Academic literature on the topic 'High-vacuum environment'

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Journal articles on the topic "High-vacuum environment"

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Shiina, Takahiro, Takashi Nakamura, and Hiroyuki Oguma. "OS11W0355 Effects of high vacuum environment on high cycle fatigue properties of Ti-6Al-4V alloy." Abstracts of ATEM : International Conference on Advanced Technology in Experimental Mechanics : Asian Conference on Experimental Mechanics 2003.2 (2003): _OS11W0355. http://dx.doi.org/10.1299/jsmeatem.2003.2._os11w0355.

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Sabulsky, D. O., X. Zou, J. Junca, A. Bertoldi, M. Prevedelli, Q. Beaufils, R. Geiger, et al. "Reaching ultra-high vacuum for a large vacuum vessel in an underground environment." E3S Web of Conferences 357 (2022): 05001. http://dx.doi.org/10.1051/e3sconf/202235705001.

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Located far from anthropical disturbances and with low seismic and magnetic background noise profiles, the LSBB facility is the ideal location for a new hybrid detector for the study of space-time strain. The MIGA infrastructure [1], utilizes an array of atom interferometers manipulated by the same beam, the resonant optical field of a 150 m long optical cavity. The infrastructure constitutes a new method for geophysics, for the characterization of spatial and temporal variations of the local gravity, and is a demonstrator for future decihertz gravitational wave observation. Such an infrastructure requires ultra-high vacuum (10−9 mbar) on a size (150 m) and scale (36 m3) not typically seen in underground laboratories other than CERN [2], and especially in underground environments with high humidity (up to 100%) and significant dust contamination (milimetric to micrometric porous rock particles). Here, we detail the status of the MIGA infrastructure and describe the ongoing generation and analysis of the vacuum works - this comes from tests of the prototype vacuum vessel, focusing on heating cycles, residual gas and heating analysis.
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Xie, Ke, Chang Jiang Song, Ke Feng Li, Liang Zhu, and Qi Jie Zhai. "The Magnetic Properties of Fe-6.5wt.%Si Alloy Powders Produced by High Pressure Gas Atomization." Advanced Materials Research 800 (September 2013): 302–7. http://dx.doi.org/10.4028/www.scientific.net/amr.800.302.

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The soft magnetic properties of Fe-6.5wt.%Si alloy powders produced via high pressure gas atomization under different powder sizes, environments (atmospheric and vacuum) and heat-treatment were presented by vibrating sample magnetometer (VSM), respectively. It is found that the soft magnetic properties of powder gradually grow up as the increasing of the powder size under atmospheric and vacuum environments. However, the using of vacuum environment has an optimal capacity to strengthening the properties rather than atmospheric environment. The heat-treatment of 1000°C for 2 hours offers considerable potential for improving the soft magnetic properties of the powders.
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Bai, Yizhou, Jibin Pu, Haixin Wang, Liping Wang, Qunji Xue, and Shuan Liu. "High humidity and high vacuum environment performance of MoS2/Sn composite film." Journal of Alloys and Compounds 800 (September 2019): 107–15. http://dx.doi.org/10.1016/j.jallcom.2019.06.038.

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Engel, Thomas, and Donald Braid. "High‐speed motor for use in an ultrahigh‐vacuum environment." Review of Scientific Instruments 56, no. 8 (August 1985): 1668–69. http://dx.doi.org/10.1063/1.1138123.

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Tenholte, D., S. Kurth, T. Geßner, and W. Dötzel. "A MEMS friction vacuum gauge suitable for high temperature environment." Sensors and Actuators A: Physical 142, no. 1 (March 2008): 166–72. http://dx.doi.org/10.1016/j.sna.2007.05.031.

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Totolin, Vladimir, Marcello Conte, Edurne Berriozábal, Francesco Pagano, Ichiro Minami, Nicole Dörr, Josef Brenner, and Amaya Igartua. "Tribological investigations of ionic liquids in ultra-high vacuum environment." Lubrication Science 26, no. 7-8 (February 15, 2013): 514–24. http://dx.doi.org/10.1002/ls.1224.

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Kim, Wan-Soo, Dong-Jin Lee, and Sun-Kyu Lee. "Nano-Positioning of High-Power Ultrasonic Linear Motor Stage in High-Vacuum Environment." Transactions of the Korean Society of Mechanical Engineers A 34, no. 11 (November 1, 2010): 1613–22. http://dx.doi.org/10.3795/ksme-a.2010.34.11.1613.

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Mishra, Rajat, Himashu Sharma, and Harshit Mishra. "High-speed vacuum air vehicle." Transportation Systems and Technology 4, no. 3 suppl. 1 (November 19, 2018): 328–39. http://dx.doi.org/10.17816/transsyst201843s1328-339.

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Background: There are a number of problems in the prior art, those are topics of research inputs likes ranges of the drag force generated by the vehicle, lift force at high vehicle motion velocities for compensation of the vehicle weight, Aerodynamic aspects of operation of the vehicle, Aim: Stream wise stability of vehicle motion and levitation and breaking of the vehicles and supersonic speed is not achieved in any mode of transportation. But this present invention related to high speed magnetic levitating transportation. More particularly, present invention is related to high speed magnetic levitating transportation using compressed air chamber in the transportation vehicle. Methods: The present invention is more particularly related to high speed vehicle levitated on a vacuum tunnel by using electromagnetic levitation. As this vehicle will move from one place to another in a vacuum environment and this vehicle will levitate above track with the help of electromagnets. Results: The important thing is its motion, which is possible due to reaction force of high pressure air, coming out from compressed air chamber present in vehicle. Conclusion: It can give us the acceleration as per load requirement and it can achieve supersonic speed in few seconds.
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Jin, Chenggang, Yongqi Zhang, Wenbin Ling, Manxing Liu, Peng E, Chunxi Chen, Yunxuan Li, Zhiyong Peng, Yaowen Lu, and Liyi Li. "Vacuum control system for the Space Plasma Environment Research Facility." Journal of Vacuum Science & Technology B 40, no. 3 (May 2022): 034201. http://dx.doi.org/10.1116/6.0001785.

