UAV cooperative control has been applied in many complex UAV communication networks. It remains challenging to develop UAV cooperative coverage and UAV energy-efficient communication technology. In this paper, we inve...UAV cooperative control has been applied in many complex UAV communication networks. It remains challenging to develop UAV cooperative coverage and UAV energy-efficient communication technology. In this paper, we investigate current works about UAV coverage problem and propose a multi-UAV coverage model based on energy-efficient communication. The proposed model is decomposed into two steps: coverage maximization and power control, both are proved to be exact potential games(EPG) and have Nash equilibrium(NE) points. Then the multi-UAV energy-efficient coverage deployment algorithm based on spatial adaptive play(MUECD-SAP) is adopted to perform coverage maximization and power control, which guarantees optimal energy-efficient coverage deployment. Finally, simulation results show the effectiveness of our proposed approach, and confirm the reliability of proposed model.展开更多
The stratospheric quasi-zero wind layer (QZWL) is a transition region with low zonal wind speeds in the lower stratosphere at an altitude of ~20 km. The zonal wind direction above the QZWL layer is opposite to that be...The stratospheric quasi-zero wind layer (QZWL) is a transition region with low zonal wind speeds in the lower stratosphere at an altitude of ~20 km. The zonal wind direction above the QZWL layer is opposite to that below the QZWL layer and the north –south wind component is small. The atmospheric wind field near the stratospheric QZWL is an important factor affecting the flight altitude and dynamic control of stratospheric airships. It is therefore necessary to study the stratospheric QZWL to provide better environmental information for these aircraft. High-resolution radiosonde data were used to analyze the characteristics of the stratospheric QZWL over Korla, Xinjiang Province, China. A weak wind layer in which the wind direction suddenly reversed from westerly to easterly was observed at ~20 km in the lower stratosphere, characteristic of the stratospheric QZWL. The Weather Research and Forecasting model was used to simulate the profiles of the horizontal wind speed and direction over Korla. The forcing effect of each diagnostic term in the equation on the zonal wind speed was analyzed. The results showed that the advection term was the dominant factor forcing the zonal wind speed. The wave term had a secondary forcing role, although the forcing effect of the wave term on the zonal wind speed was significant in some regions.展开更多
This paper investigates the channel diversity problem in high frequency(HF) communication systems. Due to the limited HF spectrum resources, a HF communication system with shared channels is considered, where each use...This paper investigates the channel diversity problem in high frequency(HF) communication systems. Due to the limited HF spectrum resources, a HF communication system with shared channels is considered, where each user equipment(UE) has individual communication demand. In order to maximize the communication probability of the whole system, a matching-potential game framework is designed. In detail, the channel diversity problem is decomposed into two sub-problems. One is channel-transmitter matching problem, which can be formulated as a many-to-one matching game. The other is the transmitter allocation problem which decides the transmission object that each transmitter communicates with under channel-transmitter matching result, and this sub-problem can be modeled as a potential game. A multiple round stable matching algorithm(MRSMA) is proposed, which obtains a stable matching result for the first sub-problem, and a distributed BR-based transmitter allocation algorithm(DBRTAA) is designed to reach Nash Equilibrium(NE) of the second sub-problem. Simulation results verify the effectiveness and superiority of the proposed method.展开更多
Boreal summer intraseasonal oscillation(BSISO) of lower tropospheric ozone is observed in the Indian summer monsoon(ISM) region on the basis of ERA-Interim reanalysis data and ozonesonde data from the World Ozone and ...Boreal summer intraseasonal oscillation(BSISO) of lower tropospheric ozone is observed in the Indian summer monsoon(ISM) region on the basis of ERA-Interim reanalysis data and ozonesonde data from the World Ozone and Ultraviolet Radiation Data Centre. The 30–60-day intraseasonal variation of lower-tropospheric ozone shows a northwest–southeast pattern with northeastward propagation in the ISM region. The most significant ozone variations are observed in the Maritime Continent and western North Pacific. In the tropics, ozone anomalies extend from the surface to 300 hPa; however, in extratropical areas, it is mainly observed under 500 hPa. Precipitation caused by BSISO plays a dominant role in modulating the BSISO of lower-tropospheric ozone in the tropics, causing negative/positive ozone anomalies in phases 1–3/5–6. As the BSISO propagates