1,720,962 research outputs found
Metamorphoses — Multiple Self-Portraits： Creation Description by Lin Tzu-Chiao
No full text[[abstract]]This dissertation begins with an inner reflection on self as subject. Through personal observation and dialogue with the psyche, the writer examined his own consciousness and sub-consciousness, and from this process, has developed a series of transfigured human forms. Meanwhile, the writer has used these creatures as a starter to explore a new kind of multiple self-portraits of modern times.
Taking Carl Jung’s concepts of “persona”and “ombre”(shadow) as main points of reference, supported with Jacques Lacan’s psychoanalytical concepts of “mirror stage,” the writer also offered his personal experience and creating background as materials to be related to or analyzed.
These multiple self-portraits were done with simplified, exaggerated, and grotesque expressions. The figures have cartoon-styled heads and realistically-sketched bodies. With combination of several media (like ink, glue colors, charcoal pencils…) the writer/painter has created visual images of mixed styles.
Using “body”and “human shapes”as a main way to creatively express himself, the writer/painter probed into his memories psychoanalytically. It was in this interchange between conscious and subconscious phases, between reality and dreams, between outpouring of creative energy and self-reflection that “transfigured shapes”stood out as a distinctive feature of his paintings.A human form appeared on a painting as a result/embodiment of the writer/painter’s inner process, and then another inner process began as a result of his interaction with this painted human form. That is to say, the writer/painter’s unique “feelings and understanding” of the moment triggered the formation of a particular“shape”, and this certain “shape” in turn induced another round of “feelings and understanding”. Thus is born the indefinite and ever-evolving “multiple self-portraits”.
Study of Fault Location Algorithms for Two-Terminal/ Three-Terminal Multisection Compound Transmission Lines Based on Synchronized Phasor Measurements
No full text本論文針對諸多地下電纜與架空線路混合、多種線徑架空線路，以及多種線徑地下電纜線路所組成之雙端點與三端點多區段複合線徑型輸電線架構提出了以同步相量量測為基礎的故障定位演算法，其中同步相量量測值來源分別為以全球衛星定位系統(Global Positioning System, GPS)為基礎之相量量測單元(Phasor Measurement Units, PMUs)、內建PMUs之數位電驛資料，以及經由電驛量測訊號之非同步校準演算法等。本論文之研究目的首重於解決目前在文獻中各種所被提出的方法皆尚且無法完全處理此類型多區段複合線徑線路架構的故障定位問題。
本論文的研究理論是基於單一線徑兩端輸電線路故障定位技術進一步延伸到兩端及三端多區段複合輸電線路的故障定位演算法設計。利用本論文所提出的演算法，包含故障分支線段選擇器、故障區段選擇器，以及故障定位器之搭配組合，則不僅對於兩端點及三端點複合輸電線路可輕易地識別出內外部故障以及故障區段，更有能力進一步地定位出不論是發生於架空線路或者地下電纜線路事故的正確故障位置。
本論文所提出之故障定位方法擁有嚴謹的理論基礎，且由於不會受到故障型態、電源阻抗，以及負載大小等影響，再加上不需進行疊代計算的優點，因此本方法能夠直接地、簡單地求出故障位置的精確解，並且有效地降低了數學運算的複雜度。不論是模擬驗證還是實際輸電線路事故測試，皆一致地證明了本演算法的效能。所提出的演算法已經自西元2008年起實際運用在台灣345 kV以及161 kV的輸電系統上面。相較於建置在輸電系統上數位保護電驛本身擁有的故障定位功能，到目前為止，本演算法展現出較數位電驛更精確故障定位成果與更強健的性能。In this dissertation, an innovative fault location algorithm for two- and three-terminal multisection compound transmission lines using synchronized phasor measurements (synchrophasors) provided by Global Positioning System (GPS) based Phasor Measurement Units (PMUs) or digital relays with embedded PMUs or by pre-fault and fault-on relay data synchronization algorithms, is proposed. This dissertation addresses the fault location issues for non-homogeneous line models, which cannot be solved exactly by the existing fault location methods proposed in open literature yet. The proposed algorithm is extended from a two-terminal fault location method for homogeneous lines to the algorithms for two- and three-terminal multisection compound lines which combine overhead lines with underground power cables. Specifically, faulty branch selector, faulty section selector, and fault locator for two- and three-terminal multisection compound lines are proposed, which can not only distinguish an internal fault of a compounded line from an external fault but also have the ability to locate a fault on an overhead line or an underground cable as well.
