Showing papers by "Shantanu Das published in 2022"

Individual Fairness in Feature-Based Pricing for Monopoly Markets

Abstract: We study fairness in the context of feature-based price discrimination in monopoly markets. We propose a new notion of individual fairness, namely, \alpha-fairness, which guarantees that individuals with similar features face similar prices. First, we study discrete valuation space and give an analytical solution for optimal fair feature-based pricing. We show that the cost of fair pricing is defined as the ratio of expected revenue in an optimal feature-based pricing to the expected revenue in an optimal fair feature-based pricing (CoF) can be arbitrarily large in general. When the revenue function is continuous and concave with respect to the prices, we show that one can achieve CoF strictly less than 2, irrespective of the model parameters. Finally, we provide an algorithm to compute fair feature-based pricing strategy that achieves this CoF.

Surface Preparation for Coating and Erosion MRR of SS 304 Using Silicon Carbide Abrasive Jet

Abstract: The surface preparation of shiny stainless steels is a must for applying esthetic paints, effective functional plasma spray coating, laser cladding, welding, etc., applications. The current work aims for effective surface roughening and erosion MRR of SS 304 work surface using SiC abrasive jet erosion and optimization of the process parameters. The response surface approach is used to design and conduct the studies using the Box–Behnken design method. The surface topography of the eroded surfaces is examined by a 2D profilometer, 3D profilometer, and scanning electron microscope (SEM). The abrasive grit size and working gas pressure greatly affect the surface roughness of SS 304 samples. The influence of the process parameters on the variation of these topographical features is analyzed and confirmed. The working jet pressure is seen to significantly impact erosion MRR. The lower working gas pressure shows a typical influence on Ra (surface preparation) and as pressure increases, erosion MRR rises, and the surface preparation mode shifts to the erosion metal removal/cutting zone. The quality of SS 304 surface prepared from SiC abrasive jet impact is characterized by 3D profilometry.

Space within the Space:

Abstract: In Manto’s stories about prostitutes, set in Mumbai (then Bombay), the city is presented with a kaleidoscopic projection of space. In the story, “Ten Rupees,” the volumetric space of the city, conventionally dominated by the male characters – Kishori, Kifayat, Anwar, and Shahab, is overshadowed by the abstract space created in it by the female protagonist – Sarita. Sarita, a fifteen-year-old prostitute, is presented in the story as an Object (the Other in the Subject-Other dichotomy) of men’s desire. However, she switches to the Subject position in her interactions with her customers Kifayat, Anwar, and Shahab in a car ride, and, as a matter of fact, she creates a gynocentric space of her own in the phallocentric space inside the car. In a theoretical framework drawn from both Simone de Beauvoir’s notion of the Subject-Other dichotomy, and from the prominent ideas of space in the twentieth century architectural discourses, this paper, with a qualitative method, shows how Manto portrays the character of Sarita as the Subject rather than an Object within the spaces she inhabits.

Automatic extraction of mechanical interlocking features from CAD model

Abstract: This paper represents, classifies, and automatic extracts the mechanical interlocking features (MIFs) from the CAD model. Mechanical interlocking features (MIFs) are geometric features of two or more components when physically interlock that prevent the relative movement in any or certain directions. A set of contact faces in proximity and their characteristic arrangement are used to represent the MIFs. This characteristics arrangement of contact faces and their topological relationships help in classification of MIFs. It is very difficult to manually extract the large number of MIFs from CAD models. It is therefore desirable to develop a set of algorithms to extract the MIFs from CAD model. CAD assembly models from industrial domain has been used in order to validate the proposed approach.

Performance Measure of Resistance Spot Welding of Similar and Dissimilar Triple Thin Sheets by using AHP-ANN Hybrid Network

Abstract: The analytical hierarchy process or AHP is a useful decision-making tool, and it is applied in this work in resistance spot welding where two different types of triple thin sheets consisting of aluminium, galvanized iron and stainless steel are joined. Combining both the AHP and ANN, a hybrid network is developed to eliminate the complexity of the experimental results to predict. The AHP-ANN hybrid network successfully predicted output parameters with less error. Correlation coefficient has been more than 0.98 and the applicability of this method..

A proof via polygons

Abstract: The graph bisection problem asks to partition the n vertices of a graph into two sets of equal size so that the number of edges across the cut is minimum. We study finite, connected subgraphs of the infinite twodimensional grid that do not have holes. Since bisection is an intricate problem, our interest is in the tradeoff between runtime and solution quality that we get by limiting ourselves to a special type of cut, namely cuts with at most one bend each (corner cuts). We prove that optimum corner cuts get us arbitrarily close to equal sized parts, and that this limitation makes us lose only a constant factor in the quality of the solution. We obtain our result by a thorough study of cuts in polygons and the effect of limiting these to corner cuts. 1 Comparing Optimal with Restricted Cuts We consider the bisection problem: partition the vertex set of a given graph into two (almost) equal sized subsets such that the number of edges with an endpoint in each partition is minimised. The problem has been studied extensively, due to its utility in divide-and-conquer algorithms. It is NP-hard in general [5] and the best approximation algorithm known for general graphs [9] guarantees an approximation ratio of O(log n). For planar graphs a PTAS [2] has been found, while for trees an optimum solution can be computed in O(n) time [6, 7]. Our motivation to study the bisection problem comes from the need to parallelise a finite element computation of a human bone structure model in order to diagnose osteoporosis [1]. In such an application the aim is to distribute the data, modelled by the vertices (of a graph G), evenly onto a given number p ∗We gratefully acknowledge discussions with Peter Arbenz who introduced the human bone simulation problem to us, and the support of this work through the Swiss National Science Foundation under Grant No. 200021 125201/1. †An extended abstract of this report appeared at the 37th International Workshop on Graph-Theoretic Concepts in Computer Science [4]

An Investigation on Machinability during Turning Al-Mg2Si-Si Composite in Dry Condition

Abstract: In this work, machinability study during turning of Al-Mg2Si-Si is taken into consideration with varying cutting tools. Latin square method is applied to find out the effect of cutting velocity, feed as well as insert type onto force requirement. Results show that in relatively high cutting velocity range, feed has significant effect on forces. Under 60 –75 m/min cutting velocity with 0.06-0.08 mm/rev feed, good machinability is obtained, and hence, these cutting conditions may be recommended for application in the industry.

Application of The Ahp For Optimization of Weld Strength of Al-8%Sic Composite Using Pctig Welding

Abstract: Here Analytical Hierarchical Process (AHP) was used for optimization of weld strength of Al-8%SiC composite using Pulsed Current Tungsten Inert Gas (PCTIG) welding. The experiment was designed using Taguchi L9 OA. The parameters used as criteria were pulse on time, pulse frequency, peak current, base current, peak temperature and cooling rate. The optimum condition were at peak current of 160A, base current of 60A, pulse on time of 50%, pulse frequency of 5Hz and optimum values of peak temperature and cooling rate were 446°C/s and 20°C/s respectively.