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Letteratura scientifica selezionata sul tema "Moving Metals Limited"

Autore: Grafiati

Pubblicato: 4 giugno 2021

Ultima modifica: 12 febbraio 2022

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Articoli di riviste sul tema "Moving Metals Limited"

Allen, J. W., M. S. Allen, D. C. Look, B. R. Wenner, N. Itagaki, K. Matsushima e I. Surhariadi. "Infrared Plasmonics via ZnO". Journal of Nano Research 28 (giugno 2014): 109–19. http://dx.doi.org/10.4028/www.scientific.net/jnanor.28.109.

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Conventional plasmonic devices involve metals, but metal-based plasmonic resonances are mainly limited to λres < 1 μm, and thus metals interact effectively only with light in the UV and visible ranges. We show that highly doped ZnO can exhibit λres ≥ 1 μm, thus moving plasmonics into the IR range. We illustrate this capability with a set of thin (d = 25–147 nm) Al-doped ZnO (AZO) layers grown by RF sputtering on quartz glass. These samples employ a unique, 20-nm-thick, ZnON buffer layer, which minimizes the strong thickness dependence of mobility (μ) on thickness (d). A practical waveguide structure, using these measurements, is simulated with COMSOL Multiphysics software over a mid-IR wavelength range of 4–10 μm, with a detailed examination of propagation loss and plasmon confinement dimension. In many cases, Lplas < λlight, thus showing that IR light can be manipulated in semiconductor materials at dimensions below the diffraction limit.

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Mehmood, Ahmer, Muhammad Saleem Iqbal e Irfan Mustafa. "Cooling of Moving Wavy Surface through MHD Nanofluid". Zeitschrift für Naturforschung A 71, n. 7 (1 luglio 2016): 583–93. http://dx.doi.org/10.1515/zna-2016-0044.

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AbstractHeat transfer analysis has been carried out in the Magnetohydrodynamic (MHD) boundary layer formed near the wavy rough plate moving in x-direction. Due to the presence of metallic nanoparticle in the fluid and enhanced surface area of the plate as a consequence of surface texture, an increase in heat transfer rates is expected. However, the calculation of these enhanced rates of heat transfer is not straightforward because the convection phenomena become more complicated due to the motion of nanoparticle in the base fluid and also the waviness of the plate surface. The contribution of nanoparticle toward convective heat transfer is manifold which requires a suitable model in order to capture the correct physics. Famous Tiwari and Das model has been utilised in the current study. Percent increase in the rate of heat transfer is calculated for the nanoparticle of different metals, such as MWCNT, SWCNT, Al2O3, TiO2 and Ag. Appreciable increase in the rate of heat transfer is observed, which is 24% at the most for Al2O3 nanoparticle. The effect of applied magnetic field on the velocity profile, skin friction coefficient, and Nusselt number has also been presented through graphs. The concentration of the nanoparticle has been limited up to 10%.

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Adams, P. M., e G. Radhakrishnan. "Microstructure of Pulsed-Laser Deposited Titanium Carbide Thin Films Grown for Tribological Applications". Microscopy and Microanalysis 7, S2 (agosto 2001): 1238–39. http://dx.doi.org/10.1017/s1431927600032268.

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The carbides and nitrides of transition metals, are excellent candidates for hard coatings for tribological applications. Recently a novel pulsed laser deposition (PLD) technique has been developed for the room temperature growth of particulate free titanium carbide (TiC) coatings on bearing steels. On a completely different scale from ball bearing applications, moving microelectricalmechanical systems (MEMS) face issues of limited lifetime as a result of rapid wear of the silicon components. The integration of hard tribological coatings into moving MEMS structures should greatly increase the functional lifetime of these devices. The same PLD technique has been used to deposit TiC thin film onto MEMS test structures consisting of multilayer coatings on Si substrates, and patterned 3-D Si substrates. This procedure for growing TiC appears to be compatible with conventional MEMS fabrication procedures.

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Zięba, P. "Recent Developments on Discontinuous Precipitation". Archives of Metallurgy and Materials 62, n. 2 (1 giugno 2017): 955–68. http://dx.doi.org/10.1515/amm-2017-0138.

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AbstractThe discontinuous precipitation (DP) belongs to a group of diffusive solid state phase transformations during which the formation of a new phase is heterogeneous and limited to a migrating reaction front (RF). The use of analytical electron microscopy provided reliable information that there is no differences in the diffusion rate at the stationary grain boundary and moving RF of DP reaction. On the other hand, the use of “in situ” transmission electron microscopy observations indicated the importance of stop-go motion or oscillatory movement of the RF.During 2004-2016 period more or less 280 papers were published in which the terms “discontinuous precipitation, “cellular precipitation”, discontinuous coarsening” appeared either in the abstract or in key-words.In the present contribution, the research on the DP reaction will be reviewed taking into account new aspects of theories and modelling, new evidences and findings, effect of various factors including third element, external stresses, plastic deformation and GB orientation, occurrence in less known systems and alloys like: superalloys, nitrided Fe-based alloys and Cu-based alloys. Finally, some suggestions for the future research will be formulated.

