Browsing by Issue Date, starting with "2016-02-17"

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USING DATA ENVELOPMENT ANALYSIS TO SUPPORT BEST-VALUE CONTRACTOR SELECTION
(2016-02-17)
Yang, Jyh-Bin
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Wang, Han-Hsiang
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Wang, Wei-Chih
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Ma, Shin-Min
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土木工程學系
Selecting an appropriate contractor or supplier is essential to the successful implementation of a public procurement project. The Taiwan government frequently applies the best-value (BV) tendering method, a multi-criteria evaluation method, to procure projects. However, the selection process of the winner for a BV-based procurement project is generally subjective and thus is easily accused of corruptions. To develop a systematic method to support contractor selection, this study proposes using the Data Envelopment Analysis (DEA) to facilitate the criteria evaluations for each bidder during the short-listing stage. The evaluation results of using the DEA are a list of potential BV winners who are then suggested to enter into the final selection stage. Based on three case studies related to service procurement projects, this research finds that the DEA is suitable of assessing the relative efficiencies among bidders when the BV approach is applied. Lessons learned here should be helpful in applying the DEA to aid bid evaluations in other supplier selection problems.
Development of Bifunctional Gadolinium-Labeled Superparamagnetic Nanoparticles (Gd-MnMEIO) for In Vivo MR Imaging of the Liver in an Animal Model
(2016-02-17)
Kuo, Yu-Ting
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Chen, Chiao-Yun
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Liu, Gin-Chung
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Wang, Yun-Ming
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生物科技學系
Liver tumors are common and imaging methods, particularly magnetic resonance imaging (MRI), play an important role in their non-invasive diagnosis. Previous studies have shown that detection of liver tumors can be improved by injection of two different MR contrast agents. Here, we developed a new contrast agent, Gd-manganese-doped magnetism-engineered iron oxide (Gd-MnMEIO), with enhancement effects on both T1-and T2-weighted MR images of the liver. A 3.0T clinical MR scanner equipped with transmit/receiver coil for mouse was used to obtain both T1-weighted spoiled gradient-echo and T2-weighted fast spin-echo axial images of the liver before and after intravenous contrast agent injection into Balb/c mice with and without tumors. After pre-contrast scanning, six mice per group were intravenously injected with 0.1 mmol/kg Gd-MnMEIO, or the control agents, i.e., Gd-DTPA or SPIO. The scanning time points for T1-weighted images were 0.5, 5, 10, 15, 20, 25, and 30 min after contrast administration. The post-enhanced T2-weighted images were then acquired immediately after T1-weighted acquisition. We found that T1-weighted images were positively enhanced by both Gd-DTPA and Gd-MnMEIO and negatively enhanced by SPIO. The enhancement by both Gd-DTPA and Gd-MnMEIO peaked at 0.5 min and gradually declined thereafter. Gd-MnMEIO (like Gd-DTPA) enhanced T1-weighted images and (like SPIO) T2-weighted images. Marked vascular enhancement was clearly visible on dynamic T1-weighted images with Gd-MnMEIO. In addition, the T2 signal was significantly decreased at 30 min after administration of Gd-MnMEIO. Whereas the effects of Gd-MnMEIO and SPIO on T2-weighted images were similar (p = 0.5824), those of Gd-MnMEIO and Gd-DTPA differed, with Gd-MnMEIO having a significant T2 contrast effect (p = 0.0086). Our study confirms the feasibility of synthesizing an MR contrast agent with both T1 and T2 shortening effects and using such an agent in vivo. This agent enables tumor detection and characterization in single liver MRI sections.
Mind-Wandering Tends to Occur under Low Perceptual Demands during Driving
(2016-02-17)
Lin, Chin-Teng
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Chuang, Chun-Hsiang
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Kerick, Scott
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Mullen, Tim
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Jung, Tzyy-Ping
Fluctuations in attention behind the wheel poses a significant risk for driver safety. During transient periods of inattention, drivers may shift their attention towards internally-directed thoughts or feelings at the expense of staying focused on the road. This study examined whether increasing task difficulty by manipulating involved sensory modalities as the driver detected the lane-departure in a simulated driving task would promote a shift of brain activity between different modes of processing, reflected by brain network dynamics on electroencephalographic sources. Results showed that depriving the driver of salient sensory information imposes a relatively more perceptually-demanding task, leading to a stronger activation in the task-positive network. When the vehicle motion feedback is available, the drivers may rely on vehicle motion to perceive the perturbations, which frees attentional capacity and tends to activate the default mode network. Such brain network dynamics could have major implications for understanding fluctuations in driver attention and designing advance driver assistance systems.
