Browsing by Issue Date, starting with "2014-03-12"

Now showing 1 - 20 of 27346

Effect of ion-milled barriers on electron transport in micrometer-sized tunnel junctions
(2014-03-12)
Lee, Yen-Chi
;
Lin, Yong-Han
;
Wu, Jong-Ching
;
Lin, Juhn-Jong
;
電子物理學系
We studied the electron transport properties of micrometre-sized all-Al tunnel junctions (TJs) between 2 and 300 K, in which the AlOx layer grown by O-2 plasma was moderately Ar-ion-milled prior to top electrode deposition. In contrast to the direct tunnelling in the TJs whose barriers are intact (not ion-milled), the zero-bias conductances and the current-voltage characteristics of the TJs as processed are found to be best described by the fluctuation-induced tunnelling conduction mechanism. This observation indicates the formation of nanoscopic incomplete pinholes in the AlOx layer, owing to large junction-barrier interfacial roughness introduced by the ion-milling process. Topographical features revealed by the cross-sectional transmission electron microscopy imaging of the TJ stack conform to this result. This study is of relevance to cases in which ion-milling techniques are applied in tailoring the TJ properties.
Anomalous anticrossing of neutral exciton states in GaAs/AlGaAs quantum dots
(2014-03-12)
Kumar, S.
;
Zallo, E.
;
Liao, Y. H.
;
Lin, P. Y.
;
Trotta, R.
We study the effects of heavy hole-light hole (HH-LH) mixing on fine-structure and polarization properties of neutral excitons ( X-0) confined in single GaAs/AlGaAs quantum dots (QDs) under the application of anisotropic biaxial stress. In the large HH-LH mixing regime, these properties are substantially different from the usually observed properties in the case of small or no mixing. By varying the applied stress, the mixing in the initially strain-free QDs changes from similar to 0 to similar to 70% and an anomalous anticrossing of the X-0 bright states is observed. The latter is attributed to stress-induced rotation of the in-plane principal axis of the QD confinement potential. We show that the analysis of free-excitonic emission of bulk GaAs surrounding the QDs not only allows estimation of the stress and mixing in the QDs, but also provides the quantum-confinement-induced HH-LH splitting of the as-grown QDs.
REAL-TIME PEOPLE COUNTING SYSTEM USING LAYER SCANNING METHOD
(2014-03-13)
Lin Daw-Tung
;
Jhuang Dong-Han
Disclosed herein is a method for counting the number of the targets using the layer scanning method. The steps of this method includes constructing a background frame, filtering the noise of foreground frame and classifying the targets, and screening the area of targets based on layer scanning to calculate the number of targets by determining the highest positions of the respective targets. In addition, the dynamic numbers of targets are calculated using algorithm. Accordingly, the present invention is beneficial in automatically, effectively and precisely calculating the number of the targets in/out a specific area, achieving the flow control for targets and reducing artificial error upon calculation.
Mechanics and response of a surface rock block subjected to pressure fluctuations: A plucking model and its application
(2014-03-13)
Pan, Yii-Wen
;
Li, Kuo-Wei
;
Liao, Jyh-Jong
;
土木工程學系
;
Department of Civil Engineering
Plucking (removal of rock blocks) is often the dominant mechanism for producing a scour hole on riverbeds comprised of heavily jointed rocic masses being subjected to pressure fluctuations from a jet flow. This paper explores the mechanics and response of a surface block subjected to pressure fluctuations. First a particle-flow simulation was conducted to demonstrate how repeated pressure fluctuations are able to gradually remove rock bridges in discontinuities surrounding a rock block, if a pressure fluctuation's intensity is substantial. As a consequence, these weak planes may become fully persistent. The block's uplift speed then depends on the pressure differences on the opposite (horizontal) faces, and the frictional resistance of the lateral discontinuities. This paper proposes a theoretical framework to model the mechanics and response of a rock block subjected to a sinusoidal pressure fluctuation. This model can be applied to estimate the development of a scour hole, through plucking, during a specific flood event. An example demonstrates the applicability of the proposed approach in predicting the potential depth of the scour hole. (C) 2013 Elsevier B.V. All rights reserved.
