Today, energy saving is one of the main objectives for engineers. In the case of mobile applications, energy can be saved by two different ways： decreasing the total masse of the system and increasing the efficiency ...Today, energy saving is one of the main objectives for engineers. In the case of mobile applications, energy can be saved by two different ways： decreasing the total masse of the system and increasing the efficiency of the overall system. This paper presents two optimization strategies to design a predefined multichannel structure of a boost converter which is dedicated to a solar airplane and used to interface PV panels and the battery system. The first strategy is a multi-criterion method that is able to trace the dependency between the converter＇s efficiency and its power density through the intermediary of the Pareto front. The second method, a mono-criterion approach, maximizes efficiency while respecting the constraint imposed on power density. The mono-criterion method that is applied to maximizing the European efficiency criterion showed that an increase in the number of channels enhanced the quantity of energy collected over a day by increasing the power density of the converter. At the end of the paper, the optimal design calculated was built to give an example of the result obtained by this design methodology. The results of the efficiency measurements made on a realized prototype are presented in this paper.展开更多
In Non-Orthogonal Multiple Access(NOMA),the best way to fully exploit the benefits of the system is the efficient resource allocation.For the NOMA power domain,the allocation of power and spectrum require solving the ...In Non-Orthogonal Multiple Access(NOMA),the best way to fully exploit the benefits of the system is the efficient resource allocation.For the NOMA power domain,the allocation of power and spectrum require solving the mixed-integer nonlinear programming NP-hard problem.In this paper,we investigate user scheduling and power allocation in Multi-Cell Multi-Carrier NOMA(MCMC-NOMA)networks.To achieve that,we consider Weighted Sum Rate Maximization(WSRM)and Weighted Sum Energy Efficiency Maximization(WSEEM)problems.First,we tackle the problem of user scheduling for fixed power using Fractional Programming(FP),the Lagrange dual method,and the decomposition method.Then,we consider Successive Pseudo-Convex Approximation(SPCA)to deal with the WSRM problem.Finally,for the WSEEM problem,SPCA is utilized to convert the problem into separable scalar problems,which can be parallelly solved.Thus,the Dinkelbach algorithm and constraints relaxation are used to characterize the closed-form solution for power allocation.Extensive simulations have been implemented to show the efficiency of the proposed framework and its superiority over other existing schemes.展开更多
Most of the important agronomic traits in crop plants, such as yield, quality and stress response, are quantitative and jointly controlled by many genomic loci or major genes. Improving these complex traits depends on...Most of the important agronomic traits in crop plants, such as yield, quality and stress response, are quantitative and jointly controlled by many genomic loci or major genes. Improving these complex traits depends on the combination of beneficial alleles at the quantitative trait loci （QTLs）. However, the conventional cross breeding method is extremely time-consuming and laborious for pyramiding multiple QTLs. In certain cases, this approach might be technically difficult because of close linkage between genes separately responsible for desirable and undesirable traits.展开更多
We use the directional slacks-based measure of efficiency and inverse distance weighting method to analyze the spatial pattern evolution of the industrial green total factor productivity of 108 cities in the Yangtze R...We use the directional slacks-based measure of efficiency and inverse distance weighting method to analyze the spatial pattern evolution of the industrial green total factor productivity of 108 cities in the Yangtze River Economic Belt in 2003–2013.Results show that both the subprime mortgage crisis and ‘the new normal' had significant negative effects on productivity growth,leading to the different spatial patterns between 2003–2008 and 2009–2013.Before 2008,green poles had gathered around some capital cities and formed a tripartite pattern,which was a typical core-periphery pattern.Due to a combination of the polarization and the diffusion effects,capital cities became the growth poles and ‘core' regions,while surrounding areas became the ‘periphery'.This was mainly caused by the innate advantage of capital cities and ‘the rise of central China' strategy.After 2008,the tripartite pattern changed to a multi-poles pattern where green poles continuously and densely spread in the midstream and downstream areas.This is due to the regional difference in the leading effect of green poles.The leading effect of green poles in midstream and downstream areas has changed from polarization to diffusion,while the polarization effect still leads in the upstream area.展开更多
