1,721,044 research outputs found
A Study reffered to the Influence of Heterogeneities in Porous Media on Hydraulic Conductivity and Soil Hydraulic Property
No full text地下水在水資源系統中，占極重要的一環。隨著地下水使用頻率逐年升高，近幾年來，相關模式之研究亦蓬勃發展。而對使用者來說，模式中地下水參數之設定是否合宜，便成為模擬結果成敗之重要關鍵；尤其在現地中，地表下之土層狀況並非均質，異質物於土壤空間分佈及土壤中所含有之異質物之多寡，對地下水流或污染之傳輸影響甚巨，為了能徹底了解異質物對地表下傳輸行為之影響，故本研究遵循達西定律，在不同水力梯度下，分別進行土壤中異質物含量及隨空間分佈不同之定水頭砂箱實驗，以求出土壤之水力傳導係數，並與三維地下水模擬模式VSAFT2(Variably Saturated Flow and Transport utilizing the Modified Method of Characteristics, in 2D)之模擬結果進行比較分析，此外，亦透過模式中模擬水力特性曲線之V.G.公式，來探討非飽和之水力特性曲線。本研究結果顯示：異質物含量增加及排列愈複雜時，其平均水力傳導數會降低，而模式模擬水力傳導係數與實驗之結果比較，兩者最大誤差控制在小數點以下二位，說明該模式在模擬含異質物時之地下水流動具有相當的準確性。The ground water plays an important role in water resources system. The models of ground water are presented more and more by the increasing frequency of using ground water resources. How to set the parameters correctly becomes a key of a successful simulation for users. Especially for In-situ test, the soil characteristics in the subsurface are not homogeneous; the heterogeneities have an enormous influence on the transport of ground water flow or chemical. For this reason, we solve this problem by a constant head sand-box experiment at different hydraulic gradient with heterogeneities in porous media. Then we compare the result with the VSAFT2 model and use the V.G. formula to simulate the hydraulic properties curves. The results reveal that when the heterogeneities increase or the distribution of porous media becomes complicated, the hydraulic conductivity will decreases and the hydraulic properties curves will change. Finally, it can be concluded that the VSAFT2 model is reliable by comparing the results of experiment and model simulation.審定書....................................................I謝.....................................................II文摘要................................................III文摘要.................................................IV錄......................................................V目錄..................................................VII目錄....................................................X一章 導論............................................1.1研究緣起...............................................1.2研究目的...............................................2.3研究流程及步驟.........................................2.4文章架構...............................................3二章 文獻回顧........................................5.1實驗及水力傳導係數之相關研究...........................5.2 VSAFT2模式之相關研究..................................7三章 砂箱模型試驗.......................................9.1砂箱模型試驗...........................................9.1.1定水頭試驗...........................................9.1.2達西定律............................................10.1.3試驗校正-溫度、雷諾數影響因子.......................12.2試驗準備工作..........................................16.2.1土壤基本性質及試驗..................................16.2.2砂箱模型介紹........................................19.2.3透水石..............................................20.2.4水管、量筒及水箱模型................................22.2.5土樣填放及異質物埋設................................24.3試驗流程與步驟........................................26四章 模式理論及應用....................................30.1 VSAFT2模式理論.......................................30.2 VSAFT2模式功能.......................................33.3 