Increased Risk of Major Depression in the Three Years following a Femoral Neck Fracture-A National Population-Based Follow-Up Study
(2014-03-13)
Chang, Chih-Yu
;
Chen, Wen-Liang
;
Liou, Yi-Fan
;
Ke, Chih-Chi
;
Lee, Hua-Chin
Femoral neck fracture is common in the elderly, and its impact has increased in aging societies. Comorbidities, poor levels of activity and pain may contribute to the development of depression, but these factors have not been well addressed. This study aims to investigate the frequency and risk of major depression after a femoral neck fracture using a nationwide population-based study. The Taiwan Longitudinal Health Insurance Database was used in this study. A total of 4,547 patients who were hospitalized for femoral neck fracture within 2003 to 2007 were recruited as a study group; 13,641 matched non-fracture participants were enrolled as a comparison group. Each patient was prospectively followed for 3 years to monitor the occurrence of major depression. Cox proportional-hazards models were used to compute the risk of major depression between members of the study and comparison group after adjusting for residence and sociodemographic characteristics. The most common physical comorbidities that were present after the fracture were also analyzed. The incidences of major depression were 1.2% (n = 55) and 0.7% (n = 95) in the study and comparison groups, respectively. The stratified Cox proportional analysis showed a covariate-adjusted hazard ratio of major depression among patients with femoral neck fracture that was 1.82 times greater (95% CI, 1.30-2.53) than that of the comparison group. Most major depressive episodes (34.5%) presented within the first 200 days following the fracture. In conclusion, patients with a femoral neck fracture are at an increased risk of subsequent major depression. Most importantly, major depressive episodes mainly occurred within the first 200 days following the fracture.
Microstructural evolution and bonding mechanisms of the brazed Ti/ZrO2 joint using an Ag68.8Cu26.7Ti4.5 interlayer at 900 degrees C
(2014-03-14)
Wei, Shen-Hung
;
Lin, Chien-Cheng
;
材料科學與工程學系
;
Department of Materials Science and Engineering
In this study, 3 mol% Y2O3-stabilized zirconia (3Y-ZrO2) and commercially pure titanium (cp-Ti) joints were fabricated with an Ag68.8Cu26.7Ti4.5 interlayer (Ticusil) at 900 degrees C for various brazing periods. After brazing at 900 degrees C/0.1 h, Ti2Cu, TiCu, Ti3Cu4, and TiCu4 layers were present at the Ti/Ticusil interface, while TiCu and TiO layers were observed at the Ticusil/3Y-ZrO2 interface. In the residual interlayer, clumpy TiCu4 was formed along with the Ag solid phase. After brazing at 900 degrees C/1 h, Ti3Cu3O and Ti2O layers were formed at the interlayer/ZrO2 interface, while Cu2O was precipitated in the residual interlayer with [111](Cu2O)//[111](Ag) and (20 (2) over bar)(Cu2O)//(20 (2) over bar)(Ag). After brazing at 900 degrees C/6 h, a two-phase (alpha-Ti + Ti2Cu) region was observed on the Ti side with [2 (1) over bar(1) over bar0](alpha-Ti)//[100](Ti2Cu) and (0002)(alpha-Ti)//(0 (1) over bar3)(Ti2Cu), while the TiCu layer grew at the expense of Ti3Cu4 and TiCu4. The bonding mechanisms and diffusion paths were explored with the aid of Ag-Cu-Ti and Ti-Cu-O ternary phase diagrams.
Generation of multi-color carrier-envelope phase locked pulse with continuous color tunability
(2014-03-15)
Yabushita, Atsushi
;
Juang, Ding-Yi
;
Kao, Chih-Hsien
;
Baltuska, Andrius
;
Kobayashi, Takayoshi
Several methods exist to lock carrier envelope phase (CEP), which is generally not locked in common laser systems. Our previous work succeeded passive lock of CEP by using a technique of non-collinear optical parametric amplifier. In the present work, we have proposed and demonstrated two schemes to generate multi-color CEP-locked beams using the non-collinear optical parametric amplifier. In the first scheme, spatial filter in the spatially dispersed seed light was used to generate three-color CEP-locked pulse demonstrating ifs arbitral color tunability. In the second scheme, parabolic chirp was introduced on the seed pulse to generate two color CEP-locked pulses with continuous color tunability. (C) 2013 Elsevier B.V. All rights reserved.
Efficient high-power terahertz beating in a dual-wavelength synchronously mode-locked laser with dual gain media
(2014-03-15)
Huang, Y. J.
;
Tzeng, Y. S.
;
Tang, C. Y.
;
Chiang, S. Y.
;
Liang, H. C.