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The Space Plasma Environment Research Facility (SPERF) is a ground simulation user facility for studying the space plasma physical processes. This study presents the design and construction of a vacuum control system for the SPERF to set up an appropriate vacuum environment for plasma experiments, including the terrestrial space and near space vacuum control systems. Based on the requirements of remote automation, distributed control, centralized management, high reliability, expansibility, and safety, the architecture of the vacuum control system has been divided into three levels. Among these, the local level is the most essential part of the control system, which adopts the programmable logical controller (PLC) with Siemens S7-1500 CPU as the core. The PLC supports multiple communication protocols and can accurately control and monitor the actuators in the process of establishing a vacuum environment. Furthermore, it has the ability to communicate and interact with remote upper computers and the central control system through the supervisory control and data acquisition (scada) software developed based on iFix. Based on the architecture of the vacuum control system, the control process for establishing the vacuum environment, including the ultimate vacuum and experimental vacuum, was designed. It is noteworthy that in experimental vacuum acquisition, the injection of working fluid gas is controlled directly by the central control system, considering the different requirements of the terrestrial space and near space systems for the experimental working pressure and flexibility of the experimental vacuum control. The vacuum control system designed in this study provides technical support for the SPERF to perform the plasma experiments successfully. In addition, it offers reference and insights for the design of vacuum control systems in similar large-scale plasma simulation facilities.
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Dissertations / Theses on the topic "High-vacuum environment"

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Gallo, Antonio. "Magnetic field sensors suitable for high temperature and vacuum operations and for remote handling in harsh environment." Doctoral thesis, Università degli studi di Padova, 2011. http://hdl.handle.net/11577/3427514.

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In the context of the alternative technologies for energy production, nuclear fusion is the most promising in order to reduce global dependence on fossil fuels such as oil and coal. Fusion research aims at developing a new energy source in the medium term and it should be engineered in the second half of this century, coming alongside the current technologies. Research on tokamak such as JET and ITER (DEMO in the future), based on the plasma confinement through the use of magnetic fields, is at present the most promising and should provide important results in the coming two decades. In this context magnetic diagnostics are of great importance, providing key information on the confinement of high temperature plasma and allowing an active control on the position and shape of the plasma itself. This work deals with the design, development and production of magnetic sensors, suitable for operation in hostile environments such as the ITER vacuum vessel. These sensors are designed to withstand high temperatures and intense neutron irradiation and have to be installed behind the plasma first wall, in contact to the vessel. These sensors have been built in order to measure magnetic fields having a frequency between 50Hz and 10 kHz. This work is structured as follows: • Chapter 1 provides an overview of the energy problem and describes the theoretical basis of nuclear fusion • Chapter 2 introduces the importance of the magnetic diagnostic in the thermonuclear fusion research and lists the sensors used in existing machines (JET, RFX-mod, JT60), with a focus on the issues related to ITER • Chapter 3 describes the development and construction of a new type of sensor built using the LTCC technology. This chapter lists the tests and the micrographic analysis carried out upon these new sensors • Chapter 4 describes the development and construction of a new sensor formed by a copper wire with fiberglass insulation (called POZh) wound on a metallic reel • Chapter 5 describes the design of the platform necessary to support these sensors (LTCC/POZh) within the ITER vacuum vessel
Nell’ambito delle tecnologie alternative per la produzione di energia la fusione termonucleare controllata appare la più promettente allo scopo di diminuire la dipendenza mondiale dai combustibili fossili quali il petrolio e il carbone. La ricerca sulla fusione mira allo sviluppo di una nuova fonte energetica nel medio termine e dovrebbe trovare ingegnerizzazione nella seconda metà di questo secolo, affiancando le attuali tecnologie. La ricerca sui tokamak quali JET e ITER e il futuro DEMO, basata sul confinamento del plasma attraverso l’utilizzo di campi magnetici, appare allo stato attuale la più promettente e dovrebbe fornire risultati importanti già nei prossimi due decenni. Nell’ambito della fusione termonucleare controllata grande importanza rivestono le diagnostiche magnetiche, che forniscono informazioni fondamentali sullo stato del plasma e permettono un controllo attivo sulla posizione e la forma dello stesso. Questa tesi si occupa dell’ideazione, sviluppo e produzione di due nuove tipologie di sensori magnetici, adatti al funzionamento in ambienti ostili quali l’interno della camera da vuoto (vessel) di ITER. Tali sensori sono stati ideati per resistere ad alte temperature e ad intensi bombardamenti neutronici e dovranno essere installati dietro la prima parete del vessel, a contatto dello stesso. Si tratta di sensori per campi magnetici aventi una frequenza compresa tra 0.001Hz e 10kHz. La tesi è così strutturata: • Il capitolo 1 fornisce una visione di massima sul problema energetico e descrive i rudimenti teorici della fusione nucleare • Il capitolo 2 introduce il problema delle diagnostiche magnetiche elencando i tipi di sensori utilizzati in macchine esistenti (JET, RFX-mod, JT60), con un approfondimento delle problematiche relative ad ITER • Il capitolo 3 descrive lo sviluppo e la produzione di diversi set di sensori costruiti utilizzando la tecnologia LTCC. Tale capitolo elenca i test e le analisi micrografiche effettuate • Il capitolo 4 descrive lo sviluppo e la costruzione di una serie di sensori costruiti mediante la tecnologia del cavo avvolto usando cavi in rame con isolamento in fibra di vetro denominati POZh • Il capitolo 5 descrive il progetto di una struttura necessaria al supporto di tali sensori (LTCC/POZh) all’interno del vessel di ITER
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Baum, Benjamin [Verfasser], Volker [Akademischer Betreuer] Hinrichsen, and René [Akademischer Betreuer] Smeets. "Design and implementation of a test environment to study late-breakdowns in high voltage vacuum circuit breakers / Benjamin Baum ; Volker Hinrichsen, René Smeets." Darmstadt : Universitäts- und Landesbibliothek Darmstadt, 2017. http://d-nb.info/1149252464/34.

