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41.
Z. Moser W. Gąsior K. Bukat J. Pstruś R. Kisiel J. Sitek K. Ishida I. Ohnuma 《Journal of Phase Equilibria and Diffusion》2006,27(2):133-139
Maximum bubble pressure, dilatometric, and meniscographic methods were used in the investigations of the surface tension,
density, wetting time, wetting force, contact angle, and interfacial tension of liquid alloys of Sn−Ag−Cu eutectic composition
with various additions of Bi. Density and surface tension measurements were conducted in the temperature range 250–900 °C.
Surface tensions at 250 °C measured under a protective atmosphere of Ar−H2 were combined with data from meniscographic studies done under air or with a protective flux. The meniscographic data with
a nonwetted teflon substrate provided data on interfacial tension (solder-flux), surface tension in air, and meniscographic
data with a Cu substrate allowed determinations of wetting time, wetting force, and calculation of contact angle. The calculated
wetting angles from meniscographic studies for binary Sn−Ag eutectic and two ternary Sn−Ag−Cu alloys were verified by separate
measurements by the sessile drop method under a protective atmosphere with a Cu substrate. Additions of Bi to both ternary
alloys improve the wettability and move the parameters somewhat closer to those of traditional Sn−Pb solders. 相似文献
42.
I. Ohnuma K. Ishida Z. Moser S. Gąsior K. Bukat J. Pstruś R. Kisiel J. Sitek 《Journal of Phase Equilibria and Diffusion》2006,27(3):245-254
The ADAMIS database was used for calculation of the surface tension of the quaternary Sn−Ag−Cu−Bi liquid alloys by Butler's
model. The resultant data were compared with those from the maximum bubble pressure measurements from Part I. The same thermodynamic
database was next applied for the calculation of various phase equilibria. It was established that the Bi addition to the
ternary Sn−Ag−Cu alloys (Sn-2.6Ag-0.46Cu and Sn-3.13Ag-0.74Cu in at.%; Sn-2.56Ag-0.26 Cu and Sn-2.86Ag-O.40Cu in mass%) causes
lowering of the melting temperature and the surface tension to make the tested alloys closer to, traditional Sn−Pb solders.
The simulation of the solidification by Scheil's model showed that the alloys with the higher Bi concentration are characterized
by the lifting-off failure due to the segregation of Bi at the solder/substrate boundary. Thus, in modeling of new Pb-free
solders, a compromise among various properties should be taken into consideration. 相似文献
43.
44.
The effects of silicon on the properties of tantalum 总被引:2,自引:0,他引:2
K. D. Moser B.S. T. K. Chatterjee M.S. P. Kumar Ph.D. 《JOM Journal of the Minerals, Metals and Materials Society》1989,41(10):50-53
The microalloying of tantalum with silicon has been effectively used on a commercial scale. However, data on effects of microalloying on processibility, microstructure and mechanical properties are not readily available. To develop some data, tantalum powder with various levels of silicon (0–50 ppm) was processed under identical conditions. Sheet samples were then annealed at different temperatures and evaluated via microstructural, chemical and mechanical tests. The recrystallization temperature was found to increase with silicon content, most probably as a result of the presence of an intermetallic (Ta3Si) phase. The mechanical properties of unrecrystallized tantalum are, as expected, significantly different from those of recrystallized tantalum. 相似文献
45.
Cornelia Kappeler-Setz Franz Gravenhorst Johannes Schumm Bert Arnrich Gerhard Tröster 《Personal and Ubiquitous Computing》2013,17(2):261-271
Manic depression, also known as bipolar disorder, is a common and severe form of mental disorder. The European research project MONARCA aims at developing and validating mobile technologies for multi-parametric, long term monitoring of physiological and behavioral information relevant to bipolar disorder. One aspect of MONARCA is to investigate the long term monitoring of Electrodermal activity (EDA) to support the diagnosis and treatment of bipolar disorder patients. EDA is known as an indicator of the emotional state and the stress level of a person. To realize a long-term monitoring of the EDA, the integration of the sensor system in the shoe or sock is a promising approach. This paper presents a first step towards such a sensor system. In a feasibility study including 8 subjects, we investigate the correlation between EDA measurements at the fingers, which is the most established sensing site, with measurements of the EDA at the feet. The results indicate that 88% of the evoked skin conductance responses (SCRs) occur at both sensing sites. When using an action movie as psychophysiologically activating stimulus, we have found weaker reactivity in the foot than in the hand EDA. The results also suggest that the influence of moderate physical activity on EDA measurements is low and has a similar effect for both recording sites. This suggests that the foot recording location is suitable for recordings in daily life even in the presence of moderate movement. 相似文献
46.
