http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Neat Synthesis and Anti-oxidant Activity of α-Hydroxyphosphonates
Rao, K. Uma Maheswara,Sundar, Ch. Syama,Prasad, S. Siva,Rani, C. Radha,Reddy, C. Suresh Korean Chemical Society 2011 Bulletin of the Korean Chemical Society Vol.32 No.9
A simple efficient and neat synthesis of ${\alpha}$-hydroxy phosphonates has been accomplished from aromatic/heterocyclic aldehydes and diethyl phosphite using $KHSO_4$ as a catalyst under solvent-free conditions at ambient temperature. These compounds are characterized by spectral and analytical data and tested for their anti-oxidant activity.
Applicationof MCDM Approach-TOPSISfor the Multi-Objective Optimization Problem
Ch.Maheswara Rao,K.Venkatasubbaiah 보안공학연구지원센터 2016 International Journal of Grid and Distributed Comp Vol.9 No.10
In the present work, an investigation has been made to study the effect of cutting parameters (speed, feed and depth of cut) on the multi-responses, Material Removal Rate (MRR) and Surface Roughness (Ra). The experiments were done on a conventional lathe using a tungsten carbide tool under dry environment. Twenty seven alternative combinations of speed, feed and depth of cut were considered (as per Taguchi’s standard L27 Orthogonal Array) for the machining of medium carbon steel EN8. For the optimization of multi-responses, the Multi-criteria decision making (MCDM) method, TOPSIS has been employed. Main effect plot for the Signal-to-Noise (S/N) ratios of the relative closeness coefficient (Ci+) was drawn using the MINITAB-16 software. From the TOPSIS and the main effect plot drawn for the relative closeness coefficient (Ci+), the optimal combination of the multi-responses were found at 27th alternative i.e. speed at 760 rpm, feed at 0.3 mm/rev and depth of cut at 1.5 mm respectively. The analysis of variance (ANOVA) has been done to know the influence of cutting parameters on the multi-responses. From the ANOVA results of the relative closeness coefficient (Ci+), it is found that the feed has high influence (F =41.08) followed by the depth of cut (F =25.78) and speed (F = 22.55).
Application of WSM, WPM and TOPSIS Methods for the Optimization of Multiple Responses
Ch. Maheswara Rao,K. Venkatasubbaiah 보안공학연구지원센터 2016 International Journal of Hybrid Information Techno Vol.9 No.10
Multi-criteria(or) attribute decision making (MCDM/MADM) methods have very high applications inindustriesforsolving real world engineering problems. In the present work, MCDM methods of Weighted summethod (WSM), Weighted ProductMethod (WPM) and TOPSIS, have been employed for the computational analysis of multi-responses. AA7075 has been taken as work piece for the experimentation and the experiments were done on CNC lathe as per the Taguchi’s standard L9 Orthogonal Array. The cutting parameters of speed, feed and depth of cut were taken as experimental inputs and Material Removal Rate (MRR) and Surface Roughness (Ra) were considered as responses. From the Weighted sum method (WSM) and Weighted ProductMethod (WPM) the optimal combination for multi-responses werefound at ninth alternative,i.e. speed: 2000 rpm, feed: 0.4 mm/rev and depth of cut: 0.75 mm. Similarly, from the TOPSIS results, the optimal combination for multi-responses werefound at seventh alternative,i.e. speed: 2000 rpm, feed: 0.2 mm/rev and depth of cut: 1 mm. Analysis of variance (ANOVA) has been done by using MINITAB-16 statistical software to find the influence of cutting parameters on the multi-responses. From the ANOVA results of WSM, WPM and relative closeness coefficient (Ci+), it is found that feed rate has high influence (For WSM, WPM and Ci+the F values are 60.50, 60.30 and 91.42 respectively) in affecting the multi-responses.