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Williams, Tracey Ann. "Effects of beef enhancement with non-meat ingredients, blade tenderization, and vacuum tumbling on quality attributes of four beef cuts stored in a high oxygen environment." Texas A&M University, 2004. http://hdl.handle.net/1969.1/1493.

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The objective of this study was to evaluate the effects of non-meat ingredients, blade tenderization and vacuum-tumbling on the textural, visual and sensory characteristics of steaks from Biceps femoris, Supraspinatus, Triceps brachii long head, and Longissimus dorsi muscles packaged in high oxygen, modified atomosphere (MAP) system. United Department of Agriculture (USDA) Select muscles (n=72) from each cut were obtained from a commercial processor over three processing days. Muscles were aged for five days at 4ºC. Denuded muscles within a processing day were randomly assigned to one of 24 treatments. This study was a 2 x 4 x 3 factorial arrangement where treatments were control, injection (injected or non-injected), blade tenderization (0, 1, or 2 passes) and vacuum-tumbling (0, 5, 10 or 20 minutes). Injected muscles contained up to 10% of a brine containing 1.55% potassium lactate, 0.1% sodium diacetate, 0.3% sodium tripolyphosphate blend and 0.4% salt in the final product. Muscles were vacuumtumbled and blade tenderized sequentially after injection. Steaks from the muscles were stored in a high oxygen (80% O2, 20% CO2) MAP system for 0, 3, 7, 10 and 14 days at 2ºC. Steaks were evaluated for package purge (%), Warner-Bratzler shear force (kg), cook loss (%), cook time (min), pH, CIE L* a* b* color space values and trained color panel scores on each storage day. A trained descriptive attribute sensory panel evaluated steaks on day 1 only. Warner-Bratzler shear force (P<0.01) and trained sensory panel results (P<0.05) showed that the addition of non-meat ingredients improved tenderness in all four muscles. Sensory detectable connective tissue was lower (P<0.01) in injected steaks for all muscles except in Biceps femoris steaks. Injected steaks had higher pH (P<0.01) measurements than non-injected treatments in all muscles except the Triceps brachii long head. Neither blade tenderization nor vacuum-tumbling had consistent effects in all four muscles. Vacuum-tumbled Biceps femoris steaks had lower bitter flavor aromatics (P<0.05). In conclusion, enhancing beef with non-meat ingredients had the greatest impact on the quality attributes of high connective tissue cuts and Longissimus dorsi steaks.
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Qin, Feili. "Metal Oxide Reactions in Complex Environments: High Electric Fields and Pressures above Ultrahigh Vacuum." Thesis, University of North Texas, 2005. https://digital.library.unt.edu/ark:/67531/metadc4843/.

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Metal oxide reactions at metal oxide surfaces or at metal-metal oxide interfaces are of exceptional significance in areas such as catalysis, micro- and nanoelectronics, chemical sensors, and catalysis. Such reactions are frequently complicated by the presence of high electric fields and/or H2O-containing environments. The focus of this research was to understand (1) the iron oxide growth mechanism on Fe(111) at 300 K and 500 K together with the effect of high electric fields on these iron oxide films, and (2) the growth of alumina films on two faces of Ni3Al single crystal and the interaction of the resulting films with water vapor under non-UHV conditions. These studies were conducted with AES, LEED, and STM. XPS was also employed in the second study. Oxidation of Fe(111) at 300 K resulted in the formation of Fe2O3 and Fe3O4. The substrate is uniformly covered with an oxide film with relatively small oxide islands, i.e. 5-15 nm in width. At 500 K, Fe3O4 is the predominant oxide phase formed, and the growth of oxide is not uniform, but occurs as large islands (100 - 300 nm in width) interspersed with patches of uncovered substrate. Under the stress of STM induced high electric fields, dielectric breakdown of the iron oxide films formed at 300 K occurs at a critical bias voltage of 3.8 ± 0.5 V at varying field strengths. No reproducible result was obtained from the high field stress studies of the iron oxide formed at 500 K. Ni3Al(110) and Ni3Al(111) were oxidized at 900 K and 300 K, respectively. Annealing at 1100 K was required to order the alumina films in both cases. The results demonstrate that the structure of the 7 Å alumina films on Ni3Al(110) is k-like, which is in good agreement with the DFT calculations. Al2O3/Ni3Al(111) (γ'-phase) and Al2O3/Ni3Al(110) (κ-phase) films undergo drastic reorganization and reconstruction, and the eventual loss of all long-range order upon exposure to H2O pressure > 10-5 Torr. Al2O3/Ni3Al(110) film is significantly more sensitive to H2O vapor than the Al2O3/Ni3Al(111) film, and this may be due to the incommensurate nature of the oxide/Ni3Al(110) interface. STM measurements indicate that this effect is pressure- rather than exposure- dependent, and that the oxide instability is initiated at the oxide surface, rather than at the oxide/metal interface. The effect is not associated with formation of a surface hydroxide, yet is specific to H2O (similar O2 exposures have no effect).
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Gohardani, Navid. "An Approach Towards Sustainable Building." Doctoral thesis, KTH, Byggnadsteknik, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-140565.

