The orchards usually have rough terrain,dense tree canopy and weeds.It is hard to use GNSS for autonomous navigation in orchard due to signal occlusion,multipath effect,and radio frequency interference.To achieve auto...The orchards usually have rough terrain,dense tree canopy and weeds.It is hard to use GNSS for autonomous navigation in orchard due to signal occlusion,multipath effect,and radio frequency interference.To achieve autonomous navigation in orchard,a visual navigation method based on multiple images at different shooting angles is proposed in this paper.A dynamic image capturing device is designed for camera installation and multiple images can be shot at different angles.Firstly,the obtained orchard images are classified into sky and soil detection stage.Each image is transformed to HSV space and initially segmented into sky,canopy and soil regions by median filtering and morphological processing.Secondly,the sky and soil regions are extracted by the maximum connected region algorithm,and the region edges are detected and filtered by the Canny operator.Thirdly,the navigation line in the current frame is extracted by fitting the region coordinate points.Then the dynamic weighted filtering algorithm is used to extract the navigation line for the soil and sky detection stage,respectively,and the navigation line for the sky detection stage is mirrored to the soil region.Finally,the Kalman filter algorithm is used to fuse and extract the final navigation path.The test results on 200 images show that the accuracy of visual navigation path fitting is 95.5%,and single frame image processing costs 60 ms,which meets the real-time and robustness requirements of navigation.The visual navigation experiments in Camellia oleifera orchard show that when the driving speed is 0.6 m/s,the maximum tracking offset of visual navigation in weed-free and weedy environments is 0.14 m and 0.24 m,respectively,and the RMSE is 30 mm and 55 mm,respectively.展开更多
The airspace congestion is becoming more and more severe.Although there are traffic flow management（TFM）initiatives based on CDM widely applied,how to reschedule these disrupted flights of different airlines integra...The airspace congestion is becoming more and more severe.Although there are traffic flow management（TFM）initiatives based on CDM widely applied,how to reschedule these disrupted flights of different airlines integrating TFM initiatives and allocate the limited airspace resources to these airlines equitably and efficiently is still a problem.The air traffic management（ATM）authority aims to minimizing the systemic costs of congested airspaces.And the airlines are self-interested and profit-oriented.Being incorporated into the collaborative decision making（CDM）process,the airlines can influence the rescheduling decisions to profit themselves.The airlines maybe hide the flight information that is disadvantageous to them,but is necessary to the optimal system decision.To realize the coincidence goal between the ATM authority and airlines for the efficient,and equitable allocation of airspace resources,this paper provides an auction-based market method to solve the congestion airspace problem under the pre-tactic and tactic stage of air traffic flow management.Through a simulation experiment,the rationing results show that the auction method can decrease the total delay costs of flights in the congested airspace compared with both the first schedule first service（FSFS）tactic and the ration by schedule（RBS）tactic.Finally,the analysis results indicate that if reallocate the charges from the auction to the airlines according to the proportion of their disrupted flights,the auction mechanism can allocate the airspace resource in economy equitably and decrease the delay losses of the airlines compared with the results of the FSFS tactic.展开更多
In the pump-controlled motor hydraulic transmission system,when the pressure pulsation frequencies seperately generated by the pump and the motor are close to each other,the hydraulic system will generate a strong pre...In the pump-controlled motor hydraulic transmission system,when the pressure pulsation frequencies seperately generated by the pump and the motor are close to each other,the hydraulic system will generate a strong pressure beat vibration phenomenon,which will seriously affect the smooth running of the hydraulic system.However,the modulated pressure signal also carries information related to the operating state of the hydraulic system,and a accurate extraction of pressure vibration characteristics is the key to obtain the operating state information of the hydraulic system.In order to extract the pressure beat vibration signal component effectively from the multi-component time-varying aliasing pressure signal and reconstruct the time domain characteristics,an extraction method of the pressure beat vibration characteristics of the hydraulic transmission system based on variational mode decomposition(VMD)is proposed.The experimental results show that the VMD method can accurately extract the pressure beat vibration characteristics from the high-pressure oil pressure signal of the hydraulic system,and the extraction effect is preferable to that of the traditional signal processing methods such as empirical mode decomposition(EMD).展开更多
