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Investigation of Ant Nest Corrosion on Copper Tube and Estimation of Exchange Current Density on Copper Electrode by Using Differentiating Polarization Method
No full textapplication/pdf家電製品やコンピュータ、車の電子化などエレクトロニクスの著しい発展や熱交換器の高性能化によって銅材料の用途は増加の一途を辿り、銅腐食の形態も多岐に渡っている。エンジンなどの構成材料を強化するために用いられる銅配合合金もバイオマス化による新たな燃焼形態によって腐食モードが異なる場合が見られる。ここでは銅材料の腐食形態で最近深刻な問題を引き起こしている「蟻巣腐食」を実験的に再現し、そのメカニズムについて考察する。また金属腐食に見られる水素発生反応を、より高精度な微分分極法によって解析し燃料電池などの電極開発に指針を与える基礎データを示した。またバイオマス燃料化の一環として液体燃料とメタンガスを併用する「デュアルフューエルモード」を取り上げ、エンジン燃焼試験を実施して燃焼効率などを測定し、これら燃焼形態が材料に及ぼす腐食の可能性について基礎実験を通して考察した。1. 銅管で最近注目される蟻巣腐食（ANC）のメカニズムはまだ明確には解っていない。我々は銅試料をギ酸銅溶液(103 ppm)に20日間浸漬することによる腐食電位とpH値の変化を測定し、表面観察、断面観察、pH測定、電気化学測定を実施した。これより、Disproportionation反応とComproportionation反応がANCメカニズムの解明のために重要な要因となることを示した。更に分極抵抗曲線によって、ANCは腐食速度の大きい高速反応系であることがわかった。2. 銅電極は、水素発生反応（HER）の有望な電極である。電極の触媒性能の計算にはHERの交換電流密度（i0）が用いられるが一般的なターフェル外挿法（TEM）では、勾配の読み取りが不正確であり、且つ電極表面に発生する物理的な抵抗の評価計算にも問題がある。この点を改良した微分分極法（DPM）を用い、0.5 mol dm-3 H2SO4溶液中の銅電極のHERを測定した。この結果DPMではTEMより高い精度を有すること、誤差要因である物理抵抗を合理的に除去できることから、ターフェルスロープ領域を正確に読み取ることができた。3. 本研究ではバイオ燃料(BDF)、並びにメタンガスとCO2の成分比率を人工的に調整したバイオガス（メタン比率40～100%）をDual Fuel(DF)に見立てて燃焼実験を行い熱発生率、燃焼安定度などの燃焼特性を測定した。実験では低トルク(3.5Nm)から高トルク(24.6Nm)の4条件で負荷を変化させ、回転数1800～2600 rpmの5条件で実施した。この結果、低負荷運転時のDFMにおいて正味熱効率は低下し、バイオディーゼル置換率、バイオガスエネルギー率、燃料消費率は増加した。これよりDFモードではメタンの影響を大きく受けること、バイオガス中の二酸化炭素は正味熱効率を上昇させる効果があることが示された。 全条件において燃焼安定度は1.7-4.89 %の間であり、実用化において許容できる値であった。The high increasing application of copper due to its advantages attract the author to do research on copper. In addition, research about dual fuel mode in a diesel engine also discussed as follows:1. Ant nest corrosion (ANC) had been found and observed on the copper tube in the air conditioner. However, the mechanism of ANC is still unclear explained. In order to understand the mechanism and behavior of the ANC, a research investigation of ANC on the copper tube was conducted in terms of the variables of the corrosion potential and pH value in 103 ppm copper formate solution over 20 days. The surface observation, cross-sectional observation, daily pH measurement, and electrochemical measurements were conducted in this research. By using all these results, the author explains the mechanisms of the ANC. It was found that Cannizzaro and Comproportionation reaction critically influenced the ANC mechanism. 2. The copper electrode is still a promising electrode in the hydrogen evolution reaction (HER). The Tafel extrapolation method (TEM) is commonly used for the estimation of the exchange current density (i0) on the HER. However, TEM is still hindered because of some issues, such as the improper reading of Tafel slope and the influence of physical resistant. The differential polarization method (DPM) was introduced in this dissertation as a reliable method to estimate the value of the i0. The research was conducted a measurement of HER on copper electrode in 0.5 mol dm-3 H2SO4 solution. The value of i0 is calculated using both methods; the TEM and the DPM. It found that the DPM is a promising method in the calculation of i0. 3. Biodiesel fuel and biogas fuel as promising alternative energy sources for dual‐fuel mode(DFM) diesel engine attract more researchers. Therefore, The DFM operation of diesel engine using biodiesel fuel from used cooking oil and simulated biogas fuel with different methane contents were conducted and focused on the combustion, rate of heat release, combustion stability, and performance. The observation of diesel engine was conducted by varying the torques and engine speeds. The relation of the results of biodiesel replacement, biogas energy ratio, and brake thermal efficiency with methane content ratio in DFM show that the methane content ratio has the maximum effect in DFM. In addition, the carbon dioxide content in the biogas can enrich the brake thermal efficiency. The combustion stability of all conditions is from 1.7% to 4.89%, which is still acceptable
