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This paper is to show the significance of Callaway's correction term κc for theoretical analysis of lattice thermal conductivity κ of pure LiF, over the temperature range 2-50 K, by using authors adapted Callaway-Holland model. To study the effect of scattering of phonons by crystal boundary alone, different perspectives have been looked into. That includes samples of various sized crystals cleaved from the same isotopically and chemically pure boule. Different empirical expressions for three phonon relaxation rates τ-13 ph - for the entire temperature range, as have been proposed by the author earlier, have been used. Anisotropic and dispersive point defect as well as boundary scattering relaxation rates are used. The main argument of the paper is that κc cannot be neglected as its contribution is even more or nearly equal to the Callaway's Debye term contribution near the conductivity peak. Hence, its inclusion in the calculation of total lattice thermal conductivity κ is the only way to provide the best fitting of the experimental data for crystals of different sizes with simultaneously taking the same three phonon and point defect parameters. It has also been shown that the effect of boundary scattering is sizable even beyond the conductivity maximum, in the case of isotopically pure LiF. This is in contradiction to other researchers who suggest that boundary scattering is only a low temperature phenomenon. Theoretically justified parameters have been used to obtain excellent agreement with the result reported by Thacher. © 2017 Old City Publishing, Inc.


Sepehri A.,Shahid Bahonar University of Kerman | Rahaman F.,Jadavpur University | Setare M.R.,University of Kurdistan | Pradhan A.,GLA University | And 4 more authors.
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2015

We propose a cosmological model that unifies inflation, deceleration and acceleration phases of expansion history by a BIonic system. At the beginning, there are k black fundamental strings that transited to the BIon configuration at a given corresponding point. Here, two coupled universes, brane and antibrane, are created interacting each other through a wormhole and inflate. With decreasing temperature, the energy of this wormhole flows into the universe branes and leads to inflation. After a short time, the wormhole evaporates, the inflation ends and a deceleration epoch starts. By approaching the brane and antibrane universes together, a tachyon is born, grows and causes the creation of a new wormhole. At this time, the brane and antibrane universes result connected again and the late-time acceleration era of the universe begins. We compare our model with previous unified phantom models and observational data obtaining some cosmological parameters like temperature in terms of time. We also find that deceleration parameter is negative during inflation and late-time acceleration epochs, while it is positive during the deceleration era. This means that the model is consistent, in principle, with cosmological observations. © 2015 The Authors.


Sepehri A.,Shahid Bahonar University of Kerman | Rahaman F.,Jadavpur University | Pradhan A.,GLA University | Sardar I.H.,Jadavpur University
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2015

Recently, Padmanabhan [. arXiv:1206.4916 [hep-th]] argued that the expansion rate of the universe can be thought of as the emergence of space as cosmic time progresses and is related to the difference between the surface degrees of freedom on the holographic horizon and the bulk degrees of freedom inside. The main question arises as to what is the origin of emergence of space in 4D universe. We answer this question in BIonic system. The BIon is a configuration in flat space of a D-brane and a parallel anti-D-brane connected by a thin shell wormhole with F-string charge. We propose a new model that allows that all degrees of freedom inside and outside the universe are controlled by the evolutions of BIon in extra dimension and tend to degrees of freedom of black F-string in string theory or black M2-brane in M-theory. © 2014 The Authors.


Sharma A.K.,Indian School of Mines | Tiwari A.K.,GLA University | Dixit A.R.,Indian School of Mines
Renewable and Sustainable Energy Reviews | Year: 2016

A colloidal mixture of nanometre-sized (<100 nm) metallic and non-metallic particles in conventional fluid is called nanofluid. Nanofluids are considered to be potential heat transfer fluids because of their superior thermal and tribological properties. In recent period, nanofluids have been the focus of attention of the researchers. This paper presents a summary of a number of important research works that have been published on rheological behaviour of nanofluids. This review article not only discusses the influence of particle shape and shear rate range on rheological behaviour of nanofluids but also studies other factors affecting the rheological behaviour. These other factors include nanoparticle type, volumetric concentration in different base fluids, addition of surfactant and externally applied magnetic field. From the literature review, it has been found that particle shape, its concentration, shear rate range, surfactant and magnetic field significantly affect the rheological behaviour of any nanofluid. It has been observed that nanofluids containing spherical nanoparticles are more likely to exhibit Newtonian behaviour and those containing nanotubes show non-Newtonian flow behaviour. Furthermore, nanofluids show Newtonian behaviour at low shear rate values while behave as non-Newtonian fluid at high shear rate values. Authors have also identified the inadequacies in the research works so far which require further investigations. © 2015 Elsevier Ltd. All right sreserved.


Dubey S.R.,GLA University | Jalal A.S.,GLA University
Procedia Engineering | Year: 2012

Efficient detection of 'species and variety' of fruits and vegetables is one of the major challenges in the fruit recognition. This paper presents a texture feature based on the sum and difference of the intensity values of the neighboring pixels of the color images. The proposed improved sum and difference histogram (ISADli) texture feature is an extension of the Unser's descriptor. The result shows that proposed texture feature performs better than the other state of the art color and texture features in the fruit and vegetables classification. The classification accuracy for the proposed ISADH texture feature is achieved up to 99%. © 2012 Published by Elsevier Ltd.


