Browsing by Author "Chen, HH"

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A new yellow fluorescent dopant for high-efficiency organic light-emitting devices
(2006-02-21)
Wu, YS
;
Liu, TH
;
Chen, HH
;
Chen, CH
;
應用化學系
We describe the design and synthesis of a sterically hindered yellow dopant, tetra(l-butyl)rubrene (TBRb) which, when doped in either 1,4-bis[N-(1-naphthyl)-N'-phenylamino]-biphenyl or aluminum tris(8-hydroxyquinoline) (Alq(3)) as emitter, shows nearly 25% increase in luminance efficiency over that of the state-of-the-art rubrene (Rb) device without significantly effecting its corresponding color. At 5% doping in Alq3 and 20 mA/cm(2) current drive condition, the electroluminescence efficiency of TBRb reaches 8.5 cd/A and 2.8 1m/W with a yellow color of Commission Internationale de l'Eclairage chromaticity coordinates (CIEx,y)=[0.52,0.48], which is among the best ever reported for yellow electrofluorescence in organic light-emitting devices. (c) 2005 Elsevier B.V. All rights reserved.
A recursive finite element method (RFEM) for analysis of finite periodic structures in rectangular waveguides
(1996)
Chen, HH
;
Chung, SJ
;
電信工程研究所
;
Institute of Communications Engineering
A simple method for blocking parasitic modes in a waveguide-packaged microstrip-line circuit
(1998-12-01)
Chen, HH
;
Wang, CL
;
Chung, SJ
;
電信工程研究所
;
Institute of Communications Engineering
A simple structure formed by two metal patches symmetrically deposited at the two sides of the center microstrip is proposed and analyzed for blacking the higher order modes in a waveguide-packaged microstrip-line circuit. The variations (with the patch width) of the effective dielectric constants and field distributions of the modes in the packaged microstrip line with infinitely long side patches were first investigated using the two-dimensional (2-D) finite-element method (FEM) and the method of lines. The results suggested that there exists a range of patch widths at which the held distributions of the higher order modes are totally different from those of the microstrip line without side patches. The scattering of the patches as a function of the patch length and width was then studied using the three-dimensional (3-D) FEM with edge elements. It has been found that by simply choosing appropriate patch sizes, the parasitic higher order mode can be reflected without sacrificing the normal propagation of the dominant mode.
A simple method for blocking parasitic modes in a waveguide-packaged microstrip-line circuit
(1998-12-01)
Chen, HH
;
Wang, CL
;
Chung, SJ
;
電信工程研究所
;
Institute of Communications Engineering
A simple structure formed by two metal patches symmetrically deposited at the two sides of the center microstrip is proposed and analyzed for blacking the higher order modes in a waveguide-packaged microstrip-line circuit. The variations (with the patch width) of the effective dielectric constants and field distributions of the modes in the packaged microstrip line with infinitely long side patches were first investigated using the two-dimensional (2-D) finite-element method (FEM) and the method of lines. The results suggested that there exists a range of patch widths at which the held distributions of the higher order modes are totally different from those of the microstrip line without side patches. The scattering of the patches as a function of the patch length and width was then studied using the three-dimensional (3-D) FEM with edge elements. It has been found that by simply choosing appropriate patch sizes, the parasitic higher order mode can be reflected without sacrificing the normal propagation of the dominant mode.
Active cancellation of noise in a car cabin using the zero spillover controller
(2000-08-31)
Bai, MSR
;
Chen, HH
;
機械工程學系
;
Department of Mechanical Engineering
In active noise control problems, spillover will occur because of the Bode integral constraint if the performance sensors and measurement sensors are collocated, or if the control speakers and the noise sources are collocate, This paper is focused on the implementation of a multiple-channel zero-spillover ANC controller using a spatially feedforward structure for a car cabin. The plant model is realized by using a frequency-domain procedure. The linear-quadratic-Gaussian algorithm is used in controller design. Experiments are carried out to verify the proposed technique, where random noise and engine noise are chosen as the primary noise. The results indicate that the proposed controller yields a broadband attenuation for the random noise. The proposed method is also effective in attenuating the engine noise if an assumed model of the noise is incorporated into controller design. (C) 2000 Academic Press.
