Harmonic Holographic Microscopy Using Nano-Materials as Imaging Probes

論文發表人:謝佳龍( 加州理工學院電機工程學系博士班)
 
http://www.cleoconference.org/

 

「發光標識物」一直以來受到生物科學界的重視，因為透過適當的化學方法，這些「發光標識物」可以準確的標記在希望觀察的目標物上，使我們得以看到原本看不見的目標物的分佈。螢光標識物，例如綠螢光蛋白以及量子點，具有高亮度以及生物體相容的優點，所以已經被廣泛的使用。然而他們確有著光性質不穩定的缺點。我們提出使用從奈米粒子中產生的光二倍頻作為訊號的想法，希望藉此來取代螢光訊號。因為光二倍頻的機制中並沒有真實的能階躍遷，所以光二倍頻訊號是非常穩定的。除了穩定之外，光二倍頻擁有飛秒等級的快速產生機制，這讓我們有機會看到目標物的快速動態資訊。此外，當使用這些二倍頻奈米粒子作為發光標識物時，我們可以更好的方法來偵測他們。利用光二倍頻的同調性質，我們可以用全像術的技術來存取光二倍頻訊號。全像術的技術可以在一張影像中同時捕捉光的強度和相位。利用數位分析所取得的影像後，一張影像便可捕捉二倍頻標識物的三度空間分佈。在這篇論文中，我們分析光二倍頻奈米粒子的光學特性以及發展倍頻全像顯微術。二倍頻奈米粒子的三度空間分佈成功的被紀錄在一張二維影像之中。

 

Luminescent markers have attracted lots of attention in bio-science. With proper functionalization, these markers could be attached to the target of interest and make the target visible. Fluorescent bio-markers, such as green fluorescent protein or quantum dots, have been popularly used due to their outstanding brightness and biocompatibility. However they suffer from the deficiency of photo-stability. We introduce the idea of using second harmonic generation (SHG) from nanoparticles as the signal. These nanoparticles can be used as markers to label biological cells and allow for better detection techniques. In contrast to fluorescent markers, both limited by photobleaching, Second Harmonic Radiation IMaging Probe (SHRIMP) emits a stable signal owing to the lack of real energy state transition. The femtosecond response allows for observing fast dynamic process, such as protein conformation. Moreover the coherent nature of SHG enables us to record holograms at the doubled optical frequency. Since the hologram captures both amplitude and phase information of the optical fields, we could reconstruct the three-dimensional (3D) object field from one hologram. We demonstrated the harmonic holographic microscopy which captures 3D distribution of SHRIMP in one image.

Natural Language Processing and e-Government: Crime Information Extraction from Heterogeneous Data Sources

論文發表人：顧值豪 (加州克萊爾蒙研究大學 資訊系統與科技博士班)

 

http://www.dgo2008.org/

 

許多資訊可以用來幫助警方人員以阻止犯罪或是破案，但是過去這些資訊並沒有被完整的收集及利用。因為目前提供市民報案的方式有限，且並不是最佳的方式。警方人員沒有足夠的人力和時間來作完整的筆錄，再者受害者與目擊者擔心被報復或是暴露個人隱私，因此沒有到警局報案，這些都是資料無法完整收集的一些因素。我們目前利用自然語言處理和Cognitive interview (有關心理學的interview方式) 的技術來開發線上interview系統，提供市民報案。我們採用Open Source的工具GATE (General Architecture for Text Engineering)作為資料萃取的架構，並收集開發豐富的犯罪資訊相關的字彙，例如武器、交通工具、公司名稱、人體部位、衣服、個人物品…等資訊。我們開發了超過750條的資訊萃取規則，並加上自行開發的字串比對演算法來過濾重複的字串，並取得較佳的字串。為了要驗證和評估我們的演算法，我們從網路上收集了多樣化的犯罪報告。犯罪資料來源來自於新聞、警察公開資料、論壇、部落格和其他的來源。我們把資料分成警方的報告和見證人的報告。警方的資料一般是來自於警局和新聞內容，資料通常非常制式化，很多文法和拼字的錯誤都被更改，句子的架構也都重整過。至於見證者的報告是屬於最原始的資料，通常包含很多文法和拼字錯誤。我們利用precision和recall來評估整個系統的效能。我們並建立gold standard來加強評估的可信度。我們的系統處理警方的報告可以達到96%的precision和83%的recall。同時處理見證者的報告也可以達到93%的precision和77%的recall。為了改進系統處理見證者報告的效能，我們採用spell checker來矯正拼字錯誤，最後發現使用spell checker可以改進precision(從93%進步到94%)和recall(從77%進步到79%)。我們下一步將開始產生圖形和整理不同資料的來源，期望我們的系統可以取得更多資訊並幫助警方迅速的破案。

