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141.
142.
Ho Jung Paik 《General Relativity and Gravitation》2008,40(5):907-919
The angular momentum of the Earth produces gravitomagnetic components of the Riemann curvature tensor, which are of the order
of 10−10 of the Newtonian terms arising from the mass of the Earth. Due to the dragging of the local inertial frame by the spinning
Earth, there are also secular terms, which grow in time. These fields can be detected in principle by a set of orbiting superconducting
gravity gradiometers. The Riemann tensor components for various spacecraft orientations have been computed and the principle
of detecting the gravitomagnetic tidal force has been published. In this paper, we review the conclusions of the earlier analyses
and discuss the feasibility of the gravity gradiometer experiment. 相似文献
143.
Kim DJ Lee KB Chi YS Kim WJ Paik HJ Choi IS 《Langmuir : the ACS journal of surfaces and colloids》2004,20(19):7904-7906
Biosilicification in diatoms is achieved by specific interactions between silaffins, composed of polypeptides and long-chain polyamines, and silicic acid derivatives. The polycondensation of silicic acids is reported to be catalyzed by the long-chain polyamines that mainly contain tertiary N-methylpropyleneimine moieties. In this report, we utilized a tertiary amine-containing polymer, poly(2-(dimethylamino)ethyl methacrylate) (poly(DMAEMA)), as a surface-grafted, biomimetic counterpart of the long-chain polyamines in silaffins and demonstrated that the surface-initiated polycondensation of silicic acids, leading to the formation of silica thin films, proceeded smoothly on surfaces presenting poly(DMAEMA), where poly(DMAEMA) was grown from gold surfaces by surface-initiated, atom transfer radical polymerization. The formed silica film was characterized by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, atomic force microscopy, and scanning electron microscopy. 相似文献
144.
A stereoscopic PIV (Particle Image Velocimetry) technique has been employed to measure the 3 dimensional flow structure of
turbulent wake behind a marine propeller with 5 blades. The out-of-plane velocity component was measured using particle images
captured simultaneously by two CCD cameras installed in the angular displacement configuration. 400 instantaneous velocity
fields were acquired for each of four different blade phases of 0°, 18°, 36° and 54°. They were ensemble averaged to investigate
the spatial evolution of propeller wake in the near wake region up to one propeller diameter (D) downstream. The phase-averaged
velocity fields show clearly the viscous wake formed by the boundary layers developed along both surfaces of the blade. Tip
vortices were generated periodically and the slipstream contraction occurs in the near-wake region. The out-of-plane velocity
component has large values at the locations of tip and trailing vortices. With going downstream, the axial turbulence intensity
and the strength of tip vortices were decreased due to the viscous dissipation, turbulence diffusion and blade-to-blade interaction.
The difference in the mean velocity fields measured by SPIV and 2-D PIV methods was about 5% ≈ 10%. However, the 2-D PIV results
also give sufficient information on propeller wake beyond the region of X/D=0.2. 相似文献
145.
Three-component velocity field measurements of propeller wake using a stereoscopic PIV technique 总被引:1,自引:0,他引:1
Sang?Joon?LeeEmail author Bu?Geun?Paik Jong?Hwan?Yoon Choung?Mook?Lee 《Experiments in fluids》2004,36(4):575-585
A stereoscopic PIV (Particle Image Velocimetry) technique was used to measure the three-dimensional flow structure of the turbulent wake behind a marine propeller with five blades. The out-of-plane velocity component was determined using two CCD cameras with an angular displacement configuration. Four hundred instantaneous velocity fields were measured for each of four different blade phases, and ensemble averaged in order to find the spatial evolution of the propeller wake in the region from the trailing edge up to one propeller diameter (D) downstream. The influence of propeller loading conditions on the wake structure was also investigated by measuring the velocity fields at three advance ratios (J=0.59, 0.72 and 0.88). The phase-averaged velocity fields revealed that a viscous wake formed by the boundary layers developed along the blade surfaces. Tip vortices were generated periodically and the slipstream contracted in the near-wake region. The out-of-plane velocity component and strain rate had large values at the locations of the tip and trailing vortices. As the flow moved downstream, the turbulence intensity, the strength of the tip vortices, and the magnitude of the out-of-plane velocity component at trailing vortices all decreased due to effects such as viscous dissipation, turbulence diffusion, and blade-to-blade interaction. 相似文献
146.
