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981.
Takashi Nagatani 《Physica A》2009,388(14):2911-2921
We study the dynamic behavior of vehicular traffic through a series of traffic lights on selected paths in a two-dimensional (2d) traffic network. The city traffic network is made of one-way perpendicular streets arranged in a square lattice with traffic signals where vertical streets are oriented upwards and horizontal streets are oriented rightwards. A vehicle moves through the series of signals on a path selected by the driver. The selected path is one of the straight, zigzag, and random paths in a 2d traffic network. The vehicular motion on a selected path is presented by the nonlinear-map model. Vehicular traffic exhibits very complex behavior with varying selected paths, cycle times, and vehicular density. The dependence of the arrival time on cycle time, selected path, and density is clarified for 2d city traffic. 相似文献
982.
Angular and spatial profiles of undulator radiation have been investigated to derive a universal function that evaluates the brilliance of undulator radiation and takes into account the effects of electron beam emittance and energy spread. It has been found that the effects of energy spread on the angular divergence and source size can be expressed by simple analytic expressions, and a universal brilliance function has been derived by convolution with the electron beam distribution functions. Comparisons with numerical results have been carried out to show the validity and applicability of the universal function. 相似文献
983.
Takashi Harumoto Javed Iqbal Xiaofang Liu Ji Shi Yoshio Nakamura Ronghai Yu 《Applied Physics A: Materials Science & Processing》2009,97(1):211-215
Co doped SnO2 nanoparticles have been prepared via a wet chemical method with different precipitation processes. The structure and morphology
of Co doped SnO2 nanoparticles demonstrate that the nanoparticles are in a rutile single phase and uniform, respectively. X-ray photoelectron
spectroscopy shows that the Co dopants are in 2+ oxidation valence state and doped ∼2 atm% in SnO2 nanoparticles. Moreover, Raman spectroscopy further confirms that Co doped SnO2 nanoparticles have single phase crystallinity without forming any extra modes related to secondary phases. The magnetic measurements
reveal that all nanoparticles exhibit room temperature ferromagnetism (RTFM) due to the presence of disorders and defects
introduced by hydroxyls in the crystal structure. In addition, it has been clearly observed that the saturated magnetic moments
are strongly affected by the precipitation processes which control the incorporation of hydroxyls into the lattice. 相似文献
984.
Kazuaki Sakoda Takashi Kuroda NaokiI keda Takaaki Mano Yoshimasa Sugimoto Tetsuyuki Ochiai Keiji Kuroda Shunsuke Ohkouchi Nobuyuki Koguchi Kiyoshi Asakawa 《中国光学快报(英文版)》2009,7(10):879-881
We fabricate photonic crystal slab microcavities embedded with GaAs quantum dots by electron beam lithography and droplet epitaxy. The Purcell effect of exciton emission of the quantum dots is confirmed by the micro photoluminescence measurement. The resonance wavelengths, widths, and polarization are consistent with numerical simulation results. 相似文献
985.
A method to characterize attosecond extreme ultra violet (XUV) pulses from photoelectron spectra of atoms is presented. A pump pulse prepares a coherent superposition of two atomic bound states, from which photoionization takes place after variable time delays by the attosecond XUV pulse. Information on the spectral phase of the attosecond XUV pulse is extracted from the analysis of photoelectron spectra as a function of photoelectron energy and time delay. Together with information on the spectral intensity obtained from a separate optical measurement, a temporal shape of the attosecond XUV pulse can be precisely reconstructed. After the theoretical formulation of the problem, we present numerical examples for H atom and show that, depending on the choice of energy separation of two bound states, a different accuracy is reached to characterize attosecond XUV pulses. 相似文献
986.
