In South Saharan countries, 85% of the population uses biomass as a primary energy source. Cameroon presents one of the highest biomass energy and sawmills produce important sawdust resources which are not used and ar...In South Saharan countries, 85% of the population uses biomass as a primary energy source. Cameroon presents one of the highest biomass energy and sawmills produce important sawdust resources which are not used and are burnt in piles leading to significant air toxic emissions. Therefore, we have to valorize industrially these available sawdusts. This study focuses on the physicochemical and thermochemical analysis of Ayous, Sapelli and Tali sawdust. The proximate and ultimate analysis, particle size, structural composition, as well as heavy metal content and calorific value were determined. In addition, the thermogravimetric mass losses were also estimated. The results showed that high water contents (24% - 41%) were recorded in the raw sawdust, and the thermal treatment reduced these contents from 78% to values in the range of 4% - 9%. The values for ash and volatile matter content were respectively between 0.25% - 0.74% and 68% - 76%. The LHV is higher in Ayous (17.5 MJ/kg) and Sapelli (16.8 MJ/kg) than that of Tali (15.7 MJ/kg). The concentration of heavy metals is very low in each species. Extractives are more present in Tali (16.06%) than in the other sawdusts. Pyrolysis of sawdust shows the typical decomposition of hemicellulose (270˚C - 325˚C), cellulose (325˚C - 400˚C) and lignin (200˚C - 550˚C) with a maximum loss of 75% at 370˚C and the melting point is 320˚C. The results of the sawdust parameters determined in the paper can be valorized to reduce pollutants emissions by developing the efficiency and effectiveness of biomass energy processes and promoting the use of biomass as a sustainable alternative to traditional fossil fuels.展开更多
Late Miocene woods were investigated from the Luhe Basin in Chuxiong Borough, central Yunnan, China. The calcified woods preserved in the Shigucun member of the Shihuiba Formation, are represented by fallen logs and s...Late Miocene woods were investigated from the Luhe Basin in Chuxiong Borough, central Yunnan, China. The calcified woods preserved in the Shigucun member of the Shihuiba Formation, are represented by fallen logs and stumps. Two species of fossil wood, Taxodioxylon cryptomeripsoides Schonfeld 1953 and T. cunninghamioides Watari 1948, are described. Their anatomical structure shows striking similarities to the woods of Cryptomeria and Cunninghamia respectively. That the two fossil woods are classed in the Taxodiaceae suggest a subtropical, humid, and warm environment in Lithe during Late Miocene. They compare favorably to other fossil specimens and species reported from localities ranging from Cretaceous to Pliocene. This is the first record of the presence of the species T. cryptomeripsoides and T. cunninghamioides in late Miocene of Yunnan.展开更多
This thesis,by analyzing the wolf nature,the dog nature and the human nature,and their relations,expounds the author's personal interpretation of the theme of Sherwood Anderson's short story Death in the Woods...This thesis,by analyzing the wolf nature,the dog nature and the human nature,and their relations,expounds the author's personal interpretation of the theme of Sherwood Anderson's short story Death in the Woods.The author maintains that Anderson reveals to readers the ugliness of life and the strange beauty of life,condemns the loss of love and the dehumanization of human life in the modern world and implies Anderson's deep concern on the human alienation,an important theme in the 20th century modern literature.展开更多
Origin of Fengshui Woods was studied, 3 representative standpoints (Fengshui doctrines, greening and worship of the god of land) about Fengshui woods were analyzed, and worship of the god of land was believed as a rea...Origin of Fengshui Woods was studied, 3 representative standpoints (Fengshui doctrines, greening and worship of the god of land) about Fengshui woods were analyzed, and worship of the god of land was believed as a reasonable origin view through considering natural and social factors of ancient China, as well as universal mental characteristics of people in the prescience age. To identify advantages and disadvantages of these 3 views, Carl G. Jung' theory of mythological prototype criticism and Sir James George Frazer's anthropological study were borrowed to prove that Fengshui Woods originated from ancient Chinese worship of the god of land, and such worship gradually evolved into practices of planting Fengshui Woods for their propitious signs. On this basis, enlightenment of Fengshui Woods to modern society was disclosed to protect present Fengshui Woods and forest resources.展开更多
