On the Prediction of Grain Refinement Mechanism in Direct Chill Casting of Aluminum and Its Alloys Under Low Degree Mechanical Forced Convection

Deepak Patel,Prasenjit Biswas,Anil Kumar,Hiren R. Kotadia,Archana Mallik,Sanjeev Das 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.7

The present investigation focuses on grain refinement in pure aluminum and its alloy under mechanical stirring with a verylow degree of forced convection of 800 rpm as compared to reported values of up to 8000 rpm during direct chill castingprocess (DC). Commercially pure aluminum (99.7%) and Al6082 alloy billets were fabricated in an in-house designed DCcasting simulator. Mechanical forced convection (MFC) was applied to the melt during casting by a common four-bladedimpeller. The microstructural properties of the as-cast billets have been analysed to study the effect of MFC during casting andsolidification. The structure of both Al and its alloy is found to be refined in presence of MFC as compared to conventionalDC. A combination of simulation, experimental and theoretical approaches has been used to determine the effect of MFCin melt-temperature distribution to propose the mechanism of grain refinement. It has been observed that MFC prominentlyreduces the temperature gradient and extends undercooling time, resulting in fine grain structure.

Ground Level Ozone Variations During Weekday, Weekend and Bandha at Kathmandu Valley, Nepal

Deepak Pudasainee,Balkrishna Sapkota,Yong-Chil Seol 한국대기환경학회 2007 한국대기환경학회 학술대회논문집 Vol.- No.-

Control and Path Planning of Quadrotor UAV using Fuzzy PID

Deepak Gautam,CheolKeun Ha(하철근) 제어로봇시스템학회 2012 제어로봇시스템학회 합동학술대회 논문집 Vol.2012 No.7

This paper presents the modeling, control strategy and path planning of four-rotor vertical takeoff and landing (VTOL) unmanned air vehicle (UAV) known as Quadrotor. The UAV’s Mathematical model is derived based on Newton-Euler formulation. Motor model is included for the better approximation of system. Aerodynamic, Coriolis, and gyroscopic effect are neglected. Fuzzy-PID is proposed for the pose (position and orientation) control of the vehicle. Conventional approach of controller design is adopted where linear controller is developed based on linearized dynamics and applied to the nonlinear model. Proposed controller utilizes the fuzzy rules and reasoning to tune the PID gains over certain range. Path planning is done using Dijkstra’s algorithm. For provided initial position, destination, environment and obstacles, Dijkstra’s algorithm calculates the shortest route through given environment whilst avoiding obstacles in the path. Proposed algorithms are simulated using Matlab/Simulink environment and results are presented.

Effect of Ichnocarpus frutescens extract on antihyperglycemic, antihyperlipidemic and antioxidant status in streptozotocin-induced diabetic rats

Deepak K Dash,Tirtha Ghosh,Veerendra C Yeligar,K Murugesh,Siva S Nayak,Bhim C Maiti,Tapan K Maity 경희대학교 융합한의과학연구소 2007 Oriental Pharmacy and Experimental Medicine Vol.7 No.3

The present study was carried out to investigate the antihyperglycemic, antihyperlipidemic and antioxidant effect of chloroform and methanol extract of whole plant of Ichnocarpus frutescens (CEIF and MEIF) in streptozotocin (STZ)-induced diabetic rats. Administration of CEIF and MEIF orally at the dose of 200 mg/kg and 400 mg/kg body weight resulted in significant (P < 0.01) reduction in blood glucose levels. The body weights were significantly (P < 0.001) reduced in STZ-induced diabetic rats when compared to normal rats while the extracts significantly (P < 0.01) prevented the decrease in body weight in the CEIF and MEIF treated rats. The study was further undertaken to evaluate the antioxidant and antihyperlipidemic potential of CEIF and MEIF in STZ-induced diabetic rats. The increased levels of lipid peroxidation in the liver tissues of diabetic rats were significantly reverted back to normal levels and a significant increase in the activity of antioxidant enzymes such as superoxide dismutase, catalase and the level of reduced glutathione in the liver of diabetic rats after the treatment with CEIF and MEIF was noticed. These results clearly indicate that CEIF and MEIF exhibit significant antihyperglycemic, antihyperlipidemic and in vivo antioxidant activity in STZ-induced diabetic rats and the results were found to be in a dose dependent manner

Investigation of Thermal Conductivity and Viscosity of Al2O3/Water Nanofluids Using Full Factorial Design and Utility Concept

Deepak Khurana,Rajesh Choudhary,Sudhakar Subudhi 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2016 NANO Vol.11 No.8

In the present study, the effect of particle concentration, particle diameter and temperature on the thermal conductivity and viscosity of Al2O3/water nanofluids was investigated experimentally using design of experiment approach (full factorial design). Variables were selected at two levels each: particle concentration (0.1–1%), particle diameter (20–40 nm) and temperature (10– 40℃). It was observed that the thermal conductivity of the Al2O3/water nanofluids increases with increasing concentration and temperature and decreases with increase in particle diameter, while viscosity increases with increasing particle diameter. Results showed that the interaction effect of concentration and temperature also has significant effect on the thermal conductivity of Al2O3/water nanofluids. For viscosity, the interaction of particle diameter and temperature was important. Utility concept was used to optimize the properties collectively for better heat transfer performance. The optimal combination for high thermal conductivity and low viscosity was obtained at higher level of particle concentration (1%), lower level of particle diameter (20 nm) and higher level of temperature (40℃). At this condition the increment in thermal conductivity and viscosity compared to base fluid was 11.51% and 6.37%, respectively.

