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Your search keyword '"LIAO, T. W."' showing total 75 results
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75 results on '"LIAO, T. W."'

6. Multi-objective optimisation of multi-task scheduling in cloud manufacturing.

Author

Li, Feng, Zhang, Lin, Liao, T. W., and Liu, Yongkui

Subjects
ALGORITHMS, SETUP time, QUALITY of service, SCHEDULING, MANUFACTURING processes
Abstract

Cloud manufacturing is a consumer-centric requirement-driven manufacturing paradigm that integrates distributed resources for providing services to consumers in an on-demand manner. Scheduling of multiple tasks is an important technical means for satisfying consumer requirements in cloud manufacturing. However, high individualised requirements and the associated complex task structures complicate the task scheduling in cloud manufacturing. This paper establishes a more comprehensive model for scheduling multiple distinct tasks with complicated manufacturing processes. The hierarchical relationships (a mixture of dependency and independency) of subtasks within tasks are considered. The objectives involve three kinds of time and cost factors, namely processing time, setup time, transfer time and the respective cost. In addition, service quality is also considered into the optimisation objective. Two multi-objective-meta-heuristic algorithms, i.e. ACO-based multi-objective algorithm (MACO) and NSGA-II-based multi-objective algorithm (MGA), are designed to solve the scheduling problem. A detailed analysis of the performance of the two algorithms is performed by applying them to several different scheduling instances. Experimental results indicate that in most cases the MACO algorithm can obtain a more diverse set of Pareto solutions hence offering more alternatives to meet widely different users' needs. [ABSTRACT FROM AUTHOR]

Published
2019
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9. Unraveling the atomic structure, ripening behavior, and electronic structure of supported Au20 clusters

Author

Li, Z, Chen, H, Schouteden, K, Picot, T, Liao, T, Seliverstov, A, van Haesendonck, C, Pacchioni, G, Janssens, E, Lievens, P, Li Z., Chen H. -Y. T., Schouteden K., Picot T., Liao T. -W., Seliverstov A., van Haesendonck C., Pacchioni G., Janssens E., Lievens P., Li, Z, Chen, H, Schouteden, K, Picot, T, Liao, T, Seliverstov, A, van Haesendonck, C, Pacchioni, G, Janssens, E, Lievens, P, Li Z., Chen H. -Y. T., Schouteden K., Picot T., Liao T. -W., Seliverstov A., van Haesendonck C., Pacchioni G., Janssens E., and Lievens P.

Abstract

The free-standing Au20 cluster has a unique tetrahedral shape and a large HOMO-LUMO (highest occupied molecular orbital–lowest unoccupied molecular orbital) gap of around 1.8 electron volts. The “magic” Au20 has been intensively used as a model system for understanding the catalytic and optical properties of gold nanoclusters. However, direct real-space ground-state characterization at the atomic scale is still lacking, and obtaining fundamental information about the corresponding structural, electronic, and dynamical properties, is challenging. Here, using cluster-beam deposition and low-temperature scanning tunneling microscopy, atom-resolved topographic images and electronic spectra of supported Au20 clusters are obtained. We demonstrate that individual size-selected Au20 on ultrathin NaCl films maintains its pyramidal structure and large HOMO-LUMO gap. At higher cluster coverages, we find sintering of the clusters via Smoluchowski ripening to Au20n agglomerates. The evolution of the electron density of states deduced from the spectra reveals gap reduction with increasing agglomerate size.

Published
2020

12. Production and characterization of novel catalysts based on bimetallic deposited clusters : Productie en karakterisering van nieuwe katalysatoren gebaseerd op bimetallische gedeponeerde clusters

Author

Liao, T-W, Grandjean, D, and Lievens, P

Abstract

In order to design an ideal catalyst, the catalytic properties should be fully understood at atomic level. The well controlled nature of surface science experiments provide us an opportunity to characterize structures, electronic properties and reaction sites of the prepared nanoclusters. The unusual catalytic reactivities of small size clusters have attracted significant interests. Some of the noble metals are inert in bulk. However, they might show unusual catalytic properties as being highly dispersed. For instance, gold clusters have been demonstrated to exhibit surprisingly high catalytic activities in several reactions [1,2]. Therefore, to understanding the size effect of nanoclusters, it is important tocontrol their sizes. We propose to investigate novel catalysts based on deposited bimetallic mass-selected clusters. This investigation on thesupported mass selected clusters will be conducted in UHV systems. The cluster deposition apparatus will be utilized to produce mass-selected clusters, and they will be supported on an atomically flat oxide film, which is prepared upon metal single crystals. This single crystal will be cleaned by cycles of argon ion sputtering and subsequently annealed to form a flat surface. Cleanliness and crystallinity of the metal single crystal will be examined by STM and then exposed to oxygen at high temperature to form a uniform ordered oxide film. After that, the sample will be quenched to a selected temperature for the deposition of noble metals clusters, which will be performed by using the cluster deposition apparatus. The surface morphology of the prepared sample will be monitored byscanning tunneling microscopy (STM) and atomic force microscopy (AFM). Furthermore, X-ray diffraction (XRD), high resolution transmission electron microscope (HRTEM), and X-ray absorption spectroscopy (XAS) will be utilized to study the crystallinity and chemical composition of the prepared sample. The catalytic properties of the prepared samples will be probed with photoelectron spectroscopy (PES), Fourier transform infrared spectroscope (FTIR) and, temperature programmed desorption (TPD). In PESand FTIR experiments, they can provide the information of the species remained on the surface. Form the result of TPD, we can understand the chemisorption and chemical reactions on the sample surface. Finally, for a real industrial relevant catalyst study, the catalytic activities of clusters deposited on carbon tapes and powders in gas-flow reactors underCO (preferential) oxidation conditions will be measured. status: published

Published
2018

22. Phased Array Ultrasonic Testing for Post-Weld and OnLine Detection of Friction Stir Welding Defects.

Author

Huggett, D. J., Dewan, M. W., Wahab, M. A., Okeil, A., and Liao, T. W.