This paper gives a stylistic analysis of the poem "Stopping by Woods on a Snowy Evening" by American poet Robert Frost, and then probes how the author achieves his expected goal through attracting readers...This paper gives a stylistic analysis of the poem "Stopping by Woods on a Snowy Evening" by American poet Robert Frost, and then probes how the author achieves his expected goal through attracting readers' attention and leaving them much space to create their own imagination.展开更多
This paper analyses the justification of paralepsis adopted by Sherwood Anderson,a great American novelist,in his short story Death in the Woods.By using the changing the perspective,typical Anderson’s theme"gro...This paper analyses the justification of paralepsis adopted by Sherwood Anderson,a great American novelist,in his short story Death in the Woods.By using the changing the perspective,typical Anderson’s theme"grotesque"is enhanced.展开更多
Sherwood Anderson is an American famous short story writer.The most enduring work of his is the short story sequence Winesburg,Ohio.He is good at capturing the real sound of everyday speech in his writing and creating...Sherwood Anderson is an American famous short story writer.The most enduring work of his is the short story sequence Winesburg,Ohio.He is good at capturing the real sound of everyday speech in his writing and creating it in new forms and styles.And Death in the Woods is considered as one of his most distinctive stories.It depicts a miserable old woman who feeds others all her life by using symbols to enrich the simple story.This paper intends to reveal the author's deep reflection of American's indifferent and apathetic attitudes in the whole society by means of the symbols of the person,color and dog.展开更多
This work aims at characterizing the evolution of the damage of two tropical hardwoods. Two species from Cameroon, the Entandrophragma Cylindricum and the Chlorora Exelcia were used for the purpose. Repeated compressi...This work aims at characterizing the evolution of the damage of two tropical hardwoods. Two species from Cameroon, the Entandrophragma Cylindricum and the Chlorora Exelcia were used for the purpose. Repeated compressive loading has been made on specimens strictly selected along with longitudinal and radial directions of each species. Each cycle was made of one phase of monotonic loading and a phase of elastic release. From data obtained, we determined the variation of Young modulus and plastic deformation during each cycle of loading, and we had deduced the damage of the material. Results show that the damage appears only after a certain threshold of the plastic deformation;that damage then grows exponentially to reach a threshold after which the failure of the material occurs. As well, we noticed that the growth of damage is accompanied by the progressive decrease of the Young modulus;this confirms the deteriorating effect of the damage on the mechanical properties. Elsewhere, the damage failure threshold is less than the theoretical value, and differs from one direction to another. Finally, we noticed that the damage failure threshold of sapelli is greater than that of iroko that allows concluding that iroko gets damaged and fails more rapidly than sapelli.展开更多
Wood plays a major role in the production of furniture and wooden structures.Nevertheless,in this process,the massive use of adhesives and plural connectors remains a definite problem for health and the environment.Th...Wood plays a major role in the production of furniture and wooden structures.Nevertheless,in this process,the massive use of adhesives and plural connectors remains a definite problem for health and the environment.Therefore,wood welding is a breakthrough in this respect.This paper reviews the applications of wood welding in furniture and construction and then examines advances in improving the durability of welded wood against water.Our contribution also highlights the need to join African tropical woods using the rotational friction welding technique.According to our results,these woods present interesting chemical singularities,which could provide solutions to the water vulnerability of the welded wood.Moreover,the use of such a joining method would first free the Cameroonian furniture industry from the chemical industry,secondly position it at the forefront of new eco-design trends and thirdly make it competitive with other countries in the Central African sub-region.These works enrich the long and rich bibliography on the technique of wood welding,which has long been conspicuous by its absence of tropical woods.展开更多
