Browsing by Issue Date, starting with "2016-09-26"

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Confirmation of filament dissolution behavior by analyzing electrical field effect during reset process in oxide-based RRAM
(2016-09-26)
Pan, Chih-Hung
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Chang, Ting-Chang
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Tsai, Tsung-Ming
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Chang, Kuan-Chang
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Chu, Tian-Jian
In this letter, we demonstrate completely different characteristics with different operating modes and analyze the electrical field effect to confirm the filament dissolution behavior. The device exhibited a larger memory window when using a single voltage sweep method during reset process rather than the traditional double sweep method. The phenomenon was verified by using fast I-V measurement to simulate the two operating methods. A better high resistance state (HRS) will be obtained with a very short rising time pulse, but quite notably, lower power consumption was needed. We proposed the electrical field effect to explain the phenomenon and demonstrate distribution by COMSOL simulation. Published by AIP Publishing.
Self-adjusting feature maps network and its applications
(2016-09-26)
Li, Dong-Lin
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Prasad, Mukesh
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Lin, Chin-Teng
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Chang, Jyh-Yeong
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資訊工程學系
This paper, proposes a novel artificial neural network, called self-adjusting feature map (SAM), and develop its unsupervised learning ability with self-adjusting mechanism. The trained network structure of representative connected neurons not only displays the spatial relation of the input data distribution but also quantizes the data well. The SAM can automatically isolate a set of connected neurons, in which, the used number of the sets may indicate the number of clusters. The idea of self-adjusting mechanism is based on combining of mathematical statistics and neurological advantages and retreat of waste. In the training process,, for each representative neuron has are three phases, growth, adaptation and decline. The network of representative neurons, first create the necessary neurons according to the local density of the input data in the growth phase. In the adaption phase, it adjusts neighborhood neuron pair\'s connected/disconnected topology constantly according to the statistics of input feature data. Finally, the unnecessary neurons of the network are merged or remove in the decline phase. In this paper, we exploit the SAM to handle some peculiar cases that cannot be handled easily by classical unsupervised learning networks such as self-organizing map (SOM) network. The remarkable characteristics of the SAM can be seen on various real world cases in the experimental results. (C) 2016 Elsevier B.V. All rights reserved.
Effects on Organic Photovoltaics Using Femtosecond-Laser-Treated Indium Tin Oxides
(2016-09-28)
Chen, Mei-Hsin
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Tseng, Ya-Hsin
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Chao, Yi-Ping
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Tseng, Sheng-Yang
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Lin, Zong-Rong
The effects of, femtosecond-laser-induced periodic surface structures (LIPSS) on an indium tin oxide (ITO) surface applied to an organic photovoltaic (OPV), system were investigated. The modifications of ITO induced by LIPPS in OPV devices result in more than 14% increase in power conversion efficiency (PCE) and short-circuit current density relative to-those of the standard device. The basic mechanisms for the enhanced short-circuit current density are attributed to better light harvesting, increased scattering effects, and more efficient charge collection between the ITO and photoactive layers: Results show that-higher PCEs would be achieved by laser-pulse-treated electrodes.
Forming-free, bipolar resistivity switching characteristics of fully transparent resistive random access memory with IZO/alpha-IGZO/ITO structure
(2016-09-28)
Lo, Chun-Chieh
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Hsieh, Tsung-Eong
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材料科學與工程學系
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Department of Materials Science and Engineering
Fully transparent resistive random access memory (TRRAM) containing amorphous indium gallium zinc oxide as the resistance switching (RS) layer and transparent conducting oxides (indium zinc oxide and indium tin oxide) as the electrodes was prepared. Optical measurement indicated the transmittance of device exceeds 80% in visible-light wavelength range. TRRAM samples exhibited the forming-free feature and the best electrical performance (V-SET = 0.61 V; V-RESET = -0.76 V; R-HRS/R-LRS (i.e. the R-ratio) > 10(3)) was observed in the device subject to a post-annealing at 300 degrees C for 1 hr in atmospheric ambient. Such a sample also exhibited satisfactory endurance and retention properties at 85 degrees C as revealed by the reliability tests. Electrical measurement performed in vacuum ambient indicated that the RS mechanism correlates with the charge trapping/de-trapping process associated with oxygen defects in the RS layer.
