When only a portion of the shield lining structures in a full-line tunnel are overloaded,their bearing and failure characteristics are significantly different from those in the full-line overloaded case.In existing st...When only a portion of the shield lining structures in a full-line tunnel are overloaded,their bearing and failure characteristics are significantly different from those in the full-line overloaded case.In existing studies,one or several segmental lining rings have been studied,with overload applied to selected lining rings to analyze the performance evolution of the lining structures;however,this approach fails to reveal the bearing and failure characteristics of shield lining rings under localized overload.To address this research gap,we employ 3D finite element modeling to investigate the mechanical performance and failure mechanisms of shield segmental linings under localized overload conditions,and compare the results with full-line overload scenarios.Additionally,the impact of reinforcing shield segmental linings with steel rings is studied to address issues arising from localized overloads.The results indicate that localized overloads lead to significant ring joint dislocation and higher stress on longitudinal bolts,potentially causing longitudinal bolt failure.Furthermore,the overall deformation of lining rings,segmental joint opening,and stress in circumferential bolts and steel bars is lower compared to full-line overloads.For the same overload level,the convergence deformation of the lining under full-line overload is 1.5 to 2.0 times higher than that under localized overload.For localized overload situations,a reinforcement scheme with steel rings spanning across two adjacent lining rings is more effective than installing steel rings within individual lining rings.This spanning ring reinforcement strategy not only enhances the structural rigidity of each ring,but also limits joint dislocation and reduces stress on longitudinal bolts,with the reduction in maximum ring joint dislocation ranging from 70%to 82%and the reduction in maximum longitudinal bolt stress ranging from 19%to 57%compared to reinforcement within rings.展开更多
This study aims to assess the comprehensive strengthening effect of a steel-ultra high performance concrete(UHPC)composite strengthening method.The axial force-moment interaction curve(N-M curve)was calculated in a no...This study aims to assess the comprehensive strengthening effect of a steel-ultra high performance concrete(UHPC)composite strengthening method.The axial force-moment interaction curve(N-M curve)was calculated in a novel way,using cross-sectional strains at ultimate states as well as real-time stress measurements for each material.The enclosed area of the N-M curve was defined as a comprehensive performance index for the system.We validate our approach with comparisons to numerical modeling and full-scale four-point bending experiments.Additionally,strengthening effects were compared for different sagging and hogging moments based on material stress responses,and the impact of various strengthening parameters was analyzed.We find that the N-M curve of the strengthened cross-section envelops that of the un-strengthened cross-section.Notably,improvements in flexural capacity are greater under sagging moments during the large eccentric failure stage,and greater under hogging moments during the small eccentric failure stage.This discrepancy is attributed to the strength utilization of strengthening materials.These findings provide a reference for understanding the strengthening effects and parameters of steel-UHPC composite.展开更多
Based on the first unde rwater railway shield tunnel, the Shiziyang shield tunnel of Guangzhou Zhu- jiang River, the prototype test was carried out against its segmental lining structure by using ＂multi-function shie...Based on the first unde rwater railway shield tunnel, the Shiziyang shield tunnel of Guangzhou Zhu- jiang River, the prototype test was carried out against its segmental lining structure by using ＂multi-function shield tunnel structure test system＂. And the mechanical characteristics of segmental lining structure using straight assembling and staggered assembling were studied deeply. The results showed that, the mechanical characteristics of segmental lining structure varied with the water pressures; especially after cracking, the high water pressure played a significant role in slowing down the growing inner force and deformation. It also testi- fied that the failure characteristics varied with straight assembling structure and staggered assembling structure. Shear thilurc often occurred near longitudinal seam when using straight assembling.展开更多
The uniform ring model and the shell-spring model for segmental lining design are reviewed in thisarticle. The former is the most promising means to reflect the real behavior of segmental lining, while thelatter is th...The uniform ring model and the shell-spring model for segmental lining design are reviewed in thisarticle. The former is the most promising means to reflect the real behavior of segmental lining, while thelatter is the most popular means in practice due to its simplicity. To understand the relationship and thedifference between these two models, both of them are applied to the engineering practice of FuzhouMetro Line I, where the key parameters used in both models are described and compared. The effectiveratio of bending rigidity h reflecting the relative stiffness between segmental lining and surroundingground and the transfer ratio of bending moment x reflecting the relative stiffness between segment andjoint, which are two key parameters used in the uniform ring model, are especially emphasized. Thereasonable values for these two key parameters are calibrated by comparing the bending momentscalculated from both two models. Through case studies, it is concluded that the effective ratio of bendingrigidity h increases significantly with good soil properties, increases slightly with increasing overburden,and decreases slightly with increasing water head. Meanwhile, the transfer ratio of bending moment xseems to only relate to the properties of segmental lining itself and has a minor relation with the groundconditions. These results could facilitate the design practice for Fuzhou Metro Line I, and could alsoprovide some references to other projects with respect to similar scenarios.展开更多
