Browsing by Issue Date, starting with "2009-08-30"

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Design and fabrication of a polyimide-based microelectrode array: Application in neural recording and repeatable electrolytic lesion in rat brain
(2009-08-30)
Chen, You-Yin
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Lai, Hsin-Yi
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Lin, Sheng-Huang
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Cho, Chien-Wen
;
Chao, Wen-Hung
The design and testing of a new microelectrode array, the NCTU (National Chiao Tung University) probe, was presented. Evaluation results showed it has good biocompatibility, high signal-to-noise ratio (SNR: the root mean square of background noise to the average peak-to-peak amplitude of spikes) during chronic neural recordings, and high reusability for electrolytic lesions. The probe was a flexible, polyimide-based microelectrode array with a long shaft (14.9 mm in length) and 16 electrodes (5 mu m-thick and 16 mu m in radius); its performance in chronic in vivo recordings was examined in rodents. To improve the precision of implantation, a metallic, impact-resistant layer was sandwiched between the polyimide layers to strengthen the probe. The three-dimensional (3D) structure of electrodes fabricated by electroplating produced rough textures that increased the effective surface area. The in vitro impedance of electrodes on the NCTU probe was 2.4 +/- 0.52 M Omega at 1 kHz. In addition, post-surgical neural recordings of implanted NCTU probes were conducted for up to 40 days in awake, normally behaving rats. The electrodes on the NCTU probe functioned well and had a high SNR (range: 4-5) with reliable in vivo impedance (<0.7 M Omega). The electrodes were also robust enough to functionally record events, even after the anodal current (30 mu A, 10 s) was repeatedly applied for 60 times. With good biocompatibility, high and stable SNR for chronic recording, and high tolerance for electrolytic lesion, the NCTU probe would serve as a useful device in future neuroscience research. (C) 2009 Elsevier B.V. All rights reserved.
Enhancement of electrochemical properties of screen-printed carbon electrodes by oxygen plasma treatment
(2009-08-30)
Wang, S. C.
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Chang, K. S.
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Yuan, C. J.
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生物科技學系
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Department of Biological Science and Technology
Plasma treatment is frequently used to clean and modify the surface of materials, including polymers and graphite. However, very limited information has been reported concerning the modification of a matrix. such as a screen-printed carbon electrode (SPCE) which is consisted of a mixture of graphite and pasting binder, using plasma. In this study. the surface characteristics and electrochemical properties of the plasma-treated SPCEs were investigated. The plasma-treated SPCEs performed a good electrochemical response (enhanced about 80-fold compared with those untreated electrode) and exhibited good reproducibility (CV of 4.8%). The response of plasma-treated electrodes was comparable with the electrodes modified with noble metal and superior to those electrode modified with carbon nanotube (CNT) (ca. 20-fold). SEM imaging revealed that an effective decomposition or removal of impurities and pasting binder on the surface of SPCEs during oxygen plasma treatment. The plasma treatment increases the step-like defects on the surfaces of graphite particles resulting in the generation of numerous edge planes. The phenomena could be responsible for the improvement of the electrochemical properties of SPCEs. The results also suggest that the plasma treatment condition is important. Over-erosion on the SPCE surface by high powered plasma may lead to the poor reproducibility of the SPCEs. (C) 2009 Elsevier Ltd. All rights reserved.
Single fluorescent gold nanoclusters
(2009-08-31)
Yuan, C. T.
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Chou, W. C.
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Tang, J.
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Lin, C. A.
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Chang, W. H.
Both ensemble and single-molecule measurements were performed to explore the fluorescence properties of Au nanoclusters (NCs). Photoinduced fluorescence enhancement was observed for ensemble NCs in solution, but photobleaching was found at ambient environments. At the single-molecule level, fluorescence blinking and single-step photobleaching were observed. Furthermore, their time-resolved fluorescence shows a single exponential decay with a lifetime of similar to 7 ns and is insensitive to changes in fluorescence intensity. The lifetime distribution is more homogeneous within ensemble Au NCs as compared to CdSe QDs. Therefore, Au NCs have potential applications as nontoxic fluorescent labels for lifetime-based imaging microscopy. However, their low quantum yields and poor photostability are disadvantageous factors, which require further improvement. (C) 2009 Optical Society of America
Arbitrary waveform synthesis by multiple harmonics generation and phasing in aperiodic optical superlattices
(2009-08-31)
Lin, Wei-Hsun
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Kung, A. H.
