2,764 research outputs found
A study of flame-vortex interactions in the presence of residual gases
No full textIn this work the effects of residual combustion products from a prior injection on flame extinction characteristics in a Diesel fuel pulse are investigated through a fundamental study. A numerical code with sixth-order accurate spatial discretization and multiple-step chemical kinetics is used to simulate flame-vortex interactions under Diesel conditions in the presence of residual combustion product mixtures. The results indicate that there is a balance between the heating effect of the high-temperature combustion products that enhance flame stability and the dilution effect of the reduced oxygen concentration, which promotes extinction. These counteracting aspects of the entrained combustion products can lead to an ideal dwell time between multiple injection events for optimum benefits in flame stability.Jonathan W. Anders, Rishikesh Venugopal, Vinicio Magi, and John Abraha
Spatial pattern of nerve differentiation in Hydra is due to a pattern of nerve commitment
No full textThe pattern of nerve differentiation along the body column of Hydra was investigated. Nerve precursors in late S phase were labeled with [3H]thymidine and their distribution compared with that of newly differentiated nerves. The two distributions were found to be the same. Based on independent evidence that nerve commitment occurs in mid-to late S phase (G. Venugopal and C. David, 1981, Develop. Biol.83, 361–365) it was concluded that the pattern of nerve differentiation along the body column of Hydra is due to differences in nerve commitment in different body regions. Furthermore, the level of nerve commitment in head and foot tissue is sufficiently high to deplete stem cells in these regions as is observed
Prashanth C. R KB Raja KR Venugopal
No full textThe signature verification system is always the most sought after biometric verification system. Being a behavioral biometric trait which can be imitated, the researcher faces a challenge in designing such a system to counter intrapersonal and interpersonal variations. This papers presents DWT based Off-line Signature Verification using Angular Features (DOSVAF). The signature is resized and Discrete Wavelet Transform (DWT) is applied to get four bands. The approximation band is considered and skeletonized. The exact signature area is cropped and resized so that the fair comparison is made among the signatures to produce better result. The angular features are extracted by dividing the signature image into number of blocks. The angular features of database and test signature are compared using distance metric. It is found that the values of FAR and FRR at optimal threshold are better compared to that of existin
TeraWatt North Atlantic spectral wave model input files (for MIKE 21)
No full textNORTH ATLANTIC MIKE 21 MODEL INPUT FILES
This submission includes the input files for the North Atlantic spectral wave model that is described in [1,2]. It formed part of the TeraWatt and EcoWatt2050 EPSRC projects (grant numbers EP/J010170/1 &
EP/K012851/1 respectively).
The input files require the MIKE 21 modelling suite to run, available commercially from https://www.mikepoweredbydhi.com/; they were created and validated using the 2014 edition. Input files are being stored instead of outputs as per RCUK guidelines due to the size of the output files.
For further information please contact Dr. Vengatesan Venugopal, School of Engineering, University of Edinburgh ([email protected]).
[1] V. Venugopal and R. Nemalidinne, ‘Wave resource assessment for Scottish waters using a large scale North Atlantic spectral wave model’, Renewable Energy, vol. 76, no. Supplement C, pp. 503–525, Apr. 2015.
[2] V. Venugopal, R. Nemalidinne, and A. Vögler, ‘Numerical modelling of wave energy resources and assessment of wave energy extraction by large scale wave farms’, Ocean & Coastal Management, Mar. 2017.See readme.txt
Extinction and Re-Ignition in Non-Premixed Flame-Vortex Interactions under Diesel Conditions
No full textIn this work, 2-D numerical investigations of extinction and re-ignition during interactions of counter-rotating vortex-pairs with a non-premixed flame are carried out under pressures and temperatures encountered in Diesel chambers. A direct-numerical simulation (DNS) code which employs sixth-order spatial accuracy and fourth-order time-integration is employed to solve the Navier-Stokes equations with chemical reactions. N-heptane is chosen as a representative fuel and irreversible single-step and two-step kinetic models are employed. Several representative values for the vortex circulation and length-scale are chosen from the analysis of the near-field of a Diesel jet. Results show that due to the vortex-induced strain, local extinction occurs along the symmetry axis. This extinction is predicted well by 1-D laminar flamelet libraries provided the time-history of the scalar dissipation rate is taken into account. The flame-edges resulting from local extinction interact leading to re-ignition as the initial vortex size approaches the initial flame thickness. This re-ignition phenomenon is 2-D, involves a partially-premixed flame structure and is not predicted by 1-D diffusion flamelet libraries. The results are summarized in terms of a regime diagram constructed from non-dimensional parameters such as the length-scale ratio and the Damkihler number
A Coupled LES-DNS Study of Physicochemical Processes in the Near Field of Transient Jets under Engine Conditions
No full textEntrepreneurial marketing in subsistence marketplaces
