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Secure Device to Device Communications using Lightweight Cryptographic Protocol
Ajith Kumar, V,Reddy, K Satyanarayan International Journal of Computer ScienceNetwork S 2021 International journal of computer science and netw Vol.21 No.11
The device to device (D2D) communication is an important and emerging area for future cellular networks. It is concerned about all aspect of secure data transmission between end devices along with originality of the data. In this paradigm, the major concerns are about how keys are delivered between the devices when the devices require the cryptographic keys. Another major concern is how effectively the receiver device verifies the data sent by the sender device which means that the receiver checks the originality of the data. In order to fulfill these requirements, the proposed system able to derive a cryptographic key using a single secret key and these derived keys are securely transmitted to the intended receiver with procedure called mutual authentication. Initially, derived keys are computed by applying robust procedure so that any adversary feel difficulties for cracking the keys. The experimental results shows that both sender and receiver can identify themselves and receiver device will decrypt the data only after verifying the originality of the data. Only the devices which are mutually authenticated each other can interchange the data so that entry of the intruder node at any stage is not possible.
Interference excitation of a square section cylinder
R. Ajith Kumar,B. H. L.Gowda,손창현 대한기계학회 2008 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.22 No.3
Wind tunnel experiments were conducted to study the interference excitation of a square section cylinder (test cylinder) and the results are reported in this paper. The study was carried out at some specific relative positions identified between the test cylinder (side dimension B) and the interfering cylinder (side dimension b) so that the latter is never upstream of the former. Experiments were carried out for the b/B ratios of 0.5, 1.0, 1.5 & 2.0. In this paper, emphasis is laid on bringing out the influence of b/B ratio on the vibratory response of the test cylinder, considering a few interference positions. The results show that at a particular relative position, the magnitude of vibrations and the response trend of the test cylinder are markedly influenced by the b/B ratio. Under certain combinations of b/B ratio, relative position and reduced velocity, test cylinder vibrations are considerably magnified and in certain other combinations they are suppressed. Flow visualization results are provided in an attempt to bring out the influence of b/B ratio and also to explain the observed vibratory features of the test cylinder.
Influence of corner radius on the near wake structure of a transversely oscillating square cylinder
R. Ajith Kumar,손창현,B. H. Lakshmana Gowda 대한기계학회 2009 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.23 No.9
The near wake flow field features of transversely oscillating square section cylinders with different corner radii were studied in an attempt to assess the influence of corner radius. The investigation was performed by using particle image velocimetry (PIV) technique in a water channel with a turbulence intensity of 6.5%. Five models were studied with r/B=0, 0.1, 0.2, 0.3 and 0.5 (r is the corner radius and B is the characteristic dimension of the body), and the body oscillation was limited to lock-in condition (at fe/fo=1.0; fe is the excitation frequency and fo is the vortex shedding frequency from a stationary cylinder at the same Re). The corner radius was found to significantly influence the flow features around the bodies. Except for r/B=0.5, for all the other cases of r/B ratios, cycle-to cycle variation in the mode of vortex shedding was observed in the case of oscillating cylinders inducing highly non-linear wake characteristics. Apart from variation in the shedding mode, changes in shedding cycle timing were also observed for sharp and rounded square cylinders. The hgher the r/B ratio, shedding in the near wake was found to be more uniform (lesser variation in shedding cycle timings). Another admissible shedding mechanism is newly identified to operate in the near wake of oscillating cylinders now being called as the ‘passive shedding’ mechanism. Results indicate that increasing the corner radius suppresses the possible instabilities of the cylinder.
A PIV study of the near wake flow features of a square cylinder: influence of corner radius
R. Ajith Kumar,손창현,B. H. Lakshmana Gowda 대한기계학회 2015 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.29 No.2
In this study, the near wake characteristics of transversely oscillating square-section cylinders with different corner radii were investigatedusing the particle image velocimetry (PIV) technique in a water channel with turbulence intensity of 6.5%. Five models with r/B =0, 0.1, 0.2, 0.3, and 0.5, respectively (where r and B represent the corner radius and the characteristic dimension of the body, respectively),were studied, with the body oscillation limited to that under the lock-in condition. Corner radius was found to significantly influence thecharacteristics of the flow around the bodies, both under stationary and oscillating conditions. The results indicate that the Strouhal numberand vortex strength of the flow increase and decrease, respectively, with an increase in the r/B ratio. The spacing between two rows ofvortices (b) as well as that between consecutive vortices in a row (a) was also found to decrease with the increase in the corner radius. The b/a ratio was found to be nearly independent of the r/B ratio and body oscillation.