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光電工程學系
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Department of Photonics
The process of generating periodic optical waveforms includes the generation and phasing of several harmonics of a fundamental frequency. In this work, we show that simultaneous generation and phasing of the harmonics can be performed in a monolithic aperiodic optical superlattice (AOS). Stable periodic waveforms can thus be delivered to a predetermined location by simply sending a laser beam through a properly designed and fabricated AOS crystal. A detailed mathematical description for generating the domain pattern in such an AOS crystal is given and the process is numerically demonstrated. The waveform that is generated from a monolithic AOS is highly reproducible and phase stable. We also use propagation in air as an example to show how any predictable phase and amplitude modifications such as air dispersion that will alter the desired waveform can be pre-compensated in the design phase of the AOS crystal. (C) 2009 Optical Society of America
Transmit Equal Gain Precoding in Rayleigh Fading Channels
(2009-09-01)
Tsai, Shang-Ho
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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
Precoding with limited feedback information can achieve satisfactory performance while the amount of feedback information is kept small. In this paper, we analyze the theoretical performance of equal gain precoder and find that its performance is at most 1.049 dB worse than the optimal precoder no matter how the number of transmit antennas increases. Moreover, we analyze the performance degradation of the equal gain precoder due to scalar quantization theoretically. The result shows that 2-3 bits per transmit antenna (excluding the first antenna) can achieve 0.5-0.25-dB performance gap compared with the same scheme without quantization. Furthermore, we found that the equal gain precoder in general can achieve comparable performance with the Grassmannian precoder in the same moderate feedback bits. Simulation results are provided to corroborate the theoretical results.
Applying Particle Swarm Optimization to Parameter Estimation of the Nonlinear Muskingum Model
(2009-09-01)
Chu, Hone-Jay
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Chang, Liang-Cheng
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土木工程學系
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Department of Civil Engineering
The Muskingum model is the most widely used method for flood routing in hydrologic engineering. However, the application of the model still suffers from a lack of an efficient method for parameter estimation. Particle swarm optimization (PSO) is applied to the parameter estimation for the nonlinear Muskingum model. PSO does not need any initial guess of each parameter and thus avoids the subjective estimation usually found in traditional estimation methods and reduces the likelihood of finding a local optimum of the parameter values. Simulation results indicate that the proposed scheme can improve the accuracy of the Muskingum model for flood routing. A case study is presented to demonstrate that the proposed scheme is an alternative way to estimate the parameters of the Muskingum model.
Special Issue: Challenges for Advanced Technology Foreword
(2009-09-01)
Wen, Ue-Pyng
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Sheu, D. Daniel
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Hwang, Sheue-Ling
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Perng, Der-Baau
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工業工程與管理學系
製造長度較長且有複雜結構之布拉格光纖光柵以及用接續的方式來連接比相位光罩更長的光纖光柵的方法
(2009-09-01)
徐桂珠
;
賴杰
;
辛宸瑋
本案提出利用一種紫外光接續寫入與位置監控的技術來達到製作光纖光柵的方法,並利用相位光罩做為位置監控的元件。因為相位光罩的週期與紫外光寫入週期的相位誤差在5%以內,使紫外光寫入的精準度提升,光柵的頻譜響應也不至於劣化。並且由於相位光罩比起之前利用參考光纖光柵做為位置監控元件的專利有更好的繞射效率,容易作光學調準,而能達到更精準的監控技術。
OPTIMIZATION AND MODELING FOR MOS VARACTORS IN 65 nm LOW-POWER MIXED-SIGNAL/RADIO-FREQUENCY TECHNOLOGY
(2009-09-01)
Chen, Chia Chung
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Jiang, Meshon
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Chang, Li Ming
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Yeh, Tzu Jin
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Liu, Feng Ming
CMOS technology scaling opens tip the possibility of designing variable capacitors based oil a metal oxide semiconductor (MOS) structure with improved tuning range and quality factor. In this work, the high Q-factor 24 and 21, wide timing ratio 45% and 36% can be achieved by 65 nm low power technology n+/n-well and p+/p-well MOS varactor up to 10 GHZ, respectively. Meanwhile, the equivalent circuit model, to model intrinsic and extrinsic parameters of MOS varactor, also have demonstrated that parasitic resistance is a main issue to dominate Q-factors, and the measured flicker noise result of MOS varactor is directly dependant on gate leakage current. (C) 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 2119-2121. 2009; Published online in Wiley InterScience (www.intescience.wiley.com). DOI 10.1002/mop.24567