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The motivation for development of energy efficiency and implementation of novel advanced materials applied in buildings can be traced to increasing energy costs in conjunction with an enhanced environmental awareness among people. This doctoral dissertation presents contributions towards sustainable building, where factors such as building technology, energy efficiency in buildings, workers' health issues during construction measures, and certain economic considerations for renovation of buildings have been considered. The research study aims to provide a knowledge base for motivating building owners to renovate buildings based on energy efficiency and improved indoor environment. The initial phase of the research study identifies a detailed description of common drivers, expected in renovation projects by building owners. In the second phase, an information base is identified which may facilitate the bidding processes for decision makers by means of technological, social and economic aspects. The aforementioned information base can also contribute to attentive decisions regarding sustainable renovation and energy saving measures. A strategy was developed within the Renovation Workshop of Riksbyggen, in order to promote energy saving measures concurrent with major renovations in residential buildings. This operational decision support process was applied in a tenant owners' cooperative in Sweden. The objective of this process was to showcase and more importantly to implement energy saving measures, based on knowledge transfer between different parties involved in the renovation project. For the conducted case study, this process was shown to be of great importance when decisions regarding energy saving measures in conjunction with scheduled renovations are being planned. A unique case study was conducted on two of the most commonly used environmental certification programs for buildings in Sweden; Environmental Building (Miljöbyggnad) and GreenBuilding. Following a granted access to a limited database of submitted applications to Sweden Green Building Council, the most common mistakes in these were identified and categorized. This study contributed to further understanding about the level of ability among building consultants, comprehension of environmental certification, and enhancement of the ability to produce high-quality calculations concerning building-related energy usage. In addition, this insight can provide a basis for planning of continuing education of consultants within the field of building technology. For a church building, a study was conducted subsequent to an exchange of an existing electric coil heating system to a hydronic ground source heat pump system. Analyses of the energy demand and energy signature, prior to and after installation were carried out. The replacement of the original heating system with a ground source heat pump system for the church building constitutes a reduced energy consumption level of approximately 66%, at the average outside temperature of -2.30 °C. This study demonstrated that data from a detailed electric bill can be utilized in order to obtain the energy signature of the building and henceforth assess the energy savings. One aspect of the research, examined the decision making process related to sustainable renovation and refurbishment in buildings. The utilized methodology identified three distinct phases in order to instigate an engagement in sustainable renovation, by means of questionnaires and semi-structured interviews. In particular, the attitudes of stakeholders in Sweden, Denmark and Cyprus to sustainable building were studied through three separate case studies. Within the framework of this study, it was identified that building physics and durability are among the most important drivers for energy renovation. The results provided an insight into the renovation process in the aforementioned countries and identified that drivers such as improvement of indoor air quality and elimination of moisture in the building envelope are also of crucial importance. Another aspect of the conducted research highlights workplace accidents occurring within the Swedish construction sector. The purpose of this study was to serve as a useful tool to track the working environments of construction workers in order to reduce health and safety issues within the construction sector. The findings of this research suggest that despite laws, regulations or additional factors that seek to ensure a safe and healthy environment for construction workers, the Swedish construction work force still faces challenges. Moreover, it is identified that construction workers participating in the study call for additional measures to ensure occupational health and safety. Improved knowledge of economic performance and technical results of renovations can contribute to a snowball effect, with more property owners recognizing the value of energy aspects and thus provide an increased level of energy savings.

QC 20140127


A Concept for promotion of sustainable retrofitting and renovation in Early Stages (ACES)
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Gockel, Brian Timothy. "Developing the capability to examine environmental effects on small fatigue crack growth." Dayton, Ohio : University of Dayton, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1271184488.

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Thesis (M.S. in Mechanical Engineering) -- University of Dayton.
Title from PDF t.p. (viewed 06/22/10). Advisor: Robert Brockman. Includes bibliographical references (p. 42-44). Available online via the OhioLINK ETD Center.
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Lin, Tien-Chih 1966. "Interactions of Clean and Sulfur-modified Reactive Metal Surfaces with Aqueous Vapor and Liquid Environments : A Combined Ultra-high Vacuum/electrochemistry Study." Thesis, University of North Texas, 1998. https://digital.library.unt.edu/ark:/67531/metadc278914/.

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The focus of this research is to explore the molecular-level interactions between reactive metal surfaces and aqueous environments by combined ultra-high vacuum/electrochemistry (UHV-EC) methodology. The objectives of this work are to understand (1) the effects of sulfate ions on the passivity of metal oxide/hydroxide surface layer, (2) the effects of sulfur-modification on the evolution of metal oxide/hydroxide surface layer, and (3) the effects of sulfur adsorbate on cation adsorption at metal surfaces.
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Hales, Matthew Cameron. "Synthesis and characterisation of titanium sol-gels in varied gravity environments." Thesis, Queensland University of Technology, 2012. https://eprints.qut.edu.au/61605/1/Matthew_Hales_Thesis.pdf.