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Bernt, Marvin, e Adam McClure. "Consumable Anode Process for SnAg Electroplating". International Symposium on Microelectronics 2014, n. 1 (1 ottobre 2014): 000117–21. http://dx.doi.org/10.4071/isom-ta44.

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Near eutectic tin-silver (SnAg) is currently the alloy of choice for electroplated lead-free solder bumping and Cu pillar capping. While lead-tin (PbSn) is still used in some applications, there has been considerable momentum in moving away from the use of lead in semiconductor packaging. Both solders are normally electroplated as alloys with specific compositions to target a desired melting point. Since the deposition potentials of lead and tin are very close together, they plate with similar characteristics. This makes it possible for PbSn plating systems to use a consumable anode system where the anode composition matches the desired deposit composition. Metals are replenished into the bath in much the same ratio they are consumed. In a SnAg plating bath, the deposition potential of Ag is much more positive than Sn, so very low potential is required for Ag deposition. The plating rate of Ag is generally mass transfer limited. The plating rate of Sn is current controlled. While similar in concept to systems using consumable anodes for plating other metals, the SnAg alloy system presents some unique challenges. Because it is more noble, the Ag+ will deposit onto the Sn anode material by displacement reaction, and passivation will occur. Thus, the Sn anodes cannot come in contact with the Ag+ in the bath. Historically this problem is overcome by using an inert anode and metals replenishment by liquid concentrate. This paper outlines a method for plating SnAg using a consumable Sn anode, thereby reducing cost of ownership (CoO) and increasing bath stability compared to conventional SnAg wafer level packaging (WLP) plating.

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Adams, M. J., G. J. Ewen e C. A. Shand. "Acquisition and analysis of GFAAS data". Journal of Automatic Chemistry 10, n. 3 (1988): 130–34. http://dx.doi.org/10.1155/s1463924688000240.

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Since its inception as an analytical technique some 30 years ago atomic absorption spectrometry has become a firmly established method for the analysis of trace metals. Graphite furnace atomic absorption spectrometry provides the analyst with the capability of analysis of solutions containing μg l-1levels of the analyte, but, because of the transient nature of the signals, a sophisticated approach to the data aquisition and handling of data is required. Most modern commercial graphite furnace atomic absorption spectrometers have built in microprocessors for this purpose but they often have limited capability for extensible user programs and limited data storage facilities. In this communication we describe the use of an Apple IIe microcomputer for the acquisition of data from a Pye Unicam SP9 graphite furnace atomic absorption spectrometer. Details of the interface which utilizes an in-house designed AD converter, and an overview of the Pascal and assembler programs employed are given. The system allows the user to record, store and dump the graphical display of the furnace signalsfor all analyses performed. Files containing details of peak height, and area are formatted on an eight-column spreadsheet. Details of sample type, concentrations of standards, dilutions and replication are entered from the keyboard. The calibration graph is constructed using a moving quadratic fit routine and the concentrations of the analyte in unknown solutions calculated. In addition to this, greater processing power and integration of the data into other analytical schemes can be achieved by exporting the data to other software packages and computers. Details of data transfer between the Apple IIe and an Amstrad PC 1512 are given. Some examples of the use of the system in the development of an analytical methodfor silver in plant material are given.

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Safdar, S., L. Li, M. A. Sheikh e M. J. Schmidt. "Thermal history analysis of surface heating of mild steel with different laser beam geometries". Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 220, n. 10 (1 ottobre 2006): 1549–57. http://dx.doi.org/10.1243/09544062jmes246.

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Lasers are in use in the material processing industry for well over 30 years now. The way in which the temperature is distributed inside the material is of prime importance in laser material processing, as it directly affects the heating/cooling rates and thermal gradients. Optimization of different laser processes requires control over heating/cooling rate and thermal gradient. Different processes have different requirements of heating/cooling rate and thermal gradient. Knowing these parameters and relevant metallurgical information, one can predict the microstructure and hence control the material properties. To date, majority of laser processing is carried out by using either circular or rectangular beam. At present, the variation in temperature distribution to control the heating/cooling rates and thermal gradients is caused by the variation either in laser power or in scanning speed. Variations in these parameters are often limited by other processing conditions. Although different beam intensity distributions with circular or rectangular laser beams have been studied to improve the process, no other beam geometries have been investigated. The effect of laser beam geometry on laser processing of materials has received very little attention. This article presents an investigation of the effects of different beam geometries including circular, rectangular, and triangular shapes on heating of metallic materials. Finite-element modelling technique has been used to simulate the transient effects of a moving beam for laser surface heating of metals. The temperature distributions, cooling rates, and thermal gradients have been calculated. Some of the results have been compared with the experimental data.

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Harkness, Robert. "The Optical Radiation of Supernovae". International Astronomical Union Colloquium 89 (1986): 167–81. http://dx.doi.org/10.1017/s0252921100086073.

