In the friction stir welding (FSW) process, heat and mechanical work are coupled to produce a solid state weld. The process variables are pin tool rotation speed, translational weld speed, and downward plunge force. The strain-temperature history of a metal element at each point on the cross-section of the weld is determined by the process variables plus the individual flow path taken by the particular filament of metal flowing around the tool and ending on that point. The strain-temperature history determines the properties of a metal filament on the weld cross-section. To control the mechanical properties, the strain-temperature history must be carefully controlled. Indirect estimates of the flow paths and the strain-temperature histories of filaments comprising friction stir welds can be made from a model, if the model provides sufficient information. This paper describes experimental marker studies designed to trace the metal flow streamlines as influenced by variations in the process parameters.

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付記する学位プログラム名: 充実した健康長寿社会を築く総合医療開発リーダー育成プログラム / 京都大学 / 新制・課程博士 / 博士(医科学) / 甲第23816号 / 医科博第137号 / 新制||医科||9(附属図書館) / 京都大学大学院医学研究科医科学専攻 / (主査)教授 伊佐 正, 教授 林 康紀, 教授 村井 俊哉 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM

The focus of this thesis will be the exploration of the narrative constructs around the life and work of Michelangelo Merisi da Caravaggio (1571–1610). This exploration will occur through the study of selected exhibitions curated on the Lombard artist from the twentieth- through twenty-first centuries. It will demonstrate how museums have played a significant role in the public’s understanding and perception of Caravaggio. In this thesis, I will argue that exhibitions on Caravaggio have supported and reshaped the general understanding and perception of the artist in crucial ways not done to the same effect in more nuanced academic scholarship. I will also argue that public exhibitions have functioned according to a different set of agendas from those addressed to academia. For example, exhibitions are conceived and function on guiding principles such as alignment with museum mission statements, audience draw and accessibility, educational outcomes, and the visitor experience. This thesis will seek to determine to what measure these principles have affected the framing of content and to clarify how in particular the selective use of Caravaggio’s biography has affected interpretation of his works within a museum context for a viewing public. The restored enthusiasm for Caravaggio in the second-half of the twentieth century also focused on his personal life due to the publication and translation by Walter Friedlaender of Lives written by his seventeenth-century biographers—Giorgio Mancini, Giovanni Baglione, and Giovanni Pietro Bellori—as well as the publication of documents and court records, which highlighted episodes of Caravaggio’s criminality, all impinging on our interpretation of his artistic merits. Although these findings support our understanding of Caravaggio as a complex individual, they also contribute to the sensationalization and romanticization of the artist as the quintessentially bohemian figure. Furthermore, doubtful attributions and disputes over execution dates problematize our understanding of the artist’s oeuvre and have at certain points reinforced a ‘Caravaggio narrative’ of the rebellious, indecorous artist. It is my intention to show how museum exhibitions have contributed to and exploited this narrative and to determine more precisely how and to what extent they have shaped it. With this exploration of Caravaggio’s narrative construction by museum exhibitions of the twentieth- to twenty-first centuries, I aim to approach and reconsider this subject, which has been dealt with heavily in scholarship, under a different lens. In the case of Caravaggio—whose persona and works have been posthumously manipulated, admired, and condemned at the hands of biographers and critics—it is necessary to approach this subject with renewed, unbiased, and objective vigor within a new frame of understanding: the museum exhibition frame. I will use a comparative method, studying three key exhibitions over time, to show how museums have presented the artist’s career development. I pay particular attention to the incorporation of biography and to the impact the inclusion of selected aspects of his Lives have had on the public view of his works. The influential format of Giorgio