With the increasing demand for high torque density in motors,more and more new topologies emerge.Furthermore,the magnetic field modulation principle is widely concerned and has evolved into an effective analysis metho...With the increasing demand for high torque density in motors,more and more new topologies emerge.Furthermore,the magnetic field modulation principle is widely concerned and has evolved into an effective analysis method for studying the new motor topology.This paper introduces the principle of magnetic field modulation.And the research on high torque density in recent years is reviewed from the perspective of magnetic field modulation,including permanent magnet vernier machine(PMVM),flux reverse machine(FRM),flux switching machine(FSM),dual permanent magnet(DPM)machine,and DC biased machine.The principle of magnetic field modulation makes it possible to propose higher torque density topologies in the future.展开更多
The present study examines the extent of negative eff ects of traditional multiple land-use systems on oak coppices,from a forest management point of view.The study area was located in approximately 10,000 ha of hilly...The present study examines the extent of negative eff ects of traditional multiple land-use systems on oak coppices,from a forest management point of view.The study area was located in approximately 10,000 ha of hilly Brant’s oak(Quercus brantii Lindl.)woodlands in the central Zagros Mountains.In the same site-quality class,three land-use systems were compared:simple coppice(Co),coppice in conjunction with small ruminant grazing(CoG),and coppice with understory rain-fed wheat cultivation plus grazing(CoCG).Data on total wood volume of trunk and major branches,and annual ring growth,were collected and analyzed from 74 stands in 15 coppiced woodland patches.The results showed the advantage of Co over CoG and CoCG land-uses by 43 and 60 m 3 of mean accumulated wood volume per hectare,respectively.The diameter growth analysis also revealed an annual increase in wood production of trees in Co land-uses over 43 years,with an exception of the recent decade,when growth coincided with a severe drought.Using a back-extrapolation method,the minimum rotation age of woodlands in Co land-use was found to be 23.6 years,5 and 7 years shorter than those of CoG and CoCG land-uses,respectively.Unlike CoCG,woodlands located in Co and CoG land-use systems demonstrated a high level of agreement with self-thinning rule of−3/2.Values for the stand density index for coppiced oak woodlands were between more than 1000 for the least disturbed(Co)and less than 400 for the most disturbed woodlands(CoCG).The structure and growth rate of the coppiced oak woodlands were irreversibly disrupted by understory tillage plus grazing and in less extent by grazing alone.It was concluded that ending undergrowth cultivation in semi-arid oak coppices should be addressed as a priority by adopting minimum regulations.展开更多
Dynamic nonlinearities of C70/toluene solution are measured and analysed by an improved picosecond timeresolved pump-probe system based on a nonlinear imaging technique with phase object. The photophysical parameters ...Dynamic nonlinearities of C70/toluene solution are measured and analysed by an improved picosecond timeresolved pump-probe system based on a nonlinear imaging technique with phase object. The photophysical parameters are determined by the five-level model, which is adopted to interpret the experimental data. The change of refraction index per unit density of the excited state obtained by a numerically simulation is a critical factor to determine the nonlinear behaviour of C70 in picosecond time regime.展开更多
Understanding the relationship between the timing of N fertilizer applications and crop primary production is crucial for achieving high yield and N use efifciency in agriculture. This study investigated the effects o...Understanding the relationship between the timing of N fertilizer applications and crop primary production is crucial for achieving high yield and N use efifciency in agriculture. This study investigated the effects of starting-N plus topdressing N applications (as compared to the common practice of all basal application) on soybean photosynthetic capacity under different planting densities. A ifeld experiment was conducted in two growing seasons (2011 and 2012), and the soybean (Glycine max L. Merrill) cultivar was Dongnong 52, three planting densities (20, 25 and 30 plants m-2), and four N fertilizer application patterns (all N fertilizer of 6 g N m-2 as basal fertilizer, all N fertilizer as topdressing at beginning pod stage (R3), 1.8 g N m-2 as basal fertilizer and 4.2 g N m-2 as topdressing at stage R3 and full pod stage (R4), respectively). The results indicated that under the same planting density, compared to applying all N as basal fertilizer, the application of starter-N plus topdressing N substantially reduced the rate of pod abscission, and enhanced leaf area index (LAI) signiifcantly at beginning seed stage (R5) (P〈0.05), net assimilation rate (NAR) during stages R4-full seed stage (R6) (P〈0.05), contribution rate of post-seed iflling assimilate to seed (CPA) (P〈0.05), and yield (P〈0.05). Applying topdressing N at stage