We originally present a novel tactic to accomplish a compact efficient dual-wavelength synchronously mode-locked laser by physically combining the Nd:YVO4 crystal to the Nd: GdVO4 crystal as a composite gain medium. With the developed method, the total output power at 1.06 mu m could be effectually produced to reach 1.3 W under the optimally balanced two-color intensities. The corresponding mode-locked pulse width and repetition rate are measured to be 47 ps and 2.86 GHz, respectively. Through the optical beating between two carrier frequencies of dual-color synchronous pulses, a train of 0.32 THz ultrashort pulses is further generated with the effective duration of down to 1.6 ps. (C) 2014 Optical Society of America
The Role of Psychosocial and Cultural Factors as Correlates of Depressive Symptoms in Chinese-American Older Adults
(2014-03-15)
Lin, Shumin
;
Liu, Jielin
;
Jang, Yuri
;
英語教學研究所
;
Institute of Teaching English to speakers of other Languages
Building upon the literature showing the negative impact of physical health constraints on depressive symptoms, this study examined the role of health and psychosocial and cultural factors as correlates of depressive symptoms in community-dwelling Chinese-American older adults. Data were drawn from surveys with 108 older Chinese Americans living in the Tampa and Orlando areas of Florida (M age = 70.6 years, SD=7.70). Results from hierarchical regression analysis suggest the importance of chronic health conditions and functional status as correlates of depressive symptoms. In addition, high levels of sense of mastery and acculturation were also found to be significant. Findings highlight the importance of psychosocial and cultural factors and suggest that such factors need to be considered in efforts to promote the mental health of ethnic minority older adults. Limitations and clinical implications of the findings are discussed.
Effective and site-specific phosphoramidation reaction for universally labeling nucleic acids
(2014-03-15)
Su, Yu-Chih
;
Chen, Hsing-Yin
;
Ko, Ni Chien
;
Hwang, Chi-Ching
;
Wu, Min Hui
Here we report efficient and selective postsynthesis labeling strategies, based on an advanced phosphoramidation reaction, for nucleic acids of either synthetic or enzyme-catalyzed origin. The reactions provided phosphorimidazolide intermediates of DNA or RNA which, whether reacted in one pot (one-step) or purified (two-step), were directly or indirectly phosphoramidated with label molecules. The acquired fluorophore-labeled nucleic acids, prepared from the phosphoramidation reactions, demonstrated labeling efficacy by their F/N ratio values (number of fluorophores per molecule of nucleic acid) of 0.02-1.2 which are comparable or better than conventional postsynthesis fluorescent labeling methods for DNA and RNA. Yet, PCR and UV melting studies of the one-step phosphoramidation-prepared FITC-labeled DNA indicated that the reaction might facilitate nonspecific hybridization in nucleic acids. Intrinsic hybridization specificity of nucleic acids was, however, conserved in the two-step phosphoramidation reaction. The reaction of site-specific labeling nucleic acids at the 5'-end was supported by fluorescence quenching and UV melting studies of fluorophore-labeled DNA. The two-step phosphoramidation-based, effective, and site-specific labeling method has the potential to expedite critical research including visualization, quantification, structural determination, localization, and distribution of nucleic acids in vivo and in vitro. (C) 2013 Elsevier Inc. All rights reserved.
Solid solution strengthening and phase transformation in high-temperature annealed Si80Ge20 alloy
(2014-03-15)
Chiang, Tun-Yuan
;
Wen, Hua-Chiang
;
Chou, Wu-Ching
;
Tsai, Chien-Huang
;
電子物理學系
This investigation demonstrates the temperature-dependent mechanical properties of Si80Ge20 alloy films via a nanoindenter in the indentation depth of 100 nm. The roughly equal root mean square roughness (R-rms) values and repeatable load-displacement (P-delta) curves for the samples ensure the mechanical performances mainly contributed from the influences of annealing temperatures. The hardness (H) values of samples increase with the temperatures of an initial annealing in the range from RT to 900 degrees C, and, conversely, decrease for annealing temperatures over 900 degrees C. Accordingly, both E/H and h(r)/h(max) values, exhibiting an inverse tendency in the above temperature range, hints that the solid solution strengthening effect and the softening phenomenon occur for the initial-annealing and over-annealing stages, respectively. In addition, grazing incidence X-ray diffraction (GIXRD) analysis demonstrates the lattice expansion and the broadened peak that attribute to the solid solution strengthening of samples and the segregation of Ge, respectively. Through observing the value of the (200) lattice spacing of 5.624 A for a 900 degrees C-annealed sample by transmission electron microscopy (TEM) analysis, it is verified that the segregation of Ge is responsible for the decreased hardness for the 1000 degrees C-annealed sample. (C) 2013 Elsevier B.V. All rights reserved.