northeastward to the western North Pacific, horizontal transport becomes relatively more important, increasing/reducing tropospheric ozone via anticyclonic/cyclonic anomalies over the western North Pacific in phases 3–4/7–8.As two extreme conditions of the ISM, most of its active/break events occur in BSISO phases 4–7/1–8 when suppressed/enhanced convection appears over the equatorial eastern Indian Ocean and enhanced/suppressed convection appears over India, the Bay of Bengal, and the South China Sea. As a result, the BSISO of tropospheric ozone shows significant positive/negative anomalies over the Maritime Continent, as well as negative/positive anomalies over India, the Bay of Bengal,and the South China Sea in active/break spells of the ISM. This BSISO of tropospheric ozone is more remarkable in break spells than in active spells of the ISM, due to the stronger amplitude of BSISO in the former.展开更多
We present characterizations of the dynamic turbulence in the lower stratosphere measured by a new balloon-based system designed for detecting finer scale dynamic turbulence. The balloon-based system included a consta...We present characterizations of the dynamic turbulence in the lower stratosphere measured by a new balloon-based system designed for detecting finer scale dynamic turbulence. The balloon-based system included a constant temperature anemometer(CTA) operating at a sampling rate of 2 k Hz at an ascent speed of 5 m s^(-1)(corresponding to a vertical resolution of 2.5 mm), an industrial personal computer, batteries, sensors for ambient temperature and humidity, an A/D converter, and others. The system was successfully launched to 24 km altitude over Bayannur City, Inner Mongolia Province. Results show the spatial intermittence of the turbulence layers, with clear boundaries between turbulent and nonturbulent regions. This is the first time that the dynamic turbulence spectrum down to the viscous sub-range has been obtained throughout the lower stratosphere over China. With that, the energy dissipation rates of dynamic turbulence could be calculated with high precision. The profile of the dissipation rates varied from 7.37 × 10^(-7) to 4.23 W kg^(-1) and increased with altitude in the stratosphere.展开更多
As the strongest subseasonal atmospheric variability during boreal winter, three remarkable sudden stratospheric major warming(SSW) events in the 2000 s are investigated in terms of the Brewer–Dobson circulation(BDC)...As the strongest subseasonal atmospheric variability during boreal winter, three remarkable sudden stratospheric major warming(SSW) events in the 2000 s are investigated in terms of the Brewer–Dobson circulation(BDC) response. Our study shows that the changes of cross-isentropic velocity during the SSWs are not only confined to the polar region, but also extend to the whole Northern Hemisphere: enhanced descent in the polar region, as well as enhanced ascent in the tropics. When the acceleration of the deep branch of the BDC descends to the middle stratosphere, its strength rapidly decreases over a period of one to two weeks. The acceleration of the deep branch of the BDC is driven by the enhanced planetary wave activity in the mid-to-high-latitude stratosphere. Different from the rapid response of the deep branch of the BDC, tropical upwelling in the lower stratosphere accelerates up to 20%–40% compared with the climatology, 20–30 days after the onset of the SSWs,and the acceleration lasts for one to three months. The enhancement of tropical upwelling is associated with the large-scale wave-breaking in the subtropics interacting with the midlatitude and tropical Quasi-Biennial Oscillation–related mean flow.展开更多
The balloon-borne Aircore campaign was conducted in Inner Mongolia,China,on June 13 and 142018,which detected carbon dioxide(CO2)and carbon monoxide(CO)profiles from surface to 24 km,showing strong positive and negati...The balloon-borne Aircore campaign was conducted in Inner Mongolia,China,on June 13 and 142018,which detected carbon dioxide(CO2)and carbon monoxide(CO)profiles from surface to 24 km,showing strong positive and negative correlations between 8 km and 10 km on 13 and 14 June,respectively.Backward trajectories,meteorological analyses,and CO2 horizontal distributions were combined to interpret this phenomenon.The results indicated that the source region experienced a stratospheric intrusion and exhibited a large horizontal CO2 gradient;namely,lower CO concentrations corresponded to higher CO2 concentrations and vice versa.The laminar structure with multiple origins resulted in the highly negative correlation between CO2 and CO in the upper troposphere on 14 June.The contribution of stratospheric air mass to the upper troposphere and that of tropospheric air mass to the lower stratosphere were 26.7%and24.3%,respectively,based on a mass balance approach.Another interesting phenomenon is that CO2 and CO concentrations increased substantially at approximately 8 km on 13 June.An analysis based on the backward trajectory implied that the air mass possibly came from anthropogenic sources.The slope of CO2/CO representing the anthropogenic sources was 87.3 ppm ppm-1.In addition,the CO2 profile showed that there was a large CO2 gradient of 4 ppm km-1 within the boundary layer on 13 June,and this gradient disappeared on 14 June.展开更多
