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(1) | 西元年:2001 研究人員(中):杜其永 研究人員(英):TO, KI-WING, Pik-Yin Lai, H. K. Park 研究成果名稱(中):堵塞現象之基礎研究 研究成果名稱(英):Jamming of granular flow 簡要記述(中):大自然與日常生活中顆粒物質到處可見(如雪堆、穀物、砂堆、藥丸乃至公路上的車流…等)。其中顆粒流的堵塞現象—即顆粒系統從流動狀態過渡為靜止狀態的過程—對實際應用方面尤為明顯。長久以來製藥業、工業與農業生產過程中,藥粉、砂土、原料、穀物等顆粒物質的運送經常因堵塞問題而蒙受高額損失。而在台灣造成重大人命與財產損失的土石流現象正是堵塞現象的反向過程。本所研究員杜其永博士以顆粒流流過一個二維漏斗裝置進行堵塞實驗。實驗結果顯示當漏斗出口大於顆粒直徑約五倍時,堵塞機率隨出口變小時而增大以致完全堵塞。從堵塞時顆粒排列的規律可建立簡潔的幾何統計理論並成功的計算出堵塞機率。此成果對顆粒流堵塞現象提供一個清晰而漂亮的基礎理解,同時亦帶領此方面嶄新的定量科學研究方向。此項研究成果於2001年1月1日發表在期刊「物理評論通訊」。由於堵塞現象之基本研究在基礎理論的創新性及其在工、農業方面的實際應用,「物理評論焦點」和「紐約時報」分別於2000年12月27日及2001年1月9日以專文介紹此項研究成果。2001年3月杜其永博士在中央廣播電台「知識經濟探索系列—敖翔新世代」節目中也有詳細報導。 簡要記述(英):It is common knowledge that the flow rate of grains out of a hopper increases with the hopper opening. However, when the hopper opening is comparable to the size of the grain, jamming occurs unpredictably. From observations in experiments and computer simulations, it had been known qualitatively that jamming was due to the formation of an arch before the hopper opening that block the flow. Nevertheless, a quantitative prediction of the probability of jamming is still lacking. We started an extensive study of the jamming phenomenon for mono-disperse disks falling through 2-dimensional hoppers in which the position of every disk is recorded in each jamming event. Then the disk configuration of the jam causing arch was mapped to a trajectory of a restricted random walker (RRW). From the statistics of the RRW trajectories and we estimated the jamming probability as a function of the hopper opening and we found that the statistics of the jamming arch and the probability of jamming obtained in our experiment agreed very well with the theoretical predictions. This work was published in Physical Review Letters and reported in Physical Review Focus. On January 9, 2001 this work was introduced to the general public by an article in New York Times written by Dr. James Glanz. A interview with Dr. Kiwing To on this topic was broadcast by the Radio Taiwan International.
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