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Vacancy Dwellings Spatial Distribution—The Determinants and Policy Implications in the City of Sapporo, Japan
Get PDFAs the population is shrinking in many municipalities in Japan, one of its effects is the vacant house crisis. The rise of empty houses profoundly affects the city’s society and economy, e.g., property value reduction, increased crime rate, poor sanitation, and housing market stagnation. To better understand the mechanism of the vacant house crisis, the present study proposes to examine the determinants of housing vacancy spatial distribution with the case study of the city of Sapporo. The results highlight the severe vacant cluster in the central city, which would seem to link to the disequilibrium housing market rather than the urban decline. Regarding vacancy determinants, demographic features were the most influential factors, followed by housing and neighborhood characteristics. Specifically, the vacancy correlated strongly with a high density of single households, children, the elderly (in the center), and a high share of offices. The surplus in housing supply and the inelasticity in housing structures also affected the vacancy significantly. On the contrary, a high percentage of private property, household ownership, and the elderly (in suburban) would reduce the vacancy. For other facilities, clinics, parking, public transportation, and educational institutions had a medium effect on the vacancy. Finally, the influence factors varied, across city areas, in magnitude and direction. These outcomes would be helpful for decision-making to alleviate the rise of vacant houses and their effect on the urban area.journal articl
A study on the change in frost resistance and pore structure of concrete containing blast furnace slag under the carbonation conditions
No full textapplication/pdfIn this study, the change in frost resistance and pore structure of concrete containing blast furnace slag with various replacement ratio due to carbonation were investigated. As a result, there is a close relationship between the carbonation speed and 28-day compressive strength in blast furnace slag concrete. The frost resistance, carbonation resistance and scaling resistance of blast furnace slag cement concrete decrease as blast furnace slag replacement ratio increases. Furthermore, due to carbonation, the frost durability of ordinary Portland cement concrete and the concrete with a low replacement ratio of blast furnace slag tends to decrease. However, the concrete with a high replacement ratio of blast furnace slag tends to increase. Under the carbonation conditions, the pore volume decreases due to carbonation of calcium hydroxide, and the pore structure will be coarsened due to carbonation of C-S-H. In addition, it is expected that permeability of concrete is raised and scaling is inhibited due to carbonation, and the surface area with a certain thickness in the carbonated concrete will be scaled due to freeze-thaw.journal articl
各種促進試験における表面保護材を塗布したモルタルの水分特性と美観変化に関する研究
