The dynamic physical characteristics of a DC arc on an arcing horn for a high voltage direct current(HVDC)grounding electrode line are significantly different from those of the switching device arc,secondary arc,AC fa...The dynamic physical characteristics of a DC arc on an arcing horn for a high voltage direct current(HVDC)grounding electrode line are significantly different from those of the switching device arc,secondary arc,AC fault arc and pantograph-catenary arc.In this work,an experimental platform for the DC arc on the arcing horn was built,and mechanisms of the arc column short circuit and arc root movement were studied.This work further analyzes the characteristics and mechanisms of the arc motion when wind speed and direction,magnetic field and the expansion angle of the electrode are varied.Arc root movement is more likely to occur at the upper electrode.There is a competitive relationship between arc expansion and the transferring effect.The effect of wind on the arc column is greater than the effect on the arc root.The magnetic field has a significant driving effect on both the arc column and the arc root.The research results provide a comprehensive experimental basis for forther probing the method of DC arc suppression,and the improvement of the arcing horn.展开更多
In the distribution network system with its neutral point grounding via arc suppression coil, when single-phase grounding fault occurred near zero-crossing point of the phase voltage, the inaccuracy of the line select...In the distribution network system with its neutral point grounding via arc suppression coil, when single-phase grounding fault occurred near zero-crossing point of the phase voltage, the inaccuracy of the line selection always existed in existing methods. According to the characteristics that transient current was different between the fault feeder and other faultless feeders, wavelet transformation was performed on data of the transient current within a power frequency cycle after the fault occurred. Based on different fault angles, wavelet energy in corresponding frequency band was chosen to compare. The result was that wavelet energy in fault feeder was the largest of all, and it was larger than sum of those in other faultless feeders, when the bus broke down, the disparity between each wavelet energy was not significant. Fault line could be selected out by the criterion above. The results of MATLAB/simulink simulation experiment indicated that this method had anti-interference capacity and was feasible.展开更多
Delineation of the grounding line(GL) is necessary for calculating the mass balance of Antarctica, but GL measurements for most of the continent remain at a relatively coarse level. We used Sentinel-1 constellation da...Delineation of the grounding line(GL) is necessary for calculating the mass balance of Antarctica, but GL measurements for most of the continent remain at a relatively coarse level. We used Sentinel-1 constellation data to map the GL of the Amery Ice Shelf(AIS) using double-differential synthetic aperture radar interferometry. The ice thickness anomaly deduced from hydrostatic equilibrium and existing Antarctic GL products is compared with our result. With this new and very accurate GL, we detected new ice rises in the north of the AIS. Our new measurement shows no major change of the AIS GL, particularly in the southernmost part.展开更多
The Pacific oyster,Crassostrea gigas,naturally distributing along the coast of northwest Pacific,is one of the most important bivalve species due to its high economic value and fecundity.In China,we have initiated a s...The Pacific oyster,Crassostrea gigas,naturally distributing along the coast of northwest Pacific,is one of the most important bivalve species due to its high economic value and fecundity.In China,we have initiated a selective breeding program on both shell color and growth rate of C.gigas since 2010.A black shell line was obtained through four-generation family selection.In this study,mass selection for growth improvement was conducted in the sixth generation and seventh generation of black shell lines.To assess the progress of potential genetic improvement,the progeny of two generations of black shell lines were selected to evaluate their shell heights via a 450-day farming experiment.As the results,after growing for 450 days,the sixth generation and seventh generation of selected lines were 9.03% and 11.42% larger than the control lines,respectively.During the grow-out stage,the genetic gain of two generations was 8.82%±0.18% and 11.54%±0.43%,respectively;and the corresponding realized heritability was 0.45±0.04 and 0.41±0.04,respectively.These results indicated that the mass selection for shell height achieved steady progress in the two generations of C.gigas.展开更多
Pruning is time-consuming and laborious in watermelon cultivation,which can not meet the needs for simplified cultivation in the future.The development of branchless lines will provide important germplasms for breedin...Pruning is time-consuming and laborious in watermelon cultivation,which can not meet the needs for simplified cultivation in the future.The development of branchless lines will provide important germplasms for breeding watermelon varieties and is an important method for genetic improvement.In this study,the watermelon accession,Wu Cha Zao(WCZ)is a branchless inbred line that carries the branchless gene Clbl,which was used as the donor parent to develop branchless near isogenic lines(NILs).To construct the NILs of Clbl,WCZ crossed with the normal branching watermelon inbred line WT20 which was used as the recurrent parent.The co-segregating markers dCAPS10 and Indel1 with Clbl were used for foreground selection,and a total of 108 SSR markers was selected with good polymorphism between two parental lines for background selection which had relatively uniform distribution across 11 chromosomes.Using these markers to select individuals from the BC_(1)F_(1),BC_(2)F_(1),and BC_(2)F_(2) generations,three NILs with a proportion of recurrent parent genome(PRPG)>99%were finally obtained.The lateral branch and plant height phenotypes did not significantly differ between the NILs and WCZ,indicating that the NILs of Clbl under the genetic background of WT20 has been successfully developed.These results provide ideal materials for further in-depth analysis of the genetic mechanisms of lateral branch development and ideal plant architecture breeding in watermelon.展开更多
