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Search Results: 1 - 10 of 533 matches for " Toshihiko Kawabe "
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A Micromixer Using the Taylor-Dean Flow: Effect of Inflow Conditions on the Mixing  [PDF]
Toshihiko Kawabe, Yasutaka Hayamizu, Shinichiro Yanase, Takeshi Gonda, Shinichi Morita, Shigeru Ohtsuka, Kyoji Yamamoto
Open Journal of Fluid Dynamics (OJFD) , 2014, DOI: 10.4236/ojfd.2014.45037
Abstract: Chaotic mixing in a curved-square channel flow is studied experimentally and numerically. Two walls of the channel (inner and top walls) rotate around the center of curvature and a pressure gradient is imposed in the direction toward the exit of the channel. This flow is a kind of Taylor-Dean flows. There are two parameters dominating the flow, the Dean number De (∝ the pressure gradient or the Reynolds number) and the Taylor number Tr (∝ the angular velocity of the wall rotation). In the present paper, we analyze the physical mechanism of chaotic mixing in the Taylor-Dean flow by comparing experimental and numerical results. We produced a micromixer model of the curved channel several centimeters long with square cross section of a few millimeters side. The secondary flow was measured using laser induced fluorescence (LIF) method to examine secondary flow characteristics. We also performed three-dimensional numerical simulations for the exactly same configuration as the experimental system to study the mechanism of chaotic mixing. It is found that good mixing performance is achieved for the case of De ≤ 0.1Tr, and that mixing efficiency changes according to the difference in inflow conditions. The flow is studied both experimentally and numerically, and both results agree with each other very well.
A Micromixer Using the Taylor-Dean Flow: Effects of Aspect Ratio and Inflow Condition on the Mixing  [PDF]
Yasutaka Hayamizu, Toshihiko Kawabe, Shinichiro Yanase, Takeshi Gonda, Shinichi Morita, Shigeru Ohtsuka, Kyoji Yamamoto
Open Journal of Fluid Dynamics (OJFD) , 2015, DOI: 10.4236/ojfd.2015.53027
Abstract: Chaotic mixing in three different types of curved-rectangular channels flow has been studied experimentally and numerically. Two walls of the channel (inner and top walls) rotate around the center of curvature and a pressure gradient are imposed in the direction toward the exit of the channel. This flow is a kind of Taylor-Dean flow. There are two parameters dominating the flow, the Dean number De (∝ the pressure gradient or the Reynolds number) and the Taylor number Tr (∝ the angular velocity of the wall rotation). In this paper, we analyze the physical mechanism of chaotic mixing in the Taylor-Dean flow by comparing experimental results and numerical ones. We produced three micromixer models of the curved channel, several centimeters long, with rectangular cross-section of a few millimeters side. The secondary flow is measured using laser induced fluorescence (LIF) method to examine secondary flow characteristics. Also we performed three-dimensional numerical simulations with the open source CFD solver, OpenFOAM, for the same configuration as the experimental system to study the mechanism of chaotic mixing. It is found that good mixing performance is obtained in the case of De ≤ 0.1 Tr, and it becomes more remarkable when the aspect ratio tends to large. And it is found that the mixing efficiency changes according to the aspect ratio and inflow condition.
Robust MPC Method for BMI Based Wheelchair  [PDF]
Tohru Kawabe
Intelligent Control and Automation (ICA) , 2011, DOI: 10.4236/ica.2011.24039
Abstract: In this paper, robust MPC (Model Predictive Control) with adaptive DA converter method for the wheelchair using EEG (Electroencephalogram) based BMI (Brain Machine Interface) is discussed. The method is developed to apply to the obstacle avoidance system of wheelchair. This paper is the 1st stage for the development of the BMI based wheelchair in practical use. The robust MPC method is realized by using the minimax optimization with bounded constraint conditions. Some numerical examples are also included to demonstrate the effectiveness of the proposed methodas the former stage of the real experiments.
Treating Depression with the Mephenesin Analog Skeletal Muscle Relaxant Methocarbamol  [PDF]
Toshihiko Numazawa
Open Journal of Depression (OJD) , 2016, DOI: 10.4236/ojd.2016.54005
Abstract: It is difficult to treat depression because there is no established method for treatment. Many drugs have been developed by Pharmaceutical companies to treat depression. Depression affects many patients. It was necessary to focus on “meprobamate” which was once said to be a magic drug. It was found that “methocarbamol” is more suitable for treating depression than “meprobamate”.
