Browsing by Issue Date, starting with "2020-07-31"

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Ruthenium substituted pyrochlore metal oxide catalysts Y2Ce2-xRuxO7-delta (x=0-0.4) for oxidative steam reforming of ethanol
(2020-07-31)
Hsieh, Ho-Chen
;
Chen, Yun-Sheng
;
Weng, Sheng-Feng
;
Hsieh, Yu-Ping
;
Lee, Chi-Shen
Metal oxides Y2Ce2-xRuxO7-delta (x = 0-0.4) with partial substitution of Run+ cations in the host structure were synthesized to study their catalytic activity on oxidative steam reforming of ethanol (OSRE). The samples were characterized using X-ray diffraction (XRD), X-ray photoelectron spectra (XPS) and temperature-programmed reduction (TPR). The performances investigated by varied temperatures, Ru ion content, carbon-to-oxygen ratios and long-term stability. The lowest activation temperature on OSRE is 300 degrees C, which is significantly lower than that of La2Ce2-xRuxO7-delta (400 degrees C). The cell dimension of Y2Ce2-xRuxO7-delta was reduced compare to La2Ce2-xRuxO7-delta for the replacement of the Y3+ ion with La3+ ion. The reduced unit cell in the host structure not only increase the surface composition of the Ce4+ ions, but also induce the synergetic effect of Run+/Ru4+ (n > 4) and Ce4+/Ce3+, which lead to the enhanced OSRE activity. The optimized catalyst Y2Ce1.6Ru0.4O7-delta showed selectivity of hydrogen S-H2 = 84(4)% (Y-H2 = 2.5(1) mol/mol EtOH) and carbon monoxide S-CO = 48(1)% for long-term stability test at T = 300 degrees C, C/O = 0.5, and O-2/C2H5OH = 1.5. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.
Substrate-induced strain in 2D layered GaSe materials grown by molecular beam epitaxy
(2020-07-31)
Liu, Cheng-Wei
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Dai, Jin-Ji
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Wu, Ssu-Kuan
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Nhu-Quynh Diep
;
Sa-Hoang Huynh
Two-dimensional (2D) layered GaSe films were grown on GaAs (001), GaN/Sapphire, and Mica substrates by molecular beam epitaxy (MBE). The in situ reflective high-energy electron diffraction monitoring reveals randomly in-plane orientations of nucleated GaSe layers grown on hexagonal GaN/Sapphire and Mica substrates, whereas single-orientation GaSe domain is predominant in the GaSe/GaAs (001) sample. Strong red-shifts in the frequency of in-plane E2g2 vibration modes and bound exciton emissions observed from Raman scattering and photoluminescence spectra in all samples are attributed to the unintentionally biaxial in-plane tensile strains, induced by the dissimilarity of symmetrical surface structure between the 2D-GaSe layers and the substrates during the epitaxial growth. The results in this study provide an important understanding of the MBE-growth process of 2D-GaSe on 2D/3D hybrid-heterostructures and pave the way in strain engineering and optical manipulation of 2D layered GaSe materials for novel optoelectronic integrated technologies.
Ultrafast laser ablation of copper by GHz bursts
(2020-07-31)
Cheng, Chung-Wei
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Chen, Jinn-Kuen
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機械工程學系
;
Department of Mechanical Engineering
The ablation of copper, using a 10 GHz burst ultrafast laser with a wavelength of 1030 nm, a pulse duration of 1 ps, a variable total laser fluence, and a number of sub-pulses per burst, is investigated theoretically. A two-temperature model with an extended Lorentz-Drude model for dynamic optical properties is used to simulate the melting and ablation process. Due to the heat accumulation from the preceding pulses, multipulse laser ablation could be advantageous over a single pulse. Moreover, the ablation performance can be maximized by properly selecting the pulse number, separation time, and energy in a laser burst. The numerical result shows that the present prediction is in fairly agreement with existing experimental result. Under the same total laser fluence of 32 J/cm(2), a 10 GHz burst laser with an optimized 128 sub-pulse can significantly enhance the ablation depth, 4.2 times that a single pulse does. It is found that the optimized ablation depth is a linear function of the total fluence of ultrafast laser bursts.
