating-bending uniaxial fatigue tests and micro-fatigue crack initiation tests were carried out using a permanent mold cast
(PMC) and semi-solid die cast (SDC) with Al−7%Si−0.35%Mg composition in order to examine the relationship between solidification
structures and fatigue behaviors. The crack length was measured using a replication method. Fatigue strength was improved
in SDC, which was almost consistent with the predicted fatigue strength using the size of Si particle cluster. Resistance
to fatigue crack initiation and fatigue strength were improved in SDC owing to the finer Si cluster and to higher ultimate
tensile strength. Fatigue crack in PMC was preferentially initiated at pores. For SDC, the fatigue crack was initiated at
the Si particle/matrix interface, and then sucessively grew along eutectic cell boundaries. 相似文献
2.
A simplified method for the computation of first-, second- and higher-order derivatives of eigenvalues and eigenvectors associated with repeated eigenvalues is presented. Adjacent eigenvectors and orthonormal conditions are used to compose an algebraic equation. The algebraic equation which is developed can be used to compute derivatives of eigenvalues and eigenvectors simultaneously. Since the coefficient matrix in the proposed algebraic equation is non-singular, symmetric and based on N-space, it is numerically stable and very efficient compared to previous methods. To verify the efficiency of the proposed method, the finite element model of the cantilever beam and a mechanical system in the case of a non-proportionally damped system are considered. 相似文献
3.
On social Web sites 总被引:1,自引:0,他引:1
Today hundreds of millions of Internet users are using thousands of social Web sites to stay connected with their friends, discover new “friends,” and to share user-created contents, such as photos, videos, social bookmarks, and blogs. There are so many social Web sites, and their features are evolving rapidly. There is controversy about the benefits of these sites, and there are social issues these sites have given rise to. There are lots of press articles, Wikipedia articles, and blogs—in varying degrees of authoritativeness, clarity and accuracy—about some of the social Web sites, uses of the sites, and some social problems, and business challenges faced by the sites. In this paper, we attempt to organize the status, uses, and issues of social Web sites into a comprehensive framework for discussing, understanding, using, building, and forecasting the future of social Web sites. 相似文献
4.
Dong-Yong Hong Dong-Hun Lee Ji-Young Lee Eun-Chae Lee Sang-Won Park Man-Ryul Lee Jae-Sang Oh 《International journal of molecular sciences》2022,23(15)
The low-density-lipoprotein receptor (LDLr) removes low-density lipoprotein (LDL), an endovascular transporter that carries cholesterol from the bloodstream to peripheral tissues. The maintenance of cholesterol content in the brain, which is important to protect brain function, is affected by LDLr. LDLr co-localizes with the insulin receptor and complements the internalization of LDL. In LDLr deficiency, LDL blood levels and insulin resistance increase, leading to abnormal cholesterol control and cognitive deficits in atherosclerosis. Defects in brain cholesterol metabolism lead to neuroinflammation and blood–brain-barrier (BBB) degradation. Moreover, interactions between endoplasmic reticulum stress (ER stress) and mitochondria are induced by ox-LDL accumulation, apolipoprotein E (ApoE) regulates the levels of amyloid beta (Aβ) in the brain, and hypoxia is induced by apoptosis induced by the LDLr defect. This review summarizes the association between neurodegenerative brain disease and typical cognitive deficits. 相似文献
5.
Ahn Eunyeong Lee Jimin Jeon Young-Hee Choi Sang-Won Kim Eunjung 《Food science and biotechnology》2017,26(6):1693-1702
Food Science and Biotechnology - Despite with accumulating evidences on the anti-diabetic effects of mulberry branch (MB), the major active component for the activity has not been known. Oral... 相似文献
6.
The global oil market is experiencing a structural shift. Faced with a rapid price decline, large oil-producing countries had decided to protect their market share, with the hopes of permanently removing expensive supply from the market. Meanwhile, the ability of the US shale oil producers to respond quickly to positive price signals puts downward pressure on prices. On the demand side, advances in renewable technology and the continued effort to curb consumption of fossil fuel conspire to inhibit long-run growth.1 These factors suggest that the current down-cycle may continue for an extended period of time or even invoke another down-cycle. 相似文献
7.
Sang-Won Min Soon-Ryul Nam Sang-Hee Kang Jong-Keun Park 《Electrical Engineering (Archiv fur Elektrotechnik)》2007,89(7):525-533
This paper proposes a fault location algorithm for cross-bonded cables. The algorithm uses nonlinear equations that describe
the voltage drops between both ends of core conductors and sheaths in terms of the phase voltages and currents of both the
local and remote ends. Arranging these equations about the sheath currents yields a sheath impedance matrix, which is singular
independently of the fault distance. Due to this singularity, the equations have no solution or an infinite number of solutions.