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Most of our knowledge of supernovae comes from studies of their optical radiation. Very high quality optical spectra have been available for several years now. The new data have aided the development of theoretical models of supernova explosions, particularly Type I events, which until recently, were very poorly understood. Type II explosions, which are believed to arise from core collapse in massive stars (Woosley, this volume;, produce optical spectra which can be simply interpreted in terms of a nearly blackbody continuum with prominent lines of hydrogen superimposed. The Type II atmosphere is of near solar composition, expanding at a characteristic velocity of 5000 km/s and at least bears some resemblance to a more familiar stellar atmosphere. Type I supernovae produce a much more violent expansion and the optical spectrum cannot be so easily accounted for. The progress made in the last few years stems mostly from the work of David Branch (Branch 1980,1981; Branch et. al. 1982,1983,1985). His synthetic spectra for Type I’s showed that the spectrum can be explained in terms of the resonance lines of mostly singly ionised metals. The lines are formed in matter moving with a bulk velocity of about 11,000 km/s and at a characteristic temperature of approximately 10,000 K. Furthermore, Branch concluded that the density profile in this region should be relatively steep and that the matter was very deficient in hydrogen and helium. As we shall see, this description fits very well with the hypothesis that Type I supernovae originate in the incineration of white dwarfs. Following the focus of recent developments this discussion will be mainly limited to the early evolution of Type I models of this kind, although many of the important features of the radiation transport are directly relevant to Type II explosions.

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Meier, Horst, V. Smukala, O. Dewald e Jian Zhang. "Two Point Incremental Forming with Two Moving Forming Tools". Key Engineering Materials 344 (luglio 2007): 599–605. http://dx.doi.org/10.4028/www.scientific.net/kem.344.599.

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This paper describes a new development of an incremental, robot based sheet metal forming process for the production of sheet metal components for limited-lot productions and prototypes. The kinematic based generation of the shape is implemented by means of two industrial robots, which are interconnected to a cooperating robot system. Compared to other incremental sheet metal forming machines this system offers a high geometrical form flexibility without the need of any workpiece dependent tools. The principle of the procedure is based on flexible shaping by means of a freely programmable path-synchronous movement of two robots. So far, the final shape is produced by the incremental infeed of the forming tool in depth direction and its movement along the contour in lateral direction on each level. The counter tool, with its simple geometry, was used to support the sheet metal on the backside by moving synchronously along the outer contour, constantly on the same level. This corresponds to a fixed backplate used in other incremental sheet metal forming processes. Due to the use of a new robot system with extended control algorithms for cooperating robots, it will be possible to release the counter tool from its constant path on the outer contour and support the forming tool right on the opposite side of the sheet to generate a predefined gap between the two hemispherical tools. This way at each moment a small part of a full die, as it is used in other processes, is simulated without the need of producing a workpiece dependent die. The extended payload of the new robot system gives the opportunity to form steel blanks, for the first time.

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Meier, Horst, e Christian Magnus. "Incremental Sheet Metal Forming with Direct Resistance Heating Using Two Moving Tools". Key Engineering Materials 554-557 (giugno 2013): 1362–67. http://dx.doi.org/10.4028/www.scientific.net/kem.554-557.1362.

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This paper describes new developments in an incremental, robot-based sheet metal forming process (‘Roboforming’) for the production of sheet metal components in small batch sizes. The dieless kinematic-based generation of a shape is implemented by means of two industrial robots which are interconnected to a cooperating robot system. Compared to other incremental sheet metal forming machines, this system offers high geometrical form flexibility without the need of any part-dependent tools. The industrial application of incremental sheet metal forming is still limited by certain constraints, e.g. the low geometrical accuracy and number of formable alloys. One approach to overcome the stated constraints is to use the advantages of metal forming at elevated temperatures. For the temperature input into the sheet metal, there are different approaches like heating with warm fluids, a laser beam or using direct resistance heating. This paper presents results of the research project ‘Local heating in robot-based incremental forming’, funded by the German Research Foundation (DFG), where the heating of the current forming zone by means of direct resistance heating is examined as a variation of the Roboforming process. In order to achieve a local limitation of the heating on the current forming zone, the electric current flows into the sheet at the electric contact of the forming tool and the sheet metal. Thus the forming tool is part of the electric circuit. In current literature Authors report about results from experiments using single-point incremental forming, where the forming tool and the clamping frame of the sheet are connected to the power source. In order to further limit the heating on the forming zone, a new approach will be presented in this paper, where a second tool is used to support the forming and heating process, as both tools can be connected to the power source, making a current flow through the rest of the sheet and the clamping frame unnecessary. With the use of two tools the current flow and thus the heated zone of the sheet can be manipulated. Additionally the advantages of the supporting tool, already shown in forming at room temperature, such as increased geometrical accuracy and maximum draw angle can be used. Starting with a description of the new process setup for steel forming at about 600 °C, results of experiments evaluating the influence of the supporting tool on the forming process at elevated temperatures and the resulting geometrical accuracy will be presented in this paper. Therefore, different process parameters as forming temperature, cooling and relative positioning of the both tools have been varied.

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Più fonti

Tesi sul tema "Moving Metals Limited"

Blewett, Verna. "Workers changing work : the influence of worker power ; a longitudinal case study analysis of workplace change at Moving Metals Limited /". Title page, contents and abstract only, 2000. http://thesis.library.adelaide.edu.au/public/adt-SUA20030815.104708.