Analysis of a partially sealed package for microstrip-line circuits
(1998-12-01)
Chen, HH
;
Chung, SJ
;
電信工程研究所
;
Institute of Communications Engineering
A partially sealed package formed by two metal diaphragms with or without an absorber is proposed and analyzed for shielded microstrip-line circuits. The mode-matching method, method of lines, and finite-element method are mixed appropriately to investigate the package. For a specific analysis, an electric current filament and a microstrip-line gap are chosen to simulate, respectively, an active circuit element (CE) and a passive CE to be packaged. The suppression effect of the package on the spurious (higher order) modes and the influence on the dominant mode are fully studied by comparing the excitation and scattering characteristics of the CE's with and without the package.
Analytical calculation for DC inductances of rectangular spiral inductors with finite metal thickness in the PEEC formulation
(2006-02-01)
Kuo, JT
;
Su, KY
;
Liu, TY
;
Chen, HH
;
Chung, SJ
Inductances of rectangular spiral inductors with finite metal thickness are evaluated by the partial element equivalent circuit (PEEC) technique. The six fold partial self and mutual inductance integrals resulting from the PEEC partitions are found to have analytical expressions, so that the singularities of the integrands can be overcome and the theoretical or "exact" results can be obtained very efficiently. Via and underpath required for input/output connection can also be included in the calculation. Calculated inductance values for 20 square spiral inductors are checked against measured data published in open literature. Dependence of inductance values on metal thickness is investigated for two specific spiral structures.
Bifurcations and chaos in a rate gyro with harmonic excitation
(1996-07-04)
Ge, ZM
;
Chen, HH
;
機械工程學系
;
Department of Mechanical Engineering
Bifurcations and chaos in a rate gyro with harmonic excitation
(1996-07-04)
Ge, ZM
;
Chen, HH
;
交大名義發表
;
機械工程學系
;
National Chiao Tung University
Bifurcations and chaotic motions in a rate gyro with a sinusoidal velocity about the spin axis
(1997-02-20)
Ge, ZM
;
Chen, HH
;
機械工程學系
;
Department of Mechanical Engineering
An analysis is presented for a single-axis rate gyro mounted on a space vehicle undergoing sinusoidal motion and steady rotation about its spin and output axes. By varying the amplitude of sinusoidal motion, the periodic and chaotic responses of this parametrically excited non-linear system are investigated using the incremental harmonic balance (IHB) method and numerical integration. The multi-variable Floquet theory is applied to analyze the stability of periodic attractors and the behavior of bifurcations. Additionally, phase portraits, Poincare maps, average power spectra, bifurcation diagrams, parametric diagrams and Lyapunov exponents are presented to observe Hopf bifurcation, symmetry-breaking bifurcations, period-doubling bifurcations and chaotic motions. The cell mapping technique (MICM) is also used to study the basins of attraction of periodic attractors. (C) 1997 Academic Press Limited
Bifurcations and chaotic motions in a rate gyro with a sinusoidal velocity about the spin axis
(1997-02-20)
Ge, ZM
;
Chen, HH
;
交大名義發表
;
機械工程學系
;
National Chiao Tung University
An analysis is presented for a single-axis rate gyro mounted on a space vehicle undergoing sinusoidal motion and steady rotation about its spin and output axes. By varying the amplitude of sinusoidal motion, the periodic and chaotic responses of this parametrically excited non-linear system are investigated using the incremental harmonic balance (IHB) method and numerical integration. The multi-variable Floquet theory is applied to analyze the stability of periodic attractors and the behavior of bifurcations. Additionally, phase portraits, Poincare maps, average power spectra, bifurcation diagrams, parametric diagrams and Lyapunov exponents are presented to observe Hopf bifurcation, symmetry-breaking bifurcations, period-doubling bifurcations and chaotic motions. The cell mapping technique (MICM) is also used to study the basins of attraction of periodic attractors. (C) 1997 Academic Press Limited
Co-rotational finite element formulation for thin-walled beams with generic open section
(2006)
Chen, HH
;
Lin, WY
;
Hsiao, KM
;
機械工程學系
;
Department of Mechanical Engineering
A consistent co-rotational total Lagrangian finite element formulation for the geometric nonlinear buckling and postbuckling analysis of thin-walled beams with generic open section is presented. The element developed here has two nodes with seven degrees of freedom per node. The element nodes are chosen to be located at the shear centers of the end cross-sections of the beam element and the shear center axis is chosen to be the reference axis. The deformations of the beam element are described in the current element coordinate system constructed at the current configuration of the beam element. The element nodal forces are derived using the virtual work principle. The virtual rigid body motion corresponding to the virtual nodal displacements is excluded in the derivation of the element nodal forces. A procedure is proposed to determine the virtual rigid body motion. The way used to determine the element coordinate system and element nodal deformations corresponding to the virtual nodal displacements and that corresponding to the incremental nodal displacement are consistent. In element nodal forces, all coupling among bending, twisting, and stretching deformations of the beam element is considered by consistent second-order linearization of the fully geometrically nonlinear beam theory. In the derivation of the element tangent stiffness matrix, the change of element nodal forces induced by the element rigid body rotations should be considered for the present method. Thus, a stability matrix is included in the element tangent stiffness matrix. An incremental-iterative method based on the Newton-Raphson method combined with constant arc length of incremental displacement vector is employed for the solution of nonlinear equilibrium equations. The zero value of the tangent stiffness matrix determinant of the structure is used as the criterion of the buckling state. Numerical examples are presented to investigate the accuracy and efficiency of the proposed method. The effect of the terms in the element nodal force and tangent stiffness matrix, which will converge to zero with the decrease of element size, on the convergence rate of solution and accuracy for the buckling load and nonlinear behavior of three dimensional beam structures are also investigated through numerical examples. (c) 2005 Elsevier B.V. All rights reserved.