A series of full-scale loading tests are performed for a prospective subway tunnel with a rectangular shape including two reliability tests: one stagger-jointed three-ring reliability test, and one ultimate failure te...A series of full-scale loading tests are performed for a prospective subway tunnel with a rectangular shape including two reliability tests: one stagger-jointed three-ring reliability test, and one ultimate failure test on a single ring. Comprehensive measuring programs are designed to record the deformation of both lining structure and joints and the stresses of concrete, bolts and reinforcements. Experimental results show that in both the single-ring and three-ring loading cases, the long sides of tunnel cross section bend inwards while the short sides of tunnel cross section bend outwards. The inner part of joints opens while the outer part of joints closes at places experiencing positive moment and vice versa. Joint's rotational stiffness varies at different locations. Concrete cracking and crushing are the chief damage modes, and they are closely related to the distribution of bending moment. Stagger-jointed fabrication significantly increases the overall rigidity of lining system, which thereby greatly reduces the deformation of both concrete lining and joints in comparison with the single-ring case. It is shown that the routinely-used uniform rigidity model is conservative and the preliminary design can be optimized by applying an effective rigidity ratio(ERR) of 0.5.展开更多
Introducing the inherent genetic diversity of wild species into cultivars has become one of the hot topics in crop genetic breeding and genetic resource research.Fiber-and seed-related traits,which are critical to the...Introducing the inherent genetic diversity of wild species into cultivars has become one of the hot topics in crop genetic breeding and genetic resource research.Fiber-and seed-related traits,which are critical to the global economy and people's livelihoods,are the principal focus of cotton breeding.Here,the wild cotton species Gossypium tomentosum was used to broaden the genetic basis of G.hirsutum and identify QTLs for fiber-and seed-related traits.A population of 559 chromosome segment substitution lines(CSSLs)was established with various chromosome segments from G.tomentosum in a G.hirsutum cultivar background.Totals of 72,89,and 76 QTLs were identified for three yield traits,five fiber quality traits,and six cottonseed nutrient quality traits,respectively.Favorable alleles of 104 QTLs were contributed by G.tomentosum.Sixty-four QTLs were identified in two or more environments,and candidate genes for three of them were further identified.The results of this study contribute to further studies on the genetic basis of the morphogenesis of these economic traits,and indicate the great breeding potential of G.tomentosum for improving the fiber-and seed-related traits in G.hirsutum.展开更多
Heading date is one of the most important agronomic traits that directly affect rice yield and determines the regional adaptability in specific growing environments.As a short-day plant,rice can grow under long-day(LD...Heading date is one of the most important agronomic traits that directly affect rice yield and determines the regional adaptability in specific growing environments.As a short-day plant,rice can grow under long-day(LD)conditions due to the synergistic regulation of many photosensitive genes.Using a set of chromosome segment substitution lines(CSSLs)with the indica cultivar Huanghuazhan(HHZ)as the recipient parent and Basmati Surkh 89-15(BAS)as the donor parent,we identified a QTL locus.展开更多
With the continuous growth of signal frequency and package density, discontinuity of the high-frequency interconnection in 3 D micro/nano integration becomes unavoidable, which results in serious signal integrity prob...With the continuous growth of signal frequency and package density, discontinuity of the high-frequency interconnection in 3 D micro/nano integration becomes unavoidable, which results in serious signal integrity problems. Traditional interconnection design schemes, such as termination and shielding/isolation, cannot meet the requirements under the unified constraints of specific cost, space occupancy, and performance. In this study, a transmission line design optimization scheme based on the segmental transmission line(STL) methodology is proposed. The genetic algorithm is used to select the optimal segment structure parameters of the transmission line to construct an STL with satisfying transmission performance or meet the specific signal amplitude adjustment requirements. This scheme can be adapted to various signal transmission scenarios to significantly improve the signal loss caused by reflection or other negative electromagnetic factors and meet the requirements for the modeling of discontinuous transmission lines. The simulation results show that this scheme is effective in the design scenario of performance improvement or equivalent modeling of discontinuous transmission lines and has significant advantages in circuit area reduction.展开更多
Over the last decades,an expansion of the underground network has been taking place to cope with the increasing amount of moving people and freight.As a consequence,it is of vital importance to guarantee the full func...Over the last decades,an expansion of the underground network has been taking place to cope with the increasing amount of moving people and freight.As a consequence,it is of vital importance to guarantee the full functionality of the tunnel network by means of preventive maintenance and the monitoring of the tunnel lining state over time.A new method has been developed for the real-time prediction of the utilization level in tunnel segmental linings based on input monitoring data.The new concept is founded on a framework,which encompasses an offline and an online stage.In the former,the generation of feedforward neural networks is accomplished by employing synthetically produced data.Finite element simulations of the lining structure are conducted to analyze the structural response under multiple loading conditions.The scenarios are generated by assuming ranges of variation of the model input parameters to account for the uncertainty due to the not fully determined in situ conditions.Input and target quantities are identified to better assess the structural utilization of the lining.The latter phase consists in the application of the methodological framework on input monitored data,which allows for a real-time prediction of the physical quantities deployed for the estimation of the lining utilization.The approach is validated on a full-scale test of segmental lining,where the predicted quantities are compared with the actual measurements.Finally,it is investigated the influence of artificial noise added to the training data on the overall prediction performances and the benefits along with the limits of the concept are set out.展开更多