At 5:39 am on June 24, 2017, a landslide occurred in the village of Xinmo in Maoxian County, Aba Tibet and Qiang Autonomous Prefecture(Sichuan Province, Southwest China). On June 25, aerial images were acquired from a...At 5:39 am on June 24, 2017, a landslide occurred in the village of Xinmo in Maoxian County, Aba Tibet and Qiang Autonomous Prefecture(Sichuan Province, Southwest China). On June 25, aerial images were acquired from an unmanned aerial vehicle(UAV), and a digital elevation model(DEM) was processed. Landslide geometrical features were then analyzed. These are the front and rear edge elevation, accumulation area and horizontal sliding distance. Then, the volume and the spatial distribution of the thickness of the deposit were calculated from the difference between the DEM available before the landslide, and the UAV-derived DEM collected after the landslide. Also, the disaster was assessed using high-resolution satellite images acquired before the landslide. These include Quick Bird, Pleiades-1 and GF-2 images with spatial resolutions of 0.65 m, 0.70 m, and 0.80 m, respectively, and the aerial images acquired from the UAV after the landslide with a spatial resolution of 0.1 m. According to the analysis, the area of the landslide was 1.62 km2, and the volume of the landslide was 7.70 ± 1.46 million m3. The average thickness of the landslide accumulation was approximately 8 m. The landslide destroyed a total of 103 buildings. The area of destroyed farmlands was 2.53 ha, and the orchard area was reduced by 28.67 ha. A 2-km section of Songpinggou River was blocked and a 2.1-km section of township road No. 104 was buried. Constrained by the terrain conditions, densely populated and more economically developed areas in the upper reaches of the Minjiang River basin are mainly located in the bottom of the valleys. This is a dangerous area regarding landslide, debris flow and flash flood events Therefore, in mountainous, high-risk disaster areas, it is important to carefully select residential sites to avoid a large number of casualties.展开更多
This paper points out that the mineral rights should be transferred at the mineral resource’s own value after the analysis that the resource owner can not recover the resource’s value only by collecting the mineral ...This paper points out that the mineral rights should be transferred at the mineral resource’s own value after the analysis that the resource owner can not recover the resource’s value only by collecting the mineral resource tax and the mineral resource compensating fee.Then the paper expounds the theory on mineral resource evaluation and gives out tbe income evaluating model. The paper finally concludes that the mineral rights should be transferred by the manner of auction after the analysis on the requirements asked by the economics on the mineral rights-transferring.展开更多
This paper deals with the security voting structure in an auction mechanism used to sell an item Of high-tech. The design of security voting structure allows the seller to choose between two objectives that are not mu...This paper deals with the security voting structure in an auction mechanism used to sell an item Of high-tech. The design of security voting structure allows the seller to choose between two objectives that are not mutually consistent. However, if the seller wants to maximize his revenue, he should retain some shares to benefit from the future dividends generated by the acquirer. In addition, if he wants to sell his high-tech to the most efficient candidate, he should sell all the shares.展开更多
We evaluated how historical storm events have shaped the current forest landscape in three Pyrenean subalpine forests(NE Spain).For this purpose we related forest damage estimations obtained from multi-temporal aerial...We evaluated how historical storm events have shaped the current forest landscape in three Pyrenean subalpine forests(NE Spain).For this purpose we related forest damage estimations obtained from multi-temporal aerial photographic comparisons to the current forest typology generated from airborne Li DAR data, and we examined the role of past natural disturbance on the current spatial distribution of forest structural types.We found six forest structural types in the landscape: early regeneration(T1 and T2), young even-aged stands(T3), uneven-aged stands(T4) and adult stands(T5and T6).All of the types were related to the timing and severity of past storms, with early-regeneration structures being found in areas markedly affected in recent times, and adult stands predominating in those areas that had suffered lowest damage levels within the study period.In general, landscapes where high or medium levels of damage were recurrent also presented higher levels of spatial heterogeneity,whereas the opposite pattern was found in the less markedly affected landscape, characterized by thepresence of large regular patches.Our results show the critical role that storm regimes in terms of timing and severity of past storms can play in shaping current forest structure and future dynamics in subalpine forests.The knowledge gained could be used to help define alternative forest management strategies oriented toward the enhancement of landscape heterogeneity as a measure to face future environmental uncertainty.展开更多
