Browsing by Author "Chang, CP"

Now showing 1 - 20 of 20

A new shortest path routing algorithm and embedding cycles of crossed cube
(1997)
Chang, CP
;
Sung, TY
;
Hsu, LH
;
資訊工程學系
;
Department of Computer Science
An n-dimensional crossed cube, CQ(n), is a variation of hypercubes. In this paper, we give a new shortest path routing algorithm based on a new distance measure defined herein. In comparison with EFe's algorithm which generates one shortest path in O(n(2)) time, our algorithm can generate more shortest paths in O(n) time. Furthermore, we show that CQ(n) is a pancyclic network and we construct various types of cycles of an arbitrary length at least four.
A testing scheme for crosstalk faults based on the oscillation test signal
(2002)
Wu, MS
;
Lee, CL
;
Chang, CP
;
Chen, JE
;
電子工程學系及電子研究所
A test scheme for the crosstalk fault based on the oscillation signal is proposed. It uses an oscillation signal applied on an affecting line and detects induced pulses on a victim line if a crosstalk fault exists between these two lines. It is simple and eliminates the complicated timing issue during test generation for the crosstalk fault in the conventional approaches. The test generation and fault simulation based on the scheme are described. Experimental results are also presented to show the described test generation procedure is effective in generating test patterns for this scheme.
Characteristics of photocatalytic oxidation of gaseous 2-propanol using thin-film TiO2 photocatalyst
(2004-11-01)
Chang, CP
;
Chen, JN
;
Lu, MC
;
環境工程研究所
;
Institute of Environmental Engineering
This work presents a photocatalysis-based method to treat and purify air because of its broad applicability to common, oxidizable, air contaminants. The effect of oxygen content, temperature, water vapor, and 2-propanol concentration on the TiO2 surface was investigated. The rate of 2-propanol decomposition increased with increasing the oxygen content, but was reduced at temperatures higher than 100degreesC. When water vapor concentration was in the range of 10-355 mmol m(-3), the rate of 2-propanol decomposition was proportional to the water content. However, an opposite result was observed at a higher concentration of water vapor. 2-Propanol was photooxidized to acetone, and eventually to carbon dioxide and water. The kinetic model of 2-propanol photooxidation was successfully developed by the competitive Langmuir-Hinshelwood rate form, incorporating the inhibition effect coming from the formation of acetone. (C) 2004 Society of Chemical Industry.
Comparisons of optical properties on meta- and para-linkages of copolymers for poly(phenylene vinylene) and poly(phenylene azomethine) with alkylthio group at the side chain
(2005-02-01)
Chang, CP
;
Wang, CC
;
Chao, CY
;
Lin, MS
;
應用化學系
Three series of soluble copolymers were synthesized: I, poly[m (or p)-phenylene (diacetonitrile) vinylene-co-methoxy-5-(2'-ethylhexylthio)-p-phynylene vinylene] (m-C=C(CN), p-C=C(CN)); II, poly[m (or p)-phenylene azomethine-co-2-methoxy-5-(2'-ethylhexylthio)-p-phenylene azomethine] (m-C=N, p-C=N); III, poly[m (or p)-phenylene vinylene-co-2-methoxy-5-(2'-ethylhexythio)-p-phenyle vinylene] (m-C=C, p-C=C). Of all these copolymers, the copolymers containing meta-linkage showed glass transition temperatures (T-g's) approximately 10 degrees C to 30 degrees C lower than those of the corresponding para-linkage copolymers because of lower crystallinity. 5% weight loss of all the copolymers occurred at around 381 to 344 degrees C. Copolymers of the meta-linkage also caused a relative asymmetry and irregularity of the copolymer main chain, thus leading to a decrease of effective conjugation length and a reduction of the molecular aggregation: this subsequently led to less excimer formation. These phenomena can be evidenced from the blue-shift of PL emission, 15 to 49 nm for the meta-linkage copolymers compared with the para-linkage copolymers. In addition, due to the lesser electron-donating capability of the sulfur atom, m-C=C, p-C=C and p-C=N containing the alkylthio group indicated a blue shift of 8 to 24 nm, when compared with those copolymers of similar structures containing the alkyloxy group as reported in the literature. Since series H contains strong electron-withdrawing -C=N- at the main chain, and series I contains even stronger electron-withdrawing cyano group, thus, the observed lambda(max) are in the order: series I [m-C=C(CN), p-C=C(CN)] > series II [mC=N, p-C=N] > series III [m-C=C, p-C=C]. Furthermore, since in series II, the lone pair electrons on the -C=N- main chain would overlap partially with the six pi electrons in the phenyl ring, and decrease the coplanar nature of the main chain, thus their PL emission intensities were less than those of series I and III. Finally, a device of the structure (ITO/PEDOT: PSS/m-CC(CN)/LiF/Al) was constructed, and a yellow light of lambda(max) = 570 nm was observed.