銅管の蟻巣腐食の調査と微分分極法を用いた銅電極の交換電流密度の推定
Get PDF室蘭工業大学Muroran Institute of Technology博士（工学）application/pdf家電製品やコンピュータ、車の電子化などエレクトロニクスの著しい発展や熱交換器の高性能化によって銅材料の用途は増加の一途を辿り、銅腐食の形態も多岐に渡っている。エンジンなどの構成材料を強化するために用いられる銅配合合金もバイオマス化による新たな燃焼形態によって腐食モードが異なる場合が見られる。ここでは銅材料の腐食形態で最近深刻な問題を引き起こしている「蟻巣腐食」を実験的に再現し、そのメカニズムについて考察する。また金属腐食に見られる水素発生反応を、より高精度な微分分極法によって解析し燃料電池などの電極開発に指針を与える基礎データを示した。またバイオマス燃料化の一環として液体燃料とメタンガスを併用する「デュアルフューエルモード」を取り上げ、エンジン燃焼試験を実施して燃焼効率などを測定し、これら燃焼形態が材料に及ぼす腐食の可能性について基礎実験を通して考察した。1. 銅管で最近注目される蟻巣腐食（ANC）のメカニズムはまだ明確には解っていない。我々は銅試料をギ酸銅溶液(103 ppm)に20日間浸漬することによる腐食電位とpH値の変化を測定し、表面観察、断面観察、pH測定、電気化学測定を実施した。これより、Disproportionation反応とComproportionation反応がANCメカニズムの解明のために重要な要因となることを示した。更に分極抵抗曲線によって、ANCは腐食速度の大きい高速反応系であることがわかった。2. 銅電極は、水素発生反応（HER）の有望な電極である。電極の触媒性能の計算にはHERの交換電流密度（i0）が用いられるが一般的なターフェル外挿法（TEM）では、勾配の読み取りが不正確であり、且つ電極表面に発生する物理的な抵抗の評価計算にも問題がある。この点を改良した微分分極法（DPM）を用い、0.5 mol dm-3 H2SO4溶液中の銅電極のHERを測定した。この結果DPMではTEMより高い精度を有すること、誤差要因である物理抵抗を合理的に除去できることから、ターフェルスロープ領域を正確に読み取ることができた。3. 本研究ではバイオ燃料(BDF)、並びにメタンガスとCO2の成分比率を人工的に調整したバイオガス（メタン比率40～100%）をDual Fuel(DF)に見立てて燃焼実験を行い熱発生率、燃焼安定度などの燃焼特性を測定した。実験では低トルク(3.5Nm)から高トルク(24.6Nm)の4条件で負荷を変化させ、回転数1800～2600 rpmの5条件で実施した。この結果、低負荷運転時のDFMにおいて正味熱効率は低下し、バイオディーゼル置換率、バイオガスエネルギー率、燃料消費率は増加した。これよりDFモードではメタンの影響を大きく受けること、バイオガス中の二酸化炭素は正味熱効率を上昇させる効果があることが示された。 全条件において燃焼安定度は1.7-4.89 %の間であり、実用化において許容できる値であった。The high increasing application of copper due to its advantages attract the author to do research on copper. In addition, research about dual fuel mode in a diesel engine also discussed as follows:1. Ant nest corrosion (ANC) had been found and observed on the copper tube in the air conditioner. However, the mechanism of ANC is still unclear explained. In order to understand the mechanism and behavior of the ANC, a research investigation of ANC on the copper tube was conducted in terms of the variables of the corrosion potential and pH value in 103 ppm copper formate solution over 20 days. The surface observation, cross-sectional observation, daily pH measurement, and electrochemical measurements were conducted in this research. By using all these results, the author explains the mechanisms of the ANC. It was found that Cannizzaro and Comproportionation reaction critically influenced the ANC mechanism. 2. The copper electrode is still a promising electrode in the hydrogen evolution reaction (HER). The Tafel extrapolation method (TEM) is commonly used for the estimation of the exchange current density (i0) on the HER. However, TEM is still hindered because of some issues, such as the improper reading of Tafel slope and the influence of physical resistant. The differential polarization method (DPM) was introduced in this dissertation as a reliable method to estimate the value of the i0. The research was conducted a measurement of HER on copper electrode in 0.5 mol dm-3 H2SO4 solution. The value of i0 is calculated using both methods; the TEM and the DPM. It found that the DPM is a promising method in the calculation of i0. 3. Biodiesel fuel and biogas fuel as promising alternative energy sources for dual‐fuel mode(DFM) diesel engine attract more researchers. Therefore, The DFM operation of diesel engine using biodiesel fuel from used cooking oil and simulated biogas fuel with different methane contents were conducted and focused on the combustion, rate of heat release, combustion stability, and performance. The observation of diesel engine was conducted by varying the torques and engine speeds. The relation of the results of biodiesel replacement, biogas energy ratio, and brake thermal efficiency with methane content ratio in DFM show that the methane content ratio has the maximum effect in DFM. In addition, the carbon dioxide content in the biogas can enrich the brake thermal efficiency. The combustion stability of all conditions is from 1.7% to 4.89%, which is still acceptable.doctoral thesi
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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