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991.
James T. Cahill James P. Kelly Ekaterina Novitskaya Michael McKee Joel A. Bahena Olivia A. Graeve 《Journal of the American Ceramic Society》2019,102(2):595-601
We describe the phase stability of a cemented tungsten carbide prepared using a high-vanadium tool steel as the cementing/binder phase and confirm suppression of (Fe, W)6C η-phase formation, attributed to the preferential formation of a V0.78W0.22C1−x phase that exists as islands within the Fe-rich binder matrix. The samples were prepared using spark plasma sintering (SPS), starting from commercially available WC and A11-LVC tool steel powders. The starting powders were ball milled adding 10, 15, and 20 vol.% steel. An A11-LVC tool steel was chosen as a low-cost hard steel (49 HRC) that does not contain Ni or Co but has a high vanadium (~9 wt.%) and carbon (~1.75 wt.%) content. Our results show that sintering by SPS can produce high-density (>98%) WC-steel specimens in which the matrix wets the WC grain surfaces and formation of the brittle η-phase is avoided. The η phase is often regarded as embrittling and undesirable, and its presence can result in degradation of mechanical properties. Microhardness values for the WC-10 and WC-15 vol.% steel samples were 12.3 ± 1.2 and 13.0 ± 0.9 GPa, respectively, whereas the fracture toughness values were 8.83 ± 0.48 and 8.81 ± 0.61 MPa·m1/2, respectively. 相似文献
992.
Joel Molina-Reyes Hugo Tiznado Gerardo Soto Monica Vargas-Bautista David Dominguez Eduardo Murillo Dan Sweeney John Read 《Journal of Materials Science: Materials in Electronics》2018,29(18):15349-15357
The physical, chemical, and electrical characteristics of intercalated nano-layers of Y2O3 and ZrO2, sequentially deposited by sputtering and thermal atomic-layer deposition (ALD), are reported in order to assess their use as electronic and/or ionic conductor. In general, the physical and chemical properties of sputtered and ALD-YSZ show good characteristics while a relatively high dielectric constant of about 30, along with a large capacitance–voltage hysteresis, are obtained for ALD-YSZ. Additionally, using inert or reactive metals as gate electrodes on YSZ/n-Si structures, promotes a change in the conduction of electronic and ionic species of YSZ and their influence is also reported. 相似文献
993.
Joel Penney 《The Journal of communication》2017,67(3):402-423
Drawing on interviews with leaders of the effort to promote the 2016 Bernie Sanders U.S. presidential candidacy on social media, this study contrasts the structure and content of various organizational networks to map the hybrid ecosystem of the contemporary digital campaign. While the “official” Sanders organization built applications to transform supporters into a tightly controlled distribution network for its social media messaging, this was complemented by “unofficial” grassroots networks that circulated more informal and culturally oriented appeals. The latter are classified according to the models of organizationally enabled and self-organized connective action in digital social movements, with structural differences in oversight and moderation that suggest varying levels of creative autonomy for citizens and reputational risk for the associated campaigns. 相似文献
994.
Louis King Daniel King Abdelmalek Bouazza Joel Gniel R. Kerry Rowe 《Geotextiles and Geomembranes》2021,49(1):159-165
Geosynthetic reinforced column supported embankments predominantly utilise two mechanisms to transfer embankment loads towards column heads, soil arching and membrane actions. When undertaking the design of column supported embankments, it is common practice to perform a two-step design, whereby the arching actions are estimated independently of the subsoil deformation and membrane actions. This approach is unable to capture the deformation dependency exhibited by both arching and membrane actions. This paper presents deformation dependent arching and membrane action models and implements them within an interaction diagram. It is shown that an interaction diagram-based design approach is capable of performing an ultimate and serviceability limit state design of a geosynthetic reinforced column supported embankment. In contrast, most existing analytical design methods only consider the ultimate limit state. The proposed method is applied to a design example where the benefits of such a design approach are demonstrated. 相似文献
995.
Wireless Personal Communications - VANETs are wireless sensor networks that suffer from the drawback of highly mobile nodes. The main objective of any type of network is to achieve efficient... 相似文献
996.
