Quantization of the Interior Schwarzschild Black Hole

We study a Hamiltonian quantum formalism of a spherically symmetric space-time which can be identified with the interior of a Schwarzschild black hole. The phase space of this model is spanned by two dynamical variables and their conjugate momenta. It is shown that the classical Lagrangian of the model gives rise the interior metric of a Schwarzschild black hole. We also show that the mass of such a system is a Dirac observable and then by quantization of the model by Wheeler-DeWitt approach and constructing suitable wave packets we get the mass spectrum of the black hole.     

Shaft crack diagnostics in a gearbox

Shaft breakage is one of the most catastrophic failures in any transmission system that can ultimately lead to significant financial loss. Although advances in shaft design have lead to improvements in endurance life, shaft failures are still common today. This paper presents an experimental investigation in which several technologies such as Acoustic Emission, vibration and motor current signature analysis, were applied to identify the presence of a naturally fatigued pinion shaft in an operating gearbox. It was concluded that the combination of these methods could offer good diagnostic information though successful diagnosis is very dependent on the diagnostic path taken by the investigator.     

Computational study of a supersonic free jet rotating perpendicular to the streamwise direction

We study the flow structure of supersonic jets rotating perpendicular to the streamwise direction using RANS simulations, and we assess the performance of different turbulence model rotation corrections. The Coriolis and centrifugal terms were added to the equations of motion to perform calculations in this non-inertial (rotating) frame of reference. An explicit, cell-centred, finite-volume numerical method, coupled to a k?ε turbulence model, was used for the computations. The turbulence model rotation corrections of Howard et al. (1980), Park and Chung (1999), and Cazalbou et al. (2005) were attempted. In the absence of experimental data for jets rotating perpendicular to the streamwise direction, the rotation corrections were examined against the available measurements of a swirling jet; the comparison of the numerical and experimental data indicates that the Cazalbou et al. (2005 Cazalbou, J.B. 2005. Two-equation modeling of turbulent rotating flows. Physics of Fluids, 17(5): 1–14. [Crossref], [Web of Science ®] , [Google Scholar]) and Park and Chung (1999 Park, J.Y. and Chung, M.K. 1999. A model for the decay of rotating homogeneous turbulence. Physics of Fluids, 11(6): 1544–1549. [Crossref], [Web of Science ®] , [Google Scholar]) corrections improve the performace of the turbulence model. Simulations were then run of a supersonic jet rotating perpendicular to the stream direction at 0, 50, 100 and 150 rad/s, using no turbulence model rotation correction, and using the three rotation corrections. The results indicate that the Cazalbou et al. (2005 Cazalbou, J.B. 2005. Two-equation modeling of turbulent rotating flows. Physics of Fluids, 17(5): 1–14. [Crossref], [Web of Science ®] , [Google Scholar]) correction is more physical than the other two, as it yields results that are qualitatively consistent with the known effects of rotation: that turbulence is enhanced and suppressed on the concave and convex sides of a rotating jet centreline, respectively, and that the effect of rotation saturates as the rotation rate increases. The findings are in qualitative agreement with the available literature.     

Thixotropy, yielding and ultrasonic Doppler velocimetry in pulp fibre suspensions

This paper reports thixotropy in concentrated pulp fibre suspensions and studies their transient flow behaviour using conventional rheometry coupled with a velocimetry technique. Specifically, an ultrasonic Doppler velocimeter is used in conjunction with a rate-controlled rheometer to deduce the local velocity profiles of pulp fibre suspensions. Pulp suspensions are found to exhibit a plateau in their flow curves where a slight increase in the shear stress generates a jump in the corresponding shear rate, implying the occurrence of shear banding. The velocity profiles were found to be discontinuous in the vicinity of the yielding radius where the Herschel–Bulkley model failed to predict the flow. Shear history and the time of rest prior to the measurement were found to play a significant role on the rheology and the local velocity profiles of pulp suspensions.     

A Novel Polymeric Lead(II)‐Azido Compound: Synthesis,Structural Characterization,and DFT Calculations of [Pb(dmp)(N3)2]n

A novel 1D Pb^II coordination polymer containing Pb₂‐(μ‐N₃)₂ unit [Pb(dmp)(N₃)₂]_n (dmp =  2,9‐dimethyl‐1,10‐phenanthroline) has been prepared and characterized. Single‐crystal X‐ray diffraction analyses show that the coordination number for Pb^II ions is six, PbN₆, with “stereochemically active” electron lone pairs and the coordination sphere being hemidirected. The single‐crystal X‐ray data show the chains interact with each other through the π–π stacking interactions, which create a 3D framework. The structure of title complex has been optimized by density functional theory. Structural parameters and IR spectra for the complex are in agreement with the crystal structure.     

Modeling first bid in retail secondary market online auctions: A Bayesian approach

We propose a Bayesian framework to model bid placement time in retail secondary market online business‐to‐business auctions. In doing so, we propose a Bayesian beta regression model to predict the first bidder and time to first bid, and a dynamic probit model to analyze participation. In our development, we consider both auction‐specific and bidder‐specific explanatory variables. While we primarily focus on the predictive performance of the models, we also discuss how auction features and bidders' heterogeneity could affect the bid timings, as well as auction participation. We illustrate the implementation of our models by applying to actual auction data and discuss additional insights provided by the Bayesian approach, which can benefit auctioneers.     

Selecting most efficient information system projects in presence of user subjective opinions: a DEA approach

Information System (IS) project selection is a critical decision making task that can significantly impact operational excellence and competitive advantage of modern enterprises and also can involve them in a long-term commitment. This decision making is complicated due to availability of numerous IS projects, their increasing complexities, importance of timely decisions in a dynamic environment, as well as existence of multiple qualitative and quantitative criteria. This paper proposes a Data Envelopment Analysis approach to find most efficient IS projects while considering subjective opinions and intuitive senses of decision makers. The proposed approach is validated by a real world case study involving 41 IS projects at a large financial institution as well as 18 artificial projects which are defined by the decision makers.     

Kinetics and thermodynamics of adsorption of congo red on cellulose

Thermodynamics and kinetics of adsorption of congo red (CR) on cellulose are studied at 308–328 K. In the used concentration range of CR, interaction of CR with cellulose is exothermic and CR molecules adsorb chemically on cellulose surface. The effects of contact time, temperature and initial concentration of CR on kinetics of its adsorption on cellulose were investigated. The process proceeds according to the pseudo-second-order equation. Initial adsorption rate of adsorption is first-order in CR and the intraparticle diffusion of CR molecules within cellulose is identified as the main rate-limiting step.      

Total Synthesis of (−)‐Salinosporamide A via a Late Stage C−H Insertion

The synthesis of (?)‐salinosporamide A, a proteasome inhibitor, is described. The synthesis highlights the assembly of a densely decorated pyrrolidinone core via an aza‐Payne/hydroamination sequence. Central to the success of the synthesis is a late‐stage C?H insertion reaction to functionalize a sterically encumbered secondary carbon. The latter functionalization leads to an enabling transformation where most of the prototypical strategies failed.