There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

THE DESIGN AND ANALYSIS OF EXPERIMENTS. By Oscar Kempthorne. New York, John Wiley and Sons, Inc., 1952. 631 pp. $8.50. This book by a teacher of statistics (as well as a consultant for \"experimenters\") is a comprehensive study of the philosophical background for the statistical design of experiment. It is necessary to have some facility with algebraic notation and manipulation to be able to use the volume intelligently. The problems are presented from the theoretical point of view, without such practical examples as would be helpful for those not acquainted with mathematics. The mathematical justification for the techniques is given. As a somewhat advanced treatment of the design and analysis of experiments, this volume will be interesting and helpful for many who approach statistics theoretically as well as practically. With emphasis on the \"why,\" and with description given broadly, the author relates the subject matter to the general theory of statistics and to the general problem of experimental inference. MARGARET J. ROBERTSON

The Design and Analysis of Experiments

Intermolecular And Surface Forces

Nonlinear Oscillations: Exact Solutions and their Approximations

https://pureadmin.qub.ac.uk/ws/files/126683921/Edited_sudagar_R1.pdf

Electroless nickel, alloy, composite and nano coatings – A critical review

This paper presents an experimental study of fractal characteristics of surface profile produced in Electrical Discharge Machining (EDM) and optimisation of machining parameters based on L27 Taguchi orthogonal design for tungsten carbide, mild steel and brass. Pulse current has the most significant influence in controlling fractal dimension characteristics for all the three materials. Pulse-off time has some influence in case of mild steel while pulse-on time has some influence in case of tungsten carbide. The interactions between the machining parameters also influence the fractal dimension. Optimum machining parameter combinations are identified to yield optimum (maximum) fractal dimension by Taguchi analysis.

Fractal characterisation of surface profile and optimisation in EDM using Taguchi method

Friction stir welding (FSW) is a solid-state joining process which is a relatively newer technique but has found multiple utility in various industries across the world. By employing FSW, several issues that conventional fusion welding poses, viz. distortion, low efficiency, greater heat-affected zone (HAZ), etc., can be avoided. FSW in fact for some metals gives joint efficiencies near about 100%. FSW has been highly suitable for welding metals, viz. aluminum and magnesium, which have been previously found to be highly challenging to be welded by conventional welding techniques. For this reason, FSW has been embraced by aerospace and marine industries which require welding of large aluminum panels. Joining of dissimilar metals is one of the interesting aspects that FSW is found to handle quite easily as joining occurs much below the actual melting temperature of the metals. Research is also underway for welding metals having high melting points (steel and titanium-based alloys) using FSW in an efficient manner. FSW however involves higher setup costs and thus still out of the reach of many small-scale industries which refrain from higher initial investment. Thus, cost-effective solutions to tackle this issue are continuously explored by engineers and researchers. With a concerted effort, it is likely that the true potential of FSW technique would unfold, and it’s benefits reaped by industries worldwide.

Friction Stir Welding

The present study deals with the deposition of electroless duplex and multilayer Ni–B/Ni–P coatings which are deposited on steel substrate. The characterization of the coated samples is done by the Scanning Electron Microscope (SEM) for microstructural observations. Hardness and tribological tests are carried out in micro-hardness tester and tribo-tester, respectively. The hardness, friction and wear performance of the coatings are investigated in the present study.

Deposition of Duplex and Multilayer Electroless Ni–P/Ni–B Coating and Study of Their Wear Resistance

Earlier Charpy V-notch (CVN) specimens were used to determine the nil ductility temperature (NDT) with the help of the impact test. NDT is the measure of embrittlement of material at temperature scale. CVN energy is gross energy supplied to the specimen which includes fracture energy, energy loss due to friction and inertia. So, CVN energy is not a proper characterization of fracture behavior. Thus, the determination of fracture toughness is required. Fracture toughness can be evaluated from quasi-static loading as well as dynamic loading conditions. Fatigue pre-cracked Charpy V-notch (PCVN) specimens are used to find dynamic fracture toughness. Dynamic fracture mechanics differs from quasi-static fracture mechanics in three complex features: rate-dependent material properties, the effect of inertia and reflected stress wave. To overcome the effect of inertia and stress waves, the evaluation of dynamic fracture toughness needs some special technique. In this study, two different methods are used to evaluate the dynamic fracture toughness, one is impact response curve method and another is the J-integral method. For impact response curve method, there is no time constraint present at calculation process but for the J-integral method, there is some condition regarding fracture time to be satisfied to get the valid dynamic fracture toughness data. In this work, Pre-cracked Charpy V-notch (PCVN) specimens of 20MnMoNi55 low-carbon reactor pressure vessel steel are used for impact testing in Pendulum testing machine and Drop weight machine for 7 different velocities ranging from 1 m/s to 9 m/s at cryogenic temperature (−70 °C). Calibration between the test results from the impact test on pendulum type and Drop weight test is done and found to be matching. Dynamic fracture toughness at each velocity is evaluated and compared using two different methods namely impact response curve method and J-integral method. Based on the results found, it is observed that two methods yield the same results if the time constraint referred is maintained for J-integral method.

Prasanta Sahoo

Papers

Fractal characterisation of surface profile and optimisation in EDM using Taguchi method

Friction Stir Welding

Deposition of Duplex and Multilayer Electroless Ni–P/Ni–B Coating and Study of Their Wear Resistance

Rate Dependence of Dynamic Fracture Toughness of 20MnMoNi55 Low-Carbon Steel Using Two Methods on Instrumented Drop Weight Test of PCVN

Evaluation of Friction Behavior of Electroless Ni-B Coating and its Optimization under Engine Oil Lubricated Condition