Based on the blasting theory and stress wave theory, stemming mechanism and movement of stemmed material in rock blasting were analyzed and the calculation expression of stemming lengths was deduced. The blasting expe...Based on the blasting theory and stress wave theory, stemming mechanism and movement of stemmed material in rock blasting were analyzed and the calculation expression of stemming lengths was deduced. The blasting experiment with different stemming lengths was carried out and the results show that the theoretical stemming length, which is 0.73 ~ 0.8 time of burden, is in the range of the experiential length, which is O. 63 - O. 88 time of burden. The blasting results of field experiments with theoretical stemming length are satisfactory, which shows the theoretical derivation and analysis are correct and reliable. The results will supply rock blasting with the theoretical gist of parameters design.展开更多
To the Editor：Irreversible electroporation （IRE） is a CE- and FDA- approved treatment modality for pancreatic and liver tumors that is based on the site-confined destruction of tumor tissue by multiple short, high-...To the Editor：Irreversible electroporation （IRE） is a CE- and FDA- approved treatment modality for pancreatic and liver tumors that is based on the site-confined destruction of tumor tissue by multiple short, high-intensity electrical pulses.展开更多
Arabic, as one of the Semitic languages, has a very rich and complex morphology, which is radically different from the European and the East Asian languages. The derivational system of Arabic, is therefore, based on r...Arabic, as one of the Semitic languages, has a very rich and complex morphology, which is radically different from the European and the East Asian languages. The derivational system of Arabic, is therefore, based on roots, which are often inflected to compose words, using a spectacular and a relatively large set of Arabic morphemes affixes, e.g., antefixs, prefixes, suffixes, etc. Stemming is the process of rendering all the inflected forms of word into a common canonical form. Stemming is one of the early and major phases in natural processing, machine translation and information retrieval tasks. A number of Arabic language stemmers were proposed. Examples include light stemming, morphological analysis, statistical-based stemming, N-grams and parallel corpora (collections). Motivated by the reported results in the literature, this paper attempts to exhaustively review current achievements for stemming Arabic texts. A variety of algorithms are discussed. The main contribution of the paper is to provide better understanding among existing approaches with the hope of building an error-free and effective Arabic stemmer in the near future.展开更多
Stemming is used to produce stem or root of words. The process is vital to different research fields such as text mining, sentiment analysis, and text categorization, etc. Several techniques have been proposed to stem...Stemming is used to produce stem or root of words. The process is vital to different research fields such as text mining, sentiment analysis, and text categorization, etc. Several techniques have been proposed to stemming Arabic text and among them, Khoja and light-10 stemmers are the most widely used. In this paper, we propose and evaluate two different stemming techniques to Arabic that are based on light stemming techniques. The new stemmers are compared to best reported light stemmer, which is light-10. Results and experiments, which were conducted using standard collections, reveal that The proposed stemmers yield 5.13% and 13.1% improvement in retrieval performance over light 10 with 0.369 average precision and 0.397, respectively and the improvement is statistically significant.展开更多
During rock drilling and blasting activities,stemming blast holes is to prevent high-pressure explosive gases from the holes,thereby enhancing the overall blasting effectiveness.Hence,it is imperative to investigate t...During rock drilling and blasting activities,stemming blast holes is to prevent high-pressure explosive gases from the holes,thereby enhancing the overall blasting effectiveness.Hence,it is imperative to investigate the dynamic mechanical properties of the stem-ming materials.In this study,impact compression tests were conducted on self-swelling cartridges(SSCs)using a split Hopkinson pres-sure bar(SHPB),aiming to evaluate dynamic performances across strain rate range of 20 to 65 s^(−1).Test results indicate that the dynamic compressive strength of SSCs exhibits the following trends:it increases with increasing density of SSC,decreases with an increase in insertion gap,and follows an initial rise and subsequent fall trend with an increase in water absorption.The order of significance among these factors is density>water absorption>insertion gaps.SSCs exhibit a pronounced strain-rate strengthening dependence in dynamic compressive strength.Furthermore,both the compressive peak stress and peak strain of SSCs follow a well-defined quadratic upward trend with increasing strain rates.As the strain rate increases,the degree of fragmentation,absorbed energy,and dynamic increase factor exhibit an upward trend.Model experimental results indicate that,compared to cementitious stemming materials,SSCs can prolong the duration of gas explosion action.Therefore,SSCs are more suitable for high strain-rate applications such as blasting stemming and rock burst control.展开更多
文摘Based on the blasting theory and stress wave theory, stemming mechanism and movement of stemmed material in rock blasting were analyzed and the calculation expression of stemming lengths was deduced. The blasting experiment with different stemming lengths was carried out and the results show that the theoretical stemming length, which is 0.73 ~ 0.8 time of burden, is in the range of the experiential length, which is O. 63 - O. 88 time of burden. The blasting results of field experiments with theoretical stemming length are satisfactory, which shows the theoretical derivation and analysis are correct and reliable. The results will supply rock blasting with the theoretical gist of parameters design.