Walking Strategies and Performance Evaluation for Human-Exoskeleton Systems under Admittance Control
(2020-08-01)
Liang, Chiawei
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Hsiao, Tesheng
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電機工程學系
;
Department of Electrical and Computer Engineering
Lower-limb exoskeletons as walking assistive devices have been intensively investigated in recent decades. In these studies, intention detection and performance evaluation are important topics. In our previous studies, we proposed a disturbance observer (DOB)-based torque estimation algorithm and an admittance control law to shape the admittance of the human-exoskeleton system (HES) and comply with the user's walking intention. These algorithms have been experimentally verified under the condition of no ground reaction force (GRF) in our previous studies. In this paper, we devised and integrated with the exoskeleton control system a sensing and communication module on each foot to measure and compensate for GRF. Rigorous theoretical analysis was performed and the sufficient conditions for the robust stability of the closed-loop system were derived. Then, we conducted level ground assistive walking repeatedly with different test subjects and exhaustive combinations of admittance parameters. In addition, we proposed two tractable and physically insightful performance indices callednormalized energy consumption index(NECI) andwalking distancein afixed period of timeto quantitatively evaluate the performance for different admittance parameters. We also compared the energy consumption for users walking with and without the exoskeleton. The results show that the proposed admittance control law reduces the energy consumption of the user during level ground walking.
Low Temperature Copper-Copper Bonding of Non-Planarized Copper Pillar With Passivation
(2020-08-01)
Tsai, Yi-Chieh
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Hu, Han-Wen
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Chen, Kuan-Neng
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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
Low-thermal-budget (180 degrees C for 15 sec) Cu pillar to Cu pillar bonding with Pd passivation under the atmosphere is developed without any planarization pretreatment before the bonding process. The bonded structure is investigated with material analysis, electrical measurement and reliability test. The results show that although the Cu pillar has a high roughness surface due to the electroplating process with a high deposition rate, Cu atoms can still diffuse and connect through the passivation layer and perform the low-thermal-budget Cu pillar direct bonding. Low specific contact resistance and stable resistance of daisy chain shown in the reliability test reveal the excellent bonding quality and integrity. This Cu-Cu bonding method is therefore favorable for chip stacking technology development in 3D packaging domain.
A review of bicycle-sharing service planning problems
(2020-08-01)
Shui, C. S.
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Szeto, W. Y.
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運輸與物流管理系註：原交通所+運管所
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Department of Transportation and Logistics Management
This paper reviews and systematically classifies the existing literature of bicycle-sharing service planning problems (BSPPs) at strategic, tactical, and operational decision levels with the reference to the novel bicycle sharing service planning process introduced herein. The current research gaps are identified and discussed. The future research directions of the three decision level problems are proposed according to four main categories, namely new diversity, realism, integrality, and technology. This review also points out important future research directions for multi-level BSPPs and the integration of bicycle sharing systems with existing multi-modal transportation systems.
Selective bypassing and mapping for heterogeneous applications on GPGPUs
(2020-08-01)
Emara, Moustafa
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Lai, Bo-Cheng
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交大名義發表
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National Chiao Tung University
Modern GPGPU supports executing multiple tasks with different run time characteristics and resource utilization. Having an efficient execution and resource management policy has been shown to be a critical performance factor when handling the concurrent execution of tasks with different run time behavior. Previous policies either assign equal resources to disparate tasks or allocate resources based on static or standalone behavior profiling. Treating tasks equally cannot efficiently utilize the system resources, while the standalone profiling ignores the correlated impact when running tasks concurrently and could hint incorrect task behavior. This paper addresses the above drawbacks and proposes a heterogeneity aware Selective Bypassing and Mapping (SBM) to manage both computing and cache resources for multiple tasks in a fine-grain manner. The light-weight run time profiling of SBM properly characterizes the disparate behavior of the concurrently executed multiple tasks, and selectively applies suited cache management and workgroup mapping policies to each task. When compared with the previous coarse-grained policies, SBM can achieve an average of 138% and up to 895% performance enhancement. When compared with the state-of-art fine-grained policy, SBM can achieve an average of 58% and up to 378% performance enhancement. (C) 2020 Elsevier Inc. All rights reserved.