The safety of transgenic technology is a major obstacle in the popularization and use of transgenic silkworms and their products.In sericulture,only the first filial generation(F1)hybrid eggs produced by cross-breedin...The safety of transgenic technology is a major obstacle in the popularization and use of transgenic silkworms and their products.In sericulture,only the first filial generation(F1)hybrid eggs produced by cross-breeding Japanese and Chinese original strains are usually used for the large-scale breeding of silkworms,but this may result in uncontrolled transgene dispersal during the popularization and application of the F1 hybrid transgenic eggs.To address this issue,we developed a safe and efficient strategy using the GAL4/Upstream activating sequence(UAS)system,the FLP/flippase recognition target(FRT)system,and the gonad-specific expression gene promoters(RSHP1p and Nanosp)for the germ cell-specific automatic excision of foreign DNA in the F1 hybrid transgenic silkworms.We established 2 types of activator strains,R1p::GAL4-Gr and Nsp::GAL4-Gr,containing the testis-specific GAL4 gene expression cassettes driven by RSHP1p or Nanosp,respectively,and 1 type of effector strain,UAS::FLP-Rg,containing the UAS-linked FLP gene expression cassette.The FLP recombinase-mediated sperm-specific complete excision of FRT-flanked target DNA in the F1 double-transgenic silkworms resulting from the hybridization of R1p::GAL4-Gr and UAS::FLP-Rg was 100%,whereas the complete excision efficiency resulting from the hybridization of Nsp::GAL4-Gr and UAS::FLP-Rg ranged from 13.73%to 80.3%.Additionally,we identified a gene,sw11114,that is expressed in both testis and ovary of Bombyx mori,and can be used to establish novel gonad-specific expression systems in transgenic silkworms.This strategy has the potential to fundamentally solve the safety issue in the production of F1 transgenic silkworm eggs and provides an important reference for the safety of transgenic technology in other insect species.展开更多
With e-commerce concentrating retailers and customers onto one platform,logistics companies(e.g.,JD Logistics)have launched integrated supply chain solutions for corporate customers(e.g.,online retailers)with warehous...With e-commerce concentrating retailers and customers onto one platform,logistics companies(e.g.,JD Logistics)have launched integrated supply chain solutions for corporate customers(e.g.,online retailers)with warehousing,transportation,last-mile delivery,and other value-added services.The platform’s concentration of business flows leads to the consolidation of logistics resources,which allows us to coordinate supply chain operations across different corporate customers.This paper studies the stochastic joint replenishment problem of coordinating multiple suppliers and multiple products to gain the economies of scale of the replenishment setup cost and the warehouse inbound operational cost.To this end,we develop stochastic joint replenishment models based on the general-integer policy(SJRM-GIP)for the multi-supplier and multi-product problems and further reformulate the resulted nonlinear optimization models into equivalent mixed integer second-order conic programs(MISOCPs)when the inbound operational cost takes the square-root form.Then,we propose generalized Benders decomposition(GBD)algorithms to solve the MISOCPs by exploiting the Lagrangian duality,convexity,and submodularity of the sub-problems.To reduce the computational burden of the SJRM-GIP,we further propose an SJRM based on the power-of-two policy and extend the proposed GBD algorithms.Extensive numerical experiments based on practical datasets show that the stochastic joint replenishment across multiple suppliers and multiple products would deliver 13∼20%cost savings compared to the independent replenishment benchmark,and on average the proposed GBD algorithm based on the enhanced gradient cut can achieve more than 90%computational time reduction for large-size problem instances compared to the Gurobi solver.The power-of-two policy is capable of providing high-quality solutions with high computational efficiency.展开更多
