Documents disponibles écrits par cet auteur

Development of soft sensor to identify flow regimes in horizontal pipe using digital signal processing technique / Kishore Muvvala in Industrial & engineering chemistry research, Vol. 49 N° 6 (Mars 2010) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 49 N° 6 (Mars 2010) . - pp. 3001–3010 Titre : Development of soft sensor to identify flow regimes in horizontal pipe using digital signal processing technique Type de document : texte imprimé Auteurs : Kishore Muvvala, Auteur ; V. Kumar, Auteur ; B. C. Meikap, Auteur Année de publication : 2010 Article en page(s) : pp. 3001–3010 Note générale : Industrial Chemistry Langues : Anglais (eng) Mots-clés : Development--Sensor--Identify--Flow--Regimes--Horizontal--Pipe--Digital--Signal--Processing--Technique Résumé : The work described in this article is a new analytical and experimental study of two-phase gas−liquid horizontal flow in a conduit for flow pattern identification by a digital signal processing technique. The data are acquired online using a pressure transducer and a National Instruments data acquisition card. The true signal voltage changes rather smoothly as a function of the number of samples, whereas many kinds of noise are added; as a result, rapid, random changes in amplitude from point to point within the signal are observed. To reduce the noise, a smoothing technique is employed. In the smoothing, the data points of a signal are modified so that the individual points that are higher than the immediately adjacent points are reduced and points that are lower than the adjacent points are increased. This naturally leads to a smoother signal. For this purpose, the simplest smoothing algorithm, namely, a simple moving average, is employed and is able to successfully eliminate the noise. After eliminating the noise, the slope of the curve is continuously tracked to determine sudden or abrupt changes. It is interesting to note that, from the signal obtained, the slope is always decreasing in nature and the magnitude is on the order of 5 × 10−3. According to the data and the slope, different flow regimes can be identified by using cross-correlation method. Note de contenu : Bibiogr. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9019215 [article] Development of soft sensor to identify flow regimes in horizontal pipe using digital signal processing technique [texte imprimé] / Kishore Muvvala, Auteur ; V. Kumar, Auteur ; B. C. Meikap, Auteur . - 2010 . - pp. 3001–3010. Industrial Chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 6 (Mars 2010) . - pp. 3001–3010 Mots-clés : Development--Sensor--Identify--Flow--Regimes--Horizontal--Pipe--Digital--Signal--Processing--Technique Résumé : The work described in this article is a new analytical and experimental study of two-phase gas−liquid horizontal flow in a conduit for flow pattern identification by a digital signal processing technique. The data are acquired online using a pressure transducer and a National Instruments data acquisition card. The true signal voltage changes rather smoothly as a function of the number of samples, whereas many kinds of noise are added; as a result, rapid, random changes in amplitude from point to point within the signal are observed. To reduce the noise, a smoothing technique is employed. In the smoothing, the data points of a signal are modified so that the individual points that are higher than the immediately adjacent points are reduced and points that are lower than the adjacent points are increased. This naturally leads to a smoother signal. For this purpose, the simplest smoothing algorithm, namely, a simple moving average, is employed and is able to successfully eliminate the noise. After eliminating the noise, the slope of the curve is continuously tracked to determine sudden or abrupt changes. It is interesting to note that, from the signal obtained, the slope is always decreasing in nature and the magnitude is on the order of 5 × 10−3. According to the data and the slope, different flow regimes can be identified by using cross-correlation method. Note de contenu : Bibiogr. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9019215

Empirical investigation of retail expansion and cannibalization in a dynamic environment / Joseph Pancras in Management science, Vol. 58 N° 11 (Novembre 2012) 