Stochastic growth dynamics and composite defects in quenched immiscible binary condensates
(2016-02-18)
Liu, I. -K.
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Pattinson, R. W.
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Billam, T. P.
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Gardiner, S. A.
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Cornish, S. L.
We study the sensitivity of coupled condensate formation dynamics on the history of initial stochastic domain formation in the context of instantaneously quenched elongated harmonically trapped immiscible two-component atomic Bose gases. The spontaneous generation of defects in the fastest condensing component, and subsequent coarse-graining dynamics, can lead to a deep oscillating microtrap into which the other component condenses, thereby establishing a long-lived composite defect in the form of a dark-bright solitary wave. We numerically map out diverse key aspects of these competing growth dynamics, focusing on the role of shot-to-shot fluctuations and global parameter changes (initial state choices, quench parameters, and condensate growth rates), with our findings also qualitatively confirmed by realistic finite-duration quenches. We conclude that phase-separated structures observable on experimental time scales are likely to be metastable states whose form is influenced by the stability and dynamics of the spontaneously emerging dark-bright solitary wave.
交大e-News第203期-交大前瞻火箭研究中心 APPL-9C雙節小火箭順利升空回收
(2016-02-19)
國立交通大學秘書室
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Secretariat
Duality in topological superconductors and topological ferromagnetic insulators in a honeycomb lattice
(2016-02-19)
Huang, Shin-Ming
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Tsai, Wei-Feng
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Chung, Chung-Hou
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Mou, Chung-Yu
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電子物理學系
The ground state of the large Hubbard U limit of a honeycomb lattice near half filling is known to be a singlet d + id-wave superconductor. It is also known that this d + id superconductor exhibits a chiral p + ip pairing locally at the Dirac cone, characterized by a 2Z topological invariant. By constructing a dual transformation, we demonstrate that this 2Z topological superconductor is equivalent to a collection of two topological ferromagnetic insulators. As a result of the duality, the topology of the electronic structures for a d + id superconductor is controllable via the change of the chemical potential by tuning the gate voltage. In particular, instead of always being a chiral superconductor, we find that the d + id superconductor undergoes a topological phase transition from a chiral superconductor to a quasihelical superconductor as the gap amplitude or the chemical potential decreases. The quasihelical superconducting phase is found to be characterized by a topological invariant in the pseudospin charge sector with vanishing both the Chern number and the spin Chern number. We further elucidate the topological phase transition by analyzing the relationship between the topological invariant and the rotation symmetry. Due to the angular momentum carried by the gap function and spin-orbit interactions, we show that by placing d + id superconductors in proximity to ferromagnets, varieties of chiral superconducting phases characterized by higher Chern numbers can be accessed, providing a platform for hosting large numbers of Majorana modes at edges.
Inhibition of breast cancer with transdermal tamoxifen-encapsulated lipoplex
(2016-02-19)
Lin, Yu-Ling
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Chen, Chia-Hung
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Wu, Hsin-Yi
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Tsai, Nu-Man
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Jian, Ting-Yan
Background: Tamoxifen is currently used for the treatment of both early and advanced estrogen receptor (ER) positive breast cancer in pre- and post-menopausal women. However, using tamoxifen routinely to inhibit endogenous or exogenous estrogen effects is occasionally difficult because of its potential side effects. Objectives: The aim of this study is to design a local drug delivery system to encapsulate tamoxifen for observing their efficacy of skin penetration, drug accumulation and cancer therapy. Methods: A cationic liposome-PEG-PEI complex (LPPC) was used as a carrier for the encapsulation of tamoxifen and forming 'LPPC/TAM' for transdermal release. The cytotoxicity of LPPC/TAM was analyzed by MTT. The skin penetration, tumor growth inhibition and organ damages were measured in xenograft mice following transdermal treatment. Results: LPPC/TAM had an average size less than 270 nm and a zeta-potential of approximately 40 mV. LPPC/TAM displayed dramatically increased the cytotoxic activity in all breast cancer cells, especially in ER-positive breast cancer cells. In vivo, LPPC drug delivery helped the fluorescent dye penetrating across the skim and accumulating rapidly in tumor area. Administration of LPPC/TAM by transdermal route inhibited about 86 % of tumor growth in mice bearing BT474 tumors. This local treatment of LPPC/TAM did not injury skin and any organs. Conclusion: LPPC-delivery system provided a better skin penetration and drug accumulation and therapeutic efficacy. Therefore, LPPC/TAM drug delivery maybe a useful transdermal tool of drugs utilization for breast cancer therapy.