Fabien Tâche Wolfgang Fischer Gilles Caprari Roland Siegwart Roland Moser Francesco Mondada 《野外机器人技术杂志》2009,26(5):453-476
This paper describes the Magnebike robot, a compact robot with two magnetic wheels in a motorbike arrangement, which is intended for inspecting the inner casing of ferromagnetic pipes with complex‐shaped structures. The locomotion concept is based on an adapted magnetic wheel unit integrating two lateral lever arms. These arms allow for slight lifting off the wheel in order to locally decrease the magnetic attraction force when passing concave edges, as well as laterally stabilizing the wheel unit. The robot has the main advantage of being compact (180 × 130 × 220 mm) and mechanically simple: it features only five active degrees of freedom (two driven wheels each equipped with an active lifter stabilizer and one steering unit). The paper presents in detail design and implementation issues that are specific to magnetic wheeled robots. Low‐level control functionalities are addressed because they are necessary to control the active system. The paper also focuses on characterizing and analyzing the implemented robot. The high mobility is shown through experimental results: the robot not only can climb vertical walls and follow circumferential paths inside pipe structures but it is also able to pass complex combinations of 90‐deg convex and concave ferromagnetic obstacles with almost any inclination regarding gravity. It requires only limited space to maneuver because turning on the spot around the rear wheel is possible. This high mobility enables the robot to access any location in the specified environment. Finally the paper analyzes the maximum payload for different types of environment complexities because this is a key feature for climbing robots and provides a security factor about the risk of falling and slipping. © 2009 Wiley Periodicals, Inc. 相似文献
47.
Journal of Automated Reasoning - The word problem for a finite set of ground identities is known to be decidable in polynomial time using congruence closure, and this is also the case if some of... 相似文献
48.
Given the constantly raising world-wide energy demand and the accompanying increase in greenhouse gas emissions that pushes the progression of climate change, the possibly most important task in future is to find a carbon-low energy supply that finds the right balance between sustainability and energy security. For renewable energy generation, however, especially the second aspect turns out to be difficult as the supply of renewable sources underlies strong volatility. Further on, investment costs for new technologies are so high that competitiveness with conventional energy forms is hard to achieve. To address this issue, we analyze in this paper a non-autonomous optimal control model considering the optimal composition of a portfolio that consists of fossil and renewable energy and which is used to cover the energy demand of a small country. While fossil energy is assumed to be constantly available, the supply of the renewable resource fluctuates seasonally. We further on include learning effects for the renewable energy technology, which will underline the importance of considering the whole life span of such a technology for long-term energy planning decisions. 相似文献
49.
Christian Wolf Martin Prechtl René Bauer Michael Dinkel Fabian Beck Leopold Franz Viktor Neumeyer 《真空研究与实践》2023,35(1):35-39
To mark our anniversary, we are presenting articles that have been particularly appreciated by readers of our online edition once again in print. Here: 3D-Printing for High Vacuum Applications 3D printing technology has made the leap from a home-based private practice to industrial manufacturing. Due to the increasing reliability of printers and increasing material diversity, especially in the metal sector, double-digit percentage growth rates are possible in the coming years. This thesis deals with the manufacture of parts made by 3D printing for high vacuum application. Different components are printed and examined for their vacuum compatibility. As shown furthermore, conventionally made standard components can be vacuum sealed to printed parts, which enables cost-effective production of more complex components, such as e.g. a vacuum chamber allows. In addition, functional components can already be realized in the manufacturing process. The integration of a system of flow channels directly into the wall of a chamber is just one example. Thus, such a chamber can be heated during evacuation and effectively cool in later operation. 相似文献
50.