Bulletproof steel plates are widely used for the safety of special vehicles.This paper mainly researches on the shoot resistance of heat treated light weight B-grade bulletproof steel plates through numerical analysis...Bulletproof steel plates are widely used for the safety of special vehicles.This paper mainly researches on the shoot resistance of heat treated light weight B-grade bulletproof steel plates through numerical analysis.Based on the flow behavior of bulletproof steel plates and bullet at various high strain rates,finite element(FE) model has been set up using ANSYS/LS-DYNA software.The simulation results are compared with the shooting results,which show a good consistency and a high reliability.Therefore,the simulation results are efficient approaches and strategies to decide and select the mechanical property and thickness of bulletproof steel plates,saving a lot of work and the cost of experiments.展开更多
Basketball shooting technique is the core technology. The shooting angle, basket entering angle, ball＇s rotation, aiming at point, exerting strength cooperatively with the whole body, and flicking the ball using inde...Basketball shooting technique is the core technology. The shooting angle, basket entering angle, ball＇s rotation, aiming at point, exerting strength cooperatively with the whole body, and flicking the ball using index finger before it leaves from hand are the important factors to decide if the shooting techniques are reasonable and the successful shooting rate is high or not. In this paper, the theory of biomechanics is analyzed around basketball spin on the role of shooting, shooting aiming point selection diversity, difference and its impact on investment and basketball shooting rate.展开更多
Innervated full thickness graft will be presented as an option to reconstruct a fingertip defect which might result in better sensibility than standard reconstruction using a full thickness graft without innervation. ...Innervated full thickness graft will be presented as an option to reconstruct a fingertip defect which might result in better sensibility than standard reconstruction using a full thickness graft without innervation. Also, anastomosing the nerve stumps can decrease the chance of developing neuroma.展开更多
Recently, an experimentally feasible three-party quantum sealed-bid auction protocol based on EPR pairs [Z.Y. Wang, Commun. Theor. Phys. 54 （2010） 997] was proposed. However, this study points out Wang＇s protocol c...Recently, an experimentally feasible three-party quantum sealed-bid auction protocol based on EPR pairs [Z.Y. Wang, Commun. Theor. Phys. 54 （2010） 997] was proposed. However, this study points out Wang＇s protocol cannot resist some internal bidders＇ attacks, such as the Twiee-CNOT attack, the collusion attack. A malicious bidder can launch the Twice-CNOT attack to obtain the other＇s bid, or the dishonest auctioneer may collude with one bidder and help him/her win the action by changing his/her bid. For preventing against these attacks, a simple solution by using the QKD-based message encryption and a post-confirmation mechanism by adopting the hash function are proposed.展开更多
Purpose： To compare the efficacy of quadratus femoris muscle pedicle bone flap transplantation combined with hollow compression screw fixation versus AO hollow compression screw fixation in the treatment of femoral n...Purpose： To compare the efficacy of quadratus femoris muscle pedicle bone flap transplantation combined with hollow compression screw fixation versus AO hollow compression screw fixation in the treatment of femoral neck fracture for Chinese young and middle-aged patients. Methods： Case-controlled studies （CCTs） were used to compare the two operative methods in the treatment of femoral neck fractures. Data were retrieved from the Cochrane Library, Pubmed Database, CNKI, Chinese Biomedical Database. Wanfang Data published during the period of January 2005 to December 2014. Methodological quality of the trials was critically assessed, and relevant data were extracted. Statistical Software Revman S.0 was used for data-analysis. Results： Eight articles were included in the meta-analysis. The results showed that there was statistical significance in the rate of fracture healing [OR = 5.43, 95% CI （2.89, 10.20）, p 〈 0.05], the rate of good function of hip joint [OR=5.12, 95% CI （3.21, 8.17）, p 〈 0.05], the rate of femoral head necrosis [OR = 4.21, 95% CI （2.02, 8.76）, p 〈 0.05], the time of fracture healing [WMD = -46.85, 95% CI （-65.13, -28.56）, p 〈 0.05] between the two groups. Conclusions： For the treatment of femoral neck fractures, the transplantation of quadratus femoris muscle pedicle bone flap combined with hollow compression screw; fixation is superior to the AO hollow compression screw fixation in terms of the rate; of fracture healing, the rate of good function of hip joint, the rate of femoral head： necrosis and the time of fracture healing.展开更多
