1,720,957 research outputs found
陶瓷粉末微射出成型之實驗探討
No full text近年來微量射出成型漸受重視並投入研究，惟陶瓷粉末微量射出成型少有探討。本論文研究使用400nm平均粒徑氧化鋁陶瓷粉末與黏結劑混練造粒後，使用本實驗室開發之衝擊式微量射出成型機來進行厚度200μm及150μm之薄拉伸試片的微射出成型實驗，藉此研究微量粉末射出的製程、操作窗、及成型參數對成品的影響。研究第一部份射出拉伸試片探討氧化鋁在不同射出參數下之成型性，及經過脫脂、燒結後對成品尺寸的影響。第二部份利用透明視窗與高速攝影機觀察不同射出參數在充填不同厚度薄拉伸試片的過程，紀錄陶瓷素料在模穴中的流動情形。
在薄拉伸試片射出成型實驗中，150μm厚度之陶瓷薄件拉伸試片可以成幼g出。並發現射出厚度越薄，衝擊氣壓要越大，也需要更高的模具溫度與融膠溫度來達到完全充填模穴。衝擊氣壓不能太小，否則燒結後翹曲嚴重。較高融膠與模具溫度有較穩定的燒結收縮率。所有實驗參數條件下，長度方向比寬度方向的收縮小。
高速攝影流動觀察發現，衝擊氣壓越小，充填時間越長，且易在澆口處產生流痕，或在離澆口較遠處產生縮孔。隨著氣壓的增加，瞬間充填效應變大；但衝擊氣壓過大也可能產生噴流現象。當射出件越薄，邊界面的影響越大，波前呈現較規則平緩的流動。當射出厚度150μm成品時模具溫度影響相當大；但當融膠溫度高到170℃以上時，模具溫度對充填性的影響就越不明顯。Recently the micro-injection molding has drawn the attention of many researches; but not too much on the micro powder injection molding. This research is devoted to investigating the powder injection molding of micro parts. Al2O3 powders with the average diameter of 400nm compounded with polymer binders can be injection molded to fabricate micro thin tensile test plates. A lab-made impact type micro-injection molding machine was used in this study. There are two aspects in this study: The first one is to study the moldability of the thin parts and to study the effects of processing conditions on molding of micro parts. The second one is to observe the mold filling process in a mold implemented with transparent tempered glass window with aid of high speed video camera.
The results of the first study reveal the impact air pressure has to be high enough to prevent short shots. Increasing the mold and melt temperature can enhance the filling capacity. The thin tensile test plates with the thickness of 150μm can be molded using the impact type micro-injection molding machine. If the green parts are molded with too low air impact pressure, the residual stress of final parts will be high and cause warpage. Consistent shrinkage can be obtained if the green parts are molded with high mold and melt temperatures. The shrinkage along the flow direction is higher than that in across the flow direction.
The observation of the micro powder injection molding during filling process shows that the low impact air pressure causes flow mark and shrinkage holes at the edge far from the gate. On the contrary, too high on impact air pressure can cause the jetting phenomenon. The melt-front during filling the cavity of thin tensile test plates with thickness of 150μm is smoother than those observed in cavity of 200μm thick. When the melt temperature reaches beyond 170℃, the influence of mold temperature upon the filling of 150μm cavity becomes insignificant. The cavity can be filled in less than 0.002 second.中文摘要 Ⅰ