 

Much information that could help solve and prevent crimes is never gathered because the reporting methods available to citizens and law enforcement personnel are not optimal. Detectives do not have sufficient time to interview crime victims and witnesses. Moreover, many victims and witnesses are too scared or embarrassed to report incidents. We are developing an interviewing system that will help collect such information. We report here on one component, the crime information extraction module, which uses natural language processing to extract crime information from police reports, newspaper articles, and victims' and witnesses' crime narratives. We tested our approach with two types of document: police and witness narrative reports. Our algorithms extract crime-related information, namely weapons, vehicles, time, people, clothes, and locations. We achieved high precision (96%) and recall (83%) for police narrative reports and comparable precision (93%) but somewhat lower recall (77%) for witness narrative reports. The difference in recall was significant at p < .05. We then used a spell checker to evaluate if this would help with witness narrative processing. We found that both precision (94 %) and recall (79%) improved slightly.

A Flexible VLSI Architecture for Extracting Diversity and Spatial Multiplexing Gains in MIMO Channels

論文發表人:  楊家驤 (加州大學洛杉磯分校電機所博士班)

http://www.ieee-icc.org/2008/conference.html

球狀解碼演算法能在多重輸入輸出通道中達到最大概似效能，但它所需的計算複雜度卻大幅減少。這樣的複雜度化簡使得它相當適合於硬體實現。在這篇論文中，我們提出一個具有彈性架構能支援不同天線陣列與調變方式的球狀解碼器架構，進而充分利用多重輸入輸出通道中的多樣－多工增益。我們採用了多種訊號處理與電路技巧來進行硬體複雜度的降低。相對於直接實現的架構，甚至在不考慮支援多重載波的情況下，這個架構已經達到了20倍的面積減少。我們所提的彈性架構能支援2x2到16x16天線陣列，BPSK到64-QAM的調變方式，並且支援16-128載波。使用16MHz的頻寬，資料傳輸速率可高達1.5Gbps。採用90奈米製程，這個電路所需的晶片面積為0.5mm2。

The sphere decoding algorithm is able to approach maximum likelihood (ML) detection with significantly reduced computational complexity for multi-input multi-output (MIMO) communications. The computational reduction makes it attractive for hardware implementation. This paper presents a unified sphere decoder architecture that deploys diversity-multiplexing tradeoff in MIMO channels by taking advantage of the flexibility in the number of antennas and modulation schemes. Several signal processing and circuit techniques are constructively combined to reduce the hardware complexity: a 20 times area reduction is achieved even without interleaving of sub-carriers compared to the direct-mapped architecture. The proposed flexible architecture supports antenna arrays from 2x2 to 16x16, modulations from BPSK to 64-QAM, over 16 to 128 sub-carriers. The peak estimated data rate exceeds 1.5 Gbps over a 16 MHz bandwidth in just 0.55 mm2 in a standard 90 nm CMOS process.

Improved Coronary MRA Using Wideband SSFP at 3 Tesla with Sub-millimeter Resolution

論文發表人：李緒磊（南加州大學電機所博士班）

 

http://www.ismrm.org/08/

 

3T MRI 上的 SSFP 序列可提供冠狀動脈影像高訊噪比及高對比，然而 off-resonance 效應限制了此技術中的 TR 參數並降低可取得之空間解析度。Wideband SSFP 使用兩個不同的 TR 而產生交替出現的穩定態 (雙 TR 穩定態)，可抑制 off-resonance 並提升空間解析度。在此我們展示應用於 3T 平台之三維 navigated wideband SSFP 冠狀動脈影像，可在六分鐘內取得頻率編碼方向 0.68 毫米之空間解析度。Wideband SSFP 成功抑制 off-resonance 效應，顯示其改進在 3T 平台上高解析度無顯影劑冠狀動脈造影品質的能力。

 

Coronary artery imaging using SSFP at 3 Tesla exhibits high SNR and CNR, however off-resonance effects limit the TR and hence the achievable spatial resolution. Wideband SSFP sequences utilize an oscillating steady state to suppress off-resonance artifacts and therefore improve spatial resolution. Coronary artery images were obtained at 3T using three-dimensional navigated GRE, SSFP, and wideband SSFP sequences, with an in-plane resolution of 0.68 mm in the frequency-encoding direction. Wideband SSFP successfully suppressed banding artifacts, and is a promising approach for obtaining non-contrast, high-resolution coronary artery images at 3T with reliable image quality.