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Bibliography: leaves 261-276. Electronic publication; full text available in PDF format; abstract in HTML format. This thesis is about the role that shop floor workers play in organisational change. In particular, it investigates the manner in which a distinct group of worker-level leaders and change agents affected the generation and implementation of change and helped to shape the change process in an organisation undergoing planned change. The data for the thesis were obtained from a three-year, longitudinal case-study of organisational change in a medium-sized automotive components manufacturer, Moving Metals Limited (MML). Electronic reproduction.[Australia] :Australian Digital Theses Program,2001.

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Blewett, Verna Lesley. "Workers changing work: the influence of worker power; a longitudinal case study analysis of workplace change at Moving Metals Limited". 2000. http://hdl.handle.net/2440/37904.

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This thesis is about the role that shop floor workers play in organisational change. In particular, it investigates the manner in which a distinct group of worker-level leaders and change agents affected the generation and implementation of change and helped to shape the change process in an organisation undergoing planned change. The data for the thesis were obtained from a three-year, longitudinal case-study of organisational change in a medium-sized automotive components manufacturer, Moving Metals Limited (MML). Data were collected at MML during a move from traditional mass production to lean production and the research was conducted using processual action research, while the researcher adopted the dual roles of researcher and consultant to the company. The research identified a distinct group of workers, with no supervisory capacity, who were able to shape the change process in the organisation. These workers are referred to as workers of influence. This group of workers emerged as central characters in the process of organisational change and as leaders and change agents in the organisation. Drawn from the empirical data, criteria for identifying workers of influence are developed in this thesis, based on the authority vested in them by the workforce and their access to management decision-making. A taxonomy of workers of influence is developed in this thesis using these criteria, as well as the duration of tenure of influence. In much of the literature, shop floor workers are portrayed as either passive participants in, or active resistors of organisational change. This research provides evidence of some workers acting as leaders and change agents in an active and influential manner. The research examines issues of power, influence, autonomy and control and their impact on workers' capacity to participate in change. In so doing, this research identifies and opens up an important area of study with implications for organisational theory, literature and the implementation of planned interventions in organisations.
Thesis (Ph.D.)--Department of Social Inquiry, 2000.

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Capitoli di libri sul tema "Moving Metals Limited"

van Santen, Rutger, Djan Khoe e Bram Vermeer. "Disaster Scenarios". In 2030. Oxford University Press, 2010. http://dx.doi.org/10.1093/oso/9780195377170.003.0037.

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A hurricane striking the Chinese coast is ten times as lethal as one hitting the United States. The number of U.S. victims is limited because of better precautions, warning systems, and evacuation methods. More effective observation and communication can save lives. A century ago, hurricanes killed around 7,000 Americans every year, whereas nowadays there are only very few hurricanes of the lethality of Katrina. That progress has yet to reach every corner of Earth, says Guus Berkhout regretfully. This Dutch geophysicist has immersed himself in the mechanisms of disasters and disaster prevention since the beginning of his scientific career—first as professor of seismic imaging and later as professor of innovation at Delft University of Technology in the Netherlands. We talked to him at the university campus that lies 3 meters below sea level. At his laboratory, Berkhout analyzes the early warning systems and contingency plans that will be needed to protect both his lab and his compatriots. “We can’t stop earthquakes, volcanic eruptions, hurricanes, or tidal waves from happening,” he stresses. “And we may never be able to predict hurricanes or earthquakes with sufficient accuracy. Nor can we hope to prevent people from living in dangerous places. They are simply too attractive.” Human beings indeed seem addicted to living on the edge of catastrophe. The World Bank has calculated that a fifth of all countries are under permanent threat of natural disaster, with some 3.4 billion people—roughly half the world’s population—at heightened risk of being killed by one. Yet unsafe regions are often exceptionally popular places to live and work, one reason being that floodplains and the slopes of volcanoes are highly fertile. The climate is milder along the coast, the soil better, and transport more efficient than farther inland. Even the likelihood of earthquakes isn’t enough to persuade people to live elsewhere, as witnessed by some of the most densely populated areas of California and Japan. Current migration trends—moving to where the action is—suggest that the proportion of people living in unsafe areas will only increase.