Logistics networks (LNs) are essential for the transportation and distribution of goods or services from suppliers to consumers. However, LNs with complex structures are more vulnerable to disruptions due to natural d...Logistics networks (LNs) are essential for the transportation and distribution of goods or services from suppliers to consumers. However, LNs with complex structures are more vulnerable to disruptions due to natural disasters and accidents. To address the LN post-disruption response strategy optimization problem, this study proposes a novel two-stage stochastic programming model with robust delivery time constraints. The proposed model jointly optimizes the new-line-opening and rerouting decisions in the face of uncertain transport demands and transportation times. To enhance the robustness of the response strategy obtained, the conditional value at risk (CVaR) criterion is utilized to reduce the operational risk, and robust constraints based on the scenario-based uncertainty sets are proposed to guarantee the delivery time requirement. An equivalent tractable mixed-integer linear programming reformulation is further derived by linearizing the CVaR objective function and dualizing the infinite number of robust constraints into finite ones. A case study based on the practical operations of the JD LN is conducted to validate the practical significance of the proposed model. A comparison with the rerouting strategy and two benchmark models demonstrates the superiority of the proposed model in terms of operational cost, delivery time, and loading rate.展开更多
Using NCEP/NCAR reanalysis data, we investigate the statistical characteristics and the long-term variations of major sudden stratospheric warming(SSW) events in the Northern Hemisphere. We find that the strength and ...Using NCEP/NCAR reanalysis data, we investigate the statistical characteristics and the long-term variations of major sudden stratospheric warming(SSW) events in the Northern Hemisphere. We find that the strength and duration of major SSW events have increased from 1958 to 2019 because of the strengthening of winter planetary wave activity. The frequency of the SSW events related to displacement or split of the polar vortex differs between early,middle, and late winter. Early(middle) winter is dominated by displacement(split) SSW events, while late winter sees almost equal frequency of these two types of events. This is due to the differences in the relative strength of wavenumber-1 and wavenumber-2 planetary wave activity among the three winter periods. As a result of the increase in upward planetary wave activity and the decrease in westerly winds around the polar vortex in middle winter, more SSW events tend to occur in middle winter. In addition, we reveal the influence of the downward propagation of different types of SSW events on the surface temperature anomaly. Compared with early displacement SSW events, middle split SSW events are followed by more surface cold centers in Russia, northern China, and North America.展开更多
基金supported by the National Natural Science Foundation of China under Grant No. 61771488in part by the Natural Science Foundation for Distinguished Young Scholars of Jiangsu Province under Grant No. BK20160034+1 种基金 in part by the Open Research Foundation of Science and Technology on Communication Networks Laboratorythe Guang Xi Universities Key Laboratory Fund of Embedded Technology and Intelligent System (Guilin University of Technology)
文摘UAV cooperative control has been applied in many complex UAV communication networks. It remains challenging to develop UAV cooperative coverage and UAV energy-efficient communication technology. In this paper, we investigate current works about UAV coverage problem and propose a multi-UAV coverage model based on energy-efficient communication. The proposed model is decomposed into two steps: coverage maximization and power control, both are proved to be exact potential games(EPG) and have Nash equilibrium(NE) points. Then the multi-UAV energy-efficient coverage deployment algorithm based on spatial adaptive play(MUECD-SAP) is adopted to perform coverage maximization and power control, which guarantees optimal energy-efficient coverage deployment. Finally, simulation results show the effectiveness of our proposed approach, and confirm the reliability of proposed model.
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences (Grant No. XDA17010105)
文摘The stratospheric quasi-zero wind layer (QZWL) is a transition region with low zonal wind speeds in the lower stratosphere at an altitude of ~20 km. The zonal wind direction above the QZWL layer is opposite to that below the QZWL layer and the north –south wind component is small. The atmospheric wind field near the stratospheric QZWL is an important factor affecting the flight altitude and dynamic control of stratospheric airships. It is therefore necessary to study the stratospheric QZWL to provide better environmental information for these aircraft. High-resolution radiosonde data were used to analyze the characteristics of the stratospheric QZWL over Korla, Xinjiang Province, China. A weak wind layer in which the wind direction suddenly reversed from westerly to easterly was observed at ~20 km in the lower stratosphere, characteristic of the stratospheric QZWL. The Weather Research and Forecasting model was used to simulate the profiles of the horizontal wind speed and direction over Korla. The forcing effect of each diagnostic term in the equation on the zonal wind speed was analyzed. The results showed that the advection term was the dominant factor forcing the zonal wind speed. The wave term had a secondary forcing role, although the forcing effect of the wave term on the zonal wind speed was significant in some regions.