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Sol-gel synthesis in varied gravity is only a relatively new topic in the literature and further investigation is required to explore its full potential as a method to synthesise novel materials. Although trialled for systems such as silica, the specific application of varied gravity synthesis to other sol-gel systems such as titanium has not previously been undertaken. Current literature methods for the synthesis of sol-gel material in reduced gravity could not be applied to titanium sol-gel processing, thus a new strategy had to be developed in this study. To successfully conduct experiments in varied gravity a refined titanium sol-gel chemical precursor had to be developed which allowed the single solution precursor to remain un-reactive at temperatures up to 50oC and only begin to react when exposed to a pressure decrease from a vacuum. Due to the new nature of this precursor, a thorough characterisation of the reaction precursors was subsequently undertaken with the use of techniques such as Nuclear Magnetic Resonance, Infra-red and UV-Vis spectroscopy in order to achieve sufficient understanding of precursor chemistry and kinetic stability. This understanding was then used to propose gelation reaction mechanisms under varied gravity conditions. Two unique reactor systems were designed and built with the specific purpose to allow the effects of varied gravity (high, normal, reduced) during synthesis of titanium sol-gels to be studied. The first system was a centrifuge capable of providing high gravity environments of up to 70 g’s for extended periods, whilst applying a 100 mbar vacuum and a temperature of 40-50oC to the reaction chambers. The second system to be used in the QUT Microgravity Drop Tower Facility was also required to provide the same thermal and vacuum conditions used in the centrifuge, but had to operate autonomously during free fall. Through the use of post synthesis characterisation techniques such as Raman Spectroscopy, X-Ray diffraction (XRD) and N2 adsorption, it was found that increased gravity levels during synthesis, had the greatest effect on the final products. Samples produced in reduced and normal gravity appeared to form amorphous gels containing very small particles with moderate surface areas. Whereas crystalline anatase (TiO2), was found to form in samples synthesised above 5 g with significant increases in crystallinity, particle size and surface area observed when samples were produced at gravity levels up to 70 g. It is proposed that for samples produced in higher gravity, an increased concentration gradient of water is forms at the bottom of the reacting film due to forced convection. The particles formed in higher gravity diffuse downward towards this excess of water, which favours the condensation reaction of remaining sol gel precursors with the particles promoting increased particle growth. Due to the removal of downward convection in reduced gravity, particle growth due to condensation reaction processes are physically hindered hydrolysis reactions favoured instead. Another significant finding from this work was that anatase could be produced at relatively low temperatures of 40-50oC instead of the conventional method of calcination above 450oC solely through sol-gel synthesis at higher gravity levels. It is hoped that the outcomes of this research will lead to an increased understanding of the effects of gravity on chemical synthesis of titanium sol-gel, potentially leading to the development of improved products suitable for diverse applications such as semiconductor or catalyst materials as well as significantly reducing production and energy costs through manufacturing these materials at significantly lower temperatures.
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Baum, Benjamin. "Design and implementation of a test environment to study late-breakdowns in high voltage vacuum circuit breakers." Phd thesis, 2017. https://tuprints.ulb.tu-darmstadt.de/6990/13/Dissertation_Baum.pdf.

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In the last decades, the vacuum switching technology has established itself as the standard in the medium voltage level (Us <= 52kV). However, at higher voltages, this technology is not yet competitive to the current SF6 switching technology. Especially during switching of capacitive loads, a high number of restrikes (dielectric breakdowns) occur. This capacitive switching duty is dielectrically the most challenging for a vacuum circuit breaker and tested widely. However, the interpretation of these tests are difficult due to the absence of suitable diagnostic tools. Therefore, the present thesis deals with the development of a suitable test environment to investigate 72.5 kV vacuum circuit breakers. Based on experiences from the medium voltage level and established research findings in the field of restrikes two main requirements have been derived: 1. The synthetic test circuit needs to be realized using only test transformers. This is necessary to achieve a high number of test series because the use of power transformers is limited and not economical. In case of a capacitive switching duty, this limitation effects the generation of the recovery voltage and how it is applied to the test object. The recovery voltage itself consists in equal parts of a direct and alternating voltage component and must be applied precisely during its voltage zero crossing. This has been realized using two independent voltage sources and a voltage-making switch that has been specially designed for this purpose. 2. A simultaneous detection of field-emission currents and charged micro-particles is needed. Both phenomena can cause restrikes but are not necessarily independent from each other. To measure field-emission currents, a proven concept from the medium voltage level has been adapted towards a high number of capacitive switching operations in rapid succession. This has been achieved by exploiting the separate generation of current and voltage of a synthetic test circuit. Based on their identical interaction with the test circuit, micro-particles have been detected using partial discharge measurement equipment. As a consequence, the whole test environment must have a low partial discharge level to enable this detection. Within this work, the measurement systems as well as the test circuit have been commissioned and tested. It was possible to demonstrate the simultaneous detection of micro-particles and field-emission currents (>= 100 μA). Furthermore, a best practice has been defined for future investigations. Based on first measurements, micro-particle activity up to a second after a switching operation could be observed. In addition, it has been shown, that the recovery voltage can be applied to the test object precisely (+-100 μs) at the voltage zero crossing with an additional voltage-making switch. Thus, the main negative aspect in their generation, which arise from the use of test transformers, can be compensated.
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Ndou, Nthomeni Dorah. "Registered nurses' experiences of working in a high-risk environment for contracting HIV/AIDS." Diss., 2005. http://hdl.handle.net/10500/2112.

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Registered nurses are exposed to the risk of Human Immunodeficiency Virus (HIV) infection and contracting the Acquired Immunodeficiency Syndrome (AIDS). Qualitative phenomenological research was conducted to explore registered nurses' experiences of working in such a high-risk environment and how their experiences influence the therapeutic relationship. A sample of registered nurses who care for HIV-infected persons or persons who suffer from AIDS was purposefully selected. Focus group interviews were conducted. Qualitative data analysis was performed. Frankl's theory of meaning of life served as a theoretical foundation for interpreting the research findings. The research results revealed that registered nurses experience existential frustration due to the intentional and unintentional risks that they are exposed to. This negatively impacts upon their ability to maintain a healthy therapeutic relationship with patients. However, evidence was obtained indicating that some factors support their quest for finding meaning in life in the workplace.
Health Studies
M.A. (Health Studies)
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Books on the topic "High-vacuum environment"

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Hong, M. H. Laser applications in nanotechnology. Edited by A. V. Narlikar and Y. Y. Fu. Oxford University Press, 2017. http://dx.doi.org/10.1093/oxfordhb/9780199533060.013.24.