Get PDF室蘭工業大学Muroran Institute of Technology博士（工学）application/pdfコンクリートの建築物の外側は経年して雨水に含まれたほこり・排気ガスなどの微粒子がコンクリートに付着することが汚れや劣化が発生し，美観や耐久性が問題となる。表面保護材で防汚性を高めるメカニズムには2つあり，親水性と撥水性が挙げられる。親水性は，汚れよりも水との親和性を高めることで水が汚れと塗膜の間に入り込んで，降雨によって汚れを洗い流すという考えである。撥水性は，汚れ自体を付着させにくくさせると言う考えである。また，親水性と撥水性については接触角を図ることで評価することができる。しかし，これまでは表面保護材の効果については耐久性を主眼として評価されており，美装性を評価する上での汚れを防止する要因についての研究は限定されている。そのため，本研究ではシラン系，フッ素樹脂系，ケイ酸塩系の3種類の表面保護材を塗布したコンクリートを対象として，実環境の劣化要因を想定した温水浸漬試験，温冷繰返し試験及び耐候性試験の3つの促進劣化試験を行った後に，表面外観の変化（色差，光沢度，接触角，表面粗さ），透湿試験，吸水性，防汚性試験を測定し，表面保護材を塗布したコンクリートの水分特性と美観変化を評価した。その結果，3つの促進劣化試験後，水に対する浸透抵抗性ではシラン系，フッ素樹脂系およびケイ酸塩系表面保護材に水分浸透抑効果があることが確認された。特に，撥水性を有するシラン系表面保護材でその効果が顕著であった。また美観性については，温水浸漬と耐候性試験後にはシラン系とケイ酸塩系の表面保護材が外観変化しやすく，温水浸漬と温冷繰り返し試験後にはフッ素樹脂系表面保護材で外観変化しやすいことが確認された。フッ素樹脂系表面保護材は，フッ素原子の特性により表面エネルギーが低減し，表面汚染を低減することができることから，温水浸漬後の汚れ抵抗性効果が高いと考えられた。さらに，温冷繰り返し後は撥水性を有するシラン系表面保護材の汚れ抵抗性効果が高く，促進耐候性試験後では紫外線の影響で表面粗さが増加し親水性が高くなるため，シラン系，ケイ酸塩系およびフッ素樹脂系表面保護材の防汚抵抗性に大きな差は認められなかった。以上のように、本研究では各種促進劣化試験前後で、表面保護材の表面粗さと接触角が変化して防汚性能に影響を及ぼすことを明らかするとともに、汚れ面積率を指標とした防汚性の定量評価を行った。Concrete buildings become stained and deteriorate when dust particles, gases and other particles in rainwater adhere to the concrete, causing aesthetic and durability problems. There are two mechanisms by which surface protective materials can improve stain resistance: hydrophilicity and hydrophobic. It based hydrophilicity on increasing the affinity of the coating to water rather than to dirt, water will enter the space between the dirt and the coating, and rainfall will wash the dirt away. Hydrophobic makes it more difficult for the dirt itself to adhere. Hydrophilicity and hydrophobicity can be evaluated by measuring the contact angle. However, until now, the durability of many surfaces protective materials has been estimated, but there has been little research on the factors that prevent staining in the evaluation of aesthetics. Therefore, the aim of this study was therefore to evaluate the moisture properties and aesthetic changes of concrete coated with silane-based, fluor-resin-based, and silicate-based surface protective materials by changes of surface appearance (color difference, gloss, contact angle, roughness), moisture permeability, water absorption and anti-soiling test after warm water immersion aging, humidity, and cool-heat cycling aging and xenon-arc light radiation weathering. After three accelerated degradation tests, we found that silane-based, fluor-resin-based, and silicate-based surface protective materials have been effective in reducing water penetration. In particular, it is silane-based which keeps it hydrophobic. In terms of aesthetics, silane-based and silicate-based are more likely to change in appearance after warm water immersion aging and xenon-arc light radiation weathering. After warm water immersion aging, humidity, and cool-heat cycling aging, the fluor-resin-based were found to be more susceptible to changes in appearance. Fluor-resin-based have a significant anti-soiling effect after warm water immersion aging, which can be attributed to the property of fluorine atoms to reduce the surface energy and reduce surface contamination. After humidity and cool-heat cycling aging, the anti-soiling effect of the silane-based is higher because of its hydrophobic. After xenon-arc light radiation weathering, the anti-soiling resistance of silane-based, fluor-resin-based, and silicate-based have high effect and are almost the same, which because of the increased surface roughness and high hydrophilicity caused by xenon-arc light radiation. In this study, we found that before and after the accelerated weathering, the hydrophobic and hydrophilicity of the surface protective material influenced the anti-soiling performance of the surface protective material as the surface roughness and contact angle changed. In order to quantify the anti-soiling results, the pollution area fraction was subjected to a multiple regression analysis after considering all the test conditions, and it was found that the predicted and experimental results were somewhat correlated.doctoral thesi
