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161.
We study the traffic states and jams induced by a slowdown of vehicles in a single-lane highway. The two-stage optimal velocity model is used in which the optimal velocity function has two turning points. The fundamental (flow-density) diagrams are calculated. At low density, the flow (current) increases linearly with density, while it saturates at some values of intermediate density. When the flow saturates, the discontinuous front (stationary shock wave) appears before or within the section of slowdown. The values of saturated flow are determined by the extreme values of theoretical current curves. The relationship between the densities is derived before and after the discontinuity. 相似文献
162.
Jian-guang Yang Sheng-hai Yang Takeshi Okamoto Takeshi Bessho Shigeru Satake Ryoichi Ichino Masazumi Okido 《Surface science》2006,600(24):L318-L320
Using aqueous–organic interface (water–oleic acid) reduction of Cu2+ by ascorbic acid, hydrophobic copper monolayer and copper particles have been prepared and characterized. The resultant monolayer could be transferred from the interface onto solid substrate or be dissolved to yield an organosol and copper nanoparticles. 相似文献
163.
Tomohiro Iwasaki Maiko Takahara Ryoichi Sonoda Satoru Watano 《Particle & Particle Systems Characterization》2007,24(3):236-241
This paper details an investigation into the enhancement of the water dissolution rate of mefenamic acid (MA) by means of a dry grinding treatment. The physico‐chemical properties of the ground MA particles were analyzed by measurements of specific surface area, powder X‐ray diffraction patterns, differential scanning calorimetry thermograms and infrared spectra, and the effects of the change in the physico‐chemical properties (especially, crystalline structure) on the dissolution rate were studied. The polymorphic transition from Form I (original) to II and the change of the molecular structure of MA did not occur in the grinding treatments. However, the specific surface area of the MA particles increased, and the crystallinity decreased (i.e., the amorphization level increased) as the grinding progressed. Hydrogen bonds formed between the carboxyl groups of the opposed asymmetric MA molecules were broken gradually after the grinding limit was attained in the grinding system, resulting in an effective improvement of the initial dissolution rate. 相似文献
164.
In this paper, water jet has been used to achieve a reduction in the magnitude of the excavation torque, also known as the torsional resistance, imparted on the cutting wing of an excavation machine during rotational excavation of cohesionless soils. This was accomplished by injecting a controlled water jet along the front plane of the cutting wing during the excavation of a model sandy ground. Experimental excavation was performed on compacted completely saturated sand samples using a prototype excavation machine and the torque required for excavation was measured. Within the experimental limitations, the results showed that water jet could successfully be used to reduce torque during excavation of dense sandy soils. 相似文献
165.
166.
A general methodology is presented to perform direct numerical simulations of particle dispersions in a shear flow with Lees-Edwards periodic boundary conditions. The Navier-Stokes equation is solved in oblique coordinates to resolve the incompatibility of the fluid motions with the sheared geometry, and the force coupling between colloidal particles and the host fluid is imposed by using a smoothed profile method. The validity of the method is carefully examined by comparing the present numerical results with experimental viscosity data for particle dispersions in a wide range of volume fractions and shear rates including nonlinear shear-thinning regimes. 相似文献
167.
Novel electron-transfer-induced intermolecular [2+2] cycloaddition reactions between an aliphatic cyclic enol ether and several unactivated olefins have been demonstrated on the basis of the aromatic "redox tag" strategy. The aromatic "redox tag" was oxidized during the formation of the cyclobutane ring, affording the relatively long-lived aromatic radical cation, which was then reduced to complete the overall reaction that constructed the corresponding [2+2] cycloadducts. The aromatic "redox tag" was also found to facilitate electron-transfer-induced cycloreversion reactions of cyclobutane rings. 相似文献
168.
We propose a compact compound-eye projector using superresolved projection. The optics are composed of multiple small suboptics (units) to reduce their thickness in the projector. Each of the suboptics adds a subpixel shift to a projected image for superresolved projection and has a color filter or a dispersive element for multicolor projection. The projected images in the units are determined via a model of the system in preprocessing. The images are projected by the suboptics and superimposed on a screen. In this Letter, we describe the system model and show the simulation results. 相似文献
169.
Yu Shiratsuchi Shin-ichi KawaharaHayato Noutomi Kazuto ArakawaHirotaro Mori Ryoichi Nakatani 《Journal of magnetism and magnetic materials》2011,323(5):579-586
The effect of the crystalline quality of ultrathin Co films on perpendicular exchange bias (PEB) has been investigated using a Au/Co/Au/α-Cr2O3 thin film grown on a Ag-buffered Si(1 1 1) substrate. Our investigation is based on the effect of the Au spacer layer on the crystalline quality of the Co layer and the resultant changes in PEB. An α-Cr2O3(0 0 0 1)layer is fabricated by the thermal oxidization of a Cr(1 1 0) thin film. The structural properties of the α-Cr2O3(0 0 0 1) layer including the cross-sectional structure, lattice parameters, and valence state have been investigated. The fabricated α-Cr2O3(0 0 0 1) layer contains twin domains and has slightly smaller lattice parametersthan those of bulk-Cr2O3. The valence state of the Cr2O3(0 0 0 1) layer is similar to that of bulk Cr2O3. The ultrathin Co film directly grown on the α-Cr2O3(0 0 0 1) deposited by an e-beam evaporator is polycrystalline. The insertion of a Au spacer layer with a thickness below 0.5 nm improves the crystalline quality of Co, probably resulting in hcp-Co(0 0 0 1). Perpendicular magnetic anisotropy (PMA) appears below the Néel temperature of Cr2O3 for all the investigated films. Although the PMA appears independently of the crystallinequality of Co, PEB is affected by the crystalline quality of Co. For the polycrystalline Co film, PEB is low, however, a high PEB is observed for the Co films whose in-plane atom arrangement is identical to that of Cr3+ in Cr2O3(0 0 0 1). The results are qualitatively discussed on the basis of the direct exchange coupling between Cr and Co at the interface as the dominant coupling mechanism. 相似文献
170.