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This article discusses a variety of laser applications in nanotechnology. The laser has proven to be one of many mature and reliable manufacturing tools, with applications in modern industries, from surface cleaning to thin-film deposition. Laser nanoengineering has several advantages over electron-beam and focused ion beam processing. For example, it is a low-cost, high-speed process in air, vacuum or chemical environments and also has the capability to fulfill flexible integration control. This article considers laser nanotechnology in the following areas: pulsed laser ablation for nanomaterials synthesis; laser nanoprocessing to make nanobumps for disk media nanotribology and anneal ultrashort PN junctions; surface nanopatterning with near-field, and light-enhancement effects; and large-area parallel laser nanopatterning by laser interference lithography and laser irradiation through a microlens array. Based on these applications, the article argues that the laser will continue to be one of the highly potential nanoengineering means in next-generation manufacturing.
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Book chapters on the topic "High-vacuum environment"

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Latham, R. V. "Potential Threats to the Performance of Vacuum-Insulated High-Voltage Devices in a Space Environment." In The Behavior of Systems in the Space Environment, 467–89. Dordrecht: Springer Netherlands, 1993. http://dx.doi.org/10.1007/978-94-011-2048-7_20.

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Michael, J. R. "Energy Dispersive X-Ray Spectrometry in Ultra-high Vacuum Environments." In X-Ray Spectrometry in Electron Beam Instruments, 83–99. Boston, MA: Springer US, 1995. http://dx.doi.org/10.1007/978-1-4615-1825-9_7.

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Iino, Y., M. Itoh, M. Omote, Y. Yamaguchi, and T. Ban. "Effects of High Temperature Gas Environments(H2, Pure Air, Ar, Vacuum) on Slow Strain Rate Tensile Properties at 700°C of TiAl Alloy." In The Mechanical Behavior of Materials X, 1007–10. Stafa: Trans Tech Publications Ltd., 2007. http://dx.doi.org/10.4028/0-87849-440-5.1007.

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"Cultural Initiatives." In Advances in Human Resources Management and Organizational Development, 74–85. IGI Global, 2012. http://dx.doi.org/10.4018/978-1-4666-0240-3.ch006.

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Organizational cultural initiatives are not limited to the internal culture of the organization but are influenced by the external culture within which the organization operates. Organizational culture is a relatively new type of organizational analysis that is borrowed from the field of anthropology. It first was described as an organizational unit of concern by Pettigrew (1979). Competitive organizations maintain their competitive advantage through their ability to effectively ?leverage high technology and people in the workplace. High technology and people do not exist in a ?vacuum. How has the environment or culture influenced the use of technology and people? The purpose of this chapter is to: (1) review the cultural initiatives including embedded in environment, adoption of cultural norms, leadership by inspiration, and evidence based management; and (2) present an analysis of issues and concerns related to managing people and technology in an environment that focuses upon a cultural perspective within the organizational process.
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Kumar Singh, Deependra, Basanta Kumar Roul, Karuna Kar Nanda, and Saluru Baba Krupanidhi. "Group III-Nitrides and Their Hybrid Structures for Next-Generation Photodetectors." In Light-Emitting Diodes and Photodetectors - Advances and Future Directions [Working Title]. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.95389.

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In the last few decades, there has been a phenomenal rise and evolution in the field of III–Nitride semiconductors for optoelectronic applications such as lasers, sensors and detectors. However, certain hurdles still remain in the path of designing high-performance photodetectors (PDs) based on III-Nitride semiconductors considering their device performance. Recently, a lot of progress has been achieved in devices based on the high quality epilayers grown by molecular beam epitaxy (MBE). Being an ultra-high vacuum environment based-technique, MBE has enabled the realization of high-quality and highly efficient PDs which have exhibited competitive figures of merit to that of the commercial PDs. Moreover, by combining the novel properties of 2D materials with MBE-grown III-Nitrides, devices with enhanced functionalities have been realized which would pave a way towards the next-generation photonics. In the current chapter, the basic concepts about photodetection have been presented in detail, followed by a discussion on the basic properties of the III-Nitride semiconductors, and the recent advancements in the field of MBE-grown III-Nitrides-based PDs, with an emphasis on their hybrid structures. Finally, an outlook has been provided highlighting the present shortcomings as well as the unresolved issues associated with the present-day devices in this emerging field of research.
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Krishnan, Kannan M. "Atomic Structure and Spectra." In Principles of Materials Characterization and Metrology, 68–146. Oxford University Press, 2021. http://dx.doi.org/10.1093/oso/9780198830252.003.0002.

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We review the structure of atoms to describe allowed intra-atomic electronic transitions following dipole selection rules. Inner shell ionization is followed by characteristic X-ray emission or non-radiative de-excitation processes leading to Auger electrons that involve three atomic levels. Photon incidence also results in characteristic photoelectron emission, reflecting the energy distribution of the electrons in the solid. We present details of laboratory and synchrotron sources of X-rays, and discuss their detection by wavelength or energy-dispersive spectrometers, as well as microanalysis with X-ray (XRF), or electron (EPMA) incidence. Characteristic X-ray intensities are quantified in terms of composition using corrections for atomic number (Z), absorption (A), and fluorescence (F). Electron detectors use electrostatic or magnetic dispersing fields; two common designs are electrostatic hemispheric or mirror analyzers. Auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS), used for surface analysis, require ultra-high vacuum. AES is a weak signal, best resolved in a derivative spectrum, shows sensitivity to the chemical state and the atomic environment, provides a spatially-resolved signal for composition mapping, and can be quantified for chemical analysis using sensitivity factors. Finally, we introduce the basics of XPS, a photon-in, electron-out technique, discussed further in §3.
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Modenese, C., S. Utili, and G. T. Houlsby. "A Study of the Influence of Surface Energy on the Mechanical Properties of Lunar Soil Using DEM." In Discrete Element Modelling of Particulate Media, 69–75. The Royal Society of Chemistry, 2012. http://dx.doi.org/10.1039/bk9781849733601-00069.

