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631 results on '"Ghosh, Amitava"'

256. Application of artificial neural network model in predicting physicochemical characteristics of pharmaceutically developed wafers of loratadine

Author

Chakraborty Prithviraj, Parcha Versha, Ghosh Amitava, and ChakrabortyD Debarupa

Subjects
Neural network software, Artificial neural network, Multilayer perceptron, Conjugate gradient method, Factorial experiment, General Pharmacology, Toxicology and Pharmaceutics, Perceptron, Biological system, Backpropagation, Test data, Mathematics
Abstract

This study aimed to apply the simultaneous optimization method incorporating artificial neural network (ANN) using multi‐layer perceptron (MLP) model to develop buccoadhesive pharmaceutical wafers containing loratadine with an optimized physicochemical property and drug release. The amount of sodium carboxymethyl cellulose and lactose monohydrate at three levels (−1, 0, +1) for each was selected as casual factors. Bioadhesive strength, disintegration time, percent swelling index and t70% as wafer properties were selected as output variables. Nine buccoadhesive wafers were prepared according to a 32 factorial design and their physicochemical property and dissolution tests were performed. Commercially available Statistica Neural Network Software (Stat Soft, Inc., Tulsa, OK, USA) was used throughout the study. The training process of MLP was completed until a satisfactory value of root mean square for the test data was obtained using back propagation, conjugate gradient descent method. This work exemplifies the probability for an ANN with MLP, to support in development of buccoadhesive wafers with enviable characteristics. Key words: Artificial neural network, buccoadhesive, loratadine, multilayer perceptron, pharmaceutical wafers

Published
2015

257. Grinding of Ti-6Al-4V Under Small Quantity Cooling Lubrication Environment Using Alumina and MWCNT Nanofluids.

Author

Paul, Sourabh, Singh, Abhinav Kumar, and Ghosh, Amitava

Subjects
GRINDING & polishing, LUBRICATION & lubricants, NANOFLUIDS, CARBON nanotubes, CHEMICAL affinity
Abstract

Ti-6Al-4V is a difficult-to-grind material as chips tend to adhere to the grit materials of an abrasive wheel due to its chemical affinity. In the present work, it has been attempted to improve the grindability by application of small quantity cooling lubrication (SQCL) technology using nanofluids, namely, multiwalled carbon nanotube (MWCNT) and alumina nanofluid. The suitability of nanofluids was experimentally evaluated in reciprocating surface grinding using a vitrified SiC wheel. Substantial improvement in grindability under the influence of MWCNT nanofluid (SQCL) could be achieved compared to soluble oil (flood). Reduction of specific grinding forces and specific energy was observed due to the combined effect of superior heat dissipation and lubrication abilities; when the latter one was realized through on-site rolling of MWCNT strands, inter-tubular slip and solid lubrication of the film adhered onto the wheel surface. These outperforming characteristics of MWCNT nanofluid helped in retaining grit sharpness superiorly, thus resulting in better surface finish and less re-deposition of metal on the ground workpiece. On the contrary, Al2O3 nanofluid (SQCL) underperformed even soluble oil (flood). For an ageing effect, Al2O3 nanoparticles resulted in abrasive agglomerates, which led to its failure, despite its good heat dissipation capability. [ABSTRACT FROM AUTHOR]

Published
2017
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281. Weighted spline based integration for reconstruction of freeform wavefront

Author

Pant, Kamal K., Burada, Dali R., Bichra, Mohamed, Ghosh, Amitava, Khan, Gufran S., Sinzinger, Stefan, and Shakher, Chandra

Abstract

In the present work, a spline-based integration technique for the reconstruction of a freeform wavefront from the slope data has been implemented. The slope data of a freeform surface contain noise due to their machining process and that introduces reconstruction error. We have proposed a weighted cubic spline based least square integration method (WCSLI) for the faithful reconstruction of a wavefront from noisy slope data. In the proposed method, the measured slope data are fitted into a piecewise polynomial. The fitted coefficients are determined by using a smoothing cubic spline fitting method. The smoothing parameter locally assigns relative weight to the fitted slope data. The fitted slope data are then integrated using the standard least squares technique to reconstruct the freeform wavefront. Simulation studies show the improved result using the proposed technique as compared to the existing cubic spline-based integration (CSLI) and the Southwell methods. The proposed reconstruction method has been experimentally implemented to a subaperture stitching-based measurement of a freeform wavefront using a scanning Shack–Hartmann sensor. The boundary artifacts are minimal in WCSLI which improves the subaperture stitching accuracy and demonstrates an improved Shack–Hartmann sensor for freeform metrology application.

Published
2018

282. Toward the Coexistence of 5G MmWave Networks with Incumbent Systems beyond 70 GHz

Author

Hattab, Ghaith, Visotsky, Eugene, Cudak, Mark, and Ghosh, Amitava

Abstract

Cellular networks are on the verge of enabling mobile millimeter-wave access beyond the traditional sub-6 GHz spectrum. Indeed, standardization of 5G-NR has already started, with an eye on enabling gigabit connectivity over 28 GHz and 39 GHz bands. Nevertheless, there remains a plethora of spectrum beyond these bands, and specifically at 70 GHz (71-76 GHz) and 80 GHz (81-86 GHz). A key issue in the aforementioned bands is the presence of licensed incumbent systems that provide point-to-point services. This article provides an overview of recent efforts toward the coexistence of 5G systems with these incumbents. Specifically, we analyze the 5G interference into incumbent receivers and present practical active and passive interference management techniques. We validate the 5G coexistence with detailed network simulations and show the feasibility of 5G connectivity beyond 70 GHz using an experimental prototype. Finally, we highlight future research venues for 5G coexistence with incumbent systems.

Published
2018
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289. Modeling, Analysis and Design for Carrier Aggregation in Heterogeneous Cellular Networks

Author

Lin, Xingqin, Andrews, Jeffrey G., Ghosh, Amitava, Lin, Xingqin, Andrews, Jeffrey G., and Ghosh, Amitava

Abstract

Carrier aggregation (CA) and small cells are two distinct features of next-generation cellular networks. Cellular networks with small cells take on a very heterogeneous characteristic, and are often referred to as HetNets. In this paper, we introduce a load-aware model for CA-enabled \textit{multi}-band HetNets. Under this model, the impact of biasing can be more appropriately characterized; for example, it is observed that with large enough biasing, the spectral efficiency of small cells may increase while its counterpart in a fully-loaded model always decreases. Further, our analysis reveals that the peak data rate does not depend on the base station density and transmit powers; this strongly motivates other approaches e.g. CA to increase the peak data rate. Last but not least, different band deployment configurations are studied and compared. We find that with large enough small cell density, spatial reuse with small cells outperforms adding more spectrum for increasing user rate. More generally, universal cochannel deployment typically yields the largest rate; and thus a capacity loss exists in orthogonal deployment. This performance gap can be reduced by appropriately tuning the HetNet coverage distribution (e.g. by optimizing biasing factors)., Comment: submitted to IEEE Transactions on Communications, Nov. 2012

Published
2012
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