Saitama University

About: Saitama University is a education organization based out in Saitama, Japan. It is known for research contribution in the topics: Band-pass filter & Magnetization. The organization has 7620 authors who have published 13432 publications receiving 239945 citations. The organization is also known as: Saitama Daigaku.

Dense 3D Reconstruction with an Uncalibrated Active Stereo System

Abstract: In this paper, we describe a novel uncalibrated active stereo system using coded structured light. Structured-light-based active stereo systems generally consist of a camera and projector that require precise precalibration. Therefore, if we can eliminate the precalibration process from the system, the user can merely place the equipment arbitrarily and directly begin scanning the objects. This will greatly improve both the convenience and practicality of the system. In order to achieve this, we propose an original self-calibration method that can be considered as a camera-to-camera self-calibration method in which one of the cameras is replaced with a projector. We also propose a simultaneous 3D reconstruction method that utilizes multiple captured stereo pairs to increase the accuracy of the 3D estimation. Further, we suggest a simple solution to eliminate the ambiguity of scaling by attaching a laser pointer to the projector, which is important for the practical use of the 3D reconstruction.

Flow Characteristics of Fluid Droplet Obtained From Air Assisted Atomizer

Abstract: Air assisted atomizer system was designed and developed for fuel injection. The present purpose is to utilize a low pressure in supplying of atomized fuel. Distilled water was used as test liquid on the experiments for the system of atomization. The results revealed air assisted atomizer had a capability to inject the test liquid in the range of the rates of 0.0019–0.00426 kg/s, with the use of air pressure supplied from 68.9 to 689 kPa. In this research, the test liquid supply pressure was kept constant and the air flow rate through the atomizer was varied over a range of air supply pressure to obtain the variation in air liquid mass flow ratio (ALR). The spray solidity was studied by taking pictures of the spray at different liquid air supply pressures. The experimental investigations suggest that spray cone angle tends to increase with increasing in air liquid mass flow ratio because the kinetic energy of the flow keeps on increasing. The solid cone spray has a pattern of penetration depth between 408–446 mm. and cone angle between 14.5–23.6°. It was observed that spray formed the solid cone at all the operating conditions.Copyright © 2011 by JSME

A Northern Sky Survey for Point-Like Sources of EeV Neutral Particles with the Telescope Array Experiment

Abstract: We report on the search for steady point-like sources of neutral particles around 10$^{18}$ eV between 2008 May and 2013 May with the scintillator surface detector of the Telescope Array experiment. We found overall no significant point-like excess above 0.5 EeV in the northern sky. Subsequently, we also searched for coincidence with the Fermi bright Galactic sources. No significant coincidence was found within the statistical uncertainty. Hence, we set an upper limit on the neutron flux that corresponds to an averaged flux of 0.07 km$^{-2}$ yr$^{-1}$ for $E>1$ EeV in the northern sky at the 95% confidence level. This is the most stringent flux upper limit in a northern sky survey assuming point-like sources. The upper limit at the 95% confidence level on the neutron flux from Cygnus X-3 is also set to 0.2 km$^{-2}$ yr$^{-1}$ for $E>0.5$ EeV. This is an order of magnitude lower than previous flux measurements.

Swarm Analysis by Using Transport Equations. VIII. Electrophoresis in a Cylindrical Positive Column

Abstract: The electrophoresis phenomenon in a cylindrical positive column has been theoretically investigated. An extensive improvement on the theory has been made from the view point of the momentum transmitted to neutral particles from charged particles on the basis of the quasi-neutral theory of the positive column recently presented by the authors. According to this, several fresh results, for example, a general expression for the pressure gradient along the axis, and dependence of the pressure gradient on the pressure and the tube radius have been obtained. In addition, a comparison between calculated and experimental characteristics has verified the diffusion cooling for positive ions predicted by the authors before.

Active control of combustion oscillations for premixed combustion systems

Abstract: Methane premixed flame is studied extensively using a swirl burner and a swirl combustion chamber. First the fundamental study for the flame properties is performed for the swirl burner. Flame configuration is analyzed by a high speed photography and Schlieren system. Then a control system is set up using MATLAB, Simulink, PPC Controller board, dSPACE, and an actuator. Two control systems are applied in the present study; one by using a mass flow control system and another by using a speaker. In the mass flow system the premixed flame is controlled by the certain threshold. In the speaker system the premixed flame is controlled on and off arbitrary using the sensor and actuator. A half frequency of the primary frequency of noise is detected to be eigen value, but is investigated where this frequency comes from. The present systems are open loop system and closed system will be established soon.