Increasing leaf photosynthesis per area（A） is of great importance to achieve yield further improvement. The aim of this study was to exploit varietal difference in A and its correlation with specific leaf weight（SL...Increasing leaf photosynthesis per area（A） is of great importance to achieve yield further improvement. The aim of this study was to exploit varietal difference in A and its correlation with specific leaf weight（SLW）. Twelve rice cultivars, including 6 indica and 6 japonica varieties, were pot-grown under two N treatments, low N（LN） and sufficient N（SN）. Leaf photosynthesis and related parameters were measured at tillering stage. Compared with LN treatment, A, stomatal conductance（g_s）, mesophyll conductance（g_m）, leaf N content（N_（area））, and chlorophyll content were significantly improved under SN treatment, while SLW and photosynthetic N use efficiency（PNUE） were generally decreased. Varietal difference in A was positively related to both g_s and g_m, but not related to N_（area）. This resulted in a low PNUE in high N_（area） leaves. Varietal difference in PNUE was generally negatively related to SLW. Response of PNUE to N supply varied among different rice cultivars, and interestingly, the decrease in PNUE under SN was negatively related to the decrease in SLW. With a higher N_（area）, japonica rice cultivars did not show a higher A than indica rice cultivars because of possession of high-SLW leaves. Therefore, varietal difference in A was not related to N_（area）, and SLW can substantially interfere with the correlation between A and N_（area）. These findings may provide useful information for rice breeders to maximize A and PNUE, rather than over reliance on N_（area） as an indicator of photosynthetic performance.展开更多
In recent years,shale gas production horizontal well types mainly include conventional horizontal well,highly deviated well and scoop-shape horizontal well.For the sake of construction decision making,it is necessary ...In recent years,shale gas production horizontal well types mainly include conventional horizontal well,highly deviated well and scoop-shape horizontal well.For the sake of construction decision making,it is necessary to study these three types of wells from the aspects of drag and torque characteristic,weight on bit transferring efficiency,key hole sections or links and extreme penetration length.In this paper,these three types of horizontal wells were taken as the study objects.Their drag and torque,load transfer and extended reach drilling were explored based on the dynamic model of full hole drilling string and the simulation calculation of dynamic characteristics of full hole drilling string system.And the results were applied and tested on site in three shale gas wells(a conventional horizontal well,a highly deviated well and a scoop-shape horizontal well)in the Changning area,Sichuan Basin.And the following research results were obtained.First,the contact friction strength of the deeper part of the buildup section in the scoop-shape horizontal well is very high,and it is 1.67 times that of the hold section.The total contact force of buildup section in the scoop-shape horizontal well is 1.62 times that in the highly deviated well.Second,the contact friction strength of the hold section in highly deviated well is not only higher than that of its buildup section,but also higher than any characteristic section in the three well types of the same depth.Third,the operating stress of drilling strings during the drilling of three well types is not high,but during the extended reach drilling in the curved section of the scoop-shape horizontal well,it is necessary to focus on the twist off of drilling string in the hold section.Fourth,the weight on bit transferring efficiency of scoop-shape horizontal well is lower than that of conventional horizontal well and highly deviated well.In conclusion,the research results preliminarily reveal the drag and torque characteristics and active load transferring mechanisms of conventional horizontal well,highly deviated well and scoop-shape horizontal well for shale gas production,and present important hole sections for safety assessment.They can be used as references for efficient and safe construction of shale gas horizontal wells.展开更多
PREPARATION of HMW DNA (Megabase-size) is the basis for construction of genomic library with large DNA inserts such as bacterial artificial chromosome (BAC) and yeast artificial chromosome (YAC), and for long-range ph...PREPARATION of HMW DNA (Megabase-size) is the basis for construction of genomic library with large DNA inserts such as bacterial artificial chromosome (BAC) and yeast artificial chromosome (YAC), and for long-range physical mapping. It can also be used for the macro-study of repeat sequences. Since HMW DNA during preparation is inclined to be sheared physically and digested by internal nucleases, it is very difficult to prepare the HMW DNA. Initially, plant HMW DNA was prepared by embedding protoplasts in the low melting-point (LMP) agarose; however, it had several disadvantages: (ⅰ) Culture of protoplasts was time-consuming, costly and tedious. ( ⅱ ) It was only used successfully for limited展开更多
文摘Today, energy saving is one of the main objectives for engineers. In the case of mobile applications, energy can be saved by two different ways： decreasing the total masse of the system and increasing the efficiency of the overall system. This paper presents two optimization strategies to design a predefined multichannel structure of a boost converter which is dedicated to a solar airplane and used to interface PV panels and the battery system. The first strategy is a multi-criterion method that is able to trace the dependency between the converter＇s efficiency and its power density through the intermediary of the Pareto front. The second method, a mono-criterion approach, maximizes efficiency while respecting the constraint imposed on power density. The mono-criterion method that is applied to maximizing the European efficiency criterion showed that an increase in the number of channels enhanced the quantity of energy collected over a day by increasing the power density of the converter. At the end of the paper, the optimal design calculated was built to give an example of the result obtained by this design methodology. The results of the efficiency measurements made on a realized prototype are presented in this paper.