MicroRNAs and Apoptosis in Colorectal Cancer
(2020-08-01)
Wang, Hsiuying
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統計學研究所
;
Institute of Statistics
Colorectal cancer (CRC) is the third leading cause of cancer death in the world, and its incidence is rising in developing countries. Treatment with 5-Fluorouracil (5-FU) is known to improve survival in CRC patients. Most anti-cancer therapies trigger apoptosis induction to eliminate malignant cells. However, de-regulated apoptotic signaling allows cancer cells to escape this signaling, leading to therapeutic resistance. Treatment resistance is a major challenge in the development of effective therapies. The microRNAs (miRNAs) play important roles in CRC treatment resistance and CRC progression and apoptosis. This review discusses the role of miRNAs in contributing to the promotion or inhibition of apoptosis in CRC and the role of miRNAs in modulating treatment resistance in CRC cells.
Geographic distance between co-inventors and firm performance: The moderating roles of interfirm and cross-country collaborations
(2020-08-01)
Moaniba, Igam M.
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Su, Hsin-Ning
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Lee, Pei-Chun
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科技管理研究所
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Institute of Management of Technology
Firms use strategic collaborations to reduce costs and increase productivity through shared technological capabilities, knowledge and resources. However, technological collaboration over geographic distance involves the risks of facing communication problems including vulnerability to the language difference, cultural issues, and political barriers. Consequently, firms engaging in technical collaborations across different locations often face higher communication (and other distance-related) costs, which in turn could affect their financial performance. This paper investigates the relationship between inventor distance and firm performance by employing panel fixed effect quantile regression techniques with interaction variables on a sample of 556 firms. The study finds empirical evidence that the geographic distance between collaborating inventors has a positive effect on firm performance. This effect is stronger in companies that engage in inventor collaborations across international borders and weaker in multi-national corporations that rely only on intra-firm inventor collaborations.
A Novel Means Combining Corona Discharge and Electrostatic Force-Induced Vibration for Convective Heat Transfer
(2020-08-01)
Tsui, Yeng-Yung
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Wei, Ting-Kai
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Wang, Chi-Chuan
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機械工程學系
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Department of Mechanical Engineering
A new design, not reported in the existing literature, combining features of ionic wind and mechanical vibration to induce appreciable airflow is developed. Its feasibility is demonstrated in a cooling system to enhance heat transfer. Ionic wind is generated using a thin, flexible plate as the emitting electrode and a heated, vertical plate as the collecting electrode. By placing a metal inductor close to the discharge electrode, an electrostatic field is formed. The electrode is attracted and thus moves toward the inductor owing to the electrostatic force created. To sustain periodic oscillation and produce large vibrational amplitudes, the inductor is grounded using current-limiting resistors. Vibrational characteristics are highly dependent on the corona voltage, resistance of the resistor, and position of the induction plate, which are examined in the experiments. It was found that the heat transfer enhancement is not improved at high corona voltages because the ionic wind overwhelms the mechanical effect of vibration. The vibrational effect becomes more prominent at low corona voltages with which the electrical field created by the corona discharge is not so intense. The maximum increase of heat transfer coefficient over that without vibration can be as large as 13.4% at the lowest corona voltage considered in the tests.
Characterization of Atmospheric PM(2.5)Inorganic Aerosols Using the Semi-Continuous PPWD-PILS-IC System and the ISORROPIA-II
(2020-08-01)
Le, Thi-Cuc
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Wang, Yun-Chin
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Pui, David Y. H.
