Giant Magnetoelectric Coupling Effect in MPLC System

 

論文發表人：張家銘 (加州大學洛杉磯分校機械曁航太工程研究所博士班)

 

http://spie.org/Conferences/Programs/07/ss/conferences/index.cfm?fuseaction=6526

 

利用理論預測與實驗驗證並行的方式，成功預測了磁電層狀複合系統之磁電耦合效應。本研究包含了六種不同配置磁電層狀複合系統，其中包括了二維及一維的幾何形狀以及縱向、橫向、平面向的初始磁化和極化方向。在利用等效磁電參數a量化了各個配置的磁電耦合效應後，我們發展了一個涵蓋了全範圍磁致材料的compliance、poisson's ratio、以及piezomagnetic coefficient ratio等材料性質的萬用排序空間圖。此外，磁電耦合效應實驗也印證了此理論模型的準確性。實驗包含了磁致材料的材料基本測試以及磁電層狀複合系統的應變和等效磁電參數a。結果證實了理論預測不僅在實驗應變分佈得到與實驗完美的吻合，在等效磁電參數a的比較上，理論曲線也成功地預測實驗結果。因此，藉由此研究成果，所有磁電層狀複合系統的效能皆可藉由這個空間圖加以預測。

 

A theoretical modeling and experiment effort have been performed to verify the magnetoelectric (M-E) coupling effect in magnetostrictive-piezoelectric layered composites (MPLC) system.  Six MPLC configurations are analytically modeled, including three field orientations, longitudinal, transverse, and in-plane, in both 1-D and 2-D plane geometries.  By determining the individual effects of configurations and material properties through modeling, a 3-D sequencing map covering the span of compliance, Poisson's ratio, and piezomagnetic coefficient ratio  of the magnetostrictive phases is developed to predict the homogenized M-E voltage coefficient, , curves.  To confirm the accuracy of the models, several MPLC systems have been fabricated and tested.  The results show good consistence for strain values and compatible trend for  curves.  By testing different MPLC system, the ordering of homogenized magnetoelectric voltage coefficient  of each configuration follows the 3-D  sequencing map.

Thermomigration of Pb in eutectic SnPb flip chip solder joints

論文發表人：歐陽汎怡(加州大學洛杉磯校區材料科學與工程博士班)

http://www.tms.org/Meetings/Annual-07/AnnMtg07Home.html

隨著半導體工業持續地追求高密度的輸入/輸出點和消費電子產品持續的小型化，覆晶封裝中的銲錫球的電遷移和熱遷移效用獲得越來越多的重視。當電流密度高到 10⁴ A/cm²時，覆晶封裝中的銲錫球的熱遷移效用是不容忽略的。熱遷移是一種由於溫度梯度所造成的質量移動。此現象是個不可逆的過程。一個小小1度C的溫度梯度跨過一個10微米的焊錫球就會產生一個每1公分1000度C的溫度差，這個溫度差非常的大。所以我們不可以忽略熱遷移的效用。此外，當電遷移和熱遷移一起發生在覆晶封裝銲錫球時，由於大的孔洞形成在銲錫球的陰極和熱端，快速的破壞機制發生 。在這個研究中，我門調查覆晶封裝中的共晶錫鉛銲錫球的熱遷移效用，從我們的結果發現，隨著鉛是主要的控制元素和擴散到銲錫球的冷端，我們觀察到鉛和錫的重新分布。另一個有趣的發現是，相對於傳統的Soret效用，我們發現沒有鉛或錫線性濃度差存在。此外，銲錫球的微結構分佈變的更細小，這個現在指出自由能和介面能的增加。最後，鉛的莫耳傳播值被計算為每莫耳25千焦。

Thermomigration is defined as mass flow driven by a temperature gradient. It is an irreversible process. A temperature difference of 1 ℃ across a solder joint with 10 μm in height will produce a temperature gradient of 1000 ℃/cm, which cannot be ignored. When electromigration is combined with thermomigration in flip chip solder joints, fast failure due to large void formation at the cathode and the hot end occurs. In this talk, thermomigration in flip chip solder joints of eutectic SnPb will be presented. Redistribution of Sn and Pb has been observed, with Pb being the dominant diffusing species and moving to the cold end. No linear concentration gradient in either Pb or Sn is observed, contrary to the classical Soret effect. The lamellar structure becomes finer after thermomigration, indicating an increase in lamellar interfaces and in free energy. The molar heat of transport of Pb has been calculated to be - 25 kJ/mole.