基金supported by the Natural Science Foundation for Distinguished Young Scholars of Jiangsu Province under Grant No. BK20160034in part by the National Natural Science Foundation of China under Grant No. 61671473 and No. 61631020in part by the Open Research Foundation of Science and Technology on Communication Networks Laboratory
文摘This paper investigates the channel diversity problem in high frequency(HF) communication systems. Due to the limited HF spectrum resources, a HF communication system with shared channels is considered, where each user equipment(UE) has individual communication demand. In order to maximize the communication probability of the whole system, a matching-potential game framework is designed. In detail, the channel diversity problem is decomposed into two sub-problems. One is channel-transmitter matching problem, which can be formulated as a many-to-one matching game. The other is the transmitter allocation problem which decides the transmission object that each transmitter communicates with under channel-transmitter matching result, and this sub-problem can be modeled as a potential game. A multiple round stable matching algorithm(MRSMA) is proposed, which obtains a stable matching result for the first sub-problem, and a distributed BR-based transmitter allocation algorithm(DBRTAA) is designed to reach Nash Equilibrium(NE) of the second sub-problem. Simulation results verify the effectiveness and superiority of the proposed method.
基金support from the World Meteorological Organization–Global Atmosphere Watch Program/WOUDC (https://www.woudc.org/home.php) with respect to the ozonesonde dataset
文摘Boreal summer intraseasonal oscillation(BSISO) of lower tropospheric ozone is observed in the Indian summer monsoon(ISM) region on the basis of ERA-Interim reanalysis data and ozonesonde data from the World Ozone and Ultraviolet Radiation Data Centre. The 30–60-day intraseasonal variation of lower-tropospheric ozone shows a northwest–southeast pattern with northeastward propagation in the ISM region. The most significant ozone variations are observed in the Maritime Continent and western North Pacific. In the tropics, ozone anomalies extend from the surface to 300 hPa; however, in extratropical areas, it is mainly observed under 500 hPa. Precipitation caused by BSISO plays a dominant role in modulating the BSISO of lower-tropospheric ozone in the tropics, causing negative/positive ozone anomalies in phases 1–3/5–6. As the BSISO propagates northeastward to the western North Pacific, horizontal transport becomes relatively more important, increasing/reducing tropospheric ozone via anticyclonic/cyclonic anomalies over the western North Pacific in phases 3–4/7–8.As two extreme conditions of the ISM, most of its active/break events occur in BSISO phases 4–7/1–8 when suppressed/enhanced convection appears over the equatorial eastern Indian Ocean and enhanced/suppressed convection appears over India, the Bay of Bengal, and the South China Sea. As a result, the BSISO of tropospheric ozone shows significant positive/negative anomalies over the Maritime Continent, as well as negative/positive anomalies over India, the Bay of Bengal,and the South China Sea in active/break spells of the ISM. This BSISO of tropospheric ozone is more remarkable in break spells than in active spells of the ISM, due to the stronger amplitude of BSISO in the former.
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDA17010102)。
文摘We present characterizations of the dynamic turbulence in the lower stratosphere measured by a new balloon-based system designed for detecting finer scale dynamic turbulence. The balloon-based system included a constant temperature anemometer(CTA) operating at a sampling rate of 2 k Hz at an ascent speed of 5 m s^(-1)(corresponding to a vertical resolution of 2.5 mm), an industrial personal computer, batteries, sensors for ambient temperature and humidity, an A/D converter, and others. The system was successfully launched to 24 km altitude over Bayannur City, Inner Mongolia Province. Results show the spatial intermittence of the turbulence layers, with clear boundaries between turbulent and nonturbulent regions. This is the first time that the dynamic turbulence spectrum down to the viscous sub-range has been obtained throughout the lower stratosphere over China. With that, the energy dissipation rates of dynamic turbulence could be calculated with high precision. The profile of the dissipation rates varied from 7.37 × 10^(-7) to 4.23 W kg^(-1) and increased with altitude in the stratosphere.