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Tsai, Chuen-Jinn
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環境工程研究所
A semi-continuous monitoring system, a parallel plate wet denuder and particle into liquid sampler coupled with ion chromatography (PPWD-PILS-IC), was used to measure the hourly precursor gases and water-soluble inorganic ions in ambient particles smaller than 2.5 mu m in diameter (PM2.5) for investigating the thermodynamic equilibrium of aerosols using the ISORROPIA-II thermodynamic equilibrium model. The 24-h average PPWD-PILS-IC data showed very good agreement with the daily data of the manual 5 L/min porous-metal denuder sampler with R(2)ranging from 0.88 to 0.98 for inorganic ions (NH4+, Na+, K+, NO3-, SO42-, and Cl-) and 0.89 to 0.98 for precursor gases (NH3, HNO3, HONO, and SO2) and slopes ranging from 0.94 to 1.17 for ions and 0.87 to 0.95 for gases, respectively. In addition, the predicted ISORROPIA-II results were in good agreement with the hourly observed data of the PPWD-PILS-IC system for SO42-(R-2= 0.99 and slope = 1.0) and NH3(R-2= 0.97 and slope = 1.02). The correlation of the predicted results and observed data was further improved for NH(4)(+)and NO(3)(-)with the slope increasing from 0.90 to 0.96 and 0.95 to 1.09, respectively when the HNO(2)and NO(2)(-)were included in the total nitrate concentration (TN = [NO3-] + [HNO3] + [HONO] + [NO2-]). The predicted HNO(3)data were comparable to the sum of the observed [HNO3] and [HONO] indicating that HONO played an important role in the thermodynamic equilibrium of ambient PM(2.5)aerosols but has not been considered in the ISORROPIA-II thermodynamic equilibrium model.
【台灣民主運動支援會口述歷史系列（二）－暨戰後左翼口述計畫系列（十三）】編案
(深河出版有限公司, 2020-08-01)
人間思想編輯部
Morphological, Material, and Optical Properties of ZnO/ZnS/CNTs Nanocomposites on SiO(2)Substrate
(2020-08-01)
Tsai, Yu Sheng
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Lin, Xin Dai
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Chan, Wei Lun
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Tsai, Shang Che
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Liao, Wei Jen
Ultraviolet A light (UV-A, 320-400 nm), which is unblockable by sunscreen, requires careful detection for disease avoidance. In this study, we propose a novel photosensing device capable of detecting UV-A. Cancer-causing UV light can be simultaneously monitored with tiny rapid response sensors for a high carrier transition speed. In our research, a multifunctional ZnO/ZnS nanomaterial hybrid-sprinkled carbon nanotube (CNT) was created for the purpose of fabricating a multipurpose, semiconductorbased application. For our research, ZnO nanorods (NRs) were grown by using a facile hydrothermal method on SiO(2)substrate, then vulcanized to form ZnO/ZnS coreshell nanorods, which were sprinkled with carbon nanotubes (CNTs). Results indicate that SiO2/ZnO/ZnS/CNT structures exhibited a stronger conducting current with and without light than those samples without CNTs. Multiple material characterizations of the nanostructures, including of atomic force microscopy (AFM) surface morphology evaluation, scanning electron microscopy (SEM), and transmission electron microscopy (TEM) indicate that CNTs could be successfully spread on top of the ZnO/ZnS coreshell structures. Furthermore, chemical binding properties, material crystallinity, and optical properties were examined by X-ray diffraction (XRD), energy dispersive spectroscopy (EDS), and photoluminescence (PL). Owing to their compact size, simple fabrication, and low cost, ZnO/ZnS coreshell NRs/CNT/SiO2-based nanocomposites are promising for future industrial optoelectronic applications.