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DEM was employed to investigate the mechanical behaviour of Lunar Soil, generally defined as the finest fraction of the Lunar Regolith, taking into account the main effects of the lunar environment (e.g. high vacuum, low gravity and high temperature fluctuations). The purpose is to inform the planning of future lunar exploration, both manned and robotic. The investigation has focussed on the origins of the observed cohesion of Lunar Soil, whose explanation has proved elusive until now. The effects on the stress-strain behaviour of inter-particle attractive van der Waals forces (quantified by the surface energy) were investigated by means of triaxial compression tests in a periodic cell containing 5000 spherical particles. The particle radii vary according to the typical Particle Size Distribution of the Lunar Regolith. Very dense samples, with relative density approaching 100%, were prepared under isotropic compression. Triaxial tests were then carried out at constant mean pressure for very small confining stresses in the range of 0.1 kPa to 10 kPa, corresponding to a depth from the lunar surface of approximately 0.04 m to 4 m, respectively. To assess the effect of surface energy, simulations were run with and without the presence of inter-particle adhesion, which was introduced at the contact level by implementing the JKR model. The results show that the surface energy is responsible for an apparent macroscopic cohesion at the peak of the deviatoric stress-strain curve, but does not affect the tangent friction angle. However, at the critical state, very little cohesion (if any) was observed. Furthermore, an increase of the secant friction angle is apparent only at stresses less than 5 kPa. Physical explanations of these complex phenomena are postulated, and a link between microscopic and macroscopic physical variables is proposed.
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Wu, Zhiqiang, Kai Xu, Zhihuan Wang, Shuaiheng Li, and Baoying Jiang. "Soil-Water Separation Property of Bauxite Mine Slime." In Advances in Transdisciplinary Engineering. IOS Press, 2021. http://dx.doi.org/10.3233/atde210155.

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Traditional disposal of the high-water content slime from the beneficiating and washing of the bauxite mine requires lots of land and a long time to consolidate, which has attracted a wide range of environmental and social concerns. High-speed centrifugal test was carried out to investigate the water property and composition of high-water content bauxite washing mud. Test results indicated that the bound water content ranged from 29.7% to 31.4%, free water content ranged from 250.6% to 252.3%. The bound water accounted for only 11%, while the free water accounted for about 89% of total water content. A series of model tests were conducted to study the slurry-water separation property of high-water content bauxite mine slime. Experiments showed that controlling the vacuum load application process can effectively inhibit the formation of low-permeability stratum around the drainage body. The final settlement increased by 31.5% and the amount of water discharge increased by 39.52% compared with the conventional vacuum preloading method. Moreover, the water content may decrease from 281.9% to 53.6% within 60 hours with the increase of density of drainage body under the controlled vacuum load application process.
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Donnet, C., M. Belin, T. Le Mogne, and J. M. Martin. "Tribological behaviour of solid lubricated contacts in air and high-vacuum environments." In Tribology Series, 389–400. Elsevier, 1996. http://dx.doi.org/10.1016/s0167-8922(08)70800-9.

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Dispinar, Derya. "Melt Quality Assessment." In Encyclopedia of Aluminum and Its Alloys. Boca Raton: CRC Press, 2019. http://dx.doi.org/10.1201/9781351045636-120052503.

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It is well known that the reaction of liquid aluminum with the moisture in the environment results in two products: aluminum oxide and hydrogen gas that dissolves in aluminum. Both of these products are considered to be detrimental to the properties of aluminum alloys. Therefore, test equipment has been developed to check the levels of these defects in the melt. Many of these involve expensive and consumable tools. In addition, an experienced personnel may be required to interpret the results. Nonetheless, aluminum oxide is harmless as long as it remains on the surface. The problem begins when this oxide is entrained into the liquid aluminum such as turbulence during transfer or mold filling in a non-optimized design. This can only happen by folding of the oxide. During this action, rough surface of the oxides comes in contact to form no bonds. These defects are known as bifilms that have certain characteristics. First, they act as cracks in the cast parts since they are oxides. It is important to note that aluminum oxide has thin amorphous oxide (known as young oxides) and thick crystalline oxide (γ-Al2O3) that may be formed in a casting operation. Second, almost zero force is required to open these bifilms due to the unbonded folded oxide skins. Thus, these defects can easily form porosity by unravelling during solidification shrinkage. On the other hand, the formation of porosity by hydrogen is practically impossible. Theoretically, hydrogen has high solubility in the liquid but it has significantly low solubility in solid aluminum. Thus, it is suspected that hydrogen is rejected from the solidification front to form hydrogen gas and porosity. However, the hydrogen atom has the smallest atomic radii and high diffusibility. Therefore, segregation of hydrogen in front of the growing solid is difficult. In addition, the energy required for hydrogen atoms to segregate and form hydrogen gas molecule is around 30,000 atm. Under these conditions, porosity formation by hydrogen is not likely to be achieved. Hydrogen probably stays in a supersaturated state or diffuses homogeneously through the cast part. The effect of hydrogen can only be seen when it can diffuse into the unbonded gap between the bifilms to open them up to aid the unravelling of bifilms to form porosity. This phenomenon can be easily detected by a very simple test called reduced pressure test. When a sample is solidified under vacuum, the bifilms start to open up. Since all porosity is formed by bifilms, the cross section of the sample solidified under vacuum can be analyzed by means of image analysis software. The sum of maximum length of pores can be measured as an indication of melt quality. Since bifilms are the most detrimental defects, this value is called “bifilm index” given in millimetres, which makes this test the only test that can quantify aluminum melt quality in such detail including both the effects of bifilms and hydrogen together. Several Al-Si alloys were used at various conditions: degassing with lance, ceramic diffusers, and graphite rotary has been compared. Gravity sand casting, die casting, and low-pressure die casting methods were evaluated. The effect of grain refiners and modifiers was studied. And the evolution of the bifilm index has been presented.
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Conference papers on the topic "High-vacuum environment"

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Tavsanoglu, Ali, Cesar Briso, Rafael B. Arancibia, Montgomery Scott, and Diego Carmena-Cabanillas. "Wireless Communications in High Speed Vacuum trains environment for Vehicular Technology Conference." In 2021 IEEE 94th Vehicular Technology Conference (VTC2021-Fall). IEEE, 2021. http://dx.doi.org/10.1109/vtc2021-fall52928.2021.9625453.

