京都大学 / 新制・課程博士 / 博士(工学) / 甲第24569号 / 工博第5075号 / 新制||工||1972(附属図書館) / 京都大学大学院工学研究科都市社会工学専攻 / (主査)教授 須崎 純一, 教授 宇野 伸宏, 准教授 松島 格也 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

Ammonia excretion from the freshwater fish gill is thought to occur mainly via passive diffusion of NH3 aided by a favourable plasma-to-water ammonia gradient sustained by a pH gradient formed by an acidified gill boundary layer. Rhesus (Rh) proteins are the newest members of the ammonia transporter superfamily. In this thesis research, ten rainbow trout Rh cDNA sequences were cloned and characterized. Rhcg2 mRNA and H+-ATPase mRNA and activity levels were upregulated in the trout gill pavement cells in response to experimentally elevated plasma ammonia, concurrent with enhanced ammonia excretion. Controversially, Rh proteins are thought to transport C02. However, Rh mRNA levels in most tissues of hypercapnia-exposed trout remained stable suggesting that trout Rh proteins likely do not conduct C02. Xenopus oocytes expressing trout Rh proteins facilitated the bi-directional transport of methylamine, an ammonia analogue. Methylamine transport was inhibited by ammonia and sensitive to a pH gradient and the concentration of the protonated species. Use of the scanning ion electrode technique (SIET) indicated that trout Rh proteins have an ammonia affinity within the physiological range, which is greater than that for methylamine, and they transport ammonia more rapidly than methylamine. A model of ammonia excretion in the trout gill pavement cell is proposed wherein ammonia enters via basolateral Rhbg and exits via apical Rhcg2, binding to these channels as NH4+ but transiting as NH3. In the gill boundary layer, NH3 combines with an H+ ion released from H+-ATPase and/or Na+/H+ exchange, forming NH4+. As low-affinity, high-capacity ammonia transporters, Rh proteins in the trout gill would exploit the favourable pH gradient formed by the acidic boundary layer to facilitate rapid ammonia efflux when plasma ammonia levels are elevated. Basal plasma ammonia levels are likely maintained by simple passive NH3 diffusion with a smaller role for Rh proteins under these conditions. / Thesis / Doctor of Philosophy (PhD)

<p dir="ltr">The roads in the US received a "D" grade on the 2021 report card for America's infrastructure by the American Society of Civil Engineers (ASCE). Poor road conditions generally translate into traffic accidents and vehicle damage, which result in additional expenses for drivers in terms of vehicle repairs and operating costs. To maintain a satisfactory pavement condition over an extended period of time, frequent inspections should be conducted, and any existing and imminent defects should be promptly addressed through corrective and preventive maintenance. However, the current practices are hindered by issues of inspectors' subjectivity, delayed responsiveness, and high costs. This study aims to develop innovative solutions that harness Artificial Intelligence (AI), robotics, and virtual reality (VR) to enhance pavement quality in smart cities.</p><p dir="ltr">The study developed an autonomous system that relies on crowdsourced RGB and depth (RGB-D) data to assess road conditions. A cost-effective data acquisition system that can be mounted on multiple vehicles, was developed. Armed with a substantial dataset of RGB-D pavement surface data, this study explores the effectiveness of various depth-encoding techniques and RGB-D data fusion methods, using pothole detection as a case study. Comprehensive experiments were conducted to evaluate the effectiveness of defect detection using deep convolutional neural networks (DCNN). This study considered all major types of pavement defects in order to comprehensively evaluate pavement conditions. The Pavement Surface Evaluation Rating (PASER) for asphalt pavement is used as a case study. The establishment of an expert system for pavement condition evaluation involves the classification and quantification of pavement data. The system also facilitates the tracking of identified defects and repair work, providing up-to-date information on pavement deterioration and maintenance.</p><p dir="ltr">Another aspect of this study is the improvement of pavement maintenance quality. To enhance the assessment of the effectiveness of pavement maintenance, this study developed immersive VR modules that provide technical staff with a supplementary platform for training. The training materials focus on two common types of pavement maintenance operations: crack sealing and patching. These modules include an interactive decision-making module for evaluating the quality of operations, as well as a hands-on task-performing module for crack sealing machinery preparation and the procedure of full-depth patching. This dissertation has revealed innovative approaches for integrating cutting-edge technologies into the assessment of pavement conditions. The proposed research aims to improve the safety, </p>