The proposed algorithm has a solid theoretical foundation and is direct and simple in terms of computational complexity since neither fault type selections nor iterative operations are required. Both extensive simulations and field evaluations have been presented to demonstrate the effectiveness of the proposed algorithm. The proposed algorithm has already been implemented in the Taiwan power system since the year 2008. So far the algorithm yields excellent performance and robustness compared to fault location methods of installed digital relays in Taiwan
Blind Parametric Estimation in OFDM Systems
No full text在這篇博士論文中，我們致力於研究正交分頻多工系統之參數盲蔽估測。內容主要分兩個部分。在第一個部分，我們探討了載波頻率偏移和實虛部非協調的問題。在第二個部分，我們研究了雙向中繼站傳輸網路的通道響應之估測。 載波頻率偏移和實虛部非協調是低成本通訊架構中常見的問題。載波頻率偏移會嚴重地破壞正交分頻多工系統當中的正交性，造成錯誤率大幅提升。而實虛部非協調的存在也會影響到載波頻率偏移的估測。因此在論文的第一部分，我們會探討有關載波頻率偏移和實虛部非協調的盲蔽估測問題。 首先，我們提出了一個利用循環前綴的演算法來盲蔽估測正交分頻多工系統中的載波頻率偏移和實虛部非協調問題。類似於其他循環前綴的方法，我們的方法複雜度也很低。在載波頻率偏移估測的部分，我們的方法能有效地對抗時間不同步造成的影響。此外我們還算出了理論上的錯誤率及克雷曼-勞氏邊界。在實虛部非協調估測的部分，我們的方法不需要知道真實的載波頻率偏移量。因此結合上述兩種方法，我們可以解決載波頻率偏移和實虛部非協調同時存在的問題。首先我們先估測被載波頻率偏移影響的實虛部非協調參數。接著將實虛部非協調作適當的補償。最後我們可以估測補償實虛部非協調影響後的載波頻率偏移量。 另一種估測載波頻率偏移和實虛部非協調參數的方法是利用振幅相等的星座圖。其中有個複雜度很低且很有效率的作法叫做頻率分析。頻率分析法相當簡單，但是在許多通訊系統中會有虛擬載波的存在，而虛擬載波會造成頻率分析法的錯誤率大幅提升。因此我們根據頻率分析法的理論基礎來探討虛擬載波造成的影響並提出了適當的修正。並且利用弦波近似和拋物線近似來降低這方法的複雜度。 在過去十年間，中繼站傳輸網路的研究逐漸盛行了起來。其中雙向中繼站傳輸網路因為傳輸率夠高而受到較大的關注。在這篇論文的第二部分，我們研究了放大轉發雙向中繼站傳輸網路的通道響應之估測。並將正交分頻多工系統應用於此類網路。該網路中的通道以兩段式步驟來做估測。首先我們利用能量降低的做法估測自我干擾的通道響應。其次利用子空間的作法估測真正發射端及接收端之間的通道響應。此外我們還算出了理論上的錯誤率及近似的克雷曼-勞氏邊界。In this dissertation, we study blind algorithms for parametric estimation in orthogonal frequency division multiplexing (OFDM) systems. Our works include two parts. In the first part, we discuss the problem of carrier frequency offset (CFO) and in-phase and quadrature-phase (I/Q) imbalance in OFDM systems. In the second part, we study the identification of channels for OFDM-based amplify-and-forward two-way relay network (AF-TWRN) systems. CFO and I/Q imbalance are two common front-end imperfections in low-cost communication devices. It is known that CFO is a crucial problem in OFDM systems. It can destroy the orthogonality between subcarriers and cause significant degradation in system performance. Moreover, the existence of the I/Q imbalance usually reduces the accuracy of CFO estimation. In the first part of the thesis, we study blind estimations for CFO and I/Q imbalance. Firstly, we propose algorithms based on cyclic prefix (CP) for blind estimations of CFO and I/Q imbalance in OFDM transmission over multipath channels. Like other CP-based methods, the proposed methods enjoy low complexity, and closed form formulas are derived. For CFO estimator, the proposed method is very robust to the symbol timing synchronization error. In addition, we also carry out the theoretical mean square error (MSE) analysis and derive the Cramer-Rao bound (CRB). For I/Q parameter estimator, the proposed method does not need to know the CFO value. Hence, by combining these two estimators, we can solve the joint estimation problem of CFO and I/Q imbalance in two stages. First the I/Q parameter is blindly estimated in the presence of CFO and then the CFO can be blindly estimated after compensating the I/Q effect. Another popular technique for blind estimation of CFO and I/Q imbalance is by exploiting constant modulus (CM) constellations. An effective low cost method, called frequency analysis (FA) method was proposed. The FA methods are simple and have closed form solutions. However, in many existing standards for communications, virtual carriers (VC) are introduced for the purpose of system design. When there are VCs, the FA methods degrade significantly. We propose the algorithms based on FA for blind estimation of CFO in the presence of VCs. The cost functions can be well approximated by sinusoidal and parabolic functions and thus the closed form formulas can still be exploited. In the last decade, research on wireless relay networks became popular. In particular, the TWRN has drawn a lot of attention because its overall communication rate is approximately twice of that achieved in the one-way relay network (OWRN). In the second part of the thesis, we propose a blind channel estimation algorithm for AF-TWRN. The OFDM modulation is adopted for frequency selective channel. The proposed method can be also applied to zero-padded OFDM systems. The two cascaded channels are estimated in two steps. First the cascaded channel causing the self-interference is estimated using a proposed power reduction method. Then the other cascaded channel from source to destination is estimated by subspace method. Closed form formulas for channel estimates are derived. In addition, we also carry out the theoretical MSE analysis and derive the approximated CRBs