Formation of Cu2O/Titanate/Titania Heterojunctions from Hydrothermally Induced Dual Phase Transitions
(2016-09-29)
Chaudhary, Manchal
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Chang, Sue-min
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Doong, Ruey-an
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Tsai, Hsin-mu
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環境工程研究所
A microwave-assisted hydrothermal method has been developed as an efficient approach to readily induce phase transition of titanate assemblies in conjunction with decoration of Cu2O dusters on the surface. The influence of Cu2+ ions on the hydrothermally induced structural evolution was examined, and the roles of heterojunctions in the resulting composites in charge separation for improved photocatalytic activity were clarified. Hierarchical titanate assemblies with high adsorption capacity for Cu2+-ions (95.7 meg) were prepared from a low alkaline condition, Microwave-assisted hydrothermal treatment was then used to transform the adsorbents into Cu2O/titanate/titania photocatalysts in 20 min via inducing titanate-to-titania and Cu2+-to-Cu2O dual transitions. While tubular architecture was maintained in, the composites, the Cu2O dusters highly dispersed on the surface. Adsorbed Cu2+ ions have been found to retard the titanate-to-titania transformation locally, thus leading to Cu2O/titanate/titania heterojanctions. The multiheterojunctions enabled the composites to exhibit 1.7-5.1 times higher activity than the commercial product P25 (k(obs), 0.06 min(-1)) for decomposition of bisphenol A due to charge separation. EPR results dearly reveal that the type II band alignment effectively drove electrons and holes to migrate toward the titania and the Cu2O moieties, respectively, and the titanate moiety positioning in between prevented back recombination. The optimal C(u)2O loading to the highest activity (k(obs),0.306 min(-1)) Was -3.7 wt %. Over the optimal amount, the rower reduction potential in the valence band of the Cu2O dusters compensated for the positive effect from charge separation, thus causing the activity to decline in turn.
Near-infrared sensitive organic-inorganic photorefractive device
(2016-10)
Marinova, Vera
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Liu, Ren-Chung
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Lin, Shiuan-Huei
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Chen, Ming-Syuan
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Lin, Yi-Hsin
Organic-inorganic hybrid structure, assembled by Rh-doped Bi12TiO20 crystal and liquid crystal (LC) layer, operating at near-infrared range is proposed and demonstrated. Due to the photorefractive properties of inorganic substrate, light illumination caused a space charge field which acts as a driving force for LC molecules re-alignment and subsequent refractive index modulation. All optically controlled phase retardation ability has been demonstrated supporting possibilities for further infrared applications.
Dark solitons in a spinor microcavity-polariton condensate
(2016-10)
Chen, Ting-Wei
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Jheng, Shih-Da
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Hsieh, Wen-Feng
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Cheng, Szu-Cheng
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物理研究所
Dark solitons of a two-component condensate occurring in nonresonantly-pumped microcavity polaritons (spinor MPCs) with integer vorticities, referred to as integer dark solitons (IDSs), can be excited by a laser beam with tunable polarization and power. We investigate the physical properties of stationary IDSs in a pure spinor MPCs without defects. From the excitations of a IDS, we show that the soliton is stable when the pump power is higher than a critical value. When the pump polarization is in favor of one component, we find that the critical pump power for the stabilization becomes higher. The stable IDS exists below a critical pump polarization. A stable phase diagram of IDSs in terms of the pump condition, i.e., pump polarization and power, is thus obtained. (C) 2016 Elsevier Ltd. All rights reserved.
