Joint Optimization of Transceivers with Decision Feedback and Bit Loading

論文發表人: 翁竟智(加州理工學院電機系)

 

http://www.asilomarssc.org/

 

收發器的優化問題的MIMO渠道在過去被考慮過使用線性接收器以及與判決反饋（有限元）接收器。聯合優化比特分配，先行編碼器，並均衡在過去被認為只用於線性收發器（收發器與線性先行編碼器和線性均衡器） 。也有人指出，利用有限元甚至沒有比特分配的一般結果性能更好，線性收發比特分配。本文提供了一個一般性研究這個的收發器與迫零的制約因素。這是正式表明，當比特分配，先行編碼器，並均衡共同優化，線性收發器和收發器與有限元有相同的性能，即發射功率是相同的某一比特率和錯誤概率。發展本文是基於廣義三角分解(GTD)。這將是表明了廣泛的GTD階級為基礎的系統的最佳解決有限元問題，比特分配。在特殊情況下，線性收發最佳比特分配將成為其中一個解決辦法。

 

The transceiver optimization problem for MIMO channels has been considered in the past with linear receivers as well as with decision feedback (DFE) receivers. Joint optimization of bit allocation, precoder, and equalizer has in the past been considered only for the linear transceiver (transceiver with linear precoder and linear equalizer). It has also been observed that the use of DFE even without bit allocation in general results in better performance that linear transceivers with bit allocation. This paper provides a general study of this for transceivers with the zero-forcing constraint. It is formally shown that when the bit allocation, precoder, and equalizer are jointly optimized, linear transceivers and transceivers with DFE have identical performance in the sense that transmitted power is identical for a given bit rate and error probability. The developments of this paper are based on the generalized triangular decomposition (GTD) recently introduced by Jiang, Li, and Hager. It will be shown that a broad class of GTD-based systems solve the optimal DFE problem with bit allocation. The special case of a linear transceiver with optimum bit allocation will emerge as one of the many solutions.

Per-Antenna Power Constrained MIMO Transceivers Optimized for BER

論文發表人: 翁竟智(加州理工學院電機系)

 

http://www.asilomarssc.org/

 

本文討論線性收發器的優化問題.在多載波多輸入（ MIMO ）的渠道，每個天線功率的限制。 由於在實際執行每個天線是有限的其單獨配備功率放大器，本文採用更支現實的每天線權力的制約，相反傳統的總和權力制約發射機天線。假設完美知識的渠道在發射器和接收器，優化問題可以轉變成一個半正定問題 ，是可以被解決的凸優化工具。此外，若干客觀職能的MIMO系統，包括平均位誤差率，也可以用此方法解出。

 

This paper considers the linear transceiver optimization problem for multi-carrier multiple-input multipleoutput (MIMO) channels with per-antenna power constraints. Because in practical implementations each antenna is limited individually by its equipped power amplifier, this paper adopts the more realistic per-antenna power constraints, in contrast to the conventional sum-power constraint on the transmitter antennas. Assuming perfect channel knowledge both at the transmitter and the receiver, the optimization problem can be transformed into a semi-definite program (SDP), which can be solved by convex optimization tools. Furthermore, several objective functions of the MIMO system, including average bit error rate, can also be optimized by the introduction of the majorization theory.

Authentic and Reliable Suspended Solids Measurement Processes for Stormwater

http://www.envicenter.com/iwa2008/web/index.php?option=com_frontpage&Itemid=1

 

論文發表人: 詹立成 (加州大學洛杉磯分校土木及環境工程研究所博士班)

 

總懸浮固體需樣品混合均勻，前期研究低速下易造成實驗誤差，攪拌強度取決於攪拌過程，如人工，機器或其他拌勻方式，及以人工或試管分次樣品，機器自動分次樣品，未定義方式易造成誤差。本研究分析實驗偏差值並且建立最好實驗過程。