R4 resulted in higher net primary production and yield than applying topdressing N at stage R3. When applying starter-N plus topdressing N at planting density of 25 plants m-2, LAI after stage R5 and NAR after stage R4 were increased by 5.92-16.3%(P〈0.05) and 13.7-26.6%(P〈0.05) with the planting density of 20 plants m-2, respectively, and yield was 8.46-14.0%(P〈0.05) higher than that under 20 plants m-2. When planting density increased to 30 plants m-2, only LAI during stages R4-R5 and NAR during stages R4-R5 increased by applying starter-N plus topdressing N, while the other indexes declined. Overall, results of this study demonstrated that applying starter-N plus topdressing N could signiifcantly enhance soybean photosynthetic capacity after stage R5 at planting density of 25 plants m-2.展开更多
As Iran is located on one of the two earthquake-prone belts in the world, and existence of faults and earthquakes is normal in Iran tableland. The main reason of earthquake is Neotectonic movements which can be effect...As Iran is located on one of the two earthquake-prone belts in the world, and existence of faults and earthquakes is normal in Iran tableland. The main reason of earthquake is Neotectonic movements which can be effective in other natural disasters such as range movements. Due to the severe shortage of historical and seismic data and device in different parts of the world, particularly Iran, need for introducing more researchers and planners of Iran to tectonics and active tectonic areas is more visible. This study is an investigation of Neotectonic activities in Khafr basin area, Fars province. To achieve the aims of this study morphometric parameters were used. Investigations showed that severity and role of tectonic activities in different parts of the basin is different, results of geomorphic and tectonic assessments indicate these differences.Stream length-gradient index (SL) on the main stream is inactive and sub streams are semi active, the ratio of the basin (BS) is 2.27, drainage basin asymmetry index (AF) is in semi active class, the ratio of width to depth of Valley (VF) shows 0.78. Indicators mentioned are in class 3 based on Iat classification, that represents tectonic activity in the area is average. Other indicators are indicative of active tectonic in the basin such as drainage density index (D) with high density, river sinuosity (S) 1.25, reverse topography symmetry Factor (T) 0.3.Generally it can be considered as moderately active region in terms of tectonic activities.展开更多
The density based notion for clustering approach is used widely due to its easy implementation and ability to detect arbitrary shaped clusters in the presence of noisy data points without requiring prior knowledge of ...The density based notion for clustering approach is used widely due to its easy implementation and ability to detect arbitrary shaped clusters in the presence of noisy data points without requiring prior knowledge of the number of clusters to be identified. Density-based spatial clustering of applications with noise (DBSCAN) is the first algorithm proposed in the literature that uses density based notion for cluster detection. Since most of the real data set, today contains feature space of adjacent nested clusters, clearly DBSCAN is not suitable to detect variable adjacent density clusters due to the use of global density parameter neighborhood radius Y,.ad and minimum number of points in neighborhood Np~,. So the efficiency of DBSCAN depends on these initial parameter settings, for DBSCAN to work properly, the neighborhood radius must be less than the distance between two clusters otherwise algorithm merges two clusters and detects them as a single cluster. Through this paper: 1) We have proposed improved version of DBSCAN algorithm to detect clusters of varying density adjacent clusters by using the concept of neighborhood difference and using the notion of density based approach without introducing much additional computational complexity to original DBSCAN algorithm. 2) We validated our experimental results using one of our authors recently proposed space density indexing (SDI) internal cluster measure to demonstrate the quality of proposed clustering method. Also our experimental results suggested that proposed method is effective in detecting variable density adjacent nested clusters.展开更多
基金supported in part by the National Natural Science Foundation of China(NSFC)under Project No.51737010the National Key R&D Program of China under Grant 2020YFA0710500。
文摘With the increasing demand for high torque density in motors,more and more new topologies emerge.Furthermore,the magnetic field modulation principle is widely concerned and has evolved into an effective analysis method for studying the new motor topology.This paper introduces the principle of magnetic field modulation.And the research on high torque density in recent years is reviewed from the perspective of magnetic field modulation,including permanent magnet vernier machine(PMVM),flux reverse machine(FRM),flux switching machine(FSM),dual permanent magnet(DPM)machine,and DC biased machine.The principle of magnetic field modulation makes it possible to propose higher torque density topologies in the future.