Segmental tunnel lining strengthened with steel plates is widely used worldwide to provide a permanent strengthening method.Most existing studies assume an ideal steel-concrete interface,ignoring discontinuous deforma...Segmental tunnel lining strengthened with steel plates is widely used worldwide to provide a permanent strengthening method.Most existing studies assume an ideal steel-concrete interface,ignoring discontinuous deformation characteristics,making it difficult to accurately analyze the strengthened structure’s failure mechanism.In this study,interfacial fracture mechanics of composite material was applied to the segmental tunnel lining strengthened with steel plates,and a numerical three-dimensional solid nonlinear model of the lining structure was established,combining the extended finite element method with a cohesive-zone model to account for the discontinuous deformation characteristics of the interface.The results accurately describe the crack propagation process,and are verified by full-scale testing.Next,dynamic simulations based on the calibrated model were conducted to analyze the sliding failure and cracking of the steel-concrete interface.Lastly,detailed location of the interface bonding failure are further verified by model test.The results show that,the cracking failure and bond failure of the interface are the decisive factors determining the instability and failure of the strengthened structure.The proposed numerical analysis is a major step forward in revealing the interface failure mechanism of strengthened composite material structures.展开更多
Grain weight, one of the major factors determining rice yield, is a typical quantitative trait control ed by multiple genes. With Guangluai 4 as recipient and Nipponbare as donor, a population of 119 chromosome single...Grain weight, one of the major factors determining rice yield, is a typical quantitative trait control ed by multiple genes. With Guangluai 4 as recipient and Nipponbare as donor, a population of 119 chromosome single segment substitution lines had been developed. Correlation analysis between grain weight and grain shape by SPSS revealed that 1 000-grain weight shared extremely significant posi-tive correlation with grain length and length-width ratio, but no significant correlation with grain width and thickness. The QTL analysis of grain weight was carried out using one-way analysis of variance and Dunnett＇s test. Nineteen stable QTLs re-sponsible for grain weight were identified over two years. Al 19 QTLs were identi-fied on al chromosomes except for chromosome 10 and 12 at a significance level of P≤0.001. Among them, 10 QTLs had a positive effect and were derived from the Nipponbare al ele, the additive effect of these QTLs ranged from 0.49 to 2.74 g, and the contributions of the additive effects ranged from 2.00% to 11.05%. Another 9 QTLs had a negative effect and were al derived from Guangluai 4 al ele, the ad-ditive effect of these QTLs ranged from 0.60 to 2.35 g, and the contributions of the additive effects ranged from 2.40% to 9.84%. The results provide a basis for the fine mapping and gene cloning of novel locus associated with rice grain weight.展开更多
To investigate the mechanical behavior of segmental lining, a three-dimensional numerical analysis and test using three actual segments were used to analyze the effects of axial force and reinforcement ratio on the fa...To investigate the mechanical behavior of segmental lining, a three-dimensional numerical analysis and test using three actual segments were used to analyze the effects of axial force and reinforcement ratio on the failure mechanism and ultimate bearing capacity of segmental lining. Both numerical and test results confirmed that the cracking load, yield and ultimate load were strongly influenced by axial force, and it was also proved that the yield and ultimate load would increase with the increase of reinforcement ratio, but the cracking load was almost not affected. The cracking load, yield and ultimate load are about 28.7%, 500% and 460% larger due to the effect of axial force respectively. The comparison between numerical calculation and test results showed that the finite element analysis resuits were in good agreement with the test results.展开更多
In this study, a population of chromosome segment substitution lines （CSSLs） derived from the cross between 9311 （indica） and Nipponbare （japonica） was employed to map the quantitative trait loci （QTLs） for sa...In this study, a population of chromosome segment substitution lines （CSSLs） derived from the cross between 9311 （indica） and Nipponbare （japonica） was employed to map the quantitative trait loci （QTLs） for salt tolerance under the salt stress simulated with 0.5% NaCI, using survival rate as the index. The data were analyzed by QTL IciMapping v3.1, and the results showed that one QTL （QSsr3） related to salt tolerance was located in the vicinity of the marker RM1350 on chromosome 3, into a genetic interval of 113.2-132.8 cM, with a contribution rate of 17.75%. The additive effect was 10.9, indicating that the QTL derived from the parent Nipponbare improved the salt tolerance of rice at seedling stage. This study will provide a theoretical basis for the selection of salt tolerant rice germplasm.展开更多
In this study, a population of 119 chromosome segment substitution lines （CSSLs） derived from backcross between indica 9311 and japonica Nipponbare was employed to map quantitative trait loci （QTL） associated with...In this study, a population of 119 chromosome segment substitution lines （CSSLs） derived from backcross between indica 9311 and japonica Nipponbare was employed to map quantitative trait loci （QTL） associated with sheath blight resis-tance in rice with toothpick inoculation method. A total of three sheath blight resis-tance-associated QTLs （qsb8-1, qsb8-2 and qsb8-3） were identified, which were lo-cated on adjacent molecular markers RM3262, RM5485 and RM3496 of chromo-some 8; the genetic interval was 81.7cM-91.7cM, 91.7cM-108.1cM and 108.1cM-119.6cM, respectively. The additive effect of qsb8-2 was negative, indicating that sheath blight resistance of susceptible parent harboring qsb8-2 fragment was en-hanced; additive effects of qsb8-1 and qsb8-3 were positive, indicating that sheath blight resistance of susceptible parent harboring qsb8-1 and qsb8-3 fragments was reduced.展开更多
Chromosome segment substitution lines（CSSLs） are useful for the precise mapping of quantitative trait loci（QTLs） and dissection of the genetic basis of complex traits.In this study,two whole-genome sequenced rice ...Chromosome segment substitution lines（CSSLs） are useful for the precise mapping of quantitative trait loci（QTLs） and dissection of the genetic basis of complex traits.In this study,two whole-genome sequenced rice cultivars,the japonica Nipponbare and indica 9311 were used as recipient and donor,respectively.A population with 57 CSSLs was developed after crossing and back-crossing assisted by molecular markers, and genotypes were identified using a high-throughput resequencing strategy.Detailed graphical genotypes of 38 lines were constructed based on resequencing data.These CSSLs had a total of 95 substituted segments derived from indica 9311,with an average of about 2.5 segments per CSSL and eight segments per chromosome,and covered about 87.4%of the rice whole genome.A multiple linear regression QTL analysis mapped four QTLs for 1000-grain weight.The largest-effect QTL was located in a region on chromosome 5 that contained a cloned major QTL GW5/qSW5 for grain size in rice.These CSSLs with a background of Nipponbare may provide powerful tools for future whole-genome展开更多
