Browsing by Issue Date, starting with "2018-07-20"

Now showing 1 - 20 of 10270

Thermally Stable High-Performance Polymer Solar Cells Enabled by Interfacial Engineering
(2018-07-20)
Chen, Chao-Hsuan
;
Lin, Zhi-Wei
;
Huang, Kuan-Min
;
Meng, Hsin-Fei
;
Chen, Szu-Han
Interfacial engineering plays an important role in determining the performance and stability of polymer solar cells (PSCs). In this study, thermally stable highly efficient PSCs are fabricated by incorporating a solution-processed cathode interfacial layer (CIL), including 4,4'-({[methyl(4-sulfonatobutyl)ammonio]bis(propane-3,1-diyl)}bis(dimethylammoniumdiyl))bis(butane-1-sulfonate) (MSAPBS) and polyethylenimine (PEI). For PSCs based on blends of poly{4,8-bis[5-(2-ethylhexyl)thiophen-2-yl]benzo[1,2-b;4,5-b]dithiophene-2,6-diyl-alt-[4-(2-ethylhexyl)-3-fluorothieno[3,4-b]thiophene-2-carboxylate-2,6-diyl]} (PBDTTT-EFT) and [6,6]-phenyl C-71-butyric acid methyl ester (PC71BM), the maximum power conversion efficiency (PCE) of inverted PSCs reaches 8.1% and 7.2% for MSAPBS and PEI CILs, respectively. The inverted PEI devices exhibit remarkable stability (lifetime >6000h) under accelerated thermal aging (at 80 degrees C in ambient environment), which is much superior to that of the device with commonly used LiF CIL (lifetime approximate to 33h). This stability represents the best result reported for PSCs. The promising results based on this strategy can stimulate further work on the development of novel CILs for PSCs and pave the way towards the realization of commercially viable PSCs with high performance and long-term stability.
交大e-News第259期-新一代農業設計師 AI農業應用─開創完善綜合性無毒科技務農系統
(2018-07-20)
國立交通大學秘書室
;
Secretariat
Exposure assessment of process by-product nanoparticles released during the preventive maintenance of semiconductor fabrication facilities
(2018-07-20)
Liao, Bo-Xi
;
Tseng, Neng-Chun
;
Li, Ziyi
;
Liu, Yingshu
;
Chen, Jen-Kun
This study characterized the process by product particles (mostly nanoparticles) released during the preventive maintenance of semiconductor fabrication facilities, such as chemical mechanical planarization (CMP), plasma-enhanced chemical vapor deposition (PECVD), and ion implantation. Manual sampling and real-time measurements with direct reading instruments were conducted to assess the exposure levels of nanoparticles and their physical and chemical properties. Significant amount of nanoparticles were observed in the breathing zone of the workers during the maintenance of the PECVD and ion implanters with the peak number concentrations as high as 6,470,000 and 65,444 #/cm(3), respectively, indicating that the deposited residual chemicals in the reaction chambers were released as airborne nanoparticles by the maintenance activities. In contrast, nanoparticles released during the maintenance of the local scrubber, CMP, and replacing CMP slurry drums were insignificant. Causes of the particle release were discussed and suggestions were made to mitigate the nanoparticle release and reduce the exposure levels.
Analysis of three-dimensional unsaturated-saturated flow induced by localized recharge in unconfined aquifers
(2018-07-20)
Chang, Chia-Hao
;
Huang, Ching-Sheng
;
Yeh, Hund-Der
;
環境工程研究所
;
Institute of Environmental Engineering
In the process of groundwater recharge, surface water usually enters an aquifer by passing an overlying unsaturated zone. Little attention has been given to the development of analytical solutions to a coupled unsaturated-saturated flow model due to localized recharge up to now. This paper develops a mathematical model to depict three-dimensional transient unsaturated-saturated flow in an unconfined aquifer with localized recharge on the ground surface. The model contains Richards' equation for unsaturated flow, a flow equation for saturated formation, and the Gardner constitutive model describing the behavior of unsaturated soil properties. Both flow equations are coupled through the continuity conditions of the head and flux at the water table. The semi-analytical solution to the coupled flow model is derived by the methods of Laplace transform and Fourier cosine transform. A sensitivity analysis is performed to explore the head response to the change in each of the aquifer parameters. A quantitative tool is presented to assess the recharge efficiency signifying the percentage of the water from the recharge to the aquifer. We found that the effect of unsaturated flow on the saturated hydraulic head is negligible if two criteria associated with the unsaturated soil properties and initial aquifer thickness are satisfied. The head distributions predicted from the present solution match well with those from finite-difference simulations. The predictions of the present solution also agree well with the observed data from a field experiment at an artificial recharge pond in Fresno County, California.