Atomic and electronic aspects of the coloration mechanism of gasochromic Pt/Mo-modified V2O5 smart films: an in situ X-ray spectroscopic study
(2016-02-21)
Lu, Ying-Rui
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Hsu, Hsin-Hua
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Chen, Jeng-Lung
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Chang, Han-Wei
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Chen, Chi-Liang
In this work, gasochromic pristine and Mo-modified V2O5 thin films were prepared by the sol-gel spin coating method. Both films exhibit excellent gasochromic coloration. Synchrotron grazing incidence X-ray diffraction reveals that the Mo-modified V2O5 thin film is more amorphous than the pristine V2O5 thin film. X-ray absorption spectroscopy (XAS) was utilized to elucidate the modifications of the local electronic and atomic structures that are caused by Mo. In situ soft-XAS and in situ hard-XAS were performed to monitor the effect of the adsorption of dihydrogen on the charge state of vanadium and local atomic rearrangement in the gasochromic thin films. The gasochromic V2O5 film has a significantly pyramid-like oxygen-coordinated environment. However, the Mo-modified film exhibits mixed pyramid- and octahedral-like structures. Analytic results indicate that upon gasochromic coloration, adsorption of hydrogen adds electrons to the V 3d t(2g) orbital, lowering the charge state of vanadium. The films undergo structural modification before the valence is changed. The Mo-modified V2O5 film exhibits faster coloration because the apical V-O bond differs from that in the pristine V2O5 film. This in situ XAS allows real-time monitoring of changes in the element-specific local atomic structure during the gasochromic reaction and enables the elucidation of the gasochromic mechanism.
Theoretical and experimental studies for high-repetition-rate disordered crystal lasers with harmonic self-mode locking
(2016-02-22)
Sung, C. L.
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Lee, C. Y.
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Cho, H. H.
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Huang, Y. J.
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Chen, Y. F.
A harmonically self-mode-locked Nd:Sr3Y2(BO3)(4) disordered crystal laser with subpicosecond pulse duration is demonstrated. We exploit the damped harmonic oscillator model to numerically verify that the mode spacing of the laser cavity can be modified to be the harmonics of the free spectral range of the Fabry-Perot cavity when the optical length of the laser cavity is close to a commensurate ratio of the optical length of the FabryPerot cavity. In experiment, the Fabry-Perot cavity can be formed by the pump facet of the disordered crystal and the front mirror. A 110 GHz single-pulse harmonically mode-locked pulse train with pulse duration of 857 fs is experimentally achieved under optical lengths of 27.19 and 4.08 mm for the laser cavity and Fabry-Perot cavity respectively, corresponding to a fractional number of 20/3. A maximum output power of 162 mW is obtained at an incident pump power of 3.1 W. (C)2016 Optical Society of America
Low-Temperature and Ultrafast Synthesis of Patternable Few-Layer Transition Metal Dichacogenides with Controllable Stacking Alignment by a Microwave-Assisted Selenization Process
(2016-02-23)
Chen, Yu-Ze
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Medina, Henry
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Wang, Sheng-Wen
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Su, Teng-Yu
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Li, Jian-Guang
To date, the chemical vapor deposition (CVD) process is the most popular approach because of its high yield and quality. Nevertheless, the need for a high temperature and the relatively long process time within each cycle hinder the commercial development in terms of production cost. In this work, we demonstrate a fast (<3 min) and feasible approach to synthesizing a few-layers of WSe2 and MoSe2 on arbitrary substrates by a microwave-assisted selenization process. The transition metal dichalcogenides (TMDs) can be patterned by standard photolithography. Furthermore, controllable layered growth from horizontal to vertical alignment can be achieved, leading to an enhanced chemical catalytic activity caused by large edge sites (exposed areas). As a proof, a highly sensitive NO gas sensor based on vertical WSe2 was fabricated. Moreover, our microwave assisted selenization process can be further extended to achieve other two-dimensional TMD materials because of the simplicity of the process.
