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

Additive manufacturing of metallic components – Process, structure and properties

Recent advances in friction-stir welding : Process, weldment structure and properties

Additive manufacturing (AM), widely known as 3D printing, is a method of manufacturing that forms parts from powder, wire or sheets in a process that proceeds layer by layer. Many techniques (using many different names) have been developed to accomplish this via melting or solid-state joining. In this review, these techniques for producing metal parts are explored, with a focus on the science of metal AM: processing defects, heat transfer, solidification, solid-state precipitation, mechanical properties and post-processing metallurgy. The various metal AM techniques are compared, with analysis of the strengths and limitations of each. Only a few alloys have been developed for commercial production, but recent efforts are presented as a path for the ongoing development of new materials for AM processes.

The metallurgy and processing science of metal additive manufacturing

Selective laser melting involves manufacturing of a part layer-by-layer by localised melting and solidification of metal powders. The geometry, composition, structure and property of the so...

Modelling of selective laser melting process with adaptive remeshing

Improving reliability of heat transfer and materials flow calculations during friction stir welding of dissimilar aluminum alloys

Although heat transfer and fluid flow models have provided significant insight about the welding processes and welded materials, currently they are not widely used, mainly because of two difficulties. First, the model predictions do not always agree with experiments because the values of energy absorption efficiency and other parameters cannot be prescribed from scientific principles. Second, the available models are unidirectional and cannot currently predict welding variables necessary to attain a target weld attribute. Here we provide a rigorous proof that the heat transfer and fluid flow models can be combined with an appropriate genetic algorithm (GA) to enhance reliability of computational results and achieve inverse modeling capability. The new capability enables systematic tailoring of weld attributes based on scientific principles. In particular, the GA-based optimization of arc efficiency, arc radius, effective thermal conductivity, and effective viscosity using a limited volume of experimental ...

A Genetic Algorithm-Assisted Inverse Convective Heat Transfer Model for Tailoring Weld Geometry

Joining of aluminium alloy and galvanized steel using a controlled gas metal arc process

Two wire tandem submerged arc welding (SAW-T) involves application of two electrode wires to form a single weld pool with one wire leading the other along the weld interface. Realisation of the inf...

Amitava De

Papers

Modelling of selective laser melting process with adaptive remeshing

Improving reliability of heat transfer and materials flow calculations during friction stir welding of dissimilar aluminum alloys

A Genetic Algorithm-Assisted Inverse Convective Heat Transfer Model for Tailoring Weld Geometry

Joining of aluminium alloy and galvanized steel using a controlled gas metal arc process

Probing influence of welding current on weld quality in two wire tandem submerged arc welding of HSLA steel