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Characteristic of Local Boiling Heat Transfer of Ammonia and Ammonia/Water Binary Mixture on the Plate Type Evaporator

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Journal of Thermal Science 2011年第4期20卷 332-342页

作者： Akio OKAMOTO Hirofumi ARIMA yasuyuki ikegami Titanium Division KOBE STEEL Ltd.Japan Institute of Ocean Energy Saga UniversityJapan

Power generation using small temperature difference such as ocean thermal energy conversion(OTEC)and discharged thermal energy conversion(DTEC)is expected to be the countermeasures against global warming *** ammonia and ammonia/water are used in evaporators for OTEC and DTEC as working fluids,the research of their local boiling heat transfer is important for improvement of the power generation *** of local boiling heat transfer coefficients were performed for ammonia/water mixture(z=0.9-1)on a vertical flat plate heat exchanger in a range of mass flux(7.5-15 kg/m2s),heat flux(15-23 kW/m 2),and pressure(0.7-0.9 MPa).The result shows that in the case of ammonia/water mixture,the local heat transfer coefficients increase with an increase of mass flux and composition of ammonia,and decrease with an increase of heat flux.

关键词： Local Heat Transfer Ammonia/Water Mixture Plate Type Evaporator OTEC

Performance Evaluation of Heat Exchangers in OTEC Using Ammonia/Water Mixture as Working Fluid

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Open Journal of Fluid Dynamics 2013年第4期3卷 302-310页

作者： Takafumi Morisaki yasuyuki ikegami Institute of Ocean Energy Saga University Saga Japan

The ocean thermal energy conversion (OTEC) system is a promising solution to provide stable electricity supply. Although the available temperature difference in OTEC systems is small, an ammonia/water mixture as working fluid is expected to decrease irreversible losses in the heat exchangers and to improve system performance. However, in actual heat exchangers, an adequate temperature crossing does not occur in the condenser but in the evaporator. Therefore, clarification of this characteristic is important. To date, the logarithmic temperature difference (LMTD) method is used in performance evaluations of OTEC heat exchangers. This method is of limited use if physical properties of fluids vary. A generalized mean temperature difference (GMTD) method is introduced to perform this evaluation. As changes in fluid property values can be considered in the GMTD method, method dependencies on heat exchanger characteristics, effectiveness, and system characteristics can be studied. In particular, GMTD and LMTD using a pure substance were found to be almost equal. Mean temperature differences using mixtures as working fluid were higher in the evaporator, but lower in the condenser, from the GMTD method than from the LMTD method. For higher ammonia concentrations in ammonia/water mixtures, the mean temperature differences from both methods are different.

关键词： Ammonia/Water Mixture Evaporation and Condensation Pressure OTEC GMTD LMTD

Experimental and Numerical Investigations on Plate-Type Heat Exchanger Performance

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Open Journal of Fluid Dynamics 2015年第1期5卷 92-98页

作者： yasuyuki ikegami Sami Mutair Yusuke Kawabata Institute of Ocean Energy Saga University Saga Japan

Low-grade Thermal Energy Conversion (LTEC) is a potential source of renewable energy. One of its forms is the Ocean Thermal Energy Conversion (OTEC) in which the temperature difference between the warm surface water and the cold deep water of the ocean is utilized in driving a heat engine cycle. Unlike the conventional thermal power generation systems, the temperature difference between the heat source and heat sink in OTEC system is relatively small. Therefore, efficient heat exchangers should be used since heat exchangers play a major role in the overall system performance and economics. Due to their efficiency even in operating at small temperature difference, plate heat exchangers are strong candidates in OTEC systems. In this study, performance of a herringbone plate-type heat exchanger is experimentally investigated. Moreover, numerical simulation results obtained by using Fluent CFD software are compared with the experimental results and found in good agreement.

关键词： CFD Simulation Nusselt Correlation Plate Heat Exchanger

Dynamic Model for Thermal Energy Conversion Plant Using Small Temperature Difference with Working Fluid of Binary Mixtures

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Dynamic Model for Thermal Energy Conversion Plant Using Smal...