Four successive mass selection lines of the Pacific oyster, Crassostrea gigas, selected for faster growth in breeding programs in China were examined at ten polymorphic microsatellite loci to assess the level of allel...Four successive mass selection lines of the Pacific oyster, Crassostrea gigas, selected for faster growth in breeding programs in China were examined at ten polymorphic microsatellite loci to assess the level of allelic diversity and estimate the effective population size. These data were compared with those of their base population. The results showed that the genetic variation of the four generations were maintained at high levels with an average allelic richness of 18.8–20.6, and a mean expected heterozygosity of 0.902–0.921. They were not reduced compared with those of their base population. Estimated effective population sizes based on temporal variances in microsatellite frequencies were smaller to that of sex ratio-corrected broodstock count estimates. Using a relatively large number of broodstock and keeping an equal sex ratio in the broodstock each generation may have contributed to retaining the original genetic diversity and maintaining relatively large effective population size. The results obtained in this study showed that the genetic variation was not affected greatly by mass selection progress and high genetic variation still existed in the mass selection lines, suggesting that there is still potential for increasing the gains in future generations of C. gigas. The present study provided important information for future genetic improvement by selective breeding, and for the design of suitable management guidelines for genetic breeding of C. gigas.展开更多
[Objective]This experiment aimed to establish fast and slow feathering lines from purified and rejuvenated core breeding flock. [Method] Individual and family selection were used for continuous selection from zero to ...[Objective]This experiment aimed to establish fast and slow feathering lines from purified and rejuvenated core breeding flock. [Method] Individual and family selection were used for continuous selection from zero to the second generation. [Result]The results showed that in the fast feathering line,the average weight gain was improved by 108. 34 g per generation in roosters at the age of 20 weeks while a 54. 5 g increase was got per generation in hens. Hen housed egg production was increased from 150 to 170 at the age of 66 weeks,and the healthy rate of chicken flock was raised by 0. 7 percent. In the slow feathering line,the average weight gain was increased by 156. 6g per generation in roosters while a 38. 9 g increase was got per generation in hens,and the hen housed egg production was increased from 158 to 179 at the age of 66 weeks. [Conclusion] This research had a great significance in increasing native chicken's production performance and developing its market competitiveness.展开更多
Guangxi common wild rice variety brown planthopper highly resistant introgression line HS204 was taken as antigen donor material,hybridization,backcrossing,and molecular marker-assisted selection methods were adopted,...Guangxi common wild rice variety brown planthopper highly resistant introgression line HS204 was taken as antigen donor material,hybridization,backcrossing,and molecular marker-assisted selection methods were adopted,to select maintainer line and sterile line materials,so as to provide excellent material foundation for resistance breeding of hybrid rice. Through the marker-assisted selection,it obtained 4 pieces of homozygous resistance gene maintainer line intermediate materials( 100B,101B,102B and 103B),and 2 pieces of resistant sterile line materials( 100A and 103A). All 10 combinations that have testcross with highly resistant sterile 100A showed higher level of brown planthopper resistance: 100A/R2586,100A/KR838,and 100A/KR527 had high resistance level,the others had low to intermediate resistance;100A/KR527,100A/R2586,100A/Minghui 63,100A/Fuhui 838 and 100A/Gui 99 combinations had yield per plant significantly higher than the control group( Teyou 7118),increasing by 14. 45%-49. 26%. The obtained resistant lines are expected to provide a better gene source for the breeding of resistant sterile lines of hybrid rice and the obtained resistant sterile lines can be directly used in the selection of three-line hybrid rice.展开更多
The arc-suppression coil(ASC)in parallel low resistance(LR)multi-mode grounding is adopted in the mountain wind farm to cope with the phenomenon that is misoperation or refusal of zero-sequence protection in LR ground...The arc-suppression coil(ASC)in parallel low resistance(LR)multi-mode grounding is adopted in the mountain wind farm to cope with the phenomenon that is misoperation or refusal of zero-sequence protection in LR grounding wind farm.If the fault disappears before LR is put into the system,it is judged as an instantaneous fault;while the fault does not disappear after LR is put into the system,it is judged as a permanent fault;the single-phase grounding fault(SLG)protection criterion based on zerosequence power variation is proposed to identify the instantaneous-permanent fault.Firstly,the distribution characteristic of zero-sequence voltage(ZSV)and zero-sequence current(ZSC)are analyzed after SLGfault occurs in multi-mode grounding.Then,according to the characteristics that zero-sequence power variation of non-fault collector line is small,while the zero-sequence power variation of fault collector line can reflect the active power component of fault resistance,the protection criterion based on zero-sequence power variation is constructed.The theoretical analysis and simulation results show that the protection criterion can distinguish the property of fault only by using the single terminal information,which has high reliability.展开更多