VSAFT2模式應用.......................................35 4.3.1VSAFT2模擬砂箱試驗...............................35 4.3.2VSAFT2模擬水力特性曲線...........................38五章 實驗與模式結果....................................41.1土壤基本性質試驗......................................41.2砂箱試驗與飽和模式模擬結果............................43.2.1砂箱試驗結果........................................43.2.2VSAFT2模式模擬結果..................................48.3雷諾數之檢覈..........................................51.4實驗與模式模擬之比較..................................52.5水力特性曲線模擬結果..................................57.5.1均質土壤中且無異質物模擬結果........................57.5.2異質物排列均勻含量10%及20%..........................59.5.3異質物隨機排列含量10%及20%..........................63六章 結論與建議........................................69.1結論..................................................69.2建議..................................................70考文獻.................................................7
Biophysical Cues on Modulation of Myoblast Differentiation Using Hydrostatic Pressure and Elastomeric Matrix of Tunable Stiffness
No full text細胞在體內存活、更新增生、和分化，是需要一個複雜且動態調控生長因子、細胞外基質、和生物物理力學刺激整合的微環境。因此本實驗目的欲探討結合壓力與細胞外基質硬度的生物物理刺激之下，對於肌肉母細胞分化的影響。
我們使用PA水膠 (polyacrylamide hydrogel)製程方式，利用acrylamide和bis-acrylamide的組成比例不同，來調整PA水膠硬度。再用Sulfo-SANPAH將fibronectin連接於PA水膠表面，以利於H9C2肌肉母細胞附著而生長分化。相對於控制組培養在35mm培養皿中，實驗組則是將H9C2肌肉母細胞於外加靜水壓力10 cmH2O培養48小時。然後用細胞螢光染色方式測定肌肉細胞分化轉錄因子，MyoD和myogenin，表現量在控制組和實驗組之間的差異。根據實驗結果，我們發現H9C2肌肉母細胞附著在不同細胞外基質硬度下，施予外加靜水壓力10 cmH2O皆有促進表現分化轉錄因子，MyoD和myogenin，的傾向。因此實驗結果可能暗示肌肉母細胞在培養過程中，附著於肌肉組織基質硬度範圍的肌肉母細胞，給予適當壓力刺激， 可能會促進肌肉細胞分化和成熟過程。
累積越來越多單一生物化學及物理性訊息刺激對於細胞分化成長影響的知識後，也讓以組織工程的方式來整合細胞所需動態或靜態的分化生長訊息來調控細胞分化及成熟過程和效率的可行性逐漸增加。因此建立一套兩種以上細胞分化生長訊息交互作用的研究方式，對於未來再生醫學和體外細胞實驗可有所助益。Accumulating evidence has demonstrated that integrated biochemical and biophysical microenvironmental cues with accurate temporal and spatial arrangements are needed in cell growth, self-renewal, and differentiation. Although muscle tissue pressure exists during the process of adult injury-induced myogenesis, a dearth of studies showed whether muscle regeneration would be altered when compressive pressure was applied during myoblast differentiation. Thus, the purpose of this study was to investigate the effects of hydrostatic pressure on differentiation of myoblasts, which was cultured on extracellular matrix of different stiffness to simulate the condition of embryonic myogenesis.
We cultured H9C2 myoblasts on fibronectin-coated polyacrylamide hydrogel, of which the stiffness was adjusted by different combinations of acrylamide and bis-acrylamide. Hydrostatic pressure of 10 cmH2O was applied. Then, we examined the expression of myogenesis transcriptional factors, MyoD and myogenin, using immunofluorescence staining. The results revealed that hydrostatic pressure increased the expression of MyoD and myogenin during myoblast differentiation. It might imply that hydrostatic pressure could facilitate the process of myogenesis. Therefore, further studies are merited on the detailed signaling pathways of pressure-induced modulation in myogenesis for developing muscle tissue engineering
Enabling Beyond-Surface Interactions for Tabletop Display with a Depth Camera