Anterior bone loss after cervical Bryan disc arthroplasty: insight into the biomechanics following total disc replacement
(2020-08-01)
Chen, Tse-Yu
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Chen, Wen-Hsien
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Tzeng, Chung-Yuh
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Huang, Chi-Wei
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Yang, Chih-Chang
BACKGROUND CONTEXT: Cervical disc arthroplasty (CDA) is an innovative procedure launched in the early 2000s. Compared with anterior cervical discectomy and fusion, many studies show that CDA offers equivalent clinical outcomes while reducing secondary procedures and total cost. PURPOSE: We sought to determine the incidence of anterior bone loss after CDA and the related biomechanical effects. STUDY DESIGN/SETTING: Retrospective chart review. PATIENT SAMPLE: Patients who underwent CDA with one level Bryan Disc (Medtronic SofamorDanek, Memphis, TN, USA) at one institution. OUTCOME MEASURES: Radiological measurements, including the extent of anterior bone loss, global alignment angle, shell angle, lordotic angle, mean degree of angle of the endplate with the horizontal line, global range of motion (ROM) and ROM of the index level were recorded. The grading of anterior bone loss of the index level was defined as Grade 0, no remodeling; Grade 1, spur disappearance or mild change in body contour; Grade 2, obvious bone regression with Bryan Disc exposure. METHODS: Anatomical measures and ROM were compared by grade of bone loss. RESULTS: Of the 121 patients included in the study, anterior bone loss was found in 53 (43.8%) on the upper adjacent level and 54 (44.6%) on the lower adjacent level. Twenty-nine patients (23.9%) had anterior bone loss in both levels. The majority of cases had Grade 1 anterior bone loss. Grade 2 bone loss was noted in the upper adjacent vertebra in only 5 patients and in 4 patients in the lower adjacent vertebra. Age, sex, operative level, and hybrid surgery had no effect on anterior bone loss. Most radiological assessments, including global alignment angle, lordotic angle, mean degree of angle of the endplate with the horizontal line, global ROM, and ROM of the index level, showed no correlation to anterior bone loss. Shell angle was found to be different in groups with or without remodeling in the upper adjacent level: 5.0 degreesin the Grade 0 group and 7.0 degrees in the Grade 1-2 group, p<. 05. CONCLUSIONS: Many more patients than predicted had anterior bone loss. Increasing the shell angle of the artificial disc may increase the incidence of anterior bone loss after CDA. Further study of the biomechanics following CDA should help clarify the mechanisms at work. (c) 2020 The Authors. Published by Elsevier Inc. This is an open access article under the CC BY-NC-ND license. (http://creativecommons.org/licenses/by-nc-nd/4.0/)
十月港九，草稿劇場
(深河出版有限公司, 2020-08-01)
趙川
Experimental study on bubble characteristics of time periodic subcooled flow boiling in annular ducts due to wall heat flux oscillation
(2020-08-01)
Chen, A.
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Lin, T. F.
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Ali, Hafiz Muhammad
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Yan, Wei-Mon
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機械工程學系
The significant effects of imposed wall heat flux oscillation on bubble characteristics of subcooled flow boiling with R-134a in horizontal annular ducts are experimentally performed in details. Specific emphasis has been applied on the bubble dynamics of the time periodic subcooled flow boiling characteristics influenced by the mean levels, amplitudes, and periods of the wall heat flux oscillations. The obtained experimental results have disclosed that the bubble parameters like the departure diameter, frequency and active nucleation site density, do oscillate periodically in time and are at the same frequency as the imposed wall heat flux oscillation. Nevertheless, these parameters also increase at long periods, high amplitudes of imposed heat flux oscillation or high values of mean imposed heat flux. Furthermore, the bubble size reduced after the time lag when the imposed heat flux decreases with time. (C) 2020 Elsevier Ltd. All rights reserved.