A Pneumatic Haptic Feedback Actuator Array for Robotic Surgery or Simulation

論文發表人：金志鴻 (加州大學洛杉磯分校生物醫學工程研究所博士班)

http://www.nextmed.com/mmvr_proceedings.html

機械輔助微創手術較一般內視鏡手術擁有極佳自由度的優點，因此成為新興的關鍵技術。 然而，在手術執行者缺乏實際觸覺回饋的情況下，僅能仰賴視覺來進行手術。 在機械手臂遠端控制介面加裝氣動式觸覺回饋致動器陣列能滿足手術進行中觸覺回饋的需求。 此裝置具有質量輕、體積小、成本低、以及通用於各種機械手臂等特點。 利用由矽膠薄膜所製成的氣動裝置，配合機械手臂尖端力的感應訊號，手術執行者的手部可以感應此裝置的力量傳遞，達到觸覺回饋的目的。 本研究探討了氣動裝置的大小（直徑0.75 ~ 2.00 mm）對手指觸感的靈敏度 ，藉此達到氣動裝置大小的最佳化。 初步結果證明了大於 1.00 mm 的裝置能提供較佳的觸覺反應。 此研究發明更可以普遍地應用在虛擬實境及義肢觸覺回饋等尖端領域。

Robot-assisted minimally invasive surgery (MIS) offers improved range of motion over standard laparoscopic techniques, but is characterized by a total loss of haptic feedback, requiring surgeons to rely solely on visual cues. Pneumatic tactile displays have many advantages, including low mass, low cost, compact size, and adaptability. A pneumatic haptic feedback actuator array has been developed that is suitable for mounting unto surgical robotic tools. The balloon actuators consist of spin-coated thin-film silicone membranes and molded substrates with cylindrical channels. Human perceptual tests were conducted on balloon diameters ranging from 0.75 to 2.0 mm to determine the optimal size that can be effectively detected. The control system was programmed to sequentially inflate a single balloon to one of the three levels, 100% (full hemispherical deformation), zero, 50% (half deformation), and 0% (no inflation). Blinded subjects (n=5) were asked to determine which of the two inflation levels was higher. Test results suggest that balloon diameters greater than 1.0 mm can deliver high detection accuracy. This indicates that pneumatic balloon-based actuation is a viable solution for generating haptic feedback. In addition to surgical applications, many other fields such as virtual reality-based simulators and prosthetics can benefit from this technology.

Development of Objective-Oriented Groundwater Models for Warren Subbasin, California

論文發表人：邱永嘉(加州大學洛杉磯校區土木研究所博士班)

 

http://www.agu.org/meetings/fm06/

 

為了要解決加州Warren子流域地下水資源管理優化的問題，一個可靠的數學模型用以預測不同的管理政策所帶來的結果是被需要的。現今，Warren子流域的部分地區已經被高濃度高的硝酸鹽所污染，因此，一個可減低硝酸鹽濃度，同時能夠持地下水位高度的計畫正被需求。美國地質調查所(USGS)根據現場探勘調查與野外記錄，為Warren子流域建構了一個概念模型，同時，利用觀測資料率定了概念模型中的參數。然而，要評估一個率定過之概念模型的可靠性仍然是件不容易的事情，因為真實世界的地質狀況往往是非常複雜，而且實際狀況通常是無法得知的。利用傳統的分析方法，通常無法得知概念模型架構上之不確定性變化對於地下水資源管理優化的衝擊。另外，判斷觀測資料的充足性與否也是另外一個難題，因為建構越複雜的模型，所需要的觀測資料越多。在這個研究中，提出一個新的概念來建構加州Warren子流域物件導向地下水模型。利用這個方法，可以藉由處理generalized inverse problem的過程，進而判斷概念模型的複雜度。概念模型的複雜度將取決於地下水資源管理模式的精確度（可靠性），在處理generalized inverse problem的同時，觀測資料的充足性與否也可以同時被決定。當建立一個可靠的概念模型當中，觀測資料不夠充足時，設計一個堅固且符合經濟效益的野外試驗將可經由處理generalized inverse problem的過程而得到。透過這個野外試驗將可獲得必要的觀測資料用以率定概念模型，最終得到一個可靠的概念模型。