Simple procedure for assessing diffuse subarachnoid hemorrhage successfully created using filament perforation method in mice

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作者： yasuyuki ikegami Masatoshi Nakamura Institute of Ocean Energy Saga UniversityJapan Department of Advanced Systems Control Engineering Graduate School of Science and EngineeringSaga UniversityJapan

＜正＞The thermal energy conversion plant using small temperature difference is a prospective technique for utilizing the ocean thermal energy and waste industrial thermal energy. This paper describes a dynamic model for a kind of this plant based on Uehara cycle built by the Institute of Ocean Energy, Saga University, Japan. Some simulation results attained by this model and the analysis of the results are presented. The analysis can provide useful information for the structure design and control system design of the plant.

关键词： Ocean Thermal Energy Conversion (OTEC) waste-heat utilization dynamic model binary mixtures

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Animal Models and Experimental Medicine 2024年第1期7卷 77-81页

作者： Tatsushi Mutoh Ryota Tochinai Hiroaki Aono Masayoshi Kuwahara yasuyuki Taki Tatsuya Ishikawa Department of Surgical Neurology Research Institute for Brain and Blood VesselsAkita Cerebrospinal and Cardiovascular CenterAkitaJapan Department of Aging Research and Geriatric Medicine Institute of DevelopmentAging and CancerTohoku UniversitySendaiJapan Department of Veterinary Pathophysiology and Animal Health Graduate School of Agriculture and Life SciencesThe University of TokyoTokyoJapan

The murine model of subarachnoid hemorrhage(SAH)is a valuable experimental tool for investigating molecular and cellular mechanisms,and the endovascular filament perforation technique can be used to simulate prominent pathophysiological features observed after human SAH;however,current validation methods for assessing an appropriate SAH model are ***,we introduce a simple procedure for se-lecting a mouse model of diffuse *** was induced in 24 mice using a standard filament perforation *** confirming survival at 24 h,SAH was scored 0-1 based on T2*-weighted images on whole-brain magnetic resonance imaging(MRI)and visual surveillance of the cisterna magna(CM)through the dura *** CM-based SAH grading correlated well with a reference parameter defined by extracted brain(r^(2)=0.53,p<0.0001).The receiver operating characteristic curve revealed a sensi-tivity of 85%and a specificity of 91%for detecting diffuse SAH,with a similar area under the curve(0.89±0.06[standard error of the mean])as the MRI-based grading(0.72±0.10,p=0.12).Our data suggest that confirming an SAH clot in the CM is a valuable way to select a clinically relevant diffuse SAH model that can be used in future experimental studies.

关键词： cisterna magna clot distribution filament perforation mouse model subarachnoid hemorrhage

Initial decrease in the lipoprotein(a)level is a novel prognostic biomarker in patients with acute coronary syndrome

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World Journal of Cardiology 2024年第6期16卷 329-338页

作者： Yasuhiko Saeki Jun Sawaguchi Satori Akita Taka-aki Takamura Kosuke Fujibayashi Minoru Wakasa Hironobu Akao Michihiko Kitayama yasuyuki Kawai Kouji Kajinami Department of Cardiology Kanazawa Medical UniversityUchinada 9200293Japan Trans-catheter Cardiovascular Therapeutics Kanazawa Medical UniversityUchinada 9200293Japan

BACKGROUND Lipoprotein(a)[Lp(a)]is a causal risk factor for atherosclerotic cardiovascular diseases;however,its role in acute coronary syndrome(ACS)remains *** To investigate the hypothesis that the Lp(a)levels are altered by various conditions during the acute phase of ACS,resulting in subsequent cardiovascular *** From September 2009 to May 2016,377 patients with ACS who underwent emergent coronary angiography,and 249 who completed≥1000 d of follow-up were ***(a)levels were measured using an isoform-independent assay at each time point from before percutaneous coronary intervention(PCI)to 48 h after *** primary endpoint was the occurrence of major adverse cardiac events(MACE;cardiac death,other vascular death,ACS,and non-cardiac vascular events).RESULTS The mean circulating Lp(a)level decreased significantly from pre-PCI(0 h)to 12 h after(19.0 mg/dL to 17.8 mg/dL,P<0.001),and then increased significantly up to 48 h after(19.3 mg/dL,P<0.001).The changes from 0 to 12 h[Lp(a)Δ0-12]significantly correlated with the basal levels of creatinine[Spearman’s rank correlation coefficient(SRCC):-0.181,P<0.01]and Lp(a)(SRCC:-0.306,P<0.05).Among the tertiles classified according to Lp(a)Δ0-12,MACE was significantly more frequent in the lowest Lp(a)Δ0-12 group than in the remaining two tertile groups(66.2%vs 53.6%,P=0.034).A multivariate analysis revealed that Lp(a)Δ0-12[hazard ratio(HR):0.96,95%confidence interval(95%CI):0.92-0.99]and basal creatinine(HR:1.13,95%CI:1.05-1.22)were independent determinants of subsequent *** Circulating Lp(a)levels in patients with ACS decreased significantly after emergent PCI,and a greater decrease was independently associated with a worse prognosis.