Tamm plasmon selective thermal emitters
(2016-10-01)
Yang, Zih-ying
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Ishii, Satoshi
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Yokoyama, Takahiro
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Dao, Thang Duy
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Sun, Mao-guo
Selective thermal emissions from the excitation of Tamm plasmon polaritons (TPPs) are demonstrated. A TPP structure is composed of a distributed Bragg reflector (DBR) and a thin metal film on top. The tunability of the thermal emission was experimentally achieved only by changing the DBR\'s photonic bandgap. Low cost and large area selective thermal emitters can be realized by TPP-based structures. (C) 2016 Optical Society of America
Enhancing efficiency for additive-free blade-coated small-molecule solar cells by thermal annealing
(2016-10-01)
Tsai, Pei-Ting
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Meng, Hsin-Fei
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Chen, Yongsheng
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Kan, Bin
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Horng, Sheng-Fu
Blade coating was successfully applied to realise high-efficiency small-molecule organic solar cells (OSCs) with a solution-processed active layer comprising a small organic molecule DR3TBDTT with a benzo[1,2 -b: 4,5-b'] dithiophene (BDT) unit as the central building block as the donor and [6,6] -phenyl-C71 -butyric acid methyl ester (PC71BM) as the acceptor. Using chloroform as the solvent, a DR3TBDTT/PC71BM blend active layer without an additive was effectively formed through blade coating. The power conversion efficiency (PCE) of small organic molecule solar cells was enhanced by 3.7 times through thermal annealing at 100 degrees C. This method produces OSCs with a high PCE of up to 6.69%, with an open circuit voltage (V-oc) of 0.97 V, a short-circuit current density (J(sc)) of 12.60 mA/cm(2), and a fill factor (FF) of 0.55. (C) 2016 Elsevier B.V. All rights reserved.
Reading Subtitles and Taking Enotes While Learning Scientific Materials in a Multimedia Environment: Cognitive Load Perspectives on EFL
(2016-10)
Lin, John J. H.
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Lee, Yuan-Husan
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Wang, Dai-Yi
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Lin, Sunny S. J.
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教育研究所
The present study investigated the effects of providing subtitles and taking enotes on cognitive load and performance. A total of 73 English-as-a-Foreign-Language (EFL) undergraduates learned brain anatomy and cognitive functions through multimedia programs. We used a 2 (subtitle/no) x 2 (taking enotes/no) factorial design to test the following: (1) if cognitive demand would vary among different groups, and (2) if providing subtitles or taking enotes would facilitate learning. Four versions of multimedia materials had exactly the same content and differed only in the availability of subtitles or enote functions. The enote tool was designed for effective note-taking with regard to video/animation, making it possible to directly link notes to a specific scene. The results indicated that animation with subtitles groups help reduce cognitive load and increase performance. No significant differences were found in either cognitive load or post performance for those who learned with or without taking enotes. Although previous studies suggest subtitles may lead to a split-attention effect for native learners, we found a dual-coding effect (or reverse split-attention effect) for EFL learners.
Utilizing dual-pass composite-ring architecture for a stabilized and wavelength-selectable single-longitudinal-mode erbium-doped fiber laser
(2016-10)
Yeh, Chien-Hung
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Zhuang, Yuan-Hong
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Tsai, Ning
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Chen, Jing-Heng
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Chow, Chi-Wai
In this paper, we propose using a dual-pass composite-ring construction for a stable and wavelength-tunable erbium-doped fiber (EDF) laser with a single-longitudinal-mode (SLM) output. According to the proposed laser architecture, a flattened output power spectrum within a 0.57 dB power variation can be obtained in the tuning range of 1530 to 1560 nm. In addition, the measured optical signal-to-noise ratio (OSNR) of each output wavelength can be larger than 62.1 dB. Furthermore, a stable and tunable dual-wavelength output of the proposed EDF laser scheme can also be achieved in the same operation range by using two optical filters inside a ring cavity. Here, the maximum and minimum mode spacing of dual-wavelength lasing in the proposed EDF laser are 28.01 and 1.04 nm, respectively. In this measurement, the SLM performance and output stability of the proposed EDF laser are analyzed and discussed experimentally.
Using Structural Measures to Reduce Flood Losses in a Future Extreme Weather Event
(2016-10)
Wei, Hsiao-Ping
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Li, Hsin-Chi
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Yeh, Keh-Chia
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Liou, Jun-Jih
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Chen, Yung-Ming
Climate change is a real threat that brings heavier and more frequent extreme weather events. Many researchers have found that climate change will increase the risk of flooding around the world. The SOBEK inundation model and Taiwan Typhoon Loss Assessment System (TLAS) are used in this study to see if embankment and flood storage control measures can mitigate the impact (loss) of extreme events under climate change. Based on the simulation results, three inundation cases are simulated starting about 18 hr after the embankment is breached. When embankment and detention pond measures are not in place (Case A), the average flood depth in the catchment area caused by the TOP event is roughly 1.45 m. When adaptation measures such as [Case B raising embankments (Case B) and] are in place, the flood depth decreased by 39 and 33%, respectively. TLAS was used to evaluate the potential losses associated with the three cases (Case A, B, and C). When we add flood-control measures, the total loss reduced by adaptation measures for future extreme events in the Zhengwen River basin was NT$7 billion. This study provides applicable coping strategies for future extreme precipitation events that will effectively reduce the impact of extreme storm events.