Joel P. Werren Lukas J. Troxler Oluwaseun Rume-Abiola Oyewole Alban Ramette Silvio D. Brugger Rmy Bruggmann Mark van der Linden Moon H. Nahm Ilche Gjuroski Carlo Casanova Julien Furrer Markus Hilty 《International journal of molecular sciences》2021,22(9)
The structure of the exopolysaccharide capsule of Streptococcus pneumoniae is defined by the genetic arrangement of the capsule operon allowing the unequivocal identification of the pneumococcal serotype. Here, we investigated the environment-dependent composition of the polysaccharide structure of S. pneumoniae serotype 6F. When grown in a chemically defined medium (CDM) with glucose versus galactose, the exopolysaccharide capsule of the serotype 6F strains reveals a ratio of 1/0.6 or 1/0.3 for galactose/glucose in the capsule by 1H-NMR analyses, respectively. Increased production of the capsule precursor UDP-glucose has been identified by 31P-NMR in CDM with glucose. Flow cytometric experiments using monoclonal antibodies showed decreased labelling of Hyp6AG4 (specific for serotype 6A) antibodies when 6F is grown in glucose as compared to galactose, which mirrors the 1H-NMR results. Whole-genome sequencing analyses of serotype 6F isolates suggested that the isolates evolved during two different events from serotype 6A during the time when the 13-valent pneumococcal conjugate vaccine (PCV-13) was introduced. In conclusion, this study shows differences in the capsular structure of serotype 6F strains using glucose as compared to galactose as the carbon source. Therefore, 6F strains may show slightly different polysaccharide composition while colonizing the human nasopharynx (galactose rich) as compared to invasive locations such as the blood (glucose rich). 相似文献
997.
In an effort to challenge the dominance of vision over the other senses in architectural experience, Joel Sanders and Karen Van Lengen infuse a speculative domestic environment with digital audio technology. Their design capitalises on the augmentation of aural–visual boundaries via technological interventions, ultimately recasting the house from a private and insulated environment to that of a hybridised interactive site. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
998.
Joel TURCHI 《电子产品世界》2004,(11):48-50
临界导电模式(BCM)目前是满足中低功率应用中功率因数校正(PFC)稳压的最常用方案.但是,这种解决方案的开关频率的方差很大,使得在噪声敏感和大功率范围应用中实现BCM电路很困难.为了克服这个缺点,安森美半导体开发了一个创新的功率因数控制器-NCP1601,可以在固定频率和不连续导电模式(DCM)中工作.为了达到整功率因数,电路根据在先前开关周期中测得的死区时间长度调制功率开关导电时间.本文讲述NCP1601方案和功能. 相似文献
999.
Improvement of soft soils using geogrid encased stone columns 总被引:2,自引:0,他引:2
In recent years, geotextile encasement has been used to extend the use of stone columns to extremely soft soils. Although the technique is now well established, little research has been undertaken on the use of other encasement materials such as geogrid. This paper discusses the results of a series of small-scale model column tests that were undertaken to investigate the behaviour of geogrid encased columns. The tests focused on studying the effect of varying the length of encasement and investigating whether a column that was partially encased with geogrid would behave similarly to a fully-encased column. In addition, isolated column behaviour was compared to group column behaviour. The results of partially encased column tests indicated a steady reduction in vertical strain with increasing encased length for both isolated columns and group columns. Bulging of the column was observed to occur directly beneath the base of the encasement. A significant increase in column stiffness and further reduction in column strain was observed for fully-encased columns, with strain reductions in the order of 80%. This range of performance may lend the techniques of partial and full geogrid encasement to a series of potential site applications. 相似文献
1000.
A simple scheme for the estimation of average thermo-physical properties has been presented. Properties such as thermal conductivity and specific heat have been calculated at suitable temperatures, which are functions of the ambient and the adiabatic flame temperatures. These have been successfully employed in the empirical correlations available in standard combustion text books for the estimation of burning rate constants and flame stand-off distances in the combustion of liquid and solid fuels. The average thermal conductivity is estimated as the thermal conductivity of standard air calculated at a temperature given as one-third of the sum of ambient and the adiabatic flame temperatures. The average specific heat is calculated as the specific heat of standard air at the adiabatic flame temperature itself. Extensive validation of the scheme with the experimental data is presented employing several liquid fuels and a solid fuel. 相似文献