Rice kernel shape affects kernel quality(appearance) and yield(1000-kernel weight) and therefore is an important agronomic trait, but its inheritance is complicated. We identified a long-kernel rice chromosome segment...Rice kernel shape affects kernel quality(appearance) and yield(1000-kernel weight) and therefore is an important agronomic trait, but its inheritance is complicated. We identified a long-kernel rice chromosome segment substitution line(CSSL), Z741, derived from Nipponbare as a recipient and Xihui 18 as a donor parent. Z741 has six substitution segments distributed on rice chromosomes 3, 6, 7, 8 and 12 with an average replacement length of 5.82 Mb. Analysis of a secondary F2 population from a cross between Nipponbare and Z741 identified 20 QTLs for important agronomic traits. The kernel length of Z741 is controlled by a major QTL(qKL3) and a minor QTL(qKL7). Candidate gene prediction and sequencing indicated that qKL3 may be an allele of OsPPKL1, which encodes a protein phosphatase implicated in brassinosteroid signaling, and qKL7 is an unreported QTL. Finally, we validated eight QTLs(qKL3, qKL7, qRLW3-1, qRLW7, qPH3-1, qKWT3, qKWT7 and qNPB6) using three selected singlesegment substitution lines(SSSLs), S1, S2 and S3. Also, we detected five QTLs(qKL6, qKW3, qKW7, qKW6 and qRLW6) in S1, S2 and S3, which were not found in the Nipponbare/Z741 F2 population. However, qNPB3, qNPB7 and qPL3 QTLs were not validated by the three SSSLs in 2019, suggesting that minor QTLs are susceptible to environmental factors. These results lay the foundation for studying the biodiversity of kernal length and molecular breeding of different kernel types.展开更多
Diabetic macular edema(DME) is the most common cause of vision loss in diabetic retinopathy,affecting 1 in 15 patients with diabetes mellitus(DM).The disruption of the inner blood-retina barrier(BRB) has been largely ...Diabetic macular edema(DME) is the most common cause of vision loss in diabetic retinopathy,affecting 1 in 15 patients with diabetes mellitus(DM).The disruption of the inner blood-retina barrier(BRB) has been largely investigated and attributed the primary role in the pathogenesis and progression in DME, but there is increasing evidence regarding the role of outer BRB, separating the RPE from the underlying choriocapillaris,in the occurrence and evolution of DME.The development of novel imaging technologies has led to major improvement in the field of in vivo structural analysis of the macula allowing us to delve deeper into the pathogenesis of DME and expanding our vision regarding this condition.In this review we gathered the results of studies that investigated specific outer BRB optical coherence tomography parameters in patients with DM with the aim to outline the current status of its role in the pathogenesis and progression of DME and identify new research pathways contributing to the advancement of knowledge in the understanding of this condition.展开更多
Single segment substitution lines （SSSLs） each with a single chromosome segment from a donor under the same genetic background as the recipient were developed in rice by advanced backcrossing and molecular marker-as...Single segment substitution lines （SSSLs） each with a single chromosome segment from a donor under the same genetic background as the recipient were developed in rice by advanced backcrossing and molecular marker-assisted selection. Using the SSSLs, the QTLs for the important agronomic traits in rice would be detected under different environmental conditions. Detection of the QTLs controlling 22 important traits in rice was done with 32 SSSLs by the randomized block design in 2-4 cropping seasons. 59 QTLs were detected and distributed on chromosomes 1, 2, 3, 4, 6, 7, 8, 10, and 11, of which 18 QTLs were detected more than twice. Only 30.5% of the QTLs were detected repeatedly in different cropping seasons. Most of the QTLs of important agronomic traits were of little additive effects and instability. The QTLs controlling the traits, such as grain weight, grain length, ratio of grain length to width, and heading date were relatively stable. The stable QTLs usually had larger additive effects and were less affected by environment. The QTLs for the important agronomic traits were detected using the SSSLs in rice with high resolution under different environmental conditions. The instability of the QTLs may be the basis of the variation of rice plants during growth and development. It would be the genetic basis for improving yield and quality in rice cultivars by farming methods.展开更多
Tiller is one of the most important agronomic traits which influences quantity and quality of effective panicles and finally influences yield in rice. It is important to understand ＂static＂ and ＂dynamic＂ informati...Tiller is one of the most important agronomic traits which influences quantity and quality of effective panicles and finally influences yield in rice. It is important to understand ＂static＂ and ＂dynamic＂ information of the QTLs for tillers in rice. This work was the first time to simultaneously map unconditional and conditional QTLs for tiller numbers at various stages by using single segment substitution lines in rice. Fourteen QTLs for tiller number, distributing on the corresponding substitution segments of chromosomes 1, 2, 3, 4, 6, 7 and 8 were detected. Both the number and the effect of the QTLs for tiller number were various at different stages, from 6 to 9 in the number and from 1.49 to 3.49 in the effect, respectively. Tiller number QTLs expressed in a time order, mainly detected at three stages of 0-7 d, 14-21 d and 35-42 d after transplanting with 6 positive, 9 random and 6 negative expressing QTLs, respectively. Each of the QTLs expressed one time at least during the whole duration of rice. The tiller number at a specific stage was determined by sum of QTL effects estimated by the unconditional method, while the increasing or decreasing number in a given time interval was controlled by the total of QTL effects estimated by the conditional method. These results demonstrated that it is highly effective and accurate for mapping of the QTLs by using single segment substitution lines and the conditional analysis methodology.展开更多
QTLs for plant height and its components on the substituted segments of fifty-two single segment substitution lines （SSSLs） in rice were identified through t-test （P〈0.001） for comparison between each SSSL and re...QTLs for plant height and its components on the substituted segments of fifty-two single segment substitution lines （SSSLs） in rice were identified through t-test （P〈0.001） for comparison between each SSSL and recipient parent Huajingxian 74. On the 14 substituted segments, 24 QTLs were detected, 10 for plant height, 2 for panicle length, 4 for length of the first internode from the top, 5 for length of the second internode from the top and 3 for length of the third internode from the top, respectively. All these QTLs were distributed on nine rice chromosomes except chromosomes 5, 9 and 11. The additive effect ranged from -4.08 to 3.98 cm, and the additive effect percentages varied from -19.35% to 10.43%.展开更多
基金supported by the National Natural Science Foundation of China(No.52008308).