實驗依據水及廢水處理標準程序執行，以微矽珠與沉積土為實驗物質，方式有搖勻或拌勻後人工及試管分次樣品，加入緩衝板或方形容器後人工及試管分次樣品，及機器拌勻試管分次樣品。

搖勻或拌勻試管分次樣品較人工分次樣品準確，由於人工分次樣品較難以得到準確容量。拌勻較搖勻準確。以試管分次樣品及250RPM攪拌速度，機器拌勻於直徑小於90毫米顆粒獲得74%回復率，相較直徑大於125毫米顆粒只得8%回復率，歸因較大顆粒沉積於底部。增加攪拌速率會導致渦流現象產生而攪拌不完全，加入緩衝檔板或方形容器可減少渦流現象，但顆粒卻於燒杯角落沉積。人工傾倒較難反應實際濃度，搖勻無法使顆粒分布均勻，導致次樣品濃度不一。加入緩衝檔板或方形容器並不適用於攪拌。在700RPM攪拌速度，小於250毫米懸浮微粒可得到超過95%回復率，大於250毫米可得到72.4%回復率。標準燒杯使用700RPM以上攪拌速度的拌勻方式，與使用試管分次樣品可得到最準確回復率。

 

The total suspended solids (TSS) standard method requires well-mixed samples for analysis. The previous work has shown that TSS results are unreliable below certain mixing speed. The required mixing intensity depends heavily on the mixing processes. The mixing method can be shaking, stirring, or even not specified. Transferring subsamples can be pouring, pipetting, or automatically distributing by using the churn splitter. The various mixing methods and the lack of a well defined procedure can cause errors in recover. This study analyzes the deviations among mixing processes and establishes the best mixing process for the TSS experiment.

The TSS standard method was performed based on Standard Methods for Examination of Water and Wastewater. Silicon beads and embedded sediments were used in the experiments. Several mixing processes were performed. Pour and pipette subsamples after shaking or after stirring. Pipette subsamples after stirring in the container with baffles or the square shape of the container. Pipette after stirring by the gang-mixer.

Pouring subsamples is less precise than pipetting either after shaking or stirring. It is also more difficult to obtain accurate volumes when pouring. Stirring yields more precise results than shaking. With pipetting subsamples and 250 RPM mixing speed, experiments using gang-mixer show 74% recovery rate of the particles smaller than 90 mm but only 8% recovery rate of the particles larger than 125 mm. Larger particles can be observed at the bottom of the sample collection beaker. Simply increasing mixing speed produces a large vortex when prevents mixing. Beakers with baffles and square container were utilized to eliminate the vortex but resulted in dead zones that trapped suspended solids. The experiments show that pouring has poor recovery rate of the real concentration. Shaking samples may result in partial mixing and uncertain particle concentration of the subsamples. Beakers with baffles and square containers are unsuitable for the mixing. Particles smaller than 250 mm have more than 95% recovery rate and 72.4% recovery rate for those larger than 250 mm at 700 RPM mixing speed. In sum, using stirrers, stirring at the mixing speed of 700 RPM or higher in a regular beaker, and using pipettes transferring subsamples gives the best recovery rate.

Materials Properties of Polymer Blends of Poly(3,4-ethlenedioxythiophene)/poly(styrenesulfonate) (PEDOT:PSS) and Polyvinyl Alcohol (PVA)

論文發表人: 陳常修 (加州大學爾灣校區/Department of Chemical Engineering & Materials Science)

 

http://www.mrs.org/s_mrs/sec.asp?CID=13576&DID=207893&SID=1

 