Vasari’s Lives of the Artists set the structure and codified the model of biographical determinism that would inform Caravaggio’s later biographers in the interpretation of his works; this has persisted through the twentieth- and twenty-first centuries with the application of psychoanalytic approaches to Caravaggio. The first of the three exhibitions I have selected is Longhi’s 1951 Milan exhibition, Mostra del Caravaggio e dei Caravaggeschi, which restored public consciousness of Caravaggio’s innovative and revolutionary style, reinserting him into the artistic canon. My second example will be The Age of Caravaggio, held at the Metropolitan Museum of Art in 1985. The Met exhibition is novel for its focus on Caravaggio’s relationship with his precursors and contemporaries (the organizing committee deliberately excluded works by Caravaggio’s followers) and for its interpretation of works within their historical context. Finally, I will examine Caravaggio: L’ultimo tempo 1606–1610, held first at the Museo di Capodimonte, Naples 2004–2005, then later as Caravaggio: The Final Years, at the National Gallery, London in 2005, which focused on the more enigmatic part of Caravaggio’s late career after his flight from Rome in 1606. The London 2005 exhibition provided new insight into the artist’s stylistic changes in the last years of his life. These three exhibitions will give insight about the perception shifts of the artist that have taken place in the twentieth and twenty-first centuries as a result of scholarly research spurred by museum exhibitions centered around Caravaggio. / Art History

The background for this thesis work emanates from a desire to drive the production of the VBG Truck Equipment factory in Vänersborg a step further to catch up with the Industry 4.0 standards. Discrete Event Simulation (DES) is a widely adopted tool within industries to model real-world systems to improve their processes. The concern of bottlenecks is a vital problem in optimizing and improving the efficiency of production processes. Finding and investigating bottlenecks is one of the primary considerations of all manufacturing industries.The company aims to enhance its logistics by using automation in its processes. This work focusses on the Paint shop part of the VBG factory. Thus, the VBG would like to analyse the methods to reduce the bottlenecks and the waiting time in the Paint shop production process. There were no simulation models available to analyse the existing paint shop pro duction flow; therefore, a Discrete Event Simulation (DES) model of the VBG Paint shop was built to investigate the bottlenecks and improvement methods. In this thesis work, the DES model of the existing Paint shop that uses the Last in First Out (LIFO) method was investigated to find the throughput and lead time for the products. In comparison, a First in First Out (FIFO) method was used to get a balanced production flow, and its effects were studied. The company currently uses two shifts in their Paint shop, so the alternate arrangement of shifts using the same number of operators was analysed. The analysis of three shifts with the same number of operators gave more efficiency than the existing one, and three shifts with an increasing number of operators were also compared. The shift arrangements were compared with both the LIFO and FIFO methods, and FIFO provided more throughput and balanced production flow. The main bottleneck was identified in the forklift transport waiting time, so an alternate layout using a power and free conveyor system was developed. This alternate arrangement reduced the bottlenecks and produced an increased output. The alternate layout was also compared with LIFO and FIFO methods; FIFO was the most efficient one. The shift patterns were also analysed, and the three shifts with a 50 percent increase in staff can reduce the stock build-up during the start of the first shift. As of this study, it was identified that the alternate model with FIFO is the most suitable solution for the company, and in the coming years, they intend to implement that. From the experimental results obtained, DES can be chosen as a method to analyse the problems associated with limiting the capacity of production. The DES modelling can be extended to the other processes in the factory and can be used for improving logistics and inventory management. The company production flow can be further advanced by evaluating the changes that can be implemented in the factory with real-time data.