Mariame A. Hassan Loreto B. Feril Kosho Suzuki Nobuki Kudo Katsuro Tachibana Takashi Kondo 《Ultrasonics sonochemistry》2009,16(3):372-378
Three novel lipid-shell-type microbubbles (MBs), AS-0100, BG6356A and BG6356B, have been evaluated for their impact on ultrasound (US)-induced cell death and free radicals production. Previously studied and well-characterized US exposure conditions were employed in which human myelomonocytic lymphoma U937 cells were exposed to 1 MHz pulsed US beam (0.3 W/cm2, 10% duty factor) for 1 min with or without MBs. Three different concentrations of each MB were used. Apoptosis and cell lysis were assessed by examining phosphatidylserine externalization and by counting viable cells, respectively, 6 h post-exposure. Free radicals production and scavenging activities were evaluated using electron paramagnetic resonance (EPR)-spin trapping. The results showed that only AS-0100 and BG6356A were able to enhance the US-induced apoptosis, mainly by increasing the secondary necrosis. Apoptosis and cell lysis seemed to depend more on mechanical forces exerted by oscillating MBs while free radicals played a trivial role. BG series MBs exhibited pronounced scavenging activities. Generally, despite the need for further optimization, AS-0100 and BG6356A appear to be promising as adjuncts in cases where US-induced cell death is required. 相似文献
987.
988.
Saburo Yuasa Masaru Kawashima Takashi Sakurai 《Proceedings of the Combustion Institute》2009,32(2):1929-1936
To examine the pyrophoric characteristics of Mg powder, we generated ultra-fine Mg particles (average particle diameter: about 0.3 μm) without an original oxide coat in an Ar stream. The ignition of the powder was measured by using the impinging O2/N2 mixture streams over a wide range of the experimental parameters: pressure, oxygen concentration and velocity of the streams. The Mg powder was found to ignite even at room temperature. The spontaneous ignition temperatures in the range of 278 324 K were insensitive to all the experimental parameters. The ignition delay time had a tendency to decrease with increasing experimental parameters.The ignition process of the Mg powder was found to be controlled by the surface reaction rate without an oxide coat. We proposed a new ignition hypothesis considering a critical oxide thickness on the Mg powder particles at the transition temperature from protective to non-protective nature: that is, the ignition of the Mg powder occurs when the powder temperature rises above the transition temperature before surface reactions form a protective oxide coat with the critical thickness on the individual particle surfaces. According to this hypothesis, an ignition model of Mg powder cluster was developed, and the relation between the spontaneous critical ignition temperature and the ultra-fine powder size, depending on the critical thickness of the protective oxide coat, was clarified. The critical oxide thickness was estimated. 相似文献
989.
Takashi Nagatani 《Physics letters. A》2009,373(5):536-539
When a vehicle moves through a series of green lights with avoiding red signals in the traffic network, the travel time has a minimal value and the vehicle draws a characteristic trajectory. We study the trajectories (green-light paths) of a vehicle for various values of both cycle time and split at the synchronized and random-phase strategies. The trajectory depends highly on both signal's characteristics and control strategy. We clarify the dependence of green-light paths on both cycle time and split. At the random phase strategy, the vehicle draws a trajectory of the random walk. It is shown where the vehicle arrives if a driver selects the green-light path. 相似文献
990.
Nishimura Yuya Nishimura Sohei Nishimura Tsuyoshi Yano Takashi 《Applied Acoustics》2009,70(9):1160-1167
Casement windows consisted of two wooden frames that can be opened and closed at various angles are widely used in developing countries with tropical climates. However, an annual increase in a number of motorcycles and automobiles and traffic noise level these countries have rendered these windows to be useless. In this paper, we present a model for manufacturing windows which are suitable for the developing tropical countries. These windows are capable of ventilating, regulating sunlight, protecting against coldness, and reducing traffic noise and fumes from motor vehicles. The ventilation and soundproofing unit hold an importance place in the design of the windows and are calculated using the wave equation and observations of higher-order mode waves. In order to maximize the soundproofing ability, the selection of size and placement of input and output openings in such a way that would minimize the effects of higher-order mode waves are considered in details. 相似文献