混合導電高分子化合物可以建立微機電系統的機械結構,它不只具有良好的電性,同時也具有強韌的機械特性.它大幅的被應用於生醫領域及光電領域.PEDOT:PSS化合物是一個低電阻的導電高分子,而PVA化合物則是水溶性的混合添加劑,用來強化元件的結構.混合溶液利用旋轉塗佈的方式形成導電高分子薄膜.緊接著用四點探針的方式來測量交流電及直流電的電性,如導電強度.不同的導電強度可有不同的應用.機械強度方面,像是楊式係數或是拉申強度,可經由量測元件的共振強度而計算得知.高分子的楊式係數大約是1-5GPa.如此小的楊式係數可以進一步的縮小微機電元件或是其他方面的尺寸.導電高分子薄膜的導電強度隨著導電高分子化合物PEDOT:PSS增加而增加;PVA化合物則影響其機械強度從易脆到易延展的.此外,導電增強劑NMP化合物也混入此導電高分子系統讓此導電高分子薄膜導電性增加一百倍

 

The structure material of microelectromechanical systems (MEMS) has been built with two polymer blends Poly(3,4-ethlenedioxythiophene)/poly(styrenesulfonate) (PEDOT:PSS) is a high conductivity polymer. And a water soluble non-conductive synthetic polymer, polyvinyl Alcohol (PVA), leads to increase tensile strength, durability and flexibility. Mixtures were prepared and spin coated to form thin films. The AC and DC electrical properties of the thin films are studied using the four point probe method. Studies of electrical properties will lead materials to different applications. And the mechanical properties, such as Young's Modulus and tensile strength of the thin films might be relative with resonance frequency. Young's Modulus of polymer blends are anticipated around 1-5GPa. These lower Young's Modulus polymers than metals can minimize the dimension of MEMS devices and other applications. The film conductivities increased proportional to the increase in conducting polymer PEDOT:PSS content. And thin films became ductile from brittle with increasing PVA content. In addition, (N-Methyl-2-pyrrolidinone), a conductivity enhancer, was introduced and resulted in an increase of the conductivity of the polymer blends with the order of 100

Identification and characterization of Waitea circinata var. circinata, an emerging pathogen of turfgrass.

論文發表人:陳其敏(加州大學河濱校區/Plant Pathology and Microbiology Department)

 

http://www.ag.ndsu.nodak.edu/aginfo/barleypath/rhizoc/meeting.htm

 

Waitea circinata var. circinata (Wcc) 於2003年被發現在美國東部，美西以及中西部的數十個高爾夫球場引起嚴重草坪病害brown ring patch◦ 根據本研究Wcc是Rhizoctonia的有性世代之一，許多的Rhizoctonia spp能感染禾本科葉部或根部造成植株死亡◦ 早熟禾屬的annual bluegrass (Poa annua)以及rough bluegrass (Poa trivialis)已被報導可被Wcc感染，這兩種草種在美國被廣泛的應用於草坪植被，尤其是高爾夫球場◦ 在這份研究中，藉由分子生物技術 (rDNA ITS序列和RFLP [Restriction fragment length polymorphism])以及形態鑑定，確認由全美各地蒐集的42個病害樣本均被Wcc感染，同時這些樣本的rDNA ITS序列顯示出高度的歧異，指出此病原菌並非如預期的是近期傳入，實際上可能已經存在美國境內很長一段時間◦  rDNA ITS序列經過解析以及基因選殖，根據五個核酸位置的核酸變異 (三個heterozygosities 以及兩個indels) ，這四十二株樣本可被歸類為十八種變異種◦然而，這十八個變異種與其地理分布並無任何關連◦本研究同時證實雖然菌落形態鑑定以及分子鑑定有不同程度的變異，但變異程度不大，因此上述兩項鑑定方法仍然足以做為病害鑑定之依據◦

 

