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高炉内ホールドアップとガス透過率の関係，並びに材料評価から得られる特殊鋼の安定生産に向けた充填層小型化モデルの研究
Get PDF室蘭工業大学Muroran Institute of Technology博士（工学）application/pdf「高炉」や「転炉」は製鉄プロセスの要であり，高炉においては鉄の溶融と還元を同時に処理し，短時間に銑鉄を大量生産できる優れた装置である．しかし高炉で消費されるエネルギーは全プロセスの70%であると言われ，また発生するCO2の発生量も膨大であるなど大きな問題も発生している．一方，特殊合金鋼を生産する転炉でも，回収スクラップによるリサイクル率の大幅なアップや，スラグからの有用成分の効率的な回収など，より複雑なプロセス制御が要求されており，少量高品質化と省エネルギー化を狙ったプロセス革新は，激変する製鉄業界にあって期待度が高い．高炉等の充填粒子内においては，微粒子によるガス流路の閉塞トラブル「bridge(棚吊り)」が最も多く，安定操業に大きな支障を来たしている．充填粒子間の空気の透過性と微粒子による閉塞過程については，従前より充填粒子と微粒子の粒径比が関与する可能性を示唆してきたが，その検証には膨大な実験を必要とした．本研究では，DEM-CFD(粒子－流体連成解析法)による三次元コンピューターシミュレーションを新たに導入し，閉塞の起点と予想されていた「粒径比0.11前後」についてケーススタディを徹底的に検証して，そのメカニズムを明らかにした．また空気流動と微粒子の落下現象がオリフィス部で拮抗する複雑な現象をシンプルな実験装置によりモデル化し，実験と数値シミュレーションが整合することも明らかにした．これより，閉塞の起因を粒子群の複雑な流動化の中から見出したことは大きく，より確度の高いシミュレーション技術を進めることができ，小型炉のプロセス検討に向けて大きな前進に繋がったと言える．一方，転炉では，最近注目度の高い「二相ステンレス鋼(SUS821L1)」の生産プロセスを取り上げ，その溶融段階での改良を最終材料の強度評価から提案する方法を試みた．二相ステンレス鋼は異なる性質の二相が同時に存在するため溶融段階での温度制御は複雑であり，更には一度スラグ化した酸化クロムを回収して再還元化する必要もあって，粒子やガス流の反応制御も難しい．本論文では材料強度の評価実験として準静的から衝撃の範囲までの引張試験を実施し，一例として低温領域(273K～233K)の準静的引張で，マルテンサイト変態による加工硬化挙動が顕著に発生することを捉えた．これより，新素材でもNi当量から材料物性を制御できる可能性を示唆した．以上本論文は溶融炉における粒子挙動や流体の特徴的な流れを把握し，また特殊合金鋼の生産プロセスの処方箋を最終材料の特性から導くなど，前工程のプロセスオペレーションに関して新展開法を提供した功績は大きい．Blast furnaces and "converters" are the key technology of the iron-making process. In blast furnaces, iron is melted and reduced at the same time, and it is an excellent device that can mass-produce pig iron in a short time. However, enormous amount of the energy consumed by the blast furnace about 70% of the total process, and generated CO2 become major problems. Moreover, in the converters for special alloy production, proper control is required due to complicated process and significant increase in the recycling rate of recovered scrap and useful components from slag. Thus, process innovation of energy saving is highly expected in the rapidly changing steel industry. Among the filled particles in a blast furnace, the most serious problem is "bridge", which is blocking the flow channel and hinder the gas permeability due to the fine particles accumulation that disturb the stable operation. From the previous study, the fine to packed bed particle size ratio is related to the start of the blockage. However, a huge amount of experiment was required to verify it. In this study, three-dimensional computer simulation using DEM-CFD (Particle and Fluid Dynamics), already verified the previous study of “particle size ratio around 0.11" as the starting point of occlusion. Moreover, this study also modeled a phenomenon in which air flow and falling particles antagonize at the orifice by using a simple experimental device, where the experiment and numerical simulation are consistent. The blockage mechanism was understood even in the complicated fluidization of the particle swarm, which led to a great progress toward the process study of designing a small furnace. Also, in the converter, this study took up the production process of "duplex stainless steel (SUS821L1)", which increase in demand recently. Duplex stainless steel has two phases with different properties thus required complicated temperature control at the melting stage. Moreover, it is necessary to recover and reduce chromium oxide from the slag, which makes more difficult control. In this study, a tensile test from quasi-static to impact range is carried out as an evaluation of material strength. As an example, work hardening behavior due to martensitic transformation is remarkable in quasi-static tensile in the low temperature region (273K to 233K), which suggests that the material properties may be able to control from Ni equivalents. This paper provided a new development method for the process operation to understand the particle behavior and the gas flow characteristic in the melting furnace, and deriving the method of the production process of special alloy steel from the characteristics of the final material.doctoral thesi
In Vivo Transcutaneous Monitoring of Hemoglobin Derivatives Using a Red-Green-Blue Camera-Based Spectral Imaging Technique