基金We express our appreciation to the 2018 forestry graduate students’team for their great help in data collection.We also gratefully acknowledge the Provincial Natural Resources Bureau for providing us with their archive of journey reports and grazing license contracts.Finally,we appreciate the anonymous reviewers who carefully read the manuscript and made many insightful comments.
文摘The present study examines the extent of negative eff ects of traditional multiple land-use systems on oak coppices,from a forest management point of view.The study area was located in approximately 10,000 ha of hilly Brant’s oak(Quercus brantii Lindl.)woodlands in the central Zagros Mountains.In the same site-quality class,three land-use systems were compared:simple coppice(Co),coppice in conjunction with small ruminant grazing(CoG),and coppice with understory rain-fed wheat cultivation plus grazing(CoCG).Data on total wood volume of trunk and major branches,and annual ring growth,were collected and analyzed from 74 stands in 15 coppiced woodland patches.The results showed the advantage of Co over CoG and CoCG land-uses by 43 and 60 m 3 of mean accumulated wood volume per hectare,respectively.The diameter growth analysis also revealed an annual increase in wood production of trees in Co land-uses over 43 years,with an exception of the recent decade,when growth coincided with a severe drought.Using a back-extrapolation method,the minimum rotation age of woodlands in Co land-use was found to be 23.6 years,5 and 7 years shorter than those of CoG and CoCG land-uses,respectively.Unlike CoCG,woodlands located in Co and CoG land-use systems demonstrated a high level of agreement with self-thinning rule of−3/2.Values for the stand density index for coppiced oak woodlands were between more than 1000 for the least disturbed(Co)and less than 400 for the most disturbed woodlands(CoCG).The structure and growth rate of the coppiced oak woodlands were irreversibly disrupted by understory tillage plus grazing and in less extent by grazing alone.It was concluded that ending undergrowth cultivation in semi-arid oak coppices should be addressed as a priority by adopting minimum regulations.
基金Project supported by the National Natural Science Fundation of China(Grant No.90922007)
文摘Dynamic nonlinearities of C70/toluene solution are measured and analysed by an improved picosecond timeresolved pump-probe system based on a nonlinear imaging technique with phase object. The photophysical parameters are determined by the five-level model, which is adopted to interpret the experimental data. The change of refraction index per unit density of the excited state obtained by a numerically simulation is a critical factor to determine the nonlinear behaviour of C70 in picosecond time regime.
