Browsing by Issue Date, starting with "2019-09"

Now showing 1 - 20 of 6995

The Compress-and-Estimate Coding Scheme for Gaussian Sources
(2019-09-01)
Rini, Stefano
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Kipnis, Alon
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Song, Ruiyang
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Goldsmith, Andrea J.
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電子工程學系及電子研究所
We consider the multiterminal remote source coding problem of estimating a Gaussian signal from a hit-restricted representation of distributed linear measurements corrupted by additive white Gaussian noise. For this problem, we study the performance of the multiterminal compress-and-estimate (CE) coding scheme in which multiple remote encoders compress their measurements so as to minimize a local distortion measure which depends solely on the distribution of these measurements. In reconstruction, the decoder estimates the signal from the lossy-compressed measurements having full knowledge of the statistics of the source signal and the noisy measurements. The CE coding scheme is motivated by the scenario in which source encoders, due to their limited capabilities, operate according to a pre-determined compression strategy and cannot adapt to the sensing environment while the fusion center has full knowledge and computational capabilities. We focus, in particular, on two scenarios: the centralized observation model in which measurements are collected at a single remote encoder and the distributed observation model where measurements are provided to multiple remote sensors. In both scenarios, we investigate the performance attainable through the CE coding scheme in which the measurements are compressed according to a quadratic distortion measure and compare it to the performance of the coding scheme having full system knowledge.
Spectrogram for childhood asthma detection and analysis
(2019-09-01)
Kuo, Ho-Chang
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Lo, Chi-Chun
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Wang, Yan-Di
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Wu, Jheng-Dao
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Lin, Bor-Shyh
Effects of Object Category and Visual Representations on Recognition Accuracy
(2019-09-01)
Hsu, Chun-Cheng
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應用藝術研究所
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Institute of Applied Arts
Single Track of Selective Laser Melting Process: Modeling and Experimental Comparison
(2019-09-01)
Cheng, Chung-Wei
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Liou, Yao-Wen
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Lee, An-Chen
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Tsai, Mi-Ching
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機械工程學系
This study uses finite element software to simulate the single melted track of powder (Maraging Steel) on a substrate (S45C). The simulation model considers the absorption penetrating depth of laser power on the powder bed and the penetrating energy irradiating the substrate. A volumetric heat source is applied to the powder bed model, and a surface heat source is applied to the substrate model to obtain the simulated temperature field distribution. The interface melt width between the powder bed, substrate surface, and the substrate melt depth are estimated according to the temperature field distribution. In the experiments, a self-developed SLM experimental system is used, and the laser power and scanning speed are adjusted to observe the effect of a single continuous track on the S45C substrate, which is compared with a theoretical simulation.
Improving Reliability of High-Performance Ultraviolet Sensor in a-InGaZnO Thin-Film Transistors
(2019-09-01)
Tsai, Yu-Lin
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Chien, Yu-Chieh
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Chang, Ting-Chang
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Tsao, Yu-Ching
;
Tai, Mao-Chou
High-performance ultraviolet (UV) sensors using amorphous indium gallium zinc oxide thin-film transistors (a-IGZO TFTs) can detect I-ON/I-OFF ratio up to 10(6) and match the a-IGZO panel process. However, it has a reliability issue under long-term detection. When the top gate length of the dual gate TFT is small, it is twice as reliable as a TFT where the top gate fully covers the device. The electrical properties of the device correspond to the a-IGZO energy band, such that the top gate length was positively related to the underlying energy band diagram. The integrated systems engineering technology computer aided design (ISE-TCAD) electric field simulations show that the etch stop layer (ESL) electric field is weak in the small top gate device. This means that it is difficult for the holes to either be trapped in the ESL or to generate ionized oxygen vacancies.
