Browsing by Issue Date, starting with "2010-09-01"

Now showing 1 - 20 of 45476

Growth and photoresponse study of PdO nanoflakes reactive-sputter deposited on SiO2
(2010-09-01)
Huang, Chien-Jung
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Pan, Fu-Ming
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Chen, Hsiu-Ying
;
Li-Chang
;
材料科學與工程學系
This study prepares PdO nanostructures on a SiO2 substrate by reactive-sputter deposition and examines photoresponse characteristics of the thin films. PdO thin films deposited at 25 degrees C is composed of bowed nanoflakes standing on the SiO2 substrate, which have a single-crystalline structure after thermal anneal at 400 degrees C. The 400 degrees C-annealed nanoflake thin film has a band gap energy in the red-light range (similar to 2.06 eV), and exhibits a very sensitive photoresponse upon the UV (365 nm) illumination. The high photoresponse sensitivity of the 400 degrees C-annealed nanoflake thin film is ascribed to a lower density of recombination centers and traps due to an excellent crystallinity and a high carrier extraction efficiency due to a low electrical resistivity. A slight decrease in the photocurrent density during the initial stage of the UV illumination is attributed to adsorption of O-2(-) anions on the 400 degrees C-annealed nanoflakes. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3476567]
Magnetic Qubit in a Non-Magnetic Semiconductor Quantum Dot Molecule
(2010-09-01)
Voskoboynikov, O.
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Wijers, C. M. J.
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交大名義發表
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National Chiao Tung University
We consider a system of two vertical lens-shaped circular InAs/GaAs quantum dots when an external magnetic field is applied along the system's growth direction. The quantum dots have substantially different diameters in contrast to most of the known systems. We discuss a possibility to coherently drive coupled electronic ground states (to relocate electronic wave functions from one dot to another). This can be described as a manipulation of a magnetic iso-spin qubit. At the same time the relocation correlates with the anti-crossing behavior of the two lowest electronic states of the quantum dot molecule and generates unusual features of the magnetic susceptibility of the system. It follows from this theoretical study that in our non-magnetic system we can perform and monitor the magnetic qubit. The qubit can be dynamically driven by an external magnetic field and retraced from the magnetic susceptibility changes. A few single-qubit quantum gates can be performed.
Brain morphological changes associated with cyclic menstrual pain
(2010-09-01)
Tu, Cheng-Hao
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Niddam, David M.
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Chao, Hsiang-Tai
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Chen, Li-Fen
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Chen, Yong-Sheng
Primary dysmenorrhea (PDM) is the most prevalent gynecological disorder for women in the reproductive age. PDM patients suffer from lower abdominal pain that starts with the onset of the menstrual flow. Prolonged nociceptive input to the central nervous system can induce functional and structural alterations throughout the nervous system. In PDM, a chronic viscero-nociceptive drive of cyclic nature, indications of central sensitization and altered brain metabolism suggest a substantial central reorganization. Previously, we hypothesized that disinhibition of orbitofrontal networks could be responsible for increased pain and negative affect in PDM. Here, we further tested this hypothesis. We used an optimized voxel-based morphometry (VBM) approach to compare total and regional gray matter (GM) increases and decreases in 32 PDM patients with 32 healthy age and menstrual cycle matched (peri-ovulatory phase) controls. Abnormal decreases were found in regions involved in pain transmission, higher level sensory processing, and affect regulation while increases were found in regions involved in pain modulation and in regulation of endocrine function. Moreover. GM changes in regions involved in top-down pain modulation and in generation of negative affect were related to the severity of the experienced PDM pain. Our results demonstrate that abnormal GM volume changes are present in PDM patients even in the absence of pain. These changes may underpin a combination of impaired pain inhibition, increased pain facilitation and increased affect. Our findings highlight that longer lasting central changes may occur not only in sustained chronic pain conditions but also in cyclic occurring pain conditions. (C) 2010 International Association for the Study of Pain. Published by Elsevier B.V. All rights reserved.
