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Pan Q.-K.,Liaocheng University | Fatih Tasgetiren M.,Yasar University | Suganthan P.N.,Nanyang Technological University | Chua T.J.,Singapore Institute of Manufacturing Technology
Information Sciences | Year: 2011

In this paper, a discrete artificial bee colony (DABC) algorithm is proposed to solve the lot-streaming flow shop scheduling problem with the criterion of total weighted earliness and tardiness penalties under both the idling and no-idling cases. Unlike the original ABC algorithm, the proposed DABC algorithm represents a food source as a discrete job permutation and applies discrete operators to generate new neighboring food sources for the employed bees, onlookers and scouts. An efficient initialization scheme, which is based on the earliest due date (EDD), the smallest slack time on the last machine (LSL) and the smallest overall slack time (OSL) rules, is presented to construct the initial population with certain quality and diversity. In addition, a self adaptive strategy for generating neighboring food sources based on insert and swap operators is developed to enable the DABC algorithm to work on discrete/combinatorial spaces. Furthermore, a simple but effective local search approach is embedded in the proposed DABC algorithm to enhance the local intensification capability. Through the analysis of experimental results, the highly effective performance of the proposed DABC algorithm is shown against the best performing algorithms from the literature. © 2010 Elsevier Inc. All rights reserved. Source


Hu B.,Nanyang Technological University | Wang Q.J.,Nanyang Technological University | Zhang Y.,Singapore Institute of Manufacturing Technology
Optics Letters | Year: 2012

One-way-propagating broadly tunable terahertz plasmonic waveguide at a subwavelength scale is proposed based on a metal-dielectric-semiconductor structure. Unlike other one-way plasmonic devices that are based on interference effects of surface plasmons, the proposed one-way device is based on nonreciprocal surface magneto plasmons under an external magnetic field. Theoretical and simulation results demonstrate that the one-waypropagating frequency band can be broadly tuned by the external magnetic fields. The proposed concept can be used to realize various high performance tunable plasmonic devices such as isolators, switches and splitters for ultracompact integrated plasmonic circuits. © 2012 Optical Society of America. Source


Yu M.,Nanyang Technological University | Wang D.,Nanyang Technological University | Luo M.,Singapore Institute of Manufacturing Technology
IEEE Transactions on Industrial Electronics | Year: 2014

Prognosis of hybrid systems is a challenging problem because multiple faults may happen simultaneously at a mode where these faults have different detectabilities. In other words, at the fault-initiating mode, some of the faults are detectable while others are nondetectable. As a result, decision making based on only one observation of abnormal behavior is not reliable under this condition. This paper focuses on the development of a model-based prognosis framework for hybrid systems where a dynamic fault isolation scheme is proposed to facilitate the prognostic tasks. The degradation behavior of each faulty component is mode dependent and can be estimated by a hybrid differential evolution algorithm. Thereafter, the remaining useful life of the faulty component that varies with different operating modes is calculated by using both the estimated degradation model and the user-selected failure threshold. Experiments are carried out to validate the key concepts of the developed methods, and results suggest the effectiveness. © 1982-2012 IEEE. Source


Aramcharoen A.,Singapore Institute of Manufacturing Technology | Mativenga P.T.,University of Manchester
Journal of Cleaner Production | Year: 2014

Reducing energy demand in manufacture is an urgent challenge. This challenge is driven by higher consumer demand for manufactured products, increasing electricity and energy prices, volatility and uncertainty in energy supply and national policy. These factors, together with a need to reduce energy consumption derived carbon dioxide emissions, strategically call for energy efficient manufacturing. In manufacturing processes, especially mechanical machining, more than 90% of environmental impact arises from direct electrical energy demand in machine tools. At the machine tool level, the biggest share of the electrical energy associated with mechanical machining is required to bring the machine to a ready state and support non-cutting operations such as spindle torque requirements, auxiliary units and movements. These activities are controlled and related to machine commands such as NC codes. In this paper comprehensive information on energy intensity in machining process, including the influence of tool wear, was studied. Key energy states were identified to build up an energy demand for machining components. The paper defines the essential power constants for a database that can assist energy prediction for any available machines and workpiece materials. The assessment of alternative toolpaths identified major opportunities for energy demand reduction. © 2014 Elsevier Ltd. All rights reserved. Source


Genevet P.,Harvard University | Genevet P.,Singapore Institute of Manufacturing Technology | Capasso F.,Harvard University
Reports on Progress in Physics | Year: 2015

In this article, we review recent developments in the field of surface electromagnetic wave holography. The holography principle is used as a tool to solve an inverse engineering problem consisting of designing novel plasmonic interfaces to excite either surface waves or free-space beams with any desirable field distributions. Leveraging on the new nanotechnologies to carve subwavelength features within the large diffracting apertures of conventional holograms, it is now possible to create binary holographic interfaces to shape both amplitude phase and polarization of light. The ability of the new generation of ultrathin and compact holographic optical devices to fully address light properties could find widespread applications in photonics. © 2015 IOP Publishing Ltd. Source

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