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991.
992.
S.-H. Park 《国际生产研究杂志》2013,51(17):4751-4767
This paper focuses on sequencing welding lines in multiple arc-welding robot systems, which is the problem of assigning individual welding operations to robots as well as determining their sequences with the objective of minimizing the maximum completion time. Each welding operation is denoted by a weld line with two end-points, each of which can be a possible starting point for the welding operation. Thermal distortion is explicitly considered by introducing a delay between welding operations associated with weld lines near each other. Due to the complexity of the problem, this paper suggests three types of search heuristics, genetic algorithms, simulated annealing and tabu search, each of which incorporates new methods to generate neighbourhood solutions. To show the performances of the heuristics, computational experiments are performed on a number of randomly generated test problems, and the results are reported. In particular, some of the search heuristics outperform the exiting method. 相似文献
993.
994.
In this study, we demonstrate an atomic force microscopy process for manipulating multiferroic BiFeO3 nanodots smaller than 15 nm to desired positions on a Nb‐doped SrTiO3 substrate. For formation of the BiFeO3 nanodot array, nanocrystal movement was achieved using a +1.2 V biased conducting atomic force microscopy (CAFM) followed by nanocrystal attachment to the tip. Using this method, high‐density BiFeO3 nanodot arrays with a density greater than 0.5 Tb/in.2 can be achieved. Perfectly flipped ferroelectric polarization with an external electric field was observed for each BiFeO3 nanodot, whose ferroelectric properties were confirmed using piezoelectric force microscopy. 相似文献
995.
996.
G. Mohan Kumar P. Ilanchezhiyan Jin Kawakita Jinsub Park R. Jayavel 《Journal of Materials Science: Materials in Electronics》2013,24(8):2989-2994
One-dimensional Mn doped ZnO nanocrystallites were synthesized through a facile low temperature surfactant free chemical route. The crystallite structure and morphological evolution of the particles were revealed to be of wurtzite phase and rod like structures from the X-ray diffraction and transmission electron microscopic analysis, respectively. Using Raman spectroscopy the role of oxygen related defects and phase purity in the Mn substituted ZnO systems were studied systematically. A significant suppression in the sub-band edge emission was visualized in the room temperature emission spectra of the Mn doped systems. The intensity ratio in between the near-band edge and defect-level emissions was observed to increase, signifying the reduction in oxygen related defects and revealing their influence on the crystallinity on the Mn substituted ZnO species. These variations were correlated with the increasing number of Mn ions in the host lattice, which results with their passivating action on the surface defects. 相似文献
997.
Chanhoon Kim Gaeun Hwang Ji-Won Jung Su-Ho Cho Jun Young Cheong Sunghee Shin Soojin Park Il-Doo Kim 《Advanced functional materials》2017,27(14):1605975
Nanostructuring has significantly contributed to alleviating the huge volume expansion problem of the Ge anodes. However, the practical use of nanostructured Ge anodes has been hindered due to several problems including a low tap density, poor scalability, and severe side reactions. Therefore, micrometer-sized Ge is desirable for practical use of Ge-based anode materials. Here, micronized Ge3N4 with a high tap density of 1.1 mg cm−2 has been successfully developed via a scalable wet oxidation and a subsequent nitridation process of commercially available micrometer-sized Ge as the starting material. The micronized Ge3N4 shows much-suppressed volume expansion compared to micrometer-sized Ge. After the carbon coating process, a thin carbon layer (≈3 nm) is uniformly coated on the micronized Ge3N4, which significantly improves electrical conductivity. As a result, micronized Ge3N4@C shows high reversible capacity of 924 mAh g−1 (2.1 mAh cm−2) with high mass loading of 3.5 mg cm−2 and retains 91% of initial capacity after 300 cycles at a rate of 0.5 C. Additionally, the effectiveness of Ge3N4@C as practical anodes is comprehensively demonstrated for the full cell, showing stable cycle retention and especially excellent rate capability, retaining 47% of its initial capacity at 0.2 C for 12 min discharge/charge condition. 相似文献
998.
Byeung Jun Lim Tae Choon Park Sejin Kwon 《Journal of Mechanical Science and Technology》2014,28(9):3569-3581
Characteristic changes in the stall inception in a single-stage transonic axial compressor with an axial skewed slot casing treatment were investigated experimentally. A rotating stall occurred intermittently in a compressor with an axial skewed slot, whereas spike-type rotating stalls occurred in the case of smooth casing. The axial skewed slot suppressed stall cell growth and increased the operating range. A mild surge, the frequency of which is the Helmholtz frequency of the compressor system, occurred with the rotating stall. The irregularity in the pressure signals at the slot bottom increased decreasing flow rate. An autocorrelation-based stall warning method was applied to the measured pressure signals. Results estimate and warn against the stall margin in a compressor with an axial skewed slot. 相似文献
999.
Byung Hoon Jo Jaoon Y.H. Kim Jeong Hyun Seo Hyung Joon Cha 《International Journal of Hydrogen Energy》2014
H2 production under aerobic conditions has been proposed as an alternative method to overcome the fundamentally low yield of H2 production by fermentative bacteria by maximizing the number of electrons that are available for H2. Here, we engineered Vitreoscilla hemoglobin (VHb) in Escherichia coli to study the effects of this versatile oxygen (O2)-binding protein on oxic H2 production in a closed batch system that was supplemented with glucose. The H2 yields that were obtained with the VHb-expressing E. coli were greatly enhanced in comparison to the negative control cells in culture that started with high O2 tensions. The formate hydrogen lyase (FHL) activity of oxically cultured, VHb-expressing cells was also much higher than that of the negative control cells. Through inhibitor studies and time-course experiments, VHb was shown to contribute to the improved H2 yield primarily by increasing the efficiency of cellular metabolism during the aerobic phase before the onset of H2 production and not by working as an O2-scavenger during H2 production. This new approach allowed more substrate to remain to be further utilized for the production of more H2 from limited resources. We expect that VHb can be successfully engineered in potential aerobic H2-producing microbial systems to enhance the overall H2 production yield. In addition, the remarkably high FHL activity of oxically grown, VHb-expressing cells may make this engineered strain an attractive whole-cell biocatalyst for converting formate to H2. 相似文献
1000.
Jin-Seong Park 《Journal of Electroceramics》2012,28(1):74-79
The characteristics of amorphous In-Ga-Zn-O(IGZO) thin film transistors (TFTs) and load inverters with a short channel length
were studied. The IGZO TFTs showed a mobility value of > 5 cm2/Vs with a Vth value of -1.62 V. No degradation of the TFT properties, such as a negative shift of Vth or degradation of the subthreshold slope by the short-channel effect, were observed down to a channel length of 2 μm. A load
inverter using an IGZO TFT with a gate length of 2 μm and resistor of 1 MΩ was fabricated and characterized, and a voltage
gain of 4 was obtained at a VDD value of 10 V. Additionally, the action of a dynamic inverter operating at frequencies of 1 and 10 kHz was characterized.
Complete inverter action was obtained at 1 kHz, while an delay time of 0.53 μs was observed at 10 kHz. These promising results
indicate that short channel IGZO TFTs are candidate for TFTs in the display industry, including active-matrix organic light-emitting
diodes or multi-view three-dimension TV. 相似文献