No full text近年來，互動桌面顯示系統一直是相當熱門的研究課題。但一般的互動桌面顯示系統都只侷限在桌面上進行操作，本論文希望提出一個新的互動方式有效地將使用者的互動區域擴展至桌面上方的空間而不受限於桌面平面上，進而增加了直覺式操作的可能性。本系統在一般的桌面顯示系統中額外增加了一個深度攝影機，利用其可以偵測物體深度的特性進而計算出物體在3D空間中的位置，再搭配粒子濾波法的追蹤技術，我們可以隨時取得桌面顯示系統與使用者手上行動裝置的空間關係，以達到不同的應用。藉由此技術，本系統實現了平板電腦與桌面顯示系統在桌面以上的互動方式，成功地展示此互動顯示系統的可行性。Interactive surfaces in particular have been received much attention in recent years. Lots of researches have emphasized on this area and try to find more possibilities on the general interactive surface. In this work, we propose a new method let users interact not only on but also beyond the tabletop surface. It is intuitive for users and utilizes the space beyond the surface effectively. We additionally add a depth camera which can compute depth information and 3D positions of objects with the tabletop surface in our system. By integrating with particle filtering, we can figure out the spatial relationship between the tabletop surface and the mobile device in user‘s hands. Based on the proposed techniques, we present an interactive application: imView2 which can let users interact with the surface freely through a tablet PC. It enables beyond-surface interaction and allows more intuitive navigations and is fun to use
The Effect of Investor-pay and Issuer-pay on Credit Rating: An Example of China Corporate Bonds
No full text本文根據萬得資訊和中債資訊提供的債券資料，以上市公司在證券交易所掛牌的中國大陸公司債券為樣本，中債資信評估責任有限公司做為投資人付費的代表，中國大陸其他信用評等機構做為發行人付費的代表，分析投資人付費模式和發行人付費模式對於信用評等高低的影響，並且研究投資人付費模式相較發行人付費模式是否有其他因素能夠更適合的解釋信用評等。先用成對樣本檢定對兩種付費方式進行檢定，並使用順序對數迴歸模型做為主要分析模型，最後利用鄒檢定對各模型的結果進行結構檢定。實證結果顯示，投資人付費的信用評等顯著低於發行人付費的信用評等。在財務特徵資料方面，投資人付費模式和發行人付費模式皆已經充分考慮公開財務資料。在債券特徵資料方面，投資人付費模式的債券發行量、債券距離到期時間和債券掛牌證券交易所都能更合理的解釋對於信用評等的影響。在公司特徵資料方面，投資人付費模式的政治關聯效果、公司治理效果和會計品質效果也都能更合理的解釋對於信用評等的影響。此外，根據鄒檢定的檢定結果，不論是財務特徵資料、債券特徵資料還是公司特徵資料，投資人付費模式和發行人付費模式對於信用評等分析模型的結構都存在顯著的差異。This article analyzes the effect of investor-pay model and issuer-pay model on credit rating. The sample is China corporate bonds listed on securities exchange and the data come from Wind Information and China Credit Rating Corporation. Comparing the ratings issued by China Credit Rating Corporation which follows investor-pay model to those issued by the others rating agencies which adopt the issuer-pay model. First, we test the difference between investor-pay model and issuer-pay model by using Paired Sample Test. Second, we use Ordered Logistic Model to explain the ordinal scale credit rating. Third, we test the structure of the models by using Chow test. Our evidence shows that the credit rating of investor-pay is significantly lower than the credit rating of issuer-pay. In financial characteristic, both investor-pay model and issuer-pay model sufficiently included the public financial information. In bond characteristic, the volume, maturity and listed market of investor-pay can be more appropriate explanation on credit rating. In corporate characteristic, the political connection, corporate governance and audit quality can also be more appropriate explanation on credit rating. Besides, the structures of all models have significant difference.口試委員會審定書……………………………………………………………… i
中文摘要………………………………………………………………………… ii
英文摘要………………………………………………………………………… iii
目錄……………………………………………………………………………… iv
圖目錄…………………………………………………………………………… vi
表目錄…………………………………………………………………………… vii
第一章 緒論…………………………………………………………………… 1
第一節 研究動機………………………………………………………… 1
