IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

Coolants and lubricants for machining can improve the machinability of the workpiece, increase productivity, and extend tool life by reducing tool wear. However, for environmental and economic reasons, recent research in industry and academia has sought ways to reduce the use of machining fluids. This paper reports the use of dry and minimum quantity lubrication (MQL) to drill austempered ductile iron (ADI), a new class of materials used for light weight automotive components like connecting rods and crankshafts. In this study, ADI is produced by a novel processing technique known as continuous casting-heat treatment process. The novel technique is developed by the integration of casting (in die casting) and heat treatment processes in the foundry to save energy and time. This paper deals with an experimental investigation on the role of MQL drilling on the cutting forces, tool wear and surface roughness of newly produced ADI at industrial speed-feed combinations by TiAlN-coated tungsten carbide tool. MQL drilling, performance is then compared with the dry and conventional drilling process under the same experimental conditions and environment. The results include significant reduction in tool wear, cutting forces and surface roughness by MQL drilling, mainly through reduction in the cutting zone temperature. © 2011 Elsevier B.V.

Department of Mechanical Engineering

World University root node

Wear

Study of dry and minimum quantity lubrication drilling of novel austempered ductile iron (ADI) for automotive applications

In this paper the anti‐friction performance of two types of coating, post‐coated coating and PVD‐TiAlN coating were investigated when drilling green austempered ductile iron (ADI) grade. The green ADI grade is produced by a new processing technology known as continuous casting‐heat treatment process. The effect of coatings on tool wear and surface finish of the holes when drilling using coolant were reported. Results showed that the tool with post‐coated coating has higher anti‐friction properties as compared to PVD‐TiAlN coating in terms of tool wear and surface roughness. Results also showed that there is a formation of preventive aluminum oxide layer during machining for both types of coating.

Conference Proceedings

Anti-friction Coating for Drilling of Green Austempered Ductile Iron (ADI) grade

This study presents the novel processing technique known as continuous casting‐heat treatment processes to produce Austempered Ductile Iron (ADI) which is a new class of ductile iron. ADI is characterized by improved mechanical properties but has low machinability as compared to other cast irons and steel of similar strength. The novel technique is developed by the integration of casting (in die casting) and heat treatment processes in foundry to save cost energy and time. Specimens just after casting were austenitized at 930° C for 90 min and then austempered in fluidized bed at 380° C for 90 and 120 min. Hence, the effect of austempering time on the morphology of retained austenite and mechanical properties of the material were examined and compared with conventionally produced ADI. Drilling tests were then carried out to evaluate the machinability of ADI in terms of cutting forces, chip micro‐hardness, chip morphology and surface roughness. The mechanical properties of ADI austempered for 120 min have found to be better as compare to the ADI austempered for 90 min.

Conference Proceedings Fa

Machinability of Austempered Ductile Iron (ADI) Produced by Integrated Green Technology of Continuous Casting-Heat Treatment Processes

The class NC 1of problems solvable by bounded fan-in circuit families of logarithmic depth is known to be contained in logarithmic space L, but not much about the converse is known. In this paper we examine the structure of classes in between NC 1 and L based on counting functions or, equivalently, based on arithmetic circuits. The classes PNC 1 and C = NC 1, defined by a test for positivity and a test for zero, respectively, of arithmetic circuit families of logarithmic depth, sit in this complexity interval. We study the landscape of Boolean hierarchies, constant-depth oracle hierarchies, and logarithmic-depth oracle hierarchies over PNC 1 and C = NC 1. We provide complete problems, obtain the upper bound L for all these hierarchies, and prove partial hierarchy collapses—in particular, the constant-depth oracle hierarchy over PNC 1 collapses to its first level PNC 1, and the constant-depth oracle hierarchy over C = NC 1 collapses to its second level.

Department of Computer Science and Engineering

International Symposium on Mathematical Foundations of Computer Science

Counting Classes and the Fine Structure between NC 1 and L

The P-complete Circuit Value Problem CVP, when restricted to monotone planar circuits MPCVP, is known to be in NC3, and for the special case of upward stratified circuits, it is known to be in LogDCFL. In this paper we re-examine the complexity of MPCVP, with special attention to circuits with cylindrical embeddings. We characterize cylindricality, which is stronger than planarity but strictly generalizes upward planarity, and make the characterization partially constructive. We use this construction, and four key reduction lemmas, to obtain several improvements. We show that stratified cylindrical monotone circuits can be evaluated in LogDCFL, and arbitrary cylindrical monotone circuits can be evaluated in AC1(LogDCFL), while monotone circuits with one-input-face planar embeddings can be evaluated in LogCFL. For monotone circuits with focused embeddings, we show an upper bound of AC1(LogDCFL). We re-examine the NC3 algorithm for general MPCVP, and note that it is in AC1(LogCFL) = SAC2. Finally, we consider extensions beyond MPCVP. We show that monotone circuits with toroidal embeddings can, given such an embedding, be evaluated in NC. Also, special kinds of arbitrary genus circuits can also be evaluated in NC. We also show that planar non-monotone circuits with polylogarithmic negation-height can be evaluated in NC.

computational complexity

Upper Bounds for Monotone Planar Circuit Value and Variants

In the uniform circuit model of computation, the width of a boolean circuit exactly characterises the “space” complexity of the computed function. Looking for a similar relationship in Valiant’s algebraic model of computation, we propose width of an arithmetic circuit as a possible measure of space. We introduce the class VL as an algebraic variant of deterministic log-space L. In the uniform setting, we show that our definition coincides with that of VPSPACE at polynomial width.Further, to define algebraic variants of non-deterministic space-bounded classes, we introduce the notion of “read-once” certificates for arithmetic circuits. We show that polynomial-size algebraic branching programs can be expressed as a read-once exponential sum over polynomials in VL, i.e. VBP∈ΣR⋅VL<math xmlns="http://www.w3.org/1998/Math/MathML"><mrow class="MJX-TeXAtom-ORD"><mi mathvariant="sans-serif">V</mi><mi mathvariant="sans-serif">B</mi><mi mathvariant="sans-serif">P</mi></mrow><mo>∈</mo><msup><mrow class="MJX-TeXAtom-ORD"><mi class="MJX-tex-mathit" mathvariant="italic">Σ</mi></mrow><mi>R</mi></msup><mo>⋅</mo><mrow class="MJX-TeXAtom-ORD"><mi mathvariant="sans-serif">V</mi><mi mathvariant="sans-serif">L</mi></mrow></math>. We also show that ΣR⋅VBP=VBP<math xmlns="http://www.w3.org/1998/Math/MathML"><msup><mrow class="MJX-TeXAtom-ORD"><mi class="MJX-tex-mathit" mathvariant="italic">Σ</mi></mrow><mi>R</mi></msup><mo>⋅</mo><mrow class="MJX-TeXAtom-ORD"><mi mathvariant="sans-serif">V</mi><mi mathvariant="sans-serif">B</mi><mi mathvariant="sans-serif">P</mi></mrow><mo>=</mo><mrow class="MJX-TeXAtom-ORD"><mi mathvariant="sans-serif">V</mi><mi mathvariant="sans-serif">B</mi><mi mathvariant="sans-serif">P</mi></mrow></math>, i.e. VBPs are stable under read-once exponential sums. Further, we show that read-once exponential sums over a restricted class of constant-width arithmetic circuits are within VQP, and this is the largest known such subclass of poly-log-width circuits with this property.