Effects of tuning the applied voltage pulse periods on the electroluminescence spectra of host-guest white light-emitting electrochemical cells
(2018-07-21)
Wu, Ming-Lun
;
Chen, Guan-Yu
;
Shih, Ting-An
;
Lu, Chin-Wei
;
Su, Hai-Ching
Solid-state white light-emitting electrochemical cells (LECs) are potential candidates in solid-state lighting due to their promising advantages of simple device structure, low-voltage operation and compatibility with inert cathode metals. Adjusting the correlated color temperature (CCT) of background illumination is highly desired for modern smart lighting systems. In this work, a novel technique to tune the CCT of electroluminescence (EL) from white LECs is proposed. Color tuning is based on adjusting the applied voltage pulse period on the host-guest white LECs and the working mechanism is illustrated. A shorter voltage pulse period is insufficient to completely charge the capacitive LEC device and thus the effective voltage applied on the device is lower. Since the host-guest energy level offsets favor carrier trapping, a lower effective applied voltage results in a more pronounced guest emission, rendering redder white EL with a lower CCT. On the other hand, a longer voltage pulse period facilitates more complete charging and the effective voltage applied on the white LEC is higher. A higher bias facilitates direct exciton formation on the host molecule and subsequent partial host-guest energy transfer generates bluer white EL with a higher CCT. By tuning the voltage pulse period from 0.2 to 20 ms, the CCT of EL resulting from white LECs ranges from 2482 to 5723 K. The CCT tuning range is sufficient for general lighting applications. In contrast to color tuning of white LECs under constant-voltage driving, in which >10 x brightness enhancement is accompanied by higher-CCT white EL, the discharging halfperiod in pulse-voltage driving provides relaxation time to turn off the device and reduces the average brightness of the white LECs driven under a longer voltage pulse period. Therefore, similar brightness can be achieved for white EL with different CCTs. No additional optical filtering device is needed for this novel color tuning technique and it has potential for use in solid-state lighting.
Communication: Mode-dependent excited-state lifetime of phenol under the S-1/S(2 )conical intersection
(2018-07-21)
Lai, Hsin Ying
;
Jhang, Wan Ru
;
Tseng, Chien-Ming
;
應用化學系
;
Department of Applied Chemistry
Phenol can serve as a model for examining the deactivation of the aromatic amino acid tyrosine following UV excitation, which mainly occurs through a repulsive pi sigma* state along the O-H bond. The reaction barrier formed by the conical intersection between the optically bright S-1 (pi pi*) state and the dissociative S-2 (pi sigma*) state does not inhibit O-H bond rupture even though the excitation energy is below the barrier height. To examine the O-H bond-rupture dynamics in association with the initial excited vibrational modes, we used a picosecond laser to investigate the vibrational-mode-dependent excited-state lifetime of phenol under the S-1/S-2 conical intersection. Unexpectedly short lifetimes were observed in the S-1 state for a '' symmetric vibrational modes (including nu(4), nu(16a), tau OH, and nu(5)). These results clarify recent theoretical calculations showing that the relaxation from S-1 to S-2 either occurs via symmetry-allowed non-adiabatic transitions or is topographically linked to a lower energy minimum on the multidimensional potential energy surface. Published by AIP Publishing.