Get PDFapplication/pdfCyanosis is a pathological condition that is characterized by a bluish discoloration of the skin or mucous membranes. It may result from a number of medical conditions, including disorders of the respiratory system and central nervous system, cardiovascular diseases, peripheral vascular diseases, deep vein thrombosis, and regional ischemia. Cyanosis can also be elicited from methemoglobin. Therefore, a simple, rapid, and simultaneous monitoring of changes in oxygenated hemoglobin and deoxygenated hemoglobin is useful for protective strategies against organ ischemic injury. We previously developed a red-green-blue camera-based spectral imaging method for the measurements of melanin concentration, oxygenated hemoglobin concentration (C-HbO), deoxygenated hemoglobin concentration (C-Hb(R)), total hemoglobin concentration (C-HbT) and tissue oxygen saturation (StO(2)) in skin tissues. We leveraged this approach in this study and extended it to the simultaneous quantifications of methemoglobin concentration (C-metHb), C-HbO, C-Hb(R), and StO(2). The aim of the study was to confirm the feasibility of the method to monitor C-metHb, C-HbO, C-Hb(R), C-HbT, and StO(2). We performed in vivo experiments using rat dorsal skin during methemoglobinemia induced by the administration of sodium nitrite (NaNO2) and changing the fraction of inspired oxygen (FiO(2)), including normoxia, hypoxia, and anoxia. Spectral diffuse reflectance images were estimated from an RGB image by the Wiener estimation method. Multiple regression analysis based on Monte Carlo simulations of light transport was used to estimate C-HbO, C-HbR, C-metHb, C-HbT, and StO(2). C-metHb rapidly increased with a half-maximum time of less than 30 min and reached maximal values nearly 60 min after the administration of NaNO2, whereas StO(2) dramatically dropped after the administration of NaNO2, indicating the temporary production of methemoglobin and severe hypoxemia during methemoglobinemia. Time courses of C-HbT and StO(2), while changing the FiO(2), coincided with well-known physiological responses to hyperoxia, normoxia, and hypoxia. The results indicated the potential of this method to evaluate changes in skin hemodynamics due to loss of tissue viability and vitality.journal articl
Transcutaneous monitoring of hemoglobin derivatives during methemoglobinemia in rats using spectral diffuse reflectance
Get PDFapplication/pdfSignificance: Untreated methemoglobinemia may cause severe hypoxemia and even death when methemoglobin levels in the blood stream exceed 70%. Although CO-oximetry can be used to monitor the response to treatment for methemoglobinemia, it is costly and requires an invasive procedure for collecting blood samples from patients. A pulse CO-oximeter with a contact probe can be used to continuously and non-invasively measure the percentage of methemoglobin, as well as the percutaneous oxygen saturation. In terms of the prevention of infectious diseases, however, it is desirable to monitor methemoglobin and oxygen saturation levels in a non-contact manner. Diffuse reflectance spectral imaging is promising as a non-contact, non-invasive, and cost-effective clinical diagnostic tool for methemoglobinemia. Aim: To demonstrate the feasibility of visible spectral diffuse reflectance for in vivo monitoring of hemoglobin derivatives and evaluating methemoglobin production and reduction as well as hypoxemia during methemoglobinemia in rats. Approach: A new imaging approach based on the multiple regression analysis aided by Monte Carlo simulations for light transport was developed to quantify methemoglobin, oxygenated hemoglobin, and deoxygenated hemoglobin using a hyperspectral imaging system. An in vivo experiment with rats exposed to sodium nitrite (NaNO2) at different doses was performed to confirm the feasibility of the method for evaluating the dynamics of methemoglobin, oxygenated hemoglobin, and deoxygenated hemoglobin during methemoglobinemia. Systemic physiological parameters, including the percutaneous arterial oxygen saturation, heart rate (HR), and pulse distention, were measured by a commercially available pulse oximeter, and the results were compared to those obtained by the proposed method. Results: Both the methemoglobin concentration and methemoglobin saturation rapidly increased with a half-maximum time of <20 min. They reached their maximal values nearly 60 min after the administration of NaNO2. Tissue oxygen saturation dramatically dropped to a minimum of 33.7% +/- 0.4%, 23.1% +/- 5.6%, 8.8% +/- 1.7%, and 9.7% +/- 5.1% on average for NaNO2 doses of 25, 37.5, 50, and 75 mg/kg, respectively. Changes in methemoglobin concentration and tissue oxygen saturation are indicative of the temporary production of methemoglobin and severe hypoxemia during methemoglobinemia. Profound increases in the HR and pulse distention implied an elevated cardiac output caused by tachycardia and the resultant increase in peripheral blood volume to compensate for the hypoxia and hypoxemia during methemoglobinemia. This was in agreement with the time course of the peripheral hemoglobin volume concentration obtained by the proposed method. Conclusions: The proposed method is capable of the in vivo non-contact simultaneous evaluation of methemoglobin levels and hypoxemia during methemoglobinemia, and that it has potential as a tool for the diagnosis and management of methemoglobinemia. (C) The Authors. Published by SPIE under a Creative Commons Attribution 4.0 Unported License.journal articl