文摘When only a portion of the shield lining structures in a full-line tunnel are overloaded,their bearing and failure characteristics are significantly different from those in the full-line overloaded case.In existing studies,one or several segmental lining rings have been studied,with overload applied to selected lining rings to analyze the performance evolution of the lining structures;however,this approach fails to reveal the bearing and failure characteristics of shield lining rings under localized overload.To address this research gap,we employ 3D finite element modeling to investigate the mechanical performance and failure mechanisms of shield segmental linings under localized overload conditions,and compare the results with full-line overload scenarios.Additionally,the impact of reinforcing shield segmental linings with steel rings is studied to address issues arising from localized overloads.The results indicate that localized overloads lead to significant ring joint dislocation and higher stress on longitudinal bolts,potentially causing longitudinal bolt failure.Furthermore,the overall deformation of lining rings,segmental joint opening,and stress in circumferential bolts and steel bars is lower compared to full-line overloads.For the same overload level,the convergence deformation of the lining under full-line overload is 1.5 to 2.0 times higher than that under localized overload.For localized overload situations,a reinforcement scheme with steel rings spanning across two adjacent lining rings is more effective than installing steel rings within individual lining rings.This spanning ring reinforcement strategy not only enhances the structural rigidity of each ring,but also limits joint dislocation and reduces stress on longitudinal bolts,with the reduction in maximum ring joint dislocation ranging from 70%to 82%and the reduction in maximum longitudinal bolt stress ranging from 19%to 57%compared to reinforcement within rings.
基金supported by the National Natural Science Foundation of China(Nos.51938005,52090082,and 52378395)the National Key Research and Development Program of China(No.2023YFB2604402).
文摘This study aims to assess the comprehensive strengthening effect of a steel-ultra high performance concrete(UHPC)composite strengthening method.The axial force-moment interaction curve(N-M curve)was calculated in a novel way,using cross-sectional strains at ultimate states as well as real-time stress measurements for each material.The enclosed area of the N-M curve was defined as a comprehensive performance index for the system.We validate our approach with comparisons to numerical modeling and full-scale four-point bending experiments.Additionally,strengthening effects were compared for different sagging and hogging moments based on material stress responses,and the impact of various strengthening parameters was analyzed.We find that the N-M curve of the strengthened cross-section envelops that of the un-strengthened cross-section.Notably,improvements in flexural capacity are greater under sagging moments during the large eccentric failure stage,and greater under hogging moments during the small eccentric failure stage.This discrepancy is attributed to the strength utilization of strengthening materials.These findings provide a reference for understanding the strengthening effects and parameters of steel-UHPC composite.
基金Joint Funds of National Natural Science Foundation of China(No.U1134208)National Key Basic Research Program of China(No.2010CB732105)National Natural Science Foundation of China(No.50925830,No.51208432)
文摘Based on the first unde rwater railway shield tunnel, the Shiziyang shield tunnel of Guangzhou Zhu- jiang River, the prototype test was carried out against its segmental lining structure by using ＂multi-function shield tunnel structure test system＂. And the mechanical characteristics of segmental lining structure using straight assembling and staggered assembling were studied deeply. The results showed that, the mechanical characteristics of segmental lining structure varied with the water pressures; especially after cracking, the high water pressure played a significant role in slowing down the growing inner force and deformation. It also testi- fied that the failure characteristics varied with straight assembling structure and staggered assembling structure. Shear thilurc often occurred near longitudinal seam when using straight assembling.
基金sponsored by the Natural Science Foundation of China(Grant No.51008082)
文摘The uniform ring model and the shell-spring model for segmental lining design are reviewed in thisarticle. The former is the most promising means to reflect the real behavior of segmental lining, while thelatter is the most popular means in practice due to its simplicity. To understand the relationship and thedifference between these two models, both of them are applied to the engineering practice of FuzhouMetro Line I, where the key parameters used in both models are described and compared. The effectiveratio of bending rigidity h reflecting the relative stiffness between segmental lining and surroundingground and the transfer ratio of bending moment x reflecting the relative stiffness between segment andjoint, which are two key parameters used in the uniform ring model, are especially emphasized. Thereasonable values for these two key parameters are calibrated by comparing the bending momentscalculated from both two models. Through case studies, it is concluded that the effective ratio of bendingrigidity h increases significantly with good soil properties, increases slightly with increasing overburden,and decreases slightly with increasing water head. Meanwhile, the transfer ratio of bending moment xseems to only relate to the properties of segmental lining itself and has a minor relation with the groundconditions. These results could facilitate the design practice for Fuzhou Metro Line I, and could alsoprovide some references to other projects with respect to similar scenarios.
基金the National Natural Science Foundation of China(No.41372276)the Shanghai SASAC Technology Innovation and Energy Level Promotion Project(No.2013017)
文摘A series of full-scale loading tests are performed for a prospective subway tunnel with a rectangular shape including two reliability tests: one stagger-jointed three-ring reliability test, and one ultimate failure test on a single ring. Comprehensive measuring programs are designed to record the deformation of both lining structure and joints and the stresses of concrete, bolts and reinforcements. Experimental results show that in both the single-ring and three-ring loading cases, the long sides of tunnel cross section bend inwards while the short sides of tunnel cross section bend outwards. The inner part of joints opens while the outer part of joints closes at places experiencing positive moment and vice versa. Joint's rotational stiffness varies at different locations. Concrete cracking and crushing are the chief damage modes, and they are closely related to the distribution of bending moment. Stagger-jointed fabrication significantly increases the overall rigidity of lining system, which thereby greatly reduces the deformation of both concrete lining and joints in comparison with the single-ring case. It is shown that the routinely-used uniform rigidity model is conservative and the preliminary design can be optimized by applying an effective rigidity ratio(ERR) of 0.5.