基金supported by the National Science Foundation of P.R.China (No.61701064)the Chongqing Natural Science Foundation (cstc2019jcyj-msxmX0264).
文摘In Non-Orthogonal Multiple Access(NOMA),the best way to fully exploit the benefits of the system is the efficient resource allocation.For the NOMA power domain,the allocation of power and spectrum require solving the mixed-integer nonlinear programming NP-hard problem.In this paper,we investigate user scheduling and power allocation in Multi-Cell Multi-Carrier NOMA(MCMC-NOMA)networks.To achieve that,we consider Weighted Sum Rate Maximization(WSRM)and Weighted Sum Energy Efficiency Maximization(WSEEM)problems.First,we tackle the problem of user scheduling for fixed power using Fractional Programming(FP),the Lagrange dual method,and the decomposition method.Then,we consider Successive Pseudo-Convex Approximation(SPCA)to deal with the WSRM problem.Finally,for the WSEEM problem,SPCA is utilized to convert the problem into separable scalar problems,which can be parallelly solved.Thus,the Dinkelbach algorithm and constraints relaxation are used to characterize the closed-form solution for power allocation.Extensive simulations have been implemented to show the efficiency of the proposed framework and its superiority over other existing schemes.
基金supported by Genetically Modified Breeding Major Projects(No.2016ZX08010-002-008)the National Natural Science Foundation of China(Nos.31501239 and 31401454)
文摘Most of the important agronomic traits in crop plants, such as yield, quality and stress response, are quantitative and jointly controlled by many genomic loci or major genes. Improving these complex traits depends on the combination of beneficial alleles at the quantitative trait loci （QTLs）. However, the conventional cross breeding method is extremely time-consuming and laborious for pyramiding multiple QTLs. In certain cases, this approach might be technically difficult because of close linkage between genes separately responsible for desirable and undesirable traits.
基金Under the auspices of the post-funded project of National Social Science Foundation of China(No.16FJL009)
文摘We use the directional slacks-based measure of efficiency and inverse distance weighting method to analyze the spatial pattern evolution of the industrial green total factor productivity of 108 cities in the Yangtze River Economic Belt in 2003–2013.Results show that both the subprime mortgage crisis and ‘the new normal' had significant negative effects on productivity growth,leading to the different spatial patterns between 2003–2008 and 2009–2013.Before 2008,green poles had gathered around some capital cities and formed a tripartite pattern,which was a typical core-periphery pattern.Due to a combination of the polarization and the diffusion effects,capital cities became the growth poles and ‘core' regions,while surrounding areas became the ‘periphery'.This was mainly caused by the innate advantage of capital cities and ‘the rise of central China' strategy.After 2008,the tripartite pattern changed to a multi-poles pattern where green poles continuously and densely spread in the midstream and downstream areas.This is due to the regional difference in the leading effect of green poles.The leading effect of green poles in midstream and downstream areas has changed from polarization to diffusion,while the polarization effect still leads in the upstream area.