Microstructural Evolution and Mechanical Properties of Misch Metal Added Mg-Si Alloys
K. K. Ajith Kumar,U. T. S. Pillai,B. C. Pai,M. Chakraborty 대한금속·재료학회 2013 METALS AND MATERIALS International Vol.19 No.6
Effect of misch metal additions (0.3, 0.6, 0.9 and 1.2 wt%) on the refinement of Mg2Si phase in Mg-1.15Si alloy has been studied and compared with the base alloy. MM addition effectively refines the microstructure by breaking the α-Mg halos and lamellar eutectic phase and the maximum refinement is obtained for 0.6 MM addition. For higher MM additions (0.9 and 1.2 wt%), the refinement effect gets reduced and the formation of RE-Si compound is dominated. Improved tensile properties are obtained with the addition of MM and are attributed to the refinement of microstructure and the presence RE-Si compound. The tensile properties obtained are correlated with the microstructure and mirofractomechnisms.
Generalized chorea due to secondary polycythemia responding to phlebotomy
Ajith Cherian,Naveen Kumar Paramasivan,Divya Kalikavil Puthanveedu,Syam Krishnan,Amitha Radhakrishnan Nair 대한파킨슨병및이상운동질환학회 2021 Journal Of Movement Disorders Vol.14 No.1
Chorea can be seen in association with polycythemia rubra vera (PV) or primary polycythemia, especially in elderly women. However, chorea due to secondary polycythemia is rare, and we report a case in an adolescent boy due to congenital cyanotic heart disease and its rewarding response to phlebotomy.
Design and Analysis of Two Stage Model for Effective Beam forming using MATLAB and VerilogHDL
Devi Sivaraman,Ajith Kumar P.C,Sundaramoorthy T,Neeraj Kr. Shukla 보안공학연구지원센터 2016 International Journal of Signal Processing, Image Vol.9 No.4
Beam forming is a technique in signal processing that has found widespread applications in fields such as radar, wireless communication, bio-medical ultrasounds and so on. Beam forming consist of an array of antennas whose radiation pattern are adjusted to a particular direction. This paper aims in implementing a two stage design for acoustic beam forming using MATLAB and Verilog HDL. First stage is a delay and sum beam former used to obtain beams from a particular direction while the second stage is an LMS model based on Least Mean Square (LMS) algorithm. This stage improves the efficiency of delay sum by removing the unwanted signals. Different hardware parameters like logic utilization, memory usage, CPU time and delay of this design are analyzed to determine its characteristics as compared to delay sum and LMS. This study found that the two stage model gives better beam forming and noise removal than when the stages are implemented independently.
Nisha Kavassery Venkateswaran,Kumar Ajith Uppunda 대한청각학회 2022 Journal of Audiology & Otology Vol.26 No.3
Background and Objectives: This study compared the effectiveness of two spatial training programs using real and virtual sound sources in refining spatial acuity skills in listeners with normal hearing.Subjects and Methods: The study was conducted on two groups of 10 participants each; groups I and II underwent spatial training using real and virtual sound sources, respectively. The study was conducted in three phases: pre-training, training, and post-training phases. At the pre- and post-training phases, the spatial acuity of the participants was measured using real sound sources through the localization test, and virtual sound sources through the virtual acoustic space identification (VASI) test. The thresholds of interaural time difference (ITD) and interaural level difference (ILD) were also measured. In the training phase, Group I participants underwent localization training using loudspeakers in free field, while participants in Group II were subjected to virtual acoustic space (VAS) training using virtual sound sources from headphones. Both the training methods consisted of 5-8 sessions (20 min each) of systematically presented stimuli graded according to duration and back attenuation (for real source training) or number of VAS locations (for virtual source training).Results: Results of independent t-scores comparing the spatial learning scores (pre vs. post-training) for each measure showed differences in performance between the two groups. Group II performed better than Group I on the VASI test, while the Group I out-performed Group II on the ITD. Both groups improved equally on the localization test and ILD.Conclusions: Based on the present findings, we recommend the use of VAS training as it has practical implications due to its cost effectiveness, need for minimal equipment, and end user usefulness.