The effect of the geometry aspect ratio on the silicon ellipse-shaped surrounding-gate field-effect transistor and circuit
(2009-09-01)
Li, Yiming
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Hwang, Chih-Hong
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傳播研究所
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電子工程學系及電子研究所
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Institute of Communication Studies
The silicon (Si) surrounding-gate metal-oxide-semiconductor field-effect transistor (MOSFET) has ultimate gate structures and is a potential candidate for use in next-generation high-performance nano-devices. However, because of limitations of the fabrication process, theoretically ideally round shape of the surrounding gate may not always guarantee. These limitations may lead to the formation of an ellipse-shaped surrounding gate with major (a) and minor (b) axes of different lengths. In this study, the effect of the geometry aspect ratio, a/b, on the dc and ac characteristics of the 16 nm gate ellipse-shaped surrounding-gate MOSFETs and circuits is examined by using a three-dimensional coupled device-circuit simulation technique. The dependences of electrical characteristics on the geometry aspect ratio are evaluated with reference to various device characteristics and the circuit properties, including the circuit gain, the 3 dB bandwidth, the unity-gain bandwidth, the rise/fall time and the delay time. In analog circuits, the device with an aspect ratio of less than 1 is promising because the short-channel effect is suppressed. However, for a digital circuit configuration, the transient response of the circuit relies on the charge/discharge capability of the transistor. Thus, a device with a large aspect ratio, such as 2, will be more suitable for digital applications.
The origin of Al(OH)(3)-rich and Al(13)-aggregate flocs composition in PACl coagulation
(2009-09-01)
Lin, Jr-Lin
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Huang, Chihpin
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Chin, Ching-Ju M.
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Pan, Jill R.
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環境工程研究所
The composition of hydrolyzed Al species is essential for the understanding of coagulation with Al-based coagulants. Surface characteristics of flocs formed by coagulation with two distinct polyaluminum chloride (PACl) coagulants were identified. One commercial coagulant (PACl-C) with voluminous monomeric Al and colloidal Al(OH)(3) and a custom-made PACl (PACl-Al(13)) containing high Al(13) content were applied to destabilize kaolin particles. The flocs formed by PACl-C and PACl-Al(13) at neutral and alkaline pH ranges, respectively, were observed by FE-SEM and HR-TEM. In addition, the Al composition of these flocs was characterized by XPS and HR-XRD, and the imaging of Al(OH)(3) precipitates and Al(13) aggregates were conducted by SEM as well as tapping mode AFM in liquid system. The observations of flocs indicate that the morphology of Al(OH)(3)-rich flocs are fluffy and porous around the edge of flocs, while the Al(13)-aggregate flocs have a glossy contour and irregular structure. Both Al(OH)(3)-rich and Al(13)-aggregate flocs do not possess well-formed crystalline structure except for the Al(13)-like crystal exists in the Al(13)-aggregate flocs. Among Al(OH)(3) precipitates, colloidal Al(OH)(3) is micro-scale in size, while amorphous Al(OH)(3) is nano-scale. During the formation of Al(13) aggregates, some coiled and clustered Al(13) aggregates with smoother surface were observed. The XPS study on floc surface showed that tetrahedral (Al(IV))/octahedral (Al(VI)) Al ratio on the surfaces of PACl-C and PACl-Al(13) flocs is 1:1.6 and 1:9.9, respectively. Of the in situ formed Al(13), almost half of Al-hydroxide precipitates on the surface of Al(OH)(3)-rich flocs possess the Al(IV) center. It also found that the irregularly aggregated Al(13) with a similar Al(13) Crystalline structure subsists on the surface of Al(13)-aggregate flocs. (C) 2009 Elsevier Ltd. All rights reserved.
Assembly of Micro-3-D Components on SOI Wafers Using Novel SU-8 Locking Mechanisms and Vertical One-Push Operation
(2009-09-01)
Chiu, Yi
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Wu, Chang-Shiou
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Huang, Wei-Zhi
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Wu, Jhong-Wei
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電控工程研究所
A novel out-of-plane assembly technique of 3-D microstructures is proposed and demonstrated by using simple vertical one-push operations. This one-push method has large probe positioning tolerance in both vertical and lateral directions to reduce the overall complexity of the assembly process. Micromirrors and corner cube reflectors are fabricated on silicon-on-insulator wafers using SU-8 photoresist as a second structure layer in a low-temperature process. Batch assembly of multiple mirrors assembled simultaneously is demonstrated.