Many animal species are known for their unparalleled abilities to encode sensory information that supports fast, reliable action in complex environments, but the mechanisms remain often unclear. Through fast ear motions, bats can encode information on target direction into time-frequency Doppler signatures. These species were thought to be evolutionarily tuned to Doppler shifts generated by a prey's wing beat. Self-generated Doppler shifts from the bat's own flight motion were for the most part considered a nuisance that the bats compensate for. My findings indicate that these Doppler-based biosonar systems may be more complicated than previously thought because the animals can actively inject Doppler shifts into their input signals. The work in this dissertation presents a novel nonlinear principle for sensory information encoding in bats. Up to now, sound-direction finding has required either multiple signal frequencies or multiple pressure receivers. Inspired by bat species that add Doppler shifts to their biosonar echoes through fast ear motions, I present a source-direction finding paradigm based on a single frequency and a single pressure receiver. Non-rigid ear motions produce complex Doppler signatures that depend on source direction but are difficult to interpret. To demonstrate that deep learning can solve this problem, I have combined a soft-robotic microphone baffle that mimics a deforming bat ear with a CNN for regression. With this integrated cyber-physical setup, I have able to achieve a direction-finding accuracy of 1 degree based on a single baffle motion. / Doctor of Philosophy / Bats are well-known for their intricate biosonar system that allow the animals to navigate even the most complex natural environments. While the mechanism behind most of these abilities remains unknown, an interesting observation is that some bat species produce fast movements of their ears when actively exploring their surroundings. By moving their pinna, the bats create a time-variant reception characteristic and very little research has been directed at exploring the potential benefits of such behavior so far. One hypothesis is that the speed of the pinna motions modulates the received biosonar echoes with Doppler-shift patterns that could convey sensory information that is useful for navigation. This dissertation intends to explore this hypothetical dynamic sensing mechanism by building a soft-robotic biomimetic receiver to replicate the dynamics of the bat pinna. The experiments with this biomimetic pinna robot demonstrate that the non-rigid ear motions produce Doppler signatures that contain information about the direction of a sound source. However, these patterns are difficult to interpret because of their complexity. By combining the soft-robotic pinna with a convolutional neural network for processing the Doppler signatures in the time-frequency domain, I have been able to accurately estimate the source direction with an error margin of less than one degree. This working system, composed of a soft-robotic biomimetic ear integrated with a deep neural net, demonstrates that the use of Doppler signatures as a source of sensory information is a viable hypothesis for explaining the sensory skills of bats.

Almost all organisms have an endogenously generated and self-sustained time-keeping system that oscillates with a periodicity of about 24 h, namely the circadian clock, that help them adapt to daily environmental changes. Mammalian circadian rhythms are generated and maintained by transcription-translation feedback loops (TTFLs) and include post-translational modifications to help fine-tune the oscillation. Circadian rhythms control a broad range of cellular signaling pathways including those mechanisms involved in cell division and DNA damage response (DDR). We have previously established that the core clock component PERIOD2 (PER2) binds to the tumor suppressor protein p53, a key regulatory checkpoint component that modulates cell cycle progression and the cellular response to genotoxic stress. PER2 binding to p53 modulates p53's stability, cellular localization, and transcriptional activity. As described in Chapter 2, we now identified PER2 as a previously uncharacterized substrate for the ubiquitin E3 ligase mouse double minute 2 homolog (MDM2), an oncoprotein and negative regulator of p53. Our findings showed that the association between PER2 and MDM2 is independent of the presence of p53. In addition, MDM2 targets PER2 for ubiquitylation and degradation in a phosphorylation-independent fashion. Lastly, our studies showed that MDM2 collaborates with β-transducin repeat-containing proteins (β-TrCPs), an E3 ligase that targets PER2 for ubiquitylation in a phosphorylation-dependent manner, to control PER2 degradation and thus the length of circadian period. Because the p53:MDM2 pathway plays a critical role in the cellular response to genotoxic stress, the project described in Chapter 3 is based on the hypothesis that DNA damage caused by radiation shifts the circadian clock phase via the p53:PER2:MDM2 complex. Firstly, we generated Trp53KO (Trp53 gene encodes mouse p53) cell lines in NIH 3T3 Per2:dLuc