Multi-objective optimization of powder mixed electric discharge machining parameters for fabrication of biocompatible layer on β-Ti alloy using NSGA-II coupled with Taguchi based response surface methodology

Chander Prakash,H. K. Kansal,B. S. Pabla,Sanjeev Puri 대한기계학회 2016 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.30 No.9

The success of an implant depends upon surface characteristics like roughness, topography, chemistry and hardness. The fabrication of a hard surface in combination with micron-, submicron- and nano-scale surface roughness is a great challenge for biomanufacturing industries. The surface microhardness (MH) needs to be maximized while controlling the Surface roughness (SR). The present research is the first study in which the application of Non-dominated sorting genetic algorithm (NSGA)-II coupled with Taguchi based Response surface methodology (RSM) is used to predict the optimal conditions of Powder mixed electric discharge machining (PMEDM) parameters to fabricate the biocompatible surface on β-phase Ti alloy. Batch vial tests were first carried out in accordance with the L 25 orthogonal array. ANOVA analysis gave the significant influencing factors and then mathematical models were developed between input parameters and output responses like SR and MH using Taguchi based RSM technique. These models were then optimized using NSGA-II to obtain a set of Pareto-optimal solutions. From the series of multiple solutions, the best optimal condition to achieve required low SR and high MH was determined, which are 13 A peak current, 5 µs pulse duration, 8% duty cycle (longer pulse-interval) and 8 g/l silicon powder concentration for achieving a required low SR and high MH. The MH considerably increased about 184% compared to the base material, and about 1.02 µm SR can be achieved in combination with micron-, submicron- and nano-scale surface features.

Multidisciplinary Management of Primary Sacral Tumors: A Tertiary Care Center’s Experience and Literature Review

Chander Venugopal Sarath,Govindasamy Ramachandran,Tukkapuram Venkata Ramakrishna,Gopal Swaroop,Rudrappa Satish 대한척추외과학회 2022 Asian Spine Journal Vol.16 No.4

Sacral tumors are rare and can be benign or malignant. Their management is multifactorial and is based on the pathology, extent, and local and distant spread. Managing sacral tumors is challenging due to their proximity to visceral and neural structures. Surgical wide excision has been the standard of care for aggressive benign and malignant tumors. Our purpose was to evaluate the outcomes of a multimodal approach to managing primary sacral tumors in Sakra World Hospital, a tertiary spine care center in Bengaluru, India and perform a literature review to determine a workflow pathway. Our study was a retrospective review of patient records and included 15 patients with primary sacral tumors. Eleven surgically treated patients were evaluated clinically and radiologically and underwent biopsy before surgical excision by an all-posterior approach. A multidisciplinary approach that included intraoperative neural monitoring, plastic reconstruction, adjuvant chemotherapy, and radiotherapy was implemented whenever necessary. Sacral root preservation was attempted whenever feasible. Functional outcomes (based on the Visual Analog Scale [VAS] and Biagini scoring system) were analyzed along with disease control, with a minimum of 2 years of follow-up. The mean follow-up was 29±9.8 months. The mean VAS score significantly improved from 7.8±2.6 to 3.7±3.8 (<i>p</i> =0.026). Bowel function showed statistically significant improvement, from a mean score of 0.81±0.47 to 0.63±0.52 (<i>p</i> =0.026) at 2 years of follow-up. The mean pretreatment motor and bladder function scores were 0.53±0.31 and 0.74±0.44, respectively, improving to 0.48±0.33 and 0.68±0.56 at follow-up but without statistical significance. There was no significant loss of function, which is expected in radical sacral resections. In conclusion, primary sacral tumors require a multidisciplinary approach and management for optimal outcomes. A stand-alone posterior approach can be employed to treat most sacral lesions. <i>En-bloc</i> wide resection is the optimal treatment for primary malignant and aggressive benign tumors. Preservation of at least one functional S2 nerve root is imperative to preserve bowel and bladder function.

Capital Inflows and Capital Flight -Individual Countries Experience

( Chander Kant ) 세종대학교 경제통합연구소 1998 Journal of Economic Integration Vol.13 No.4

This paper examines whether individual countries` data show that FDI inflows facilitate capital flight and whether capital flight occurs due to poor domestic investment climate or is it due to discriminatory treatment against residents` investment. Three capital flight measures are used. Although the relationships have the expected signs, the absolute magnitude of the relationship among the countries differs widely. Also, the three measures of capital flight analyzed do not give consistent results. Thus, the definition and concept of capital flight that is actually used matters. (JEL Classifications: F23, F34, G15)

PROCEEDING OPEN NET -HARVARD BERKMAN CENTER JOINT SEMINAR ON INTERMEDIARY LIABILITY : THE ELECTRONIC SILK ROAD AND INFORMATION INTERMEDIARIES