Coupled Global-Local Optimization Scheme for a Conjunctive-Use Project in a Desert Environment

論文發表人: 邱永嘉 (加州大學洛杉磯分校土木與環境工程研究所博士班)

 

http://typhoon.mines.edu/events/modflow2008

為減低因地方住戶化糞池產生的硝酸鹽入滲污染地下水系統，加州Yucca Valley的 Hi-Desert Water District (HDWD) 計畫建造一座新的污水處理廠用以解決此問題。經過污水處理廠處理過之廢水，將會注入一個人工濕地用以補注地下水。此設計歸類為地表水地下水交互使用之策略規劃。HDWD 希望可以尋找出最佳之地表水地下水交互使用策略，寄望有效控制地下水位，找出最佳的抽水井位置，同時符合加州州政府對於地下水補注之法規。
此研究，我們研發連結優化模型與數值模型的一個整合模型，此模型可找出最佳之地表水地下水交互使用的最佳策略。最佳策略的目標函數為最低之水資源供應成本，而限制條件則為，新抽水井之位置，抽水量之大小，可使用之地下水補注量，公共用水之供應量，以及地下水位高程之控制。根據設計，我們的優化模型將是一個非線性整數混合規劃模型。傳統的數值解法分為兩種，一為梯度法，二為全面性演算法。梯度法的計算速度非常快速，但容易陷入局部的最佳解，全面性演算法可以找出真正的最佳解，但計算速則度非常換緩慢。此研究，我們將連結全面性演算法與梯度法來找出真正的最佳解。連結全面性演算法與梯度法中，全面性演算法將使用基因演算法 (Genetic Algorithm) 找出接近真正最佳解的近似解，而後，再根據此近似解，用梯度法找出真正的最佳解。

 

To reduce the quantity of septic-tank nitrate from reaching the ground-water system, Hi-Desert Water District (HDWD) in Yucca Valley, CA is planning to construct a wastewater treatment plant. The treated wastewater will be recharged to the ground-water basin via percolation ponds as part of a larger conjunctive-use strategy, subject to state regulations (e.g. minimum distance, travel time). HDWD wishes to identify conjunctive-use strategies that control ground-water levels, meet regulations, and identify new production-well locations.
In this study we develop a simulation-optimization model that identifies optimal conjunctive-use strategies that minimizes water-delivery costs subject to constraints including pump capacities, available recharge water, water-supply demand, water-level constraints, and new-well locations. As formulated, the optimization problem is a mixed-integer, non-linear programming problem. Conventional optimization-solution methods include gradient-search and global-optimization schemes. Gradient-search schemes are computationally fast; however, they may only identify local optima. Global-optimization schemes identify the global optimum; however, they are computationally slow. In this work, we couple a global-optimization scheme (genetic algorithm or GA) with a gradient-search. The GA identifies a near-optimal solution and the gradient-search scheme uses the near optimum to identify the global optimum. Results indicate the global-local scheme is faster than GA alone and the global optimum can be identified.

A Proposed Flow Path Model for Scheduling Optimization of a Water Distribution System

http://content.asce.org/conferences/ewri2008/

 

論文發表人: 鄭蔚辰  (加州大學洛杉磯分校土木及環境工程研究所博士班)

 

本研究提出一適用於求解水資源管理系統之通用性最佳化模型：流路法。此模型可描述並求解現有最佳化模型所無法處理之水資源管理問題。一般來說，水資源管理之模型描述水資源問題的兩個方面：(a) 水的運送及交易介於送水者與受水者間之關係; (b) 在送水系統中，水的位置及運送路線。目前世界上所使用之最佳化模型多以網流為架構，因此只能描述上述兩方面中之一項，而無法在不簡化問題的情形下同時而完整地描述水資源管理之問題，此外因受限於網流架構及特性，許多水資源的管理規則及用水人問的協議難以被現有模型所考量。因此本研究針對水資源系統之特性提出一更為通用之最佳化模型：流路法。流路法之優點如下：(1) 是一通用之水資源最佳化模型，可同時描述並最佳化水資源的分配、運送、排程、交易、交換及調用；(2) 同時描述上述(a)、(b)兩問題時無需簡化系統；(3) 可做為及時操作之決策輔助工具。此研究應用流路法於南加州之水系統，並得到極佳的結果。