A Study on the Food Security and Food Supply Planning in the Emergency Period in Taiwan
No full text隨著世界糧食需求與供給波動增加，糧食價格於2002年起呈現上升之趨勢，並於2006至2008年間巨幅上漲，引發世界各國對糧食安全相關議題的重視；我國屬於糧食淨進口國，在此糧食價格與供給量波動的背景下，可能因糧食出口國採取出口干預策略，而面臨糧食進口受阻的非常時期。本研究整理分析糧食安全風險與因應措施，以及非常時期糧食安全因應措施的相關文獻，並針對不同經濟發展程度和農業資源稟賦類型國家的糧食安全問題與因應措施進行分析。由於非常時期國家穩定供給糧食為我國重要糧食安全議題，故參考林國慶（2011）建構之非常時期糧食供需模型，同時分別對2020年三項影響糧食供需的重要變數（我國總耕地面積、各品項作物每公頃期作種植面積平均產量、我國總人口數）進行樂觀與悲觀情境設定，並將三變數之樂觀與悲觀情境組合成八種不同情境並進行實證模擬。本研究之實證結果如下：（1）若我國於2020年發生無法進口糧食之非常時期，則在本研究設定之八種情境下，國人皆能取得平均每人每日2,000大卡之最低熱量需求，以及12％之最低蛋白質占總熱量營養需求；（2）當我國面臨非常時期時，為供給國人維生與營養所需之糧食，糧食供給組合相對於平常時期將會顯著改變；（3）比較我國與日本2020年非常時期糧食供給組合模擬結果，我國任一情境糧食供給組合之平均每人每日熱量供給或PFC比例，都較日本非常時期之消費型態為佳。本研究根據實證結果提出以下政策建議：（1）本研究採用之模型以耕地為基礎，因此欲確保此模擬結果，平常時期應有效維護耕地數量與品質；（2）為確保非常時期我國耕地之生產力，政府應於休耕地進行生產試驗，以了解耕地休耕對平均產量的影響，同時建議耕地不應長期休耕、棄耕或廢耕，並維持我國耕地處於妥適的經營狀況與生產力，確保多數耕地能處於隨時皆能投入生產的狀況；（3）本研究模型假設非常時期水資源取得無虞，但欲確保此模擬結果，平常時期應妥善維護水資源及灌溉設施；（4）本研究假設我國面臨非常時期時，國內糧食平均產量不會受到氣候變遷或極端氣候的影響，因此欲確保此模擬結果，政府應針對非常時期可能的自然災害，以及自然災害與糧食供給關係進行更深入的評估。With the increase of fluctuation in world food demand and supply, the price of food has gone up since 2002, and soared between 2006 and 2008. This has aroused the world wide concerns about the food security issue. With the fluctuation of food price and quantity, food export countries may take export intervention strategies. Therefore, a net food import nation like Taiwan may face a crisis of unable to import the food. This study analyzes literature on food security risks, food security risk management and emergency period food security risk management. Then the study analyzes the food security risks and food security risks management in different types of countries, which are classified according to economic status and agricultural endownment. Since stable food supply in an emergency period is a major concern to Taiwan, the study refers to Lin Kuo-Ching（2011）emergency food supply and demand model, and sets optimistic and pessimistic scenarios in 2020, focusing on the three important variables, including total farm land, per hectare planed area output of each agricultural products and total population. The study composes optimistic and pessimistic scenarios of the three variables into eight different scenarios and conducts the empirical simulation. The results of this empirical simulation are summarized as follows: (1) If an emergency occurred in 2020, all people could obtain the minimum calorie intake (2,000 Kcal) and protein ratio (12％), under the eight circumstances designed in the study. (2) In order to provide food for domestic people to survive and achieve nutrient requirements in an emergency period, the diet composition will be diffirent significantly. (3) Compared with the consumption pattern of Japan during the special period, the consumption pattern in Taiwan is better, including the calories and nutrients basis. According to the simulation result, the policy recommendations made are summarized as follows: (1) Since the model used in this study is based on the farm land, ensuring quantity and quality of the farm land is essential to achieve the the result. (2) In order to understand the relationship between set aside farm land and its productivity, the government should make experiments on set aside farm land to ensure the productivity of the farm land in an emergency. It also suggests that not to set a farm land aside for a long period of time, neither abandon nor discard. The farm land should be maintained in proper management and productivity, so that it can be always ready to put into production. (3) The model used in the study assumes that water resource is certainly acquirable, therefor maintaining water resource and irrigation facility in normal period is indispensable. (4) Since assumptions of the model is domestic productivity will not be affected by climate change or extreme weather in an emergency period, the government should do more detail assessment of natural disaster in an emergency and the relationship between natural disaster and food supply in an emergency to assure the simulation result can be achieved