Copolymerization of cyclohexene oxide and carbon dioxide catalyzed by trinuclear Zinc complexes

Deepak Chandran,Dae-Won Park,Chang-Sik Ha,Il Kim 한국고분자학회 2006 한국고분자학회 학술대회 연구논문 초록집 Vol.2006 No.10

Hermite-Hadamard type inequality for $r_{1}$-convex function and $r_{2}$-convex function using Sugeno integrals

Deepak B. Pachpatte,Kavita U. Shinde 원광대학교 기초자연과학연구소 2017 ANNALS OF FUZZY MATHEMATICS AND INFORMATICS Vol.14 No.6

In this paper we prove a fuzzy integral inequality for $r_{1}$-convex function and $r_{2}$-convex function. Some examples satisfying results are also given.

Performance and flow characteristics of single and a novel double oscillating water column devices

Deepak Divashkar Prasad,김창구,강홍구,Mohammed Rafiuddin Ahmed,이영호 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.12

The performance of a single Oscillating water column (OWC) in normal and opposite configuration employing a Savonius rotor is investigated. For the normal OWC, the peak performance occurred at wave period T = 1.7 s with rotor speed of 86 rpm at wave height H = 80 mm. The opposite OWC recorded peak performance at the same wave period and the rotor had a maximum speed of 65 rpm at H = 80 mm. Furthermore, a novel double OWC configuration was tested and the peak performance of the rotor in the front and rear OWC occurred at T = 1.675 s with respective rotor speeds of 74 rpm and 53 rpm. The double OWC was analyzed by combining the performance of the rotor in the front and rear OWC. The Particle image velocimetry (PIV) results showed regions of re-circulating flow in the chamber as well as around the rotor. It was interesting to note that when comparing the advancing flow and the retreating flow, the flow had more energy when retreating hence suggesting more energy is imparted onto the rotor during this time. The PIV results provided a deeper insight into the flow characteristics and the rotor performance.

Enhancement of Color Images with Blue Sky Using Different Method for Sky and Non-Sky Regions

( Deepak Ghimire ),( Suresh Raj Pant ),( Joonwhoan Lee ) 한국정보처리학회 2013 한국정보처리학회 학술대회논문집 Vol.20 No.1

In this paper, we proposed a method for enhancement of color images with sky regions. The input image is converted into HSV space and then sky and non-sky regions are separated. For sky region, saturation enhancement is performed for each pixel based on the enhancement factor calculated from the average saturation of its local neighborhood. On the other hand, for the non-sky region, the enhancement is applied only on the luminance value (V) component of the HSV color image, which is performed in two steps. The luminance enhancement, which is also called as dynamic range compression, is carried out using nonlinear transfer function. Again, each pixel is further enhanced for the adjustment of the image contrast depending upon the center pixel and its neighborhood pixel values. At last, the original H and V component image and enhanced S component image for the sky region, and original H and S component image and enhanced V component image for the non-sky region are converted back to RGB image.

Detection of Sybil Attacks Using Improved AODV Protocol in Vehicular Ad Hoc Networks

Deepak Prashar,Abdirahim A. Abshir,Amandeep Nagpal 한국디지털융합학회 2020 IJICTDC Vol.5 No.1

Vehicular ad hoc network (VANET) has become most predominant on account of their usage in a vehicle to vehicle communication. But one of the major challenges in this network is the mobility of nodes involves in the communication. Either single-hop or multi-hop communication is used within the vehicle to vehicle communication. There are reactive, proactive, and hybrid routing protocols that are generally used within the multi-hop communication and for the path establishment, a reactive routing protocol named AODV is primarily used. Because of the decentralized nature of the network, there is a possibility of various attacks that reduce the performance of the network. One of the most devastating attacks is the Sybil attack which destroys the privacy of networks. This paper proposes a novel approach for the detection and isolation of the malicious nodes that are responsible for causing Sybil attack in VANETs through an improvement in the AODV protocol and thus the overall performance of the network is improved. Moreover, the proposed approach is compared with the existing one in terms of metrics like delay, packet loss, overhead, and throughput using the network simulator. Results confirmed that the proposed approach is quite effective in handling the network under the impact of a Sybil attack.