Mutually orthogonal hamiltonian connected graphs
(2009-09-01)
Ho, Tung-Yang
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Lin, Cheng-Kuan
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Tan, Jimmy J. M.
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Hsu, Lih-Hsing
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資訊工程學系
in this work, we concentrate on those n-vertex graphs G with n >= 4 and (e) over bar <= n - 4. Let P(1) = < u(1), u(2),..., u(n)) and P(2) = (v(1), v(2),..., v(n)) be any two hamiltonian paths of G. We say that P(1) and P(2) are orthogonal if u(1) = v(1), u(n) = v(n), and u(q) not equal v(q) for q is an element of {2, n - 1}. We say that a set of hamiltonian paths {P(1), P(2),..., P(s)} of G are mutually orthogonal if any two distinct paths in the set are orthogonal. We will prove that there are at least two orthogonal hamiltonian paths of G between any two different vertices. Furthermore, we classify the cases such that there are exactly two orthogonal hamiltonian paths of G between any two different vertices. Aside from these special cases, there are at least three mutually orthogonal hamiltonian paths of G between any two different vertices. (C) 2009 Elsevier Ltd. All rights reserved.
Using Random Bit Authentication to Defend IEEE 802.11 DoS Attacks
(2009-09-01)
Lee, Ying-Sung
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Chien, Hsien-Te
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Tsai, Wen-Nung
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資訊工程學系
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Department of Computer Science
IEEE 802.11 networks are insecure. Wired Equivalent Privacy (WEP), the security mechanism used in 802.11, was proved to be vulnerable. IEEE 802.11i, the security enhancement, concentrates only on integrity and confidentiality of transmitted frames. Either version did not properly handle the network availability. Because management frames are not authenticated, {802.11, 802.11i} networks are susceptible to Denial of Service (DoS) attacks. In this paper, we designed a random bit authentication mechanism as a defense against DoS attacks. Random bits are placed into unused fields of the management frames. Access Point (AP) and station (STA) can then authenticate each other according to these authentication bits. The effectiveness of our mechanism is demonstrated through experimental results.
T-S Model-Based SMC Reliable Design for a Class of Nonlinear Control Systems
(2009-09-01)
Liang, Yew-Wen
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Xu, Sheng-Dong
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Ting, Li-Wei
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電控工程研究所
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Institute of Electrical and Control Engineering
This paper studies the robust reliable control issues based on the Takagi-Sugeno (T-S) fuzzy system modeling method and the sliding-mode control (SMC) technique. The combined scheme is shown to have the merits of both approaches. It not only alleviates the online computational burden by using the T-S fuzzy model to implement the original nonlinear system (since most of the system parameters of the T-S model can be offline computed) but also preserves the advantages of the SMC schemes, including rapid response and robustness. Moreover, the combined scheme does not require online computation of any nonlinear term of the original dynamics, and the increase in the partition number of the region of premise variables does not create extra online computational burdens for the scheme. Under the design, the control mission can continue safely without prompt external support, even when some of the actuators fail to operate. Meanwhile, both the active and the passive reliable designs are presented. The proposed analytical results are also applied to the attitude control of a spacecraft. Simulation results demonstrate the benefits of the proposed scheme.
增進連續輸入影像時車牌偵測效能之方法及系統
(2009-09-01)
王舜正
;
李錫堅
本發明提供一種增進連續輸入影像時車牌偵測效能之方法及系統,其係透過時空特性以減少搜尋空間來達成,包括一文字邊緣偵測模組、車牌字元候選區域偵測模組及重複區域偵測模組,首先從輸入系統之影像中偵測可能的文字邊緣區域,並擷取複數候選影像區域,再偵測一目前影像與一先前影像之候選影像區域內是否有重複區塊,並利用重複區塊來判斷該候選影像區域是否重複出現,若重複出現則不輸出為候選影像區域,可省略再次對目前影像中相同畫面進行的後續運算,因此本發明具有增進連續輸入影像時車牌偵測系統之運算速度,同時可避免因為連續出現的假車牌樣式造成的偵測錯誤一再發生,有提高準確率之優點。
Modeling Harmonic Distortions Caused by Nonlinear Op-Amp DC Gain for Switched-Capacitor Sigma-Delta Modulators
(2009-09-01)
Chen, Fu-Chuang
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Hsieh, Chih-Lung
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電控工程研究所
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Institute of Electrical and Control Engineering
Op-amps are crucial components in sigma-delta modulators (SDMs). As device dimensions and supply voltages continue to scale down, it is increasingly critical to determine a suitable op-amp dc gain. If the dc gain is set too high, then the op-amp consumes too much power; if the dc gain is too small, then nonlinear distortion becomes serious. However, there exists no efficient approach for selecting dc gains. In this brief, we propose to use a nonlinear function to model nonlinear op-amp dc gain curves. Then, this nonlinear function is employed to derive an SDM nonlinear distortion model as a function of SDM system parameters. The obtained SDM nonlinear distortion model can subsequently be used to compute the minimum required op-amp dc gain such that nonlinear distortions are kept under a tolerable value. The nonlinear dc gain curve model and the SDM nonlinear distortion model proposed in this brief are verified by behavior simulations and transistor-level simulations.