Desalination of Seawater by Liquid Columns and Decompression Boiling (Recovery of Condensation Latent Heat)  [PDF]
Toshihiko Shakouchi
Journal of Water Resource and Protection (JWARP) , 2018, DOI: 10.4236/jwarp.2018.108046
Abstract: In this study, the concept of a new seawater desalination method and equipment using liquid columns of seawater and desalinated fresh water, decompression boiling and evaporation, condensation, and recovery of condensation latent heat are proposed. The equipment consists of seawater and freshwater columns approximately 10 m high with top spaces. The pressure of the top space, the evaporation and condensation area, of the seawater column, for example, is reduced approximately 30 mmHg (abs.) using the seawater column, after which it is heated from the general seawater temperature of 25°C to 30°C to boil and evaporate the seawater. The vapor is cooled by the seawater at approximately 25°C in a heat exchanger, and then, it is condensed and sent to the fresh water column. At this time, the condensation latent heat is recovered to preheat the newly flowing seawater. The evaporation or condensation rate, namely, the production rate of freshwater, by the new desalination equipment is also estimated by the results of the existing quadruplex effect vacuum evaporator used in the salt production industry. This new desalination method and its associated equipment also can be used to purify polluted water and waste water.
Slip Suppression of Electric Vehicles Using Sliding Mode Control Method  [PDF]
Shaobo Li, Tohru Kawabe
Intelligent Control and Automation (ICA) , 2013, DOI: 10.4236/ica.2013.43038
Abstract: This paper presents a slip suppression controller using sliding mode control method for electric vehicles which aims to improve the control performance and the energy conservation by controlling the slip ratio of wheel. In this method, a robust sliding mode controller against the model uncertainties is designed to obtain the maximum driving force by suppressing the slip ratio. The numerical simulations for one wheel model under variations in mass of vehicle and road condition are performed and demonstrated to show the effectiveness of the proposed method.
Continuous regional arterial infusion therapy with gabexate mesilate for severe acute pancreatitis
Yoshifumi Ino, Yoshiyuki Arita, Tetsuro Akashi, Toshinari Kimura, Hisato Igarashi, Takamasa Oono, Masayuki Furukawa, Ken Kawabe, Keiichiro Ogoshi, Jiro Ouchi, Toshihiko Miyahara, Ryoichi Takayanagi, Tetsuhide Ito
World Journal of Gastroenterology , 2008,
Abstract: AIM: To evaluate the efficacy of continuous regional arterial infusion therapy (CRAI) with gabexate mesilate and antibiotics for severe acute pancreatitis (SAP).METHODS: We conducted a prospective study on patients who developed SAP with or without CRAI. Out of 18 patients fulfilled clinical diagnostic criteria for SAP in Japan, 9 patients underwent CRAI, while 9 patients underwent conventional systemic protease inhibitor and antibiotics therapy (non-CRAI). CRAI was initiated within 72 h of the onset of pancreatitis. Gabexate mesilate (2400 mg/d) was continuously administered for 3 to 5 d. The clinical outcome including serum inflammation-related parameters were examined.RESULTS: The duration of abdominal pain in the CRAI group was 1.9 ± 0.26 d, whereas that in the non-CRAI group was 4.3 ± 0.50. The duration of SIRS in the CRAI group was 2.2 ± 0.22 d, whereas that in the non-CRAI group was 3.2 ± 0.28. Abdominal pain and SIRS disappeared significantly in a short period of time after the initiation of CRAI using gabexate mesilate. The average length of hospitalization significantly differed between the CRAI and non-CRAI groups, 53.3 ± 7.9 d and 87.4 ± 13.9 d, respectively. During the first two weeks, levels of serum CRP and the IL6/IL10 ratio in the CRAI group tended to have a rapid decrease compared to those in the non-CRAI group.CONCLUSION: The present results suggest that CRAI using gabexate mesilate was effective against SAP.