第二節 研究目的………………………………………………………… 5
第三節 研究架構………………………………………………………… 6
第二章 文獻回顧……………………………………………………………… 7
第一節 評等付費模式…………………………………………………… 7
第二節 不請自來評等…………………………………………………… 9
第三節 雙評等不一致…………………………………………………… 10
第四節 信用評等分析…………………………………………………… 11
第三章 數據資料……………………………………………………………… 13
第一節 研究對象………………………………………………………… 13
第二節 樣本期間………………………………………………………… 14
第三節 資料來源………………………………………………………… 16
第四節 變數定義………………………………………………………… 16
第五節 敘述統計………………………………………………………… 24
第六節 相關分析………………………………………………………… 29
第四章 研究方法……………………………………………………………… 29
第一節 研究方法選定…………………………………………………… 29
第二節 研究模型介紹…………………………………………………… 33
第五章 實證結果……………………………………………………………… 34
第一節 成對樣本檢定…………………………………………………… 34
第二節 順序對數迴歸模型……………………………………………… 37
第三節 鄒檢定…………………………………………………………… 41
第六章 結論建議……………………………………………………………… 43
第一節 結論……………………………………………………………… 43
第二節 研究限制………………………………………………………… 45
第三節 未來研究方向…………………………………………………… 46
參考文獻………………………………………………………………………… 4
Representing Simplified Animation Models using Dynamic Silhouette Clipping
No full text為了減少投影複雜三維動畫模型的時間，以求維持投影時間能夠及時，我們提出以簡化動畫模型套用材質貼圖以及輪廓裁減的方式來逼近原三維動畫模形的外觀。為了紀錄複雜三維動畫模型的法向量資訊，在前置運算中我們建立了法向量地圖，並且在執行運算中將法向量地圖轉為適合簡化動畫模型的材質貼圖。在執行運算中，我們也運用前置運算中分割完成的法向量空間集合來加速尋找複雜三維動畫模型的三維輪廓。運用構成這些輪廓的邊，我們利用OpenGL中的模板快取﹝Stencil Buffer﹞把已投影簡化三維模型中多餘的部份截除。最後我們能以較快的投影速度達成較高的影格更新率﹝Frame Per Second﹞。Considering a sequence of detailed three-dimensional polygonal models, we develop a system framework to approximate them using a pre-computed sequence of coarse three-dimensional polygonal models alone with normal maps. We use the normal maps as information for reconstructing the surface appearance of the original detailed polygonal models. During the runtime of rendering the coarse model sequence, we introduce a simple clustering method to extract the silhouette of detailed three-dimensional polygonal models. We cull the coarse polygonal models by using the silhouette found before to approximate the 2D contours of detailed polygonal models. In order to cull the extra pixels rendered off, we utilize the stencil buffer in OpenGL. To set the stencil value, we also introduce the stencil setting algorithm.Table of Content
CHAPTER 1 INTRODUCTION 8
1.1 MOTIVATION 8
1.2 SYSTEM SKETCH 9
1.3 ORGANIZATION 10
CHAPTER 2 RELATED WORK 11
2.1 LEVEL OF DETAIL/SIMPLIFICATION 11
2.2 SIMPLIFICATION OF DYNAMIC MESHES 13
2.3 SILHOUETTE CLIPPING 16
CHAPTER 3 SYSTEM OVERVIEW 20
3.1 ANIMATION MODELS SIMPLIFICATION 22
3.2 NORMAL MAPS PRODUCING 23
3.3 NORMAL CLUSTERING 23
3.4 SILHOUETTE EXTRACTION 24
3.5 STENCIL SETTING 24
CHAPTER 4 ANIMATION MODELS SIMPLIFICATION 25
4.1 QUADRIC ERROR METRIC (QEM) 25
4.2 DEFORMATION SENSITIVE DECIMATION (DSD) 26
4.3 DEFORMATION ORIENTATION DECIMATION (DOD) 27
4.4 ENLARGEMENT OF ANIMATION MODELS 29
CHAPTER 5 PREPROCESSING STAGE 30
5.1 NORMAL MAPS PRODUCING 30
5.2 EDGE ENCODING 32
5.3 NORMAL CLUSTERING 33
CHAPTER 6 RUNTIME STAGE 34
6.1 TEXTURE CREATION 34
6.2 SILHOUETTES EXTRACTION 35
6.3 STENCIL SETTING 37
CHAPTER 7 RESULTS AND FUTURE WORK 39
7.1 RESULTS 39
7.2 CONCLUSIONS 44
7.3 FUTURE WORK 45
REFERENCE 4
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Variations on the Author
Full text link“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
Full text linkWe 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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