基金financially supported by the Special Fund for Agro-Scientific Research in the Public Interest, China (201103003)the Key Technologies R&D Program of China during the 12th Five-Year Plan period (2012BAD20B04)
文摘Understanding the relationship between the timing of N fertilizer applications and crop primary production is crucial for achieving high yield and N use efifciency in agriculture. This study investigated the effects of starting-N plus topdressing N applications (as compared to the common practice of all basal application) on soybean photosynthetic capacity under different planting densities. A ifeld experiment was conducted in two growing seasons (2011 and 2012), and the soybean (Glycine max L. Merrill) cultivar was Dongnong 52, three planting densities (20, 25 and 30 plants m-2), and four N fertilizer application patterns (all N fertilizer of 6 g N m-2 as basal fertilizer, all N fertilizer as topdressing at beginning pod stage (R3), 1.8 g N m-2 as basal fertilizer and 4.2 g N m-2 as topdressing at stage R3 and full pod stage (R4), respectively). The results indicated that under the same planting density, compared to applying all N as basal fertilizer, the application of starter-N plus topdressing N substantially reduced the rate of pod abscission, and enhanced leaf area index (LAI) signiifcantly at beginning seed stage (R5) (P〈0.05), net assimilation rate (NAR) during stages R4-full seed stage (R6) (P〈0.05), contribution rate of post-seed iflling assimilate to seed (CPA) (P〈0.05), and yield (P〈0.05). Applying topdressing N at stage R4 resulted in higher net primary production and yield than applying topdressing N at stage R3. When applying starter-N plus topdressing N at planting density of 25 plants m-2, LAI after stage R5 and NAR after stage R4 were increased by 5.92-16.3%(P〈0.05) and 13.7-26.6%(P〈0.05) with the planting density of 20 plants m-2, respectively, and yield was 8.46-14.0%(P〈0.05) higher than that under 20 plants m-2. When planting density increased to 30 plants m-2, only LAI during stages R4-R5 and NAR during stages R4-R5 increased by applying starter-N plus topdressing N, while the other indexes declined. Overall, results of this study demonstrated that applying starter-N plus topdressing N could signiifcantly enhance soybean photosynthetic capacity after stage R5 at planting density of 25 plants m-2.
文摘As Iran is located on one of the two earthquake-prone belts in the world, and existence of faults and earthquakes is normal in Iran tableland. The main reason of earthquake is Neotectonic movements which can be effective in other natural disasters such as range movements. Due to the severe shortage of historical and seismic data and device in different parts of the world, particularly Iran, need for introducing more researchers and planners of Iran to tectonics and active tectonic areas is more visible. This study is an investigation of Neotectonic activities in Khafr basin area, Fars province. To achieve the aims of this study morphometric parameters were used. Investigations showed that severity and role of tectonic activities in different parts of the basin is different, results of geomorphic and tectonic assessments indicate these differences.Stream length-gradient index (SL) on the main stream is inactive and sub streams are semi active, the ratio of the basin (BS) is 2.27, drainage basin asymmetry index (AF) is in semi active class, the ratio of width to depth of Valley (VF) shows 0.78. Indicators mentioned are in class 3 based on Iat classification, that represents tectonic activity in the area is average. Other indicators are indicative of active tectonic in the basin such as drainage density index (D) with high density, river sinuosity (S) 1.25, reverse topography symmetry Factor (T) 0.3.Generally it can be considered as moderately active region in terms of tectonic activities.
文摘The density based notion for clustering approach is used widely due to its easy implementation and ability to detect arbitrary shaped clusters in the presence of noisy data points without requiring prior knowledge of the number of clusters to be identified. Density-based spatial clustering of applications with noise (DBSCAN) is the first algorithm proposed in the literature that uses density based notion for cluster detection. Since most of the real data set, today contains feature space of adjacent nested clusters, clearly DBSCAN is not suitable to detect variable adjacent density clusters due to the use of global density parameter neighborhood radius Y,.ad and minimum number of points in neighborhood Np~,. So the efficiency of DBSCAN depends on these initial parameter settings, for DBSCAN to work properly, the neighborhood radius must be less than the distance between two clusters otherwise algorithm merges two clusters and detects them as a single cluster. Through this paper: 1) We have proposed improved version of DBSCAN algorithm to detect clusters of varying density adjacent clusters by using the concept of neighborhood difference and using the notion of density based approach without introducing much additional computational complexity to original DBSCAN algorithm. 2) We validated our experimental results using one of our authors recently proposed space density indexing (SDI) internal cluster measure to demonstrate the quality of proposed clustering method. Also our experimental results suggested that proposed method is effective in detecting variable density adjacent nested clusters.