1,720,967 research outputs found
Study on Production of Furfural from Xylose Catalyzed by Dilute Sulfuric Acid
No full text糠醛是從農業副產品製得的重要化工原料，目前工業製程利用硫酸催化木糖脫去三個水分子而得，不過由於伴隨副反應發生使糠醛產率受限在50%左右[1]，近年已有文獻提出在稀酸溶液中添加氯化鈉有助於提升反應速率以及糠醛產率[2]。然而本研究發現此反應溶液會造成反應器腐蝕問題，其釋放出的金屬離子會影響糠醛生成。本研究建立抗腐蝕與易腐蝕兩種不同反應系統，以動力學關係式探討腐蝕釋出金屬離子對反應之影響，並期望能達到增進糠醛產率的目標。
本研究用Hastelloy C276材質管件與玻璃杯建立抗腐蝕反應系統，以50 mM硫酸催化得到的數據顯示，添加氯化鈉使木糖生成糠醛的反應速率提升約兩倍以上，能有效促進糠醛生成，在180oC時糠醛產率可由硫酸催化時的47.9%增加至57.8%。
在ss304與ss316不鏽鋼組成之易腐蝕反應系統中，50 mM硫酸反應溶液會造成反應器腐蝕並釋放出鐵、鉻、鎳、錳、鉬等金屬離子。實驗結果發現腐蝕釋放出的金屬離子會降低氯化鈉對糠醛產率的影響。但是金屬離子則可以增加木糖生成糠醛的反應速率，並抑制副反應，因此在180oC、50 mM硫酸、及不添加氯化鈉反應條件下，糠醛產率可達75%。顯示不鏽鋼腐蝕釋出之金屬離子優於氯化鈉，能在稀硫酸反應系統中明顯提升糠醛產率。
本研究以在稀硫酸抗腐蝕反應系統中添加金屬氫氧化物或金屬硫酸鹽類進行木糖脫水生產糠醛，期望能模擬及再現腐蝕反應器中之結果。至今之不同添加實驗結果顯示，180oC、50 mM硫酸中如僅添加氫氧化鐵、氫氧化鉻，則反應有最佳的結果，但糠醛產率只能提升至70%。顯示本研究尚未能模擬腐蝕反應系統中所有的反應條件，因此糠醛產率無法提升至稀硫酸腐蝕反應系統中之75%。口試委員會審定書 I
誌謝 II
摘要 III
Abstract IV
目錄 VI
圖索引 VIII
表索引 IX
第一章 緒論 1
1.1 研究背景 1
1.2 研究動機 3
第二章 文獻回顧 5
2.1 糠醛的發展與利用 5
2.2 糠醛的製程 7
2.2.1 一步法製程 7
2.2.2 二步法製程 9
2.3 增進糠醛產率之方法 9
2.3.1 有機溶劑萃取糠醛 10
2.3.2 氯化鈉促進糠醛生成 12
2.3.3 糠醛製程經濟評估 13
2.4 木糖脫水生成糠醛之原理 15
2.4.1 木糖之副反應 16
2.4.2 糠醛之副反應 17
2.4.3 整體反應動力學關係式 18
2.5 金屬腐蝕 20
2.6 金屬材質之選用 21
第三章 實驗與鑑定方法 24
3.1 實驗藥品與器材 24
3.1.1 實驗藥品 24
3.2 實驗器材 25
3.3 實驗裝置 26
3.3.1 反應系統 26
3.3.2 取樣設備 27
3.3.3 抗腐蝕反應系統與易腐蝕反應系統 29
3.4 實驗步驟 31
3.5 沉澱法製備氫氧化物程序 32
3.5.1 氫氧化鐵合成 32
3.5.2 氫氧化亞鐵合成 33
3.5.3 氫氧化鎳合成 34
3.5.4 氫氧化鉻合成 35
3.6 產物分析 37
3.6.1 高效能液相層析 (high performance liquid chromatography, HPLC )37
3.6.2 感應耦合電漿質譜分析 ( Inductively Coupled Plasma-Mass Spectrometer, ICP ) 39
3.7 數據處理 40
3.7.1 轉化率與產率計算 40
3.7.2 速率常數模擬 41
3.7.3 木糖轉化速率常數模擬 42
3.7.4 糠醛最大產率計算 43
第四章 實驗結果與討論 44
4.1 抗腐蝕系統反應探討 44
4.1.1 硫酸催化與硫酸輔以氯化鈉催化之結果比較 44
4.1.2 不同溫度時反應濃度之模擬 45
4.2 易腐蝕系統反應探討 48
4.2.1 硫酸催化與硫酸輔以氯化鈉催化之結果比較 48
4.3 抗腐蝕反應系統與易腐蝕反應系統之比較 49
4.3.1 轉化率與產率變化 49
4.3.2 以速率常數探討反應變化 51
4.4 模擬腐蝕釋出金屬之反應情況 54
4.4.1 腐蝕釋出金屬離子之含量分析 54
4.4.2 硫酸根離子對反應速率影響之探討 55
4.4.3 氫氧根離子對反應速率影響之探討 57
4.4.4 二價鐵離子與三價鐵離子模擬腐蝕釋出金屬離子之反應情況 58
4.4.5 金屬離子對反應影響之探討 61
第五章 結論 64
第六章 參考文獻 67
第七章 附錄-檢測不同反應器之金屬離子成份 a
7.1.1 硫酸濃度對腐蝕釋出金屬濃度之影響 a
7.1.2 溫度對腐蝕釋出金屬濃度之影響 b
7.1.3 氯化鈉對腐蝕釋出金屬濃度之影響
Business Model Innovation via Digital Payment and Ecosystem Integration for Night Market
No full text集合攤商所形成的夜市文化是台灣文化中重要的一環，但隨著國民生活水準的提高，夜市攤販的水準卻無法跟進，探索其原因的根本在於攤商沒有多餘的心力與時間來思考如何提升夜市整體的水準，因為攤販在整個交易過程中，必須自己處理物流、金流與現場溝通，也因此造成整體水準停滯不前的情況。 本論文將利用現代人人手一機且隨處上網的特性及近場通訊技術將消費者與攤商及攤商與其供應商的交易資訊全部儲存在雲端資料庫，並利用該資料庫與供應商進行食材採購的議價與對消費者進行行銷，支付過程透過塑膠貨幣進行電子支付，減少現金交易的新交易模式來達到幫助攤商提高獲利率及獲得更多時間思考策略性的計劃，包括制定SOP或執行拓點計畫。同時，消費者可透過查詢過去的消費店家、金額及其供應商，建立起對食品安全的信心。透過一個雲端資料庫串聯起攤商、供應商與消費者形成一個價值創造循環，利用資料庫進行分析，進而不斷提升夜市的水準。 