Conditional diagnosability measures for large multiprocessor systems
(2005-02-01)
Lai, PL
;
Tan, JJM
;
Chang, CP
;
Hsu, LH
;
資訊工程學系
Diagnosability has played an important role in the reliability of an interconnection network. The classical problem of fault diagnosis is discussed widely and the diagnosability of many well-known networks have been explored. In this paper, we introduce a new measure of diagnosability, called conditional diagnosability, by restricting that any faulty set cannot contain all the neighbors of any vertex in the graph. Based on this requirement, the conditional diagnosability of the n-dimensional hypercube is shown to be 4(n - 2) + 1, which is about four times as large as the classical diagnosability. Besides, we propose some useful conditions for verifying if a system is t-diagnosable and introduce a new concept, called a strongly t-diagnosable system, under the PMC model. Applying these concepts and conditions, we investigate some t-diagnosable networks which are also strongly t-diagnosable.
Diagnosability of t-connected networks and product networks under the comparison diagnosis model
(2004-12-01)
Chang, CP
;
Lai, PL
;
Tan, JJM
;
Hsu, LH
;
資訊工程學系
Diagnosability is an important factor in measuring the reliability of an interconnection network, while the (node) connectivity is used to measure the fault tolerance of an interconnection network. We observe that there is a close relationship between the connectivity and the diagnosability. According to our results, a t-regular and t-connected network with at least 2t + 3 nodes is t-diagnosable. Furthermore, the diagnosability of the product networks is also investigated in this work. The product networks, including hypercube, mesh, and tori, comprise very important classes of interconnection networks. Herein, different combinations of t-diagnosable and t-connected are employed to study the diagnosability of the product networks.
Diagnosability of t-connected networks and product networks under the comparison diagnosis model
(2004-12-01)
Chang, CP
;
Lai, PL
;
Tan, JJM
;
Hsu, LH
;
資訊工程學系
Diagnosability is an important factor in measuring the reliability of an interconnection network, while the (node) connectivity is used to measure the fault tolerance of an interconnection network. We observe that there is a close relationship between the connectivity and the diagnosability. According to our results, a t-regular and t-connected network with at least 2t + 3 nodes is t-diagnosable. Furthermore, the diagnosability of the product networks is also investigated in this work. The product networks, including hypercube, mesh, and tori, comprise very important classes of interconnection networks. Herein, different combinations of t-diagnosable and t-connected are employed to study the diagnosability of the product networks.
Edge congestion and topological properties of crossed cubes
(2000-01-01)
Chang, CP
;
Sung, TY
;
Hsu, LH
;
資訊工程學系
;
Department of Computer Science
An n-dimensional crossed cube, CQ(n), is a variation of hypercubes. In this paper, we give a new shortest path routing algorithm based on a new distance measure defined herein. In comparison with Efe's algorithm, which generates one shortest path in O(n(2)) time, our algorithm can generate more shortest paths in O(n) time. Based on a given shortest path routing algorithm, we consider a new performance measure of interconnection networks called edge congestion. Using our shortest path routing algorithm and assuming that message exchange between all pairs of vertices is equally probable, we show that the edge congestion of crossed cubes is the same as that of hypercubes. Using the result of edge congestion, we can show that the bisection width of crossed cubes is 2(n-1). We also prove that wide diameter and fault diameter are inverted right perpendicular n/2 inverted left perpendicular + 2. Furthermore, we study embedding of cycles in cross cubes and construct more types than previous work of cycles of length at least four.