先進的仮想化ネットワークのための効率的なマルチリソース割当戦略
Get PDF室蘭工業大学Muroran Institute of Technology博士（工学）application/pdfネットワーク機能の仮想化（ＮＦＶ）ということは、次代のために、仮想化されたネットワーク機能（ＶＮＦ）サービスを提供する新興の方案である。しかし、顧客に異なる資源を配布する効率的な方法を見つけることは難しい。本文の前半は、両面から資源の配分の問題を検討している。まず、DARAという新しいダブルオークションアプローチを開発し、サービス機能チェーン（ＳＦＣ）ルーティングとNFV価格調整の両方に使用され、すべての参加者の利益を最大化することができる。我々の知る限りでは、これはこの分野で初めて採用された策略である。この提案の目的は，NFVブローカー、顧客およびサービスプロバイダという三種類の参加者の利益を最大化することである。次に，ワラシアンオークショングラフィックモデルの樹の多数のノードを提案し，社会的な利益を最大化することができる。仮想化されたサービスをNFV市場で樹評価と定義することは初めてである。そのほか，この手法の正当性を保証するため、アルゴリズムの証明を提出する。すべての理論を考慮して，提案した方法に対して総合のシミュレーションを行った。論文の二番目部分では、深い学習、すなわちサービスとデータ中心の同流スケジュールを含む他のリソースをスケジュールする。第一に、クラウドコンピューティングと深い学習の結合は、最近DLASと呼ばれる新しい技術である。クラウドコンピューティングにおけるプロバイダとユーザの競合市場を設けて，それぞれに二つの効率的な決定と価格戦略を提案する。次に，並列フローの集合であるコーフローをスケジュールする。一つの仕事は一つのコーフローが構成された。共流の依存性を考慮に入れた。完了した性能を保証するために，最後期限とネットワーク容量の制約に基づく「ＭＴＦ」と呼ばれるスケジューラモデルを打ち立ていた。依存コーフローを全体として考慮し，価値的なコーフロースケジューリングの最初のＭＴＦアルゴリズムを提案した。最後に，データセンターにおけるサービスとコーフロースケジューリングとしての深い学習の方法を評価するための広いシミュレーションを行う。Network function virtualization (NFV) is an emerging scheme to provide virtualized network function (VNF) services for next-generation networks. However, finding an efficient way to distribute different resources to customers is difficult. In the first half of this thesis, we deal with the resource allocation from two aspects. First, we develop a new double-auction approach named DARA that is used for both service function chain (SFC) routing and NFV price adjustment to maximize the profits of all participants. To the best of our knowledge, this is the first work to adopt a double-auction strategy in this area. The objective of the proposed approach is to maximize the profits of three types of participants: NFV broker, customers, and service providers. Second, multiple Walrasian Auction Graphic Model of different bundled tree nodes is proposed to maximize the social effectiveness. It is the first work to define the virtualized service as a tree valuation in NFV market. Moreover, we propose the relevant proof of the algorithms to ensure the correctness of the method. With all theory considered, we conducted a comprehensive simulation to evaluate the proposed method. In the second the thesis, we schedule other resources including deep learning as a service and coflow scheduling for datacenter. Firstly, deep learning combining with cloud computing is a surging technology recently which is a new paradigm called DLAS (deep learning as a service). We formulate a competitive market between a provider and users in cloud computing and propose two efficient decision and pricing strategies called Dealer strategies for users and the provider, respectively. Secondly, we schedule coflow which is a collection of parallel flows, while a job consists of a set of coflows. We take the dependency of coflows into consideration. To guarantee job completion for performance, we formulate a deadline and dependency-based model called MTF scheduler model with the constraints of deadline and network capacity. We consider the dependent coflows as an entirety and propose a valuable coflow scheduling first MTF algorithm. Finally, we conduct extensive simulations to evaluate our methods for deep learning as a service and coflow scheduling in datacenter.doctoral thesi