On the basis of ascertaining the dominant and recessive relationship and separation ratio of quality traits such as leaf type and peel stripes,the separation of dominant and recessive traits was studied to infer wheth...On the basis of ascertaining the dominant and recessive relationship and separation ratio of quality traits such as leaf type and peel stripes,the separation of dominant and recessive traits was studied to infer whether the genes of the previous generation were homozygous.Individuals with homozygous recessive traits can be confirmed in F2 generation,and homozygous single lines with dominant traits can be confirmed in F3 generation,which speeds up the breeding process of watermelon inbred lines.展开更多
The broad-spectrum blast resistance gene Pi-1, from donor line BL122, was introduced into a thermo-sensitive genic male sterile rice line GD-8S, which possessed good grain quality but high susceptibility to rice blast...The broad-spectrum blast resistance gene Pi-1, from donor line BL122, was introduced into a thermo-sensitive genic male sterile rice line GD-8S, which possessed good grain quality but high susceptibility to rice blast, by using backcross breeding and molecular marker-assisted selection. Five elite improved male sterile lines, RGD8S-1, RGD8S-2, RGD8S-3, RGD8S-4 and RGD8S-5, were selected based on the results of molecular marker analysis, spikelet sterility, recovery rate of genetic background and agronomic traits. Thirty-three representative blast isolates collected from Guangdong Province, China were used to inoculate the improved lines and the original line GD-8S artificially. The resistance frequencies of the improved lines ranged from 76.47% to 100%, much higher than that of the original line GD-8S (9.09%). On the agronomic characters, there were no significant differences between the improved lines and GD-8S except for flag leaf length and panicle number per plant. The improved lines could be used for breeding hybrid rice with high blast resistance.展开更多
Two bacterial blight (BB) resistance genes, Xa21 and Xa4, from IRBB24 were introduced into hybrid rice restorer line Mianhui 725, which is highly susceptible to BB, by using hybridization and molecular marker-assisted...Two bacterial blight (BB) resistance genes, Xa21 and Xa4, from IRBB24 were introduced into hybrid rice restorer line Mianhui 725, which is highly susceptible to BB, by using hybridization and molecular marker-assisted selection technology. Four homologous restorer lines were obtained through testing the R target genes with molecular markers and analyzing parental genetic background. Inoculation of the four lines and their hybrids with the specific strains of Xanthomonas oryzae pv. oryzae, P1, P6 and seven representative strains of Chinese pathotype, CⅠ-CⅦ, showed that all of the four lines and their hybrids were highly resistant and presented broad resistance-spectrum to BB. The hybrids of G46A / R207-2 displayed good agronomic characters and high yield potential, and R207-2 was named Shuhui 207.展开更多
According to the topography of mountains, the discrete data points from map of the whole region are first subdivided into subregions with the points taken from the feature lines of ridge, valley and scarp being insert...According to the topography of mountains, the discrete data points from map of the whole region are first subdivided into subregions with the points taken from the feature lines of ridge, valley and scarp being inserted into the map point set, and using the feature lines as the boundaries of subregions to build constrained Delaunay TIN. Such an approach has the advantages of ensuring high accuracy and fast speed of line layout.展开更多
China has been promoting the renovation of old residential communities vigorously.Due to the financial pressure of the government and the sustainability of the renovation of old residential communities,public-private ...China has been promoting the renovation of old residential communities vigorously.Due to the financial pressure of the government and the sustainability of the renovation of old residential communities,public-private partnerships(PPP)have already gained attention.The selection of social capital is key to improving the efficiency of the PPP model in renovating old residential communities.In order to determine the influencing factors of social capital selection in the renovation of old residential communities,this paper aims to find an effective approach and analyze these factors.In this paper,a fuzzy decision-making and trial evaluation laboratory(fuzzy-DEMATEL)technique is extended and amore suitable systemis developed for the selection of social capital using the existing group decisionmaking theory.In the first stage,grounded theory is used to extract the unabridged key influencing factors for social capital selection in the renovation of old residential communities.Secondly,by considering the impact of expert weights,the key influencing factors are identified.The interactions within these influencing factors are discussed and the credibility of the results is verified by sensitivity analysis.Finally,these key influencing factors are sorted by importance.Based on the results,the government should focus on a technical level,organizationalmanagement abilities,corporate reputation,credit status,etc.This study provides the government with a theoretical basis and a methodology for evaluating social capital selection.展开更多
