Browsing by Issue Date, starting with "2018-07-25"

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Experimental investigation of the effect of compound protrusion-pin array on heat transfer in an internal rotating cooling channel
(2018-07-25)
Ullal, Ankith
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Hung, Shuo-Cheng
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Huang, Szu-Chi
;
Liu, Yao-Hsien
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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
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Jian, Cing-Yu
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Chen, Yi-Jia
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Lee, Si-Chen
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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
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Hsu, Wen-Hsuan
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Chou, Po-Han
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Yiin, Jia-Jean
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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.
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Jia, G.
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Gawlik, A.
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Kreusch, J.
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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
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Vinh, Nguyen Son
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Kumar, Ch. Pavan
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Chaurasia, Sumit
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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
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Tseng, Yu-Ting
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Lin, Wei-Ru
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Chen, Yen-Hsu
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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
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Chen, I-Chieh
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Chang, Ting-Chang
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Huang, J. C.
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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
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Lo, Yuan-Hsun
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Perry, K. E.
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Rodger, C. A.
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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
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Ramakrishnan, Resmi M.
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應用化學系
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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
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Chung, Kai-Min
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電信工程研究所
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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
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Van, Lan-Da
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Lin, Yu-Shu
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資訊工程學系
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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
Glycosaminoglycan-based hybrid hydrogel encapsulated with polyelectrolyte complex nanoparticles for endogenous stem cell regulation in central nervous system regeneration
(2018-08-01)
Jian, Wei-Hong
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Wang, Huan-Chih
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Kuan, Chen-Hsiang
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Chen, Ming-Hong
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Wu, Hsi-Chin
The poor regenerative capability of stem cell transplantation in the central nervous system limits their therapeutic efficacy in brain injuries. The sustained inflammatory response, lack of structural support, and trophic factors deficiency restrain the integration and long-term survival of stem cells. Instead of exogenous stem cell therapy, here we described the synthesis of nanohybrid hydrogel containing sulfated glycosaminoglycan-based polyelectrolyte complex nanoparticles (PCN) to mimic the brain extracellular matrix and control the delivery of stromal-derived factor-1 alpha (SDF-1 alpha) and basic fibroblast factor (bFGF) in response to matrix metalloproteinase (MMP) for recruiting endogenous neural stem cells (NSC) and regulating their cellular fate. Bioactive factors are delivered by electrostatic sequestration on PCN to amplify the signaling of SDF-1 alpha and bFGF to regulate NSC in vitro. In in vivo ischemic stroke model, the factors promoted neurological behavior recovery by enhancing neurogenesis and angiogenesis. These combined strategies may be applied for other tissue regenerations by regulating endogenous progenitors through the delivery of different kinds of glycosaminoglycan-binding molecules. (C) 2018 Elsevier Ltd. All rights reserved.
專號－馬來亞與印尼－群島的多元思想與疆界想像（續）：林清祥對馬來亞的願景：團結統一、非暴力、主權在民
(深河出版有限公司, 2018-08-01)
覃炳鑫
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劉璧嘉
10月22日現場討論
(深河出版有限公司, 2018-08-01)
陳冉涌
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郭佳
Secure and Fast Encryption (SAFE) with Classical Random Number Generators
(2018-08-01)
Deng, Lih-Yuan
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Shiau, Jyh-Jen Horng
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Lu, Henry Horng-Shing
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Bowman, Dale
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統計學研究所
Pseudo-random number generators (PRNGs) play an important role in both areas of computer simulation and computer security. Currently, there appears to be a huge divide between the types of PRNGs used in these two areas. For PRNGs in computer security applications, the security concern is extremely important. For PRNGs in computer simulation applications, the properties of high-dimensional equi-distribution, efficiency, long period-length, and portability are important. In recent years, there have been many PRNGs proposed in the area of computer simulation satisfying these nice properties. However, most of them are linear generators, thus sharing the same weakness in predictability. The major aim of this article is to propose a general class of secure generators, called SAFE (secure and fast encryption) generators, by properly "mixing" two baseline generators with the aforementioned properties to obtain a secure generator that would inherit these nice properties. Specifically, we propose applying a general mutual-shuffling method to certain linear generators, such as the currently most popular MT19937 generator and large-order multiple recursive generators, as well as outputting certain nonlinear transformations of the generated variates to construct secure PRNGS.
Integrated Portfolio Risk Measure: Estimation and Asymptotics of Multivariate Geometric Quantiles
(2018-08-01)
Sun, Edward W.
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Wang, Yu-Jen
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Yu, Min-Teh
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管理學院
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College of Management
Portfolio management and integrated risk management are more commonly applied toward enterprise risk management, requiring multivariate risk measures that capture the dependence among many risk factors. In this paper we propose the non-parametric estimator for multivariate value at risk (MVaR) and multivariate average value at risk (MAVaR) based on the multivariate geometric quantile approach and derive the symptotic properties of the proposed estimators for MVaR. We also present their performances under both simulated data and high-frequency financial data from the New York Stock Exchange. In addition, we compare our method with the delta normal approach and order statistics approach. The overall empirical results confirm that the multivariate geometric quantile approach significantly improves the risk management performance of MVaR and MAVaR.
Mixed yeast infections in Taiwan
(2018-08-01)
Yang, Yun-Liang
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Chu, Wen-Li
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Lin, Chih-Chao
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Zhou, Zi-Li
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Chen, Pei-Ning
Clinically significant yeast isolates were collected via Taiwan Surveillance of Antimicrobial Resistance of Yeasts (TSARY) in 2014, and mixed infections were investigated. Among 44 out of 1092 specimens containing multiple species, 17, 11, 5, 3, and 8 were from urine, sputum, blood, ascites, and 6 others, respectively. There predominant combinations of mixed infection were 14 Candida albicans/Candida glabrata, 13 C. albicans/Candida tropicalis, and 9 C. glabrata/C. tropicalis. Furthermore, we also detected fluconazole resistant isolates Candida norvegensis and Candida krusei. Hence, it is important to accurately identify the species with different drug susceptibilities when they are in the same specimen.
Surface Analysis and Optical Properties of Cu-Doped ZnO Thin Films Deposited by Radio Frequency Magnetron Sputtering
(2018-08-01)
Chen, Guo-Ju
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Jian, Sheng-Rui
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Juang, Jenh-Yih
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電子物理學系
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Department of Electrophysics
In this study, Cu-doped ZnO (CZO) thin films were grown on glass substrates by using the radio frequency magnetron sputtering technique. The effects of Cu doping on the structural, surface morphological, optical properties, and wettability behaviors of CZO thin films were investigated by X-ray diffraction (XRD), atomic force microscopy (AFM), UV-Visible spectroscopy, and contact angle measurement, respectively. The XRD results indicated that all CZO thin films were textured, having a preferential crystallographic orientation along the hexagonal wurtzite (002) axis. The average transmittance in the visible wavelength region was above 80% for all CZO thin films. The optical band gap of the CZO films decreased from 3.18 to 2.85 eV when the Cu-doping was increased from 2% to 10%. In addition, the water contact angle measurements were carried out to delineate the Cu-doping effects on the changes in the surface energy and wettability of the films.
影像選輯
(深河出版有限公司, 2018-08-01)
阿里．艾巴拉
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陳冉涌