Parallel Newton-Krylov-Schwarz algorithms for the three-dimensional Poisson-Boltzmann equation in numerical simulation of colloidal particle interactions
(2010-09-01)
Hwang, Feng-Nan
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Cai, Shang-Rong
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Shao, Yun-Long
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Wu, Jong-Shinn
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機械工程學系
We investigate fully parallel Newton-Krylov-Schwarz (NKS) algorithms for solving the large sparse nonlinear systems of equations arising from the finite element discretization of the three-dimensional Poisson-Boltzmann equation (PBE), which is often used to describe the colloidal phenomena of an electric double layer around charged objects in colloidal and interfacial science. The NKS algorithm employs an inexact Newton method with backtracking (INB) as the nonlinear solver in conjunction with a Krylov subspace method as the linear solver for the corresponding Jacobian system. An overlapping Schwarz method as a preconditioner to accelerate the convergence of the linear solver. Two test cases including two isolated charged particles and two colloidal particles in a cylindrical pore are used as benchmark problems to validate the correctness of our parallel NKS-based PBE solver. In addition, a truly three-dimensional case, which models the interaction between two charged spherical particles within a rough charged micro-capillary, is simulated to demonstrate the applicability of our PBE solver to handle a problem with complex geometry. Finally, based on the result obtained from a PC cluster of parallel machines, we show numerically that NKS is quite suitable for the numerical simulation of interaction between colloidal particles, since NKS is robust in the sense that INB is able to converge within a small number of iterations regardless of the geometry, the mesh size, the number of processors. With help of an additive preconditioned Krylov subspace method NKS achieves parallel efficiency of 71% or better on up to a hundred processors for a 3D problem with 5 million unknowns. (C) 2010 Elsevier B.V. All rights reserved.
Persistent cognitive decline in older hospitalized patients in Taiwan
(2010-09-01)
Chen, Cheryl Chia-Hui
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Chang, Yue-Cune
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Huang, Guan-Hua
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Peng, Jui-Hua
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Tseng, Chien-Ning
P>Aim. This paper is a report of a study conducted to determine the prevalence and predictors of persistent and transient cognitive decline in older hospitalized patients over 6 months after hospital discharge. Background. Cognitive decline occurs in 16-35 center dot 5% of older hospitalized patients, but this decline may be persistent rather than transient. Distinguishing persistent from transient cognitive decline is clinically useful. Methods. For this prospective cohort study, 291 older patients were recruited from five medical and surgical units at a tertiary medical centre in Taiwan between 2004 and 2006. Participants were assessed for cognitive status by scores on the Mini-Mental State Examination at admission, discharge, 3 and 6 months postdischarge. Persistent cognitive decline was defined as continuing score reduction and >= 3-point reduction 6 months postdischarge. Transient decline was defined as >= 3-point reduction at some stage, with a total decline < 3 points 6 months postdischarge. Findings. The cognitive status of the majority of participants (57 center dot 4%, n = 167) decreased >= 3 points during follow-up. Of these decliners, 59 (35 center dot 3%) had persistent cognitive decline, with an average 5 center dot 32-point reduction 6 months postdischarge. Forty-six (27 center dot 5%) participants experienced transient cognitive decline. After multiple adjustments in logistic regression analysis, persistent decline was predicted by no in-hospital functional decline (OR = 0 center dot 16, P = 0 center dot 002), more re-admissions after discharge (OR = 2 center dot 42, P = 0 center dot 020), and older age (OR = 1 center dot 09, P = 0 center dot 048). Conclusion. A new perspective is needed on discharge planning on patients at risk for persistent cognitive decline. Nurses can oversee the delivery of care, identify cognitive decline, refer patients, and educate families on strategies to enhance cognitive functioning for their aging relatives.
Fuzzy decision maps: a generalization of the DEMATEL methods
(2010-09-01)
Tzeng, Gwo-Hshiung
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Chen, Wen-Hsien
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Yu, Rachung
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Shih, Meng-Lin
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科技管理研究所
The Decision making trial and evaluation laboratory (DEMATEL) method is used to build and analyze a structural model with causal relationships between different criteria. In this paper, it shows that DEMATEL is the specific case of fuzzy decision maps (FDM) when the threshold function is linear. Both FDM and DEMATEL have the same direct and indirect influence matrix. FDM incorporates the eigenvalue method, the fuzzy cognitive maps, and the weighting equation. In addition two numerical examples are illustrated to demonstrate the proposed results. On the basis of the mathematical proof and numerical results, we can conclude that FDM is a generalization of DEMATEL method.