reporter cells expressing luciferase driven by the Per2 promoter. Phase-response curves (PRCs) for Trp53WT and Trp53KO reporter cells were obtained in response to ionizing radiation (IR) treatments. Results indicated that Trp53 knockout did not affect radiation-induced circadian phase shifts, whereas increased p53 levels induced by transient inhibitor treatments prevented phase shifts when IR was performed at the trough of PER2 abundance. Additional mechanisms were unveiled that kinases ATM (Ataxia Telangiectasia Mutated), ATR (ATM- and Rad3-related) and CHK2 (Checkpoint Kinase 2) regulate radiation-induced phase shifts. Lastly, we found that CLOCK (Circadian Locomotor Output Cycles Kaput) and CRY1 (CRYPTOCHROME 1) were phosphorylated in response to radiation. Taken together, these results indicate that radiation-induced clock phase shifts involve the activity of kinases ATM, ATR and CHK2, and the modification in CLOCK and CRY1. Chapter 4 is a review of current findings about the interaction between circadian rhythms and the cell division cycle regulation pathway. The article highlights a multidisciplinary approach that combines mathematical modeling and experimental data to reveal how p53:PER2:MDM2 acts as a node controlling timely cell cycle progression. In summary, our work provided evidence that MDM2 targets PER2 for ubiquitylation and degradation in a phosphorylation-independent manner, and this influences circadian oscillation. Furthermore, the exploration of p53:PER2:MDM2 association shed light on how radiation-induced DNA damage shifts clock phase. These findings expose a crosstalk mechanism that senses DNA damage and shifts the clock system. / Doctor of Philosophy / Mammals have a time-keeping system that oscillates with a periodicity of about 24 h, namely the circadian clock, that allows physiological and behavioral adaptation to environmental changes. The circadian clock controls and coordinates processes as diverse as sleep/wake cycle, feeding cycle, daily changes in body temperature, blood pressure and hormone secretion. At the cellular level, the circadian clock exists in almost all cells and controls a broad range of cellular signaling pathways including mechanisms involved in cell division and DNA damage response (DDR) pathway. Circadian disruption, for example, by night shift work, results in accumulation of DNA damage in cells and increases risk of cancer. In my thesis, we found that MDM2, a protein that is involved in the DDR signaling pathway and has the potential to cause cancer, controls the degradation of the core clock protein PERIOD2 (PER2), and thus regulates the length of circadian period. Further work exposed the mechanism for how DNA damage shifts the circadian clock. Our findings will have significant impacts on health and biomedical science, especially shedding light on optimizing the time in a day to give chemo- and radiation therapies to cancer patients.

The Cooperative Alleghany Bear Study (CABS) was initiated in 1994 to address concerns over the lack of biological and ecological data for black bear (Ursus americanus) populations in the Alleghany Mountains of western Virginia. I examined home range dynamics of bears during 1994-2002 on 2 study areas that were approximately 160 km apart. I analyzed my data with 3 home range programs (AMA, HRE, and ABODE) and determined the HRE was the least biased and produced the most biologically reasonable home range estimates. I used HRE to generate annual home ranges (fixed-kernel) for 90 bears over 160 bear years; I also generated seasonal home ranges using MCP. Annual and seasonal home ranges of male and female adult bears in the southern study area were larger than that of male and female adult bears in the northern study area, respectively; southern females and northern males had annual home ranges similar in size at the 95% and 75% fixed-kernel contours. In both study areas, most bears did not shift their range when transitioning from spring to summer (North: 63.0%; South: 57.0%) or from summer to fall (North: 67.0%; South: 65.0%), while most bears shifted their seasonal range between spring and fall (North: 67.0%; South: 52.0%). Most female bears in both study areas maintained the same spring and summer home range throughout the duration of the study, while 63% of northern females changed their fall home range and 55% of southern females maintained their fall home range. I found no differences in annual and seasonal home range size among years or among age classes for adult females, but tests for intra-year seasonal difference indicated that fall range was larger than spring and summer in 1997, when western Virginia experienced a poor mast crop. Females with and without COY had similar annual home ranges in either study area. In the north, seasonal home range size did not differ between females with and without COY, while in the south, breeding females (i.e. without COY) had larger spring ranges and smaller fall ranges than females with COY. In both study areas, females with COY had larger fall home ranges than during spring, while seasonal ranges of breeding females did not vary in size during the year. / Master of Science