Effects of the inhibition of weed communities by winter-flooding  [PDF]
Korehisa Kaneko, Toshihiko Nakamura
Agricultural Sciences (AS) , 2011, DOI: 10.4236/as.2011.24050
Abstract: Winter-flooded paddy field is an agricultural method which putting a water among the winter, it is paid attention as an environmental friendly agriculture. Especially, it is said, winter-flooding is control paddy weeds and there is the farming potential that the annual rice yield is high. However, there is no detailed research about the effects of weed communities by winter-flooding, as the purpose of this study, we investigated the effects of the inhibition of weed communities (life cycle, harmful weed) by winter-flooding at a shore of Inba Lake, Chiba Prefecture, Japan, and compared them to paddy weeds in a dry paddy field. Methods examined the plant height (cm) and the cover degree class of all appearance species in each quadrant frame (1 m2). Quadrant in the two type paddies were 10 frames (D1-D10) at the control, and were 10 frames (W1-W10) at the treatment (Figure 1). In a winter-flooded paddy field, species number and plant volume of winter-annual plants decreased in the third winter after winter-flooding, In particular, the plant volume of Alopecurus aequalis, Cardamine flexuosa decreased significantly. We considered that the cause of this decrease was due to the depth of flooding (more than 10 cm). Eleocharis kuroguwai and Echinochloa oryzoides, which are perennial plants, Sagittaria trifolia, which is an annual plant, increased in a winter-flooded paddy field in the third summer after winter-flooding. We considered that these species grew thicker at places where the seeds germinated, and grew easily, because the conservation situation of the seeds fitted well under the winter-flooding conditions. They started to grow immediately after the drainage of water. The period of drainage coincided with increasing light intensity and temperature. In addition, the annual rice yield of the third year after winter-flooding was higher than that of the habitual practice rice field.
Effect of Ultrasonic Irradiation Conditions on Metal Surface during Multifunction Cavitation  [PDF]
Masataka Ijiri, Toshihiko Yoshimura
Materials Sciences and Applications (MSA) , 2018, DOI: 10.4236/msa.2018.98050
Abstract: Processing using multifunction cavitation (MFC) has recently enabled functional characteristics to be imparted to various materials. It is possible to process a material surface in the same manner as with conventional water jet (WJ) peening; however, the cavitation bubble temperature is different. To further improve this MFC technology, we examine the surface re-forming of low alloy steel (JIS-SCM435) using MFC with various modes of ultrasonic waves. The ultrasonic equipment used for MFC processing includes dual, single, pulse and frequency modulation (FM) ultrasonic modes. Improvement of the residual stress and corrosion resistance was confirmed for all modes. The dual mode showed the maximum values of residual compressive stress and surface potential. The sound pressure at the machining spot was the highest with dual mode, and the temperature in the bubble generated by the WJ nozzle was highest and the amount of dissolved oxygen was lowest. Improvement of the residual stress and corrosion resistance was promoted because the temperature and pressure in the bubble interior during processing was higher than in the other modes.
Dividing Genetic Computation Method for Robust Receding Horizon Control Design
Tohru Kawabe
Applied Computational Intelligence and Soft Computing , 2010, DOI: 10.1155/2010/168653
Abstract: A new robust Receding Horizon Control (RHC) design approach for the sampled-data systems is proposed. The approach is based on a dividing genetic computation of minimax optimization for a robust finite receding horizon control problem. Numerical example is given to show the effectiveness of the proposed method. 1. Introduction In last few decades, the Receding Horizon Control (RHC) has been widely accepted in the industries [1]. RHC is an online powerful control method which solves a control problem with respect to each sampling frequency [2]. A significant merit of RHC is easy handling of constraints during the design and implementation of the controller [2, 3]. In the standard RHC formulation, the current control action is derived by solving a finite or infinite horizon quadratic cost problem at every sample time using the current state of the plant as the initial state [1]. It is an online optimization with big calculation amount. Then, the RHC has been applied conventionally to systems with relatively slow-moving dynamics such as petrochemical plants and so on. However, recent advance of computer performance has made it possible to use it for systems with relatively fast-moving dynamics, for example, the mechatronics and so on. Therefore, it is important to develop a practical RHC method for such systems. Incidentally, a drawback of the standard RHC is explicitly lack of robust property with respect to model uncertainties or disturbances since the online minimized cost function is defined in terms of the nominal systems. A possible strategy for realizing the robust RHC is solving the so-called minimax optimization problem, namely, minimization problem over the control input of the performance measure maximized by plant uncertainties or disturbances. An earliest work was proposed by Campo and Morari [4] and Zheng and Morari [5]. Kothare et al. solve minimax RHC problems with state-space uncertainties through LMIs [6]. Cuzzola et al. improve Kothare's method [6] to reduce conservativeness in [7]. Other methods of minimax RHC for systems with model uncertainty can be found in [8–12]. However, the number of available work of the robust RHC is still limited compared with many methods of robust control synthesis for linear systems being proposed. Main reason of this fact is that the robust (minimax) RHC problem is hard to solve in real-time due to the trade-off with an objective function and constraint conditions in the problem generally. The issue of robust RHC therefore still deserves further attention [2, 3] and the effective approach for the robust
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