基金National Key Research and Development Program of China(2022YFD2202103)National Natural Science Foundation of China(31971798)+2 种基金Zhejiang Provincial Key Research&Development Plan(2023C02049、2023C02053)SNJF Science and Technology Collaborative Program of Zhejiang Province(2022SNJF017)Hangzhou Agricultural and Social Development Research Project(202203A03)。
文摘The orchards usually have rough terrain,dense tree canopy and weeds.It is hard to use GNSS for autonomous navigation in orchard due to signal occlusion,multipath effect,and radio frequency interference.To achieve autonomous navigation in orchard,a visual navigation method based on multiple images at different shooting angles is proposed in this paper.A dynamic image capturing device is designed for camera installation and multiple images can be shot at different angles.Firstly,the obtained orchard images are classified into sky and soil detection stage.Each image is transformed to HSV space and initially segmented into sky,canopy and soil regions by median filtering and morphological processing.Secondly,the sky and soil regions are extracted by the maximum connected region algorithm,and the region edges are detected and filtered by the Canny operator.Thirdly,the navigation line in the current frame is extracted by fitting the region coordinate points.Then the dynamic weighted filtering algorithm is used to extract the navigation line for the soil and sky detection stage,respectively,and the navigation line for the sky detection stage is mirrored to the soil region.Finally,the Kalman filter algorithm is used to fuse and extract the final navigation path.The test results on 200 images show that the accuracy of visual navigation path fitting is 95.5%,and single frame image processing costs 60 ms,which meets the real-time and robustness requirements of navigation.The visual navigation experiments in Camellia oleifera orchard show that when the driving speed is 0.6 m/s,the maximum tracking offset of visual navigation in weed-free and weedy environments is 0.14 m and 0.24 m,respectively,and the RMSE is 30 mm and 55 mm,respectively.
基金Supported by the National High Technology Research and Development Program of China("863"Program)(20060AA12A105)the Chinese Airspace Management Commission Researching Program(GKG200802006)~~
文摘The airspace congestion is becoming more and more severe.Although there are traffic flow management（TFM）initiatives based on CDM widely applied,how to reschedule these disrupted flights of different airlines integrating TFM initiatives and allocate the limited airspace resources to these airlines equitably and efficiently is still a problem.The air traffic management（ATM）authority aims to minimizing the systemic costs of congested airspaces.And the airlines are self-interested and profit-oriented.Being incorporated into the collaborative decision making（CDM）process,the airlines can influence the rescheduling decisions to profit themselves.The airlines maybe hide the flight information that is disadvantageous to them,but is necessary to the optimal system decision.To realize the coincidence goal between the ATM authority and airlines for the efficient,and equitable allocation of airspace resources,this paper provides an auction-based market method to solve the congestion airspace problem under the pre-tactic and tactic stage of air traffic flow management.Through a simulation experiment,the rationing results show that the auction method can decrease the total delay costs of flights in the congested airspace compared with both the first schedule first service（FSFS）tactic and the ration by schedule（RBS）tactic.Finally,the analysis results indicate that if reallocate the charges from the auction to the airlines according to the proportion of their disrupted flights,the auction mechanism can allocate the airspace resource in economy equitably and decrease the delay losses of the airlines compared with the results of the FSFS tactic.
基金National Natural Science Foundation of China(No.51675399)。
文摘In the pump-controlled motor hydraulic transmission system,when the pressure pulsation frequencies seperately generated by the pump and the motor are close to each other,the hydraulic system will generate a strong pressure beat vibration phenomenon,which will seriously affect the smooth running of the hydraulic system.However,the modulated pressure signal also carries information related to the operating state of the hydraulic system,and a accurate extraction of pressure vibration characteristics is the key to obtain the operating state information of the hydraulic system.In order to extract the pressure beat vibration signal component effectively from the multi-component time-varying aliasing pressure signal and reconstruct the time domain characteristics,an extraction method of the pressure beat vibration characteristics of the hydraulic transmission system based on variational mode decomposition(VMD)is proposed.The experimental results show that the VMD method can accurately extract the pressure beat vibration characteristics from the high-pressure oil pressure signal of the hydraulic system,and the extraction effect is preferable to that of the traditional signal processing methods such as empirical mode decomposition(EMD).