<p dir="ltr">Cold mix asphalt (CMA) is an eco-friendly paving material produced at ambient temperatures, offering energy savings by requiring less energy to decrease asphalt binder viscosity. This technology eliminates the need for heating during the mixing and compaction processes, further magnifying its economic benefits when used as a cold-in-place recycling technique. Unlike hot mix asphalts that gain strength through cooling, CMA achieves its final strength through a curing process involving the evaporation of volatiles and the hardening of the emulsified asphalt binder over time. However, its reliance on a curing process for strength development raises concerns about its short-term performance.</p><p dir="ltr">A typical CMA mixture consists of four main components: air voids, mineral aggregate, water, and asphalt droplets suspended in water. The presence of water can significantly influence the overall performance of the mixture under both traffic and environmental loads. Most existing studies on CMA have predominantly focused on the behavior of the mixtures after they have fully cured. However, in real-world scenarios, pavements are often subjected to various stresses during the curing process, which takes up to several months. As a result, premature distress can compromise the early performance of the pavement. Asphalt undergoes significant chemical and physical changes throughout this phase that can influence its final characteristics and in-situ performance. Overlooking this crucial stage can lead to a poor understanding of the material's capabilities and limitations. Despite the importance of this phase, the micromechanical and rheological behaviors of CMA during curing remain largely uncharted territories. Therefore, this dissertation aims to investigate the micromechanical performance of CMA during the curing phase.</p><p dir="ltr">This research study was performed in two study scales: Mastic and Mixture. The first scale focused on the rheological performance of emulsified-cold asphalt mastic (ECAM), considering varying curing levels, different filler-binder ratios, and filler surface treatments. Comprehensive rheological tests, including frequency sweep, temperature sweep, and strain sweep tests, were conducted on fully and partially cured mastic samples, i.e., 20%, 40%, 60%, and 80%, across a wide range of test temperatures. To analyze the physio-chemical adhesion properties between filler and emulsified asphalt, an analytical tool named the “asphalt-filler interaction” theory was formulated to determine the adhesion bond between filler and binder in the presence of moisture. Microscopic images were also captured to analyze the micro-structure and moisture interaction in the CMA’s matrix. Moreover, the presence of moisture in the CMA brings up another complexity during curing time: The water-to-ice phase transition. Normal Force (Nf) was used as a novel measurement parameter to determine water-ice phase transition effects on the rheological study of emulsified mastic. In the mixture scale, mechanical tests were performed on specimens fabricated with two gradations at fully and uncured CMA samples. The mixture experimental tests included the dynamic modulus test, Illinois flexibility index test, Hamburg wheel loaded test, and disc-shaped compact tension test.</p><p dir="ltr">This dissertation presents a thorough analysis and detailed findings that illuminate the complex relationships and behaviors of CMA, particularly at the mastic scale. A significant observation is the direct influence of the filler-to-binder ratio on the curing time; increasing this ratio prolongs the curing process while using a filler with less surface area accelerates it. Notably, 25% of the filler-to-binder ratio enhances the rheological properties of ECAM, particularly at lower loading frequencies. This study further pinpoints the 60% curing level as a crucial threshold in the CMA curing process. Below this, moisture's effect on rheological performance overshadows that of the primary asphalt material, leading to brittle characteristics in freezing conditions and viscous behavior at intermediate temperatures. In the curing stage, the trapped and blocked waters that emerge during the coalescence phase of the emulsified asphalt breaking contribute to the extended curing time of ECAM.</p><p dir="ltr">Additionally, freezing temperatures yield a water-to-ice phase change in uncured ECAM, resulting in a brittle behavior. Interestingly, a direct correlation emerges between curing percentage and freezing point; higher curing percentages relate to lower freezing points. Another significant discovery is the appearance of micropores in fully-cured ECAM, likely due to water evaporation and emulsifier presence, which potentially compromises its performance compared to ECAM fabricated with residual asphalt binder. Furthermore, adjusting the pH, especially by treating limestone filler with hydrochloric acid (HCl), showed noticeable improvements in CMA’s rheological behavior. At the mixture scale, the CMA mixture contained a higher filler-binder ratio in the mixture scale, presenting a better viscoelastic performance and higher cracking resistance at intermediate and freezing temperatures. Moreover, a minimum amount of water, 2.5% by total mass, added to the CMA mixture is essential to ensure adequate mixability, workability, and compactibility. Viscoelastic analysis showed that the curing process changes the transition point from elastic to viscous behavior of CMA mixtures. This shift towards lower frequencies results in a CMA mixture with poor resistance to higher temperature performance.</p>