Use of Aligned Microscale Sacrificial Fibers in Creating Biomimetic, Anisotropic Poly(glycerol sebacate) Scaffolds
(2019-09-01)
Li, Chen-Yu
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Hu, Ming-Hsien
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Hu, Jin-Jia
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機械工程學系
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Department of Mechanical Engineering
Poly(glycerol sebacate) (PGS) is a biocompatible, biodegradable elastomer that has been shown promise as a scaffolding material for tissue engineering; it is still challenging, however, to produce anisotropic scaffolds by using a thermoset polymer, such as PGS. Previously, we have used aligned sacrificial poly(vinyl alcohol) (PVA) fibers to help produce an anisotropic PGS membrane; a composite membrane, formed by embedding aligned PVA fibers in PGS prepolymer, was subjected to curing and subsequent PVA removal, resulting in aligned grooves and cylindrical pores on the surface of and within the membrane, respectively. PVA, however, appeared to react with PGS during its curing, altering the mechanical characteristics of PGS. In this study, aligned sacrificial fibers made of polylactide (PLA) were used instead. Specifically, PLA was blend-electrospun with polyethylene oxide to increase the sacrificial fiber diameter, which in turn increased the size of the grooves and cylindrical pores. The resultant PGS membrane was shown to be in vitro cyto-compatible and mechanically anisotropic. The membrane's Young's modulus was 1-2 MPa, similar to many soft tissues. In particular, the microscale grooves on the membrane surface were found to be capable of directing cell alignment. Finally, based on the same approach, we fabricated a biomimetic, anisotropic, PGS tubular scaffold. The compliance of the tubular scaffold was comparable to native arteries and in the range of 2% to 8% per 100 mmHg, depending on the orientations of the sacrificial fibers. The anisotropic PGS tubular scaffolds can potentially be used in vascular tissue engineering.
陽明之光－新任科技部政務次長謝達斌校友專訪
(國立陽明大學, 2019-09)
秘書室
Circulating MicroRNA Signature in Patients with Reversible Cerebral Vasoconstriction Syndrome
(2019-09-01)
Chen, Shih-Pin
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Chang, Yi-An
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Wang, Yen-Feng
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Fuh, Jong-Ling
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Chou, Chih-Hung
Contact Engineering High-Performance n-Type MoTe2 Transistors
(2019-09-01)
Mleczko, Michal J.
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Yu, Andrew C.
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Smyth, Christopher M.
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Chen, Victoria
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Shin, Yong Cheol
Semiconducting MoTe2 is one of the few two-dimensional (2D) materials with a moderate band gap, similar to silicon. However, this material remains underexplored for 2D electronics due to ambient instability and predominantly p-type Fermi level pinning at contacts. Here, we demonstrate unipolar n-type MoTe2 transistors with the highest performance to date, including high saturation current (>400 mu A/mu m at 80 K and >200 mu A/mu m at 300 K) and relatively low contact resistance (1.2 to 2 k Omega.mu m from 80 to 300 K), achieved with Ag contacts and AlOx encapsulation. We also investigate other contact metals (Sc, Ti, Cr, Au, Ni, Pt), extracting their Schottky barrier heights using an analytic subthreshold model. High-resolution X-ray photoelectron spectroscopy reveals that interfacial metal-Te compounds dominate the contact resistance. Among the metals studied, Sc has the lowest work function but is the most reactive, which we counter by inserting monolayer hexagonal boron nitride between MoTe2 and Sc. These metal-insulator-semiconductor (MIS) contacts partly depin the metal Fermi level and lead to the smallest Schottky barrier for electron injection. Overall, this work improves our understanding of n-type contacts to 2D materials, an important advance for low-power electronics.
Sustainable Desalination by 3:1 Reduced Graphene Oxide/Titanium Dioxide Nanotubes (rGO/TiONTs) Composite via Capacitive Deionization at Different Sodium Chloride Concentrations
(2019-09-01)
Lazarte, John Paolo L.
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Bautista-Patacsil, Liza
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Eusebio, Ramon Christian P.
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Orbecido, Aileen H.
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Doong, Ruey-an
The capability of novel 3:1 reduced graphene oxide/titanium dioxide nanotubes (rGO/TiONTs) composite to desalinate using capacitive deionization (CDI) employing highly concentrated NaCl solutions was tested in this study. Parameters such as material wettability, electrosorption capacity, charge efficiency, energy consumption, and charge-discharge retention were tested at different NaCl initial concentrations-100 ppm, 2000 ppm, 15,000 ppm, and 30,000 ppm. The rGO/TiONTs composite showed good material wettability before and after CDI runs with its contact angles equal to 52.11 degrees and 56.07 degrees, respectively. Its two-hour electrosorption capacity during CDI at 30,000 ppm NaCl influent increased 1.34-fold compared to 100 ppm initial NaCl influent with energy consumption constant at 1.11 kWh per kg with NaCl removed. However, the percentage discharge (concentration-independent) at zero-voltage ranged from 4.9-7.27% only after 30 min of desorption. Repeated charge/discharge at different amperes showed that the slowest charging rate of 0.1 Ag-1 had the highest charging time retention at 60% after 100 cycles. Increased concentration likewise increases charging time retention. With this consistent performance of a CDI system utilizing rGO/TiONTs composite, even at 30,000 ppm and 100 cycles, it can be a sustainable alternative desalination technology, especially if a low charging current with reverse voltage discharge is set for a longer operation.