In solving many-objective optimization problems(MaO Ps),existing nondominated sorting-based multi-objective evolutionary algorithms suffer from the fast loss of selection pressure.Most candidate solutions become nondo...In solving many-objective optimization problems(MaO Ps),existing nondominated sorting-based multi-objective evolutionary algorithms suffer from the fast loss of selection pressure.Most candidate solutions become nondominated during the evolutionary process,thus leading to the failure of producing offspring toward Pareto-optimal front with diversity.Can we find a more effective way to select nondominated solutions and resolve this issue?To answer this critical question,this work proposes to evolve solutions through line complex rather than solution points in Euclidean space.First,Plücker coordinates are used to project solution points to line complex composed of position vectors and momentum ones.Besides position vectors of the solution points,momentum vectors are used to extend the comparability of nondominated solutions and enhance selection pressure.Then,a new distance function designed for high-dimensional space is proposed to replace Euclidean distance as a more effective distancebased estimator.Based on them,a novel many-objective evolutionary algorithm(MaOEA)is proposed by integrating a line complex-based environmental selection strategy into the NSGAⅢframework.The proposed algorithm is compared with the state of the art on widely used benchmark problems with up to 15 objectives.Experimental results demonstrate its superior competitiveness in solving MaOPs.展开更多
Input ground motions have significant impacts on the uncertainty of structural responses in time-history analysis.In this study,records were selected and scaled for the evaluation of mean structural responses accordin...Input ground motions have significant impacts on the uncertainty of structural responses in time-history analysis.In this study,records were selected and scaled for the evaluation of mean structural responses according to the target spectrum.The Newmark-Hall spectrum is closely related to seismic response of short,medium and long-period structures,so it was taken as the target spectrum here.The nonlinear time-history analyses of 9-story and 20-story steel moment-resisting frame structures were carried out as examples.They represent medium and long-period buildings,respectively.Three target spectra with risk of 50%,10%and 2%probabilities for exceedance in 50 years were calculated by the average Newmark-Hall spectrum method for three ground motion sets developed in the SAC Steel Project.The predicted structural mean responses of these Newmark-Hall spectra were compared with those calculated by the average spectral acceleration method for the same record set.It is found that both methods have similar accuracy for estimating the structural mean response.However,the method proposed herein is more effective in reducing the variability of the structural responses.Also,the proposed method is more advantageous for the time-history analysis of long-period structures or structures with more severe nonlinear responses under strong seismic excitations.展开更多
Genetic improvement is one of the most effective strategies to prevent rice from blast and bacterial blight(BB) diseases,the two most prevalent diseases jeopardizing rice production.Rice hybrids with dural resistance ...Genetic improvement is one of the most effective strategies to prevent rice from blast and bacterial blight(BB) diseases,the two most prevalent diseases jeopardizing rice production.Rice hybrids with dural resistance to blast and BB are needed for sustainable production of food.An incomplete diallele design resulted in 25 crosses between five blast and five BB resistant germplasm accessions.Only one pair of parents,DH146 × TM487,showed polymorphism for all the markers to identify one blast resistance gene Pi25 and three BB resistance genes,Xa21,xa13 and xa5,thus it was used in the marker-assisted selection(MAS).F2 individuals of DH146 × TM487 were genotyped using flanking markers of RM3330 and sequence tagged site(STS) marker SA7 for Pi25.The resistant F2 plants with Pi25 were used for pyramiding BB resistance genes Xa21,xa13 and xa5 identified by the markers pTA248,RM264 and RM153,respectively in subsequent generations.Finally,after selection for agronomic traits and restoration ability among 12 pyramided lines,we acquired an elite restorer line,R8012 including all four target genes(Pi25+Xa21+xa13+xa5).Hybrid Zhong 9A/R8012 derived from the selected line showed stronger resistance to blast and BB,and higher grain yield than the commercial checks uniformally in experimental plots,2007 state-wide yield trial and 2008 nation-wide yield trial.This study provides a paradigmatic example to show that MAS is a practically feasible tool in effectively pyramiding multiple resistance genes.The resultant restoring line and its hybrid would play an important role in securing rice production in China.展开更多
基金National Natural Science Foundation of China(No.51907168)funded by Sichuan Science and Technology Program(Outstanding Youth Science and Technology Talents)(No.2020JDJQ0039)。
文摘The dynamic physical characteristics of a DC arc on an arcing horn for a high voltage direct current(HVDC)grounding electrode line are significantly different from those of the switching device arc,secondary arc,AC fault arc and pantograph-catenary arc.In this work,an experimental platform for the DC arc on the arcing horn was built,and mechanisms of the arc column short circuit and arc root movement were studied.This work further analyzes the characteristics and mechanisms of the arc motion when wind speed and direction,magnetic field and the expansion angle of the electrode are varied.Arc root movement is more likely to occur at the upper electrode.There is a competitive relationship between arc expansion and the transferring effect.The effect of wind on the arc column is greater than the effect on the arc root.The magnetic field has a significant driving effect on both the arc column and the arc root.The research results provide a comprehensive experimental basis for forther probing the method of DC arc suppression,and the improvement of the arcing horn.