Novel 1.5-2.4 GHz Tunable Single-to-Balanced Diplexer
(2016-10)
Chi, Pei-Ling
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Yang, Tao
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電機學院
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College of Electrical and Computer Engineering
A novel tunable single-to-balanced diplexer are proposed in this letter. The single-to-balanced diplexer consists of pairs of stepped-impedance resonators (SIRs), which are connected by back-to-back varactors in between. The diplexer can cover from 1.5 to 2.4 GHz, with constant absolute bandwidth. Moreover, the single-to-balanced diplexer exhibits differential outputs in each tuning state. Simulations and measurements are in excellent agreement. To the authors\' best knowledge, it is the first tunable single-to-balanced diplexer based on printed circuit board (PCB) technology that has been reported so far for multi-standard communication systems.
Three important amino acids control the regioselectivity of flavonoid glucosidation in glycosyltransferase-1 from Bacillus cereus
(2016-10)
Chiu, Hsi-Ho
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Hsieh, Yin-Cheng
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Chen, Ya-Huei
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Wang, Hsin-Ying
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Lu, Chia-Yu
Glycosyltransferase-1 from Bacillus cereus (BcGT1) catalyzes a reaction that transfers a glucosyl moiety to flavonoids, such as quercetin, kaempferol, and myricetin. The enzymatic glucosidation shows a broad substrate specificity when the reaction is catalyzed by wild-type BcGT1. Preliminary assays demonstrated that the F240A mutant significantly improves the regioselectivity of enzymatic glucosidation toward quercetin. To unveil and further to control the catalytic function of BcGT1, mutation of F240 to other amino acids, such as C, E, G, R, Y, W, and K, was performed. Among these mutants, F240A, F240G, F240R, and F240K greatly altered the regioselectivity. The quercetin-3-O-glucoside, instead of quercetin-7-O-glucoside as for the wild-type enzyme, was obtained as the major product. Among these mutants, F240R showed nearly 100 % product specificity but only retained 25 % catalytic efficiency of wild-type enzyme. From an inspection of the protein structure, we found two other amino acids, F132 and F138, together with F240, are likely to form a hydrophobic binding region, which is sufficiently spacious to accommodate substrates with varied aromatic moieties. Through the replacement of a phenylalanine by a tyrosine residue in the substrate-binding region, the mutants may be able to fix the orientation of flavonoids, presumably through the formation of a hydrogen bond between substrates and mutants. Multiple mutants-F240R_F132Y, F240R_F138Y, and F240R_F132Y_F138Y-were thus constructed for further investigation. The multiple points of mutants not only maintained the high product specificity but also significantly improved the catalytic efficiency, relative to F240R. The same product specificity was obtained when kaempferol and myricetin were used as a substrate.
Sensitivity to investor sentiment and stock performance of open market share repurchases
(2016-10)
Liang, Woan-lih
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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
This paper finds that stocks of repurchasers with high sensitivity to investor sentiment are more likely to be mispriced. Thus, such repurchases are followed by superior post-buyback stock performance. This abnormal return associated with sensitivity to sentiment cannot be explained by other undervaluation factors: book-to-market or prior return effects. My results are robust with factor model analysis and controls for contamination effects. I conclude that this sentiment-driven undervaluation may result from the difficulty to value and/or limits to arbitrage rather than investor overreaction. (C) 2016 Elsevier B.V. All rights reserved.