動物繊維からのバイオプラスチックの創製
Get PDF室蘭工業大学Muroran Institute of Technology博士（工学）application/pdfタンパク質を主成分とするシルク、羊毛、クモ糸などの動物繊維を粉砕して得られた粉末を加熱圧縮することで、タンパク質をモノマーとする樹脂が得られる。シルクや羊毛由来の樹脂は、生分解性に加え、既存の石油由来のプラスチックに匹敵する耐熱性や曲げ特性を有している。これまで、樹脂の高機能化を目指し無機材料との複合化や二次加工の導入について検討を行ってきた。本論文では、羊毛樹脂の靭性改善と金属イオン吸着特性について検討を行うとともに、近年注目を集める高強度繊維の人工クモ糸から樹脂の作製を試みることで、石油由来のプラスチックに匹敵する高機能樹脂の創製を目指す。従来の粉末を加熱成形した樹脂は脆性破壊する弱点があった。これを克服すべく、羊毛織布を直接加熱成形することで繊維状組織をもつ樹脂の作製を試みた。羊毛表面のキューティクル層を除去して加熱成形することで、粉末由来の樹脂よりも高い透光性をもつ試料を作製することができた。この樹脂は、応力の負荷により繊維へ戻る可逆性を有するため、耐衝撃性汎用プラスチックに匹敵する優れた衝撃吸収性を示した。次に、動物タンパク質は様々な官能基を有することから、タンパク質樹脂の吸着剤としての利用を検討した。羊毛織布は比表面積が大きく吸着剤に適しているが、吸水率が高く取り扱いが困難である。そこで、羊毛樹脂を吸着剤として模擬廃液から貴金属の回収を試みた。この結果から、羊毛樹脂はAu、Pd、Ptに対し優れた選択性を示すことが確認された。また、織布と比較して比表面積は減少するが、樹脂内部にも金属イオンが拡散することから体積当たりの金属イオン保持量は大きくなった。最後に、新たな動物繊維としてクモ糸を原料に用いて高強度樹脂の作製を試みた。クモ糸は結晶安定性の高いポリアラニン領域が均一に分布するため鋼に匹敵する強度をもつ。また、同タンパク質から成るシルクと比べ結晶性が低く親水性が高い。そこで、可塑剤として水を添加することでさらなる高強度化を図った。結果として、人工クモ糸由来の樹脂は他の動物繊維粉末由来の樹脂と比較し、優れた透光性や曲げ特性を示した。さらに、水を添加することで加熱成形によるポリアラニン領域の結晶化が促進され、樹脂の強度が向上した。本研究では、石油由来のプラスチックにはない機能性をもつタンパク質樹脂を創製することができた。本技術は、繊維廃棄物の資源化を促進し、石油由来のプラスチックの使用量削減に繋がる技術である。今後は、タンパク質樹脂が環境中に流出した際の分解性を評価することで、マイクロプラスチック問題の解決など、より一層持続可能な社会の実現に貢献できると考えている。A resin derived from protein can be obtained by hot-pressing the powder obtained from animal fibers such as silk, wool, and spider silk. These resins have thermal and mechanical properties comparable to petroleum-derived plastics in addition to biodegradability. Our research group has created silk and wool protein resins with high functionality by combining various inorganic materials and introducing the secondary process. In this thesis, we have improved the mechanical strength of wool resin by giving toughness. In the next chapter, we have tried to apply a wool resin as an ion exchange resin to recover noble metals from industrial wastewater. Recently, artificial spider silk attracts our attention because of its excellent mechanical properties. We have introduced this fiber as raw material to fabricate novel protein resin. Resin derived from wool powder exhibits a brittle fracture. We tried to fabricate a resin with a fibrous texture by directly hot-pressing wool fabrics to prevent it. Removal of cuticles on the fiber surface improved wool resin's mechanical strength and translucency. Compared with conventional powder-resin, this resin exhibited a superior impact absorbability, because of its reversibility to the fabric under stress. Next, we evaluated the cation exchange behavior of the protein resin because proteins have various functional groups. Therefore, we tried to recover precious metals from simulated wastewater using wool resin. Our results indicated that Au, Pd, and Pt ions were absorbed selectively on the wool resin. Because the metal ions could be stored in the inner region of resin, the recovery capacity per volume was larger than that of the fabric. Finally, we tried to fabricate a high-performance resin from spider silk. Although spider silk is less crystallinity than silkworm silk composed of the same protein, it has excellent strength due to the dispersion of polyalanine regions which easily forms crystal structure. Moreover, focusing on its hydrophilicity, we tried to improve its strength by adding water as a plasticizer. The artificial spider silk powder-resin had translucency and bending strength superior to the powder-resin derived from other protein fiber. Furthermore, the addition of water promoted the crystallization of the polyalanine region, improving the mechanical properties of the resin. In this study, we have created various protein resins by using low-cost processes. These resins have unique mechanical, biodegradable properties and functions not found in petroleum-derived plastics. In the future, these results could promote the fabric-waste-recycling and reduction of the consumption of petroleum-derived plastics.doctoral thesi