基金funded by the National Key Technologies R&D Program of China (Grants No. 2017YFC0505104)the Key Laboratory of Digital Mapping and Land Information Application of National Administration of Surveying, Mapping and Geoinformation of China (Grants No. DM2016SC09)
文摘At 5:39 am on June 24, 2017, a landslide occurred in the village of Xinmo in Maoxian County, Aba Tibet and Qiang Autonomous Prefecture(Sichuan Province, Southwest China). On June 25, aerial images were acquired from an unmanned aerial vehicle(UAV), and a digital elevation model(DEM) was processed. Landslide geometrical features were then analyzed. These are the front and rear edge elevation, accumulation area and horizontal sliding distance. Then, the volume and the spatial distribution of the thickness of the deposit were calculated from the difference between the DEM available before the landslide, and the UAV-derived DEM collected after the landslide. Also, the disaster was assessed using high-resolution satellite images acquired before the landslide. These include Quick Bird, Pleiades-1 and GF-2 images with spatial resolutions of 0.65 m, 0.70 m, and 0.80 m, respectively, and the aerial images acquired from the UAV after the landslide with a spatial resolution of 0.1 m. According to the analysis, the area of the landslide was 1.62 km2, and the volume of the landslide was 7.70 ± 1.46 million m3. The average thickness of the landslide accumulation was approximately 8 m. The landslide destroyed a total of 103 buildings. The area of destroyed farmlands was 2.53 ha, and the orchard area was reduced by 28.67 ha. A 2-km section of Songpinggou River was blocked and a 2.1-km section of township road No. 104 was buried. Constrained by the terrain conditions, densely populated and more economically developed areas in the upper reaches of the Minjiang River basin are mainly located in the bottom of the valleys. This is a dangerous area regarding landslide, debris flow and flash flood events Therefore, in mountainous, high-risk disaster areas, it is important to carefully select residential sites to avoid a large number of casualties.
文摘This paper points out that the mineral rights should be transferred at the mineral resource’s own value after the analysis that the resource owner can not recover the resource’s value only by collecting the mineral resource tax and the mineral resource compensating fee.Then the paper expounds the theory on mineral resource evaluation and gives out tbe income evaluating model. The paper finally concludes that the mineral rights should be transferred by the manner of auction after the analysis on the requirements asked by the economics on the mineral rights-transferring.
文摘This paper deals with the security voting structure in an auction mechanism used to sell an item Of high-tech. The design of security voting structure allows the seller to choose between two objectives that are not mutually consistent. However, if the seller wants to maximize his revenue, he should retain some shares to benefit from the future dividends generated by the acquirer. In addition, if he wants to sell his high-tech to the most efficient candidate, he should sell all the shares.
基金Financial support for this study was provided by the Spanish Ministry of Economy and Competitiveness through the project RESILFOR(AGL2012-40039-C02-01)LC and JRGO were both supported by Ramón y Cajal contracts(RYC-2009-04985 and RYC-2011-08983)
文摘We evaluated how historical storm events have shaped the current forest landscape in three Pyrenean subalpine forests(NE Spain).For this purpose we related forest damage estimations obtained from multi-temporal aerial photographic comparisons to the current forest typology generated from airborne Li DAR data, and we examined the role of past natural disturbance on the current spatial distribution of forest structural types.We found six forest structural types in the landscape: early regeneration(T1 and T2), young even-aged stands(T3), uneven-aged stands(T4) and adult stands(T5and T6).All of the types were related to the timing and severity of past storms, with early-regeneration structures being found in areas markedly affected in recent times, and adult stands predominating in those areas that had suffered lowest damage levels within the study period.In general, landscapes where high or medium levels of damage were recurrent also presented higher levels of spatial heterogeneity,whereas the opposite pattern was found in the less markedly affected landscape, characterized by thepresence of large regular patches.Our results show the critical role that storm regimes in terms of timing and severity of past storms can play in shaping current forest structure and future dynamics in subalpine forests.The knowledge gained could be used to help define alternative forest management strategies oriented toward the enhancement of landscape heterogeneity as a measure to face future environmental uncertainty.