Neural Activities Classification of Human Inhibitory Control Using Hierarchical Model
(2019-09-01)
Chikara, Rupesh Kumar
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Ko, Li-Wei
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交大名義發表
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生物科技學系
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生物資訊及系統生物研究所
Human inhibitory control refers to the suppression of behavioral response in real environments, such as when driving a car or riding a motorcycle, playing a game and operating a machine. The P300 wave is a neural marker of human inhibitory control, and it can be used to recognize the symptoms of attention deficit hyperactivity disorder (ADHD) in human. In addition, the P300 neural marker can be considered as a stop command in the brain-computer interface (BCI) technologies. Therefore, the present study of electroencephalography (EEG) recognizes the mindset of human inhibition by observing the brain dynamics, like P300 wave in the frontal lobe, supplementary motor area, and in the right temporoparietal junction of the brain, all of them have been associated with response inhibition. Our work developed a hierarchical classification model to identify the neural activities of human inhibition. To accomplish this goal phase-locking value (PLV) method was used to select coupled brain regions related to inhibition because this method has demonstrated the best performance of the classification system. The PLVs were used with pattern recognition algorithms to classify a successful-stop versus a failed-stop in left-and right-hand inhibitions. The results demonstrate that quadratic discriminant analysis (QDA) yielded an average classification accuracy of 94.44%. These findings implicate the neural activities of human inhibition can be utilized as a stop command in BCI technologies, as well as to identify the symptoms of ADHD patients in clinical research.
An Optically-Powered 432 MHz Wireless Tag for Batteryless Internet-of-Things Applications
(2019-09-01)
Cheng, Hao-Chung
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Chen, Yen-Ting
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Chen, Po-Hung
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Liao, Yu-Te
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電子工程學系及電子研究所
This paper presents an optically-powered wireless tag, integrating a charge pump (CP) and a low-power RF transmitter for batteryless Internet-of-Things (IoT) applications. The proposed charge pump with hysteresis regulation mechanism (HRM) powers the transmitter circuit using indoor light energy. The charge pump enables the transmitter whenever the output capacitor stores sufficient energy and guarantees a short period signal transmission. The proposed low-power transmitter contains the subharmonically injection-locked PLL and the capacitive coupling technique to achieve a large frequency multiplication ratio. The proposed batteryless wireless chip is fabricated in 0.18-mu m CMOS process. The measurement results demonstrate that the proposed charge pump provides a 1.1 to 1.3 V hysteresis regulated voltage under indoor light illumination larger than 300 lux. The charge pump achieves 84.1% peak efficiency and the communication distance of 3 meters is demonstrated while only consuming 248 mu W.
Modulation of the Visual to Auditory Human Inhibitory Brain Network: An EEG Dipole Source Localization Study
(2019-09-01)
Chikara, Rupesh Kumar
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Ko, Li-Wei
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交大名義發表
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生物科技學系
;
生物資訊及系統生物研究所
Auditory alarms are used to direct people's attention to critical events in complicated environments. The capacity for identifying the auditory alarms in order to take the right action in our daily life is critical. In this work, we investigate how auditory alarms affect the neural networks of human inhibition. We used a famous stop-signal or go/no-go task to measure the effect of visual stimuli and auditory alarms on the human brain. In this experiment, go-trials used visual stimulation, via a square or circle symbol, and stop trials used auditory stimulation, via an auditory alarm. Electroencephalography (EEG) signals from twelve subjects were acquired and analyzed using an advanced EEG dipole source localization method via independent component analysis (ICA) and EEG-coherence analysis. Behaviorally, the visual stimulus elicited a significantly higher accuracy rate (96.35%) than the auditory stimulus (57.07%) during inhibitory control. EEG theta and beta band power increases in the right middle frontal gyrus (rMFG) were associated with human inhibitory control. In addition, delta, theta, alpha, and beta band increases in the right cingulate gyrus (rCG) and delta band increases in both right superior temporal gyrus (rSTG) and left superior temporal gyrus (lSTG) were associated with the network changes induced by auditory alarms. We further observed that theta-alpha and beta bands between lSTG-rMFG and lSTG-rSTG pathways had higher connectivity magnitudes in the brain network when performing the visual tasks changed to receiving the auditory alarms. These findings could be useful for further understanding the human brain in realistic environments.