关键词： Lipoprotein(a) Acute coronary syndrome Percutaneous coronary intervention Major adverse cardiac events Prognosis

Tuning of RF amplitude and phase for the drift tube linac in J-PARC

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Chinese Physics C 2009年第7期33卷 577-582页

作者：沈国保 Masanori ikegami Japan Atomic Energy Agency(JAEA) 2-4 Shirakata-Shirane High Energy Accelerator Research Organization(KEK)

The J-PARC linac has three DTL tanks to accelerate the negative hydrogen ions from 3 MeV to 50 MeV. The RF phase and amplitude are adjusted for each cavity with a phase scan method within the accuracy of 1° in phase and 1% in amplitude. The experimental results show a remarkable agreement with the numerical model within a suffcient margin in the tuning of the last two DTL tanks. However,a notable discrepancy between the experiment and the numerical model is seen in the tuning of the first DTL tank. After studying with a three-dimensional multi-particle simulation,the generation of the low energy component and the pronounced filamentation are identified as the main causes of the discrepancy. The optimization of the tuning scheme is also discussed to attain the tuning goal accuracy for the first DTL tank.

关键词： high-intensity beam drift tube linac signature matching J-PARC

Development of Self-Assembled Supramolecular Catalysts and Their Applications to Organic Synthesis

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复旦学报（自然科学版） 2005年第5期44卷 713-714页

作者： Shiro ikegami School of Pharmaceutical Sciences Teikyo University Sagamiko Kanagawa 199-0195 Japan

In modern synthetic organic chemistry, the development of efficient reagent or catalyst recycling systems is regarded as one of the most important topics. We have previously reported a self-assembled process between poly(N-isopropylacrylamide) (PNIPAAm) based polymer ligands and an inorganic species[1]. This process afforded a networked supramolecular complex where the polymers are cross-linked together by the inorganic species. Thus obtained complex was insoluble in water and worked as an efficient triphase catalyst.

关键词：自组合超分子催化剂有机化学合成方法 PWAA

Design and strategy for manufacturing kidney organoids

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Bio-Design and Manufacturing 2020年第1期3卷 7-14页

作者： Masaki Nishikawa yasuyuki Sakai Norimoto Yanagawa Department of Chemical System Engineering School of EngineeringUniversity of TokyoRm.5A01Engineering Bldg.3Hongo 7‑3‑1BunkyoTokyo 113‑8656Japan Medical and Research Services Greater Los Angeles Veterans Affairs Healthcare System at SepulvedaNorth HillsCAUSA David Geffen School of Medicine University of California at Los AngelesLos AngelesCAUSA

Despite a continuing increase in the number of patients suffering from chronic kidney disease,currently available treatments for these patients,such as dialysis and kidney transplantation,are *** kidney is also a critical target organ vulnerable to the toxicity of various new drugs,and the lack of a reliable in vitro culture model imposes a severe limitation on drug *** the development of induced pluripotent stem cells(iPSCs)revolutionized strategies in biomedical fields,the complexity of the kidney imposed additional challenge to the application of this technology in kidney ***,the recent advancement in our understanding on the developmental origin of kidney progenitor cells and the mechanisms of their reciprocal induction and self-organization has boosted research in kidney *** since then has demonstrated that kidney organoids derived from iPSCs can serve as a useful model for drug discovery and toxicity screening,as well as for disease modeling,especially in combination with gene editing ***,attempts at kidney organoid implantation in animals have suggested their potential as an alternative source of kidney *** this review,we summarize recent progress on the generation of kidney organoids,as well as the obstacles that remain.

关键词： Kidney organoid Kidney development iPSC Progenitor cell Self-organization Regenerative medicine