 

A flow path model is developed for scheduling optimization of a water distribution system. The model simultaneously describes a water distribution system in two parts: (1) the water delivery relationships between suppliers and receivers and (2) the physical water delivery system. In the first part, the model considers waters from different suppliers as multiple commodities. This helps the model to clearly describe water deliveries by identifying the relationships between suppliers and receivers. The physical part characterizes a physical water distribution network by all possible flow paths. The advantages of the proposed model are that: (1) it is a general methodology to optimize water distribution, delivery scheduling, water trade, water transfer, and water exchange; (2) no simplifications are made for either the physical system or the delivery relationship; and (3) it can be used as a tool for real-time decision making for scheduling optimization. The model optimizes not only the suppliers to each receiver but also their associated flow paths for supplying water. This characteristic leads to the optimum solution that contains the optimal scheduling results and detailed information of water distribution in the physical system. That is, the water right owner, water quantity and its associated flow path of each delivery action are represented explicitly in the results rather than merely an optimized total flow quantity in each link. The proposed model is first tested on two hypothetical water distribution cases. The results show that the flow path model has the ability to optimize both the quantity of each water delivery as well as the flow path. The model is being applied to the water distribution system of the Metropolitan Water District of Southern California (MWD), which supplies water to 18 million people in Southern California.

The Mandarin Chinese Particle Ei and its Projectability in Daily Conversation

論文發表人： 蔡宜妮 (加州大學洛杉磯分校應用語言學研究所博士班)

 

http://chinalinks.osu.edu/naccl-20/

 

本論文旨在探討語調揚升之中文語氣詞Ei在日常會話中表現出的現象與互動功能。Ei乃非詞彙的話語標記，書面表達上常以漢字「咦」或「誒」來標示。根據前人的研究，Ei為語氣詞，表達說話者內在迷惑、懷疑、驚訝的情緒。本論文將從會話分析的方法論入手，揭示語氣詞Ei在連續性對話中的出現語境，及其在對話過程中的互動預示功能。經過資料分析，本研究發現語氣詞Ei最常出現在以下兩種話語位置，具以下功能：（1）出現在句首，同後面緊接著問句連成一體：暗示問句的來臨，而且詢問將集中轉向在預期之外、非焦點之訊息；（2）出現在說故事或敘事過程的中間：預示、標誌將出現之故事線或論述將會有轉折或有預期之外的特性。綜合來說，本研究顯示語氣詞Ei在互動會話中扮演投射預示之功能，標誌將發生之對話將具有某種預期之外的轉折。根據以上的考察，本論文強調應該重視語氣詞的互動言談功能。

 

This paper presents an analysis from interactional point of view of the Mandarin Chinese particle ei, in a rising contour, in everyday conversations. In the previous studies, the particle ei, sometimes represented by the Chinese character 咦 or誒 , is commonly characterized as an interjection, showing speaker's inner state of mind, for example, puzzlement, doubt or surprise in this case and is regarded as an independent unit from the other parts of the speech. This study draws on conversation analysis and attempts to explore the sequential environments the particle ei regularly occurs and the interactional actions it accomplishes in talk-in-interaction. After examining the data, it is found that the particle ei seems to occur frequently in two distinguished environments: (1) occurring in a turn-initial position, prefacing questions and (2) occurring in turn-medial in a storytelling. Examples reveal that ei-marking seems to project a particular type of question that departs from the prior talk but switches focus, pursuing a new direction. The ei-marking in a storytelling, on the other hand, commonly introduces an unexpected twist, a twist constituting the climax of the story. It suggests that by using the particle ei, the speaker alerts the recipients to a switch or a twist and orients the talk s/he is about to produce as being unexpected and unanticipated. The finding implies that the particle ei does much more than showing speaker's inner state of mind: they accomplish interactional works, and the particles like ei should be approached from interactional point of view.

