17,986 research outputs found
Electro-optically Q-switched Er:YAG laser in-band pumped by an Er,Yb fiber laser
No full textElectro-optically Q-switched operation of an Er:YAG laser at 1645nm end-pumped by a cladding-pumped Er-Yb fiber laser is reported. Pulse energies up to 15mJ have been generated at a pulse repetition frequency of 29Hz
AFM and Proteomic Analysis of Spore Coat Related to Spore Germination of Geobacillus stearothermophilus
No full textDONG, W, SHEN, Q, AL ZAHARNA, M, ZHANG, Z & CHEUNG, HY 2013, 'AFM and Proteomic Analysis of Spore Coat Related to Spore Germination of Geobacillus stearothermophilus' Paper presented at 2nd International Conference on Medical, Biological and Pharmaceutical Sciences, London, United Kingdom, 17/06/13 - 18/06/13 … DONG, W., SHEN, Q., AL ZAHARNA, M., ZHANG, Z., & CHEUNG, HY (2013). AFM and Proteomic Analysis of Spore Coat Related to Spore Germination of Geobacillus stearothermophilus. Paper presented at 2nd International Conference on Medical, Biological and Pharmaceutical Sciences, London, United Kingdom. … DONG W, SHEN Q, AL ZAHARNA M, ZHANG Z, CHEUNG HY. AFM and Proteomic Analysis of Spore Coat Related to Spore Germination of Geobacillus stearothermophilus. 2013. Paper presented at 2nd International Conference on Medical, Biological and Pharmaceutical
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
-analogues of two supercongruences of Z.-W. Sun
No full textsummary:We give several different -analogues of the following two congruences of \hbox {Z.-W. Sun}: where is an odd prime, is a positive integer, and is the Jacobi symbol. The proofs of them require the use of some curious -series identities, two of which are related to Franklin's involution on partitions into distinct parts. We also confirm a conjecture of the latter author and Zeng in 2012
Exploring multi-stability in three-dimensional viscoelastic flow around a free stagnation point
No full textFluid elements passing near a stagnation point experience finite strain rates over long persistence times, and thus accumulate large strains. By the numerical optimization of a microfluidic 6-arm cross-slot geometry, recent works have harnessed this flow type as a tool for performing uniaxial and biaxial extensional rheometry (Haward et al., 2023 [5,6]). Here we use the microfluidic ‘Optimized-shape Uniaxial and Biaxial Extensional Rheometer’ (OUBER) geometry to probe an elastic flow instability which is sensitive to the alignment of the extensional flow. A three-dimensional symmetry-breaking instability occurring for flow of a dilute polymer solution in the OUBER geometry is studied experimentally by leveraging tomographic particle image velocimetry. Above a critical Weissenberg number, flow in uniaxial extension undergoes a supercritical pitchfork bifurcation to a multi-stable state. However, for biaxial extension (which is simply the kinematic inverse of uniaxial extension) the instability is strongly suppressed. In uniaxial extension, the multiple stable states align in an apparently random orientation as flow joining from four neighbouring inlet channels passes to one of the two opposing outlets; thus forming a mirrored asymmetry about the stagnation point. We relate the suppression of the instability in biaxial extension to the kinematic history of flow under the context of breaking the time-reversibility assumption
Microtomographic particle image velocimetry measurements of viscoelastic instabilities in a three-dimensional microcontraction
No full textViscoelastic flow through an abrupt planar contraction geometry above a certain Weissenberg number () is well known to become unstable upstream of the contraction plane via a central jet separating from the walls and forming vortices in the salient corners. Here, for the first time, we consider three-dimensional (3-D) viscoelastic contraction flows in a microfabricated glass square–square contraction geometry. We employ state-of-the-art microtomographic particle image velocimetry to produce time-resolved and volumetric quantification of the 3-D viscoelastic instabilities arising in a dilute polymer solution driven through the geometry over a wide range of but at negligible Reynolds number. Based on our observations, we describe new insights into the growth, propagation and transient dynamics of an elastic vortex formed upstream of the 3-D microcontraction due to flow jetting towards the contraction. At low we observe vortex growth for increasing , followed by a previously unreported vortex growth plateau region. In the plateau region, the vortex circulates around the jet with a period that decreases with but an amplitude that is independent of . In addition, we report new out-of-plane asymmetric jetting behaviour with a phase-wise dependence on . Finally, we resolve the rate-of-strain tensor and ascribe local gradients in as the underlying driver of circulation via strain hardening of the fluid in the wake of the jet
The Importance of Master Planned Communities for the Enhancement of Inhabitation Sustainability for Mix-Used Urban Neighbourhood
No full textHighly efficient in-band pumped Er:YAG laser with 60 W of output at 1645 nm
No full textA high-power Er:YAG laser that is in-band pumped by a high-power cladding-pumped erbium-ytterbium codoped fiber laser operating at 1532 nm is reported. The Er:YAG laser produced 60.3 W of continuous-wave output at 1645.3 nm in a beam with M<1.2 for 32.4 W of incident pump power. The slope efficiency with respect to incident pump power at pump powers of >20 W was ~81%. In the Q-switched mode of operation, a slightly modified resonator configuration incorporating an electro-optic Q switch produced pulses of ~4 mJ energy and ~100 ns (FWHM) duration, corresponding to a peak power of ~42 kW at a repetition rate of 1 kHz for an incident pump power of 16.8 W. The prospects for further improvement in continuous-wave and Q-switched performance are discussed
Sub-MHz Self-Q-switching in Nd:LuAG Laser
No full textA compact pulsed Nd:LuAG laser at 1064 nm based on the self-Q-switching technique is reported, having the output power as high as 6.61 W at the incident pump power of 21.32 W, corresponding to the optical conversion efficiency of ~31 %. The temporal width of the pulse was in the range from 532.2 ns to 652.6 ns, and the repetition rate varied between 488.6 kHz and 551.9 kHz. To the best of our knowledge, this is the first report on the self-Q-switching Nd:LuAG laser. Possible reasons for the self-Q-switching of Nd:LuAG were also provided, and the factor leading to the high repetition rate was analyzed. The compact cavity generating pulses with high output power and high repetition rate not only reveal that the self-Q-switching technique could be an efficient method for the generation of pulses with high output power and high repetition rate, but enrich the characteristics of Nd:LuAG crystal
Tobin's Q and Financial Policy
No full textRecent research in macroeconomics has emphasized the importance of linking the financial and real sectors and the need for working with optimizing models. Tobin’s Q model of investment would appear to provide a framework that can satisfy these two criteria. In contrast to the original presentation of the Q model, the formal development has not recognized that the firm actively participates in a number of financial markets; in this broader context, we show that Q is likely to be an uninformative and possibly misleading signal for investment expenditures . We then endeavor to turn this negative theoretical result to positive advantage in resolving a number of empirical problems with Q models, but the modifications dictated by the theory receive little support from the data.
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