Color-saturated and highly efficient top-emitting organic light-emitting devices
(2005-05-01)
Hsu, SF
;
Lee, CC
;
Hwang, SW
;
Chen, HH
;
Chen, CH
Color-saturated and highly efficient top-emitting organic light-emitting devices (OLEDs) were developed. The device structure studied was glass/reflective silver/indium-tin oxide (ITO; 50, 75, 100, 125 and 150 nm, respectively)/organic electroluminescent (EL) stack/calcium (200 angstrom)/ silver (150 angstrom). By changing the thicknesses of ITO from 50-150 nm in the reflective ITO/Ag anode, different emissive colors from bluish green to orange can be obtained from aluminum tris(8-hydroxyquinoline) (Alq(3)) emitter. By using 2-{2-(t-butyl)-6-[(E)-2-(1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H-pyrido[3,2,1-ij]quinoline-9-yl)-1-ethenyl]-4H-4-pyranliden}malonitrile (DCJTB), 10-(1,3-benzothiazol-2-yl)- 1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H, 11H-pyrano[2,3-f]pyrido[3,2,1-ij]quinoline-11-one (C-545T) and p-bis(p-N,N-diphenyl-aminostyryl)benzene (DSA-ph) as dopants, highly saturated red, green, and blue (RGB) emissions with Commission Internationale de L'Eclairage chromaticity coordinates of (0.64, 0.36), (0.14, 0.75) and (0.14, 0.08) were obtained, respectively. (c) 2004 Elsevier B.V. All rights reserved.
Development of a multiple channel active noise cancellation system for car cabins
(2003)
Chen, HH
;
Wu, JD
;
Bai, MR
;
機械工程學系
;
Department of Mechanical Engineering
This paper describes the development of a multiple-channel active pp noise cancellation system for car cabins. Various active techniques are compared in terms of control structures and control algorithms. The filtered-x least-mean-square algorithm with synthetic reference and the linear quadratic gaussian control are employed for controller synthesis. Feedback, feedforward and hybrid configurations are adopted as the major control structures. The plant model is identified using a frequency-domain method. The controllers are implemented by using a digital signal processor. Experiments are carried out to evaluate the proposed techniques for attenuation of the internal field in a car cabin. The experimental results indicate that the hybrid control structure yields the best performance in terms of noise attenuation and convergence speed.
Doped blue emitters of 9,10-di(2-naphthyl)anthracene in organic electroluminescent devices
(2003-04-04)
Liu, TH
;
Shen, WJ
;
Yen, CK
;
Iou, CY
;
Chen, HH
Blue EL emission of 9,10-di(2-naphthyl)anthracene (ADN) based emitter in OLED is highly dependent upon its thickness and attenuated by the microcavity effect of the emitter. By carefully tuning the thickness of ADN and optimizing the doping concentration of TBP, one of the highest efficiencies reported for the anthracene based blue emitter at 6.6 cd/A with a CIE of x = 0.13; y = 0.21 is achieved.