Over 1.5 μm photoluminescence from InAs quantum dots on patterned GaAs substrates by MOCVD

論文發表人：翁秉秀（新墨西哥大學光電所博士班）

 

http://iprm2008.org/

 

在這篇論文中，我們報告了以區域選擇性之奈米磊晶生長定址砷化銦量子點，並得到1.5微米以上之常溫光激發螢光頻譜的技術。我們首先探討了砷化銦量子點在砷化鎵金字塔結構奈米晶面上之選擇性結晶成核。此種方式成長出之量子點，其形狀和大小均較Stranski-Krastanow成長模式易於控制。砷化鎵金字塔結構是以金屬有機化學氣相沉積術在由二氧化矽定址之(001)砷化鎵基板上生長。圓形的定址區域是由干涉式微影術在二氧化矽上形成。砷化鎵金字塔結構由包含了{11n}、{10n}及(001)等三個晶面族的平衡晶體形狀組成。接下來的定址量子點結晶成核高度偏好(11n)平面，這是由於該平面提供較佳之能量最小化。在(11n)平面上形成之量子點的形狀十分容易預測，也十分均勻。這些砷化鎵平衡晶體形狀及高度晶面化之量子點均由高解析度之掃描式電子顯微鏡來分析。

我們並且展示了常溫下之光激發螢光頻譜，峰值最長可達1.65微米。低溫的螢光頻譜也證實了三維量子限制的存在。經由分析證實此長波長砷化銦量子點螢光頻譜是由於增大的量子點尺寸，以及減小的量子點內之應力兩者共同促成。量子點的大小可以在不影響密度的狀況下，以單一的生長條件（生長時間）來控制。而應力減小則可能是來自於在量子點生長平面邊緣的部份應力降低、生長平面傾斜、以及量子點尖端的應力釋放。

 

In this paper, we report room-temperature (RT) photoluminescence (PL) emission above 1.5 μm from InAs patterned quantum dots (PQDs) by selective area nano-epitaxy.  The selective InAs QD nucleation on nano-faceted GaAs pyramidal facets is explored.  This technique of QD growth enables better control of QD shape and size, than is possible with the Stranski-Krastanow growth mode.  The GaAs pyramids are formed by metal-organic chemical vapor deposition (MOCVD) in patterned SiO₂ mask on a (001) GaAs substrate, where the circular openings are formed by interferometric lithography.  The GaAs pyramids are characterized by well-defined equilibrium crystal shapes (ECS) defined by three crystal plane families including {11n}, {10n} and (001).  Subsequent PQD nucleation on the GaAs pyramidal facets is highly preferential towards the (11n) planes due to superior energy minimization and the shape of the QDs on the (11n) planes is also highly predictable and uniform.  The GaAs ECS pyramid and highly faceted PQDs are examined using high-resolution scanning electron microscopy (HRSEM). 

We also demonstrate strong RT PL emissiom from these InAs PQDs up to 1.65 μm.  The low temperature PL confirms the existence of three dimensional quantum confinements.  Analyses show that the long wavelength emission from InAs QDs is contributed by both the enlarged QD size and reduced residual strain inside the QD.  The size of QDs can be controlled with a single parameter, the growth time, without affecting the density of QDs.  The strain relaxation is likely due to the possible partial strain relaxation of the PQD at the edges of the GaAs pyramid facets where it nucleates, tilt of the growth plane, and the fully relaxed InAs matrix near the tip of the large PQDs

Parylene Electrothermal MEMS Drug Delivery Valve

論文發表人：李柏穎 (南加州大學電機所博士班)

 

http://www.acs.org/

 

我們提出一個用於供藥之電熱驅動, 拋棄式, 低功率C型對聚二甲苯微機電閥.  這個常關閥是的一個微噴注幫浦的一部份可用於快速供給輻射染劑進入動物血液循環系統.  這個低功率超輕重量的閥實現腦神經顯影術於自由活動且無束綁的動物.  在此我們說明此裝置的設計與製造的方法.  這個閥包含安裝在兩個導管間的一個對聚二甲苯/白金/對聚二甲苯的複合薄膜且由微機電系統技術所製造.  我們也在實驗室對此閥的功能進行測試.  白金薄膜的電阻率溫度常數也經過校正且得到其對電流之熱反應.  電流會導致閥的薄膜鎔化進而打開流通孔道.  測試結果顯示本裝置消耗約25至50微瓦的功率且電流約在7到20 微安培間.  最後, 我們將測試完畢的閥裝置與微噴注幫浦組合完成系統整合並討論結果.

 

We present an electrothermally-activated disposable, low-power Parylene C MEMS valve for drug delivery.  The normally-closed valve is part of a microbolus infusion pump used for rapid delivery of a radiotracer into the circulation.  This low-power, light-weight valve enables neuroimaging of brain blood flow in freely-moving untethered animals.  The design and fabrication method are presented.  The valve consists of a Parylene C/Pt/Parylene C membrane mounted in a catheter and was fabricated using microelectromechanical systems technology.  Valve performance was characterized in benchtop experiments.  The temperature coefficient of resistivity of the Pt thin film was calibrated and the thermal response to applied current was obtained.  Current application induces thermal degradation of the valve membrane to create a fluid flow path.  Opening powers of 25-50 mW were obtained for operating currents of 7-20mA.  Finally, the assembly technique to incorporate the valve in to the microbolus infusion pump is described.