( Anupam Chander ) 고려대학교 법학연구원 2015 Korea University Law Review Vol.18 No.-

Capatal Inflows and Capital Flight- Individual Countries Experience

Kant, Chander 세종대학교 국제경제연구소 1998 Journal of Economic Integration Vol.13 No.4

This paper examines whether individual countries' data show that FDI inflows facilitate capital flight and whether capital flight occurs due to poor domestic investment climate or is it due to discriminatory treatment against residents' investment. Three capital flight measures are used. Although the relationships have the expected signs, the absolute magnitude of the relationship among the countries differs widely. Also, the three measures of capital flight analyzed do not give consistent results. Thus, the definition and concept of capital flight that is actually used matters. (JEL Classifications: F23, F34, G15)

Weighted composition operators on Lorentz spaces

Subhash Chander Arora,Gopal Datt,Satish Verma 대한수학회 2007 대한수학회보 Vol.44 No.4

In this paper we characterize the boundedness, compactnessand closedness of the range of the weighted composition operators onLorentz spacesL(p;q), 1< p 1 , 1 q 1 .

SAFETY ASPECTS OF INTERMEDIATE HEAT TRANSPORT AND DECAY HEAT REMOVAL SYSTEMS OF SODIUM-COOLED FAST REACTORS

SUBHASH CHANDER CHETAL 한국원자력학회 2015 Nuclear Engineering and Technology Vol.47 No.3

Twenty sodium-cooled fast reactors (SFRs) have provided valuable experience in design, licensing, and operation. This paper summarizes the important safety criteria and safety guidelines of intermediate sodium systems, steam generators, decay heat removal systems and associated construction materials and in-service inspection. The safety criteria and guidelines provide a sufficient framework for design and licensing, in particular by new entrants in SFRs.

습공기선도 추가제안

Datta Chander S. 대한설비공학회 1973 설비저널 Vol.2 No.2

Pharmacological Review of Caralluma R.Br. with Special Reference to Appetite Suppression and Anti-Obesity

Harish Chander Dutt,Surjeet Singh,Bharathi Avula,Ikhlas A. Khan,Yashbir S. Bedi 한국식품영양과학회 2012 Journal of medicinal food Vol.15 No.2

Caralluma fimbriata extract has received Generally Recognized As Safe (GRAS) status for use as a nutraceutical to combat the most serious public health concern (i.e., obesity). More than 260 species grouped under the genus Caralluma (Family Apocynaceae) are distributed in tropical Asia and Mediterranean regions of the globe. Ethnobotanically,some species have been used as traditional and modern dietary ingredients to suppress appetite. Many species of Caralluma are commonly used as traditional medicine for the treatment of rheumatism, diabetes, leprosy, paralysis, and inflammation and have antimalarial, antitrypanosomal, anti-ulcer, antioxidant, antinociceptive, and antiproliferative activities. The genus is known for compounds like pregnane glycosides, flavonoid glycoside, flavones, magastigmane glycosides, pregnane steroids,steroidal glycosides, saturated and unsaturated hydrocarbons, aromatic and nonaromatic volatile compounds, and b-sitosterol. An extract of C. fimbriata (Slimaluna, Gencor Nutrients, Anaheim, CA, USA) is used as an anti-obesity agent and appetite suppressor. It is also seen that the pregnane glycosides isolated and identified from African Hoodia are reported as anti-obesity and appetite-suppressant compounds. On reviewing the studies undertaken on the chemistry, pharmacology, and therapeutic potential of Caralluma, it is concluded that the genus is also composed of pregnane glycosides as one of the major constituents. Availability of pregnane glycosides in Caralluma is an indication of the appetite-suppressant property of this genus. This coupled with the GRAS status of the extract of C. fimbriata has opened the possibility of developing an anti-obesity/appetite-suppressant product from other species of Caralluma. The main objective of this article is to review the studies undertaken on the plant in light of further research for anti-obesity drugs and nutraceuticals from species of Caralluma.

On weighted Weyl spectrum, II

Subhash Chander Arora,Preeti Dharmarha 대한수학회 2006 대한수학회보 Vol.43 No.4

In this paper, we show that ifT is a hyponormal opera-tor on a non-separable Hilbert spaceH, then Re!0(T) !0(ReT),where !0(T) is the weighted Weyl spectrum of weight with @0 h := dim H. We also give some conditions under which theproduct of two-Weyl operators is-Weyl and its converse implica-tion holds, too. Finally, we show that the weighted Weyl spectrumof a hyponormal operator satises the spectral mapping theoremfor analytic functions under certain conditions.