Experimental Investigation of Surface Roughness Characteristics Ra, Rq and Rz
Ch. Maheswara Rao,K.Venkatasubbaiah,K. Jagadeeswara Rao 보안공학연구지원센터 2016 International Journal of Hybrid Information Techno Vol.9 No.7
The challenge of modern machining industries is mainly to achieve high quality, in terms of dimensional accuracy, surface finish and high production rate. In the present work, an attempt has been made to explore the effect of EDM process parameters on various Surface Roughness characteristics Ra, Rq and Rz. The experiments have been done on medium carbon steel EN8 which has high applications in tool, oil and gas industries. For the experimentation, Pulse on time (PON), Pulse off time (POFF), Wire tension (WT) and Wire feed rate (WF) were considered as EDM inputs. Similarly, Surface roughness parameters Ra, Rq and Rz were taken as output characteristics. Taguchi’s standard L27 (3 level * 3 parameters) Orthogonal Array was used for conducting the experiments and optimization of multi responses was done by Grey analysis. From the Grey analysis, optimal combination of machining parameters for Surface Roughness characteristics was found at Pulse-on time (PON):131 μs (level 3), Pulse-off time (POFF):58 μs (level 2), Wire tension (WT):2 Kg-f (level 1) and Wire feed rate (WF):4 m/min (level 1). Analysis of variance was used to find the influence of process parameters on responses. From ANOVA of Grey Relational Grade, it is found that wire feed has high influence (F= 59.18) and pulse off time has very low influence (F= 2.50) in effecting the Surface Roughness parameters taken simultaneously. Regression models for the responses were prepared by using MINITAB-16 software. From the residual analysis, it is clear that the models prepared for the responses were more accurate, adequate and they can be used for prediction of surface roughness characteristics. Finally, the experimental and predicted values were compared and they found very close to each other.
Design of Wideband Elliptical Ring Monopole Antenna Using Characteristic Mode Analysis
Bhaskara Rao Perli,Maheswara Rao Avula 한국전자파학회JEES 2021 Journal of Electromagnetic Engineering and Science Vol.21 No.4
This paper presents the systematic design of an elliptical ring monopole wideband antenna using characteristic mode analysis. The modal analysis is used to analyze the bandwidth and the radiation performance of the radiating patch. The resonance frequencies of three characteristic modes are close to each other with similar modal current distributions and characteristic fields. These three characteristic modes are simultaneously excited by an effective feeding technique. The proposed model achieves wideband characteristics. The proposed model is printed on an inexpensive FR4 substrate with a size of 20 mm × 18 mm × 1.6 mm and has a wide impedance bandwidth of 124.4% in the range of 3.6–15.46 GHz. The prototype has been fabricated and the measured results show good agreement with simulated results. The antenna will cover WLAN, WiMAX, Wi-Fi, and X-band applications.
Neat Synthesis and Anti-oxidant Activity of α-Hydroxyphosphonates
K. Uma Maheswara Rao,C. Radha Rani,S. Siva Prasad,Ch. Syama Sundar,C. Suresh Reddy 대한화학회 2011 Bulletin of the Korean Chemical Society Vol.32 No.9
A simple efficient and neat synthesis of α-hydroxy phosphonates has been accomplished from aromatic/heterocyclic aldehydes and diethyl phosphite using KHSO_4 as a catalyst under solvent-free conditions at ambient temperature. These compounds are characterized by spectral and analytical data and tested for their anti-oxidant activity.
Synthesis of New 8-Formyl-4-methyl-7-hydroxy Coumarin Derivatives
Manidhar, D.M.,Rao, K. Uma Maheswara,Reddy, N. Bakthavatchala,Sundar, Ch. Syama,Reddy, C. Suresh Korean Chemical Society 2012 대한화학회지 Vol.56 No.4
8-Formyl-4-Methyl-7-Hydroxy Coumarin Derivatives were synthesized via Penchem condensation followed by Duffs reaction. Treatment of this with N,N-di substituted cyano acetamides in the presence of piperdine afforded New 8-Formyl-4-Methyl-7-Hydroxy Coumarin Derivatives (7a-o). Their structures were characterized by IR, $^1H$ and $^{13}C$ NMR and Mass spectral and elemental analysis data.