Tailoring of the Wave Function Overlaps InAs/GaAs1-xSbx Type-II Quantum Dots
(2010-09-01)
Hsu, Wei-Ting
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Liao, Yu-An
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Lu, Shu-Kai
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Cheng, Shun-Jen
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Chiu, Pei-Chin
Effects of thermal annealing on the emission properties of type-II InAs quantum dots (QDs) covered by a thin GaAs1-xSbx layer are investigated by photoluminescence (PL) and time-resolved PL measurements. Apart from large blueshifts and a pronounced narrowing of the QD emission peak, the annealing induced alloy intermixing also leads to enhanced radiative recombination rates and reduced localized states in the GaAs1-xSbx layer. We find that the type-II QD structure can sustain thermal annealing up, to 850 degrees C. In particular, we find that it is possible to manipulate between type-I and type-II recombinations in annealed QDs by using different excitation powers. We demonstrate that postgrowth thermal annealing can be used to tailor the band alignment, the wave function overlaps, and hence the recombination dynamics in the InAs/GaAs1-xSbx type-II QDs. (C) 2009 Elsevier B.V. All rights reserved.
Flip-Chip-Based Multichip Module for Low Phase-Noise V-Band Frequency Generation
(2010-09-01)
Hsu, Li-Han
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Kuylenstierna, Dan
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Kozhuharov, Rumen
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Gavell, Marcus
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Karnfelt, Camilla
This paper reports on a flip-chip (FC)-based multichip module (MCM) for low phase-noise (PN) V -band frequency generation. A high-performance x8 GaAs metamorphic high-electron mobility transistor monolithic microwave integrated circuit (MMIC) multiplier and a low PN 7-GHz GaAs InGaP heterojunction bipolar transistor (HBT) MMIC oscillator were used in the module. The microstrip MMICs were FC bonded to an Al(2)O(3) carrier with patterns optimized for low-loss transitions. The FC-based module was experimentally characterized to have a PN of -88 dBe/Hz @ 100-kHz offset and -112 dBc/Hz @ 1-MHz offset with an output power of 11 dBm. For comparison, the MMICs were also FC bonded as individual chips and the performance was compared with the bare dies without FC bonding. It was verified that the FC bonding has no detrimental effect on the MMIC performance. The tests revealed that the FC module provided improved performance. To our best knowledge, this is the first FC-based module for millimeter-wave frequency generation. The module also presents one of the best PN reported for millimeter-wave frequency sources.
EFFICIENT CONVERTIBLE MULTI-AUTHENTICATED ENCRYPTION SCHEME WITHOUT MESSAGE REDUNDANCY OR ONE-WAY HASH FUNCTION
(2010-09-01)
Tsai, Jia-Lun
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Wu, Tzong-Sun
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Lin, Han-Yu
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Lee, Jong-Eao
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應用數學系
A convertible multi-authenticated encryption (CMAE) scheme providing confidentiality, authenticity and non-repudiation properties allows a designated recipient to recover and verify an authenticated message which is signed by multiple signers. The recipient has the ability to further prove the dishonesty of signers to any third party if they repudiate their signature latter. In 2008, Wu et al. first proposed a CMAE scheme based on. discrete logarithms, but the computational complexity of their scheme is rather high and the message redundancy is required. To improve the performance and remove the message redundancy, Tsai adopted one-way hash functions (such as MD5) to propose a new scheme. In 2005, however, MD5 was cracked by Wang and Yu, which indicates that the schemes using one-way hash functions might turn out to be vulnerable to such an attack. This paper proposes a new efficient CMAE scheme. Neither the one-way hash, function nor the message redundancy is employed in the proposed scheme. The scheme not only preserves the advantages of Wu et al. 's, but also outperforms their scheme. With low computational cost, our proposed scheme can be practically implemented.