現實中的文學
(深河出版有限公司, 2020-08-01)
嚴靖
AntsOMG: A Framework Aiming to Automate Creativity and Intelligent Behavior with a Showcase on Cantus Firmus Composition and Style Development
(2020-08-01)
Chang, Chun-yien
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Chen, Ying-Ping
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人文社會學院
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資訊工程學系
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College of Humanities and Social Sciences
Creative behavior is one of the most fascinating areas in intelligence. The development of specific styles is the most characteristic feature of creative behavior. All important creators, such as Picasso and Beethoven, have their own distinctive styles that even non-professional art lovers can easily recognize. Hence, in the present work, attempting to achieve cantus firmus composition and style development as well as inspired by the behavior of natural ants and the mechanism of ant colony optimization (ACO), this paper firstly proposes a meta-framework, called ants on multiple graphs (AntsOMG), mainly for roughly modeling creation activities and then presents an implementation derived from AntsOMG for composing cantus firmi, one of the essential genres in music. Although the mechanism in ACO is adopted for simulating ant behavior, AntsOMG is not designed as an optimization framework. Implementations can be built upon AntsOMG in order to automate creation behavior and realize autonomous development on different subjects in various disciplines. In particular, an implementation for composing cantus firmi is shown in this paper as a demonstration. Ants walk on multiple graphs to form certain trails that are composed of the interaction among the graph topology, the cost on edges, and the concentration of pheromone. The resultant graphs with the distribution of pheromone can be interpreted as a representation of cantus firmus style developed autonomously. Our obtained results indicate that the proposal has an intriguing effect, because significantly different styles may be autonomously developed from an identical initial configuration in separate runs, and cantus firmi of a certain style can be created in batch simply by using the corresponding outcome. The contribution of this paper is twofold. First, the presented implementation is immediately applicable to the creation of cantus firmi and possibly other music genres with slight modifications. Second, AntsOMG, as a meta-framework, may be employed for other kinds of autonomous development with appropriate implementations.
A 2.17-mW Acoustic DSP Processor With CNN-FFT Accelerators for Intelligent Hearing Assistive Devices
(2020-08-01)
Lee, Yu-Chi
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Chi, Tai-Shih
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Yang, Chia-Hsiang
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電機工程學系
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Department of Electrical and Computer Engineering
This article presents an acoustic DSP processor containing a neural network core for intelligent hearing assistive devices. The processor includes the accelerators for convolutional neural networks (CNNs) and fast Fourier transform (FFT). The CNN-based speech enhancement algorithm predicts the desired mask for the Fourier spectrogram of the speech signal to enhance speech intelligibility. Several design techniques are applied to enable efficient hardware mapping. The computational complexity for the CNN can be reduced by 23.6% by frame sharing, and a fast mask generation + partial sums pre-computation technique further reduces output latency by up to 64%. The size of the memory for the model is reduced by 75% using weight quantization. FFT is implemented by leveraging the packing algorithm to reduce the computational complexity by 43%. Reconfigurable processing elements are shared to support both FFT and CNN, realizing a saving in the area of 42%. In addition, input sharing and output sharing are used to, respectively, reduce data movements by 94% and 75%. A reordered FFT structure also eliminates up to 256 multiplexers. Fabricated in a 40-nm CMOS technology, the chip's core area is 4.2 mm(2) and the power dissipation is 2.17 mW at a clock frequency of 5 MHz from a 0.6-V supply. The embedded CNN accelerator supports both convolutional and fully connected (FC) layers and achieves a comparable energy efficiency with state-of-the-art CNN accelerators, despite the flexibility for FFT. The speech intelligibility is enhanced by up to 41% in the low SNR regime.
Model-Based Synthetic Sampling for Imbalanced Data
(2020-08-01)
Liu, Chien-Liang
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Hsieh, Po-Yen
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工業工程與管理學系
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Department of Industrial Engineering and Management
Imbalanced data is characterized by the severe difference in observation frequency between classes and has received a lot of attention in data mining research. The prediction performances usually deteriorate as classifiers learn from imbalanced data, as most classifiers assume the class distribution is balanced or the costs for different types of classification errors are equal. Although several methods have been devised to deal with imbalance problems, it is still difficult to generalize those methods to achieve stable improvement in most cases. In this study, we propose a novel framework called model-based synthetic sampling (MBS) to cope with imbalance problems, in which we integrate modeling and sampling techniques to generate synthetic data. The key idea behind the proposed method is to use regression models to capture the relationship between features and to consider data diversity in the process of data generation. We conduct experiments on 13 datasets and compare the proposed method with 10 methods. The experimental results indicate that the proposed method is not only comparative but also stable. We also provide detailed investigations and visualizations of the proposed method to empirically demonstrate why it could generate good data samples.