Radiative Magnetohydrodynamic Shocks Around Kerr Black Holes

Rohta Takahashi,Masaaki Takahashi 한국물리학회 2006 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.49 No.4

We study radiative magnetohydrodynamic (MHD) shocks in the accretion °ow around a Kerr black hole for both the polar region and the equatorial region. The energy and the angular mo- mentum across the radiative shocks are not conserved and are radiated away. We .rst present the formalisms of the radiative shock solutions in trans-magnetosonic °ows by using the °ux four- vector in the energy-momentum tensor. Automatic searching procedures for solutions giving many solutions for given boundary conditions are also presented. These procedures enable us to search all possible solutions. We next investigate the eects of radiation on the magnetohydrodynamic shocks. We .nd that a toroidal magnetic .eld is generated at the radiative shock as a back-reaction to the radiation even when only poloidal magnetic .eld is considered outside the shock region. The poloidal magnetic .eld is also changed by the radiation at the shocks, and the location of the Alfv¶en point in the downstream region at the radiative shock is altered by radiation eects. Finally, we apply our calculations to the case of a massive black hole in a galactic center by considering radiation mechanisms, such as synchrotron radiation, bremsstrahlung, and gamma-ray radiation, due to decays of pions produced by proton collisions. We show that MHD shock formation can be a possible mechanism for X-ray and gamma-ray radiation. By solving the radiative transfer equation in the Kerr geometry, we calculate apparent images of the radiative shocks formed in the polar region in the vicinity of a black hole. We call such polar emission the black hole \aurora."

Congestion Control of Grouped Virtual Path Networks

Masaaki Omotani,Shinichiro Chaki,Tatsuro Takahashi,Seiichi Nakajima 대한전자공학회 1993 JC-CNSS : Joint Conference on Communications, Netw Vol.6 No.-

TWO-SWITCH BOOST CHOPPER-BASED PFC RECTIFIER FOR ELECTRONIC BALLAST

Nobuo TAKAHASHI,Yoshito KATO,Masaaki OHKITA,Kenzo OKUTSU,Makoto MATSUYAMA,Mutsuo NAKAOKA 전력전자학회 1998 ICPE(ISPE)논문집 Vol.- No.-

This paper presents a two-switch boost chopper with a sinewave current shaping and power factor correction scheme, which is applied for driving electronic ballast using high frequency resonant inverter.<br/> A working principle of the proposed one-converter type electronic ballast with power factor correction and active filtering schemes is described on the bases of the equivalent circuit of each operation mode, together with operation analysis. The steady-state performance evaluations of this electronic ballast are illustrated and discussed in experiment.<br/>

Endoscopic Findings and Treatment of Gastric Neoplasms in Familial Adenomatous Polyposis

Sato Chihiro,Takahashi Kazuya,Sato Hiroki,Naruse Takumi,Nakajima Nao,Takatsuna Masafumi,Mizuno Ken-ichi,Hashimoto Satoru,Takeuchi Manabu,Yokoyama Junji,Kobayashi Masaaki,Terai Shuji 대한위암학회 2022 Journal of gastric cancer Vol.22 No.4

Purpose Gastric neoplasia is a common manifestation of familial adenomatous polyposis (FAP). This study aimed to elucidate the clinical characteristics, endoscopic features including fundic gland polyposis (FGPsis), and treatment outcomes of gastric neoplasms (GNs) in patients with FAP. Materials and Methods A total of 35 patients diagnosed with FAP, including nine patients from four pedigrees who underwent esophagogastroduodenoscopy (EGD), were investigated regarding patient characteristics, GN morphology, and treatment outcomes. Results Twenty-one patients (60.0%) had 38 GNs; 33 (86.8%) and 5 (13.2%) were histologically diagnosed with adenocarcinoma and adenoma, respectively. There were no specific patient characteristics related to GNs. Nodule-type GNs were more prevalent in patients with FGP than without (52.2% vs. 0.0%, P=0.002) in the upper body of the stomach. Conversely, depressed-type GNs were fewer in patients with FGPsis than in those without (13.0% vs. 73.3%, P<0.001). Slightly elevated-type GNs were observed in both groups (34.8% vs. 20.0%, P=0.538). Even within pedigrees, the background gastric mucosa and types of GNs varied. In total, 24 GNs were treated with endoscopic submucosal dissection (ESD) and eight with endoscopic mucosal resection (EMR). EMR was selected for GNs with FGPsis because of the technical difficulty of ESD, resulting in a lower en bloc resection rate (62.5% vs. 100%, P=0.014). Conclusions Our study indicates the necessity of routine EGD surveillance in patients diagnosed with FAP. Notably, the morphology and location of GNs differed between patients with and without FGPsis. Endoscopic treatment and outcomes require more attention in cases of FGPsis. Purpose Gastric neoplasia is a common manifestation of familial adenomatous polyposis (FAP). This study aimed to elucidate the clinical characteristics, endoscopic features including fundic gland polyposis (FGPsis), and treatment outcomes of gastric neoplasms (GNs) in patients with FAP. Materials and Methods A total of 35 patients diagnosed with FAP, including nine patients from four pedigrees who underwent esophagogastroduodenoscopy (EGD), were investigated regarding patient characteristics, GN morphology, and treatment outcomes. Results Twenty-one patients (60.0%) had 38 GNs; 33 (86.8%) and 5 (13.2%) were histologically diagnosed with adenocarcinoma and adenoma, respectively. There were no specific patient characteristics related to GNs. Nodule-type GNs were more prevalent in patients with FGP than without (52.2% vs. 0.0%, P=0.002) in the upper body of the stomach. Conversely, depressed-type GNs were fewer in patients with FGPsis than in those without (13.0% vs. 73.3%, P<0.001). Slightly elevated-type GNs were observed in both groups (34.8% vs. 20.0%, P=0.538). Even within pedigrees, the background gastric mucosa and types of GNs varied. In total, 24 GNs were treated with endoscopic submucosal dissection (ESD) and eight with endoscopic mucosal resection (EMR). EMR was selected for GNs with FGPsis because of the technical difficulty of ESD, resulting in a lower en bloc resection rate (62.5% vs. 100%, P=0.014). Conclusions Our study indicates the necessity of routine EGD surveillance in patients diagnosed with FAP. Notably, the morphology and location of GNs differed between patients with and without FGPsis. Endoscopic treatment and outcomes require more attention in cases of FGPsis.