Initial Response of Muroran Institute of Technology to COVID-19 - System Construction for Distance Lectures and Exercises -
Get PDFapplication/pdfFrom March 2020, as a special mission team, we built a system for distance lectures and exercises using E-Learning technology under the disaster caused by COVID-19. In this paper, we reported on outline of the system we build, and shown the issues and current situation unique to our university that hindered our activities in the construction work.特集departmental bulletin pape
厚真川流域の水循環に地震に伴う土地利用・被覆変化が及ぼした影響の評価
Get PDF室蘭工業大学Muroran Institute of Technology博士（工学）application/pdfここ数十年で，土地利用/被覆の変化は地球規模の重大な問題になっている．そして，土地利用/被覆の変化は流域の流出過程に影響するため，水文学の研究においても重要な問題となっている．2018年9月6日に発生した北海道胆振東部地震は最大強度7で，北海道史上最大の地震であった．震災後，厚真川流域では約4,500件の地すべりが発生し，これが近年の厚真川流域の土地利用/被覆変化の主な要因となっている．本研究では，北海道厚真川流域を対象とし，地震前後の土地利用/被覆変化の定量化と分析，および流域流出と土砂流送過程への影響に焦点を当てた．まず，2015年と2020年の厚真川流域の土地利用図を比較分析したところ，主に厚真川流域の上流・中流部の山岳地帯において土地利用・被覆変化が起きていることがわかった．また，地震と地滑りによる土地利用変化を分析すると，約45.9km2の森林面積が20.98km2の裸地と22.75km2の草地に変化したことが分かった．次に，厚真川流域の流出過程を正確にシミュレートするために，土壌および水質評価ツールであるSWATモデルを使用した．流出過程に関する結果として，2015年と2020年の土地利用データを使用して推定された2015-2020年の日次/月次流出シミュレーション結果が類似しており，土地利用/被覆の変化がほとんど影響を与えないことを示している．流域の流出について，2020年の土地利用データを使用して推定された2015-2020年の日次/月次流出シミュレーション結果は，ピーク時の流出過程が2015年の土地利用/被覆データを使用して推定された結果よりもわずかに高いことがわかった．これは，厚真川流域の地震後，森林面積の減少と裸地面積の増加により流出量がわずかに増加したことを示している．最後に土砂流出過程に関する結果より，地震後の月間土砂流送量は以前よりもはるかに多いことがわかった．特に震災後の単位流出あたりの土砂輸送量は，震災前の約4.42倍に増加した．これは，森林面積の減少，裸地面積の増加，河道や山麓周辺に堆積した土砂の影響により，流域の単位流出量あたりの土砂流送量が大幅に増加していることが考えられる．以上のような研究成果は，大きな地震のようなインパクトが流域に起きた場合，水循環や土砂流出の変化によって河川や海域の環境にどのような影響が及ぶのかを推定するうえで役立つと考える．In recent decades, land use/cover change has been a significant global change issue. The impact of land use/cover change on watershed hydrological processes is a research hotspot in hydrology. The Hokkaido Eastern Iburi earthquake occurred on 6 September 2018, with a maximum intensity of 7, was the largest in Hokkaido ever recorded. After the earthquake, about 4,500 landslides occurred in the Atsuma River basin, which are the main factors of land use/cover change in the basin in recent years. This study takes the Atsuma River basin, Hokkaido as the research object. We focus on the quantification and analysis of land use/cover change in the basin before and after the earthquake and its impact on runoff and sediment transport processes. Firstly, by comparing and analyzing the land use maps in 2015 and 2020. We found that the land use/cover change mainly occurred in the mountainous areas in the upper and middle of the basin. The main manifestation is that the earthquake and landslides transformed about 45.9 km2 forest area into 20.98 km2 bare land and 22.75 km2 grassland. Secondly, we used the soil and water assessment tool (SWAT) model to accurately simulate the hydrological processes in the Atsuma River basin. Regarding the runoff process, the simulation results show that the 2015-2020 daily/monthly runoff simulation results estimated using 2015 and 2020 land use data are similar, and the simulation