基金supported by the National Natural Science Foundation of China(32172064)。
文摘Introducing the inherent genetic diversity of wild species into cultivars has become one of the hot topics in crop genetic breeding and genetic resource research.Fiber-and seed-related traits,which are critical to the global economy and people's livelihoods,are the principal focus of cotton breeding.Here,the wild cotton species Gossypium tomentosum was used to broaden the genetic basis of G.hirsutum and identify QTLs for fiber-and seed-related traits.A population of 559 chromosome segment substitution lines(CSSLs)was established with various chromosome segments from G.tomentosum in a G.hirsutum cultivar background.Totals of 72,89,and 76 QTLs were identified for three yield traits,five fiber quality traits,and six cottonseed nutrient quality traits,respectively.Favorable alleles of 104 QTLs were contributed by G.tomentosum.Sixty-four QTLs were identified in two or more environments,and candidate genes for three of them were further identified.The results of this study contribute to further studies on the genetic basis of the morphogenesis of these economic traits,and indicate the great breeding potential of G.tomentosum for improving the fiber-and seed-related traits in G.hirsutum.
基金supported by the Zhejiang Provincial Natural Science Foundation of China(Grant Nos.LZ24C130004 and LQ24C130008)。
文摘Heading date is one of the most important agronomic traits that directly affect rice yield and determines the regional adaptability in specific growing environments.As a short-day plant,rice can grow under long-day(LD)conditions due to the synergistic regulation of many photosensitive genes.Using a set of chromosome segment substitution lines(CSSLs)with the indica cultivar Huanghuazhan(HHZ)as the recipient parent and Basmati Surkh 89-15(BAS)as the donor parent,we identified a QTL locus.
基金supported by the National Natural Science Foundation of China [Grant No. 61674016]Beijing Municipality Excellent Talents Training Assistance (Young Backbone Individuals) Project [No. 2017000020124G071]in part by the State Key Development Program for Basic Research of China (973 Program) [Grant 2015CB057201]。
文摘With the continuous growth of signal frequency and package density, discontinuity of the high-frequency interconnection in 3 D micro/nano integration becomes unavoidable, which results in serious signal integrity problems. Traditional interconnection design schemes, such as termination and shielding/isolation, cannot meet the requirements under the unified constraints of specific cost, space occupancy, and performance. In this study, a transmission line design optimization scheme based on the segmental transmission line(STL) methodology is proposed. The genetic algorithm is used to select the optimal segment structure parameters of the transmission line to construct an STL with satisfying transmission performance or meet the specific signal amplitude adjustment requirements. This scheme can be adapted to various signal transmission scenarios to significantly improve the signal loss caused by reflection or other negative electromagnetic factors and meet the requirements for the modeling of discontinuous transmission lines. The simulation results show that this scheme is effective in the design scenario of performance improvement or equivalent modeling of discontinuous transmission lines and has significant advantages in circuit area reduction.
基金funded by the Deutsche Forschungsgemeinschaft(DFG,German Research Foundation,Project No.77309832)within Subprojects C1 and B2 of the Collaborative Research Center SFB 837"Interaction Modeling in Mechanised Tunnelling",sited at the Ruhr University Bochum,Germany.
文摘Over the last decades,an expansion of the underground network has been taking place to cope with the increasing amount of moving people and freight.As a consequence,it is of vital importance to guarantee the full functionality of the tunnel network by means of preventive maintenance and the monitoring of the tunnel lining state over time.A new method has been developed for the real-time prediction of the utilization level in tunnel segmental linings based on input monitoring data.The new concept is founded on a framework,which encompasses an offline and an online stage.In the former,the generation of feedforward neural networks is accomplished by employing synthetically produced data.Finite element simulations of the lining structure are conducted to analyze the structural response under multiple loading conditions.The scenarios are generated by assuming ranges of variation of the model input parameters to account for the uncertainty due to the not fully determined in situ conditions.Input and target quantities are identified to better assess the structural utilization of the lining.The latter phase consists in the application of the methodological framework on input monitored data,which allows for a real-time prediction of the physical quantities deployed for the estimation of the lining utilization.The approach is validated on a full-scale test of segmental lining,where the predicted quantities are compared with the actual measurements.Finally,it is investigated the influence of artificial noise added to the training data on the overall prediction performances and the benefits along with the limits of the concept are set out.
基金the financial support provided by the National Key Basic Research Program of China(No.2015CB057801)the Projects of the Construction Department of Zhejiang Province(Nos.2022K073 and 2022K169).
文摘Segmental tunnel lining strengthened with steel plates is widely used worldwide to provide a permanent strengthening method.Most existing studies assume an ideal steel-concrete interface,ignoring discontinuous deformation characteristics,making it difficult to accurately analyze the strengthened structure’s failure mechanism.In this study,interfacial fracture mechanics of composite material was applied to the segmental tunnel lining strengthened with steel plates,and a numerical three-dimensional solid nonlinear model of the lining structure was established,combining the extended finite element method with a cohesive-zone model to account for the discontinuous deformation characteristics of the interface.The results accurately describe the crack propagation process,and are verified by full-scale testing.Next,dynamic simulations based on the calibrated model were conducted to analyze the sliding failure and cracking of the steel-concrete interface.Lastly,detailed location of the interface bonding failure are further verified by model test.The results show that,the cracking failure and bond failure of the interface are the decisive factors determining the instability and failure of the strengthened structure.The proposed numerical analysis is a major step forward in revealing the interface failure mechanism of strengthened composite material structures.