文摘In the distribution network system with its neutral point grounding via arc suppression coil, when single-phase grounding fault occurred near zero-crossing point of the phase voltage, the inaccuracy of the line selection always existed in existing methods. According to the characteristics that transient current was different between the fault feeder and other faultless feeders, wavelet transformation was performed on data of the transient current within a power frequency cycle after the fault occurred. Based on different fault angles, wavelet energy in corresponding frequency band was chosen to compare. The result was that wavelet energy in fault feeder was the largest of all, and it was larger than sum of those in other faultless feeders, when the bus broke down, the disparity between each wavelet energy was not significant. Fault line could be selected out by the criterion above. The results of MATLAB/simulink simulation experiment indicated that this method had anti-interference capacity and was feasible.
基金supported by National Program on Key Basic Research Project (Program 973, Grant no. 2013CBA01804)National Natural Science Foundation of China (Grant nos. 41531069 and 41376187)Chinese Polar Environment Comprehensive Investigation & Assessment Program (Grant no. CHINARE2016-02-04)
文摘Delineation of the grounding line(GL) is necessary for calculating the mass balance of Antarctica, but GL measurements for most of the continent remain at a relatively coarse level. We used Sentinel-1 constellation data to map the GL of the Amery Ice Shelf(AIS) using double-differential synthetic aperture radar interferometry. The ice thickness anomaly deduced from hydrostatic equilibrium and existing Antarctic GL products is compared with our result. With this new and very accurate GL, we detected new ice rises in the north of the AIS. Our new measurement shows no major change of the AIS GL, particularly in the southernmost part.
基金supported by the grants from the National Natural Science Foundation of China (Nos. 3177 2843, 31741122)the Earmarked Fund for Agriculture Seed Improvement Project of Shandong Province (No. 2017LZGC009)the Fundamental Research Funds for the Central Universities (No. 201762014)
文摘The Pacific oyster,Crassostrea gigas,naturally distributing along the coast of northwest Pacific,is one of the most important bivalve species due to its high economic value and fecundity.In China,we have initiated a selective breeding program on both shell color and growth rate of C.gigas since 2010.A black shell line was obtained through four-generation family selection.In this study,mass selection for growth improvement was conducted in the sixth generation and seventh generation of black shell lines.To assess the progress of potential genetic improvement,the progeny of two generations of black shell lines were selected to evaluate their shell heights via a 450-day farming experiment.As the results,after growing for 450 days,the sixth generation and seventh generation of selected lines were 9.03% and 11.42% larger than the control lines,respectively.During the grow-out stage,the genetic gain of two generations was 8.82%±0.18% and 11.54%±0.43%,respectively;and the corresponding realized heritability was 0.45±0.04 and 0.41±0.04,respectively.These results indicated that the mass selection for shell height achieved steady progress in the two generations of C.gigas.
基金supported by the National Natural Science Foundation of China(Grant Nos.32102389,32172602,32172574)the Funding of Joint Research on Agricultural Varietie Improvement of Henan Province(Grant No.2022010503)+4 种基金the Zhongyuan Youth Talent Support Program(Grant No.ZYQR201912161)the Program for Science&Technology Innovation Talents in Universities of Henan Province(Grant No.21HASTIT038)the Key Scientific and Technological Project of Henan Province(Grant No.202102110045)the Major Science and Technology Project of Henan Province(Grant No.221100110400)the Science and Technology Innovation Fund of Henan Agricultural University(Grant No.KJCX2021A14).
文摘Pruning is time-consuming and laborious in watermelon cultivation,which can not meet the needs for simplified cultivation in the future.The development of branchless lines will provide important germplasms for breeding watermelon varieties and is an important method for genetic improvement.In this study,the watermelon accession,Wu Cha Zao(WCZ)is a branchless inbred line that carries the branchless gene Clbl,which was used as the donor parent to develop branchless near isogenic lines(NILs).To construct the NILs of Clbl,WCZ crossed with the normal branching watermelon inbred line WT20 which was used as the recurrent parent.The co-segregating markers dCAPS10 and Indel1 with Clbl were used for foreground selection,and a total of 108 SSR markers was selected with good polymorphism between two parental lines for background selection which had relatively uniform distribution across 11 chromosomes.Using these markers to select individuals from the BC_(1)F_(1),BC_(2)F_(1),and BC_(2)F_(2) generations,three NILs with a proportion of recurrent parent genome(PRPG)>99%were finally obtained.The lateral branch and plant height phenotypes did not significantly differ between the NILs and WCZ,indicating that the NILs of Clbl under the genetic background of WT20 has been successfully developed.These results provide ideal materials for further in-depth analysis of the genetic mechanisms of lateral branch development and ideal plant architecture breeding in watermelon.