Modeling the adoption of personal health record (PHR) among individual: the effect of health-care technology self-efficacy and gender concern
(2018-07-24)
Dutta, Bireswar
;
Peng, Mei-Hui
;
Sun, Shu-Lung
;
交大名義發表
;
National Chiao Tung University
Background: With the development of information technology (IT) and medical technology, medical information has been developed from traditional paper-based records into up-to-date medical information exchange system called personal health record (PHR). Empowering PHR provides health awareness and intention for health promotion. Objective: The purpose of this study was to present a research framework to examine individuals' intention to PHR use. Methods: This cross-sectional study used the questionnaire to collect data from the individual in Taiwan. Individual's intention to use PHR has been examined by a framework based on extended technology acceptance model (TAM), with gender and health-care technology self-efficacy (HTSE) as external variables. Additionally, gender differences were explored in perceptions and relationships among factors influencing an individual's intention to PHR use. The research framework was evaluated by structural equation modeling (SEM) and represented by Analysis of a Moment Structures (AMOS). Results: A total of 234 valid responses were used for analysis. The results suggest that the extended TAM model explains 40.6% of the variance of intention to PHR use (R-2 = 0.406). The findings also supported that perceived usefulness, perceived ease of use, and attitude toward using PHR significantly influenced individual's intention to PHR use. Additionally, results also indicated that women were more strongly influenced by perceptions of HTSE. Conclusions: The extended TAM model contributes reasonable explanation for interprets and anticipates of individuals' intention to use and adopt PHR. Moreover, the results have provided support for HTSE and gender as significant variables in TAM. However, the study identified three relevant factors directly and one factor indirectly influencing on individuals' intention to PHR use. Thus, health care providers and hospital authorities must take these factors and gender difference into consideration in the development and validation of the theories regarding the acceptance of PHR. Based on the findings, the theoretical and practical implications are discussed.
Characterization of domain distributions by second harmonic generation in ferroelectrics
(2018-07-24)
Zhang, Yuan
;
Zhang, Yi
;
Guo, Quan
;
Zhong, Xiangli
;
Chu, Yinghao
Domain orientations and their volume ratios in ferroelectrics are recognized as a compelling topic recently for domain switching dynamics and domain stability in devices application. Here, an optimized second harmonic generation method has been explored for ferroelectric domain characterization. Combing a unique theoretical model with azimuth-polarization-dependent second harmonic generation response, the complex domain components and their distributions can be rigidly determined in ferroelectric thin films. Using the proposed model, the domain structures of rhombohedral BiFeO3 films with 71 degrees and 109 degrees domain wall, and, tetragonal BiFeO3, Pb( Zr0.2Ti0.8)O-3, and BaTiO3 ferroelectric thin films are analyzed and the corresponding polarization variants are determined. This work could provide a powerful and all-optical method to track and evaluate the evolution of ferroelectric domains in the ferroelectric-based devices.
Experimental investigation of the effect of compound protrusion-pin array on heat transfer in an internal rotating cooling channel
(2018-07-25)
Ullal, Ankith
;
Hung, Shuo-Cheng
;
Huang, Szu-Chi
;
Liu, Yao-Hsien
;
機械工程學系
An experimental investigation was conducted to study the effect of protrusions and their combination with pins on heat transfer enhancement in a rotating internal passage with an orientation angle of 90 degrees for Reynolds numbers (Re) of 10,000 and 20,000. The trailing surface showed the highest Nusselt number (Nu). The highest and lowest local Nusselt number was at the front and back of the protrusion respectively. A short disturbed wake region was observed behind the protrusion as a result of complex three dimensional flow. Addition of pins in the configuration resulted in an increase of the average Nusselt number, specifically a 35%, 50% and 142% for trailing, static and leading surfaces respectively, compared to protrusions only case for Re of 10,000. On removal of the third column of protrusions, average Nusselt number showed a decrease of 8.25%, 3.1% and 2.3% for trailing, static and leading cases respectively, compared to the protrusion-pin case for Re of 10,000. It also caused elongation of the stagnation and wake flow fields around the fourth column comprising of pins. Pressure drop results indicated that the protrusion only case was the lowest compared to protrusion-pin.
Current Enhancement and Bipolar Current Modulation of Top-Gate Transistors Based on Monolayer MoS2 on Three-Layer WxMo1-xS2
(2018-07-25)
Chen, Kuan-Chao
;
Jian, Cing-Yu
;
Chen, Yi-Jia
;
Lee, Si-Chen
;
Chang, Shu-Wei
We demonstrated the top-gate transistors composed of monolayer MoS2 grown on three-layer alloys MoxW1-xS2 prepared by sequential sulfurization of predeposited transition metal films. The elemental mapping of the alloy indicates a uniform distribution of both cations Mo and W in the grown samples. Surprisingly, we find that the drain current of transistors could be enhanced by 2 orders of magnitude as the composition of Mo increases, whereas the gate-controlled current modulation turns bipolar and ultimately vanishes. These features might originate from the formation of in-gap defect states, with modest activation energy for transport and moderate hopping probability for current conduction, or a reduced electronic band gap of the conducting channel because of strain.