文摘Bulletproof steel plates are widely used for the safety of special vehicles.This paper mainly researches on the shoot resistance of heat treated light weight B-grade bulletproof steel plates through numerical analysis.Based on the flow behavior of bulletproof steel plates and bullet at various high strain rates,finite element(FE) model has been set up using ANSYS/LS-DYNA software.The simulation results are compared with the shooting results,which show a good consistency and a high reliability.Therefore,the simulation results are efficient approaches and strategies to decide and select the mechanical property and thickness of bulletproof steel plates,saving a lot of work and the cost of experiments.
文摘Basketball shooting technique is the core technology. The shooting angle, basket entering angle, ball＇s rotation, aiming at point, exerting strength cooperatively with the whole body, and flicking the ball using index finger before it leaves from hand are the important factors to decide if the shooting techniques are reasonable and the successful shooting rate is high or not. In this paper, the theory of biomechanics is analyzed around basketball spin on the role of shooting, shooting aiming point selection diversity, difference and its impact on investment and basketball shooting rate.
文摘Innervated full thickness graft will be presented as an option to reconstruct a fingertip defect which might result in better sensibility than standard reconstruction using a full thickness graft without innervation. Also, anastomosing the nerve stumps can decrease the chance of developing neuroma.
基金Supported by the National Natural Science Foundation of China under Grant Nos.61103235,61170321,and 61373131the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)+1 种基金the Natural Science Foundation of Jiangsu Province,China(BK2010570)State Key Laboratory of Software Engineering,Wuhan University(SKLSE2012-09-41)
文摘Recently, an experimentally feasible three-party quantum sealed-bid auction protocol based on EPR pairs [Z.Y. Wang, Commun. Theor. Phys. 54 （2010） 997] was proposed. However, this study points out Wang＇s protocol cannot resist some internal bidders＇ attacks, such as the Twiee-CNOT attack, the collusion attack. A malicious bidder can launch the Twice-CNOT attack to obtain the other＇s bid, or the dishonest auctioneer may collude with one bidder and help him/her win the action by changing his/her bid. For preventing against these attacks, a simple solution by using the QKD-based message encryption and a post-confirmation mechanism by adopting the hash function are proposed.
基金National Natural Science Foundation of China （81572098） Natural Science Foundation of Shanxi Province of China （2008012011-3, 201701D121161）.
文摘Purpose： To compare the efficacy of quadratus femoris muscle pedicle bone flap transplantation combined with hollow compression screw fixation versus AO hollow compression screw fixation in the treatment of femoral neck fracture for Chinese young and middle-aged patients. Methods： Case-controlled studies （CCTs） were used to compare the two operative methods in the treatment of femoral neck fractures. Data were retrieved from the Cochrane Library, Pubmed Database, CNKI, Chinese Biomedical Database. Wanfang Data published during the period of January 2005 to December 2014. Methodological quality of the trials was critically assessed, and relevant data were extracted. Statistical Software Revman S.0 was used for data-analysis. Results： Eight articles were included in the meta-analysis. The results showed that there was statistical significance in the rate of fracture healing [OR = 5.43, 95% CI （2.89, 10.20）, p 〈 0.05], the rate of good function of hip joint [OR=5.12, 95% CI （3.21, 8.17）, p 〈 0.05], the rate of femoral head necrosis [OR = 4.21, 95% CI （2.02, 8.76）, p 〈 0.05], the time of fracture healing [WMD = -46.85, 95% CI （-65.13, -28.56）, p 〈 0.05] between the two groups. Conclusions： For the treatment of femoral neck fractures, the transplantation of quadratus femoris muscle pedicle bone flap combined with hollow compression screw; fixation is superior to the AO hollow compression screw fixation in terms of the rate; of fracture healing, the rate of good function of hip joint, the rate of femoral head： necrosis and the time of fracture healing.