Reduction of formaldehyde emission from urea-formaldehyde resin with a small quantity of graphene oxide
Get PDFapplication/pdfGraphene oxide (GO) has theoretically been identified as a candidate for adsorbing formaldehyde molecules. However, whether GO can actually serve as a scavenger for formaldehyde resin adhesives must be experimentally verified due to the complex interaction between GO and formaldehyde molecules in the presence of resin, the competition between the formaldehyde emission rate and its adsorption rate on the scavenger, and other complications. From the results from this study we experimentally demonstrate that GO synthesised by the improved Hummers' method is a powerful scavenger for a urea-formaldehyde (UF) resin. We investigate the effect of the added amount of GO on the formaldehyde emission from UF resin. The emission from the UF/GO composite resin is 0.22 +/- 0.03 mg L-1, which is an 81.5% reduction compared to that of the control UF resin when adding 0.20 wt% GO into the UF resin. However, adding higher amounts of GO (more than 0.20 wt%) increases the formaldehyde emission and the emission approaches that of pure UF resin (1.19 +/- 0.36 mg L-1). This is likely due to the more acidic pH of the composite, which may lead to a faster curing reaction of the UF resin and acceleration of the emission.journal articl
Analysis of sweating efficiency and its effects on the heat strain alleviation of clothed subjects
Get PDFapplication/pdfSweating efficiency (SE) is essential for evaluating heat strain. The dripping of sweat off the skin surface of a nude subject occurs locally at an area where the secreted sweat exceeds the local evaporative capacity. However, in clothed subjects, "dripping" sweat is absorbed by clothing. In the present paper, the cooling efficiency of the sweating of a clothed subject is analyzed in relation to SE. First, typical patterns for the regional distribution of the sweat rate (SR) and the capacity of evaporation (CE) of a nude subject were introduced, and the dripping sweat rate was derived as a surplus of the SR over the CE; an equation of SE was derived from combinations of the two typical SR patterns and the uniform CE pattern. Then, the values of SE were calculated numerically, and the results were found to be approximately equal to those obtained experimentally by Alber–Wallerström & Holmér and theoretically from the equation of 1 − 0.5wsw2 used in ISO7933. Based on these results, the SE was improved by arranging the distribution of the CE by controlling air velocities over the body surface. Further, the improved SE was found to contribute to the heat strain alleviation of clothed subjects.journal articl
モード結合理論と機械学習を用いた3次元光導波路デバイスの最適設計の効率化に関する研究
Get PDFapplication/pdf近年，シミュレーション技術の発展により，計算機を用いた光導波路デバイスの自動最適設計が盛んに検討されている．しかしながら，3 次元光導波路デバイスでは，1回の解析の計算コストが高く，最適化過程では更に莫大な計算コストを要する．本研究では，機械学習を用いた光導波路デバイスの最適設計の効率化についての検討を行っている．機械学習に分類されるニューラルネットワークに伝搬解析において計算が必要なパラメータをあらかじめ学習させることで，デバイスの特性評価を効率化し，より効率的な最適設計を行うことができる．本論文では，方向性結合型光デバイスの3次元設計を考え，モード結合理論(CMT)を用いた解析を行う．CMT解析で伝搬ステップごとに計算が必要となる位相不整合量とモード結合係数をニューラルネットワークに学習させることで効率的なデバイス評価を可能にし，進化的手法を用いた効率的な光導波路デバイスの最適設計についての検討を行っているjournal articl
Validation of biphenyl degradation pathway by polymerase chain reaction, peptide mass fingerprinting and enzyme analysis
