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Numerical Analysis of Double Acting and Single Synthetic Jet
No full text液晶顯示器產業中扮演著關鍵角色的背光模組產業一直是開發創新的焦點，而由於發光二極體具備著低驅動電壓、不含汞、高色再現性等特性，將來取代冷陰極燈管已是必然的趨勢了。但為了要能達到高照度的需求，二極體即便產生高熱密度的問題，在空間有限及低噪音的前提下，具備構造簡單、控制容易等特點的合成噴流便為極具發展潛力的主動式散熱元件。本文以其操作頻率與振幅定義出Re、St 及S三個主要無因次參數，經數值模擬結果的分析後獲悉 主要會影響噴流的渦漩結構及其推進效率，而 主要是影響噴流速度與渦漩強度。最佳化的設計方向為大振幅且高頻率，在此前提下複動式設計對於獨立式合成噴流下游穩定噴流區的改善有限，但兩者在噴口附近的流場則差異甚鉅，複動式合成噴流速度較為集中亦較快且同時具有較長的高速區，因此倘若使用於衝擊冷卻應用之上複動式合成噴流的散熱效率應可較獨立式合成噴流獲得有效地提升。此外 還是影響噴流能否成形的關鍵參數，其倒數值必須大於某常數K才足以產生合成噴流，經本文分析複動式與與獨立式合成噴流的K值約為0.25及0.5。In the backlight module industry, light emitted diode has already been an inevitable trend to replace the cold cathode light, because of characteristics such as the low voltage of urging, no mercury, and high color reproduction. In order to reach the demand for the high intensity of illumination, we should resolve the problem of density of high fever emerging in the diode which will influence the performance of LCD system. Because LCD has limited space and needs low noise, “synthetic jet” is an extremely potential active heat dissipation component possessing the characteristics such as simple structure and easy control. This article uses operating frequency and amplitude of moving boundary to define three main dimensionless parameters—Re,St,and S. After analyzing simulation results, we get two conclusions. On the one hand, increasing St will strengthen the structure of vortex ring and enhance thrusting efficiency. On the other hand, increasing S will enhance the intensity of vortex and increase the jet speed. Under the optimum premise, large amplitude and high frequency, the design of double acting for improving the steady jet region of single synthetic jet is limited. However, the near field of double acting synthetic jet has more concentrating velocity, higher speed, and longer high speed region than single synthetic jet. Therefore, it will have better performance on the application of impinging cooling. In addition, the reciprocal of St must be greater than a constant K to ensure jet formation. According to the results of this article, the values of K of double acting and single synthetic jet are 0.25 and 0.5 eventually.中文摘要 I
英文摘要 Ⅱ
目錄 Ⅲ
表目錄 Ⅵ
圖目錄 Ⅶ
符號說明 XIII
第一章 緒論................................................1
1.1 研究背景............................................1
1.2 可行性分析..........................................6
1.2.1 大尺寸LED液晶電視背光模組之發熱量估算..........6
1.2.2 合成噴流與傳統風扇的散熱效率之比較.............8
1.2.3 複動式與獨立式合成噴流的效能評估..............10
1.3 文獻回顧...........................................11
1.3.1 合成噴流的發展歷程............................12
1.3.2 合成噴流的數值模擬............................15
1.3.3 合成噴流的應用層面............................18
1.4 研究目的與內容.....................................21
第二章 理論模式與數值方法................................23
2.1 合成噴流工作原理...................................23
2.2 數值模擬軟體簡介...................................24
2.3 數值求解流程.......................................26
2.4 空間與時間的離散模式...............................27
2.5 壓力與速度耦合方程式...............................29
2.6 紊流模式...........................................29
2.7 壁面函數...........................................33
2.8 鬆弛因子...........................................33
第三章 軟體二維實例測試與驗證............................35
3.1 軟體驗證：二維實例驗證.............................35
3.2 計算流場說明及格點系統介紹.........................35
3.3 動態網格系統說明...................................36
3.4 基本假設與邊界條件.................................38
3.5 擬週期狀態測試.....................................40
3.6 定義格點系統.......................................41
3.7 移動邊界與進口速度邊界之差異.......................43
3.8 結果驗證...........................................43
3.9 結論...............................................45
第四章 複動式合成噴流數值模擬............................46
4.1 物理計算模型與簡化.................................46
4.2 基本假設與邊界條件說明.............................48
4.3 擬週期狀態測試.....................................50
4.4 定義格點系統.......................................50
4.5 結果驗證...........................................52
4.6 最佳操作條件之驗證.................................54
4.7 結論...............................................56
第五章 流場參數分析結果與討論............................59
5.1 影響合成噴流熱傳效果之因素.........................59
5.2 流場參數...........................................60
5.3 參數控制—固定Reynolds no.，改變Strouhal no.........62
5.4 參數控制—固定Strouhal no.，改變Stokes no. .........66
5.5 形成噴流之臨界條件.................................68
5.6 複動式設計對合成噴流流場結構的影響.................71
5.7 結論...............................................73
第六章 結論與建議........................................75
參考文獻 78
附表 81
附圖 8
Determining Residential Location Choice along the Coastline in Victoria Island, Nigeria Using a Factor Analytical Approach
No full textThis paper evaluates how households consider environmental attributes alongside other housing attributes in their residential location decisions along the coastline in Victoria Island, Nigeria. The data were obtained from tenants’ revealed preference surveys where 204 respondents rated 15 identified and most common key factors in the order by which they influence their residential location choices. The factor analytical approach was then applied to understand how these factors influence such decisions. Thus, this study also gives bearing to the factors considered in making policy and/or investment decisions around residential location choice (RLC). The results revealed the presence of four key components with a total variance of 70.76%. Among the components, neighbourhood, critical dwelling cum socio-economic attributes are found to have a significant influence in explaining 39.78% of the variation in the factors influencing the study area’s selection as the residential location choice (RLC) for households. The findings have implications for households’ residential location choices. For residential locations to be equally attractive to tenants, policymakers and urban planners should pay attention to addressing the menace of the neighbourhoods including crime and traffic congestion. Moreover, property owners should respond to tenants’ needs by paying attention to the provision of utility facilities such as portable water and an appropriate mix of toilet/bathrooms to available bedrooms
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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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counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
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koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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