Public ISBD [article]  in Management science > Vol. 58 N° 11 (Novembre 2012) . - pp. 2001-2018 Titre : Empirical investigation of retail expansion and cannibalization in a dynamic environment Type de document : texte imprimé Auteurs : Joseph Pancras, Auteur ; S. Sriram, Auteur ; V. Kumar, Auteur Année de publication : 2013 Article en page(s) : pp. 2001-2018 Note générale : Management Langues : Anglais (eng) Mots-clés : Marketing  Retailing  and  wholesaling  Advertising  and  media  Economics  Econometrics Résumé : Managers of retail chains who seek to add new stores or close existing ones need to know the net impact of a store's opening/closure on the overall chain performance. This requires inferring the extent to which each store generates incremental sales as opposed to competing with other stores belonging to the chain for the same set of customers. However, when the chain is experiencing a growth or a decline in sales, not accounting for these dynamics in goodwill is likely to yield misleading estimates of incremental sales versus cannibalization. Moreover, firms might have been strategic in opening outlets in locations with favorable characteristics. We need to control for this location endogeneity while inferring the marginal effect of store opening/closure. In this paper, we develop a demand model that accounts for dynamics in goodwill, location endogeneity, and spatial competition between geographically proximate retail outlets. We calibrate the model parameters on both attitudinal and behavioral data for a fast food chain in a large U.S. city. The results imply that consumers perceive a travel cost of $0.60 per mile. As regards the composition of sales at individual stores, on average, 86.7% of sales constitute incremental purchases with the rest derived from cannibalized sales from nearby stores belonging to the chain. We also find significant decay in cannibalization with distance such that when the distance between stores increases by one mile, the sales lost due to cannibalization decreases by 28.1%; there is virtually no cannibalization at a distance of 10 miles. In terms of managerial applications, we discuss how managers can use the model presented in this paper to make two key decisions: (a) isolating locations that can be closed by identifying stores that yield the lowest marginal benefit to the chain and (b) dealing with franchisees' potential concerns about cannibalization. ISSN : 0025-1909 En ligne : http://mansci.journal.informs.org/content/58/11/2001.abstract [article] Empirical investigation of retail expansion and cannibalization in a dynamic environment [texte imprimé] / Joseph Pancras, Auteur ; S. Sriram, Auteur ; V. Kumar, Auteur . - 2013 . - pp. 2001-2018. Management Langues : Anglais (eng) in Management science > Vol. 58 N° 11 (Novembre 2012) . - pp. 2001-2018 Mots-clés : Marketing  Retailing  and  wholesaling  Advertising  and  media  Economics  Econometrics Résumé : Managers of retail chains who seek to add new stores or close existing ones need to know the net impact of a store's opening/closure on the overall chain performance. This requires inferring the extent to which each store generates incremental sales as opposed to competing with other stores belonging to the chain for the same set of customers. However, when the chain is experiencing a growth or a decline in sales, not accounting for these dynamics in goodwill is likely to yield misleading estimates of incremental sales versus cannibalization. Moreover, firms might have been strategic in opening outlets in locations with favorable characteristics. We need to control for this location endogeneity while inferring the marginal effect of store opening/closure. In this paper, we develop a demand model that accounts for dynamics in goodwill, location endogeneity, and spatial competition between geographically proximate retail outlets. We calibrate the model parameters on both attitudinal and behavioral data for a fast food chain in a large U.S. city. The results imply that consumers perceive a travel cost of $0.60 per mile. As regards the composition of sales at individual stores, on average, 86.7% of sales constitute incremental purchases with the rest derived from cannibalized sales from nearby stores belonging to the chain. We also find significant decay in cannibalization with distance such that when the distance between stores increases by one mile, the sales lost due to cannibalization decreases by 28.1%; there is virtually no cannibalization at a distance of 10 miles. In terms of managerial applications, we discuss how managers can use the model presented in this paper to make two key decisions: (a) isolating locations that can be closed by identifying stores that yield the lowest marginal benefit to the chain and (b) dealing with franchisees' potential concerns about cannibalization. ISSN : 0025-1909 En ligne : http://mansci.journal.informs.org/content/58/11/2001.abstract

Optimal control of matrix-converter-based WECS for performance enhancement and efficiency optimization / V. Kumar in IEEE transactions on energy conversion, Vol. 24 N°1 (Mars 2009) 

Public ISBD [article]  in IEEE transactions on energy conversion > Vol. 24 N°1 (Mars 2009) . - pp. 264 - 273 Titre : Optimal control of matrix-converter-based WECS for performance enhancement and efficiency optimization Type de document : texte imprimé Auteurs : V. Kumar, Auteur ; Joshi, R. R., Auteur ; Bansal, R. C., Auteur Année de publication : 2009 Article en page(s) : pp. 264 - 273 Note générale : energy conversion Langues : Anglais (eng) Mots-clés : Asynchronous  generators;  fuzzy  control;  matrix  convertors;  optimal  control;  optimisation;  power  factor;  power  generation  control;  power  grids;  wind  power  plants;  wind  turbines Résumé : This paper describes a new wind energy conversion scheme, where fuzzy logic principles and four-leg-improved novel matrix converter (MC) model are used for performance enhancement and efficiency optimization, particularly for sites where most of the time low wind speeds prevail. The MC is intended as the interface medium between the induction generator and the utility grid. The power factor at the interface with the grid is controlled by the MC to ensure purely active power injection into the grid for optimal utilization of the installed wind turbine capacity. The generation system has fuzzy logic control with vector control in the inner loops. Fuzzy controller tracks the angular frequency with the wind velocity to extract the maximum power and programs the machine flux for light load efficiency improvement. The complete control system has been developed, analyzed, and validated by simulation study. En ligne : http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=4749289&sortType%3Das [...] [article] Optimal control of matrix-converter-based WECS for performance enhancement and efficiency optimization [texte imprimé] / V. Kumar, Auteur ; Joshi, R. R., Auteur ; Bansal, R. C., Auteur . - 2009 . - pp. 264 - 273. energy conversion Langues : Anglais (eng) in IEEE transactions on energy conversion > Vol. 24 N°1 (Mars 2009) . - pp. 264 - 273 Mots-clés : Asynchronous  generators;  fuzzy  control;  matrix  convertors;  optimal  control;  optimisation;  power  factor;  power  generation  control;  power  grids;  wind  power  plants;  wind  turbines Résumé : This paper describes a new wind energy conversion scheme, where fuzzy logic principles and four-leg-improved novel matrix converter (MC) model are used for performance enhancement and efficiency optimization, particularly for sites where most of the time low wind speeds prevail. The MC is intended as the interface medium between the induction generator and the utility grid. The power factor at the interface with the grid is controlled by the MC to ensure purely active power injection into the grid for optimal utilization of the installed wind turbine capacity. The generation system has fuzzy logic control with vector control in the inner loops. Fuzzy controller tracks the angular frequency with the wind velocity to extract the maximum power and programs the machine flux for light load efficiency improvement. The complete control system has been developed, analyzed, and validated by simulation study. En ligne : http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=4749289&sortType%3Das [...]