Nano Electronic Nose: A Hybrid Nanowire / Carbon Nanotube Sensor Array with Integrated Micromachined Hotplates for Sensitive Gas Discrimination

論文發表人: 陳柏江(南加州大學)

 

http://mrsspring2008.abstractcentral.com/planner.jsp

 

本複合型奈米化學感測器陣列是由I2O3奈米線， SnO2奈米線， ZnO奈米線，以及奈米碳管所組成，加上微機電加熱板的輔助，我們成功的展示了新一代的化學感測器用於分辨各種重要的化學氣體。 本研究的重點分述如下:1. 江三種不同的金屬氧化物奈米線與奈米碳管結合在同一個感測晶片上；2. 將微機電加熱板應用在感測晶片上，使得我們可以準確的控制溫度；3. 利用 Principal component analysis (PCA) 分析所得的數據；進以得到相對應的感測圖譜；
本感測陣列能偵測許多重要的工業氣體在不同的濃度和溫度下，例如Hydrogen、Ethanol以及Nitrogen Dioxide；並且成功的展示了對於不同氣體的分辨能力，透過本感測器陣列，我們能獲得到一個有趣的"氣味資料庫"用以分辨許多重要的化學氣體。此外，PCA的分析結果展示了本陣列對於三種被測試的化學氣體的強大分辨能力，并且詳細分析了化學感測結果。結果顯示，將奈米碳管加入金屬氧化物化學感測器提供了強大的分辨力。本本複合型奈米化學感測器陣列有極大的潛力偵測及分辨各種各樣的氣體，包括炸藥和神經毒氣。

 

A novel hybrid chemical sensor array composed of individual In2O3 nanowires, SnO2 nanowires, ZnO nanowires, and single-walled carbon nanotubes (SWNTs) with integrated micromachined hotplates for sensitive gas discrimination was demonstrated.  Key features of our approach include the integration of nanowire and carbon nanotube sensors, precise control of the sensor temperature using the micromachined hotplates, and the use of Principal Component Analysis (PCA) for pattern recognition.  This sensor array was exposed to important industrial gases such as hydrogen, ethanol and nitrogen dioxide at different concentrations and sensing temperatures, and an excellent selectivity was obtained to build up an interesting "smell-print" library of these gases. Principal component analysis of the sensing results showed great discrimination of those three tested chemicals, and in-depth analysis revealed clear improvement of selectivity by the integration of carbon nanotube sensors. This nano electronic nose approach has great potential to detect and discriminate a wide variety of gases, including explosives and nerve agents.

Optical Patterning of Three-Dimensional Carbon Nanotube Microstructures

 

論文發表人：洪緯璿 (南加大材料科學所博士班)

 

http://www.aps.org/meetings/march/index.cfm

 

我們發表一個利用光學非接觸的方法去製作3D微結構於奈米探管上。這方法是利用一1.25微米直徑大小雷射光束，去製做圖形畫結構於高密度垂直生長的奈米探管森林中。我們利用了拉曼光普以及電子顯微鏡去決定燃燒過程的所需的最小雷射能量以及所製作的結構深度。配合高精度的移動平台，我可以利用此方法快速的製作3D的微結構於奈米碳管上。經過雷射的表面處理，我們發現的一些有趣的現象 例如：結構根部被切割 表面密度的改變 以及為奈米粒子的成長行為。這些發現都有助於我們對燃燒製程的理解。由於方法這成無需利用任何的黃光製程有助於擴展奈米碳管的應用於一些對於黃光製程有限制的領域。

 

We present an optical, non-contact method for patterning three-dimensional carbon nanotube microstructures. In this method, a 1�m diameter focused laser spot is used to burn patterns in dense arrays of vertically grown multiwalled carbon nanotubes. The threshold for laser burnout and the depth of burnout are determined by Raman spectroscopy and scanning electron microscopy. Using a high precision translation stage to control the position of the laser spot on the sample, we create several 3D patterns to illustrate this method's potential use for the rapid prototyping of carbon nanotube microstructures[1]. After laser surface treatment, we observe undercut profiles, changes in nanotube density, and nanoparticle formation, which provide insight into the unique evolution of the nanotube microstructures during the burnout process. This non-lithographic method provides new opportunities for chemically sensitive applications of nanotubes and expands their possible applications into new areas.

