This paper analyzed the strata behaviors of solid-coal roadway, gob-side entry driving and deformation law of surrounding rock in depth under high stress and thick composite roof based on the dynamic pressure roadway ...This paper analyzed the strata behaviors of solid-coal roadway, gob-side entry driving and deformation law of surrounding rock in depth under high stress and thick composite roof based on the dynamic pressure roadway as engineering background in Fengcheng mining area, Jiangxi province. The results, both field measurement and numerical simulation show that gob-side entry driving results the deformation of coal roadway main wall, however, entity-coal roadway driving results deformation of main roof and floor. The maintenance state of gob-side entry driving is better than entity-coal roadway, this situation is relevant to thick composite roof layered and easy collapse characteristics. At the same time, this paper put fox＇ward and proved proper dynamic pressure roadway supporting scheme under the surrounding rock condition and stress environment.展开更多
Xiamen Bay in South China has experienced extensive coastal exploitation since the 1950s,resulting in some severe environmental problems.Local authorities now have completed or are implementing many environmental rest...Xiamen Bay in South China has experienced extensive coastal exploitation since the 1950s,resulting in some severe environmental problems.Local authorities now have completed or are implementing many environmental restoration projects.Evaluating the cumulative impact of exploitation and restoration activities on the environment is a complicated multi-disciplinary problem.However,hydrodynamic changes in the bay caused by such coastal projects can be characterized directly and definitively through numerical modeling.This paper assesses the cumulative effect of coastal projects on the hydrodynamic setting using a high-resolution numerical modeling method that makes use of tidal current speeds and the tidal prism as two hydrodynamic indices.Changes in tidal velocity and the characteristics of the tidal prism show that hydrodynamic conditions have declined from 1938 to 2007 in the full-tide area.The tidal current speed and tidal prism have decreased by 40% in the western part of the bay and 20% in the eastern part of the bay.Because of the linear relationship between tidal prism and area,the degraded hydrodynamic conditions are anticipated to be restored to 1972 levels following the completion of current and proposed restoration projects,i.e.33% and 15% decrease in the hydrodynamic conditions of 1938 for the western and eastern parts of the bay,respectively.The results indicate that hydrodynamic conditions can be restored to some extent with the implementation of a sustainable coastal development plan,although a full reversal of conditions is not possible.To fully assess the environmental changes in a region,more indices,e.g.,water quality and ecosystem parameters,should be considered in future evaluations.展开更多
In this study,we integrated a DNA barcoding project with an ecological survey on intertidal polychaete communities and investigated the utility of CO1 gene sequence as a DNA barcode for the classification of the inter...In this study,we integrated a DNA barcoding project with an ecological survey on intertidal polychaete communities and investigated the utility of CO1 gene sequence as a DNA barcode for the classification of the intertidal polychaetes.Using 16S rDNA as a complementary marker and combining morphological and ecological characterization,some of dominant and common polychaete species from Chinese coasts were assessed for their taxonomic status.We obtained 22 haplotype gene sequences of 13 taxa,including 10 CO1 sequences and 12 16S rDNA sequences.Based on intra-and inter-specific distances,we built phylogenetic trees using the neighbor-joining method.Our study suggested that the mitochondrial CO1 gene was a valid DNA barcoding marker for species identification in polychaetes,but other genes,such as 16S rDNA,could be used as a complementary genetic marker.For more accurate species identification and effective testing of species hypothesis,DNA barcoding should be incorporated with morphological,ecological,biogeographical,and phylogenetic information.The application of DNA barcoding and molecular identification in the ecological survey on the intertidal polychaete communities demonstrated the feasibility of integrating DNA taxonomy and ecology.展开更多
Phytoplankton abundance was found to be positively correlated with seasonal changes of seawater temperature in Port Shelter and Lamma Channel, Hong Kong in 1998. Rising water temperature from around 20℃ to 25℃ coinc...Phytoplankton abundance was found to be positively correlated with seasonal changes of seawater temperature in Port Shelter and Lamma Channel, Hong Kong in 1998. Rising water temperature from around 20℃ to 25℃ coincided with an increase in phytoplankton abundance at both locations. Heavy rains from June to September reduced salinity from 30 to 20, but the decrease in salinity was not correlated with a decline in phytoplankton abundance. In spring 1998, over 0.6×10^6 cells dm^-3 and 0.1× 10^6 cells dm^-3 of the dinoflagellate, Gymnodinium mikimotoi Miyake et Kominami ex Oda occurred in the coastal waters of Port Shelter and Lamina Channel, respectively. High abundance of the dinoflagellate Ceratium furca （Ehr.） Claparede et Lachmann （〉1×10^6 cells dm^-3） produced long-lasting blooms in the waters of Port Shelter from September to October in 1998. The abundances of both diatoms and dinoflagellates were significantly lower in the waters of Lamina Channel than those in Port Shelter due to the less frequent blooms in 1998. Hydrographic conditions such as stable water masses and water column stratification were the main reasons for the differences in the algal abundance and bloom frequency found between the two locations since neither of the two areas appeared to be nutrient-limited. This type water condition for the formation of algal bloom in Port Shelter has not been reported previously and it is not a general case for many bays along China＇s coast where algal bloom occurs as well.展开更多
