C.Y. Chan

Ultraprecision diamond turning of aluminium single crystals

Abstract Ultraprecision diamond turning is an important technology to generate a high surface finish in precision components and optics. In this paper, the diamond turning of aluminium single crystal rods with crystallographic axes normal to , and is analysed. The effect of the crystallographic anisotropy on the machining of these single crystals is investigated in the light of the mechanics of chip formation, of the cutting force and of the surface microtopography. Continuous chips were formed under all cutting conditions for all of the crystals examined. However, differently orientated crystals exhibit differences in the cutting force and in the quality of the machined surface. The implications of these findings on the improvement of the surface finish that can be obtained in the diamond turned surface are discussed.

A Hyper-Heuristic Inspired by Pearl Hunting

Pearl hunting is a traditional way of diving to retrieve pearl from pearl oysters or to hunt some other sea creatures. In some areas, hunters need to dive and search seafloor repeatedly at several meters depth for pearl oysters. In a search perspective, pearl hunting consists of repeated diversification (to surface and change target area) and intensification (to dive and find pearl oysters). A Pearl Hunter (PHunter) hyper-heuristic is inspired by the pearl hunting, as shown in Fig. 1. Given a problem domain and some low-level heuristics (LLHs), PHunter can group, test, select and organize LLHs for the domain by imitating a rational diver.

Explore the feasibility of adopting crowdsourcing for innovative problem solving

– The purpose of this paper is to explore the feasibility of adopting crowdsourcing for enhancing innovative problem solving through task design on task attributes. Task attributes have been proven to be an important factor influencing participation and engagement of crowdworkers. , – A survey questionnaire was developed and data from potential and experienced crowdworkers was collected and analyzed to identify the influence of task attributes on the quantity and quality of innovative solutions from crowds. This study finds that extrinsic and intrinsic motivation of task attributes are linked to psychological participation attention and the contribution of innovative solutions. , – It is found that crowdsourcing projects with higher awards and recognition as extrinsic motivation is positively associated with the quantity of solution. Competitive selection with performance feedback, problems with diversity of knowledge and job autonomy with more information from sponsors are positive associate with the quality of innovative solutions. These results can complement existing research studies on how task attributes influence the performance of existing crowdworkers in crowdsourcing and can also be a starting point for analyzing potential crowdworkers’ psychological perspectives. , – The novelty of this paper is that it illustrates the influential effects of five selected task attributes – monetary rewards and recognition, competitive selection, knowledge diversity, task complexity and autonomy – to enhance extrinsic and intrinsic motivation toward crowdsourcing feasibility in terms of quantity and quality of innovative solutions.

An investigation on the effect of ultra-precision machined patterns in wetting transition

This paper aims to study the influence of micro patterns on the wetting transition of a hydrophilic material. Surfaces with a designed pattern with various groove widths are machined by ultra-precision raster milling. The impact of different groove widths of the machined patterns on wetting transition will be discussed by studying the spreading of droplets on respective patterns. Contact angle and elongation length were measured using a contact angle goniometer. The present work revealed that machined surfaces on a hydrophilic material with micro patterns can achieve composite solid-liquid-air interfaces when the scales of the machined pattern fall into a critical range. The results from the experiments can provide useful information for designing self-cleaning surfaces.