Brown ring patch, caused by Waitea circinata var. circinata (Wcc), is an emergent disease of annual bluegrass (Poa annua) and rough bluegrass (Poa trivialis) in the U.S. Since 2003, it has been reported in multiple locations in the western, mid-western and northeastern U.S. The objective of this study was to confirm the identity of pathogen from 42 isolates collected from these diverse locations using colony morphology, and RFLP and sequence analyses of the rDNA-ITS region. The colony morphology of collected isolates was distinct from other anamorphs of Waitea circinata (Rhizoctonia oryzae and R. zeae), but bulbil color and morphology were variable on PDA with 2-mm to 5-mm diameter bulbils ranging from dark brown to orange to white being produced after 28 days in culture. RFLP analysis of ITS1F-ITS4 amplified regions followed by digestion with HapII produced RFLP unique patterns not previously reported from studies with Wcc in Japan and California. Additional sequencing of multiple clones of the amplified ITS region for the 42 isolates, revealed heterozygosity, the presence of poly-nucleotide indels and other sequence variation between isolates. A total of 18 ITS haplotypes were found and there was no association of the haplotypes with geographic distribution. Results from this study indicate that colony morphology and rDNA-RFLP analysis can be more variable than previously reported, and that this variation should be taken into account for identification and diagnosis. The sequence diversity of the amplified ITS-region, the presence of heterozygous sites and indels, provides some measure of genetic diversity of Wcc in the U.S. and suggest that the pathogen has been present in the U.S. for a time and is not a recent introduction to turfgrass. Further studies using additional markers or methods are needed to more adequately address this aspect of the population biology of Wcc.

Quantum dot-based nuclease-resistant molecular beacons for visualizing the Coxsackievirus replication in living cells via TAT peptide delivery

論文發表人: 葉曉芸(加州大學河濱分校化學工程學研究所)
http://portal.acs.org/portal/acs/corg/content?_nfpb=true&_pageLabel=PP_TRANSITIONMAIN&node_id=859&use_sec=false&sec_url_var=region1

 

分子信標技術是基於螢光共振能量轉移現象和鹼基互補配對原則建立，於顯微鏡下直接觀測與新合成病毒RNA結合而產生的螢光，方法簡單且不需探針分離的步驟。進行活體細胞即時研究時，細胞酶會導致分子信標水解進而破壞其結構,有機螢光分子也易受光降解的影響。我們發展抗核酸酶分子信標結合無機螢光共振能量轉移對 - 量子點與金奈米粒子。TAT胺基酸於15分鐘內能成功將信標組送入活體細胞裡。BGMK細胞以10倍病毒連續稀釋感染,於顯微鏡下即時監控螢光的密度並觀察完整的病毒繁殖週期。病毒劑量與螢光細胞的數量呈正相關。與傳統的48小時病毒斑檢驗法比較,本研究提供一更為迅速且同等準確的檢驗方法。

 

Molecular beacons (MB), which produce fluorescence upon target binding, provide a simple and separation-free detection scheme. By directly visualizing the fluorescent hybrids with newly synthesized viral RNA, MB can be used to provide a rapid and sensitive detection of infectious viruses. For real-time studies in living cells, however, the durability of MBs is affected due to nuclease degradation and the rapid photodegradation of the organic fluorophore. In this study, we developed nuclease-resistant MBs composed of CdSe/ZnS quantum dots as donors and gold nanoparticles as quenchers for the in vivo detection of infectious viruses. For intracellular delivery, a hexahistidine-appended cell-penetrating TAT peptide was self-assembled onto the quantum dot surface via metal-affinity interactions. Presence of the TAT peptide allowed nearly 100% intracellular delivery within 15 min. Confluent buffalo green monkey kidney (BGMK) monolayers were infected with virus dilutions and the fluorescence intensity was monitored in real time. Fluorescence microscope was used to directly visualize infected cells and to subsequently follow virus spread among cells in vivo. The number of fluorescent cells increased in a dose-responsive manner and enabled the direct quantification of infectious viral doses. Using the 2-h infection window, the validation of the MB-based fluorescence assay for viral quantification was demonstrated by comparing with the traditional 48-h plaque assay.