In the context of current climate change, an abnormality of flooding is a common form of disaster in Vietnam. Hanh Stream reservoir has occurred great flood in 1986, 2010. In the future, the risk of flooding is possib...In the context of current climate change, an abnormality of flooding is a common form of disaster in Vietnam. Hanh Stream reservoir has occurred great flood in 1986, 2010. In the future, the risk of flooding is possible to happen again. In view of management of the risk of natural disasters： large flooding situation downstream is one of the most dangerous risks for the reservoir. Due to downstream of Hanh Stream reservoir is a narrow coastal plains, quick infrastructure development, especially interwoven road and railway systems, so that flood drainage ability will be affected greatly. The consciousness of risks that may be occurred in the future in order to propose preventive measures and proactive response to minimize damages always is the requirement for all projects. The hydrodynamic calculation, flooding maps, emergency plan to prevent flooding downstream of Hanh Stream reservoir is also needed. The article is raised the issue of requirements to calculate coastal narrow delta strip flooding in the Central of Vietnam when impacted by the upstream reservoir of flood discharge in terms of extreme heavy rain and flooding and presented computational methods of Mike software package for case flooded plain of Cam Ranh Bay in downstream reservoirs of Hanh Stream, Khanh Hoa Province, Vietnam.展开更多
An algorithm developed at the University of Botswana is used to study solar radiation conditions in Namibia, South Africa, Mozambique and Botswana. The synoptic stations chosen for the study differ by meteorological c...An algorithm developed at the University of Botswana is used to study solar radiation conditions in Namibia, South Africa, Mozambique and Botswana. The synoptic stations chosen for the study differ by meteorological conditions and location： some are in coastal areas and others are in continental locations. The simulation results reveal that daily direct beam solar radiation, Hbn, is usually higher in the continental area than in the coastal one. The same situation is observed with daily global solar radiation, Hg. The difference becomes even larger for partly cloudy weather, because in coastal areas sunshine hours are usually less than in continental areas. Furthermore, coastal areas have higher humidity and bigger air mass compared to continental locations. It is concluded that continental areas are more convenient for utilisation of solar energy using solar devices with concentrators （middle-temperature and high-temperature Rankine cycles）, while at coastal areas flat-plate collectors and PV-arrays are preferable. It is found out that the range of optimum slopes for SADC countries studied is from ＋30° to -62°.展开更多
基金Supported by the National Natural Science Foundation of China （51074071） the Scientific Research Fund of Hunan Provincial Education Department （12cy013）
文摘This paper analyzed the strata behaviors of solid-coal roadway, gob-side entry driving and deformation law of surrounding rock in depth under high stress and thick composite roof based on the dynamic pressure roadway as engineering background in Fengcheng mining area, Jiangxi province. The results, both field measurement and numerical simulation show that gob-side entry driving results the deformation of coal roadway main wall, however, entity-coal roadway driving results deformation of main roof and floor. The maintenance state of gob-side entry driving is better than entity-coal roadway, this situation is relevant to thick composite roof layered and easy collapse characteristics. At the same time, this paper put fox＇ward and proved proper dynamic pressure roadway supporting scheme under the surrounding rock condition and stress environment.
基金Supported by the National Natural Science Foundation of China(Nos.41076001,40810069004)the Fundamental Research Funds for the Central Universities(No.2010121029)
文摘Xiamen Bay in South China has experienced extensive coastal exploitation since the 1950s,resulting in some severe environmental problems.Local authorities now have completed or are implementing many environmental restoration projects.Evaluating the cumulative impact of exploitation and restoration activities on the environment is a complicated multi-disciplinary problem.However,hydrodynamic changes in the bay caused by such coastal projects can be characterized directly and definitively through numerical modeling.This paper assesses the cumulative effect of coastal projects on the hydrodynamic setting using a high-resolution numerical modeling method that makes use of tidal current speeds and the tidal prism as two hydrodynamic indices.Changes in tidal velocity and the characteristics of the tidal prism show that hydrodynamic conditions have declined from 1938 to 2007 in the full-tide area.The tidal current speed and tidal prism have decreased by 40% in the western part of the bay and 20% in the eastern part of the bay.Because of the linear relationship between tidal prism and area,the degraded hydrodynamic conditions are anticipated to be restored to 1972 levels following the completion of current and proposed restoration projects,i.e.33% and 15% decrease in the hydrodynamic conditions of 1938 for the western and eastern parts of the bay,respectively.The results indicate that hydrodynamic conditions can be restored to some extent with the implementation of a sustainable coastal development plan,although a full reversal of conditions is not possible.To fully assess the environmental changes in a region,more indices,e.g.,water quality and ecosystem parameters,should be considered in future evaluations.
