All-Dielectric Wireless Receiver

論文發表人: 徐家仁 (加州大學洛杉磯分校電機所博士班)

 

http://www.ims2007.org/

 

本篇論文提出一種新式微波接收器,隨著電磁脈衝武器的威脅日益升高,傳統的射頻及微波接收電路缺乏適當的保護機制,本篇論文結合介電共振天線和光電調變器的原理,展示了一種新型的微波接收器,整個接收器是由全介電材料組成,所以可以承受高功率電磁脈衝的干擾而不被破壞,光學原理的使用更進一步隔離了接收器前端和後端電路,讓電磁脈衝產生的高瞬間電壓無法傳遞到接收器後端,進而確保了後端電路的安全,初期的實驗結果證明了這類新型的接受器可以達到4.3´10^-3 V/m∙Hz^1/2的電場靈敏度

 

High Power Microwave (HPM) weapons and other sources of  intense microwave power pose a growing threat to modern RF receivers. To address this problem, an all-dielectric photonic-assisted receiver is proposed and demonstrated. The device consists of a dielectric resonator antenna that concentrates and feeds the signal onto a resonant electro-optic field sensor. The absence of metal interconnects and the charge isolation provided by the optics removes the "soft spots" in a traditional receiver.  In the proof-of-concept experiment, detection of C band electromagnetic signal at 7.38 GHz with a sensitivity of 4.3´10^-3 V/m∙Hz^1/2 is demonstrated. 

Broadband Quadrature Hybrid Design Using Metamaterial Transmission Line and Its Application in the Broadband Continuous Phase Shifter

論文發表人: 李振榮(加州大學洛杉磯分校電機工程博士班)

 

http://www.ims2007.org/

 

本篇論文主要是討掄一個寬頻正交混合器的設計. 此設計最主要是利用寬頻威爾金森功率分配器和利用超穎物質傳輸線來達成的寬頻相差去完成. 將威爾金功率分配器和超穎物質分配器結合後, 對於相差90°±5°和0.48功率差的公差來說, 其成效可以達到67%的頻寬. 除此之外, 完整的四端寬頻證交耦合器需要再利用一個功率合成器. 在此, 對於相差90°±5°和0.48功率差的公差來說, 其效果也可以達到67%的頻寬. 為了證明所提出的正交寬頻混合器的可應用性, 我們用一個利用向量加法的連續相移器去證明其潛力.

 

This paper presents a broadband quadrature hybrid which makes use of the broadband power division properties of conventional Wilkinson power splitters along with broadband phase difference achieved using metamaterial based delay lines. The bandwidth of the 90°±5° phase difference and 0.48dB power difference between the outputs of the Wilkinson power splitter and metamaterial delay line combination is 67%. The full four-port coupler is formed employing an additional combiner. A phase/power difference between the hybrid outputs of 90°±10° and 1.2dB, respectively, are observed over the same 67% bandwidth. To demonstrate the applicability of the proposed broadband quadrature hybrid, a continuous phase shifter which is based on the vector sum method is tested.

Dream Freely/Freedom Dream:International Students in the USAmerican Academic nation

論文發表人: 林茵 (亞利桑那州立大學劇場研究所博士班)

 

http://theatre.umn.edu/ptoconference/index.htm

http://www.ptoweb.org/

 

本研究是以夢境來呈現台灣學生在美國求學與生活的經驗。以劇場中常用的說故事手法來呈現國際學生內心的掙扎與反省。 長久以來，許許多多的國際學生來到美國追尋一個自我實現的夢想。他們渴望在不分國度的學術界裡被接納成為成功的學術界公民。然而，在許多的多元文化教室裡，國際學生常因為文化差異、語言隔和、權力分配不均等等因素在激烈的學術競爭中面對不公平的競爭。夢境常是真實生活的寫照。人們往往藉由夢境反映、反思、反抗在現實生活中的點點滴滴。夢的形式是片段、破碎、與不連貫的，這些特質是反抗者對抗權力與壓迫時常使用的手段。這個表演式的民族誌研究訪談了在亞歷桑那州立大學就讀的台灣留學生，以戲劇特有的專業技法蒐集個人的故事、感受、表情、肢體語言等等具表演力的非平面文字資料，並以戲劇演出呈現研究成果。主要應用的戲劇理論與實務方法是巴西劇場大師波瓦的"被壓迫者劇場"中的影像劇場、論壇劇場等等方法。研究成果與發表是一個單人的演出，以不同的夢境呈現國際學生如何在挫折中追求成功之道。演出是由六個夢境組成。分別呈現留學生與家鄉、與食物的關連性。更呈現留學生涯中在文化間、土地間不斷轉換的心境。這個演出更是希望帶出對話。將發表會場轉成一個多元文化的課堂，使觀眾皆可暢談自身的多元文化學習經驗。以演出刺激大家的思考，藉以實踐一個理想的多元學習空間。