Subjects
FRICTION stir welding, CALIBRATION, PHASED array antennas, ULTRASONIC testing, RADIOGRAPHY
Abstract

Nondestructive evaluation (NDE) techniques of phased array ultrasonic testing (PAUT) and digital X-ray radiography were employed on friction stir (FS)-welded Aluminum Alloy (AA)-2219-T87 specimens. PAUT intricacies required for scanning of FS-welded specimens with a 10-MHz 32-element transducer are discussed. The time corrected gain (TCG) calibration is required for scanning with an increase in index offset to compensate for decrease in A-Scan signal peak amplitude. Calibration techniques to find small defects with appropriate size tolerances are also established. The NDE technique of digital X-ray radiography is compared to PAUT, where it was found that a calibrated PAUT system is able to discover defects less than 0.2 mm where X-ray radiography could not. Incomplete penetration (IP), wormhole (WH), surface cavity (SC), and internal void (IV) defects are analyzed. Furthermore, an online PAUT system for FSW has been developed and successfully tested. The work provided herein will provide a gateway for an ultimate goal of an automated PAUT online sensing system. [ABSTRACT FROM AUTHOR]

Published
2017
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23. Energy-Aware Material Selection for Product With Multicomponent Under Cloud Environment.

Author

Luning Bi, Ying Zuo, Fei Tao, Liao, T. W., and Zhuqing Liu

Subjects
ENERGY consumption, EMISSION control, PRODUCT design
Abstract

Energy consumption in manufacturing has risen to be a global concern. Material selection in the product design phase is of great significance to energy conservation and emission reduction. However, because of the limitation of the current life-cycle energy analysis and optimization method, such concerns have not been adequately addressed in material selection. To fill in this gap, a process to build a comprehensive multi-objective optimization model for automated multimaterial selection (MOO-MSS) on the basis of cloud manufacturing is developed in this paper. The optimizing method, named local search-differential group leader algorithm (LS-DGLA), is a hybrid of differential evolution and local search with the group leader algorithm (GLA), constructed for better flexibility to handle different needs for various product designs. Compared with a number of evolutionary algorithms and nonevolutionary algorithms, it is observed that LS-DGLA performs better in terms of speed, stability, and searching capability. [ABSTRACT FROM AUTHOR]

Published
2017
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26. Simplified Numerical Model for Rapid Design of AF Module Spring Shape Parameters

Author

Liu, D. S., Lu, C. J., Chen, S. H., Liu, C. S., and Liao, T. W.

Abstract

AbstractThe autofocusing (AF) performance of cell phone cameras is critically dependent on the design of the voice-coil motor (VCM) used to drive the lens module. Also, the metal springs in the AF module should combine high stiffness with a good actuation response and a light weight. The present study utilizes a reverse engineering approach to construct three-dimensional finite element models of the top and bottom springs in the VCM mechanism. Simulations are then performed to investigate the von Mises stress distribution and stiffness characteristics of the two springs given horizontal and vertical orientations of the AF module, respectively. In performing the simulations, the actuation force is computed using two different analysis methods, namely a simplify structure method and a coupled electromagnetic-structural method. It is shown that the simplify structure method has the advantages of a lower computational complexity and a more comprehensive modeling capability. A further series of simulations is thus to examine the effects of the spring shape parameters on the reaction force developed by the spring stiffness. The results show that the spring stiffness increases with an increasing thickness and a decreasing rib length. The simulation results obtained for different spring shape parameter settings are summarized in the form of a parameter design chart for predicting the reaction force given known values of the spring rib length and spring thickness.

Published
2018
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37. Obstruction by CO of the decomposition of methanol on Pt nanoclusters on a thin film of Al2O3/NiAl(100).

Author

Chao, C.-S., Liao, T.-W., Wang, C.X., Li, Y.-D., Hung, T.-C., and Luo, M.-F.

Subjects
*CARBON monoxide, *CHEMICAL decomposition, *METHANOL, *PLATINUM nanoparticles, *ALUMINUM oxide, *THIN films, *DEHYDROGENATION
Abstract

Highlights: [•] The obstructive effect of CO on methanol decomposition on Pt nanoclusters on the Al2O3/NiAl(100) was studied. [•] The probability of dehydrogenation of methanol was decreased by pre-adsorbed CO to half. [•] The pre-adsorbed CO obstructed less effectively the C O bond scission of methanol. [•] The produced CO with atomic hydrogen from dehydrogenated methanol exhibited a comparable effect. [ABSTRACT FROM AUTHOR]

Published
2014
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