Ultrahigh capacity 2 x 2 MIMO RoF system at 60 GHz employing single-sideband single-carrier modulation
(2014-03-15)
Lin, Chun-Ting
;
Ho, Chun-Hung
;
Huang, Hou-Tzu
;
Cheng, Yu-Hsuan
;
光電系統研究所
This article proposes and experimentally demonstrates a radio-over-fiber system employing single-sideband single-carrier (SSB-SC) modulation at 60 GHz. SSB-SC modulation has a lower peak-to-average-power ratio than orthogonal frequency division multiplex (OFDM) modulation; therefore, the SSB-SC signals provide superior nonlinear tolerance, compared to OFDM signals. Moreover, multiple-input multiple-output (MIMO) technology was used extensively to enhance spectral efficiency. A least-mean-square-based equalizer was implemented, including MIMO channel estimation, frequency response equalization, and I/Q imbalance compensation to recover the MIMO signals. Thus, using 2 x 2 MIMO technology and 64-QAM SSB-SC signals, we achieved the highest data rate of 84 Gbps with 12 bit/s/Hz spectral efficiency using the 7-GHz license-free band at 60 GHz. (C) 2014 Optical Society of America
Au nanoplates as robust, recyclable SERS substrates for ultrasensitive chemical sensing
(2014-03-15)
Lin, Wei-Hao
;
Lu, Yi-Hsuan
;
Hsu, Yung-Jung
;
材料科學與工程學系
;
Department of Materials Science and Engineering
With the structural advantages of being sharp and straight, Au nanoplates may work as a promising surface-enhanced Raman scattering (SERS) platform for detection of Raman-sensitive analytes. However, the utilization of Au nanoplates as realistic SERS substrates is still not widely investigated, especially in the practical detection of environmentally persistent pollutants. This work delivers the first successful demonstration of using Au nanoplate platform in practical SERS sensing toward a typical polycyclic aromatic hydrocarbons pollutant of pyrene. The samples were prepared using an environmentally benign seed-mediated growth approach without the post-purification treatment. It was found that Au nanoplates exhibited significantly enhanced SERS activities (enhancement factor = 7.30 x 10(7)) and achieved an extremely low detection limit (5 x 10(-10) M) toward pyrene molecules. Furthermore, the SERS activity of Au nanoplates can be fully recovered after repeatedly used and recycled in pyrene detection. These results manifest that the present Au nanoplates can serve as robust, recyclable SERS substrates that allow rapid detection of trace levels of analytes with a high degree of sensitivity and stability. The findings from this work may facilitate the use of Au nanoplate SERS substrates in more realistic applications such as biomolecule sensing and environmental monitoring. (C) 2013 Elsevier Inc. All rights reserved.
離家　一個人生活
(2014-03-16)
陳佩瑄
;
Department of Communication and Technology
;
傳播與科技學系
不知不覺中我已經過完我五分之一的人生。這二十一年有許多的愉快與不愉快，大部分的原因來自於我的家庭。
媽寶與寶媽　心靈無時差
(2014-03-16)
劉冠伶
;
Department of Communication and Technology
;
傳播與科技學系
我和媽媽，樂當媽寶與寶媽，現在還是像孩子一樣玩在一起，撒嬌可以繼續，但似乎是時候一起長大了。
動物安樂　多重差異
(2014-03-16)
蔡乙佳
;
Department of Communication and Technology
;
傳播與科技學系
長久以來，台灣政府都持續透過各種政策，加強流浪動物安置的待遇，並降低流浪動物的人道處理率。
靜態隨機存取記憶體
(2014-03-16)
莊景德
;
楊皓義
;
盧建宇
;
陳建亨
;
張琦昕
本發明揭露一種靜態隨機存取記憶體,其包含一預充裝置、一第一單元行陣列/周邊電路、及一第一漣波緩衝裝置。該預充裝置連接至一第一區域位元線,以對該第一區域位元線進行預充。該第一單元行陣列/周邊電路連接至該第一區域位元線,該第一單元行陣列/周邊電路具有多個單元以暫存資料,該多個單元連接至該第一區域位元線。該第一漣波緩衝裝置連接至該第一區域位元線及一第二區域位元線,該第一漣波緩衝裝置將該第一區域位元線的資料傳遞之該第二區域位元線。
就運動這檔事
(2014-03-16)
林庭宇
;
Department of Communication and Technology
;
傳播與科技學系
到現在的人生，也夠跟運動牽掛了，雖然沒有什麼偉大成就，但是運動這件事情或多或少也成為我生活的一部分。
高中籃球　淚水交織戰榮耀
(2014-03-16)
柯惠文
;
Department of Communication and Technology
;
傳播與科技學系
一○二學年度高中籃球聯賽順利落幕，在每個球員拼鬥背後，都有一個不為人知的故事。
從第一份工作學到的三堂課
(2014-03-16)
許仲廷
;
Department of Communication and Technology
;
傳播與科技學系
婚禮攝影是我的一份工作，也是很有趣的差事，讓我從中學到重要的三堂課。