Effect of inorganic ions on the oxidation of dichlorvos insecticide with Fenton's reagent
(1997-11-01)
Lu, MC
;
Chen, JN
;
Chang, CP
;
環境工程研究所
;
Institute of Environmental Engineering
This study analyzes the oxidation of dichlorvos with Fenton's reagent in solutions containing various ions. Results show that the larger the added amount of ferrous ions, the higher the elimination rate of dichlorvos and the oxidization rate after the addition of ferric ions is far smaller than that of adding ferrous ions. Anions suppress the decomposition of dichlorvos in the following sequence: H2PO4- > > Cl- > NO3- similar to ClO4-. It can be seen that the Fenton reaction is extremely sensitive to anions, and phosphate ions in particular will seriously suppress the Fenton system's ability to oxidize dichlorvos. The main reason for the suppression of phosphate ions is that phosphate ions will produce a complex reaction together with ferrous ions and ferric ions, which then lowers its ability to catalyze hydrogen peroxide. (C) 1997 Elsevier Science Ltd.
Electron lifetime in armchair carbon nanotubes
(2004-11-01)
Chiu, CW
;
Shyu, FL
;
Chang, CP
;
Chuu, DS
;
Lin, MF
The excited conduction electrons in metallic armchair carbon nanotubes can decay by inelastic electron-electron scattering. The deexcitation channels include the single-particle and collective excitations of different angular momenta. The higher conduction subbands have more deexcitation channels, or shorter electron lifetimes. Each conduction subband has certain states with very long lifetimes, and a simple relationship between the inverse electron lifetime and the state energy is absent. Such results directly reflect the characteristics of the ID excitation spectra. The inverse electron lifetime contrasts sharply with those of semiconducting carbon nanotubes, graphite, and 2D and 3D metallic systems. Dimensionalities play an important role in the many-body effects. The predicted results could be verified by femtosecond time-resolved optical spectroscopy.
Fluorescent conjugated polymer films as TNT chemosensors
(2004-08-13)
Chang, CP
;
Chao, CY
;
Huang, JH
;
Li, AK
;
Hsu, CS
Three prototypical light emitting conjugated polymers, two poly(p-phenylene vinylenes) (MEH-PPV and DP10-PPV) and a poly(diphenylacetylene), were examined for chemosensor applications to detect explosive compounds such as 2,4,6-trinitrotoluene (TNT) and 2,4- and 2,6-dinitrotoluene (DNTs). All polymer thin films showed high fluorescence quenching sensitivity towards TNT and DNTs, indicating that a wide range of emissive conjugated polymers are potentially useful chemosensor materials for detecting landmines. The relative sensitivity of fluorescence quenching of the polymers by the analytes has been rationalized in terms of the vapor pressure of the analytes, the solubility parameters of the polymers and the analytes, and the relative energy levels of the polymers. (C) 2004 Elsevier B.V. All rights reserved.
Heterogeneous photocatalytic oxidation of acetone for air purification by near UV-irradiated titanium dioxide
(2003)
Chang, CP
;
Chen, JN
;
Lu, MC
;
環境工程研究所
;
Institute of Environmental Engineering
This work presents a photocatalysis-based method to treat and purify air because of its broad applicability to common, oxidizable air contaminants. The effect of oxygen content, temperature, water vapor, and acetone concentration on the photooxidation of acetone on TiO2 surface was investigated. The photocatalytic decomposition reaction of acetone obeyed the first-order equation. The decomposition rate increased with increasing the oxygen content. The rate of acetone oxidation increased when water vapor increased from, 18.7 to 417 muM and decreased at higher than 417 muM. The conversion and mineralization of acetone decreased at higher than 138degreesC. The initial rate of acetone degradation can be well described by the Langmuir-Hinshelwood rate form. The specific reaction rate constant and the equilibrium. adsorption are 15.8 muM/min and 0.0671 L/muM, respectively. The difference between observed and estimated half-lives became larger when the initial concentration of acetone was increased. It is assumed that the intermediates competed with parent compound so that delayed the half-life. The detection of CO2 production can support this assumption.