Double degeneracy and chaos in a rate gyro with feedback control
(1998-02-05)
Ge, ZM
;
Chen, HH
;
機械工程學系
;
Department of Mechanical Engineering
The analysis of a single-axis rate gyro subjected to feedback control mounted on a space vehicle that is spinning with uncertain angular velocity omega(2) about its spin of the gyro is presented. For the autonomous case in which omega(2) is steady, we examine the dynamics of the resulting system on the center manifold near the double-zero degenerate point by using center manifold and normal form methods. There exist a few kinds of bifurcations in the autonomous case such as pitchfork and Hopf bifurcations for local bifurcation analyses, and a saddle-connection bifurcation for global analyses. As singular velocity omega(2) of the space vehicle is harmonic, the Melnikov technique was used to give criteria for the existence of chaos in the gyro motion. The numerical simulations are performed to verify the analytical results in the form of phase portraits, bifurcation diagrams and Lyapunov exponents. In addition, chaotic motions of this system can be changed into regular motions by a small parametric perturbation with Lyapunov exponent calculations. (C) 1998 Academic Press Limited.
Effect of annealing on the structural and optical properties of AgGaS2 thin films prepared by pulsed laser deposition
(2002-11-01)
Hsu, HC
;
Chen, HH
;
Kuo, SY
;
Chang, CS
;
Hsieh, WF
The influence of annealing on the AgGaS2 films groom by pulsed laser deposition has been investigated. The X-ray diffraction results show the AgGaS2 films were found with preferential orientation (1 1 2) normal to the surface and silver droplets,were diminished after the post-annealing. Photoluminescence (PL) measurements reveled the exciton energy is slightly red shifted that is possibly due to the thermal strain effect. The binding energy of the shallow, donors is similar to28 meV determined from temperature dependent PL spectra, In addition, the A-exciton and the B/C-exciton could be observed in the transmittance spectra at room temperature. (C) 2002 Elsevier Science B.V. All rights reserved.
Efficient green coumarin dopants for organic light-emitting devices
(2004-04-15)
Lee, MT
;
Yen, CK
;
Yang, WP
;
Chen, HH
;
Liao, CH
[GRAPHICS] We have synthesized a new green fluorescent dopant C-545P having incorporated five strategically placed "methyl" steric spacers on the julolidyl ring system. C-545P has good thermal properties and photostability, and when fabricated as a dopant in an Alq(3)-hosted OLED device, it shows notable improvement in luminance efficiency and is more resistant to concentration quenching than C-545T, particularly in the doping concentration range between 1 and 2% v/v, while achieving comparable device stability.
Efficient white organic light emitting devices with dual emitting layers
(2005-09-22)
Wu, YS
;
Hwang, SW
;
Chen, HH
;
Lee, MT
;
Shen, WJ
In this paper, a new white organic light-emitting device (OLED) with the structure of indium tin oxide/CFx/1,4-bis[N-(1-naphthyl)-N'-phenylamino]-biphenyl (NPB) (30 mn)NPB: 2,8-di(t-butyl)-5,11-di[4-(t-butyl)phenyl]-6,12-diphenylnaphthacene (20 nm; 1.6 %)/2-methyl-9,10-di(2-naphthyl) anthracene: p-bis(p-NN-di-phenyl-aminostyryl)benzene (40 nm, 3%)/aluminum tris(8-hydroxyquinoline) (20 nm)/LiF (1 nm)/Al (200 mn) has been investigated. The device showed white emission with a high-luminous yield of 9.75 cd/A at 20 mA/cm(2), but its Commission Internationale de l'Eclairage chromaticity coordinates appeared to change from (0.34, 0.42) at 6 mA/cm(2) to (0.27, 0.37) at 200 mA/cm(2) due to the shift of recombination zone. The change of color with drive current was suppressed by introduction of an electron-blocking layer of NPB along with a hole-blocking layer of aluminum (III) bis(2-methyl-8-quinolinato)4-phenylphenolato to the white OLED which successfully confined the recombination site and achieved a luminous yield of 9.9 cd/A at 20 mA/cm(2). (c) 2005 Elsevier B.V All rights reserved.
Estimating null values in the distributed relational databases environment
(2000-12-01)
Chen, SM
;
Chen, HH
;
資訊工程學系
;
Department of Computer Science
To estimate null values in relational database systems is an important research topic. In Chen and Yeh (1997) a method for estimating null values in relational database systems was presented. In Chen and Chen (1997) a method for fuzzy query translation for information in the distributed relational databases environment was presented. In this article, the works of Chen and Chen (1997) and Chen and Yeh (1997) are extended to propose a method for estimating null values in the distributed relational databases environment. The proposed method provides a useful way to estimate incomplete data when the relations stored in a failed server cannot be accessed in the distributed relational databases environment.