No full textThere are more than a billion poverty-stricken entrepreneurs in the world who run micro-enterprises to meet basic consumption needs. This pervasive phenomenon presents an interesting theoretical conundrum - that of consumer-entrepreneur duality. This duality blurs the boundaries between consumption and entrepreneurship, which have traditionally been distinct domains of scholarly inquiry. The research reported in this dissertation aims to a) provide a theoretical foundation for the notion of consumer-entrepreneur duality and b) test the implications of the aforementioned duality empirically. A key insight flowing from the investigations is that factors in the consumption domain impact important outcomes in the entrepreneurial domain and vice versa.Submission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2018-05-01The student, Srinivas Venugopal, accepted the attached license on 2016-04-18 at 08:47.The student, Srinivas Venugopal, submitted this Dissertation for approval on 2016-04-18 at 09:04.This Dissertation was approved for publication on 2016-04-19 at 08:14.DSpace SAF Submission Ingestion Package generated from Vireo submission #9286 on 2016-07-07 at 14:17:05Made available in DSpace on 2016-07-07T21:17:37Z (GMT). No. of bitstreams: 4
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TeraWatt North Atlantic spectral wave model input files (for MIKE 21)
No full textNORTH ATLANTIC MIKE 21 MODEL INPUT FILES This submission includes the input files for the North Atlantic spectral wave model that is described in [1,2]. It formed part of the TeraWatt and EcoWatt2050 EPSRC projects (grant numbers EP/J010170/1 & EP/K012851/1 respectively). The input files require the MIKE 21 modelling suite to run, available commercially from https://www.mikepoweredbydhi.com/; they were created and validated using the 2014 edition. Input files are being stored instead of outputs as per RCUK guidelines due to the size of the output files. For further information please contact Dr. Vengatesan Venugopal, School of Engineering, University of Edinburgh ([email protected]). [1] V. Venugopal and R. Nemalidinne, ‘Wave resource assessment for Scottish waters using a large scale North Atlantic spectral wave model’, Renewable Energy, vol. 76, no. Supplement C, pp. 503–525, Apr. 2015. [2] V. Venugopal, R. Nemalidinne, and A. Vögler, ‘Numerical modelling of wave energy resources and assessment of wave energy extraction by large scale wave farms’, Ocean & Coastal Management, Mar. 2017.Venugopal, Vengatesan. (2017). TeraWatt North Atlantic spectral wave model input files (for MIKE 21), 2010 [dataset]. School of Engineering, University of Edinburgh. http://dx.doi.org/10.7488/ds/2216
MIKE 21 West Orkney Monthly Hs Summary Outputs
No full textMIKE 21 WEST ORKNEY MONTHLY Hs SUMMARY OUTPUTS
This collection of netCDF format files contains monthly summary outputs of significant wave height (Hs) from the West of Orkney MIKE 21 spectral wave model described in [1]. For each month the mean Hs and the values of the 5,10,20...,90,95th percentiles are given for each cell in the model.
The model was designed to study the effects on wave height of both wave energy extraction and climate change.
Four scenarios are included: Present day (2010) with and without wave energy convertors, and future climate (~2050) with and without wave energy convertors. See [1] for more detail on present-day; a future publication will describe the future version.
This model was developed under the TeraWatt and EcoWatt2050 EPSRC projects (grant numbers EP/J010170/1 & EP/K012851/1 respectively). The data archived here are being used within the EcoWatt project for ongoing ecological studies.
For the input files for the model used to produce these outputs, please see submission "WEST ORKNEY MIKE 21 MODEL INPUT FILES" in this repository.
For further information please contact Dr. Vengatesan Venugopal, School of Engineering, University of Edinburgh ([email protected]).
[1] V. Venugopal, R. Nemalidinne, and A. Vögler, ‘Numerical modelling of wave energy resources and assessment of wave energy extraction by large scale wave farms’, Ocean & Coastal Management, Mar. 2017
Drag and inertia coefficients for horizontally submerged rectangular cylinders in waves and currents
No full textThe results of an experimental investigation carried out to measure combined wave and current loads on horizontally submerged square and rectangular cylinders are reported in this paper. The wave and current induced forces on a section of the cylinders with breadth-depth (aspect) ratios equal to 1, 0.5, and 0.75 are measured in a wave tank. The maximum value of Keulegan-Carpenter (KC) number obtained in waves alone is about 5 and Reynolds (Re) number ranged from 6.3976103 to 1.186105. The drag (CD) and inertia (CM) coefficients for each cylinder are evaluated using measured sectional wave forces and particle kinematics calculated from linear wave theory. The values of CD and CM obtained for waves alone have already been reported (Venugopal, V., Varyani, K. S., and Barltrop, N. D. P. Wave force coefficients for horizontally submerged rectangular cylinders. Ocean Engineering, 2006, 33, 11-12, 1669-1704) and the coefficients derived in combined waves and currents are presented here. The results indicate that both drag and inertia coefficients are strongly affected by the presenceof the current and show different trends for different cylinders. The values of the vertical component inertia coefficients (CMY) in waves and currents are generally smaller than the inertia coefficients obtained in waves alone, irrespective of the current's magnitude and direction. The results also illustrate the effect of a cylinder's aspect ratio on force coefficients. This study will be useful in the design of offshore structures whose columns and caissons are rectangular sections
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