Magnetization of finite carbon nanotubes
(2005-05-01)
Chen, RB
;
Chang, CP
;
Hwang, JS
;
Chuu, DS
;
Lin, MF
Magnetoelectronic properties of finite carbon nanotubes (CNs) are studied for an arbitrary field direction. They are strongly affected by the nanotube geometry (length, radius; boundary structure), the magnitude and direction of the magnetic field, the Zeeman effect, and the temperature. Geometric structures determine electronic structures and magnetic properties, which thus leads to three types of energy gaps and induced magnetic fields. The critical angle, which corresponds to the change of magnetism, exists in armchair CNs, but not in zigzag CNs. It also depends on the length and the radius of CNs. Finite CNs are very different from infinite CNs. Zeeman splitting could induce complete energy-gap modulation, a drastic change in magnetization, and a gigantic paramagnetic response for all zigzag CNs. The predicted results are observable even at room temperature.
Optimal k-fault-tolerant networks for token rings
(2000-05-01)
Sung, TY
;
Ho, TY
;
Chang, CP
;
Hsu, LH
;
資訊工程學系
Fault-tolerant multiprocessors are widely used in on-line transaction processing. Fault tolerance is also desirable in massively parallel systems that have a relatively high failure probability. Two types of failures in a multiprocessor system are of interest, processor failures and link failures. Most of the previous research in designing optimal fault-tolerant topologies was concentrated on the cases that only processor failures were allowed [1, 2, 4, 6], or the cases that only link failures were allowed [3, 5, 7, 8, 11-15]. In this paper, we discuss the case of a combination of processor failures and link failures for token rings. By "k faults" we mean k-component faults in any combination of processor faults and link faults. Designing an optimal k-fault-tolerant network for token rings is equivalent to constructing an optimal k-hamiltonian graph, where k is a positive integer and corresponds to the number of faults. A graph G is k-hamiltonian if G - F is hamiltonian for any sets F subset of V boolean OR E with F less than or equal to k. An n-node k-hamiltonian graph is optimal if it contains the least number of edges among all n-node k-hamiltonian graphs. In this paper, we construct optimal k-hamiltonian graphs with k = 2 and 3, which are optimal k-fault-tolerant networks with respect to token rings.
Oxidation of dichlorvos with hydrogen peroxide using ferrous ion as catalyst
(1999-03-19)
Lu, MC
;
Chen, JN
;
Chang, CP
;
環境工程研究所
;
Institute of Environmental Engineering
This study examines how Fenton's reagent (Fe2+ and H2O2) decomposed dichlorvos insecticide. Results showed that dichlorvos decomposed in a two-stage reaction. The first stage is a Fe2+/H2O2 reaction in which dichlorvos swiftly decomposed. In the second stage, dichlorvos decomposed somewhat less rapidly, and it is a Fe3+/H2O2 reaction. The detection of ferrous ions also supports the theory of the two-stage reaction for the dichlorvos oxidation with Fenton's reagent. The dissolved oxygen of the solution decreased rapidly in the first stage reaction, but it slowly increased in the second stage with a zero-order kinetics. The Fenton system decomposed dichlorvos most rapidly when the initial pH in the solution is 3-4. In addition, increasing the concentration of hydrogen peroxide or ferrous ions can enhance the decomposition of dichlorvos. Consequently, the relationship of rate constant (k(obs)), [H2O2] and [Fe2+] at initial pH 3 is determined as k(obs) = 2.67 X 10(4)[H2O2](0.7)[Fe2+](1.2). (C) 1999 Elsevier Science B.V. All rights reserved.
Photocatalytic oxidation of gaseous DMF using thin film TiO2 photocatalyst
(2005-02-01)
Chang, CP
;
Chen, JN
;
Lu, MC
;
Yang, HY
;
環境工程研究所
The heterogeneous photocatalytic oxidation of gaseous N,N'-dimethylformamide (DMF) widely used in the manufacture of synthetic leather and synthetic textile was investigated. The experiments were carried out in a plug flow annular photoreactor coated with Degussa P-25 TiO2. The oxidation rate was dependent on DMF concentration, reaction temperature, water vapor, and oxygen content. Photocatalytic deactivation was observed in these reactions. The Levenspiel deactivation kinetic model was used to describe the decay of catalyst activity. Fourier transform infrared (FTIR) was used to characterize the surface and the deactivation mechanism of the photocatalyst. Results revealed that carbonylic acids, aldehydes, amines, carbonate and nitrate were adsorbed on the TiO2 surface during the photocatalytic reaction. The ions, NH4+ and NO3-, causing the deactivation of catalysts were detected on the TiO2 surface. Several treatment processes were applied to find a suitable procedure for the regeneration of catalytic activity. Among these procedures, the best one was found to be the H2O2/UV process. (C) 2004 Elsevier Ltd. All rights reserved.
