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題 名 | 脫溼過程中柳杉木材超音波傳遞速度與平均含水率之關係=Relationship between Ultrasonic Velocity and Average Moisture Content in Japanese Ceder during Desorption Process |
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作 者 | 卓志隆; 溫惠淑; | 書刊名 | 林產工業 |
卷 期 | 25:4 民95.12 |
頁 次 | 頁261-269 |
分類號 | 474.28 |
關鍵詞 | 柳杉; 含水率; 超音波傳遞速度; 含髓心材; 正常材; 反應材; Cryptomeria japonica; Moisture content; Ultrasonic wave velocity; Boxed pith wood; Normal wood; Reaction wood; |
語 文 | 中文(Chinese) |
中文摘要 | 在木材乾燥過程中,確實掌握木材含水率變化是非常重要的,傳統的樣板法在測定材堆中木材含水率時有諸多缺點,因此開發一種簡單易操作的非破壞檢測技術用來測定乾燒過程中木材含水率的變化,具有實用的價值。本研究以超音波技術探討柳杉含髓心材、未含髓心正常材及反應材從飽水狀態至絕乾過程中,縱向、徑向及弦向超音波傳遞速度與平均含水率的關係。試驗結果顯示,反應材及會髓心材之縱向傳遞速度較正常材低,但徑向及弦向傳遞速度則會較高。含水率在纖維飽和點以上時,因含水率梯度造成之效應,隨著含水率降低,傳遞速度會緩和地增大,在纖維飽和點以下時,隨著含水率降低,各方向的速度皆會明顯地增大。以雙對數迴歸模式分析超音波傳遞速度與含水率的關係,其決定係數相當高,以此模式所推算的含水率與實測值差異在纖維飽和點以下時較小且以徑向或弦向速度所推算的含水率準確性較高,平均誤差約為2%。 |
英文摘要 | It is very important to realize exactly changes of moisture content during wood drying process. There are many disadvantages using traditional sample board method to determine moisture content of lumber during kiln drying. The development of a convenient non-destructive technique could measure moisture content in wood from green condition to expected moisture content would be valuable. In this study, ultrasonic technique was used to investigate wave velocity variations in the longitudinal, radial and tangential directions of Japanese cedar from water-saturated condition to oven dry moisture content. Three types of test specimens were normal wood, reaction wood and boxed pith wood. Results indicated that ultrasonic wave velocities in the fiber direction of boxed pith wood and reaction wood were lower than normal wood, but those in the radial and tangential directions were greater than normal wood. In the moisture content range above fiber saturation point (FSP), the ultrasonic wave velocities tended to increase with decrease in moisture content attributed to the moisture gradient in wood samples. The effect of moisture content on the ultrasonic wave velocity below FSP was more significant than those above the FSP. Moisture content is very closely related to ultrasonic wave velocity according to dual logarithmic regression model analysis. The difference between estimated moisture content from regression model and measured data below FSP was smaller than those above FSP. Average error between estimated moisture content by radial or tangential velocity and measured moisture content below FSP was approximate2%, which was more accurate than those by longitudinal velocity. |
本系統中英文摘要資訊取自各篇刊載內容。