Next-Generation Sequencing Profiles of the Methylome and Transcriptome in Peripheral Blood Mononuclear Cells of Rheumatoid Arthritis
(2019-09-01)
Tseng, Chia-Chun
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Lin, Yuan-Zhao
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Lin, Chia-Hui
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Li, Ruei-Nian
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Yen, Chang-Yi
Using next-generation sequencing to decipher methylome and transcriptome and underlying molecular mechanisms contributing to rheumatoid arthritis (RA) for improving future therapies, we performed methyl-seq and RNA-seq on peripheral blood mononuclear cells (PBMCs) from RA subjects and normal donors. Principal component analysis and hierarchical clustering revealed distinct methylation signatures in RA with methylation aberrations noted across chromosomes. Methylation alterations varied with CpG features and genic characteristics. Typically, CpG islands and CpG shores were hypermethylated and displayed the greatest methylation variance. Promoters were hypermethylated and enhancers/gene bodies were hypomethylated, with methylation variance associated with expression variance. RA genetically associated genes preferentially displayed differential methylation and differential expression or interacted with differentially methylated and differentially expressed genes. These differentially methylated and differentially expressed genes were enriched with several signaling pathways and disease categories. 10 genes (CD86, RAB20, XAF1, FOLR3, LTBR, KCNH8, DOK7, PDGFA, PITPNM2, CELSR1) with concomitantly differential methylation in enhancers/promoters/gene bodies and differential expression in B cells were validated. This integrated analysis of methylome and transcriptome identified novel epigenetic signatures associated with RA and highlighted the interaction between genetics and epigenetics in RA. These findings help our understanding of the pathogenesis of RA and advance epigenetic studies in regards to the disease.
Average Entropy: Measurement of disorder for cardiac RR interval signals
(2019-09-01)
Hsu, Chang Francis
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Lin, Ping-Yen
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Chao, Hsuan-Hao
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Hsu, Long
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Chi, Sien
We introduce average entropy (AE) as a disorder measure of heart rate time series. The AE measurement reflects both the probability distribution of all discrete values in a time series and the randomness of the series. The AE analysis is able to differentiate the congestive heart failure (CHF), the healthy, and the atrial fibrillation (AF) subjects for both short and long heart rate time series. The differentiation accuracy of AE is higher than 90%. In addition, since the meaning of "disorder" is easily confused with "complexity", we explore the relation between them by analyzing heart rate time series. Specifically, we demonstrate that the complexity measured by entropy of entropy (EoE) versus the disorder measured by AE plot of heart rate time series exhibits a distinct inverted U relation. (C) 2019 Elsevier B.V. All rights reserved.
Infrared spectroscopy of the n-propyl and i-propyl radicals in solid para-hydrogen
(2019-09-01)
Pullen, Gregory T.
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Franke, Peter R.
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Haupa, Karolina A.
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Lee, Yuan-Pern
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Douberly, Gary E.