文摘To the Editor：Irreversible electroporation （IRE） is a CE- and FDA- approved treatment modality for pancreatic and liver tumors that is based on the site-confined destruction of tumor tissue by multiple short, high-intensity electrical pulses.
文摘Arabic, as one of the Semitic languages, has a very rich and complex morphology, which is radically different from the European and the East Asian languages. The derivational system of Arabic, is therefore, based on roots, which are often inflected to compose words, using a spectacular and a relatively large set of Arabic morphemes affixes, e.g., antefixs, prefixes, suffixes, etc. Stemming is the process of rendering all the inflected forms of word into a common canonical form. Stemming is one of the early and major phases in natural processing, machine translation and information retrieval tasks. A number of Arabic language stemmers were proposed. Examples include light stemming, morphological analysis, statistical-based stemming, N-grams and parallel corpora (collections). Motivated by the reported results in the literature, this paper attempts to exhaustively review current achievements for stemming Arabic texts. A variety of algorithms are discussed. The main contribution of the paper is to provide better understanding among existing approaches with the hope of building an error-free and effective Arabic stemmer in the near future.
文摘Stemming is used to produce stem or root of words. The process is vital to different research fields such as text mining, sentiment analysis, and text categorization, etc. Several techniques have been proposed to stemming Arabic text and among them, Khoja and light-10 stemmers are the most widely used. In this paper, we propose and evaluate two different stemming techniques to Arabic that are based on light stemming techniques. The new stemmers are compared to best reported light stemmer, which is light-10. Results and experiments, which were conducted using standard collections, reveal that The proposed stemmers yield 5.13% and 13.1% improvement in retrieval performance over light 10 with 0.369 average precision and 0.397, respectively and the improvement is statistically significant.
基金supported by the National Natural Science Foundation of China(Nos.51874068 and 52074062)the Open Funds from the Key Laboratory of Ministry of Education on Safe Mining of Deep Metal Mines,Northeastern University,China(No.DM2023B03).
文摘During rock drilling and blasting activities,stemming blast holes is to prevent high-pressure explosive gases from the holes,thereby enhancing the overall blasting effectiveness.Hence,it is imperative to investigate the dynamic mechanical properties of the stem-ming materials.In this study,impact compression tests were conducted on self-swelling cartridges(SSCs)using a split Hopkinson pres-sure bar(SHPB),aiming to evaluate dynamic performances across strain rate range of 20 to 65 s^(−1).Test results indicate that the dynamic compressive strength of SSCs exhibits the following trends:it increases with increasing density of SSC,decreases with an increase in insertion gap,and follows an initial rise and subsequent fall trend with an increase in water absorption.The order of significance among these factors is density>water absorption>insertion gaps.SSCs exhibit a pronounced strain-rate strengthening dependence in dynamic compressive strength.Furthermore,both the compressive peak stress and peak strain of SSCs follow a well-defined quadratic upward trend with increasing strain rates.As the strain rate increases,the degree of fragmentation,absorbed energy,and dynamic increase factor exhibit an upward trend.Model experimental results indicate that,compared to cementitious stemming materials,SSCs can prolong the duration of gas explosion action.Therefore,SSCs are more suitable for high strain-rate applications such as blasting stemming and rock burst control.