 

Decision Fusion in Sensor Networks for Spectrum Sensing based on Likelihood Ratio Tests

 論文發表人：鍾偉和（加州大學洛杉磯分校電機工程研究所博士班）

 

http://spie.org/

 

近年來由一定數量的偵測器所形成之偵測器網路已有廣泛的應用，其中一個重要的應用就是經由偵測器的共同決策來增加訊號偵測的準確度。在感知無線電的應用中，訊號偵測的準確度相當重要，在這篇論文中，我們研究利用偵測器網路共同決策來作為感知無線電頻譜偵測的方法，我們的研究架構是利用可能性比率的方式。在可能性比率的架構中，每一個偵測器作各自獨立的偵測，這些獨立的偵測結果再傳送到中央決策點進行最後決策，經由融合多數的獨立決策的方式，最後決策將會有較高的準確度。我們提出一個偵測機率低標的準則來作為傳統尼曼皮爾森準則之外的一個決策準則，在偵測機率低標準則裡，偵測器維持偵測機率在一定水準之上，追求最小的誤警報率。在感知無線電中，偵測機率低標準則可以限制頻譜衝突的機率在一定水準之下。在這篇論文中，我們也提供演算法可以計算出在決策中心的決策規則、偵測率、及誤警報率。在無線電訊號的偵測中，無線通道常常影響偵測的準確度，我們把無線通道的特性考慮進演算法中，經由考慮無線通道的特性，訊號偵測的準確度可以增加。我們並在文中提供模擬的結果來驗證所提出的演算法。

 

Sensor networks have been shown to be useful in diverse applications. One of the important applications is the collaborative detection based on multiple sensors to increase the detection performance. To exploit the spectrum vacancies in cognitive radios, we consider the collaborative spectrum sensing by sensor networks in the likelihood ratio test (LRT) frameworks. In the LRT, the sensors make individual decisions. These individual decisions are then transmitted to the fusion center to make the final decision, which provides better detection accuracy than the individual sensor decisions. We provide the lowered-bounded probability of detection (LBPD) criterion as an alternative criterion to the conventional Neyman-Pearson (NP) criterion. In the LBPD criterion, the detector pursues the minimization of the probability of false alarm while maintaining the probability of detection above the pre-defined value. In cognitive radios, the LBPD criterion limits the probabilities of channel conflicts to the primary users. Under the NP and LBPD criteria, we provide explicit algorithms to solve the LRT fusion rules, the probability of false alarm, and the probability of detection for the fusion center. The fusion rules generated by the algorithms are optimal under the specified criteria. In the spectrum sensing, the fading channels influence the detection accuracies. We investigate the single-sensor detection and collaborative detections of multiple sensors under various fading channels, and derive testing statistics of the LRT with known fading statistics.

Does Demographic Change Matter for Growth?

 

論文發表人: 廖珮如 (加州大學洛杉磯分校經濟學系博士班)

 

http://www3.grips.ac.jp/~econseminar/GRIPSconference2008.html

 

人口變遷對經濟成長有影響嗎? 實證文獻提出許多證據支持人口變遷對經濟成長的正面影響, 但理論文獻卻付之闕如。本文利用疊代模型解釋並估計人口變遷對經濟成長的影響。與文獻不同的是, 本文的疊代模型將繁殖率(fertility)內生化, 並考慮人口變遷影響經濟成長會透過三個途徑: 人口年齡結構的變化, 物質資本累積, 與人力資本累積。利用本文建構的模型, 我們試圖回答兩個問題: 人口變遷對經濟成長的貢獻有多少? 在本文所討論的三個途徑中, 哪一途徑最為重要? 我們選擇台灣作為數量分析的一個例子。分析結果顯示, 在1970-2004年之間, 人口變遷每年大約可產生1.3%的人均國內生產毛額。此外, 我們也發現生產技術進步和人口變遷之間存在著重要的交互作用。當人口變遷的同時,若生產技術轉變成較為技術密集的生產方式, 它們之間的交互作用會促進更多的人力資本累積。最後, 當一國的生產技術為技術密集時,在三個途徑中,人力資本比人口結構變化更為重要。

 

How important is the demographic transition for economic growth? To answer this question, this paper constructs a general equilibrium overlapping generations model with endogenous fertility in which demographic change affects growth through three channels: changes in the age composition of the population, the accumulation of physical capital, and the accumulation of human capital. In the case of Taiwan, our quantitative analysis suggests that during the period 1970-2004, demographic change contributed growth in GDP per capita by about 1.3 percent per year. We also find important interactions between demographic change and technological progress. When production technologies become more skill intensive as the demographic transition occurs, the interaction promotes human-capital accumulation. In this case, the human-capital channel is more important than changes in the dependency ratio.