The detection of multiple illicit street drugs in liquid samples by direct analysis in real time (DART) coupled to Q-orbitrap tandem mass spectrometry
(2016-10)
Chen, Tai-Hung
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Hsu, Hsin-Yun
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Wu, Shu-Pao
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應用化學系
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Department of Applied Chemistry
Direct analysis in real time coupled to Q-orbitrap tandem mass spectrometry (DART-MS) without requiring preparatory procedures was used to directly detect trace amounts of illegal street drugs, namely p-chloroamphetamine, p-fluoromethamphetamine, gamma-hydroxybutyrate, ketamine, methamphetamine, 3,4-methylenedioxypyrovalerone, p-methylethcathinone, methylone, and nimetazepam, in solution and also in real drug samples. Exact mass determination of the drug samples was completed in less than 1 min. With the ability to rapidly identify drugs, this technique shows great potential as a useful analytical tool in the analysis of illicit street drugs, and has the significant advantages of simplicity and sensitivity without the sample preparation needed by other methods. (C) 2016 Elsevier Ireland Ltd. All rights reserved.
Temporal Control of Osteoblast Cell Growth and Behavior Dictated by Nanotopography and Shear Stress
(2016-10)
Dhawan, Udesh
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Pan, Hsu-An
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Chu, Ying Hao
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Huang, Guewha S.
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Chen, Po Chun
Biomaterial design involves assessment of cellular response to nanotopography parameters such as shape, dimension of nanotopography features. Here, the effect of nanotopography alongside the in vivo factor, shear stress, on osteoblast cell behavior, is reported. Tantalum oxide nanodots of 50 or 100 nm diameter were engineered using anodized aluminum oxide as a template. Bare tantalum nitride coated silicon substrates were taken as control (flat). MG63 (osteoblast) cells were seeded for 72 hours on flat, 50 or 100 nm nanodots and modulation in cell morphology, cell viability and expression of integrins was studied. Cells displayed a well-extended morphology on 50 nm nanodots in contrast to an elongated morphology on 100 nm nanodots, as observed by scanning electron microscopy and immunofluorescence staining, thereby confirming the cellular response to different nanotopographies. Based on quantitative real-time polymerase chain reaction data, a greater fold change in the expression of alpha 1, alpha 2, alpha 3, alpha 8, alpha 9, alpha V, beta 1, beta 4, beta 5, beta 7 and beta 8 integrins was observed in cells cultured on 100 nm than on 50 nm nanodots. Moreover, in the presence of a shear stress of 2 dyne/cm(2), a 52% increase in the cell viability after culturing the cells for 72 hours was observed on 100 nm nanodots as compared to 50 nm nanodots, thereby validating the effect of shear stress on cell behavior. Duration-of-culture experiments revealed 100 nm nanodots to be an ideal nanotopography choice to engineer optimized implant geometries for an ideal cell response. This study highlights the in vivo factors which need to be considered while designing nanotopographies for in vivo applications, for an ideal response as the cell-nanomaterial interface. Applications in the field of Biomedical, tissue engineering and cancer research are expected.
The natural history of type 1 spinal muscular atrophy in Taiwan
(2016-10-01)
Ou, S.
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Jong, Y.
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Ho, C.
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Lee, W.
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Lin, K.
Optimum synthesis of a 10-link gripping mechanism using new grasping indices
(2016-10)
Lin, Wen-Yi
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Hsiao, Kuo-Mo
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機械工程學系
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Department of Mechanical Engineering
When the traditional grasping index is used as an objective function, the optimized mechanism obtained offers good force transmission performance but unsound motion transmission for a 10-link gripping mechanism. Therefore, we first propose a new grasping index that is the product of the traditional grasping index and the effective force ratio. The effective force ratio reflects the motion transmission for the output links. The proposed grasping index is similar to the force transmission index discussed in the literature; however, different views of the physical meaning of the two components of the index and the necessity of the effective force ratio for optimum synthesis of the mechanism are presented. The second new grasping index proposed is the product of the first grasping index and the cosine value of the angle between the contact force and the contact velocity, originally used as a constraint. Using these new grasping indices, one can obtain sound optimum mechanism designs with a very small input force and contact velocity and with the maximum opening dimension equal to the object size. Furthermore, optimum synthesis for the gripping mechanism with an opening dimension larger than the object size is also investigated.
On Different-Dimensional Deployment Problems of Hybrid VANET-Sensor Networks with QoS Considerations (April, DOI 10.1007/s11036-016-0698-4, 2016)
(2016-10)
Lin, Chun-Cheng
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Chen, Peng-Chung
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Chang, Li-Wei
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工業工程與管理學系
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Department of Industrial Engineering and Management