According to the dara of trashed length, micro fiber angle, air density, ring width and late wood percentage, with the analysis of optimum method of classification, the boundary line of juvenile wood and maturewood of...According to the dara of trashed length, micro fiber angle, air density, ring width and late wood percentage, with the analysis of optimum method of classification, the boundary line of juvenile wood and maturewood of planted Chinese fir (Cunninghamia lanceolata) was determined as the 14th year. Based on the variationpattern of these parameters, the prediction equations were established. Wood quality prediction can be realizedby these equations. By error analysis between the values of measured data and the values of prediction data, it isfound that the results of wood prediction of planted Chinese fire are satisfactory.展开更多
In this paper,the physical and mechanical properties of important Chinese woodswere studied by using the methods of variable analysis, regression analysis,correlation analysis,principle component analysis and so on sy...In this paper,the physical and mechanical properties of important Chinese woodswere studied by using the methods of variable analysis, regression analysis,correlation analysis,principle component analysis and so on systematically.The results showed synthetical characteristicof the physical and mechanical properties of Chinese woods.Some opinions of former authors wererevised and some new laws were discovered.That is helpful to study of the physical and mechanicalproperties of woods.展开更多
文摘In South Saharan countries, 85% of the population uses biomass as a primary energy source. Cameroon presents one of the highest biomass energy and sawmills produce important sawdust resources which are not used and are burnt in piles leading to significant air toxic emissions. Therefore, we have to valorize industrially these available sawdusts. This study focuses on the physicochemical and thermochemical analysis of Ayous, Sapelli and Tali sawdust. The proximate and ultimate analysis, particle size, structural composition, as well as heavy metal content and calorific value were determined. In addition, the thermogravimetric mass losses were also estimated. The results showed that high water contents (24% - 41%) were recorded in the raw sawdust, and the thermal treatment reduced these contents from 78% to values in the range of 4% - 9%. The values for ash and volatile matter content were respectively between 0.25% - 0.74% and 68% - 76%. The LHV is higher in Ayous (17.5 MJ/kg) and Sapelli (16.8 MJ/kg) than that of Tali (15.7 MJ/kg). The concentration of heavy metals is very low in each species. Extractives are more present in Tali (16.06%) than in the other sawdusts. Pyrolysis of sawdust shows the typical decomposition of hemicellulose (270˚C - 325˚C), cellulose (325˚C - 400˚C) and lignin (200˚C - 550˚C) with a maximum loss of 75% at 370˚C and the melting point is 320˚C. The results of the sawdust parameters determined in the paper can be valorized to reduce pollutants emissions by developing the efficiency and effectiveness of biomass energy processes and promoting the use of biomass as a sustainable alternative to traditional fossil fuels.
文摘Late Miocene woods were investigated from the Luhe Basin in Chuxiong Borough, central Yunnan, China. The calcified woods preserved in the Shigucun member of the Shihuiba Formation, are represented by fallen logs and stumps. Two species of fossil wood, Taxodioxylon cryptomeripsoides Schonfeld 1953 and T. cunninghamioides Watari 1948, are described. Their anatomical structure shows striking similarities to the woods of Cryptomeria and Cunninghamia respectively. That the two fossil woods are classed in the Taxodiaceae suggest a subtropical, humid, and warm environment in Lithe during Late Miocene. They compare favorably to other fossil specimens and species reported from localities ranging from Cretaceous to Pliocene. This is the first record of the presence of the species T. cryptomeripsoides and T. cunninghamioides in late Miocene of Yunnan.
文摘This thesis,by analyzing the wolf nature,the dog nature and the human nature,and their relations,expounds the author's personal interpretation of the theme of Sherwood Anderson's short story Death in the Woods.The author maintains that Anderson reveals to readers the ugliness of life and the strange beauty of life,condemns the loss of love and the dehumanization of human life in the modern world and implies Anderson's deep concern on the human alienation,an important theme in the 20th century modern literature.