Polymeric materials are popular in civil infrastructure due to their durability, strength, and resistance to corrosion and environmental degradation. However, the long-term performance of such materials in civil infrastructure is still being researched and investigated. This thesis will focus on the long-term performance of two civil infrastructure applications: 1) high-density polyethylene (HDPE) above-ground storage tanks (AST) and 2) silicone and self-healing polymeric concrete sealants. HDPE is a strong and durable plastic material that is commonly used to store a wide range of liquids ASTs. Currently, there are no established protocols for carrying out non-destructive testing (NDT) and assessment of HDPE ASTs for regular inspections, so this study investigated the viability of using infrared thermography (IRT) and ultrasonic testing (UT) for routine inspection. The study discovered that environmental parameters, such as temperature, wind, and humidity, can affect IRT accuracy, and that a proper heating-cooling cycle can aid in defect detection. Concrete joints in pavement systems are often susceptible to deterioration. They are engineered cracks that enable concrete slabs to expand and contract in response to temperature. They serve the dual purpose of preventing water infiltration and improving ride quality, while extending the pavement's service life. Bridge joints, in particular, are susceptible to water and liquid penetration, which can result in extensive damage over time. By applying sealants to these connections, concrete structures can be protected from such damage, thereby extending their service life. Consequently, a better comprehension of sealant performance and additional research are required to develop effective solutions to address these issues and ensure the safety and longevity of concrete structures prone to cracking. In this study, samples of the two commercial silicone joint sealants were sandwiched between Portland cement mortar specimens and tested using a specially designed fixture to imitate the fatigue performance of the joint under simulated field conditions. The results of the study indicated that the fatigue life of the two silicone sealants were different, with Sealant 2 showed better performance than Sealant 1. Both sealants exhibited adhesive failure initiating debonding along the weak interface of cement mortar cube and joint sealant. The results of commercial sealants are then compared with self-healing polysulfide sealants. This indicates that the performance of sealants can vary, and additional research may be required to develop effective solutions to address these issues. / Master of Science / Polymeric materials are widely utilized in construction due to their durability, strength, and resistance to corrosion and environmental degradation. However, the long-term performance of these materials in civil infrastructure is still under investigation. This thesis specifically examines the long-term performance of two civil infrastructure applications: 1) high-density polyethylene (HDPE) above-ground storage tanks (ASTs) and 2) silicone and self-healing polymeric concrete sealants. HDPE is a robust and durable plastic material commonly employed for storing various liquids in ASTs. Currently, there are no established protocols for conducting non-destructive testing (NDT) and assessment of HDPE ASTs during regular inspections. Therefore, this study investigates the viability of utilizing infrared thermography (IRT) and ultrasonic testing (UT) for routine inspections. The findings reveal that environmental factors such as temperature, wind, and humidity can impact the accuracy of IRT, and implementing a proper heating-cooling cycle can help in detecting such defects inside the tank structure. Concrete joints in pavement systems are susceptible to deterioration. These engineered cracks allow concrete slabs to expand and contract in response to temperature changes, while preventing water infiltration and enhancing ride quality, thus prolonging the pavement's service life. Bridge joints, in particular, are prone to water and liquid penetration, leading to extensive damage over time. Applying sealants to these connections safeguards concrete structures, extending their service life. Consequently, understanding sealant performance and conducting further research are crucial for developing effective solutions to address these issues and ensure the safety and durability of concrete structures prone to cracking. This study involves testing two commercially available silicone joint sealants by sandwiching them between Portland cement mortar specimens. A specially designed fixture is employed to simulate the fatigue performance of joints under field-like conditions. The performance of commercial sealants was also compared with self-healing polysulfide sealants. These findings highlight the variability in sealant performance, emphasizing the need for additional research to develop effective solutions.