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"minutes retention depending on the oil processed. Then, Synthetic silica hydrogels: Described in the immediately the oil is heated to 70°C, (158°F) to assist "breaking" the preceding section. emulsion and the mixture is passed through a primary (first) centrifuge. The general dosage of acid-activated bleaching earths is 0.3-0.6%, depending on the quality of the oil and bleach-In contrast, the short-mix process, developed in Europe, ing earth. Bleaching earths provide catalytic sites for de-is conducted at 90°C (84°F), uses a more highly concen-composition of oxidation products. Peroxide values (mea-trated caustic, and a mixing time and primary centrifuging sure of aldehydes) and p-anisidine values (precursors for time of less than 1 minute [135]. Less heat damage to the oxidative degradation) first rise and then decrease during oil and higher refining yield are claimed by advocates of bleaching. Bleaching processes used include atmospheric the long mix process. batch, vacuum batch, and continuous vacuum. Vacuum 4. Silica Absorption bleaching has the advantage of excluding air, partially by In traditional refining, oil from the primary centrifuge is vaporization of water in the earth, and is recommended. A washed with warm soft water to remove residual soap and typical vacuum bleaching process is 20-30 minimum at passed through a (secondary) centrifuge. The washed oil 100-110°C (212-230°F) and 50 mmHg absolute [135]. then is dried under vacuum. However, disposal of wash The reactions catalyzed during bleaching continue into water is increasingly becoming a problem, and the indus-the filter bed and are known as the "press bleaching ef-try is shifting to a modified caustic "waterless" refining fect." The reactive components of oil remain in the bleach-process. Soaps poison the adsorption sites of clays in later ing bed. Care should be taken to "blow" the filter press as bleaching operations and are removed by silica hydrogels. free of oil as possible and to wet the filter cake (which can The oil may be degummed with use of chelating acids, be very dusty) to prevent spontaneous combustion [137]. caustic neutralized, passed through a primary centrifuge, At this point, the product is RB ("refined, bleached") and may be partially vacuum-dried. Synthetic silica hy-oil. If the intended product is an oil, it can be sent to the de-drogels, effective in removing 7-25 times more phos-odorizer and become RBD. If solids are desired, the solids-phatides and soaps than clay on a solids basis, and for re-temperature profile of the oil may be modified by hydro-moving phosphorus and the major metal ions, is added genation, interesterification, or chill fractionation, alone or and mixed with the oil. By absorbing these contaminants in combination. first, the bleaching clay is spared for adsorbing chloro-6. Hydrogenation phyll and the oxidation-degradation products of oil Hydrogenation is the process of adding hydrogen to satu-[136-138]. rate carbon-to-carbon double bonds. It is used to raise try-5. Bleaching glyceride melting points and to increase stability as by jective of bleaching is to remove various contami-converting linolenic acid to linoleic in soybean oil [141]. A The ob lighter, "brush" hydrogenation is used for the latter pur-nants, pigments, metals, and oxidation products before the pose. oil is sent to the deodorizer. Removal of sulfur is especial-Most of the catalysts that assist hydrogenation are nick-ly important before hydrogenation of canola and rapeseed el-based, but a variety is available for special applications. oils. Flavor of the oil also is improved. As mentioned in the "Selectivity" refers to ability of the catalyst and process to preceding section, silica hydrogels will adsorb many of sequentially saturate fatty acids on the triglycerides in the these contaminants and spare the bleaching earth. Howev-order of most unsaturated to the fully saturated. For row er, earths are still used for these purposes in installations crop oils, perfect selectivity would be: that have not adopted hydrated silicas. Types of bleaching materials available include [136,139,140]: C18:3 C18:2 C18:1 Linolenic acid Linoleic acid Oleic acid Neutral earths: Basically hydrated aluminum silicates, sometimes called "natural clays" or "earths," and C18:0 fuller's earth, which vary in ability to absorb pigments. Stearic acid Acid-activated earths: Bentonites or montmorillonites, Although typical hydrogenation is not selective, it can be treated with hydrochloric or sulfuric acid to improve favored to a limited degree by selection of catalyst and by their absorption of pigments and other undesirable temperature and pressure of the process. Efficient hydro-components, are most commonly used. genation requires the cleanest possible feed stock (without Activated carbon: Expensive, more difficult to use, but of soaps, phosphatides, sulfur compounds, carbon monoxide, special interest for adsorbing polyaromatic hydrocar-nitrogen compounds, or oxygen-containing compounds) bons from coconut and fish oils. and the purest, driest hydrogen gas possible [140]." In Handbook of Cereal Science and Technology, Revised and Expanded, 361–73. CRC Press, 2000. http://dx.doi.org/10.1201/9781420027228-35.

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Atti di convegni sul tema "Moving Metals Limited"

Brown, Chris, Jacqueline Krim e Art Morris. "Analysis of Cycle Lifetimes and Failure Modes for RF MEMS Switches". In World Tribology Congress III. ASMEDC, 2005. http://dx.doi.org/10.1115/wtc2005-63733.

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RF MEMS switch lifetimes are limited by stiction of the moving components and degradation of the metal to metal contact points during cycling. Currently, maximum switch lifetimes are around 10 to 25 billion cycles. Past experimentation has shown that some stiction problems can be overcome by carefully controlling the operating parameters, but problems at the contact points remain [1]. It is believed that by developing a set of tribological design rules which limit the factors leading to catastrophic failure, switches can operate in excess of 100 billion cycles. Recent research has quantified the reliability and durability of gold contact points on RF MEMS switches as a function of current [2]. Most experimentation on RF MEMS switches has focused on controlling the operating parameters such as current, voltage, electrode materials, contact area, switching mode and force; however, limited work has been performed on a single device type in multiple environmentally controlled testing conditions such as vacuum, cryogenic temperatures, etc. This presentation will discuss performance of the wiSpry RF MEMS switch focusing on quantification of device reliability and failure mechanisms under various atmospheric and temperature conditions. Environmental testing conditions include switching in open air, vacuum and inert gasses, in temperatures ranging from 294 K to 4 K.

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Zheng, Z. Charlie, e Guoyi Ke. "A Moving Zonal Method in the Time-Domain Simulation for Acoustic Propagation". In ASME 2010 International Mechanical Engineering Congress and Exposition. ASMEDC, 2010. http://dx.doi.org/10.1115/imece2010-39652.