curves are very close, indicating that the land use/cover change has little impact on the watershed runoff. After careful observation, we found that the 2015-2020 daily/monthly runoff simulation results estimated using the 2020 land use data are slightly higher than those estimated using the 2015 land use/cover data in most flow processes, especially at the peak. This indicates that the reduction in forest area and the increase in the bare land slightly increased the runoff after the earthquake in the basin. Regarding the sediment transport process, the simulation results show that the monthly sediment transport after the earthquake is much higher than before. The amount of sediment transported per unit runoff after the earthquake was about 4.42 times before the earthquake, and the change was dramatic. It shows that with the reduction of forest area, the increase of bare land area, and the influence of sediments accumulated around the river channel and foot of the mountain, the amount of sediment transport per unit runoff in the basin has increased significantly. Above research results will be of use to estimate how changes in the hydrologic process and sediment runoff will affect the environment of rivers and seas when a large impact such as a big earthquake occurs in the basin.doctoral thesi
高クロム系多合金白鋳鉄のアブレシブ摩耗特性に関する研究
Get PDF室蘭工業大学Muroran Institute of Technology博士（工学）application/pdf本研究では，産業機械･建機などに幅広く耐摩耗鋼として使用される高クロム系多合金白鋳鉄を対象とし，その耐摩耗性のために添加される微量元素に着目した．BやTiの含有量を調整した高クロム系多合金白鋳鉄を製作し，耐摩耗性への影響を明らかにすることで，耐摩耗性向上に有効な元素とその含有量について検討を行った．第一章では，アブレシブ摩耗に関するこれまでの研究概要について述べるとともに，本研究の意義及び目的を述べた．第二章では，本研究で行った実験方法とその実験方法の有用性について考察した．第三章では，高クロム系多合金白鋳鉄のCr含有率の違いによる耐アブレシブ摩耗特性について検討を行った．まず18Cr系多合金白鋳鉄と27Cr系多合金白鋳鉄を製作し，各供試体が最も高硬度となるよう熱処理を行い，ラバーホイール摩耗試験によるアブレシブ摩耗特性を調査した．その結果，18Cr系多合金白鋳鉄が最も優れた耐アブレシブ摩耗特性を示した．この摩耗特性の有意差は，18Cr系多合金白鋳鉄の方がM7C3炭化物およびM23C6炭化物が基地全体に細かく，均一に晶出しているからだと考えられる．第四章では，高クロム系多合金白鋳鉄のB含有率の違いによる耐アブレシブ摩耗特性について検討を行った．まず18Cr系多合金白鋳鉄と27Cr系多合金白鋳鉄にB含有量を1.5，3.0mass%に変化させた供試材を製作し，各供試体が最も高硬度となるよう熱処理を行った．それらの供試材に対しラバーホイール摩耗試験によるアブレシブ摩耗特性を調査した．その結果，18Cr系，27Cr系多合金白鋳鉄共に，1.5Bが最も優れた耐アブレシブ摩耗特性を示した．一方，硬度測定結果は両供試材ともに1.5B供試材の硬度が最も低い値を示していることから，高クロム系多合金白鋳鉄での耐アブレシブ摩耗特性は硬度，化合物面積率に影響はせず，化合物の晶出形状に影響していると推察される．第五章では，高クロム系多合金白鋳鉄のTi含有率の違いによる耐アブレシブ摩耗特性について検討を行った．まず27Cr系多合金白鋳鉄にTi含有量を1.0，2.0mass%，C含有量を3.0，3.5，4.0mass%に変化させた供試材を製作し，各供試体が最も高硬度となるよう熱処理を行った．それらの供試材に対しラバーホイール摩耗試験によるアブレシブ摩耗特性を調査した．その結果，4C-1Tiが最も優れた耐アブレシブ摩耗特性を示した．よって，高クロム系多合金白鋳鉄にTiを添加することで基地硬さの向上及び炭化物の微細化が行われ，耐アブレシブ摩耗特性の向上に有効である．第六章は総括であり，本研究の成果を要約した．第七章は将来の展望を示しており，鋳造製造過程で使用されるショットブラスト機の投射装置の一部であるブレード材としての活用について展望を示した．In this study, high-chromium multi-alloy white cast iron is widely used in industrial machinery and focuses on its elastic wear properties. By adjusting the amount of added elements to the manufactured multi-alloy white cast iron, the effect on the elastic wear characteristics can be clarified, and the optimum material can be selected. Chapter 1 describes the outline of research on elastic wear so far, and explains the significance and purpose of this research. In Chapter 2, we considered the experimental method used in this study and the usefulness of the experimental method. In Chapter 3, we investigated the abrasive wear resistance characteristics of high-chromium multi-alloy white cast iron due to the difference in Cr content. As a result of experiments on 18Cr-based multi-alloy white cast iron and 27Cr-based multi-alloy white cast iron, 18Cr-based multi-alloy white cast iron had