基金supported by grants from the National High Technology Research and Development Program (2012AA10A405-6)National Natural Science Foundation of China (31372524)Special Fund for Independent Innovation of Shandong Province (2013CX80202)
文摘Four successive mass selection lines of the Pacific oyster, Crassostrea gigas, selected for faster growth in breeding programs in China were examined at ten polymorphic microsatellite loci to assess the level of allelic diversity and estimate the effective population size. These data were compared with those of their base population. The results showed that the genetic variation of the four generations were maintained at high levels with an average allelic richness of 18.8–20.6, and a mean expected heterozygosity of 0.902–0.921. They were not reduced compared with those of their base population. Estimated effective population sizes based on temporal variances in microsatellite frequencies were smaller to that of sex ratio-corrected broodstock count estimates. Using a relatively large number of broodstock and keeping an equal sex ratio in the broodstock each generation may have contributed to retaining the original genetic diversity and maintaining relatively large effective population size. The results obtained in this study showed that the genetic variation was not affected greatly by mass selection progress and high genetic variation still existed in the mass selection lines, suggesting that there is still potential for increasing the gains in future generations of C. gigas. The present study provided important information for future genetic improvement by selective breeding, and for the design of suitable management guidelines for genetic breeding of C. gigas.
基金Supported by the Ministry of Science and Technology Development Project(10050306003)
文摘[Objective]This experiment aimed to establish fast and slow feathering lines from purified and rejuvenated core breeding flock. [Method] Individual and family selection were used for continuous selection from zero to the second generation. [Result]The results showed that in the fast feathering line,the average weight gain was improved by 108. 34 g per generation in roosters at the age of 20 weeks while a 54. 5 g increase was got per generation in hens. Hen housed egg production was increased from 150 to 170 at the age of 66 weeks,and the healthy rate of chicken flock was raised by 0. 7 percent. In the slow feathering line,the average weight gain was increased by 156. 6g per generation in roosters while a 38. 9 g increase was got per generation in hens,and the hen housed egg production was increased from 158 to 179 at the age of 66 weeks. [Conclusion] This research had a great significance in increasing native chicken's production performance and developing its market competitiveness.
基金Supported by Project of National Natural Science Foundation(31560385)Natural Science Foundation Project of Guangxi(2014GXNSFBA118066 and2015GXNSFAA139060)+1 种基金Science and Technology Planning Project of Guangxi(Gui Ke AB16380138)Scientific Development Fund Project of Guangxi Academy of Agricultural Sciences(2015JM06,2017JM70)
文摘Guangxi common wild rice variety brown planthopper highly resistant introgression line HS204 was taken as antigen donor material,hybridization,backcrossing,and molecular marker-assisted selection methods were adopted,to select maintainer line and sterile line materials,so as to provide excellent material foundation for resistance breeding of hybrid rice. Through the marker-assisted selection,it obtained 4 pieces of homozygous resistance gene maintainer line intermediate materials( 100B,101B,102B and 103B),and 2 pieces of resistant sterile line materials( 100A and 103A). All 10 combinations that have testcross with highly resistant sterile 100A showed higher level of brown planthopper resistance: 100A/R2586,100A/KR838,and 100A/KR527 had high resistance level,the others had low to intermediate resistance;100A/KR527,100A/R2586,100A/Minghui 63,100A/Fuhui 838 and 100A/Gui 99 combinations had yield per plant significantly higher than the control group( Teyou 7118),increasing by 14. 45%-49. 26%. The obtained resistant lines are expected to provide a better gene source for the breeding of resistant sterile lines of hybrid rice and the obtained resistant sterile lines can be directly used in the selection of three-line hybrid rice.
基金This paper is supported in part by the National Natural Science Foundations of China,and the Major Science and Technology Projects in Yunnan Province under Grant Nos.51667010,51807085,and 202002AF080001.
