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Search Results: 1 - 10 of 120204 matches for " Yifei Wang "
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Monotonicity of Harnack Inequality for Positive Invariant Harmonic Functions
Yifei Pan,Mei Wang
International Journal of Stochastic Analysis , 2007, DOI: 10.1155/2007/39171
Abstract: A monotonicity property and a refined estimate of Harnack inequality are derived for positive solutions of the Weinstein equation.
Uniqueness for n-th order differential systems with strong singularities
Yifei Pan,Mei Wang
Electronic Journal of Differential Equations , 2010,
Abstract: Using a Lipschitz type condition, we obtain the uniqueness of solutions for a system of n-th order nonlinear ordinary differential equations where the coefficients are allowed to have singularities.
A uniqueness result for ordinary differential equations with singular coefficients
Yifei Pan,Mei Wang
Electronic Journal of Differential Equations , 2009,
Abstract: We consider the uniqueness of solutions of ordinary differential equations where the coefficients may have singularities. We derive upper bounds on the order of singularities of the coefficients and provide examples to illustrate the results.
A uniqueness result on ordinary differential equations with singular coefficients
Yifei Pan,Mei Wang
Mathematics , 2008,
Abstract: We consider the uniqueness of solutions of ordinary differential equations where the coefficients may have singularities. We derive upper bounds on the the order of singularities of the coefficients and provide examples to illustrate the results.
On the monotonicity of positive invariant harmonic functions in the unit ball
Yifei Pan,Mei Wang
Mathematics , 2007,
Abstract: A monotonicity property of Harnack inequality is proved for positive invariant harmonic functions in the unit ball.
A Hopf's Lemma for Higher Order Differential Inequalities and Its Applications
Yifei Pan,Mei Wang,Yu Yan
Mathematics , 2012,
Abstract: We establish a sequential Hopf's Lemma for higher order differential inequalities in one variable and give some applications of this result.
Uniqueness Theorems for Ordinary Differential Equations with H?lder Continuity
Yifei Pan,Mei Wang,Yu Yan
Mathematics , 2012,
Abstract: We study ordinary differential equations of the type $u^{(n)}(t)=f(u(t))$ with initial conditions $u(0) = u'(0) =... = u^{(m-1)}(0) = 0 $ and $u^{(m)}(0) \neq 0$ where $m \geq n$, no additional assumption is made on $f$. We establish some uniqueness results and show that $f$ is always H\"older continuous.
Abrasion Behavior of High Manganese Steel under Low Impact Energy and Corrosive Conditions
Du Xiaodong,Sun Guodong,Wang Yifei,Wang Jianfeng,Yang Haoyu
Advances in Tribology , 2009, DOI: 10.1155/2009/685648
Abstract: The abrasion behavior of high manganese steel is investigated under three levels of impact energy in acid-ironstone slurry. The wear test was carried out by an MLDF-10 tester with impact energy of 0.7 J, 1.2 J, and 1.7 J. The impact abrasion property of high manganese steel in corrosive condition was compared according to the wear mass loss curves. The wear mechanism was analysed by the SEM analysis of the worn surface and the optical metallographic analysis of the vertical section to the wear surface. The results show that the impact energy has a great effect on the impact corrosion and abrasion properties of it. Its abrasion mechanism in corrosive condition is mainly microplough and breakage of plastic deformed ridges and wedges under the impact energy of 0.7 J. It is mainly the spelling of plastic deformed ridges and wedges under 1.2 J and the spalling of the work-hardening layer under 1.7 J after a long time testing.
Difference in metapopulation structure and dynamics of two species of coexistent melitaeine butterflies
Yifei Wang,Jiejun Chen,Rongjiang Wang,Guangchun Lei,Rumei Xu
Chinese Science Bulletin , 2003, DOI: 10.1007/BF03183945
Abstract: According to investigation on two species of melitaeine butterflies in Yanjiaping Village, Chicheng County, Hebei Province, China, between 1998–2002, together with the use of 1–10000 contour map of the local area, some conclusions are shown by the SPSS and GIS analysis of data obained from GPS: (1) The two species of melitaeine butterflies have different metapopulation structures.M. phoebe is a source-sink metapopulation, whileE. aurinia is a classical metapopulation, supporting the analytic result from our former genetic research. (2) The two species of melitaeine butterflies exhibit different trends of population dynamics.M. phoebe source-sink metapopulation is very unsteady, and is always small, thus has a tendency to go extinct gradually. ButE. aurinia classical metapopulation is stable, and has maintained a larger population size. Therefore, it stands a better chance of long-term survival. (3) The two species of melitaeine butterflies are significantly related in both patch occupancy and local population size. (4) The effect of isolation is significant on the metapopulations of these two species of melitaeine butterflies, consistent with the classical theories, whereas the effect of patch area is not significant on the metapopulations of these two species of melitaeine butterflies, which is inconsistent with the classical theories. Therefore, other factors, such as habitat quality, should be considered for their influences on metapopulations.
LC-MS-MS Analysis and the Antioxidant Activity of Flavonoids from Eggplant Skins Grown in Organic and Conventional Environments  [PDF]
Ajay P. Singh, Yifei Wang, Rachel M. Olson, Devanand Luthria, Gary S. Banuelos, Sajeemas Pasakdee, Nicholi Vorsa, Ted Wilson
Food and Nutrition Sciences (FNS) , 2017, DOI: 10.4236/fns.2017.89063
Abstract: Eggplant fruits are known to contain different classes of phenolic phytochemicals (flavonols, phenolic acids, and anthocyanins) that can exert beneficial effects on human health. This study developed methods for the qualitative and quantitative composition analysis of phenolic compounds in the skin of eggplant fruits harvested following conventional and certified organic farming conditions. Eggplant skin was extracted using aqueous methanol prior to phenolic profiling with UHPLC-ESI-MS-MS. Eggplant skin extracts yielded a profile of 16 phenolic acids, 4 anthocyanins, and 11 flavonols, the first report of quercetin-3-diglucoside, myricetin-3-neohesperidoside, myricetin-3-galactoside, kaempferol-3,7-diglucoside, kaempferol-diglucoside and quercetin-3-rhamnoside. Polyphenolic extracts from all sources potently delayed the cupric ion-mediated lag-time for LDL lipid oxidation and protected Apo-B100 proteins against oxidative modification. Organic growing environment positively influences eggplant skin extract phenolic profile but not antioxidant capacity. In conclusion, eggplant skin has a robust profile of phenolic phytochemicals with excellent antioxidant properties.
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