We report infrared spectra of the n- and i-propyl radicals isolated in solid para-hydrogen (p-H-2). Propyl radicals were produced via 248 nm irradiation of matrices formed by co-deposition of p-H-2 and either 1-iodopropane (forming n-propyl) or 2-iodopropane (forming i-propyl). Secondary photolysis was used to group spectral bands arising from the same species. In addition to those observed previously in either argon matrix or helium droplet spectra, we assign approximately 20 previously unreported bands. The assignment of features to propyl radicals is made via comparisons to VPT2+K anharmonic frequency computations. In separate measurements, propyl radicals were generated via the reaction between propene and hydrogen atoms produced within the p-H-2 matrix. Because the barriers are between 700 and 1500 cm(-1), the H + propene reaction is necessarily under tunneling control when carried out in solid p-H-2 at 3.3 K. i-Propyl radicals were produced in similar to 5-20 times greater abundance than n-propyl radicals, indicating that H atom addition to the terminal carbon is faster than addition to the central carbon. The Wentzl-Kramers-Brillouin approximation is applied to one-dimensional ab initio potentials to estimate the tunneling time constants for formation of n- and i-propyl. This model predicts the rate of addition to the terminal carbon (forming i-propyl) to be 17 times faster, in qualitative agreement with the experimental branching ratio. (C) 2019 Elsevier Inc. All rights reserved.
Depolarization Field in Ferroelectric Nonvolatile Memory Considering Minor Loop Operation
(2019-09-01)
You, Wei-Xiang
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Su, Pin
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電子工程學系及電子研究所
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Department of Electronics Engineering and Institute of Electronics
This letter investigates the depolarization field in a metal-ferroelectric-metal-insulator-metal (MFMIM) nonvolatile memory (NVM) considering the minor hysteresis loop operation. Our study indicates that, different from previous studies merely considering the major loop operation, the depolarization field for the ferroelectric undergoing the minor loop increases with decreasing oxide thickness. In other words, in addition to suppressing the gate leakage, thicker oxide thickness is favorable to lower the depolarization field and improves the retention for a given memory window (MW). This letter may provide insights for device design of ferroelectric nonvolatile memories.
Surface active flexible palladium nano-thin-film electrode development for biosensing
(2019-09-01)
Chang, Chia-Yu
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Huang, Yun-Tzu
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Chang, Pang-Chia
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Su, Chien-Hao
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Hsu, Kuo-Chen
Metal atoms on surface edges or with specific coordinates possess high surface potentials, and serve as core atoms for organic molecule bonding. However, these active metal atoms may lose their activity by self-diffusion on the surface. A polyethylene terephthalate (PET) substrate provided a stable rough surface in nanoscale for metal atoms absorption and formation of a stable and active nano-thin-film (NTF) surface. However, the NTF surface roughness decreased with increasing thickness of palladium (Pd) granules, indicating that the surface growth of the Pd film followed a Stranski-Krastanov-like growth model. Therefore, the proper thickness of Pd-NTF on PET substrate (Pd NTF-PET) was developed for electrochemical impedance spectroscopy (EIS). Protein was immobilized on the Pd NTF-PET electrodes within 15 min and its biosensing sensitivity was as low as 0.1 ng per-test in 1 mu l. We expect that the developed Pd NTF-PET electrode can be used for other biosensing applications as well.
Quantum encryption and generalized Shannon impossibility
(2019-09-01)
La, 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
The famous Shannon impossibility result says that any encryption scheme with perfect secrecy requires a secret key at least as long as the message. In this paper we provide its quantum analogue with imperfect secrecy and imperfect correctness. We also give a systematic study of information-theoretically secure quantum encryption with two secrecy definitions. We show that the weaker one implies the stronger but with a security loss in d, where d is the dimension of the encrypted quantum system. This is good enough if the target secrecy error is of o(d(-1)).
Volatile Resistive Switching Memory Based on Ag Ion Drift/Diffusion Part I: Numerical Modeling
(2019-09-01)
Wang, Wei
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Laudato, Mario
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Ambrosi, Elia
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Bricalli, Alessandro
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Covi, Erika
Resistive-switching random access memory (RRAM) devices based on filamentary switching are attracting widespread interest for their unique properties, such as high ON-OFF ratio, ultrasteep slope, good endurance, and low-current operation. Recently, volatile RRAMs based on Ag drift and diffusion were also demonstrated for possible applications such as crosspoint array selectors and neuromorphic computing. However, the mechanism of the volatile switching, namely, the spontaneous dissolution of the Ag filament, is still not clear. A deep understanding of the metallic filament formation and spontaneous disruption would strongly help the engineering of the device for optimized performances. Here, we present a numerical physics-based drift/diffusion modeling framework to describe the threshold switching, I-V characteristics, and morphological evolution of the metallic filament. The model can support TCAD-type device simulations for scaling, reliability, and variability studies.