 

     Dreams are a space for people to meet themselves.  Through dreams, people re-imagine/replay/reformat their lives.  Dreams trouble the definitions of citizenship, (i.e. locality, privileges, rights) through fragmentation, instability, and nonlinearity.  In a dream, one owns the agency to create a safe zone to confront the oppressor as well as subvert the situation s/he encounters in real life.  For many decades, international students have come to the "Land of the Dream,"  the United States, to pursue their dreams of success as citizens in the academic nation. However, without sharing the ownership in such a multicultural classroom, international students often lose their voices by being at the bottom of the power hierarchy in academic society, due to language barriers, cultural differences, etc.

     In my project, I apply dreams as a tool to approach my research about international students' lives in the U.S. As an international student from Taiwan, I constantly experience a feeling of displacement and off-balance in my daily and academic life.  In this Performance Ethnography, I employ dreams as a metaphor for the negotiation between international students and power plays that occur within Western academia.  The negotiation takes place in the conversation between the dreamtexts and monologue I created based on my research data.  I also employ Theatre of the Oppressed and Creative Drama techniques to gather research data in workshops with international students at ASU. The dreamtexts reveal the relationships between international students and their hometowns/ families/ foods.  It also presents the class dynamics of an internationalized classroom.  By sharing their dreams about gaining ownership in the classroom through theatre, I aim to redefine citizenship in the academic nation.  I also perform my research as an "art-based civic-dialogue" by using the performative dreamtexts to dialogue with the audience as participants in the USAmerican academic nation.

 

Real-Time Transfer Efficiency Monitoring for Wastewater Aeration Systems

論文發表人: 呂紹元(加州大學洛杉磯分校土木與環工系博士班)

http://www.efficient2007.com/

本研究針對一般民生污水的處理發展了一套即時監測系統，並用以進行曝氣時能量使用與操作成本的分析：曝氣是民生廢水處理系統中最為耗能的一個單元操作流程。為了增進氧氣傳送速率，細氣泡型曝氣盤(fine-bubble diffusers)受到廣泛的採用。然而由於處理污水中充滿著各種污染物及微生物構成的活性污泥，這類的曝氣盤的氣孔在長時間的使用中很容易被堵塞；此一現象將大大減低曝氣盤的效果與使用壽命。堵塞的情形隨著污水處理廠的操作而有不同，且一般皆由人工清洗的方式來恢復處理效果；而清洗會造成操作成本的提高。本研究提供一種即時監測的方法來量化曝氣盤受到污泥所堵塞的情形，並藉以判斷何時清洗曝氣盤最符合經濟效益。逸氣測試方法(off-gas test)是現今測試氧氣傳輸效率最快且正確的方法之一，而本研究針對此測試法進行改良並使之成為一即時監測/紀錄的系統。實地測試的結果發現：1.清理前後氧氣傳輸效率確有提升 (15%→18%)；2.即時監測結果與長期觀測結果相符；3.此監測法可提供正確並即時的氧氣傳遞資訊，未來當可用於曝氣馬達的回饋控制系統中以提高能源使用的效率。

 

Aeration is the most energy intensive unit operation in municipal wastewater treatment. To improve oxygen transfer rate, fine-pore diffusers have been wildly applied in aeration practice. However, during operation, this type of diffusers suffers from fouling and scaling problems, which rapid decline in performance and significant increase in energy costs. Diffusers must be cleaned periodically to reduce energy costs. The cleaning frequency of diffusers is site-specific, and is shown by the reduction of oxygen transfer efficiency (OTE) with time in operation. Off-gas testing is the only technique that can measure real-time oxygen transfer efficiency. This paper presents time-series of off-gas testing measurements and their applications, which show the potential for full-scale implementation of energy-conservation practices. Our results include the real-time prediction of plant load and alpha factors from off-gas testing, as well as the quantification of the increased energy costs for aeration. Our off-gas analyzer is being used to develop an aeration efficiency monitoring protocol, and an aeration feedback control system for air blowing units.