文摘As the strongest subseasonal atmospheric variability during boreal winter, three remarkable sudden stratospheric major warming(SSW) events in the 2000 s are investigated in terms of the Brewer–Dobson circulation(BDC) response. Our study shows that the changes of cross-isentropic velocity during the SSWs are not only confined to the polar region, but also extend to the whole Northern Hemisphere: enhanced descent in the polar region, as well as enhanced ascent in the tropics. When the acceleration of the deep branch of the BDC descends to the middle stratosphere, its strength rapidly decreases over a period of one to two weeks. The acceleration of the deep branch of the BDC is driven by the enhanced planetary wave activity in the mid-to-high-latitude stratosphere. Different from the rapid response of the deep branch of the BDC, tropical upwelling in the lower stratosphere accelerates up to 20%–40% compared with the climatology, 20–30 days after the onset of the SSWs,and the acceleration lasts for one to three months. The enhancement of tropical upwelling is associated with the large-scale wave-breaking in the subtropics interacting with the midlatitude and tropical Quasi-Biennial Oscillation–related mean flow.
基金supported by grants from the Strategic Priority Research Program of the Chinese Academy of Sciences(CAS)(Grant No.XDA17010100)the National Natural Science Foundation of China(Grant No.41875043)+1 种基金the Youth Innovation Promotion Association,CAS,theKey Research Program of CAS(Grant No.ZDRW-ZS-2019-1)the External Cooperation Program of CAS(Grant No.GJHZ 1802)。
文摘The balloon-borne Aircore campaign was conducted in Inner Mongolia,China,on June 13 and 142018,which detected carbon dioxide(CO2)and carbon monoxide(CO)profiles from surface to 24 km,showing strong positive and negative correlations between 8 km and 10 km on 13 and 14 June,respectively.Backward trajectories,meteorological analyses,and CO2 horizontal distributions were combined to interpret this phenomenon.The results indicated that the source region experienced a stratospheric intrusion and exhibited a large horizontal CO2 gradient;namely,lower CO concentrations corresponded to higher CO2 concentrations and vice versa.The laminar structure with multiple origins resulted in the highly negative correlation between CO2 and CO in the upper troposphere on 14 June.The contribution of stratospheric air mass to the upper troposphere and that of tropospheric air mass to the lower stratosphere were 26.7%and24.3%,respectively,based on a mass balance approach.Another interesting phenomenon is that CO2 and CO concentrations increased substantially at approximately 8 km on 13 June.An analysis based on the backward trajectory implied that the air mass possibly came from anthropogenic sources.The slope of CO2/CO representing the anthropogenic sources was 87.3 ppm ppm-1.In addition,the CO2 profile showed that there was a large CO2 gradient of 4 ppm km-1 within the boundary layer on 13 June,and this gradient disappeared on 14 June.
基金This work was supported by the National Natural Science Foundation of China(31801126)the Chongqing Talents:Exceptional Young Talents Project(cstc2022ycjhbgzxm0019)the Doctoral Start-up Foundation of Southwest University(SWU120010).
文摘The safety of transgenic technology is a major obstacle in the popularization and use of transgenic silkworms and their products.In sericulture,only the first filial generation(F1)hybrid eggs produced by cross-breeding Japanese and Chinese original strains are usually used for the large-scale breeding of silkworms,but this may result in uncontrolled transgene dispersal during the popularization and application of the F1 hybrid transgenic eggs.To address this issue,we developed a safe and efficient strategy using the GAL4/Upstream activating sequence(UAS)system,the FLP/flippase recognition target(FRT)system,and the gonad-specific expression gene promoters(RSHP1p and Nanosp)for the germ cell-specific automatic excision of foreign DNA in the F1 hybrid transgenic silkworms.We established 2 types of activator strains,R1p::GAL4-Gr and Nsp::GAL4-Gr,containing the testis-specific GAL4 gene expression cassettes driven by RSHP1p or Nanosp,respectively,and 1 type of effector strain,UAS::FLP-Rg,containing the UAS-linked FLP gene expression cassette.The FLP recombinase-mediated sperm-specific complete excision of FRT-flanked target DNA in the F1 double-transgenic silkworms resulting from the hybridization of R1p::GAL4-Gr and UAS::FLP-Rg was 100%,whereas the complete excision efficiency resulting from the hybridization of Nsp::GAL4-Gr and UAS::FLP-Rg ranged from 13.73%to 80.3%.Additionally,we identified a gene,sw11114,that is expressed in both testis and ovary of Bombyx mori,and can be used to establish novel gonad-specific expression systems in transgenic silkworms.This strategy has the potential to fundamentally solve the safety issue in the production of F1 transgenic silkworm eggs and provides an important reference for the safety of transgenic technology in other insect species.