Effects of the Geometry of Components Attached to the Drain Valve on the Performance of Water Hammer Pumps

Saito, Sumio,Takahashi, Masaaki,Nagata, Yoshimi,Dejima, Keita Korean Society for Fluid machinery 2011 International journal of fluid machinery and syste Vol.4 No.4

Water hammer pumps can effectively use the water hammer phenomenon in long-distance pipeline networks that include pumps and allow fluid transport without drive sources, such as electric motors. The results of experiments that examined the effect of the geometric form of water hammer pumps by considering their major dimensions have been reported. In addition, a paper has also been published analyzing the water hammer phenomenon numerically by using the characteristic curve method for comparison with experimental results. However, these conventional studies have not fully evaluated the pump performance in terms of pump head and flow rate, common measures indicating the performance of pumps. Therefore, as a first stage for the understanding of water hammer pump performance in comparison with the characteristics of typical turbo pumps, the previous paper experimentally examined how the hydrodynamic characteristics were affected by the inner diameter ratio of the drive and lifting pipes, the form of the air chamber, and the angle of the drive pipe. To understand the behavior of the components attached to the valve chamber and the air chamber that affects the performance of water hammer pumps, the previous study also determined the relationship between the water hammer pump performance and temporal changes in valve chamber and air chamber pressures according to the air chamber capacity. For the geometry of components attached to the drain valve, which is another major component of water hammer pumps, this study experimentally examines how the water hammer pump performance is affected by the length of the spring and the angle of the drain pipe.

Endoscopic Findings and Treatment of Gastric Neoplasms in Familial Adenomatous Polyposis

Sato, Chihiro,Takahashi, Kazuya,Sato, Hiroki,Naruse, Takumi,Nakajima, Nao,Takatsuna, Masafumi,Mizuno, Ken-ichi,Hashimoto, Satoru,Takeuchi, Manabu,Yokoyama, Junji,Kobayashi, Masaaki,Terai, Shuji The Korean Gastric Cancer Association 2022 Journal of gastric cancer Vol.22 No.-

Purpose: Gastric neoplasia is a common manifestation of familial adenomatous polyposis (FAP). This study aimed to elucidate the clinical characteristics, endoscopic features including fundic gland polyposis (FGPsis), and treatment outcomes of gastric neoplasms (GNs) in patients with FAP. Materials and Methods: A total of 35 patients diagnosed with FAP, including nine patients from four pedigrees who underwent esophagogastroduodenoscopy (EGD), were investigated regarding patient characteristics, GN morphology, and treatment outcomes. Results: Twenty-one patients (60.0%) had 38 GNs; 33 (86.8%) and 5 (13.2%) were histologically diagnosed with adenocarcinoma and adenoma, respectively. There were no specific patient characteristics related to GNs.Nodule-type GNs were more prevalent in patients with FGP than without (52.2% vs. 0.0%, P=0.002) in the upper body of the stomach. Conversely, depressed-type GNs were fewer in patients with FGPsis than in those without (13.0% vs. 73.3%, P<0.001). Slightly elevated-type GNs were observed in both groups (34.8% vs. 20.0%, P=0.538). Even within pedigrees, the background gastric mucosa and types of GNs varied. In total, 24 GNs were treated with endoscopic submucosal dissection (ESD) and eight with endoscopic mucosal resection (EMR). EMR was selected for GNs with FGPsis because of the technical difficulty of ESD, resulting in a lower en bloc resection rate (62.5% vs. 100%, P=0.014). Conclusions: Our study indicates the necessity of routine EGD surveillance in patients diagnosed with FAP. Notably, the morphology and location of GNs differed between patients with and without FGPsis. Endoscopic treatment and outcomes require more attention in cases of FGPsis.