When technology speaks language: an evaluation of course management systems used in a language learning context
(2010-09-01)
Yu, Wen-Kai
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Sun, Yu-Chih
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Chang, Yu-Jung
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英語教學研究所
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Institute of Teaching English to speakers of other Languages
In light of the growing popularity of the use of computer management systems (CMSs) in higher education today, this study critically evaluates CMS adoption through a content-specific lens. By employing a mixed-method approach, the study examines college teachers' and students' experiences and perceptions of CMS adoption for language learning and teaching purposes. The findings show that despite the users' perceived advantages of using CMSs in language courses, the systems' lack of content-area specificity undermines many of the potential benefits. The study calls for better-rounded professional training to assist language teachers in integrating CMS functions strategically into their disciplinary pedagogy and incorporating multimedia language resources selectively to maximize the benefit of CMSs. Furthermore, the findings demonstrate the importance of developing content-specific CMSs with functions tailored toward pedagogical needs in different contexts.
Farce, Pathos, and Absurdity in Stephen Chow's Film Comedies: From Beijing with Love and CJ7 Reconsidered
(2010-09-01)
Yu, Eric K. W.
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外國語文學系
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Department of Foreign Languages and Literatures
The hugely popular Hong Kong film comedian and director Stephen Chow Sing Chi enjoyed international box-office success as well as critical acclaim for his Kung Fu Hustle (2004). Despite its lukewarm reception in the West, his latest film CJ7 (2008) has been compared to Charlie Chaplin's classic The Kid (1921). This paper explores the seldom-discussed Chaplinesque aspect in Chow's oeuvre, arguing that how to evoke pathos while preserving the funniest ingredients of farce has in fact been an artistic obsession for Chow for years. Focusing on Chow's early work From Beijing with Love (1994), a daring blend of farce and pathos, and CJ7, his latest endeavor to "seek joy amidst sorrow," this paper examines Chow's major comic devices, including the significance of absurdity created by situational humor, and probes into the curious interaction between low comedy elements and narrative techniques which elicit emotional responses beyond belly laughs. How can pathos be created in a generally low comic climate without appearing to be playful insincerity? How can pathos so created be prevented from developing into sentimentality, an easy target for burlesque? Such are the questions in film aesthetics addressed by the present study. Attending to the dissimilar reception of CJ7 in Greater China and the West, this paper also seeks to explore how cultural differences might have complicated Chow's recent attempts to cater his works for a more global audience.
Investigation of bubble effect in microfluidic fuel cells by a simplified microfluidic reactor
(2010-09-01)
Shyu, Jin-Cherng
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Wei, Chung-Sheng
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Lee, Ching-Jiun
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Wang, Chi-Chuan
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機械工程學系
This study experimentally examines the influence of two-phase flow on the fluid flow in membraneless microfluidic fuel cells. The gas production rate from such fuel cell is firstly estimated via corresponding electrochemical equations and stoichiometry from the published measured current-voltage curves in the literature to identify the existence of gas bubble. It is observed that O(2) bubble is likely to be generated in Hasegawa's experiment when the current density exceeds 30 mA cm(-2) and 3 mA cm(-2) for volumetric flow rates of 100 mu L min(-1) and 10 mu L min(-1), respectively. Besides, CO(2) bubble is also likely to be presented in the Jayashree's experiment at a current density above 110 mA cm(-2) at their operating volumetric liquid flow rate, 0.3 mL min(-1). Secondly, a 1000-mu m-width and 50-mu m-depth platinum-deposited microfluidic reactor is fabricated and tested to estimate the gas bubble effect on the mixing in the similar microchannel at different volumetric flow rates. Analysis of the mixing along with the flow visualization confirm that the membraneless fuel cell should be free from any bubble, since the mixing index of the two inlet streams with bubble generation is almost five times higher than that without any bubble at the downstream. (C) 2010 Elsevier Ltd. All rights reserved.
An Extreme Surface Proximity Push for Embedded SiGe in pMOSFETs Featuring Self-Aligned Silicon Reflow
(2010-09-01)
Lin, Da-Wen
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Chen, Chien-Liang
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Chen, Ming-Jer
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Wu, Chung-Cheng
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電子工程學系及電子研究所
This letter proposes a novel process to modulate the distance, or proximity, between the tip of embedded silicon-germanium (e-SiGe) and the channel region in pMOSFETs. Traditionally, sophisticated etching treatment is adopted in a spacer structure; however, process-induced variation in the e-SiGe proximity may lead to serious variation in pMOSFET performance. In this letter, an extremely close proximity is achieved using self-aligned silicon reflow (SASR) in hydrogen ambient. As opposed to conventional approaches which have e-SiGe proximity determined by spacer width, the tip of e-SiGe with SASR can be positioned flush with the gate edge, as corroborated by both the TEM analyses and TCAD simulation. A significant improvement in pMOSFET performance is also measured.
