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排序方式: 共有624条查询结果,搜索用时 15 毫秒
41.
42.
In parameterized string matching the pattern P matches a substring t of the text T if there exist a bijective mapping from the symbols of P to the symbols of t. We give simple and practical algorithms for finding all such pattern occurrences in sublinear time on average. The algorithms work for a single and multiple patterns. 相似文献
43.
High Open‐Circuit Voltages in Tin‐Rich Low‐Bandgap Perovskite‐Based Planar Heterojunction Photovoltaics 下载免费PDF全文
44.
Xian Yang Yu Zhang Xuejie Zhang Jian Chen Haisen Huang Dongsheng Wang Xirong Chai Gening Xie Maxim S. Molokeev Haoran Zhang Yingliang Liu Bingfu Lei 《Journal of the American Ceramic Society》2020,103(3):1773-1781
The red emission with suitable peak wavelength and narrow band is acutely required for high color rendering index (CRI) white LEDs without at the cost of the luminous efficacy. Herein, the Li2Ca2Mg2Si2N6:Eu2+ red phosphor was prepared with facile solid-state method using Ca3N2, Mg3N2, Si3N4, Li3N, and Eu2O3 as the safety raw materials under atmospheric pressure for the first time, which shows red emission peaking at 638 nm with full width at half maximum (FWHM) of 62 nm under blue light irradiation and becomes the desired red phosphor to realize the balance between luminous efficacy and high CRI in white LEDs. The morphology, structure, luminescence properties, thermal quenching behavior, and chromaticity stability of the Li2Ca2Mg2Si2N6:Eu2+ phosphor are investigated in detail. Concentration quenching occurs when the Eu2+ content exceeds 1.0 mol%, whereas high-temperature photoluminescent measurements show a 32% drop from the room-temperature efficiency at 423 K. In view of the excellent luminescence performances of Li2Ca2Mg2Si2N6:Eu2+ phosphor, a white LEDs with CRI of 91 as a proof-of-concept experiment was fabricated by coating the title phosphor with Y3Al5O12:Ce3+ on a blue LED chip. In addition, the potential application of the title phosphor in plant growth LED device was also demonstrated. All the results indicate that Li2Ca2Mg2Si2N6:Eu2+ is a promising red-emitting phosphor for blue LED-based high CRI white LEDs and plant growth lighting sources. 相似文献
45.
Sergei V. Kalinin Brian J. Rodriguez Albina Y. Borisevich Arthur P. Baddorf Nina Balke Hye Jung Chang Long‐Qing Chen Samrat Choudhury Stephen Jesse Peter Maksymovych Maxim P. Nikiforov Stephen J. Pennycook 《Advanced materials (Deerfield Beach, Fla.)》2010,22(3):314-322
The plethora of lattice and electronic behaviors in ferroelectric and multiferroic materials and heterostructures opens vistas into novel physical phenomena including magnetoelectric coupling and ferroelectric tunneling. The development of new classes of electronic, energy‐storage, and information‐technology devices depends critically on understanding and controlling field‐induced polarization switching. Polarization reversal is controlled by defects that determine activation energy, critical switching bias, and the selection between thermodynamically equivalent polarization states in multiaxial ferroelectrics. Understanding and controlling defect functionality in ferroelectric materials is as critical to the future of oxide electronics and solid‐state electrochemistry as defects in semiconductors are for semiconductor electronics. Here, recent advances in understanding the defect‐mediated switching mechanisms, enabled by recent advances in electron and scanning probe microscopy, are discussed. The synergy between local probes and structural methods offers a pathway to decipher deterministic polarization switching mechanisms on the level of a single atomically defined defect. 相似文献
46.
Ilham Zainal Abidin Catalin Mandache Gui Yun Tian Maxim Morozov 《NDT & E International》2009,42(7):599-605
In pulsed eddy current testing, repetitive excitation signals with different duty cycles have different spectral representations. This work studies the influence of duty cycle on the ability to detect holes and EDM notches beneath rivet heads in subsurface layers of stratified samples. Feature patterns for the integrity of rivet joints are proposed and verified. The proposed method has the added advantage in that no reference sample is needed while employing multiple pulse measurements, with different pulse widths. Experimental testing and modelling approaches are discussed in connection with defect depth quantification, which can be extended to the quantification of complex defects. 相似文献
47.
