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排序方式: 共有6045条查询结果,搜索用时 15 毫秒
91.
S. Kolossov E. Boillat R. Glardon P. Fischer M. Locher 《International Journal of Machine Tools and Manufacture》2004,44(2-3):117-123
A thermal model of selective laser sintering (SLS) has been developed. The model allows for the non-linear behavior of thermal conductivity and of specific heat due to temperature changes and phase transformations. The temperature evolution and the formation of the sintered part are simulated by a 3D finite element analysis based on continuous media theory. It is shown that the effect of sintering has a strong influence on thermal evolution through changing the thermal properties of the material. The results of the model were experimentally tested and confirmed by temperature measurements. 相似文献
92.
E. Fischer 《Journal of Phase Equilibria and Diffusion》1997,18(4):338-343
The O-Ti binary system has been assessed to produce Gibbs energy parameters for the condensed phases and were evaluated as
representations of thermodynamic models. The liquid phase was described in terms of an association model with one associate,
the bcc, A
2; cph,
A
3 and fcc,
A 1 phases were described as interstitial solid solutions, and the O2Ti, O3Ti5, O3Ti2, and OTi oxides were considered to be stoichiometric compounds. The thermodynamic parameters were optimized taking into account
experimental phase diagram and thermodynamic values from the literature. The phase diagram and the thermodynamic properties
were calculated and compared with experimental data. 相似文献
93.
Permeation transients for hydrogen, generated by corrosion of iron in dilute solutions of sulfuric acid, were recorded with an improved electrochemical permeation apparatus.The mechanism of the hydrogen evolution reactions is coupled discharge hydrogen recombination for all methods of hydrogen generation, low current anodic polarization, cathodic polarization and corrosion.The experimental hydrogen transient was compared with that predicted theoretically.It is concluded that electrochemical hydrogen permeation is a sensitive tool for investigating processes on metal surfaces which are of engineering importance. 相似文献
94.
Arvind Agarwal Tim McKechnie Sudipta Seal 《JOM Journal of the Minerals, Metals and Materials Society》2002,54(9):42-44
Research Summary Nanostructured ceramics and their composites possess improved properties such as tensile strength, fatigue
strength, hardness, and wear resistance. Freestanding, near-net shape, nanostructured Al2O3 components can be synthesized via plasma-spray forming. In this study, plasma-spray parameters were optimized and an innovative
substrate cooling technique was developed to retain nanosize Al2O3 in the spray deposit. Nanosize Al2O3 particles were partially melted and trapped between the fully melted coarser, micrometersize Al2O3grains. Densification of the spray-deposited Al2O3occurred via solidification and sintering. A similar processing approach can be adopted for fabrication of near-net shapes
of a variety of nanostructured materials (metals, ceramics, and intermetallics) and their combinations by selecting suitable
powder-treatment and plasmaspray parameters. 相似文献
95.
E. Fischer 《Journal of Phase Equilibria and Diffusion》2003,24(3):228-235
The values of the thermodynamic properties of the liquid phase of the AgCl-KCl and BaCl2-LiCl systems were optimized taking into account all the available experimental thermochemical and phase diagram information
from the literature. Each liquid was described as a substitutional solution, and a Redlich-Kister formalism was used for the
excess Gibbs energy. 相似文献
96.
As the number of messages and social relationships embedded in social networking sites (SNS) increases, the amount of social information demanding a reaction from individuals increases as well. We observe that, as a consequence, SNS users feel they are giving too much social support to other SNS users. Drawing on social support theory (SST), we call this negative association with SNS usage ‘social overload’ and develop a latent variable to measure it. We then identify the theoretical antecedents and consequences of social overload and evaluate the social overload model empirically using interviews with 12 and a survey of 571 Facebook users. The results show that extent of usage, number of friends, subjective social support norms, and type of relationship (online-only vs offline friends) are factors that directly contribute to social overload while age has only an indirect effect. The psychological and behavioral consequences of social overload include feelings of SNS exhaustion by users, low levels of user satisfaction, and a high intention to reduce or even stop using SNS. The resulting theoretical implications for SST and SNS acceptance research are discussed and practical implications for organizations, SNS providers, and SNS users are drawn. 相似文献
97.
98.
Librarians can improve their online tutorials by borrowing usability testing techniques from the computer science field to improve the human-computer interface. This study involved a multimethod usability test of librarian-created tutorials to determine what students learned, how they felt on several affective questions, and what they suggested for improving the tutorials. Results of pre- and post-tests showed that student knowledge increased, and surveys and focus group findings lean to several suggestions for improving engagement and placing tutorials where they will be most effective. This case study demonstrates the value of user input to improve the effectiveness of online instruction for information literacy. 相似文献
99.
Learning about the opponent in automated bilateral negotiation: a comprehensive survey of opponent modeling techniques 总被引:1,自引:0,他引:1
Tim Baarslag Mark J. C. Hendrikx Koen V. Hindriks Catholijn M. Jonker 《Autonomous Agents and Multi-Agent Systems》2016,30(5):849-898
A negotiation between agents is typically an incomplete information game, where the agents initially do not know their opponent’s preferences or strategy. This poses a challenge, as efficient and effective negotiation requires the bidding agent to take the other’s wishes and future behavior into account when deciding on a proposal. Therefore, in order to reach better and earlier agreements, an agent can apply learning techniques to construct a model of the opponent. There is a mature body of research in negotiation that focuses on modeling the opponent, but there exists no recent survey of commonly used opponent modeling techniques. This work aims to advance and integrate knowledge of the field by providing a comprehensive survey of currently existing opponent models in a bilateral negotiation setting. We discuss all possible ways opponent modeling has been used to benefit agents so far, and we introduce a taxonomy of currently existing opponent models based on their underlying learning techniques. We also present techniques to measure the success of opponent models and provide guidelines for deciding on the appropriate performance measures for every opponent model type in our taxonomy. 相似文献
100.
Kavita Krishnaswamy Ravi Kuber Tim Oates 《Universal Access in the Information Society》2016,15(4):609-627
Limb repositioning is necessary for individuals with severe physical disabilities to sustain muscle strength and prevent pressure sores. As robotic technologies become ubiquitous, these tools offer promise to support the repositioning process. However, research has yet to focus on ways in which individuals with severe physical disabilities can control robots for these tasks. This paper presents a study that examines the needs and attitudes of potential users with physical disabilities to control a robotic aid for limb repositioning. Subjects expressed interest in using brain–computer interface (BCI) and speech recognition technologies for purposes of executing robotic tasks. The performance of four subjects controlling arm movements on an avatar through the keyboard, mouse, BCI, and Dragon NaturallySpeaking speech recognition was evaluated. Although BCI and speech technologies may limit physical fatigue, more challenges were faced using BCI and speech conditions compared to the keyboard and mouse. This research promotes accessibility into mainstream robotic technologies and represents the first step in the development of a robotic prototype using a BCI and speech recognition technologies for limb repositioning. 相似文献