När priset på naturtillgångar ökar samt att industrier måste ställa om till en mer hållbar verksamhet innebär detta även en omställning för asfaltsindustrin. Ett sätt för att använda mer återvunnet material i asfaltsindustri är att använda bindemedlet från gammal asfaltsmassa (eng.: reclaimed asphalt pavement, RAP). Detta kan dock inte göras utan komplikationer och därför måste bindemedlet föryngras innan för att kompensera för faktorer så som hög styvhet, låg krakning och trötthetsförmåga samt dålig anti-åldring förmåga hos RAPen. I det här projektet har två olika typer av föryngringsmedel använts; ett växtoljebaserat och ett petroleumbaserat mjukbitumen. Detta för att se om det var möjligt att använda förnybart och återvunnet material i bindemedlet men fortfarande uppnå samma prestanda som konventionellt bindemedel. Två blandningar gjordes hjälp av de två olika föryngringsmedlen och RAPen och analyserades parallellt med ett referensmaterial. Analyserna delades upp i två kategorier: reologi och kemi. Analyserna som föll under reologikategorin var mjukpunkt- och penetrationsanalyser, samt analyser med en dynamisk skjuvning reometer (eng.: dynamic shear rheometer, DSR) och en böjbalksreometer (eng.: bending beam rheometer, BBR). Under kemikategorin fanns analysmetoderna tunnskiktskromatografi med flamjoniseringsdetektor (TLC-FID) och Fourier transform infraröd spektroskopi (FTIR). Resultaten påvisar att åldring påverkas mycket av vilket föryngringsmedel som används, vilket blev tydligt när den reologiska förmågan testades. De kemiska analyserna gav stort sett liknade resultat oberoende av bindemedel. Blandningen som innehöll RAP och mjukbitumen visade sig vara mer mottagligt för åldring jämfört med den andra blandningen som innehöll växtolja, trots att den blandningen innehåller längre halt av RAPen. Vidare visar resultaten att blandningar kan prestera likt referensmaterialet när det kommer till reologi. Från den kemiska aspekten, uppvisar alla bindemedelsmaterial liknande egenskaper. Därför kan slutsatsen att RAPen var återvunnen med framgång när växtolja och mjukbitumen användes. / In recent years there has been a lot of focus on reduction of carbon footprint and sustainable development. For the asphalt industries, a way of doing this is to use reclaimed asphalt pavement (RAP) binders. This cannot be done without any complications and therefore, the RAP binder is normally rejuvenated to compensate for its high stiffness, and other poor properties like susceptibility to low temperature cracking and fatigue damage. In this project, two different ways of using RAP binder are investigated: one vegetable oil-based rejuvenator and one soft bitumen. Using the rejuvenator and soft bitumen together with a RAP binder, two different blends were made and compared to a reference bitumen which is commonly used in Sweden. The blends were made in such a way that the penetration values were close to the reference sample. Aging tests were performed by RTFOT and PAV. The testing of the non-aged and aged binder materials was divided into two sections: rheology and chemistry. The rheology testing included softening point, needle penetration, analysis with dynamic shear rheometer (DSR) and bending beam rheometer (BBR) whereas the chemistry testing included thin layer chromatography with flame ionization detector (TLC-FID) and Fourier transform infrared spectroscopy (FTIR). The results indicated that the ageing resistance of the binder materials is affected by the type of rejuvenator used which especially affects the rheological performance. The chemical performance was almost the same in each blend. The blend containing RAP binder and soft bitumen was more susceptible to ageing compared to the other blend containing oil-based rejuvenator even though the blend contained less of the RAP binder. The results also shows that the blends can perform equal to the reference sample for a rheological point of view. From a chemical point of view, the binders, including the reference, have the same properties. Therefore, the RAP binder was successfully recycled using both a bio-oil rejuvenator and soft bitumen.