In this paper, we study the expectation values of topological invariants of the Vietoris–Rips complex and ?ech complex for a finite set of sample points on a Riemannian manifold. We show that the Betti number and Euler characteristic of the complexes are Lipschitz functions of the scale parameter and that there is an interval such that the Betti curve converges to the Betti number of the underlying manifold.
相似文献147.
Jonghwan Jegal No-June Park Beom-Geun Jo Tae-Young Kim Sim-Kyu Bong Sangho Choi Jin-Hyub Paik Jung-Won Kim Su-Nam Kim Min Hye Yang 《Molecules (Basel, Switzerland)》2021,26(7)
Plants of the genus Wikstroemia are used in Chinese traditional medicine to treat inflammatory diseases, such as arthritis, bronchitis, and pneumonia. The present study was designed to determine whether Wikstroemia ganpi (Siebold and Zucc.) Maxim. offers a potential means of treating 2,4-dinitrochlorobenzene (DNCB)-induced atopic dermatitis (AD) in mice. Symptoms such as redness, edema, and keratinization in AD mice induced by DNCB were alleviated by the co-application of an ethanolic extract of W. ganpi for 2 weeks. The severity of skin barrier function damage was evaluated by measuring TEWL (transepidermal water loss). TEWLs of DNCB sensitized mouse dorsal skin were reduced by the application of a W. ganpi ethanolic extract, and skin hydration was increased. In addition, the infiltration of inflammatory cells into the dermis was significantly reduced, as were blood levels of IgE and IL-4, which play an important role in the expression of AD. The results of this experiment suggest that W. ganpi is a potential therapeutic agent for AD. 相似文献
148.
A dispersion technology for Ni particles suspended in a non-aqueous medium based on the quantitative evaluation of surface acid-base properties of Ni particles is described. A quantitative analysis of surface acid-base properties of Ni particles was performed using non-aqueous titration. Dimethylamino ethanol and acetic acid were used as probe molecules to detect surface acid-base amounts of Ni particles. The dispersion system was designed on the basis of the amounts of surface acid-base sites on the Ni particle surface. Rheological behavior and agglomerate particle size data demonstrate that the dispersion stability of the designed Ni suspension is markedly improved, as expected. Therefore, the design strategy to improve the dispersion stability of Ni particles was successful. This strategy is expected to be applicable to dispersion systems of other particles suspended in a non-aqueous medium. 相似文献
149.
Chon CH Paik S Tipton JB Kihm KD 《Langmuir : the ACS journal of surfaces and colloids》2007,23(6):2953-2960
A microfabricated linear heater array operating in a constant voltage mode has been used to study the effect of nanoparticle size on the evaporation and dryout characteristics of strongly pinned nanofluid droplets. Four different nanofluids have been tested, containing 2-nm Au, 30-nm CuO, 11-nm Al2O3, and 47-nm Al2O3 nanoparticles, each of 5-muL droplets with 0.5 vol % in water. Nanofluid droplets show strong pinning along the droplet perimeter and, upon evaporation, leave a ring-shaped nanoparticle stain. Particle size is seen to have a clear and strong effect on the dryout stain pattern, while heater temperature seems to have little effect. With the assumption of axi-symmetry, tomographic deconvolution of measured data from the linear heater array allows for examination of the spatially and temporally resolved temperature and heat flux characteristics of the evaporating nanofluid droplets. 相似文献
150.