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Conventional time-domain schemes have limited capability in modeling long-range acoustic propagation because of the vast computer resources needed to cover the entire region of interest with a computational domain. Many of the long-range acoustic propagation problems need to consider propagation distances of hundreds or thousands of meters. It is thus very difficult to maintain adequate grid resolution for such a large computational domain, even with the state-of-the-art capacity in computer memory and computing speed. In order to overcome this barrier, a moving zonal-domain approach is developed. This concept uses a moving computational domain that follows an acoustic wave. The size and interval of motion of the domain are problem dependent. In this paper, an Euler-type moving domain in a stationary coordinate frame is first tested. Size effects and boundary conditions for the moving domain are considered. The results are compared and verified with both analytical solutions and results from the non-zonal domain. Issues of using the moving zonal-domain with perfectly-matched layers for the free-space boundary are also discussed.

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Zhou, J., H. L. Tsai e P. C. Wang. "Modeling the Transport Phenomena in Moving 3-D Dual-Beam Laser Keyhole Welding". 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/ht2005-72201.

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In recent years, laser-beam welding using two laser beams, or dual-beam laser welding, has become an emerging welding technique. Previous studies have demonstrated that it can provide benefits over conventional single-beam laser welding, such as increasing keyhole stability, slowing down cooling rate and delaying the humping onset to a higher welding speed. It is reported that the dual beam laser welding can significantly improve weld quality. However, so far the development of the dual-beam laser welding technique has been limited to the trial-and-error procedure. In this study, the objective is to develop mathematical models and the associated numerical techniques to investigate the transport phenomena, such as heat transfer, metal flow, keyhole formation and weld pool shape evolutions during the moving three-dimensional dual-beam laser keyhole welding. Detailed studies have been conducted to determine the effects of key parameters, such as laser-beam configuration on weld pool fluid flow, weld shape, and keyhole dynamics. Some experimentally observed phenomena, such as the changes of the weld pool shape from oval to circle and from circle to oval during the welding process are predicted and can be well explained by the present model.

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Karami, M. Amin, e Daniel J. Inman. "Controlled Buckling of Piezoelectric Beams for Direct Energy Harvesting From Passing Vehicles". In ASME 2012 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/detc2012-71022.

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A piezoelectric device is introduced and modeled to directly interact with the tires of passing vehicles and generate electrical power for roadside applications. Piezoelectric beams are vertically placed on the surface of the road to generate energy from the load of passing vehices. A metal cap is connected to the top end of the bimorphs. The vertical motion of the metal cap is limited by the containing fixture of the device. Tires of the passing vehicles pass over the metal cap and force the bimorph into buckling. The buckling of the piezoelectric beam generates significant amount of power. By controlling the extent of deformation of the beam we make sure that the beam is not damaged by the buckling. To this end, the amount of axial recession of the metal cap (equal to axial deformation of the beam) is precision controlled by the containing fixture. When the beam deflects it axially shrinks due to geometric nonlinearities. This lowers the metal cap. After a certain amount of deformation the metal cap rests on the containing fixture and the tire load is no more transmitted to the piezoelectric beam. In this paper the performance of the proposed energy harvesting device is analytically modeled. Geometric nonlinearities and piezoelectric couplings have been included in the model. The vibrations of the device are transient. Power is generated when the tire pushes down the metal cap and when the metal cap springs back after the tire has passed. The design criteria for the device are discussed. It is demonstrated that the device can be realized with commonly used piezoelectric patches and can generate hundreds of milliwatts from the moving traffic. The device is not prone to resonance and generates notable amounts of power from passing of each tire. It therefore can be used as a self-sufficient sensor for traffic control.

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Dinovitzer, Aaron, Abdelfettah Fredj e Millan Sen. "Pipeline Stress Relief and Evaluation of Strain Measurement Technology at a Moving Slope". In 2014 10th International Pipeline Conference. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/ipc2014-33497.

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A major slope in southern Manitoba has been experiencing deep seated movements of approximately 60mm per year. This 24m high × 85m long slope contains a pipeline right of way with five large diameter crude oil lines that were constructed from 1950–1998. It is estimated that the slope has moved up to 3 meters since the pipeline installations. Management of the effects of this slope movement on the pipelines has involved cross-functional strategies that include geotechnical, integrity, and stress evaluations. A finite element analysis (FEA), which considers the interaction between the soil movement and pipeline, was generated to evaluate the pipeline stresses caused by the slope movements to date. The results indicated that the strain capacity on one of the pipelines may be near its limit. Correspondingly and in order to be conservative, a stress relief was conducted on three of the pipelines within the right-of-way. This mitigation involved excavating the pipelines 360 degrees which allowed for their decoupling from the surrounding soil, and the associated pipeline spring back was surveyed. Prior to backfilling, a low friction geotextile was installed around the excavated pipelines to help mitigate future movements. Drainage improvements and a toe berm were also installed to improve the slope stability. Several strain measurement technologies that have been the subject of previous Pipeline Research Council projects were also installed at the site. Stress probe measurements were taken before and after the stress relief; a fiber optic cable was installed; inline inspection bending strain measurements were analyzed; and the FEA analysis was used to model the strains before and after the stress relief. All of these technologies are compared to the measurements from strain gauges that were read both before and after the stress reliefs were conducted.