The proposed algorithm finds the condition for which a solution to the equations exists. Since the equation of the condition
is linear and explicit, the fault location can be found easily. Test results indicate that the algorithm accurately estimates
the fault distance regardless of fault impedance, fault type, and fault section. 相似文献
8.
Sang-Won Myoung Sung-Il Jung Eun-Hee Kim Yeon-Gil Jung Yoon-Suk Nam Woon-Sub Kyoung 《Progress in Organic Coatings》2009,64(2-3):311-316
The effects of amounts and particle size of nonmetallic minerals on the rheological behavior of the slurry and microstructure evolution of an eco-friendly functional wallpaper were investigated to optimize preparation parameters. Mixed binder system was used to prepare the wallpaper. Nonmetallic minerals such as TiO2, CaCO3, illite, pearl, and small amounts of graphite were mixed with the binder and then ball milled for 12 h. The particle size of the starting materials was controlled by the milling process, showing a significant reduction in particle size. Mixed slurries coated on base paper (substrate) were dried and pressed at 150 °C, forming seven layers. The reduced particle size increases the amounts of the nonmetallic minerals in the slurry, which causes an increase in viscosity and inhibits powder sedimentation. Despite the increase in the amounts of nonmetallic minerals, the nonmetallic minerals are homogeneously dispersed, as confirmed by microstructure and EDS mapping. The nonmetallic minerals provide the wallpaper with eco-friendly functions such as unit-infrared emission and antifungal ability, and improve the deodorization ratio and decrease the emission ratio of TVOC and HCHO compared with conventional wallpaper. 相似文献
9.
The microbes ofPseudomonas putida (KCTC1768) were fixed on the biofilter-packing media comprising an equivolume mixture of granular activated carbon (GAC)
and compost, by recycling the liquid medium containing incubatedPseudomonas putida (KCTC1768). A biofilter experiment was performed to observe its transient behavior under the operating condition of 2,180
ppmv of ethanol-inlet concentration and 158 g/m3/h of ethanol-inlet load for the five consecutive temperature-stages of operation ranging from 25 °C to 40 °C. For the five
temperaturestages of operation their removal efficiencies were measured and were compared with each other. The optimum operating
temperature of the biofilter turned out to beca. 30 °C, which was consistent with the previous experimental result of Lim and Park. However, the optimum incubation-temperatures
ofPseudomonas putida (KCTC1768) and the equivalent (i.e., NCIMB8858) were announced to be of 26 °C and 25 °C by Korea Collection for Type Cultures
(KCTC) and National Collections of Industrial, Food and Marine Bacteria (NCIMB), respectively. It was also confirmed by the
experiment in which the microbes were incubated in the same liquid medium as in the previous work of Lim and Park at temperature
ranging from 20 °C to 40 °C and their growth rates were subsequently measured. Thus, the optimum operating temperature of
a biofilter inoculated withPseudomonas putida (KCTC 1768) was proved to be 30 °C, which was higher than its optimum incubation-temperature byca. 5 °C 相似文献
10.
Byung Sup Rho Saekyoung Kang Han Seo Cho Hyo-Hoon Park Sang-Won Ha Byoung-Ho Rhee 《Lightwave Technology, Journal of》2004,22(9):2128-2134
In this paper, a new architecture for a chip-to-chip optical interconnection system is demonstrated that can be applied in a waveguide-embedded optical printed circuit board (PCB). The experiment used 45/spl deg/-ended optical connection rods as a medium to guide light paths perpendicularly between vertical-cavity surface-emitting lasers (VCSELs), or photodiodes (PDs) and a waveguide. A polymer film of multimode waveguides with cores of 100/spl times/65 /spl mu/m was sandwiched between conventional PCBs. Via holes were made with a diameter of about 140 /spl mu/m by CO/sub 2/-laser drilling through the PCB and the waveguide. Optical connection rods were made of a multimode silica fiber ribbon segment with a core diameter of 62.5 and 100 /spl mu/m. One end of the fiber segment was cut 45/spl deg/ and the other end 90/spl deg/ by a mechanical polishing method. These fiber rods were inserted into the via holes formed in the PCB, adjusting the insertion depth to locate the 45/spl deg/ end of rods near the waveguide cores. From this interconnection system, a total coupling efficiency of about -8 dB was achieved between VCSELs and PDs through connection rods and a 2.5 Gb/s /spl times/ 12-ch data link demonstrated through waveguides with a channel pitch of 250 /spl mu/m in the optical PCB. 相似文献