基金supported by the National Natural Science Foundation of China(31301840)the National Excellent Doctoral Dissertation of China(201465)+2 种基金the Program for Changjiang Scholars and Innovative Research Team in University of China(IRT1247)the Natural Science Foundation of Hubei Province,China(2013CFB201)the Fundamental Research Funds for the Central Universities,China(2013PY107)
文摘Increasing leaf photosynthesis per area（A） is of great importance to achieve yield further improvement. The aim of this study was to exploit varietal difference in A and its correlation with specific leaf weight（SLW）. Twelve rice cultivars, including 6 indica and 6 japonica varieties, were pot-grown under two N treatments, low N（LN） and sufficient N（SN）. Leaf photosynthesis and related parameters were measured at tillering stage. Compared with LN treatment, A, stomatal conductance（g_s）, mesophyll conductance（g_m）, leaf N content（N_（area））, and chlorophyll content were significantly improved under SN treatment, while SLW and photosynthetic N use efficiency（PNUE） were generally decreased. Varietal difference in A was positively related to both g_s and g_m, but not related to N_（area）. This resulted in a low PNUE in high N_（area） leaves. Varietal difference in PNUE was generally negatively related to SLW. Response of PNUE to N supply varied among different rice cultivars, and interestingly, the decrease in PNUE under SN was negatively related to the decrease in SLW. With a higher N_（area）, japonica rice cultivars did not show a higher A than indica rice cultivars because of possession of high-SLW leaves. Therefore, varietal difference in A was not related to N_（area）, and SLW can substantially interfere with the correlation between A and N_（area）. These findings may provide useful information for rice breeders to maximize A and PNUE, rather than over reliance on N_（area） as an indicator of photosynthetic performance.
基金supported by Sichuan Youth Science and Technology Innovation Team Project“Drilling Speed Increase”(No.:2017TD0014)Sichuan Science and Technology Plan International Cooperation Program“Non-linear Vibration Characteristics of Reaming while Drilling System and Optimization of Reaming Parameters”(No.:2016HH0008).
文摘In recent years,shale gas production horizontal well types mainly include conventional horizontal well,highly deviated well and scoop-shape horizontal well.For the sake of construction decision making,it is necessary to study these three types of wells from the aspects of drag and torque characteristic,weight on bit transferring efficiency,key hole sections or links and extreme penetration length.In this paper,these three types of horizontal wells were taken as the study objects.Their drag and torque,load transfer and extended reach drilling were explored based on the dynamic model of full hole drilling string and the simulation calculation of dynamic characteristics of full hole drilling string system.And the results were applied and tested on site in three shale gas wells(a conventional horizontal well,a highly deviated well and a scoop-shape horizontal well)in the Changning area,Sichuan Basin.And the following research results were obtained.First,the contact friction strength of the deeper part of the buildup section in the scoop-shape horizontal well is very high,and it is 1.67 times that of the hold section.The total contact force of buildup section in the scoop-shape horizontal well is 1.62 times that in the highly deviated well.Second,the contact friction strength of the hold section in highly deviated well is not only higher than that of its buildup section,but also higher than any characteristic section in the three well types of the same depth.Third,the operating stress of drilling strings during the drilling of three well types is not high,but during the extended reach drilling in the curved section of the scoop-shape horizontal well,it is necessary to focus on the twist off of drilling string in the hold section.Fourth,the weight on bit transferring efficiency of scoop-shape horizontal well is lower than that of conventional horizontal well and highly deviated well.In conclusion,the research results preliminarily reveal the drag and torque characteristics and active load transferring mechanisms of conventional horizontal well,highly deviated well and scoop-shape horizontal well for shale gas production,and present important hole sections for safety assessment.They can be used as references for efficient and safe construction of shale gas horizontal wells.
文摘PREPARATION of HMW DNA (Megabase-size) is the basis for construction of genomic library with large DNA inserts such as bacterial artificial chromosome (BAC) and yeast artificial chromosome (YAC), and for long-range physical mapping. It can also be used for the macro-study of repeat sequences. Since HMW DNA during preparation is inclined to be sheared physically and digested by internal nucleases, it is very difficult to prepare the HMW DNA. Initially, plant HMW DNA was prepared by embedding protoplasts in the low melting-point (LMP) agarose; however, it had several disadvantages: (ⅰ) Culture of protoplasts was time-consuming, costly and tedious. ( ⅱ ) It was only used successfully for limited