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Katterbauer, Klemens, Alberto Marsala, Virginie Schoepf e Linda Abbassi. "DOPPLER VS. SPINNER PLT SENSING FOR HYDROCARBON VELOCITY ESTIMATE BY DEEP-LEARNING APPROACH". In 2021 SPWLA 62nd Annual Logging Symposium Online. Society of Petrophysicists and Well Log Analysts, 2021. http://dx.doi.org/10.30632/spwla-2021-0003.

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Logging hydrocarbon production potential of wells has been at the forefront of enhancing oil and gas exploration and maximize productivity from oil and gas reservoirs. A major challenge is accurate downhole fluid phases flow velocity measurements in production logging (PLT) due to the criticality of mechanical spinner-based sensor devices. Ultrasonic Doppler-based sensors are more robust and deployable either in wireline or logging while drilling (LWD) conditions; however, due to the different sensing physics, the measurement results may vary. Ultrasonic Doppler flow meters utilize the Doppler effect that is a change in frequency of the sound waves that are reflected on a moving target. A common example is the change in pitch when a vehicle sounding a horn approaches and recedes from an observer. The frequency shift is in direct proportion of the relative velocity of the fluid with respect to the emitter-receiver and allows to infer the speed of the flowing fluid. Doppler flow meters offer many advantages over mechanical spinners such as the ability to measure without requiring calibration passes, the absence of mechanical moving parts, the sensors robustness to shocks and hits, easy installation and minimal affection by changes in temperature, density and viscosity of the fluid thus capability to work even in highly contaminated conditions such as tar, asphaltene deposits on equipment. Despite being widely used in surface flow metering, ultrasonic Doppler sensor applications to downhole environment have been so far very limited. We present in this work an innovative deep learning framework to estimate spinner phase velocities from Doppler based sensor velocities. Tests of the framework on a benchmark data set displayed strong estimation results, in particular outlining the ability to utilize Doppler-based sensors for downhole phase velocity measurements and allows the comparison of the estimates with previously recorded spinner velocity measurements. This allows for the real-time automated interpretative framework implementation and flow velocity estimations either in conventional wireline production logging technologies and potentially also in LWD conditions, when the well is flowing in underbalanced conditions.

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Zhou, J., H. L. Tsai e P. C. Wang. "Transport Phenomena and the Associated Humping Formation in Laser Welding". In ASME 2005 International Mechanical Engineering Congress and Exposition. ASMEDC, 2005. http://dx.doi.org/10.1115/imece2005-81766.

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Humping is a frequently observed welding defect in laser welding which is caused when the welding speed exceeds a certain limit while the other welding conditions remain unchanged. Humping is characterized by the appearance of unsmooth and discontinuity of humps at the surface of the weld. The formation of humping is generally understood to be caused by the complex heat transfer and melt flow in a high speed welding process. However, so far the fundamental mechanisms causing humping are not fully understood, and research on determining the onset of humping has been based on the “trial-and-error” procedure. In this paper, mathematical models previously developed by the authors for the transport phenomena in laser welding have been extended to investigate the formation of the humping defect. In this study, the transient heat transfer and melt flow in the weld pool during the keyhole formation and collapse, and melt solidification are calculated for a 3-D moving laser welding. Different humping patterns have been predicted by the present study in different laser power levels and welding speeds. From the present study, it was found that the formation of humping in laser welding is caused by the interplay between two important factors: a) the strong liquid metal flow in the real part of the keyhole induced mainly by the laser recoil pressure and b) the rapid solidification rate of the liquid metal. The humping pattern can be well explained by the calculated melt flow and the solidification process.

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Farooq, Khalid. "Varnish Removal and Control in Turbine Lubrication Systems". In ASME 2009 Power Conference. ASMEDC, 2009. http://dx.doi.org/10.1115/power2009-81173.

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Varnish deposits on metal surfaces in turbine lube system results in a number of adverse operational issues, especially the restriction and sticking of moving mechanical parts such as servo or directional control valves. The oil has limited solvency for the material, hence a typical turbine will have the majority of the material as deposits and a relatively small portion as suspended material in the oil phase in quasi-equilibrium with the deposits. The lube system needs to be cleaned by removing the suspended varnish precursors from the oil phase, which allows the deposits to re-entrain into the oil phase, until the majority of the transferable deposits from internal surfaces are removed and the oil carries no significant amount of the material to have any adverse effect. The methods used for the removal of varnish from turbine lube oil systems include chemical cleaning - flushing, and electrostatic charge induced agglomeration - retention and the adsorption of the oil suspended varnish on an adsorbent medium. The paper discusses an absorption based removal method that utilizes a fibrous medium that has pronounced affinity for the removal and retention of the varnish forming material from the oil and the deposits from surfaces that are in quasi-equilibrium with the varnish precursors in the oil. The filtration medium is composite cellulose with specially formulated, temperature cured binder resins. The absorptive medium that exhibits high structural and chemical integrity has been thoroughly tested on operating turbines, showing reduction in varnish levels from critical range to below normal range in a relatively short time. The experiences with the utilization of the absorptive medium in laboratory tests and in two operating turbines are presented.

