Browsing by Author "Tsai, TK"

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Growth and field emission of carbon nanofibers on electroless Ni-P alloy catalyst
(2003-09-01)
Tsai, TK
;
Chuang, CC
;
Chao, CG
;
Liu, WL
;
材料科學與工程學系
Carbon nanofibers (CNFs) were grown on a Ni-P alloy catalyst deposited on a silicon substrate in a microwave heating chemical vapor deposition system with methane gas at 650 degreesC. The Ni-P alloy catalyst films with various thicknesses were produced using an electroless plating nickel technique. The nanosized clusters on the clustered surface of the Ni-P alloy catalyst film directly provided the nucleation sites for CNFs without any pretreatment before the growth of the CNFs. The CNFs grown on the Ni-P alloy catalyst showed random orientation and it composed of parallel graphite planes with defects tilted from their axis. Field emission measurement indicated that the Ni-P catalyzed-CNFs exhibited excellent field emission properties. The diameter, growth rate and field emission properties show a strong correlation with the thickness of the Ni-P alloy catalyst film. (C) 2003 Elsevier Science B.V. All rights reserved.
The growth morphology and crystallinity of electroless NiP deposition on silicon
(2004-06-30)
Tsai, TK
;
Chao, CG
;
材料科學與工程學系
;
Department of Materials Science and Engineering
The growth morphology and crystallinity of the electroless NiP deposited on Si substrate pretreated by SnCl(2)/HCl and PdCl(2)/ HCl solutions is studied using transmission electron microscope (TEM), field emission scanning electron microscope (FESEM), and energy dispersive X-ray spectrum (EDS). Combining cross-sectional and surface observations show that the reaction mechanism of electroless NiP on Si is an electrochemical mechanism and the deposits are composed of a columnar structure grown along the vertical direction of the substrate surface. The phosphorus content does not have influence on the growth morphology but affects the crystallinity of the deposits. The crystallinity of the deposits is directly observed by the lattice image using high-resolution transmission electron microscope (HRTEM). The as-deposited NiP with 10.7 at.% P possesses good crystallinity and consists of Ni nanocrystal about 4-8 nm distributed randomly in the deposits. The size of nanocrystal in the deposits with 15.2 at.% P is about 2-5 nm. The deposits with 20.3 at.% P have a smaller order range and the size of nanocrystal is under 1.5 nm. The grain size decreases as the phosphorus content increases. (C) 2004 Elsevier B.V. All rights reserved.
Using knowledge-based systems for research on parallelizing compilers
(2001-03-01)
Yang, CT
;
Tseng, SS
;
Fann, YW
;
Tsai, TK
;
Hsieh, MH
The main function of parallelizing compilers is to analyze sequential programs, in particular the loop structure, to detect hidden parallelism and automatically restructure sequential programs into parallel subtasks that are executed on a multiprocessor. This article describes the design and implementation of an efficient parallelizing compiler to parallelize loops and achieve high speedup rates on multiprocessor systems. It is well known that the execution efficiency of a loop can be enhanced if the loop is executed in parallel or partially parallel, such as in a DOALL or DOACROSS loop. This article also reviews a practical parallel loop detector (PPD) that is implemented in our PFPC on finding the parallelism in loops. The PPD can extract the potential DOALL and DOACROSS loops in a program by verifying array subscripts. In addition, a new model by using knowledge-based approach is proposed to exploit more loop parallelisms in this paper. The knowledge-based approach integrates existing loop transformations and loop scheduling algorithms to make good use of their ability to extract loop parallelisms. Two rule-based systems, called the KPLT and IPLS, are then developed using repertory grid analysis and attribute-ordering tables respectively, to construct the knowledge bases. These systems can choose an appropriate transform and loop schedule, and then apply the resulting methods to perform loop parallelization and obtain a high speedup rate. For example, the IPLS system can choose an appropriate loop schedule for running on multiprocessor systems. Finally, a runtime technique based on the inspector/executor scheme is proposed in this article for finding available parallelism on loops. Our inspector can determine the wavefronts of a loop with any complex indirected array-indexing pattern by building a DEF-USE table. The inspector is fully parallel without any synchronization. Experimental results show that the new method can resolve any complex data dependence patterns where no previous research can. One of the ultimate goals is to construct a high-performance and portable FORTRAN parallelizing compiler on shared-memory multiprocessors. We believe that our research may provide more insight into the development of a highperformance parallelizing compiler Copyright (C) 2001 John Wiley & Sons, Ltd.