Atomic origin of the spin-polarization of the Co2FeAl Heusler compound
(2016-02-25)
Liang, Jaw-Yeu
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Lam, Tu-Ngoc
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Lin, Yan-Cheng
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Chang, Shu-Jui
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Lin, Hong-Ji
Using synchrotron x-ray techniques, we studied the Co2FeAl spin-polarization state that generates the half-metallicity of the compound during an A(2) (low-spin) -> B-2 (high-spin) phase transition. Given the advantage of element specificity of x-ray techniques, we could fingerprint the structural and magnetic cross-reactions between Co and Fe within a complex Co2FeAl structure deposited on a MgO (0 0 1) substrate. X-ray diffraction and extended x-ray absorption fine structure investigations determined that the Co atoms preferably populate the (1/4,1/4,1/4) and (3/4,3/4,3/4) sites during the development of the B-2 phase. X-ray magnetic spectroscopy showed that although the two magnetic elements were ferromagnetically coupled, they interacted in a competing manner via a charge-transfer effect, which enhanced Co spin polarization at the expense of Fe spin polarization during the phase transition. This means that the spin-polarization of Co2FeAl was electronically dominated by Fe in A(2) whereas the charge transfer turned the dominance to Co upon B-2 formation. Helicity-dependent x-ray absorption spectra also revealed that only the minority state of Co/Fe was involved in the charge-transfer effect whereas the majority state was independent of it. Despite an overall increase of Co2FeAl magnetization, the charge-transfer effect created an undesired trade-off during the Co-Fe exchange interactions, because of the presence of twice as many X sites (Co) as Y sites (Fe) in the Heusler X(2)YZ formula. This suggests that the spin-polarization of Co2FeAl is unfortunately regulated by compromising the enhanced X (Co) sites and the suppressed Y (Fe) sites, irrespective of the development of the previously known high-spin-polarization phase of B-2. This finding provides a possible cause for the limited half-metallicity of Co2FeAl discovered recently. Electronic tuning between the X and Y sites is necessary to further increase the spin-polarization, and likely the half-metallicity as well, of the compound.
Experimental violation of Bell inequalities for multi-dimensional systems
(2016-02-26)
Lo, Hsin-Pin
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Li, Che-Ming
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Yabushita, Atsushi
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Chen, Yueh-Nan
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Luo, Chih-Wei
Quantum correlations between spatially separated parts of a d-dimensional bipartite system (d >= 2) have no classical analog. Such correlations, also called entanglements, are not only conceptually important, but also have a profound impact on information science. In theory the violation of Bell inequalities based on local realistic theories for d-dimensional systems provides evidence of quantum nonlocality. Experimental verification is required to confirm whether a quantum system of extremely large dimension can possess this feature, however it has never been performed for large dimension. Here, we report that Bell inequalities are experimentally violated for bipartite quantum systems of dimensionality d=16 with the usual ensembles of polarization-entangled photon pairs. We also estimate that our entanglement source violates Bell inequalities for extremely high dimensionality of d>4000. The designed scenario offers a possible new method to investigate the entanglement of multipartite systems of large dimensionality and their application in quantum information processing.