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Shirakawa, Noriyuki, Yasushi Uehara, Masanori Naitoh, Hidetoshi Okada, Yuichi Yamamoto e Seiichi Koshizuka. "Next Generation Safety Analysis Methods for SFRs—(5) Structural Mechanics Models of COMPASS Code and Verification Analyses". In 17th International Conference on Nuclear Engineering. ASMEDC, 2009. http://dx.doi.org/10.1115/icone17-75532.

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A five-year research project started in FY2005 (Japanese Fiscal Year, hereafter) to develop a code based on the Moving Particle Semi-implicit (MPS) method for detailed analysis of core disruptive accidents (CDAs) in sodium-cooled fast reactors (SFRs). The code is named COMPASS (Computer Code with Moving Particle Semi-implicit for Reactor Safety Analysis). CDAs have been almost exclusively analyzed with SIMMER-III [2], which is a two-dimensional multi-component multi-phase Eulerian fluid-dynamics code, coupled with fuel pin model and neutronics model. The COMPASS has been developed to play a role complementary to SIMMER-III in temporal and spatial scale viewpoint; COMPASS for mesoscopic using a small window cut off from SIMMER-III for macroscopic. We presented the project’s outline and the verification analyses of elastic structural mechanics module of the COMPASS in ICONE16 [1]. The COMPASS solves physical phenomena in CDAs coupling fluid dynamics and structural dynamics with phase changes, that is vaporization/condensation and melting/ freezing. The phase changes are based on nonequilibrium heat transfer-limited model and all “phase change paths” considered in SIMMER-III are implemented [20]. In FY2007, the elastoplastic model including thermal expansion and fracture are formulated in terms of MPS method and implemented in the COMPASS, where the model adopts the von Mises type yield condition and the maximum principal stress as fracture condition. To cope with large computing time, “stiffness reduction approximation” was developed and successfully implemented in the COMPASS besides parallelization effort. Verification problems are set to be suitable for analyses of SCARABEE tests, EAGLE tests and hypothetical CDAs in real plants so that they are suggesting issues to be solved by improving the models and calculation algorithms. The main objective of SCARABEE-N in-pile tests was to study the consequences of a hypothetical total instantaneous blockage (TIB) at the entrance of a liquid-metal reactor subassembly at full power [21]. The main objectives of the EAGLE program consisting of in-pile tests using IGR (Impulse Graphite Reactor) and out-of-pile tests at NNC/RK are; 1) to demonstrate effectiveness of special design concepts to eliminate the re-criticality issue, and 2) to acquire basic information on early-phase relocation of molten-core materials toward cold regions surrounding the core, which would be applicable to various core design concepts [22, 23]. In this paper, the formulations and the results of functional verification of elastoplastic models in CDA conditions will be presented.

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Ren, Huaqing, Newell Moser, Zixuan Zhang, Kornel F. Ehmann e Jian Cao. "Effects of Tool Deflection in Accumulated Double-Sided Incremental Forming Regarding Part Geometry". In ASME 2016 11th International Manufacturing Science and Engineering Conference. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/msec2016-8839.

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Abstract (sommario):

Incremental forming is a flexible dieless forming process. In incremental forming, the metal sheet is clamped around its periphery. One or multiple generic stylus-type tools move along a predefined toolpath, incrementally deforming the sheet metal into a final, freeform shape. Compared with the traditional sheet metal forming process, the incremental forming process is more flexible, energy efficient and cost effective due to lower capital investment related to tooling. However, maintaining tight geometric tolerances in incremental formed parts can be a challenge. Specifically, undesired global bending is usually induced near the region between the tools and fixture resulting in a compromise in geometric accuracy. To address this issue, Accumulated Double-Sided Incremental Forming (ADSIF) is proposed, which utilizes two tools on both sides of the metal to better achieve localized deformation while simultaneously constraining global bending outside the forming area. Moreover, in ADSIF, the two tools are moving from inward to outward, and thus the tools are always forming virgin material and so as to limit forces on the already-formed part. Thus, ADSIF has a higher potential to achieve the desired geometry. Nevertheless, tool deflection due to machine compliance is still an issue that can have a considerable effect on geometric accuracy. In this work, the effect of tool deflection related to part geometry is studied for the ADSIF process. The nature of using two tools, rather than one, in ADSIF inherently implies that relative tool position is a critical process parameter. It is the region near these two tools where local squeezing and bending of the sheet occurs, the primary modes of deformation found in ADSIF. The change of relative tool positions (i.e., tool gap and relative position angle) are studied in detail by first developing an analytical model. It is concluded that the tool gap will be enlarged under the influence of tool compliance while the relative position angle is less affected. Additionally, a finite element simulation capable of modeling tool deflection is established. The comparison between the simulation results using rigid tools and deformable ones clearly demonstrated the significant influence of tool compliance on part geometry. Lastly, an axisymmetric part with varying wall angles was formed, and it was confirmed that ADSIF demonstrates improved geometry accuracy compared with conventional Double-Sided Incremental Forming.

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