CLINICAL GENOMICS IDENTIFIES THE EXPRESSION OF HUMAN OVARIAN CARCINOMA
(2009-09-01)
Tsai, Meng-Hsiun
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Huang, Steve G.
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Tsaur, Shyh-Chang
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Hung, Yao-Ching
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Chiu, Sheng-Hsiung
Background: Human ovarian carcinoma is a silent killer. Most patients with human ovarian carcinoma are diagnosed in the advanced stages. Currently, no effective means of early detection are available. identifying genes that distinguish early cancers from normal tissue may provide insight to the initiation and progression of ovarian cancer. Methods: A large-scale gene expression profiling using 9,600 genes-complementary DNA array to study ovarian tumors was conducted. We analyzed 13 benign tumors, 22 invasive cancers (seven stage I and 15 stage III), and 16 normal ovaries. Cluster analysis revealed two major groups: the early-stage cluster that included 13 benign tumors and seven stage I cancers; and the late-stage cluster that included all stage III cancers. Results: There were 433 upregulated and 60 downregulated genes from the early-stage cluster, and 395 upregulated and 101 downregulated genes from the late-stage cluster. These genes showed altered functions for tumor/cancers, functions such as cell growth, cell cycle control, differentiation, signaling, apoptosis, ion transport, and morphogenesis. of most interest is the downregulation of nuclear receptor proteins. Differentially expressed genes between early-stage cluster and late-stage clusters were identified. We found 90 genes preferentially overly expressed and 165 genes relatively downregulated at late-stage cancers. The advanced cancer appears differently from early-stage cancer in cell growth, cell adhesion, hormone activity, morphology, and cell-cell signaling compared with benign or early-stage cancer. of particular interest are enzymes corresponding to pteridine biosynthesis, reported for the first time in this study. Real-time reverse transcription polymerase chain reaction showed that GCH1, KRT18, H3F3A, and MYBL2 were overly expressed in all cancer tissues, while MDFI, ARP3BETA, COL16A1, and MLN discriminated late-stage from early-stage cancers. Conclusion: The microarray provides valuable resources for comparing expression profiles of cancers at various stages and helps research the diagnosis and mechanism of ovarian cancer. [International journal of Gerontology 2009; 3(3): 163-169]
Design of Analog Output Buffer With Level Shifting Function on Glass Substrate for Panel Application
(2009-09-01)
Wang, Tzu-Ming
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Ker, Ming-Dou
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Chen, Sao-Chi
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電機學院
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College of Electrical and Computer Engineering
Two analog output buffers with level shifting function containing the digital-to-analog converter (DAC) circuit with gamma correction have been designed and verified in a 3-mu m low temperature poly-silicon (LTPS) technology, which are suitable for integrated on glass substrate for panel application. The new proposed circuits utilize the DAC with gamma correction of 3-V liquid crystal (LC) specification, but it can also drive the 5-V liquid crystal to meet the desired 5-V gamma curve without re-designing the DAC with 5-V gamma correction parameters.
Quantum squeezing and correlation of self-induced transparency solitons
(2009-09-01)
Lee, Ray-Kuang
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Lai, Yinchieh
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光電工程學系
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Department of Photonics
A general quantum theory of self-induced transparency (SIT) solitons is developed with nonlinear quantum effects of atoms taken into account. The quantization starts from the coarse-grain-averaged light-atom interaction Hamiltonian by which the quantum effects of ensemble atoms are modeled. The calculation of quantum properties is performed by the backpropagation method, which takes into account the contribution of the field continuum parts and the atomic fluctuations. The detectable squeezing ratio with a general homodyne local oscillator can be simulated for practical experimental realizations. Schemes for generating quantum correlation through SIT soliton interaction are also proposed and analyzed.