33,045 research outputs found
q-Differential equations for q-classical polynomials and q-Jacobi-Stirling numbers
No full textWe introduce, characterise and provide a combinatorial interpretation for the so-called q-Jacobi–Stirling numbers.
This study is motivated by their key role in the (reciprocal) expansion of any power of a second order
q-differential operator having the q-classical polynomials as eigenfunctions in terms of other even order operators,
which we explicitly construct in this work. The results here obtained can be viewed as the q-version of
those given by Everitt et al. and by the first author, whilst the combinatorics of this new set of numbers is a
q-version of the Jacobi–Stirling numbers given by Gelineau and the second author
Investigation of transition between spark ignition and controlled auto-ignition combustion in a V6 direct-injection engine with cam profile switching
No full textControlled auto-ignition (CAI) combustion, also known as Homogeneous Charge Compression Ignition (HCCI) can be achieved by trapping residuals with early exhaust valve closure in a direct fuel injection in-cylinder four-stroke gasoline engines (through the employment of low-lift cam profiles). Due to the operating region being limited to low and mid-load operation for CAI combustion with a low-lift cam profile, it is important to be able to operate SI combustion at high-load with a normal cam profile. A 3.0L prototype engine was modified to achieve CAI combustion, using a Cam Profile Switching mechanism which has the capability to switch between high and low-lift cam-profiles. A strategy was used where a high-profile could be used for SI combustion and a low-lift profile was used for CAI combustion. Initial analysis showed that for transitioning from SI to CAI combustion, misfire occurred on the first CAI transitional cycle. Subsequent experiments showed that the throttle opening position and switching time could be controlled avoiding misfire. Further work investigated transitioning at different loads and from CAI to SI combustion
Direct numerical simulation of weakly spanwise-rotating turbulent plane Couette flow
No full textIn this report, we conduct direct numerical simulations (DNS) of weakly spanwise-rotating plane Couette flows at Reynolds number (here, is the half the wall velocity difference, and is half-channel height). A series of simulations with different rotation numbers ( is constant angular velocity component in the spanwise direction) is carried out to investigate the effect of on the flow statistics. Our results show that the flow statistics are affected by the , and a "critical" rotation number (between and ) is observed, where the kinetic energy of secondary flow contributes about a half of the turbulent kinetic energy, and the mean shear rate at the center line reaches a minimum value. We conjecture that different mechanisms should exist around , and will be investigated further
INNOVATIVE PILLAR[6]ARENE-BASED STATIONARY PHASES FOR HIGH-RESOLUTION GAS CHROMATOGRAPHIC ANALYSES
No full textIn this work, the synthesis, fabrication, and characterization of new stationary phases based on pillar[6]arene derivative modified by long alkyl chains (P6A-C10) for high-resolution gas chromatographic (GC) analyses are reported. Pillar[n]arenes are a new class of macrocyclic hosts that can accommodate specific guests due to their highly symmetrical and rigid pillar architectures with π-electron rich cavities. Quantum chemistry calculations have been performed, showing a difference in non-covalent interactions with the P6A-C10 pillar framework, which leads to specific selectivity for aromatic compounds. The GC columns prepared with these innovative stationary phases exhibited a medium polarity, and good reproducibility for run-to-run, day-to-day, and column-to-column analyses [1], demonstrating great potential as new stationary phases in separation science. Furthermore, peculiar advantages are achieved if compared with the commercial HP-5, HP-35, DB-17, and PEG-20M columns, showing unmatched resolving capabilities toward chloroaniline, bromoaniline, iodoaniline, toluidine, and xylene isomers [2].
References:
1. Sun, T., Chen, R., Huang, Q., Ba, M., Cai, Z., Hu, S., Liu, X., Nardiello, D., & Quinto, M., ACS Appl. Mater. Interfaces 14 (2022) 56132−56142.
2. Sun, T., Chen, R., Huang, Q., Ba, M., Cai, Z., Chen, H., Qi, Y., Chen, H., Liu, X., Nardiello, D., & Quinto, M., Anal. Chim. Acta 1251 (2023) 340979
Знахідка Didymella glomerata (Corda) Q. Chen & L. Cai з території запроектованого НПП “Ізюмська Лука”
No full textInformation about the new find of Didymella glomerata (Corda) Q. Chen & L. Cai (Didymellaceae, Pleosporales, Ascomycota, Fungi), confirmed by ITS and LSU DNA sequences, are given
Special adsorption behaviour of boron nitride nanosheets for improved sensing
No full textQiran Cai has been focusing on the research of Boron Nitride Nanosheets for Improved Sensing. He is a productive student, since he published five first-author papers and two of which are high impact factor over 10. In addition, he also involved another five co-author high impact papers.<br
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