基金Supported by National Natural Science Foundation of China(31101131)National Key Technology Research and Development Program(2011BAD16B03)+1 种基金Agricultural Science Independent Innovation Foundation of Jiangsu Province[CX(12)1003]Key Technology Research and Development Program of Jiangsu Province(BE2012309)~~
文摘Grain weight, one of the major factors determining rice yield, is a typical quantitative trait control ed by multiple genes. With Guangluai 4 as recipient and Nipponbare as donor, a population of 119 chromosome single segment substitution lines had been developed. Correlation analysis between grain weight and grain shape by SPSS revealed that 1 000-grain weight shared extremely significant posi-tive correlation with grain length and length-width ratio, but no significant correlation with grain width and thickness. The QTL analysis of grain weight was carried out using one-way analysis of variance and Dunnett＇s test. Nineteen stable QTLs re-sponsible for grain weight were identified over two years. Al 19 QTLs were identi-fied on al chromosomes except for chromosome 10 and 12 at a significance level of P≤0.001. Among them, 10 QTLs had a positive effect and were derived from the Nipponbare al ele, the additive effect of these QTLs ranged from 0.49 to 2.74 g, and the contributions of the additive effects ranged from 2.00% to 11.05%. Another 9 QTLs had a negative effect and were al derived from Guangluai 4 al ele, the ad-ditive effect of these QTLs ranged from 0.60 to 2.35 g, and the contributions of the additive effects ranged from 2.40% to 9.84%. The results provide a basis for the fine mapping and gene cloning of novel locus associated with rice grain weight.
基金Supported by National Natural Science Foundation of China (No. 10902073)
文摘To investigate the mechanical behavior of segmental lining, a three-dimensional numerical analysis and test using three actual segments were used to analyze the effects of axial force and reinforcement ratio on the failure mechanism and ultimate bearing capacity of segmental lining. Both numerical and test results confirmed that the cracking load, yield and ultimate load were strongly influenced by axial force, and it was also proved that the yield and ultimate load would increase with the increase of reinforcement ratio, but the cracking load was almost not affected. The cracking load, yield and ultimate load are about 28.7%, 500% and 460% larger due to the effect of axial force respectively. The comparison between numerical calculation and test results showed that the finite element analysis resuits were in good agreement with the test results.
文摘In this study, a population of chromosome segment substitution lines （CSSLs） derived from the cross between 9311 （indica） and Nipponbare （japonica） was employed to map the quantitative trait loci （QTLs） for salt tolerance under the salt stress simulated with 0.5% NaCI, using survival rate as the index. The data were analyzed by QTL IciMapping v3.1, and the results showed that one QTL （QSsr3） related to salt tolerance was located in the vicinity of the marker RM1350 on chromosome 3, into a genetic interval of 113.2-132.8 cM, with a contribution rate of 17.75%. The additive effect was 10.9, indicating that the QTL derived from the parent Nipponbare improved the salt tolerance of rice at seedling stage. This study will provide a theoretical basis for the selection of salt tolerant rice germplasm.
基金Supported by Specific Fund for the Independent Innovation of Agricultural Science and Technology[CX(11)1020]~~
文摘In this study, a population of 119 chromosome segment substitution lines （CSSLs） derived from backcross between indica 9311 and japonica Nipponbare was employed to map quantitative trait loci （QTL） associated with sheath blight resis-tance in rice with toothpick inoculation method. A total of three sheath blight resis-tance-associated QTLs （qsb8-1, qsb8-2 and qsb8-3） were identified, which were lo-cated on adjacent molecular markers RM3262, RM5485 and RM3496 of chromo-some 8; the genetic interval was 81.7cM-91.7cM, 91.7cM-108.1cM and 108.1cM-119.6cM, respectively. The additive effect of qsb8-2 was negative, indicating that sheath blight resistance of susceptible parent harboring qsb8-2 fragment was en-hanced; additive effects of qsb8-1 and qsb8-3 were positive, indicating that sheath blight resistance of susceptible parent harboring qsb8-1 and qsb8-3 fragments was reduced.