Injectable insulin-lysozyme-loaded nanogels with enzymatically-controlled degradation and release for basal insulin treatment: In vitro characterization and in vivo observation
(2016-02-28)
Chou, Hao-Syun
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Larsson, Mikael
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Hsiao, Meng-Hsuan
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Chen, Yi-Chieh
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Roeding, Magnus
Diabetes is a common global disease that causes immense suffering for individuals and huge costs for the health care system. To minimize complications such as organ degeneration, diabetic patients are required to undergo treatments to maintain the blood glucose level in the normal range, ideally mimicking normal insulin secretion. The normal physiological insulin secretion pattern in healthy individuals consists of a base (basal) level through the day and increased secretion after meals (bolus insulin). Thus effective treatments may combine long acting, low-level insulin therapy with boosts of short acting insulin and/or oral agents. To achieve long term management of basal insulin level, an injectable insulin-loaded gel composed of self-assembled nanoparticles from carboxymethyl-hexanoyl chitosan (CHC) and integrated lysozyme for controlled biodegradation and insulin release was developed. In vitro characterizations and evaluations confirmed that lysozyme was active on CHC and that the amount of lysozyme in a CHC hydrogel determined the degradation and insulin release rate. The degradation products were found to be highly cytocompatible using a cell assay. In vivo evaluation of the system in a diabetic mouse model revealed that the fasted blood glucose level could be maintained in the normal range for 10 days with a single injection of insulin-loaded CHC-lysozyme gel. The insulin-loaded CHC-lysozyme gels clearly show promise for use as a novel injectable long-acting insulin delivery system, with potential to manage the basal insulin level for many days with a single injection. (C) 2015 Elsevier B.V. All rights reserved.
Iterative Symbol Decoding of Variable-Length Codes with Convolutional Codes
(2016-02-29)
Wu, Hung-Tsai
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Wu, Chun-Feng
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Chang, Wen-Whei
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傳播研究所
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Institute of Communication Studies
In this paper, we present a symbol-level iterative sourcechannel decoding (ISCD) algorithm for reliable transmission of variable-length codes (VLCs). Firstly, an improved source a posteriori probability (APP) decoding approach is proposed for packetized variable-length encoded Markov sources. Also proposed is a recursive implementation based on a three-dimensional joint trellis for symbol decoding of binary convolutional codes. APP channel decoding on this joint trellis is realized by modification of the Bahl-Cocke-Jelinek-Raviv algorithm and adaptation to the non-stationary VLC trellis. Simulation results indicate that the proposed ISCD scheme allows to exchange between its constituent decoders the symbol-level extrinsic information and achieves high robustness against channel noises.
A Rapid Fatigue Test Method on Micro Structures for High-Cycle Fatigue
(2016-03)
Shieh, Yi-Chueh
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Lin, Hsuan-Yu
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Hsu, Wensyang
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Lin, Yu-Hsin
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機械工程學系
Here, a rapid fatigue test method for micro structure is proposed, where the test sample is excited at its resonant frequency by an external actuator. Due to the scaling effect, a micro cantilever beam has high resonant frequency, so the testing time can be greatly reduced. In addition, no complicated built-in micro actuator is needed; therefore, it is easy to fabricate the test sample. Single-crystal silicon (SCS) beams are fabricated to demonstrate the proposed method here with two types of beams. A notch is designed near the fixed end to have stress concentration effect. The input voltage of the piezoelectric patch is adjusted to excite the cantilever beams at its resonant frequency to have different amplitudes to find the corresponding fatigue life, where a laser Doppler vibrometer is used to monitor displacements of the cantilever beam to control the stress amplitude. Then, the stress-life (S/N) curve of the silicon beam can be obtained. It is found that the fatigue limit of the SCS beam is about 1.33 GPa, and it takes only about 5.2 h to test 1.35 x 10(9) cycles at a resonant frequency of 72 kHz. Comparing with previous fatigue test methods with an external probe, testing 10(9) cycles at a frequency of 20 Hz will need 1.58 years, which indicates that the proposed rapid fatigue test method is particularly suitable for high-cycle fatigue test of micro structure.