 

Art, Politics & Climate in the Middle Years of the Northern Song

 

 

論文發表人: 彭慧萍(加州大學聖塔芭芭拉校區藝術史與建築史系博士班)

 

http://www.sis.zju.edu.cn/sis/sisht/Article/ShowArticle.asp?ArticleID=4497

 

本文藉由北京故宮藏北宋徽宗畫《雪江歸棹圖》暨卸任宰相蔡京1110年題跋，折射徽宗宮廷不尋常的政治氛圍。在徽宗朝新、舊兩黨激烈的政治角逐戰中，新黨蔡京暨其政敵張商英利用徽宗的迷信，利用雪景圖、嘉禾圖等藝術品，及截然對立的政治語彙，將星變、雪災等自然災變，解讀為祥瑞/災異、天祐/天譴等極端闡釋，以攻擊敵黨。1109年罷相的蔡京於1110年題跋《雪江》時正值其個人的"政治冬天"，書法作為直觀的視覺刺激，是處於劣勢的蔡京賴以駁擊的最佳武器。藉由題跋，蔡京投射天災人禍下孤獨的自我意象，及對宇宙天文變幻無常的喟嘆，冀望喚醒徽宗的同情，沖淡政敵依附天變、雪旱災的無情攻擊。而徽宗作為一位文人皇帝，于公於私均扮演周旋雙黨的複雜角色。徽宗于公對蔡京罷相降官，於私命蔡京觀畫題跋，彌縫與蔡的私人交誼。而徽宗對"雪江歸棹圖"的五字簽題，亦是其對蔡京即將遭竄，然終將"歸朝"的無形暗示。兩年之後蔡京還朝，其政治春天終於來臨。徽宗贈給蔡京另幅氣勢壯闊的春景圖(北京故宮藏千里江山圖)，其中徽宗贈言暨蔡京題跋，正與《雪江》前後呼應。據此，藉由雪景圖、春景圖，可看出書畫藝術如何在徽宗宮廷中，作為政治戰爭的溝通利器。

 

 

Painting and other arts were strongly embedded in the unique culture of the court of the late Northern Song emperor Huizong (r. 1100-1125). While many scholars have examined the emperor's artistic patronage, none have recognized the crucial role that climate and the 'reading' of nature may have played in court politics. The scroll painting "Returning Boats on a Snowy River," with its colophon by Huizong's colourful Prime Minister Cai Jing (1046-1126), will be used as a springboard for consideration of a number of issues. For example, painting and calligraphy were used as potent weapons in the struggle for power in the court of an increasingly superstitious emperor. Additionally, art also played a central role in the binary game of 'auspicious' and 'inauspicious' reporting of natural events (climate, comets, sunspots, snowfalls, droughts) by rival political factions. Cai Jing was a central figure in these practices and his career provides us with an exceptionally rich case study for the relationship between artistic patronage and court politics. The popularity of snow-themed paintings during this era will be related to a significant climatic event which occurred during the closing years of Huizong's reign: the Little Ice Age. Such conventional seasonal paintings with 'auspicious' themes were produced in great numbers as the Song Dynasty dissolved, helping create an idealized world for the increasingly isolated Huizong, whose empire was crumbling under the social and economic upheaval created by the agricultural disasters of the Little Ice Age. Indeed, the subject parallels some current fears about global warming and catastrophic climate change. Complex new layers of meanings for art and climate are articulated in this study, which draws on various types of Song primary texts not previously considered by art historians.