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Synkronisering på PSK Over-the-Air Beräkning
No full textSynchronization issues pose significant challenges for the implementation of Over-the-Air Computation (AirComp). Despite its importance and broad applications, practical implementations of AirComp remain underexplored. A comprehensive understanding of synchronization problems in AirComp is essential for its successful deployment. This thesis addresses the synchronization challenges in AirComp using mathematical modeling and computer simulations with Binary Phase Shift Keying (BPSK) modulation. Additionally, we develop and implement a transceiver chain using Software-Defined Radio (SDR) technology, involving two edge devices and one edge server, to validate our mathematical model and simulations. The results from SDR testing closely match our simulation and mathematical outcomes, demonstrating that the quality of the Radio Frequency Front-End (RFFE) significantly affects signal interference and synchronization quality.Synkroniseringsproblem utgör betydande utmaningar för implementeringen av Over-the-Air Computation (AirComp). Trots dess betydelse och breda tillämpningar är praktiska implementeringar av AirComp fortfarande underut- forskade. En omfattande förståelse av synkroniseringsproblem i AirComp är avgörande för dess framgångsrika implementering. Denna avhandling adresserar synkroniseringsutmaningarna i AirComp genom matematisk modellering och datorsimuleringar med binär fasförskjut- ningsnyckling (BPSK) modulation. Dessutom utvecklar och implementerar vi en sändar-mottagarkedja med hjälp av mjukvarudefinierad radio (SDR)- teknik, som involverar två kant-enheter och en kant-server, för att validera vår matematiska modell och våra simuleringar. Resultaten från SDR-testningen överensstämmer väl med våra simulerings- och matematiska resultat, vilket visar att kvaliteten på Radiofrekvensfrontände (RFFE) påverkar signalinterferens och synkroniseringskvalitet avsevärt
Synkronisering på PSK Over-the-Air Beräkning
No full textSynchronization issues pose significant challenges for the implementation of Over-the-Air Computation (AirComp). Despite its importance and broad applications, practical implementations of AirComp remain underexplored. A comprehensive understanding of synchronization problems in AirComp is essential for its successful deployment. This thesis addresses the synchronization challenges in AirComp using mathematical modeling and computer simulations with Binary Phase Shift Keying (BPSK) modulation. Additionally, we develop and implement a transceiver chain using Software-Defined Radio (SDR) technology, involving two edge devices and one edge server, to validate our mathematical model and simulations. The results from SDR testing closely match our simulation and mathematical outcomes, demonstrating that the quality of the Radio Frequency Front-End (RFFE) significantly affects signal interference and synchronization quality.Synkroniseringsproblem utgör betydande utmaningar för implementeringen av Over-the-Air Computation (AirComp). Trots dess betydelse och breda tillämpningar är praktiska implementeringar av AirComp fortfarande underut- forskade. En omfattande förståelse av synkroniseringsproblem i AirComp är avgörande för dess framgångsrika implementering. Denna avhandling adresserar synkroniseringsutmaningarna i AirComp genom matematisk modellering och datorsimuleringar med binär fasförskjut- ningsnyckling (BPSK) modulation. Dessutom utvecklar och implementerar vi en sändar-mottagarkedja med hjälp av mjukvarudefinierad radio (SDR)- teknik, som involverar två kant-enheter och en kant-server, för att validera vår matematiska modell och våra simuleringar. Resultaten från SDR-testningen överensstämmer väl med våra simulerings- och matematiska resultat, vilket visar att kvaliteten på Radiofrekvensfrontände (RFFE) påverkar signalinterferens och synkroniseringskvalitet avsevärt
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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