基金Supported by the National Natural Science Foundation of China(No.40730847&40906063)the Student Research Training Program of Ocean University of China(No.0811010509)
文摘In this study,we integrated a DNA barcoding project with an ecological survey on intertidal polychaete communities and investigated the utility of CO1 gene sequence as a DNA barcode for the classification of the intertidal polychaetes.Using 16S rDNA as a complementary marker and combining morphological and ecological characterization,some of dominant and common polychaete species from Chinese coasts were assessed for their taxonomic status.We obtained 22 haplotype gene sequences of 13 taxa,including 10 CO1 sequences and 12 16S rDNA sequences.Based on intra-and inter-specific distances,we built phylogenetic trees using the neighbor-joining method.Our study suggested that the mitochondrial CO1 gene was a valid DNA barcoding marker for species identification in polychaetes,but other genes,such as 16S rDNA,could be used as a complementary genetic marker.For more accurate species identification and effective testing of species hypothesis,DNA barcoding should be incorporated with morphological,ecological,biogeographical,and phylogenetic information.The application of DNA barcoding and molecular identification in the ecological survey on the intertidal polychaete communities demonstrated the feasibility of integrating DNA taxonomy and ecology.
基金Supported by the Project for Coastal Sea Investigation and Assessment in China (No. 908-02-03-09, 908-01-ST06and FJ908-01-01-HS)the Natural Science Foundation of China (No.10705019)
文摘Phytoplankton abundance was found to be positively correlated with seasonal changes of seawater temperature in Port Shelter and Lamma Channel, Hong Kong in 1998. Rising water temperature from around 20℃ to 25℃ coincided with an increase in phytoplankton abundance at both locations. Heavy rains from June to September reduced salinity from 30 to 20, but the decrease in salinity was not correlated with a decline in phytoplankton abundance. In spring 1998, over 0.6×10^6 cells dm^-3 and 0.1× 10^6 cells dm^-3 of the dinoflagellate, Gymnodinium mikimotoi Miyake et Kominami ex Oda occurred in the coastal waters of Port Shelter and Lamina Channel, respectively. High abundance of the dinoflagellate Ceratium furca （Ehr.） Claparede et Lachmann （〉1×10^6 cells dm^-3） produced long-lasting blooms in the waters of Port Shelter from September to October in 1998. The abundances of both diatoms and dinoflagellates were significantly lower in the waters of Lamina Channel than those in Port Shelter due to the less frequent blooms in 1998. Hydrographic conditions such as stable water masses and water column stratification were the main reasons for the differences in the algal abundance and bloom frequency found between the two locations since neither of the two areas appeared to be nutrient-limited. This type water condition for the formation of algal bloom in Port Shelter has not been reported previously and it is not a general case for many bays along China＇s coast where algal bloom occurs as well.
文摘In the context of current climate change, an abnormality of flooding is a common form of disaster in Vietnam. Hanh Stream reservoir has occurred great flood in 1986, 2010. In the future, the risk of flooding is possible to happen again. In view of management of the risk of natural disasters： large flooding situation downstream is one of the most dangerous risks for the reservoir. Due to downstream of Hanh Stream reservoir is a narrow coastal plains, quick infrastructure development, especially interwoven road and railway systems, so that flood drainage ability will be affected greatly. The consciousness of risks that may be occurred in the future in order to propose preventive measures and proactive response to minimize damages always is the requirement for all projects. The hydrodynamic calculation, flooding maps, emergency plan to prevent flooding downstream of Hanh Stream reservoir is also needed. The article is raised the issue of requirements to calculate coastal narrow delta strip flooding in the Central of Vietnam when impacted by the upstream reservoir of flood discharge in terms of extreme heavy rain and flooding and presented computational methods of Mike software package for case flooded plain of Cam Ranh Bay in downstream reservoirs of Hanh Stream, Khanh Hoa Province, Vietnam.
文摘An algorithm developed at the University of Botswana is used to study solar radiation conditions in Namibia, South Africa, Mozambique and Botswana. The synoptic stations chosen for the study differ by meteorological conditions and location： some are in coastal areas and others are in continental locations. The simulation results reveal that daily direct beam solar radiation, Hbn, is usually higher in the continental area than in the coastal one. The same situation is observed with daily global solar radiation, Hg. The difference becomes even larger for partly cloudy weather, because in coastal areas sunshine hours are usually less than in continental areas. Furthermore, coastal areas have higher humidity and bigger air mass compared to continental locations. It is concluded that continental areas are more convenient for utilisation of solar energy using solar devices with concentrators （middle-temperature and high-temperature Rankine cycles）, while at coastal areas flat-plate collectors and PV-arrays are preferable. It is found out that the range of optimum slopes for SADC countries studied is from ＋30° to -62°.