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Montgomery, Jeff. "High Voltage Solid-Body Fuses for Use in Vacuum, Zero G, and Shock Environment." In Power Systems Conference. 400 Commonwealth Drive, Warrendale, PA, United States: SAE International, 2000. http://dx.doi.org/10.4271/2000-01-3600.

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Demsky, Steven M., Yoshimi R. Takeuchi, and James T. Dickey. "Thermal Conductance Measurement Techniques for High-Speed Bearings in Vacuum." In ASME 2005 Summer Heat Transfer Conference collocated with the ASME 2005 Pacific Rim Technical Conference and Exhibition on Integration and Packaging of MEMS, NEMS, and Electronic Systems. ASMEDC, 2005. http://dx.doi.org/10.1115/ht2005-72409.

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An experimental method has been developed at The Aerospace Corporation to determine the thermal conductance of moving bearings in vacuum. The test involves the measurement of thermal conductance of a single bearing under controlled inner race rotational speed, axial load, and thermal environment. Applications of interest include high-speed momentum wheels and flywheels. This paper covers the experimental method developed for this purpose and the techniques used to establish measurement uncertainty.
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He, Ben, Lin Yang, Yu-cong Yin, Xiao-long Lu, and Chun-sheng Zhao. "Research on performance of the Ultrasonic Motor under environment of vacuum and high/low temperature." In 2011 Symposium on Piezoelectricity, Acoustic Waves, and Device Applications (SPAWDA 2011). IEEE, 2011. http://dx.doi.org/10.1109/spawda.2011.6167191.

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Li, Xiyuan, Yabin Jian, Nianguo Sun, Ziyin Guo, Jing Wang, and Zhang Jingchuan. "System design and verification of high-speed camera system under extreme cryogenic and vacuum environment." In International Conference on Optical Instruments and Technology 2017: Advanced Optical Sensor and Applications, edited by Liquan Dong, Xuping Zhang, Hai Xiao, and Francisco Javier Arregui. SPIE, 2018. http://dx.doi.org/10.1117/12.2287587.

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Schuster, Gary B. A., John R. Zerwekh, James A. Davis, Peter J. Ring, Mohamed S. El-Genk, and Mark D. Hoover. "Measurement of Static and Dynamic Friction Coefficients for SP-100 Tribological Coatings in a High-Temperature/High-Vacuum Environment." In SPACE NUCLEAR POWER AND PROPULSION: Eleventh Symposium. AIP, 1994. http://dx.doi.org/10.1063/1.2950147.

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Zhang, Kai-lun, Ling Dai, and Ling-feng Xiang. "Design and test of the trigger vacuum switch and its trigger source for high temperature environment." In 2016 IEEE International Power Modulator and High Voltage Conference (IPMHVC). IEEE, 2016. http://dx.doi.org/10.1109/ipmhvc.2016.8012782.

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Saraceno, Clara J., Florian Emaury, Martin Hoffmann, Cinia Schriber, Matthias Golling, Thomas Südmeyer, and Ursula Keller. "Pushing the limits of high-power modelocked thin disk lasers by operating in a vacuum environment." In CLEO: Science and Innovations. Washington, D.C.: OSA, 2013. http://dx.doi.org/10.1364/cleo_si.2013.cth1h.4.

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Gottlieb, O. "Nonlinear Dynamics of a Noncontacting Atomic Force Microscope in Ultra-High Vacuum." In ASME 2003 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. ASMEDC, 2003. http://dx.doi.org/10.1115/detc2003/vib-48523.

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In this paper we formulate a nonlinear boundary-value problem describing thermoelastic dynamics of a microbeam for noncontacting Atomic Force Microscopy (AFM) that is operating in an ultra-high vacuum environment (UHV). A modal Galerkin projection yields a strongly nonlinear dynamical system that is governed by a planar homoclinic structure describing escape from a potential well. This structure is perturbed by both thermoelastic damping and modulated periodic actuation and reveals existence of local and global bifurcations and sheds light on possible thermoelastic instabilities leading to aperiodic dynamics.
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Kobayashi, Ken-ichi, and Sho Takei. "Influence of Testing Environment on SP Creep Rupture Lives." In ASME 2013 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/pvp2013-97545.

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Small Punch (SP) Creep test has been recognized as a semi destructive testing method to examine residual life of creep in high temperature components. Employing 2.25Cr-1Mo steel (SCMV4), SP creep tests were conducted at 600°C both in air and in high vacuum to examine the influence of oxidation on the long-term rupture life of the SP creep tests. As a test result, the creep rupture life in air was shorter than that in vacuum when the rupture life was less than 1000 hours. Reduction of rupture lives in air was approximately a half of them tested in vacuum. However when the creep rupture life was longer than 1000 hours, little difference emerged even if the testing atmosphere was different. A thickness of the oxide scale formed on SP creep specimens in air increased with the test duration. The experimental test results showed that the oxide scale affected on a coefficient of friction between the loading ball and the SP creep specimen. Furthermore the oxide scale formed in air did not always peel off from the test specimen, and the thick oxide scale endured a part of applied load in the longer life test.
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Reports on the topic "High-vacuum environment"

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Ceyer, S. T. High pressure heterogeneous catalysis in a low pressure ultrahigh vacuum environment. Office of Scientific and Technical Information (OSTI), January 1992. http://dx.doi.org/10.2172/6859215.

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Ceyer, S. T. High pressure heterogeneous catalysis in a low pressure ultrahigh vacuum environment. Summary of progress report, July 1, 1989--December 31, 1992. Office of Scientific and Technical Information (OSTI), December 1992. http://dx.doi.org/10.2172/10108262.

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