Saxena K.K.,GLA University | Lal A.,Sardar Vallabhbhai National Institute of Technology, Surat
Procedia Engineering | Year: 2012

Carbon nanotubes () having pristine structure (i.e. structure without any defect) have very high mechanical properties. However, CNTs suffer from defects which can appear during purification, production or deliberately introduced by chemical treatment. The present study is based on comparative investigation of effects produced by Stone-Wales (S-W) and vacancy defects (VD) on the mechanical performance of single walled carbon nanotubes (SWCNT). The defects have been varied from 1 to 4 in both VD and S-W. In order to investigate the effect of both the defects on the material properties of CNT, molecular dynamics (MD) simulations have been used. In this study, a series of MD models (inclusion of number of S-W and VD) have been built to simulate the effects of defects on the mechanical performance of SWCNTs. MD simulation has been carried out on a 42.59A long armchair (6, 6) and (10, 10) SWCNTs by varying relative positions and orientations. Results show that the defects have reduced the tensile strength and strain more in VD as compare to S-W. This has been reduced by an average value of 23.48% and 28.2% respectively for 4 vacancy defects (4VD). Simulation results also show that more energy is required to stabilize the structure which comprises of VD. The increase in the energy value on an average is 35.52% for 4 VD as compared to pristine CNT. The Young's modulus of defected CNTs has also been calculated by increasing the lattice size in the successive increments of 25% by volume and it has been found that the Young's modulus of pristine CNT is weakened by 9.38% for S-W defects. © 2012 Published by Elsevier Ltd.


Verma S.K.,GLA University | Tiwari A.K.,GLA University
Materials Today: Proceedings | Year: 2015

Nanoparticles are innovative materials getting worldwide attention due to their inherent characteristics. Nanofluids exhibits enhanced heat absorbing and heat transport ability, credited to nanoparicles suspended in base- fluids. The cardinal factor which is responsible for enhanced heat transfer and absorption ability of Nanofluids is multiplication of surface to volume ratio of nanoparicles. Nanofluids are nanoparicles suspended in a base fluids, it can be considered liquid nano-composites (homogeneous solution of suspended nanoparicles in base fluids). These Nanofluids are now being used as working fluids to absorb solar insolence and transfer it to another fluids at appreciably enhanced rate as reported by many researcher and nano research centres all over the world. Our analysis is based on progressive evaluation of application of Nanofluids for enhancement of solar collector efficiency. Review of previous works based on experimental and model studies have established that nanofluids have great potential for cooling various thermal systems. © 2015 Elsevier Ltd.


Pandey P.,GLA University
International Conference on Advanced Computing and Communication Technologies, ACCT | Year: 2013

One of the most valuable asset in any software industry is the correct estimation of effort and hence cost estimation of the software to be developed by them. Because of the highly dynamic nature of the Software development, it becomes more and more difficult to get a correct software effort estimation and software cost estimation, which is one of the most important factor which makes software more competitive and is essential for controlling Software Development Cost. Software Cost Estimation is one of the challenging managerial activity, because values of many of the variables are not known and not easy to predict at an early stage of Software Development. An ideal Software Cost Estimation Model should provide ample confidence, precision and accuracy from its predictions. In this paper, we have performed an analysis of most of the algorithmic techniques which has been developed till now for Software Cost Estimation. We have also tried to analyze the advantages and shortcomings of every technique. © 2013 IEEE.


Verma S.K.,GLA University | Tiwari A.K.,GLA University
Energy Conversion and Management | Year: 2015

In recent times solar energy has attracted the attention of scientists to a great deal. On the surface, there are two reasons for it: primarily, the scientists are interested in it with the intent to innovating new devices and secondly, developing new methods to harness it. Miniaturization of devices and energy efficiency are the major focal domains around which new materials are being worked on. The design of solar system may get some basic changes, if the new materials get applied successfully. Albeit, the nanofluids are a comparatively recent innovation which exhibit enhanced heat absorbing and heat transport ability. This paper intends to reinforce the working of nanofluids applied on solar system in the light of works done earlier; it further also explores the variable performance of the solar-system with and without application of nano-fluids. This work has been segmented into two parts: the first part focuses on presenting the experimental and numerical results for the thermal conductivity, viscosity, specific heat and the heat transfer coefficient reported by several authors. The second part deals with the application of nanofluids on different types of solar systems: solar collectors, photovoltaic systems, and solar thermoelectric and energy storage system. A study of the works earlier done seems to be suggesting that the nanofluids have great potential to enhance the functioning of various thermal systems. The recent results of the application of nanofluids in PV/T systems too have been consolidating. It can be safely assumed further that it might enhance the overall performance of the solar energy conversion process. © 2015 Elsevier Ltd. All rights reserved.


Pandey P.,GLA University
Proceedings of the 2013 3rd IEEE International Advance Computing Conference, IACC 2013 | Year: 2013

In today's competitive world consideration of maintaining the security of information is must. Nowadays LAN is generally the most common and popular network domain. Network domains are always prone to number of network attacks. One of the most dangerous form of such network attacks is ARP Cache Poisoning also known as ARP Spoofing. ARP is a stateless protocol and ARP Spoofing takes place mainly because it lacks any mechanism of verifying the identity of sending host. It has been seen that most of the LAN attacks results from ARP Spoofing. So prevention, detection and mitigation of this problem can stop number of network attacks. ARP Spoofing is the act of vindictively changing the IP,MAC associations stored in ARP cache of any network host. In this paper we have proposed a probe based technique with an Enhanced Spoof Detection Engine (E- SDE) which not only detects ARP Spoofing but also identifies the genuine IP,MAC association. ARP and ICMP packets have been used as probe packets. Working of E-SDE is explained with the help of algorithm. We have also proposed an attacking model to clearly understand the incremental development of E-SDE to work effectively against most of the type of attackers. We have also measured the network traffic added by the proposed technique. © 2013 IEEE.

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