Effects of the Air Volume in the Air Chamber on the Performance of Water Hammer Pump System

Saito, Sumio,Takahashi, Masaaki,Nagata, Yoshimi Korean Society for Fluid machinery 2011 International journal of fluid machinery and syste Vol.4 No.2

Recently, as global-scale problems, such as global warming and energy depletion, have attracted attention, the importance of future environmental preservation has been emphasized worldwide, and various measures have been proposed and implemented. This study focuses on water hammer pumps that can effectively use the water hammer phenomenon and allow fluid transport without drive sources, such as electric motors. An understanding of operating conditions of water hammer pumps and an evaluation of their basic hydrodynamic characteristics are significant for determining whether they can be widely used as an energy-saving device in the future. However, conventional studies have not described the pump performance in terms of pump head and flow rate, common measures indicating the performance of pumps. As a first stage for the understanding of water hammer pump performance in comparison to the characteristics of typical turbo pumps, the previous study focused on understanding the basic hydrodynamic characteristics of water hammer pumps and experimentally examined how the hydrodynamic characteristics were affected by the inner diameters of the drive and lift pipes and the angle of the drive pipe. This paper suggests the effect of the air volume in the air chamber that affects the hydrodynamic characteristics and operating conditions of the water hammer pump.

Construction of Variable Cutoff Digital Filter Based on a Changeover of Taps

Mariko Kato,Masaaki Ikehara,Shinichi Takahashi 대한전자공학회 1988 JTC-CSCC : Joint Technical Conference on Circuits Vol.- No.-

Effects of the Lift Valve Opening Area on Water Hammer Pump Performance and Flow Behavior in the Valve Chamber

Sumio Saito,Keita Dejima,Masaaki Takahashi,Gaku Hijikata,Takuya Iwamura 한국유체기계학회 2012 International journal of fluid machinery and syste Vol.5 No.3

Water hammer pumps can effectively use the water hammer phenomenon for water pumping. They are capable of providing an effective fluid transport method in regions without a well-developed social infrastructure. The results of experiments examining the effect of the geometric form of water hammer pumps by considering their major dimensions have been reported. However, these conventional studies have not fully evaluated pump performance in terms of pump head and flow rate, common measures of pump performance. The authors have focused on the effects on the pump performance of various geometric form factors in water hammer pumps. The previous study examined how the hydrodynamic characteristics was affected by the inner diameter ratio of the drive and lift pipes and the angle of the drive pipe, basic form factors of water hammer pumps. The previous papers also showed that the behavior of water hammer pump operation could be divided into four characteristic phases. The behavior of temporal changes in valve chamber and air chamber pressures according to the air volume in the air chamber located downstream of the lift valve was also clarified in connection with changes in water hammer pump performance. In addition, the effects on water hammer pump performance of the length of the spring attached to the drain valve and the drain pipe angle, form factors around the drain valve, were examined experimentally. This study focuses on the form of the lift valve, a major component of water hammer pumps, and examines the effects of the size of the lift valve opening area on water hammer pump performance. It also clarifies the behavior of flow in the valve chamber during water hammer pump operation.

Production of Organic Acids and Amino Acids from Fish Meat by Sub-Critical Water Hydrolysis

Yoshida, Hiroyuki,Terashima, Masaaki,Takahashi, Yohei 嶺南大學校 環境問題硏究所 1999 環境硏究 Vol.19 No.1

Fish meat was easily liquefied by hydrolysis under aubcritical conditions without oxidants, and aqueous phase and water-insoluble phase containing oil and fat-like solid were farmed. Lactic acid found in the raw fish meat (about 0.03 g/g-dry meat) was stable up to the reaction temperature 513 K (3.35 MPa). Pyroglutamic acid was produced with a field of 0.095 kg/kg of dry meat by 30 min reaction at 553 K (6.42 MPa). Amino acids such as cystine, alanine, glycine, and leucine were produced in the temperature range 513-623 K with a maximum peak at 543 K. Amounts of crystine, alanine, glycine, and leucine produced in 5 min at 543 K(5.51 MPa) were 0.024, 0.013, 0.009, and 0.004 kg/kg of dry meat, respectively. The oil extracted with hexane contained useful fatty acids such as eicosapentanoic acid (EPA) and docosahexianoic acid (DHA). Thus, subcritical water hydrolysis would be an efficient process for recovering useful substances from organic waste such as fish waste discarded from fish market.