Strategy of global asset allocation using extended classifier system
(2010-09-01)
Tsai, Wen-Chih
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Chen, An-Pin
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資訊管理與財務金融系註：原資管所+財金所
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Department of Information Management and Finance
There are several studies about extended classification system (XCS) in past years. XCS model can dynamically learn and adapt to the change of environments for maximizing the desired goals. This paper conducts simulation to apply XCS to global asset allocation in the country-specific exchanged traded funds (ETFs). Since international stock price trend is influenced by unknown and unpredictable surroundings, using XCS to model the fluctuations on global financial market allows for the discovery of the patterns of the future trends. As such, the benefits of international asset diversification can be achieved in a tax-efficient way with country-specific ETFs at a low transaction cost with minimized tracking error. These empirical results indicate that XCS is capable of evolving over time, and thus XCS can provide a good indicator for future global asset allocation decision-making aiming at maximized profit. (C) 2010 Elsevier Ltd. All rights reserved.
THE INCREMENTAL VALUE OF A FUTURES HEDGE USING REALIZED VOLATILITY
(2010-09-01)
Lai, Yu-Sheng
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Sheu, Her-Jiun
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管理科學系
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Department of Management Science
A number of prior studies have developed a variety of multivariate volatility models to describe the joint distribution of spot and futures, and have applied the results to form the optimal futures hedge. In this study, the authors propose a new class of multivariate volatility models encompassing realized volatility (RV) estimates to estimate the risk-minimizing hedge ratio, and compare the hedging performance of the proposed models with those generated by return-based models. In an out-of-sample context with a daily rebalancing approach, based on an extensive set of statistical and economic performance measures, the empirical results show that improvement can be substantial when switching from daily to intraday. This essentially comes from the advantage that the intraday-based RV potentially can provide more accurate daily covariance matrix estimates than RV utilizing daily prices. Finally, this study also analyzes the effect of hedge horizon on hedge ratio and hedging effectiveness for both the in-sample and the out-of-sample data. (C) 2009 Wiley Periodicals, Inc. Jrl Fut Mark 30:874-896,2010
Structural and Optical Properties of Novel In2O3 Nanoparticle-Assembled Nanorods
(2010-09-01)
Lai, Hsiang-Yu
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Chen, Chun-Hua
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Lee, Chi-Feng
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材料科學與工程學系
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Department of Materials Science and Engineering
In2O3 nanoparticle-assembled nanorods with distinct surface morphologies have been newly synthesized by a dehydration process of self-assembled In(OH)(3) nanorods obtained from a liquid-based route. The reaction mechanism and the structural transformation between these two one-dimensional nanorods, In2O3 and In(OH)(3), were precisely characterized by means of various qualitative and quantitative analyses with X-ray scattering simulations. The broad absorption band in the UV-visible spectrum evidently originates from the nanoparticle-assembling effect within the In2O3 nanorods. An intensive photoluminescence emission at 440 nm observed under an excitation wavelength of 325 nm is attributed to the existence of oxygen vacancies within the In2O3 nanorods.
A water flow-like algorithm for manufacturing cell formation problems
(2010-09-01)
Wu, Tai-Hsi
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Chung, Shu-Hsing
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Chang, Chin-Chih
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工業工程與管理學系
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Department of Industrial Engineering and Management
Available research on the manufacturing cell formation problem shows that most solution approaches are either single- or multiple-solution-agent-based, with a fixed size of solution agents. Frequent problems encountered during the process of solving the cell formation problem include solutions being easily trapped in local optima and bad solution efficiency. Yang and Wang [Yang, F.-C., Wang, Y.-P., 2007. Water flow-like algorithm for object grouping problems. journal of the Chinese Institute of Industrial Engineers, 24(6). 475-488] proposed the water flow-like algorithm (WFA) to overcome the shortcomings of single- and multiple-solution-agent-based algorithms. WFA has the features of multiple and dynamic numbers of solution agents, and its mimicking of the natural behavior of water flowing from higher to lower levels coincides exactly with the process of searching for optimal solutions. This paper therefore adopts the WFA logic and designs a heuristic algorithm for solving the cell formation problem. Computational results obtained from running a set of 37 test instances from the literature and newly created have shown that the proposed algorithm has performed better than other benchmarking approaches both in solution effectiveness and efficiency, especially in large-sized problems. The superiority of the proposed WFACF over other approaches from the literature should be attributed to the collaboration of the WFA logic, the proposed prior estimation of the cell size, and the insertion-move. The WFA is a novel heuristic approach that deserves more attention. More attempts on adopting the WFA logic to solve many other combinatorial optimization problems are highly recommended. (C) 2010 Elsevier B.V. All rights reserved.