Estimating the survival of elderly patients diagnosed with dementia in Taiwan: A longitudinal study
(2018-07-25)
Lee, Kwo-Chen
;
Hsu, Wen-Hsuan
;
Chou, Po-Han
;
Yiin, Jia-Jean
;
Muo, Chih-Hsin
Background Dementia is characterized by prolonged progressive disability. Therefore, predicting mortality is difficult. An accurate prediction tool may be useful to ensure that end-of-life patients with dementia receive timely palliative care. Purpose This study aims to establish a survival prediction model for elderly patients with dementia in Taiwan. Methods Data from the 2001 to 2010 National Health Insurance Research Database in Taiwan were used to identify 37,289 patients with dementia aged >= 65 years for inclusion in this retrospective longitudinal study. Moreover, this study examined the mortality indicators for dementia among demographic characteristics, chronic physical comorbidities, and medical procedures. A Cox proportional hazards model with time-dependent covariates was used to estimate mortality risk, and risk score functions were formulated using a point system to establish a survival prediction model. The prediction model was then tested using the area under the receiver operating characteristic curve. Results Thirteen mortality risk factors were identified: age, sex, stroke, chronic renal failure, liver cirrhosis, cancer, pressure injury, and retrospectively retrieved factors occurring in the 6 months before death, including nasogastric tube placement, supplemental oxygen supply, >= 2 hospitalization, receiving >= 1 emergency services, >= 2 occurrences of cardiopulmonary resuscitation, and receiving >= 2 endotracheal intubations. The area under the receiver operating characteristic curves for this prediction model for mortality at 6 and 12 months were 0.726 and 0.733, respectively. Conclusions The survival prediction model demonstrated moderate accuracy for predicting mortality at 6 and 12 months before death in elderly patients with dementia. This tool may be valuable for helping health care providers and family caregivers to make end-of-life care decisions.
Fabrication of self-assembled spherical Gold Particles by pulsed UV Laser Treatment
(2018-07-26)
Schmidl, G.
;
Jia, G.
;
Gawlik, A.
;
Kreusch, J.
;
Schmidl, F.
We report on the fabrication of spherical Au spheres by pulsed laser treatment using a KrF excimer laser (248 nm, 25 ns) under ambient conditions as a fast and high throughput fabrication technique. The presented experiments were realized using initial Au layers of 100 nm thickness deposited on optically transparent and low cost Borofloat glass or single-crystalline SrTiO3 substrates, respectively. High (111)-orientation and smoothness (RMS approximate to 1 nm) are the properties of the deposited Au layers before laser treatment. After laser treatment, spheres with size distribution ranging from hundreds of nanometers up to several micrometers were produced. Single-particle scattering spectra with distinct plasmonic resonance peaks are presented to reveal the critical role of optimal irradiation parameters in the process of laser induced particle self-assembly. The variation of irradiation parameters like fluence and number of laser pulses influences the melting, dewetting and solidification process of the Au layers and thus the formation of extremely well shaped spherical particles. The gold layers on Borofloat glass and SrTiO3 are found to show a slightly different behavior under laser treatment. We also discuss the effect of substrates.
Pyrazine-incorporating panchromatic sensitizers for dye sensitized solar cells under one sun and dimlight
(2018-07-28)
Desta, Mulu Berhe
;
Vinh, Nguyen Son
;
Kumar, Ch. Pavan
;
Chaurasia, Sumit
;
Wu, Wei-Ti
New D-A--A type (D = electron donor, A = auxiliary acceptor, = -conjugated bridge, and A = electron acceptor/anchor) sensitizers with two bis(alkoxy)phenyl substituents incorporating thieno[3,4-b]pyrazines (TP) or a benzo[3,4-b]pyrazine (BP) entity as the auxiliary acceptor have been synthesized for application in dye-sensitized solar cells (DSSCs). Under 1 sun illumination, the DSSCs fabricated from the two BP dyes with a co-adsorbent have efficiencies of 8.39% and 9.03%, respectively. The latter surpasses that of the standard N719 dye (8.87%). Under dim light conditions MD7 exhibited a power conversion efficiency of 18.95% and 27.17% under 300 lux and 6000 lux irradiance, respectively.
