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排序方式: 共有6949条查询结果,搜索用时 15 毫秒
61.
62.
B. S. Lee T. L. Yoon R. Abd-Shukor 《Journal of Superconductivity and Novel Magnetism》2017,30(12):3377-3395
The transition mechanism in high temperature cuprate superconductors is an outstanding puzzle. A previous suggestion on the role of non-linear local lattice instability modes on the microscopic pairing mechanism in high temperature cuprate superconductors (Lee, J. Supercond. Nov. Magn. 23(3), 333; 2009) is re-examined to provide a viable mechanism for superconductivity in these cuprates via an unusual lattice vibration in which an electron is predominantly interacting with a non-linear Q 2 mode of the oxygen clusters in the CuO2 planes. It is shown that the interaction has explicit d-wave symmetry and leads to an indirect coupling of d-wave symmetry between electrons. As a follow-up of Lee (J. Supercond. Nov. Magn. 23(3), 333; 2009), in this paper, we report detailed derivation of the superconducting gap equation and numerical solutions for the transition temperature as inherently integrated into the so-called extended Hubbard model (EHM). A unique feature in the EHM is that the transition temperature has an inherent k-dependence. In addition, superconducting gap solutions are restrained to specific regions in the first Brillouin zone (1BZ). It is very feasible to expect that the EHM naturally inherits a huge parameter space in which experimentally measured results, such as the well-known superconducting dome and the phase diagram from electronic Raman scattering (Sacuto et al., Rep. Prog. Phys. 76(2), 022502; 2013) can be accommodated. The EHM model hence offers a viable venue to search for or confirm any signature in k-point-sensitive experimental measurements. 相似文献
63.
64.
Enhancing Interfacial Bonding between Anisotropically Oriented Grains Using a Glue‐Nanofiller for Advanced Li‐Ion Battery Cathode 下载免费PDF全文
65.
Sang-Min Lee Jeong-Won Yoon Seung-Boo Jung 《Journal of Materials Science: Materials in Electronics》2016,27(2):1105-1112
The electromigration behavior of low-melting temperature Sn-58Bi (in wt%) solder joints was investigated with a high current density between 3 and 4.5 × 103 A/cm2 between 80 and 110 °C. In order to analyze the impact of various substrate metallizations on the electromigration performance of the Sn-58Bi joint, we used representative substrate metallizations including electroless nickel immersion gold (ENIG), electroless nickel electroless palladium immersion gold (ENEPIG), and organic solderability preservatives (OSP). As the applied current density increased, the time to failure (TTF) for electromigration decreased regardless of the temperature or substrate metallizations. In addition, the TTF slightly decreased with increasing temperature. The substrate metallization significantly affected the TTF for the electromigration behavior of the Sn-58Bi solder joints. The substrate metallizations for electromigration performance of the Sn-58Bi solder are ranked in the following order: OSP-Cu, ENEPIG, and ENIG. Due to the polarity effect, current stressing enhanced the fast growth of intermetallic compounds (IMCs) at the anode interface. Cracks occurred at the Ni3Sn4 + Ni3P IMC/Cu interfaces on the cathode sides in the Sn-58Bi/ENIG joint and the Sn-58Bi/ENEPIG joint; this was caused by the complete consumption of the Ni(P) layer. Alternatively, failure occurred via deformation of the bulk solder in the Sn-58Bi/OSP-Cu joint. The experimental results confirmed that the electromigration reliability of the Sn-58Bi/OSP-Cu joint was superior to those of the Sn-58Bi/ENIG or Sn-58Bi/ENEPIG joints. 相似文献
66.
67.
Kien Tiek Wong Boris Brigljević Jeong Hyeon Lee So Yeon Yoon Seok Byum Jang Choe Earn Choong Inwook Nah Hyeongjun Kim Hyun-Seog Roh Sang Kyu Kwak Hankwon Lim Min Jang 《Small (Weinheim an der Bergstrasse, Germany)》2023,19(1):2204336
This study focuses on the applicability of single-atom Mo-doped graphitic carbon nitride (GCN) nanosheets which are specifically engineered with high surface area (exfoliated GCN), NH2 rich edges, and maximum utilization of isolated atomic Mo for propylene carbonate (PC) production through CO2 cycloaddition of propylene oxide (PO). Various operational parameters are optimized, for example, temperature (130 °C), pressure (20 bar), catalyst (Mo2GCN), and catalyst mass (0.1 g). Under optimal conditions, 2% Mo-doped GCN (Mo2GCN) has the highest catalytic performance, especially the turnover frequency (TOF) obtained, 36.4 h−1 is higher than most reported studies. DFT simulations prove the catalytic performance of Mo2GCN significantly decreases the activation energy barrier for PO ring-opening from 50–60 to 4.903 kcal mol−1. Coexistence of Lewis acid/base group improves the CO2 cycloaddition performance by the formation of coordination bond between electron-deficient Mo atom with O atom of PO, while NH2 surface group disrupts the stability of CO2 bond by donating electrons into its low-level empty orbital. Steady-state process simulation of the industrial-scale consumes 4.4 ton h−1 of CO2 with PC production of 10.2 ton h−1. Techno-economic assessment profit from Mo2GCN is estimated to be 60.39 million USD year−1 at a catalyst loss rate of 0.01 wt% h−1. 相似文献
68.
Bong Seok Park Jin Bae Park Yoon Ho Choi 《International Journal of Control, Automation and Systems》2011,9(3):534-541
In this paper, an adaptive observer-based trajectory tracking problem is solved for nonholonomic mobile robots with uncertainties.
An adaptive observer is first developed to estimate the unmeasured velocities of a mobile robot with model uncertainties.
Using the designed observer and the backstepping technique, a trajectory tracking controller is designed to generate the torque
as an input. Using Lyapunov stability analysis, we prove that the closed-loop system is asymptotically stable with respect
to the estimation errors and tracking errors. Finally, the simulation results are presented to validate the performance and
robustness of the proposed control system against uncertainties. 相似文献
69.
We analyze characteristics and patterns of color juxtaposition and the color theory used by pointillist painters and employ them to create rendering algorithm that generates images in a pointillist style. We determine the distribution of colors in several paintings by Seurat and quantify a number of the theory that he employs. Using an RYB color wheel and a hierarchical point generation technique, we convert an input image into a set of colored dots, which is again converted into brush strokes with appropriate shapes and directions. We present images which illustrate the extent to which we have managed to simulate Seurat’s technique. 相似文献
70.
Tomoko Watanabe Traphagan Yueh-hui Vanessa Chiang Hyeseung Maria Chang Benjaporn Wattanawaha Haekyung Lee Michael Charles Mayrath Jeongwon Woo Hyo-Jin Yoon Min Jung Jee Paul E. Resta 《Computers & Education》2010
Using a framework of cognitive, social, and teaching presence, the nature of learning experiences in a three-dimensional virtual world environment (Second Life) and a text-chat learning environment without visuals (TeachNet) were investigated. A mixed method of code frequencies, coherence graphs, interviews, and a survey was used. The results revealed that the TeachNet debates included more cognitive presence codes that indicate higher levels of cognitive processing than in SL debates. The teams were significantly different from each other in the collaboration style for developing arguments and in the ways to use utterances associated with cognitive, social, and teaching presences, and the groups’ collaboration style became more established with more experience with the tasks. The three critical factors–tool, tasks and group cohesion–that affect cognitive, teaching, and social presence are discussed. 相似文献