In the United States, intersections are among the most frequent locations for crashes. One of the major problems at signalized intersection is the dilemma zone, which is caused by false driver behavior during the yellow interval. This research evaluated driver behavior during the yellow interval at signalized intersections and compared different dilemma zone countermeasures. The study was conducted through four stages. First, the driver behavior during the yellow interval were collected and analyzed. Eight variables, which are related to risky situations, are considered. The impact factors of drivers' stop/go decisions and the presence of the red-light running (RLR) violations were also analyzed. Second, based on the field data, a logistic model, which is a function of speed, distance to the stop line and the lead/follow position of the vehicle, was developed to predict drivers' stop/go decisions. Meanwhile, Cellular Automata (CA) models for the movement at the signalized intersection were developed. In this study, four different simulation scenarios were established, including the typical intersection signal, signal with flashing green phases, the intersection with pavement marking upstream of the approach, and the intersection with a new countermeasure: adding an auxiliary flashing indication next to the pavement marking. When vehicles are approaching the intersection with a speed lower than the speed limit of the intersection approach, the auxiliary flashing yellow indication will begin flashing before the yellow phase. If the vehicle that has not passed the pavement marking before the onset of the auxiliary flashing yellow indication and can see the flashing indication, the driver should choose to stop during the yellow interval. Otherwise, the driver should choose to go at the yellow duration. The CA model was employed to simulate the traffic flow, and the logistic model was applied as the stop/go decision rule. Dilemma situations that lead to rear-end crash risks and potential RLR risks were used to evaluate the different scenarios. According to the simulation results, the mean and standard deviation of the speed of the traffic flow play a significant role in rear-end crash risk situations, where a lower speed and standard deviation could lead to less rear-end risk situations at the same intersection. High difference in speed are more prone to cause rear-end crashes. With Respect to the RLR violations, the RLR risk analysis showed that the mean speed of the leading vehicle has important influence on the RLR risk in the typical intersection simulation scenarios as well as intersections with the flashing green phases' simulation scenario. Moreover, the findings indicated that the flashing green could not effectively reduce the risk probabilities. The pavement marking countermeasure had positive effects on reducing the risk probabilities if a platoon's mean speed was not under the speed used for designing the pavement marking. Otherwise, the risk probabilities for the intersection would not be reduced because of the increase in the RLR rate. The simulation results showed that the scenario with the pavement marking and an auxiliary indication countermeasure, which adds a flashing indication next to the pavement marking, had less risky situations than the other scenarios with the same speed distribution. These findings suggested the effectiveness of the pavement marking and an auxiliary indication countermeasure to reduce both rear-end collisions and RLR violations than other countermeasures.

The U.S. Air Force (USAF) estimates it has a $33 billion (about 10 percent is airfield pavements) deferred maintenance backlog within its $263 billion infrastructure portfolio. Given the scope of this backlog and the importance of airfields, the USAF has a vested interest in finding strategies to help reverse this growing trend. Without an increase in funding, divestiture of excess infrastructure, or change in strategy, this backlog is estimated to climb to over $50 billion by 2030. Reversing the growing infrastructure backlog trend requires new methods and strategies to rethink how the USAF invests in its infrastructure. As such, the overall goal of this research is to develop a comprehensive and practical asset management approach to reduce the total cost of ownership of USAF airfield pavements. By reducing the cost of ownership, the goal is to reverse the growing maintenance backlog while maintaining a pavement portfolio capable of supporting USAF flying operations into the future. While this research is particularly relevant to the USAF, it seeks to fill research gaps within the current body of knowledge related to pavement management strategies for other agency types by presenting a practical, simulation-based methodology for work planning and budget allocation across a large pavement portfolio over a thirty-year period. The dissertation presents the development of the BEAST and RAMPSS algorithms. The BEAST algorithm is a simulation tool capable of modeling behaviors and decisions of 109 organizations managing a global network of airfield pavements over thirty years. Additionally, the BEAST is used to forecast outcomes of USAF investment decisions utilizing its current management strategies and historical behaviors. The RAMPSS is a simulation algorithm designed to select the most economical maintenance strategy for each pavement section in the USAF’s portfolio (i.e., individualized maintenance recommendation strategy for each pavement section). Analysis from the RAMPSS algorithm of the USAF’s pavement portfolio suggests that airfields are generally more cost-effective to maintain if kept in better conditions with strategies other than localized preventative maintenance. The USAF’s current maintenance strategy is unsustainable; however, switching to recommendations from RAMPSS (incorporated and modeled in the BEAST) provides a potentially significant course correction.

No description available.

No description available.