六角柱體微型感測探針及其製法
(2016-03-01)
鄭裕庭
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陳益祥
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李元鼎
;
王覺瑋
本發明為一種六角柱體微型感測探針及其製法，係由一片金屬基電阻式溫度感測探針以及氧化銥/氯化銀酸鹼值感測探針覆合壓焊而成，可同時感測溫度及酸鹼值。此外，此微型感測探針之應力測試可達到3牛頓壓應力，可輕易地穿刺人體和動物的心肌或肌肉組織，故可應用於監測心肌狀態或感測肉類食品的新鮮度。
Suppressing Non-Uniform Tunneling in InAs/GaSb TFET With Dual-Metal Gate
(2016-03-01)
Hsu, Ching-Yi
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Chang, Chun-Yen
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Chang, Edward Yi
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Hu, Chenming
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材料科學與工程學系
Non-uniformity in electric field causes early onset of tunneling near the edge of InAs/GaSb hetero-junction tunneling field-effect transistors. When a small area, often an edge, of the tunneling junction has a lower turn-on voltage, the steep switching characteristic is degraded. Fermi pinning at InAs surface greatly worsen the uniformity. We propose a dual-metal gate structure to address the non-uniformity issue. With proper choice of work functions, the dual-metal gate structure can effectively suppress the early onset of edge tunneling and significantly improve the subthreshold swing.
Bipolar Conduction in Tin-Oxide Semiconductor Channel Treated by Oxygen Plasma for Low-Power Thin-Film Transistor Application
(2016-03)
Chen, Po-Chun
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Wu, Yung-Hsien
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Zheng, Zhi-Wei
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Chiu, Yu-Chien
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Cheng, Chun-Hu
In this paper, we investigated the bipolar conduction mechanism in thin-film transistors (TFTs) with oxygen plasma treatment on tin-oxide channel. The optimized p-type thin-oxide TFTs showed an on/off ratio of >10(4), a threshold voltage of -1.05 V, and a field-effect mobility of 2.14 cm(2).V-1.s(-1). By increasing the exposure time of oxygen plasma, excess oxygen was incorporated to thin-oxide channel and converted thin monoxide to oxygen-rich n-type thin dioxide, which in turn led to n-type operation. It indicated that oxygen plasma was the critical factor to determine oxygen concentration, oxygen vacancies, metal ions and channel polarity. This proposed oxygen-content tuning through plasma treatment approach shows great promise in simplification of TFT process that can achieve n-type and p-type TFTs under the same device process.
WIRELESS NEAR-INFRARED SPECTROSCOPE TO REAL-TIME QUANTITATIVELY ASSESS DORSAL FOOT PERIPHERAL CIRCULATION IN PATIENTS WITH DIABETES FOOT ULCER: A PILOT STUDY
(2016-03)
Lin, Yen Pin
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Chang, Chang Cheng
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Su, Zeng Wei
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Chang, Yin-Shuo
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Lin, Borshyh
Face-Based Heart Rate Signal Decomposition and Evaluation Using Multiple Linear Regression
(2016-03-01)
Lin, Kuan-Yi
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Chen, Duan-Yu
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Tsai, Wen-Jiin
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資訊工程學系
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Department of Computer Science
Contact measurements of the cardiac pulse using the conventional electrocardiogram equipment requires patients to wear adhesive gel patches or chest straps that can cause skin irritation and discomfort. Commercially available pulse oximetry sensors that attach to the fingertips or earlobes also cause inconvenience for patients and the spring-loaded clips can be painful to use. Therefore, a novel robust non-contact technique is developed for the evaluation of heart rate variation. According to the periodic variation of reflectance strength resulting from changes to hemoglobin absorptivity across the visible light spectrum as heartbeats cause changes to blood volume in the blood vessels in the face, a reflectance signal is decomposed from consecutive frames of the green channel of the facial region. Furthermore, ensemble empirical mode decomposition of the Hilbert-Huang transform (HHT) is used to acquire the primary heart rate signal while reducing the effect of ambient light changes. The effective instantaneous frequencies from intrinsic mode functions decomposed by HHT are implemented by the multiple-linear regression model to evaluate heart rates before the frequencies were rectified by maximum likelihood method assuming Poisson distribution, and the minimum elapse time for heart rate evaluation is also evaluated in the estimate process. Experimental results show that our proposed approach provides a convenient non-contact method to evaluate heart rate and outperforms the current state-of-the-art method with higher accuracy and smaller variance.