透過全新的電子交易方式及雲端資料儲存庫，能夠減少攤商收到假鈔的機會，增加夜市整體的清潔度，同時利用資料庫的透明度解決食安問題，大數據分析市場整體狀況，提高攤商效率工時，增加店家差異化程度的意願，減少攤商本身的存貨需求，降低吃霸王餐的機會，這些都是過去未使用雲端資料庫所無法解決的問題，藉由這一模式將能夠解決全部問題，讓攤商提升利潤率的同時擁有更多時間思考，進而提升整體夜市水準。Night market culture collected by vendors is one of the most important Taiwanese culture. But with the increasing GDP and living standard, it seems no more advanced process applied to night market. Vendors still use the way they used to be, which is trading service or goods in cash. The root cause is they don’t have too much time to think about improvement, because they have to deal with not only information flow, but also goods flow, even cash flow during the whole process, that makes them exhausted so the level of night market couldn’t level up. This essay will use cell phone, internet and NFC technology to create a new business model for both customers and vendors, even vendors with its suppliers can use this system. We will build a database in cloud, and all information will be stored into it. Because we will order materials as an union rather than single vender, it would be easily to get better price or high quality materials from suppliers. And we will do some marketing to customer, let them understand what benefit they can get from this system. Instead of using cash, customers will use their RFID card to pay for goods and service. Because it will save time for vendors, they won’t need to rush into bank or identify whether the bill is fake or not during the sales. It will give vendors more time to think about strategic plans, such as where to extent to or how to set up a SOP. Meanwhile, customers can check not only where they had been for meals but also how much they spent on each vendor on app. It can make customer feel safe cause the supply chain is also transparent enough for them. Through a database in cloud, we can connect vendors, customers and suppliers to form a VCC. By using this new payment system and database, it will bring several benefits, such as reducing the opportunity of receiving fake bill, increasing hygiene in night market, decreasing vendor’s inventory demand, analyzing whole market share etc.. Above questions couldn''t solve in the past due to technical issue, but we can solve it now, it gives vendors not only profit but also time to think and consider how to improve in the future
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
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
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
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
sophisticated methods
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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