基金Supported by the Program of Jingdezhen Municipal Joint Association of Social and Scientific Circle (103120401)Staged Fruits of National Natural Science Foundation(41061020)~~
文摘Origin of Fengshui Woods was studied, 3 representative standpoints (Fengshui doctrines, greening and worship of the god of land) about Fengshui woods were analyzed, and worship of the god of land was believed as a reasonable origin view through considering natural and social factors of ancient China, as well as universal mental characteristics of people in the prescience age. To identify advantages and disadvantages of these 3 views, Carl G. Jung' theory of mythological prototype criticism and Sir James George Frazer's anthropological study were borrowed to prove that Fengshui Woods originated from ancient Chinese worship of the god of land, and such worship gradually evolved into practices of planting Fengshui Woods for their propitious signs. On this basis, enlightenment of Fengshui Woods to modern society was disclosed to protect present Fengshui Woods and forest resources.
文摘This paper gives a stylistic analysis of the poem "Stopping by Woods on a Snowy Evening" by American poet Robert Frost, and then probes how the author achieves his expected goal through attracting readers' attention and leaving them much space to create their own imagination.
文摘This paper analyses the justification of paralepsis adopted by Sherwood Anderson,a great American novelist,in his short story Death in the Woods.By using the changing the perspective,typical Anderson’s theme"grotesque"is enhanced.
文摘Sherwood Anderson is an American famous short story writer.The most enduring work of his is the short story sequence Winesburg,Ohio.He is good at capturing the real sound of everyday speech in his writing and creating it in new forms and styles.And Death in the Woods is considered as one of his most distinctive stories.It depicts a miserable old woman who feeds others all her life by using symbols to enrich the simple story.This paper intends to reveal the author's deep reflection of American's indifferent and apathetic attitudes in the whole society by means of the symbols of the person,color and dog.
文摘This work aims at characterizing the evolution of the damage of two tropical hardwoods. Two species from Cameroon, the Entandrophragma Cylindricum and the Chlorora Exelcia were used for the purpose. Repeated compressive loading has been made on specimens strictly selected along with longitudinal and radial directions of each species. Each cycle was made of one phase of monotonic loading and a phase of elastic release. From data obtained, we determined the variation of Young modulus and plastic deformation during each cycle of loading, and we had deduced the damage of the material. Results show that the damage appears only after a certain threshold of the plastic deformation;that damage then grows exponentially to reach a threshold after which the failure of the material occurs. As well, we noticed that the growth of damage is accompanied by the progressive decrease of the Young modulus;this confirms the deteriorating effect of the damage on the mechanical properties. Elsewhere, the damage failure threshold is less than the theoretical value, and differs from one direction to another. Finally, we noticed that the damage failure threshold of sapelli is greater than that of iroko that allows concluding that iroko gets damaged and fails more rapidly than sapelli.
文摘Wood plays a major role in the production of furniture and wooden structures.Nevertheless,in this process,the massive use of adhesives and plural connectors remains a definite problem for health and the environment.Therefore,wood welding is a breakthrough in this respect.This paper reviews the applications of wood welding in furniture and construction and then examines advances in improving the durability of welded wood against water.Our contribution also highlights the need to join African tropical woods using the rotational friction welding technique.According to our results,these woods present interesting chemical singularities,which could provide solutions to the water vulnerability of the welded wood.Moreover,the use of such a joining method would first free the Cameroonian furniture industry from the chemical industry,secondly position it at the forefront of new eco-design trends and thirdly make it competitive with other countries in the Central African sub-region.These works enrich the long and rich bibliography on the technique of wood welding,which has long been conspicuous by its absence of tropical woods.
文摘According to the dara of trashed length, micro fiber angle, air density, ring width and late wood percentage, with the analysis of optimum method of classification, the boundary line of juvenile wood and maturewood of planted Chinese fir (Cunninghamia lanceolata) was determined as the 14th year. Based on the variationpattern of these parameters, the prediction equations were established. Wood quality prediction can be realizedby these equations. By error analysis between the values of measured data and the values of prediction data, it isfound that the results of wood prediction of planted Chinese fire are satisfactory.
文摘In this paper,the physical and mechanical properties of important Chinese woodswere studied by using the methods of variable analysis, regression analysis,correlation analysis,principle component analysis and so on systematically.The results showed synthetical characteristicof the physical and mechanical properties of Chinese woods.Some opinions of former authors wererevised and some new laws were discovered.That is helpful to study of the physical and mechanicalproperties of woods.