基金supported in part by the National Basic Research Program(Nos.2012CB944803 and 2011CB 100202)the National Natural Science Foundation(No.31071383)+1 种基金the National Special Program for Transgenic Research(No. 2009ZX08009-008B)the Priority Academic Program Development from Jiangsu Government of China
文摘Chromosome segment substitution lines（CSSLs） are useful for the precise mapping of quantitative trait loci（QTLs） and dissection of the genetic basis of complex traits.In this study,two whole-genome sequenced rice cultivars,the japonica Nipponbare and indica 9311 were used as recipient and donor,respectively.A population with 57 CSSLs was developed after crossing and back-crossing assisted by molecular markers, and genotypes were identified using a high-throughput resequencing strategy.Detailed graphical genotypes of 38 lines were constructed based on resequencing data.These CSSLs had a total of 95 substituted segments derived from indica 9311,with an average of about 2.5 segments per CSSL and eight segments per chromosome,and covered about 87.4%of the rice whole genome.A multiple linear regression QTL analysis mapped four QTLs for 1000-grain weight.The largest-effect QTL was located in a region on chromosome 5 that contained a cloned major QTL GW5/qSW5 for grain size in rice.These CSSLs with a background of Nipponbare may provide powerful tools for future whole-genome
基金supported by the National Key Research Plan Project of China(Grant No.2017YFD0101107)Chongqing Technical Innovation and Application Development Project(Grant No.cstc2019jscx-msxmX0392)。
文摘Rice kernel shape affects kernel quality(appearance) and yield(1000-kernel weight) and therefore is an important agronomic trait, but its inheritance is complicated. We identified a long-kernel rice chromosome segment substitution line(CSSL), Z741, derived from Nipponbare as a recipient and Xihui 18 as a donor parent. Z741 has six substitution segments distributed on rice chromosomes 3, 6, 7, 8 and 12 with an average replacement length of 5.82 Mb. Analysis of a secondary F2 population from a cross between Nipponbare and Z741 identified 20 QTLs for important agronomic traits. The kernel length of Z741 is controlled by a major QTL(qKL3) and a minor QTL(qKL7). Candidate gene prediction and sequencing indicated that qKL3 may be an allele of OsPPKL1, which encodes a protein phosphatase implicated in brassinosteroid signaling, and qKL7 is an unreported QTL. Finally, we validated eight QTLs(qKL3, qKL7, qRLW3-1, qRLW7, qPH3-1, qKWT3, qKWT7 and qNPB6) using three selected singlesegment substitution lines(SSSLs), S1, S2 and S3. Also, we detected five QTLs(qKL6, qKW3, qKW7, qKW6 and qRLW6) in S1, S2 and S3, which were not found in the Nipponbare/Z741 F2 population. However, qNPB3, qNPB7 and qPL3 QTLs were not validated by the three SSSLs in 2019, suggesting that minor QTLs are susceptible to environmental factors. These results lay the foundation for studying the biodiversity of kernal length and molecular breeding of different kernel types.
文摘Diabetic macular edema(DME) is the most common cause of vision loss in diabetic retinopathy,affecting 1 in 15 patients with diabetes mellitus(DM).The disruption of the inner blood-retina barrier(BRB) has been largely investigated and attributed the primary role in the pathogenesis and progression in DME, but there is increasing evidence regarding the role of outer BRB, separating the RPE from the underlying choriocapillaris,in the occurrence and evolution of DME.The development of novel imaging technologies has led to major improvement in the field of in vivo structural analysis of the macula allowing us to delve deeper into the pathogenesis of DME and expanding our vision regarding this condition.In this review we gathered the results of studies that investigated specific outer BRB optical coherence tomography parameters in patients with DM with the aim to outline the current status of its role in the pathogenesis and progression of DME and identify new research pathways contributing to the advancement of knowledge in the understanding of this condition.
基金the National Natural Science Foundation of China （30330370）.
文摘Single segment substitution lines （SSSLs） each with a single chromosome segment from a donor under the same genetic background as the recipient were developed in rice by advanced backcrossing and molecular marker-assisted selection. Using the SSSLs, the QTLs for the important agronomic traits in rice would be detected under different environmental conditions. Detection of the QTLs controlling 22 important traits in rice was done with 32 SSSLs by the randomized block design in 2-4 cropping seasons. 59 QTLs were detected and distributed on chromosomes 1, 2, 3, 4, 6, 7, 8, 10, and 11, of which 18 QTLs were detected more than twice. Only 30.5% of the QTLs were detected repeatedly in different cropping seasons. Most of the QTLs of important agronomic traits were of little additive effects and instability. The QTLs controlling the traits, such as grain weight, grain length, ratio of grain length to width, and heading date were relatively stable. The stable QTLs usually had larger additive effects and were less affected by environment. The QTLs for the important agronomic traits were detected using the SSSLs in rice with high resolution under different environmental conditions. The instability of the QTLs may be the basis of the variation of rice plants during growth and development. It would be the genetic basis for improving yield and quality in rice cultivars by farming methods.
基金supported by the grants from the National.Basic Research Program of China(2006CB 101700)the National Natural Science Foundation of China(30330370).
文摘Tiller is one of the most important agronomic traits which influences quantity and quality of effective panicles and finally influences yield in rice. It is important to understand ＂static＂ and ＂dynamic＂ information of the QTLs for tillers in rice. This work was the first time to simultaneously map unconditional and conditional QTLs for tiller numbers at various stages by using single segment substitution lines in rice. Fourteen QTLs for tiller number, distributing on the corresponding substitution segments of chromosomes 1, 2, 3, 4, 6, 7 and 8 were detected. Both the number and the effect of the QTLs for tiller number were various at different stages, from 6 to 9 in the number and from 1.49 to 3.49 in the effect, respectively. Tiller number QTLs expressed in a time order, mainly detected at three stages of 0-7 d, 14-21 d and 35-42 d after transplanting with 6 positive, 9 random and 6 negative expressing QTLs, respectively. Each of the QTLs expressed one time at least during the whole duration of rice. The tiller number at a specific stage was determined by sum of QTL effects estimated by the unconditional method, while the increasing or decreasing number in a given time interval was controlled by the total of QTL effects estimated by the conditional method. These results demonstrated that it is highly effective and accurate for mapping of the QTLs by using single segment substitution lines and the conditional analysis methodology.
基金the key project ofNational Natural Science Foundation of China(30330370) the team project of Natural ScienceFoundation of Guangdong Province (20003023).
文摘QTLs for plant height and its components on the substituted segments of fifty-two single segment substitution lines （SSSLs） in rice were identified through t-test （P〈0.001） for comparison between each SSSL and recipient parent Huajingxian 74. On the 14 substituted segments, 24 QTLs were detected, 10 for plant height, 2 for panicle length, 4 for length of the first internode from the top, 5 for length of the second internode from the top and 3 for length of the third internode from the top, respectively. All these QTLs were distributed on nine rice chromosomes except chromosomes 5, 9 and 11. The additive effect ranged from -4.08 to 3.98 cm, and the additive effect percentages varied from -19.35% to 10.43%.
