150 research outputs found
Assigning Robust Default Values in Building Performance Simulation Software for Improved Decision-Making in the Initial Stages of Building Design
No full textApplying data mining techniques on a database of BIM models could provide valuable insights in key design patterns implicitly present in these BIM models. The architectural designer would then be able to use previous data from existing building projects as default values in building performance simulation software for the early phases of building design. The author has proposed the method to minimize the magnitude of the variation in these default values in subsequent design stages. This approach maintains the accuracy of the simulation results in the initial stages of building design. In this study, a more convincing argument is presented to demonstrate the significance of the new method. The variation in the ideal default values for different building design conditions is assessed first. Next, the influence of each condition on these variations is investigated. The space depth is found to have a large impact on the ideal default value of the window to wall ratio. In addition, the presence or absence of lighting control and natural ventilation has a significant influence on the ideal default value. These effects can be used to identify the types of building conditions that should be considered to determine the ideal default values
Synthesis of Mo–Si–B in situ composites by mechanical alloying
No full textIn this study, the synthesis of Mo-Si-B multi-phase alloys, so-called in-situ composites, was attempted with the combination of mechanical alloying (MA) and spark plasma sintering (SPS) processes. MA was conducted with mixed powders of Mo, Si and B using a planetary ball mill under various milling conditions. MAed powders were characterized by X-ray diffractometry (XRD) and scanning electron microscopy (SEM). The results obtained by XRD indicated that Mo-Si-B alloyed powders were successfully produced when elemental powders were milled at a higher milling energy. Vacuum heat treatments after the MA process promoted the formation of Mo-Si-B intermetallic phase in MAed powders. On the other hand, the MAed powders were successfully consolidated by a SPS technique, and as a result, sound compacts of Mo5SiB2-based composites were synthesized
Oxidation behavior of Mo-Si-B in-situ Composites
No full textIsothermal oxidation behavior of Al added Mo-Si-B in-situ composites was investigated under Ar-20%O2 and air atmosphere over the temperature range of 1073–1673 K. The Al added Mo-Si-B composites ((Mo-8.7mol%Si-17.4mol%B)-1mol%Al) were prepared by arc-melting, and homogenized at 2073 K for 24 h in an Ar-flow atmosphere. The ternary Mo-Si-B in-situ composite exhibited a rapid mass loss at the initial oxidation stage and then the passive oxidation after the substrates were sealed with borosilicate glass in the temperature range of 1173–1473 K, whereas it exhibited a rapid mass gain around 1073 K. On the other hand, the Al addition significantly improved the oxidation resistance of Mo-Si-B in-situ composites at temperatures from 1073–1573 K. These excellent oxidation resistances are considered to be due to the rapid formation of a continuous, dense scale of Al-Si-O complex oxides.Proceedings of the International Workshop on Designing of Interfacial Structures in Advanced Materials and their Joints, May, 18-20, 2006, held in Osaka, Japa
Microstructure and Mechanical Properties of the ZrC-Added Mo-Si-B Alloys Prepared by Arc-Melting
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Influence of vacuum annealing conditions on the surface oxidation and vacancy condensation in the surface of an FeAl single crystal
No full textThe influence of annealing atmosphere, temperature and time on the surface oxidation and vacancy condensation behavior of {111}-oriented single crystals of B2-type FeAl was investigated. AFM observation showed that as-annealed surfaces under a high vacuum were rugged and covered with a thin oxide film. The results obtained by TEM indicated that the thin oxide film was {001}-oriented κ-Al2O3 epitaxially grown on the {111}-oriented FeAl surface. AES measurements showed that the thickness of the oxide film was almost twice as thick as that of the passive Al2O3 film formed on the FeAl surface in an ambient atmosphere. It was found that the growth of surface mesopores is attributable to both the condensation of supersaturated vacancies in FeAl substrate and the Kirkendall effect by the surface oxidation during the vacuum annealing
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