7,003 research outputs found
Pressure Drop in Capsule Transporting Bends Carrying Spherical Capsules
No full textOne of the most important parameters in designing a capsule transporting pipeline is the pressure drop in the pipes carrying capsules and associated pipe fittings such as bends etc. Capsules are hollow containers with typically cylindrical or spherical shapes flowing in the pipeline along with the carrier fluid. The dynamic behavior of a long train of capsules depends on the behavior of each capsule in the train and the hydrodynamic influence of one capsule on another. Researchers so far have used rather simplified empirical and semi-empirical correlations for pressure drop calculations, the range and application of which are fairly limited. Computational Fluid Dynamics (CFD) based techniques have been used to analyze the effect of the presence of solid phase in hydraulic bends. A steady state numerical solution has been obtained from the equations governing turbulent flow in pipe bends carrying spherical capsule train consisting of one to four capsules. The bends under consideration are of 45⁰ and 90⁰ with an inner diameter of 0.1m. The investigation was carried out in the practical range of 0.2 ≤Vb≥ 1.6 m/sec. The computationally obtained data set over a wide range of flow conditions has been used to develop a rigorous model for pressure drop calculations. The pressure drop along the pipe bends, in combination with the pressure drop along the pipes, can be used to calculate the pumping requirements and hence design of the system
Optimal Design of Capsule Transporting Pipeline carrying Spherical Capsules
No full textA capsule pipeline transports material or cargo in capsules propelled by fluid flowing through a pipeline. The cargo may either be contained in capsules (such as wheat enclosed inside sealed cylindrical containers), or may itself be the capsules (such as coal compressed into the shape of a cylinder or sphere). As the concept of capsule transportation is relatively new, the capsule pipelines need to be designed optimally for commercial viability. An optimal design of such a pipeline would have minimum pressure drop due to the presence of the solid medium in the pipeline, which corresponds to minimum head loss and hence minimum pumping power required to drive the capsules and the transporting fluid. The total cost for the manufacturing and maintenance of such pipelines is yet another important variable that needs to be considered for the widespread commercial acceptance of capsule transporting pipelines. To address this, the optimisation technique presented here is based on the least-cost principle. Pressure drop relationships have been incorporated to calculate the pumping requirements for the system. The maintenance and manufacturing costs have been computed separately to analyse their effects on the optimisation process. A design example has been included to show the usage of the model presented. The results indicate that for a specific throughput, there exists an optimum diameter of the pipeline for which the total cost for the piping system is at its minimum
Uniqueness of Normal Forms is Decidable for Shallow Term Rewrite Systems
No full textUniqueness of normal forms (UN=) is an important property of term rewrite systems. UN= is decidable for ground (i.e., variable-free) systems and undecidable in general. Recently it was shown to be decidable for linear, shallow systems. We generalize this previous result and show that this property is decidable for shallow rewrite systems, in contrast to confluence, reachability and other properties, which are all undecidable for flat systems. Our result is also optimal in some sense, since we prove that the UN= property is undecidable for two superclasses of flat systems: left-flat, left-linear systems in which right-hand sides are of depth at most two and right-flat, right-linear systems in which left-hand sides are of depth at most two
Modelling rough interfaces on seismic reflection profiles - the application of fractal concepts
No full textThe distortion of reflection continuity and amplitude by overburden structure in seismic reflection images of the sub- surface is easily recognised and modelled when the wavelength of the shallower structure is relatively large. The effects of shorter wavelength structure although giving rise to little reflective response itself, cause significant distortion of the propagating wavefield, particularly when a moderate or strong acoustic impedance contrast is present in the shallow sub-surface. Here we show how short as well as long spatial wavelengths of horizon roughness affect deeper reflection continuity, and develop a new method using fractal interpolation techniques to predict the total roughness of sub-surface horizons from information contained in seismic reflection sections. Fractally complete depth-velocity models are used in forward models, using the finite difference technique, to produce synthetic seismic profiles. The technique is illustrated with data from the Edoras Bank area of the Rockall Plateau, NE Atlantic, where apparently discontinuous reflectors underlying basalt flows are shown to be from continuous sedimentary horizons distorted by overlying rough horizons
Corrigendum: Capital Inflows and House Prices: Aggregate and Regional Evidence from China
No full textIn the paper ‘Capital Inflows and House Prices: Aggregate and Regional Evidence from China’ by H. An, et al., printed in the December 2016 issue, there was a missing acknowledgement section for funding resources.
On page 451, the acknowledgement section should appear after the corresponding information as:
“Correspondence: Rakesh Gupta, Department of Accounting, Finance and Economics, Griffith Business School, Griffith University, Nathan Campus QLD 4111. [email protected]
*This work was financially supported by the Humanities and Social Science Foundation of Ministry of Education of China (16YJA790001).”
The author apologises for this error and any confusion it may have caused.No Full Tex
Embedding Approximately Low-Dimensional l_2^2 Metrics into l_1
No full textGoemans showed that any n points x_1,..., x_n in d-dimensions satisfying l_2^2 triangle inequalities can be embedded into l_{1}, with worst-case distortion at most sqrt{d}. We consider an extension of this theorem to the case when the points are approximately low-dimensional as opposed to exactly low-dimensional, and prove the following analogous theorem, albeit with average distortion guarantees: There exists an l_{2}^{2}-to-l_{1} embedding with average distortion at most the stable rank, sr(M), of the matrix M consisting of columns {x_i-x_j}_{i<j}. Average distortion embedding suffices for applications such as the SPARSEST CUT problem. Our embedding gives an approximation algorithm for the SPARSEST CUT problem on low threshold-rank graphs, where earlier work was inspired by Lasserre SDP hierarchy, and improves on a previous result of the first and third author [Deshpande and Venkat, in Proc. 17th APPROX, 2014]. Our ideas give a new perspective on l_{2}^{2} metric, an alternate proof of Goemans' theorem, and a simpler proof for average distortion sqrt{d}
Teachers’ and Students' Attitudes Towards Traditional and Computer Assisted Blended Teaching and Learning Processes in Mechanical Engineering Subjects Area
No full textThe effectiveness of traditional teaching-learning process in Computer Aided Design (CAD), Computer Aided Manufacturing CAM and Computer Numerical control CNC (CAD-CAM-CNC) module has been evaluated against recently developed two blended teaching learning models. The blended learning systems have been developed by integrating computer assisted instructions with the traditional teaching learning system. This study in particular reports teachers’ and students’ views about various facets of teaching and learning process under different modes. It has been see that blended learning modes find better acceptance amongst teachers and students as co mpared to traditional teaching mode
Distribution of somatostatin-like immunoreactivity in the brain of the frog, Rana esculenta, during development
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