A detailed investigation into the isolation by extraction and the purification by crystallization of the enzyme urease from jack bean meal is presented with a view to developing a large-scale process. The effect of different extraction solvents and additives upon the resulting crystals is characterised in terms of crystal size, protein yield and protein purity. The enzymatic activity of urease is exploited in order to quantify the amount and purity of the protein obtained. The extraction procedure was optimised and all stages of the process were monitored in order to provide as detailed a picture as possible of the impact of different process stages upon the intermediate products. Almost all protein is extracted in a single extraction step. Further extraction steps using the same meal but fresh solvent yield only small additional protein yields. Less than 10% of total protein is extracted in a second step, less than 3% in a third extraction. Different solvents lead to clear differences in product quality, with no single solvent optimising all quality criteria. In addition, the point at which the acetone precipitant is introduced into the process has a clear influence on the product. Judicious choice of extraction conditions can significantly increase the size of the urease crystals at the cost of product purity, quantified by specific activity. High product purity (a maximum 138-fold increase in purity was observed with a maximum yield of 8.4%), in contrast, leads to smaller crystals. Comparison to the purest commercially available urease revealed a similar urease content. 相似文献
48.
This work was supported by a grant from ASM International. Literature searched through 1988. Part of the bibliographic search
was provided by ASM International. Professor Alcock and Dr. Itkin are the ASM/NIST Data Program Co-Category Editors for binary
alkaline earth alloys. 相似文献
49.
Maxim Ouellet 《Urban Water Journal》2018,15(4):392-397
Statistical models that predict the deterioration of sewer pipes are useful for planning financial resources required for sewer renewal. Usually, data that are available to calibrate these models solely concern pipes that are still in place, leading to underestimated deterioration rates. A new method is proposed to consider possible past replacement of pipes in the statistical modeling of their deterioration. The proposed method considers the aging of pipes, simulated with a Cox model, and their probability to be replaced separately. Application to a synthetic sewer network, for which it was assumed that information regarding all pipe replacements over the lifetime of the network was available, showed that the proposed method allows for improved predictions of the sewer deterioration model, when compared to predictions of a model calibrated without considering the information about replaced pipes. 相似文献
50.
Synthesis and gas permeation parameters of metathesis polytricyclononenes with pendant Me3E‐groups (E = C,Si, Ge) 下载免费PDF全文
Maxim Bermeshev Boris Bulgakov Lyudmila Starannikova Georgii Dibrov Pavel Chapala Dmitry Demchuk Yurii Yampolskii Eugene Finkelshtein 《应用聚合物科学杂志》2015,132(5)
Metathesis polytricyclononenes were synthesized via ROMP polymerization in the presence of the 1‐st generation Grubbs catalyst and their gas‐transport properties were studied for the first time. The aim of this work was to evaluate the influence of Me3E‐groups (E = C, Si, Ge) on gas permeation parameters of ROMP materials. New metathesis poly(3‐tert‐butyltricyclononene‐7) and poly(3‐trimethylgermyltricyclononene‐7) were obtained with high yields (up to 95%) and high‐molecular weights (Mw~3–7×105 g mol?1). The glass transition temperatures of the ROMP polytricyclononenes with Me3E‐groups decreased when E was changed from C to Si and then to Ge. It was shown that the polytricyclononene containing Me3Si‐groups has the highest gas permeability while the polytricyclononene containing Me3C‐substituents has the lowest gas permeability. In addition, the gas permeation parameters were estimated for ROMP Me3Si‐ and Me3Ge‐substituted polytricyclonona‐3,7‐dienes. So the influence of the second double bond in the monomer units on the permeability of the polymers obtained was studied. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41395. 相似文献