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

Dynamic contact interactions of fractal surfaces

In the present study, the effects of WC nano-particles content on the microstructure, hardness, wear, and friction behavior of aluminum matrix composites are investigated. Al-WC nano composites with varying wt% of WC (0, 1, 1.5, and 2) are fabricated using ultrasonic cavitation assisted stir-cast method. The microstructure of the nano-composite samples is analyzed using optical microscopy and scanning electron microscopy. Elemental composition is determined by energy dispersive x-ray analysis. Vicker's microhardness test is performed in different locations on the composite sample surface with a load of 50 gf and 10s dwell time. Wear and friction of the composites under dry sliding is studied using a pin-on-disk tribotester for varying normal load (10–40 N) and sliding speed (0.1–0.4 m/s). Uniform distribution of nano-WC is observed over composite surface without noticeable clustering. Reinforcement of nano-WC particles improves wear resistance and frictional behavior of the composite. Hardness is seen to increase with increase in wt% of nano-particles. Wear behavior of composites depends on formation of layers over the surface mixed with oxidized debris and counter-face particles. Wear mechanism changes from adhesion to abrasion with increase in wt% of hard nano particles.

https://iopscience.iop.org/article/10.1088/2053-1591/aab577/pdf

Tribological behavior of Al-WC nano-composites fabricated by ultrasonic cavitation assisted stir-cast method

This chapter deals with fractal dimension modelling in machining operations. The study considers the fractal dimension to describe surface roughness. Four different machining operations, including CNC end milling, CNC turning, cylindrical grinding and EDM are carried out on mild steel (AISI 1040) work-pieces. The surface roughness data are used to develop models for predicting fractal dimension using artificial neural network (ANN). From the results of all machining operations, it is seen that developed models can predict fractal dimension very accurately.

ANN modelling of fractal dimension in machining

The present study attempts to systematically assess the effect of varying the heat treatment temperature together with the duration of heat treatment on the tribological performance of EN coating and also correlating the same with the microstructural observations. High phosphorous nickel coating is developed in-house over steel substrates. The coatings are subjected to heat treatment at temperatures ranging from 200 to 800 °C for different durations (1–4 h). Suitable microstructural evaluations are carried out to study the morphology, phase structure and composition of the coatings. Hardness and friction-wear tests are carried out in a micro-hardness tester and pin-on-disc tribo-tester respectively. It is observed that heat treatment temperature as well as duration has profound impact on the microstructure of the coating. Iron diffusion and oxide formation is one of the major phenomena occurring at higher heat treatment temperatures. Hardness and wear resistance is found to increase with heat treatment. However, increased temperature (above 600 °C) and duration (4 h) is not found to have much effect on friction and wear behavior of the coating. The oxide layer formed due to high temperature gives rise to a damaged surface with cracks and delamination due to growth stresses. However, the damage is limited to the top surface of the coating which mainly comprises of oxides of nickel and iron. Hardness and wear resistance is not found to be correlated even through the dominant wear mechanism is abrasive in nature.

Correlating tribological performance with phase transformation behavior for electroless Ni-(high)P coating

In the present investigation, W 20–40wt.% Cu nanocomposite powders with average sizes ranging between 25 and 30 nm were synthesized by a soft chemical approach using tungsten hexacarbonyl [W(CO) 6 ] and copper acetonyl acetonate [Cu(acac) 2 ] as metal precursors. Particle size, morphology and distribution were measured using transmission electron microscope (TEM) and small angle X-ray scattering (SAXS). Surfactant coating on W Cu composite powders was removed on heat treatment of powders at 450 °C in hydrogen atmosphere for 1 h. Elemental analyses of as-synthesized and annealed (at 450 °C) W Cu nanocomposite powders were carried out using inductively coupled plasma-optical emission spectrometer (ICP-OES) and Leco gas analyzers. X-ray diffraction studies showed that the tungsten phase is amorphous while the crystal structure of copper phase is fcc in as-synthesized W Cu nanocomposite powders. After annealing at 700 °C peaks corresponding to bcc tungsten are observed and peaks corresponding to fcc copper become sharper. Relative densities of 98.2%, 98.8% and 99.2% were achieved for W 20wt.% Cu, W 30wt.% Cu, and W 40wt.% Cu composite powders respectively when sintered at 1000 °C.

Prasanta Sahoo

Papers

Dynamic contact interactions of fractal surfaces

Tribological behavior of Al-WC nano-composites fabricated by ultrasonic cavitation assisted stir-cast method

ANN modelling of fractal dimension in machining

Correlating tribological performance with phase transformation behavior for electroless Ni-(high)P coating

Synthesis, characterization and densification of WCu nanocomposite powders