 

In order to solve the optimal groundwater management problem for the Warren sub-basin, California, we need a reliable mathematical model to predict the results of different management policies. At the present time, certain parts of the basin are contaminated with high nitrate concentrations and a conjunctive use program is being developed to decrease the high nitrate concentration while maintaining the water table at the desired level. The USGS has constructed a conceptual model for the sub-basin based on available prior information and calibrated it with existing data. To assess the reliability of the constructed model, however, is not easy because the real structure of the groundwater basin is complex and generally unknown. The traditional methods of uncertainty analysis are unable to find the impact of the variability in model structure to the solution of the optimal management problem. To assess the sufficiency of the existing data is also difficult because more data are required to calibrate a more complex model. In this study, we use a recently developed methodology to construct objective-oriented models for the Warren sub-basin. With this methodology, the complexity of the model structure is determined by the accuracy requirement of the solution of the management problem and the sufficiency of the existing data can be judged by solving a generalized inverse problem. When the existing data are insufficient for constructing a reliable model for the specified management problem, a robust and cost-effective field experiment can be designed for collecting necessary data to make the calibrated model reliable. 

Scheduling Optimization of a Multiple Source Water Supply System

論文發表人：鄭蔚辰(加州大學洛杉磯校區土木研究所博士班)

 

http://www.agu.org/meetings/fm06/

 

本研究針對水資源系統發展一個全新的最佳配水及排程模式。模式中以供水節點、受水節點及供水路徑描述水資源之配水系統，取代以往以水源節點、需求節點及供水箭線所描述之配水系統。此種模式具有下述兩項優點: (1) 此模式可同時決定配水量、配水排程及供水之路徑。(2) 此模式用一組供水節點及受水節點描述水庫以反應真實世界中水庫不僅可以供水亦可受水之真實情況。因具上述之特性，此模式不僅可求出最佳由供水節點至受水節點之供水量，亦可求出最佳相對應之供水路徑。因此，此模式與一般模式僅能求解最佳箭線上之配水量不同，此模式所求出的最佳結果中包含了供水量、受水量、配水排程及在配水系統中詳細的配水資訊。在本研究中，我們採用一個假設的系統證明了此模式確實具備上述之能力，目前本研究正將此模式應用於實際的南加州之配水系統，此一實際配水系統供應南加州一千八百萬的人口所使用。

 

A new flow path model is developed for scheduling optimization of a water distribution system. The model characterizes a water distribution system by source nodes, receiving nodes, and flow paths. There are two advantages of this approach. First, linear constraints can be used to simultaneously determine the quantity and its associated flow path of water supply from a source node to a receiving node. Second, the model represents storage/reservoir as a source node as well as a receiving node simultaneously. This means that the model considers storage/reservoir as both a source and a demand at the same time to reflect the real-life situation. Therefore, the model optimizes not only the sources to each demand node but also their associated flow paths for supplying the water. This characteristic leads to the optimum solution that contains the optimal scheduling results and detailed information of the water distribution in the physical system. The quantity and its associated flow path in the water distribution system are explicitly represented in the results rather than merely an optimized total flow quantity in each link. In this study, a hypothetical scheduling problem is first used to test the proposed methodology. The results show that the flow path model has the ability to optimize both the quantity as well as the flow path. An application of the model is being made to the water distribution system of the Metropolitan Water District of Southern California which supplies water to 18 million people in Southern California.
DE: 1847 Modeling
DE: 1857 Reservoirs (surface)
DE: 1880 Water management (6334)
DE: 1884 Water supply
SC: Hydrology [H]
MN: 2006 Fall Meeting