Study of ultra-shallow p(+)n junctions formed by excimer laser annealing
(2010-09-01)
Juang, Miin-Horng
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Lu, C. N.
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Jang, S. L.
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Cheng, H. C.
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電子工程學系及電子研究所
Excellent ultra-shallow p(+)n junctions have been formed by thermally treating the BF(2)(+)-implanted Si samples by excimer laser annealing (ELA) at 300-400 rnJ cm(-2) with post low-temperature long-time furnace annealing (FA) at 600 degrees C. A junction with a leakage current density lower than 20 nA cm(-2) and a sheet resistance smaller than 200 Omega square(-1) can be well achieved. No considerable dopant diffusion is observed by using this low-thermal-budget annealing process. However, by simply using the ELA treatment at 300-400 mJ cm(-2), the resultant junction shows a leakage current density as high as 10(4) nA cm(-2) and a peripheral leakage current density of 10(3) nA cm(-1). The large junction leakage is primarily due to the leakage current generated within the junction region near the local-oxidation-of-silicon (LOCOS) edge, and which is substantially caused by the ELA treatment. The large peripheral junction leakage current density can be significantly reduced to be about 0.2 nA cm(-1) after a post low-temperature FA treatment at 600 degrees C. As a result, the scheme that employs ELA treatment with post low-temperature FA treatment would be efficient for forming excellent ultra-shallow p(+)n junctions at low thermal budget. (C) 2010 Elsevier BM. All rights reserved.
Effects of ambient illuminance and electronic displays on users' visual performance for young and elderly users
(2010-09-01)
Wang, An-Hsiang
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Hwang, Su-Lun
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Kuo, Hui-Tzu
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Jeng, Shie-Chang
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影像與生醫光電研究所
This study investigated the effects of age (young participants aged 20-30 and elderly participants older than 60), ambient illuminance (50, 500, 1500, 3000, 6000, and 9000 lx) on participants' visual performance when using various electronic displays (conventional transmissive LCD, Ch-LC display, and E-ink display). Overall, the results indicated that participants' visual performance showed significant difference among various ambient illuminance conditions, electronic displays, and between two groups of participants. Significantly different visual performance was observed between young and elderly participants. The interaction among ambient illuminance, type of electronic display, and age had a significant effect on participants' visual performance. When participants used the E-ink display, both young and elderly participants had significantly worse visual performance under an ambient illuminance of 50 lx compared to other illuminance settings. When participants used the Ch-LC display, young participants had significantly worse visual performance under an ambient illuminance of 50 lx compared to other illuminance settings, but elderly participants had significantly better visual performance under an ambient illuminance higher than 1500 lx. When young participants used a conventional transmissive LCD, the ambient illuminance had no significant effect on their visual performance. When elderly participants use a conventional transmissive LCD, an illuminance of 50 and 6000 lx seem to have a detrimental effect on their visual performance.
Modeling Corporate Citizenship and Its Relationship with Organizational Citizenship Behaviors
(2010-09-01)
Lin, Chieh-Peng
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Lyau, Nyan-Myau
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Tsai, Yuan-Hui
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Chen, Wen-Yung
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Chiu, Chou-Kang
Citizenship, such as corporate citizenship and organizational citizenship, has been an important issue in business management for decades. This study proposes a research model from the perspectives of social identity and resource allocation, by examining the influence of corporate citizenship on organizational citizenship behaviors (OCBs). In the model, OCBs are positively influenced by perceived legal citizenship and perceived ethical citizenship, while negatively influenced by perceived discretionary citizenship. Empirical testing using a survey of personnel from 18 large firms confirms most of our hypothesized effects. Theoretical and managerial implications of our findings are discussed.