 

 

M82 at 7mm

 

論文發表人: 蔡肇偉(加州大學洛杉磯分校物理與天文系博士班)

 

We present VLA 7mm radio continuum images of M82 at arcsecond and sub-arcsecond resolutions. The 7mm emission is dominated by the thermal free-free radiation, allowing us to trace the O star population at two different size scales. We identify 4 sources with rising spectra and sizes of few pc across, and argue that they are compact HII regions with ne ~ 104 cm3. We see unusual extended regions of relatively high emission measure; the high pressure in M82 may allow them to exist. The correlations between the distributions on arcsecond scales of thermal free-free (7mm), PAH feature (Spitzer IRAC 8 micron), CO(1-0) and HCN(1-0) emission are discussed.

 

我們在此發表使用美國國家無線電天文台之VLA無線電望遠鏡觀測「梅西爾八十二」星系於七毫米波段的觀測結果。我們測量得七毫米波長的無線電射線主要來自於重質量恆星週遭的游離氫雲氣所發出的自由電子輻射，因此使得我們可以利用七毫米波的圖像來追蹤重質量恆星的分布。在次角秒解析度之「梅西爾八十二」星系無線電波圖像中，我們發現了四個數光年大小之氫離子雲區，其具有較一般氫離子雲區高出十倍以上的自由電子密度。我們並發現了數個奇特的七毫米波無線電延展放射源，約數十光年大小，其存在需要梅西爾八十二星系內部之高壓環境才可能產生並維持。我們並討論七毫米波自由電子輻射、多環芳香烴分子之紅外線輻射、一氧化碳分子輻射、以及氰化氫分子輻射在空間上分布的相關性。

Travel Time-Based Equilibrium of High-Occupancy-Vehicle and General-Purpose Lane Allocation

論文發表人: 鍾智林 (加州大學爾灣分校土木所博士班)

 

http://www.trb.org/meeting/2008/default.asp

 

高乘載車道與一般車道使用有限的道路空間，彼此存在競爭關係。本研究提出兩種方法評估合理的車道分配，分別為"車輛旅行時間均衡法"以及"旅客旅行時間均衡法"。前者從車輛的角度分析高乘載車輛與非高乘載車輛之旅行時間關係，後者從旅客的角度分析高乘載車道與一般車道之旅行時間關係，兩種方法可導出不同的高乘載車輛與非高乘載車輛之均衡速度曲線與曲面。由加州橙縣405州際道路的案例研究結果顯示，1個高乘載車道搭配4~5個一般車道的現況配置，高乘載車輛整個旅次鍊的旅行時間較長，相當於處罰共乘者而鼓勵單獨開車﹔車道配置若調整為2個高乘載車道搭配3~4個一般車道，較符合以旅行時間為基礎的車道均衡分配。文末建議結合先進運輸管理系統以及本研究所提的均衡法，透過即時車道調整措施以促進交通公平性。

 

Due to limited road space, HOV and general-purpose (GP) lanes are usually in a trade-off relationship. This study proposes two approaches to assessing fair shares of HOV and GP lanes, namely vehicle travel time equilibrium and passenger travel time equilibrium. The former is on a vehicle basis that equilibrates travel time of HOV and non-HOV; the latter is on a passenger basis. Equilibrate speed surfaces and curves are derived via the approaches. A case study using traffic data of I-405 freeway in Orange County, California, shows that the existing lane allocations, 1 HOV + 4~5 GP lanes, are punishment to HOV, and switch of a GP lane into the second HOV lane would make the HOV reasonably competitive and equilibrate in terms of passenger and/or vehicle travel time. By joining advanced transportation management systems, traffic equity is anticipated with development of real-time lane adjustment that applies the concepts of travel time equilibrium.