文摘The arc-suppression coil(ASC)in parallel low resistance(LR)multi-mode grounding is adopted in the mountain wind farm to cope with the phenomenon that is misoperation or refusal of zero-sequence protection in LR grounding wind farm.If the fault disappears before LR is put into the system,it is judged as an instantaneous fault;while the fault does not disappear after LR is put into the system,it is judged as a permanent fault;the single-phase grounding fault(SLG)protection criterion based on zerosequence power variation is proposed to identify the instantaneous-permanent fault.Firstly,the distribution characteristic of zero-sequence voltage(ZSV)and zero-sequence current(ZSC)are analyzed after SLGfault occurs in multi-mode grounding.Then,according to the characteristics that zero-sequence power variation of non-fault collector line is small,while the zero-sequence power variation of fault collector line can reflect the active power component of fault resistance,the protection criterion based on zero-sequence power variation is constructed.The theoretical analysis and simulation results show that the protection criterion can distinguish the property of fault only by using the single terminal information,which has high reliability.
文摘On the basis of ascertaining the dominant and recessive relationship and separation ratio of quality traits such as leaf type and peel stripes,the separation of dominant and recessive traits was studied to infer whether the genes of the previous generation were homozygous.Individuals with homozygous recessive traits can be confirmed in F2 generation,and homozygous single lines with dominant traits can be confirmed in F3 generation,which speeds up the breeding process of watermelon inbred lines.
基金supported by the grants from the High-Tech Research and Development Program of China (Grant No. 2001AA241011 and No. 2003AA212052)the Major Sci-Tech Program of Guangdong Province, China (Grant No. 2003A2010101 and No. 2006A2020201)the Agricultural Scientific Program of Guangdong Province, China (Grant No. 2005B20101006)
文摘The broad-spectrum blast resistance gene Pi-1, from donor line BL122, was introduced into a thermo-sensitive genic male sterile rice line GD-8S, which possessed good grain quality but high susceptibility to rice blast, by using backcross breeding and molecular marker-assisted selection. Five elite improved male sterile lines, RGD8S-1, RGD8S-2, RGD8S-3, RGD8S-4 and RGD8S-5, were selected based on the results of molecular marker analysis, spikelet sterility, recovery rate of genetic background and agronomic traits. Thirty-three representative blast isolates collected from Guangdong Province, China were used to inoculate the improved lines and the original line GD-8S artificially. The resistance frequencies of the improved lines ranged from 76.47% to 100%, much higher than that of the original line GD-8S (9.09%). On the agronomic characters, there were no significant differences between the improved lines and GD-8S except for flag leaf length and panicle number per plant. The improved lines could be used for breeding hybrid rice with high blast resistance.
文摘Two bacterial blight (BB) resistance genes, Xa21 and Xa4, from IRBB24 were introduced into hybrid rice restorer line Mianhui 725, which is highly susceptible to BB, by using hybridization and molecular marker-assisted selection technology. Four homologous restorer lines were obtained through testing the R target genes with molecular markers and analyzing parental genetic background. Inoculation of the four lines and their hybrids with the specific strains of Xanthomonas oryzae pv. oryzae, P1, P6 and seven representative strains of Chinese pathotype, CⅠ-CⅦ, showed that all of the four lines and their hybrids were highly resistant and presented broad resistance-spectrum to BB. The hybrids of G46A / R207-2 displayed good agronomic characters and high yield potential, and R207-2 was named Shuhui 207.
基金Supported by National Natural Science Foundation China (50779005)
文摘According to the topography of mountains, the discrete data points from map of the whole region are first subdivided into subregions with the points taken from the feature lines of ridge, valley and scarp being inserted into the map point set, and using the feature lines as the boundaries of subregions to build constrained Delaunay TIN. Such an approach has the advantages of ensuring high accuracy and fast speed of line layout.
基金supported by the National Natural Science Foundation of China(No.62141302)the Humanities Social Science Programming Project of the Ministry of Educa-tion of China(No.20YJA630059)+2 种基金the Natural Science Foundation of Jiangxi Province of China(No.20212BAB201011)the China Postdoctoral Science Foundation(Grant No.2019M662265)the Research Project of Economic and Social Development in Liaoning Province(Grant No.2022lslybkt-053).
文摘China has been promoting the renovation of old residential communities vigorously.Due to the financial pressure of the government and the sustainability of the renovation of old residential communities,public-private partnerships(PPP)have already gained attention.The selection of social capital is key to improving the efficiency of the PPP model in renovating old residential communities.In order to determine the influencing factors of social capital selection in the renovation of old residential communities,this paper aims to find an effective approach and analyze these factors.In this paper,a fuzzy decision-making and trial evaluation laboratory(fuzzy-DEMATEL)technique is extended and amore suitable systemis developed for the selection of social capital using the existing group decisionmaking theory.In the first stage,grounded theory is used to extract the unabridged key influencing factors for social capital selection in the renovation of old residential communities.Secondly,by considering the impact of expert weights,the key influencing factors are identified.The interactions within these influencing factors are discussed and the credibility of the results is verified by sensitivity analysis.Finally,these key influencing factors are sorted by importance.Based on the results,the government should focus on a technical level,organizationalmanagement abilities,corporate reputation,credit status,etc.This study provides the government with a theoretical basis and a methodology for evaluating social capital selection.