better elastic wear characteristics and tended to correlate with hardness. In Chapter 4, we investigated the abrasive wear resistance characteristics of high-chromium multi-alloy white cast iron due to the difference in B content. Test materials with B content changed to 1.5 and 3.0% were prepared for 18Cr-based multi-alloy white cast iron and 27Cr-based multi-alloy white cast iron, and heat treatment was performed so that each test material had the highest hardness. From the experimental results, the test material in which 1.5% of B was added to 18Cr-based multi-alloy white cast iron showed the best elastic wear characteristics. It was also found that finer carbides crystallized in the metallographic structure exhibit better elastic wear characteristics. In Chapter 5, we investigated the abrasive wear resistance characteristics of high-chromium multi-alloy white cast iron due to the difference in B content. We produced test materials with 27Cr-based multi-alloy white cast iron with Ti content changed to 1.0% and 2.0% and C content changed to 3.0%, 3.5% and 4.0%, and each test material was the highest. Heat treatment was performed to obtain hardness. From the experimental results, the test material in which 1.0% of Ti was added and 4% of C was added to the 27Cr-based multialloy white cast iron showed the best elastic wear characteristics. Therefore, by adding Ti to the high-chromium multi-alloy white cast iron, the substrate hardness is improved and the carbides are miniaturized, which is effective in improving the abrasive wear resistance. Chapter 6 is a summary, but I have summarized the results of this study.doctoral thesi
Turning path tracking control technology for fixed-wing UAV to realize video transmission relay station
Get PDFUnmanned Aerial Vehicles (UAV) are currently used to provide many kinds of services. A video transmission relay station system using fixed-wing UAV that can fly for a long time are now investigated. In the system, the fixed-wing UAV needs to keep turning in the area accurately as a relay station. To realize that we propose a new turning path control system by both switching the roll angle commands to satisfy the balance of both forces and azimuth control to correct the turning radius deviation. The effectiveness was confirmed by computer simulations assuming an actual flight aircraft.journal articl
Physics-informed neural networks for solving the Boltzmann equation of the electron velocity distribution function in weakly ionized plasmas
Get PDFThe equilibrium electron velocity distribution function (EVDF) and electron transport coefficient in weakly ionized plasmas under crossed DC uniform electric and magnetic fields are calculated via the Boltzmann equation (BE) using physics-informed neural networks (PINNs). The latent solution of the BE is represented by an artificial neural network, and then the neural network is trained to respect the BE. By leveraging automatic differentiation, no mesh generation in velocity space is required, allowing us to calculate the three-dimensional EVDF properly with 0.01% of memory capacity required for the conventional mesh-based method. The EVDF and electron transport coefficients in SF6 calculated from the PINNs are benchmarked by comparing with those calculated from the Monte Carlo simulation (MCS). In most cases, the relative difference between the electron transport coefficient calculated from the PINNs and MCS is found to be within 1%.journal articl