Freight Transportation Derivatives Contracts: State of the Art and Future Developments

論文發表人: 蔡玫亭 (加州大學爾灣分校土木所博士班)

http://www.trb.org/meeting/

當今貨物運輸紛紛實行「瘦身」(lean) 與需求回應(demand-responsive)物流系統，即使在運輸需求不確定的情況，仍然高度要求貨物運輸的速度、正確性及可靠性。因此，貨物運輸產業極需新的方法管理運輸合約。實質選擇權(real option)理論之應用就是規避運輸容量及運輸成本不確定性的有效方法之一。海洋運輸是目前唯一使用此類衍生性合約的運輸產業。本研究目的是針對衍生性合約進行整體性探討，我們從海運業衍生性合約市場之發展情形開始，探究海運業市場經營之成敗，根據其經營經驗，就目前美國貨物運輸龍頭產業—卡車業，提出卡車運輸衍生性合約之建議，並深入分析引進卡車選擇權合約市場之並要條件及潛在利益。

In lean and demand-responsive logistics systems, orders need to be delivered rapidly, accurately and reliably, even under demand uncertainty. Increasing demands on the industry motivate the introduction of new methods to manage transportation service contracts. One way to hedge transportation capacity and cost volatility is to use real options. To date, ocean transportation is the only area of transportation where this type of contract, also known as a derivatives contract, has been applied. The purpose of this paper is to provide an overview of freight transportation derivatives. We start by reviewing the development of derivatives markets in the maritime industry. Based on our findings and on the experience accumulated in that industry, we investigate the adoption of derivatives contracts in trucking, which is the dominant freight transportation mode. This paper provides an understanding of the necessary conditions and potential benefits for the emergence of a market for truckload options.

Minimizing Departure Time for Outgoing Trucks in a Crossdock

論文發表人: 王建富 (加州大學爾灣分校運輸科學博士班)

 

http://www.trb.org/meeting/

 

越庫碼頭(Crossdock)在供應鍊營運中扮演著重要的角色。由於在供應鍊環節中某些活動對於減少運輸前置時間的要求提高,例如及時物料供給、客製化生產以及中途併貨等策略,使得縮短貨品在越庫碼頭的處理時間顯得亦形重要。在本研究中,我們針對等待入庫卸貨的貨車加以排程,以使得貨品在等待出庫的貨車之等候時間最少,亦即使其停留在越庫碼頭的時間最短。我們採用了動態模擬的模式來比較三種排程策略:先到先服務(first-come-first-served) 、look-ahead 以及 leave-early。我們發現當採用leave-early策略及在配備有四個卸貨碼頭與四個出貨碼頭的越庫碼頭時,相較於其他兩種策略,我們的策略能為貨物節省最高達百分之十二等候時間或者最高達百分之四的整體轉運時間。

 

Crossdocks play important roles in supply chain operations. Due to the need to decrease transportation leadtime to coordinate with other supply chain activities such as just-in-time, make-to-order or merge-in-transit strategies, the importance of shortening total processing time at crossdocks has increased. In this research, we schedule waiting inbound trucks in such a way to allow for the early departure of outgoing trucks.  This minimizes the time freight spends in a crossdock. We use a dynamic simulation model to compare the performance of first-come-first-served, look-ahead and leave-early policies under different truck inter-arrival times and crossdock layouts. From our simulation results, we find that our leave-early algorithm can save up to 12% on freight wait time in outgoing trucks and 4% on total time relative to the other policies under a 4 receiving doors and 4 shipping doors layout. In addition we suggest guidelines for choosing scheduling algorithms in different situations.

PARYLENE COATED SILICON PROBES FOR NEURAL PROSTHESIS

論文發表人：黃奎瑞 (加州理工學院電機博士班)

http://dellfc01.acae.cuhk.edu.hk/ieee-nems/nems08/index.html

Silicon neural prosthetic probes require reliable sensing electrodes able to access deep cortical structures without breakage. However, manufacturing limitations have prevented a strong and biocompatible silicon electrode array from reaching this goal. We here demonstrate the first high-density, parylene-coated silicon probe (1.2 cm long) with micro-fabricated electrodes that is able to be inserted in vivo without failure. This work also presents new experimental results for array shank deflection testing, lifetime soak testing as well as the in vitro electrical characterization of the gold and platinum micro-electrodes. These results allow us to optimize the geometry and treatment for both the silicon probe and the metal electrodes.

電子神經探針系統所使用的矽探針需要一個能進入深表皮層的同時又不會遭到破壞的可靠檢測電級。然而，製作過程的局限大幅限制了一個堅固且生物相容的電級列陣達到這樣的目標。在本文中，我們展示了第一個高密度且經parylene(聚對二甲苯基) 包覆的矽探針並以微小技術製造的電極。此一探針能夠成功地使用在活體穿透實驗。此外，本文也提出了新的實驗結果；包括了探針列陣偏折測試、浸泡測試、以及金和白金微電極的體外電子特性描述。這些實驗結果可讓我們對於矽探針及金屬電極在形狀、排列、以及製作程序上做到最佳化。