基金supported in part by the National Natural Science Foundation of China(51775385)the Natural Science Foundation of Shanghai(23ZR1466000)+3 种基金the Shanghai Industrial Collaborative Science and Technology Innovation Project(2021-cyxt2-kj10)the Innovation Program of Shanghai Municipal Education Commission(202101070007E00098)the Innovation Project of Engineering Research Center of Integration and Application of Digital Learning Technology of MOE(1221046)the Program to Cultivate Middle-Aged and Young Cadre Teacher of Jiangsu Province。
文摘In solving many-objective optimization problems(MaO Ps),existing nondominated sorting-based multi-objective evolutionary algorithms suffer from the fast loss of selection pressure.Most candidate solutions become nondominated during the evolutionary process,thus leading to the failure of producing offspring toward Pareto-optimal front with diversity.Can we find a more effective way to select nondominated solutions and resolve this issue?To answer this critical question,this work proposes to evolve solutions through line complex rather than solution points in Euclidean space.First,Plücker coordinates are used to project solution points to line complex composed of position vectors and momentum ones.Besides position vectors of the solution points,momentum vectors are used to extend the comparability of nondominated solutions and enhance selection pressure.Then,a new distance function designed for high-dimensional space is proposed to replace Euclidean distance as a more effective distancebased estimator.Based on them,a novel many-objective evolutionary algorithm(MaOEA)is proposed by integrating a line complex-based environmental selection strategy into the NSGAⅢframework.The proposed algorithm is compared with the state of the art on widely used benchmark problems with up to 15 objectives.Experimental results demonstrate its superior competitiveness in solving MaOPs.
基金National Natural Science Foundation of Hebei Province under Grant No.E2020202038the National Natural Science Foundation of China under Grant No.51778206。
文摘Input ground motions have significant impacts on the uncertainty of structural responses in time-history analysis.In this study,records were selected and scaled for the evaluation of mean structural responses according to the target spectrum.The Newmark-Hall spectrum is closely related to seismic response of short,medium and long-period structures,so it was taken as the target spectrum here.The nonlinear time-history analyses of 9-story and 20-story steel moment-resisting frame structures were carried out as examples.They represent medium and long-period buildings,respectively.Three target spectra with risk of 50%,10%and 2%probabilities for exceedance in 50 years were calculated by the average Newmark-Hall spectrum method for three ground motion sets developed in the SAC Steel Project.The predicted structural mean responses of these Newmark-Hall spectra were compared with those calculated by the average spectral acceleration method for the same record set.It is found that both methods have similar accuracy for estimating the structural mean response.However,the method proposed herein is more effective in reducing the variability of the structural responses.Also,the proposed method is more advantageous for the time-history analysis of long-period structures or structures with more severe nonlinear responses under strong seismic excitations.
基金supported in part by the National Natural Science Foundation of China (Grant No. 30623006,No. 31101209)the National High Technology Research and Development Program of China (Grant No.2006AA10Z1E8)the Program of Introducing International Advanced Agricultural Science and Technologies (948 Program) of Ministry of Agricultureof China (Grant No. 2006-G51)
文摘Genetic improvement is one of the most effective strategies to prevent rice from blast and bacterial blight(BB) diseases,the two most prevalent diseases jeopardizing rice production.Rice hybrids with dural resistance to blast and BB are needed for sustainable production of food.An incomplete diallele design resulted in 25 crosses between five blast and five BB resistant germplasm accessions.Only one pair of parents,DH146 × TM487,showed polymorphism for all the markers to identify one blast resistance gene Pi25 and three BB resistance genes,Xa21,xa13 and xa5,thus it was used in the marker-assisted selection(MAS).F2 individuals of DH146 × TM487 were genotyped using flanking markers of RM3330 and sequence tagged site(STS) marker SA7 for Pi25.The resistant F2 plants with Pi25 were used for pyramiding BB resistance genes Xa21,xa13 and xa5 identified by the markers pTA248,RM264 and RM153,respectively in subsequent generations.Finally,after selection for agronomic traits and restoration ability among 12 pyramided lines,we acquired an elite restorer line,R8012 including all four target genes(Pi25+Xa21+xa13+xa5).Hybrid Zhong 9A/R8012 derived from the selected line showed stronger resistance to blast and BB,and higher grain yield than the commercial checks uniformally in experimental plots,2007 state-wide yield trial and 2008 nation-wide yield trial.This study provides a paradigmatic example to show that MAS is a practically feasible tool in effectively pyramiding multiple resistance genes.The resultant restoring line and its hybrid would play an important role in securing rice production in China.