基金supported by the National Natural Science Foundation of China under Grant numbers 72271029,71871023,72061127001,and 72201121National Science and Technology Innovation 2030 Major program under Grant 2022ZD0115403.
文摘With e-commerce concentrating retailers and customers onto one platform,logistics companies(e.g.,JD Logistics)have launched integrated supply chain solutions for corporate customers(e.g.,online retailers)with warehousing,transportation,last-mile delivery,and other value-added services.The platform’s concentration of business flows leads to the consolidation of logistics resources,which allows us to coordinate supply chain operations across different corporate customers.This paper studies the stochastic joint replenishment problem of coordinating multiple suppliers and multiple products to gain the economies of scale of the replenishment setup cost and the warehouse inbound operational cost.To this end,we develop stochastic joint replenishment models based on the general-integer policy(SJRM-GIP)for the multi-supplier and multi-product problems and further reformulate the resulted nonlinear optimization models into equivalent mixed integer second-order conic programs(MISOCPs)when the inbound operational cost takes the square-root form.Then,we propose generalized Benders decomposition(GBD)algorithms to solve the MISOCPs by exploiting the Lagrangian duality,convexity,and submodularity of the sub-problems.To reduce the computational burden of the SJRM-GIP,we further propose an SJRM based on the power-of-two policy and extend the proposed GBD algorithms.Extensive numerical experiments based on practical datasets show that the stochastic joint replenishment across multiple suppliers and multiple products would deliver 13∼20%cost savings compared to the independent replenishment benchmark,and on average the proposed GBD algorithm based on the enhanced gradient cut can achieve more than 90%computational time reduction for large-size problem instances compared to the Gurobi solver.The power-of-two policy is capable of providing high-quality solutions with high computational efficiency.
基金supported by the National Natural Science Foundation of China(Grant Nos.72271029,72061127001,and 72201121)the National Key Research and Development Program of China(Grant No.2018AAA0101602)DongguanI nInovative ResearchTeam Program(Grant No.2018607202007).
文摘Logistics networks (LNs) are essential for the transportation and distribution of goods or services from suppliers to consumers. However, LNs with complex structures are more vulnerable to disruptions due to natural disasters and accidents. To address the LN post-disruption response strategy optimization problem, this study proposes a novel two-stage stochastic programming model with robust delivery time constraints. The proposed model jointly optimizes the new-line-opening and rerouting decisions in the face of uncertain transport demands and transportation times. To enhance the robustness of the response strategy obtained, the conditional value at risk (CVaR) criterion is utilized to reduce the operational risk, and robust constraints based on the scenario-based uncertainty sets are proposed to guarantee the delivery time requirement. An equivalent tractable mixed-integer linear programming reformulation is further derived by linearizing the CVaR objective function and dualizing the infinite number of robust constraints into finite ones. A case study based on the practical operations of the JD LN is conducted to validate the practical significance of the proposed model. A comparison with the rerouting strategy and two benchmark models demonstrates the superiority of the proposed model in terms of operational cost, delivery time, and loading rate.
基金Supported by the Strategic Priority Research Program of Chinese Academy of Sciences(XDA17010105)Key Laboratory of Middle Atmosphere and Global Environment Observation(LAGEO-2019-01).
文摘Using NCEP/NCAR reanalysis data, we investigate the statistical characteristics and the long-term variations of major sudden stratospheric warming(SSW) events in the Northern Hemisphere. We find that the strength and duration of major SSW events have increased from 1958 to 2019 because of the strengthening of winter planetary wave activity. The frequency of the SSW events related to displacement or split of the polar vortex differs between early,middle, and late winter. Early(middle) winter is dominated by displacement(split) SSW events, while late winter sees almost equal frequency of these two types of events. This is due to the differences in the relative strength of wavenumber-1 and wavenumber-2 planetary wave activity among the three winter periods. As a result of the increase in upward planetary wave activity and the decrease in westerly winds around the polar vortex in middle winter, more SSW events tend to occur in middle winter. In addition, we reveal the influence of the downward propagation of different types of SSW events on the surface temperature anomaly. Compared with early displacement SSW events, middle split SSW events are followed by more surface cold centers in Russia, northern China, and North America.