Get PDFapplication/pdfOur previous studies showed, bacterium Aquamicrobium sp. SK-2 could degrade biphenyl and polychlorinatedbiphenyls (PCBs). In the present study, proteins involved in the biphenyl degradation was evaluatedusing various molecular biology methods. The gene bphC present in the strain SK-2 was identifiedusing the polymerase chain reaction method. Further the key enzyme in biphenyl degradation, 2,3-dihydroxybiphenyl 1,2-dioxygenase (BphC) was purified through anion exchange and gel filtration chromatography,subsequently the enzyme activity was measured. The N-terminal amino acid sequence ofthe purified enzyme showed 92% homology with BphC enzyme of Gram-negative bacteria(Pseudomonas sp. KKS102, Comamonas testosterone, Burkholderiaceae bacterium, Delftia acidovorans, andAchromobacter denitrificans). Fractions collected during protein purification were applied on SDS-PAGEgel. Significant bands were selected in SDS-PAGE gel, and the gel pieces were cut out to analyze the proteinsusing peptide mass fingerprinting (PMF) method. PMF method provided useful information aboutthe proteins involved in biphenyl degradation. Apart from BphC, two other enzymes, benzoate dioxygenaseand catechol 2,3-dioxygenase which were involved in biphenyl degradation process were identified.The results indicate that catechol can be degraded to 2-hydroxymuconic-semialdehyde and this result isin accordance with the results from our previous study. Based on all these results we can conclude thatthe strain SK-2 is a potential candidate for the bioremediation of biphenyl contaminated places._ 2021 The Authors. Production and hosting by Elsevier B.V. on behalf of KeAi Communications Co., Ltd.This is an open access article under the CC BY-NC-ND licensejournal articl
Examining the Hesitation towards Inclusive Education The relationship between the participation of students with developmental disabilities and the sense of order in the classroom climate
Get PDFapplication/pdfInclusive education has become a fundamental policy in the international community. Studies in Europe and the United States have investigated whether both students with special needs and students in the same classrooms improve their academic performance. It was necessary to examine the significance of inclusive education. In Japan, on the other hand, there is a tendency to focus only on the effective implementation of inclusive education. Japan's habitual emphasis on maintaining order may make it hesitant to implement inclusive education. The present study examined the strength of attitudes toward the maintenance of order by gender. Women were also negative toward the maintenance of order. A feminine perspective is essential to the practice of inclusive education.研究報告departmental bulletin pape
A First Report on Academic Exchange Activities in Nepal
Get PDFapplication/pdfMuroran Institute of Technology signed an academic exchange agreement with the Tribhuvan University, Prithvi Narayan Campus (PN Campus) in Nepal in 2018, and is promoting academic exchange activities in both research and exchange cooperation. Prior to the conclusion of the agreement, the author had a personal friendship with faculty members of the PN campus since 2012. They helped local arrangements for fieldwork in Nepal. In concluding an academic exchange agreement in 2018, an undergraduate student and a master student of our Institute have been participating in research workshop at PN campus, moreover, we invited faculty members of PN campus to our university for exchanges. Then, in 2019, students of our university visited the PN campus, and joined a joint workshop to interact with local students. This paper reports on the academic exchange activities between the PN Campus and Muroran Institute of Technology, centering on the implementation report of the joint workshop held in 2019.特集departmental bulletin pape
Current situation of international academic partnership at MuroranIT and proposals for its further development
Get PDFapplication/pdfThis brief report aims not only to understand current situation of international academic partnership at Muroran Institute of Technology (MuroranIT), but also offer some proposals for further development of academic cooperation and exchange with overseas universities and institutes. This report consists of four sections, and its main points are presented in Section 2 and 3. In Section 2, the current status of MuroranIT’s partnership covering its subject, content, type, continent & region, language & culture area, language, term of validity and assessment will be specified. In Section 3, to further develop international academic partnership of MuroranIT, the author makes some proposals in university procedures, strategies, necessity of partnership extensions, acceptance of more international students, grasp of academic cooperation by faculty member and researchers, online international cooperation and reexamination of partnership draft and adoption of legal review process.特集departmental bulletin pape