AIDS-related opportunistic illnesses and early initiation of HIV care remain critical in the contemporary HAART era: a retrospective cohort study in Taiwan
(2018-07-28)
Lee, Chun-Yuan
;
Tseng, Yu-Ting
;
Lin, Wei-Ru
;
Chen, Yen-Hsu
;
Tsai, Jih-Jin
Background: No study has reported the epidemiology of AIDS-related opportunistic illnesses (AOIs) in patients with newly diagnosed HIV infection in Taiwan in the past decade. Understanding the current trends in AOI-related morbidity/mortality is essential in improving patient care and optimizing current public health strategies to further reduce AOIs in Taiwan in the era of contemporary highly active antiretroviral therapy (HAART). Methods: Eligible patients were evaluated at two referral centers between 2010 and 2015. The patients were stratified by date of diagnosis into three periods: 2010-2011, 2012-2013, and 2014-2015. The demographics, HIV stage at presentation according to the United States CDC 2014 case definition, laboratory variables, and the occurrence of AOIs and associated outcomes were compared among the patients. Logistic regression and Cox regression were respectively used to identify variables associated with the occurrence of AOIs within 90 days of HIV enrollment and all-cause mortality. Results: Over a mean observation period of 469 days, 1264 patients with newly diagnosed HIV with a mean age of 29 years and mean CD4 count of 275 cells/mu L experienced 394 AOI episodes in 290 events. At presentation, 37.7% of the patients had AIDS; the frequency did not significantly differ across groups. The overall proportion of AOIs within the study period was 21.0%, and no decline across groups was observed. The majority of AOls (91.7%) developed within 90 days of enrollment. All-cause and AOI-related mortality did not significantly differ across groups. Throughout the three study periods, AOIs remained the main cause of death (47/56, 83.9%), especially within 180 days of enrollment (40/42, 95.2%). A CD4 cell count of < 200 cells/mu L at presentation was associated with increased adjusted odds of an AOI within 90 days [adjusted odds ratio, 40.84; 95% confidence intervals (CI), 12. 59-132.49] and an elevated adjusted hazard of all-cause mortality (adjusted hazard ratio, 11.03; 95% CI, 1.51-80.64). Conclusions: Despite efforts toward HIV prevention and management, early HIV care in Taiwan continues to be critically affected by AOI-related morbidity and mortality in the era of contemporary HAART. Additional targeted interventions are required for the earlier diagnosis of patients with HIV.
Enhanced electrical behavior from the galvanic effect in Ag-Cu alloy electrode conductive bridging resistive switching memory
(2018-07-30)
Tseng, Yi-Ting
;
Chen, I-Chieh
;
Chang, Ting-Chang
;
Huang, J. C.
;
Shih, Chih-Cheng
In this study, an Ag-Cu alloy was chosen as the electrode in conductive bridging random access memory (CBRAM), with results indicating a significant decrease in forming voltage. In addition, resistive switching characteristics as well as a retention test indicated better stability and a resistive switching window of at least an order, The switching time of the Ag-Cu alloy CBRAM is shorter than that of both Ag and Cu electrode CBRAMs under fast current-voltage (fast I-V). The experimental result indicated that the mechanism was dominated by the galvanic effect. Active atoms (Ag) captured electrons of inactive atoms (Cu) and generated metallic ions (Cu ions) in the alloy electrode, Cu ions drifted into the insulator and generated a conductive path when applying voltage bias, The use of this alloy as an electrode in CBRAM can significantly decrease forming voltage and enhance CBRAM characteristics. Published by AIP Publishing.
On the number of rainbow spanning trees in edge-colored complete graphs
(2018-08-01)
Fu, Hung-Lin
;
Lo, Yuan-Hsun
;
Perry, K. E.
;
Rodger, C. A.