Suppression of particle deposition in tube flow by thermophoresis
(2004-10-01)
Lin, JS
;
Tsai, CJ
;
Chang, CP
;
環境工程研究所
;
Institute of Environmental Engineering
Suppression of particle deposition from flow through a tube with circular cross-section was investigated numerically and experimentally for the case when the wall temperature exceeds that of the gas. Particle transport equations for convection, diffusion and thermophoresis were solved numerically to obtain particle concentration profiles and deposition efficiencies. The numerical results were validated by particle deposition efficiency measurements with monodisperse particles. For all particle sizes, the particle deposition efficiency was found to decrease with increasing tube wall temperature and gas flow rate. Particle deposition was suppressed completely when the tube wall was heated to a certain temperature slightly above that of the gas flow. An empirical expression has been developed to predict the dimensionless temperature difference needed for zero deposition efficiency in a laminar tube flow for a given dimensionless deposition parameter. (C) 2004 Elsevier Ltd. All rights reserved.
Temperature-dependent carrier dynamics in metallic carbon nanotubes
(2005-10-31)
Chiu, CW
;
Chiu, YH
;
Shyu, FL
;
Chang, CP
;
Chuu, DS
The low energy states in metallic armchair carbon nanotubes can decay by the electron-electron Coulomb interactions with the intraband and the interband excitations. The inelastic scattering rate is very sensitive to the changes in the electronic distribution and the state energy (or the wavevector). The temperature dependence is linear for the Fermi-momentum state. Such dependence is hardly affected by the nanotube radius and the Fermi energy. The electron-electron interactions are more efficient in electronic deexcitations compared with the electron-phonon interactions. The calculated results are roughly consistent with the experimental measurements from the time-resolved photoemission spectroscopy. (c) 2005 Elsevier B.V. All rights reserved.
The fluorescent quantum efficiency of copolymers containing coumarin-6 at the side-chain
(2005-02-01)
Cheng, JA
;
Chang, CP
;
Chen, CH
;
Lin, MS
;
應用化學系
Coumarin-6 containing acrylates (CA) with different spacers were synthesized. Copolymers of CA with methyl methacrylate (MMA) in CA/MMA in the weight ratios of 1/20, 1/40 and 1/60 were prepared by using AIBN as initiator. The copolymer compositions were determined from uv-visible spectroscopic analyses, according to Beer's law. UV absorption and photoluminescence (PL) spectra indicated a concentration quenching, which increased with increasing coumarin-6 concentration in the copolymer compositions and also increasing the spacer length from the copolymer to coumarin-6 moiety, leading to a decreased fluorescence efficiency (phi(s)/phi(o)) as well as a red shift of lambda(max). Furthermore, as the spacer, n in -(CH2)(n)-, increases from n = 2, 3 to 6, excimers formed due to overlap of chromophores, resulting in the splitting of the PL emission band and lowering the PL intensity. Experimental results revealed that when the ratio of CA/MMA = 1/60 and the spacer n = 2, the copolymer film showed an optimized fluorescent quantum efficiency.
Topological properties of twisted cube
(1999-01-01)
Chang, CP
;
Wang, JN
;
Hsu, LH
;
資訊工程學系
;
Department of Computer Science
Twisted cube, TQ(n), is derived by changing some connections of hypercube Q(n) according to specific rules. Recently, many topological properties of this variation cube are studied. In this paper, we prove that its connectivity is n, its wide diameter and fault diameter are [n/2] + 2. Furthermore, we show that TQ(n) is a pancyclic network that is cycles of an arbitrary length at least four. (C) 1999 Elsevier Science Inc. All rights reserved.