英文摘要 Ⅱ
表目錄 Ⅶ
圖目錄 Ⅸ
第一章 導 論
1-1 前言 1-1
1-2 微量射出成型 1-1
1-3 微量射出成型之研究方向 1-2
1-4 陶瓷粉末射出成型 1-3
1-5 微量陶瓷粉末射出成型之應用 1-4
1-6 微量陶瓷粉末射出成型之問題 1-5
1-7 論文內容架構 1-5
第二章 研究背景與文獻回顧
2-1 微射出成型 2-1
2-2 粉末射出成型 2-2
2-3 微量射出成型機 2-3
2-4 收縮對尺寸精度的影響 2-5
2-5 製程條件與分子定向的關係 2-5
2-6 流動觀察相關研究 2-6
2-7 研究動機與方向 2-7
第三章 實驗設備與步驟
3-1 概述 3-1
3-2 實驗設備 3-1
3-2-1 衝擊式微射出成型機 3-1
3-2-2 模溫控制單元 3-2
3-2-3 融膠單元 3-2
3-2-4 脫模單元 3-3
3-3 模具與實驗材料 3-3
3-3-1 模具 3-3
3-3-2 實驗材料 3-3
3-4 拉伸試片射出成型實驗方法與步驟 3-4
3-4-1 實驗流程 3-4
3-4-2 成型曲線實驗 3-4
3-4-3 拉伸試片實驗參數配置 3-4
3-4-4 熱脫脂 3-5
3-4-5 燒結 3-5
3-4-6 量測方法 3-5
3-5 流動觀察實驗步驟與設備 3-6
3-5-1 流動觀察設備 3-6
3-5-2 實驗方法與步驟 3-6
第四章 拉伸試片射出成型之探討
4-1 拉伸試片成型操作窗之探討 4-1
4-2 衝擊氣壓對拉伸試片射出成型的影響 4-2
4-3 保壓氣壓對拉伸試片射出成型的影響 4-2
4-4 模具溫度對拉伸試片射出成型的影響 4-3
4-5 融膠溫度對拉伸試片射出成型的影響 4-3
4-6 燒結成品厚度的探討 4-4
4-7 拉伸試片成品之厚度對射出成型的影響 4-4
4-8 SEM顯微結構觀察 4-5
4-9 結論與探討 4-5
第五章 拉伸試片流動觀察實驗
5-1 概述 5-1
5-2 流動觀察實驗結果 5-1
5-2-1 衝擊氣壓對充填波前的影響 5-1
5-2-2 保壓氣壓對充填波前的影響 5-2
5-2-3 模具溫度對充填波前的影響 5-2
5-2-4 融膠溫度對充填波前的影響 5-2
5-3 150微米厚拉伸試片充填流動觀察 5-2
5-4 素料於充填過程之流動行為觀察 5-3
5-5 各種射出缺陷現象之觀察 5-4
5-5-1 澆口流痕 5-4
5-5-2 表面縮孔 5-5
5-5-3 噴射流動 5-5
5-5-4 不穩定流動的行為觀察 5-5
5-6 燒結後之成品缺陷 5-6
5-7 結論與探討 5-6
第六章 結論與未來研究方向
6-1 結論 6-1
6-2 未來研究方向 6-2
參考文獻 R-1
附錄A 衝擊式高速微射出機性能對照表 A-1
附錄B 厚度200μm高速攝影拍攝圖 B-1
附錄C 厚度150μm高速攝影拍攝圖 C-
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
sj-tif-2-tag-10.1177_17562848221094959 – Supplemental material for Antireflux mucosal intervention (ARMI) procedures for refractory gastroesophageal reflux disease: a systematic review and meta-analysis
No full textSupplemental material, sj-tif-2-tag-10.1177_17562848221094959 for Antireflux mucosal intervention (ARMI) procedures for refractory gastroesophageal reflux disease: a systematic review and meta-analysis by Jen-Hao Yeh, Ching-Tai Lee, Min-Hung Hsu, Chi-Wen Lin, Po-Jen Hsiao, Chien-Lin Chen and Wen-Lun Wang in Therapeutic Advances in Gastroenterology</p
sj-docx-1-tag-10.1177_17562848221094959 – Supplemental material for Antireflux mucosal intervention (ARMI) procedures for refractory gastroesophageal reflux disease: a systematic review and meta-analysis
No full textSupplemental material, sj-docx-1-tag-10.1177_17562848221094959 for Antireflux mucosal intervention (ARMI) procedures for refractory gastroesophageal reflux disease: a systematic review and meta-analysis by Jen-Hao Yeh, Ching-Tai Lee, Min-Hung Hsu, Chi-Wen Lin, Po-Jen Hsiao, Chien-Lin Chen and Wen-Lun Wang in Therapeutic Advances in Gastroenterology</p
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
- …