;
應用數學系
A spanning tree of a properly edge-colored complete graph, K, is rainbow provided that each of its edges receives a distinct color. In 1996, Brualdi and Hollingsworth conjectured that if K-2m is properly (2m 1)-edge-colored, then the edges of K-2m,, can be partitioned into m rainbow spanning trees except when m = 2. By means of an explicit, constructive approach, in this paper we construct [root 6m+9/3] mutually edge-disjoint rainbow spanning trees for any positive value of m. Not only are the rainbow trees produced, but also some structure of each rainbow spanning tree is determined in the process. This improves upon best constructive result to date in the literature which produces exactly three rainbow trees. (C) 2018 Elsevier B.V. All rights reserved.
Defect-Rich Brown TiO2-x Porous Flower Aggregates: Selective Photocatalytic Reversibility for Organic Dye Degradation
(2018-08-01)
Ullattil, Sanjay Gopal
;
Ramakrishnan, Resmi M.
;
應用化學系
;
Department of Applied Chemistry
A low-temperature, Mn(II)-assisted sol-solvothermal strategy has been developed for the synthesis of positively surface-charged defective brown TiO2-x flower aggregates with porous nature. The porous structure possessed enormous surface defect states such as trivalent titanium ion (TO3+) and oxygen vacancy (V-o) sites. The defect states present in the brown TiO2-x facilitated enhanced absorption even in the NIR region of the solar spectrum, whereas for the negatively surface-charged TiO2 sample, synthesized in the absence of Mn(II), the absorption was limited to the visible region. Obviously, band-gap narrowing occurred for brown TiO2-x as compared to the yellow TiO2 synthesized in the absence of Mn(II). Interestingly, studying the photocatalytic efficiency of these materials using a methyl orange-methylene blue (MO-MB) dye mixture model system under solar illumination revealed selective photocatalytic reversibility, with MB and MO photodegradation performed by yellow TiO2 and brown TiO2-x, respectively. This is the first report on the use of surface-charged brown TiO2-x with porous flower aggregate morphology for selective photocatalysis.
ON STATISTICALLY-SECURE QUANTUM HOMOMORPHIC ENCRYPTION
(2018-08-01)
Lai, Ching-Yi
;
Chung, Kai-Min
;
電信工程研究所
;
Institute of Communications Engineering
Homomorphic encryption is an encryption scheme that allows computations to be evaluated on encrypted inputs without knowledge of their raw messages. Recently Ouyang et al. constructed a quantum homomorphic encryption (QHE) scheme for Clifford circuits with statistical security (or information-theoretic security (IT-security)). It is desired to see whether an information-theoretically-secure (ITS) quantum FHE exists. If not, what other nontrivial class of quantum circuits can be homomorphically evaluated with IT-security? We provide a limitation for the first question that an ITS quantum FHE necessarily incurs exponential overhead. As for the second one, we propose a QHE scheme for the instantaneous quantum polynomial-time (IQP) circuits. Our QHE scheme for IQP circuits follows from the one-time pad.
Efficient Progressive Radiance Estimation Engine Architecture and Implementation for Progressive Photon Mapping
(2018-08-01)
Chiu, Ching-Chieh
;
Van, Lan-Da
;
Lin, Yu-Shu
;
資訊工程學系
;
Department of Computer Science
We propose a progressive radiance estimation engine (PREE) hardware architecture to accelerate the processing of the progressive photon mapping with satisfactory graphic quality. The presented PREE architecture consists of four progressive radiance estimation units (PREUs), approximate full task schedule-oriented hit-point update operation controller (AFTSO-HpUOC) and approximate data-independent schedule-oriented radiance evaluation controller (ADISO-REC). The PREUs accelerate the radiance estimation computation by a pipeline technique and share and configure the hardware resource for hit-point update operation and radiance evaluation. Through AFTSO-HpUOC and ADISO-REC, the data can be efficiently dispatched to achieve better parallelism and the data dependence can be alleviated within the four PREUs, respectively. The core area of the proposed PREE architecture implemented in TSMC 90-nm CMOS process is 1.78 mm(2). According to the post-layout simulation results, the implementation achieves 496.79 million hit-point update operations per second (MHpUO/s) and consumes 184 mW at 125 MHz for Cornell box with three balls.
詹澈訪談側記：從花園新城談起
(深河出版有限公司, 2018-08-01)
郭佳