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经济增长中的“不定性”——经济增长中复杂性的体现 被引量:2
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作者 邹恒甫 龚六堂 张晏 《经济学动态》 CSSCI 北大核心 2002年第1期73-78,共6页
人类社会发展到21世纪,科技、文化、经济和社会生活水平也进入了前所未有的崭新阶段。人类几千年的文明历史积聚了巨大的财富,但稍作统计我们就会发现,这些财富的大部分都集中在美国等发达资本主义国家。如果说是不同的历史和文化背景... 人类社会发展到21世纪,科技、文化、经济和社会生活水平也进入了前所未有的崭新阶段。人类几千年的文明历史积聚了巨大的财富,但稍作统计我们就会发现,这些财富的大部分都集中在美国等发达资本主义国家。如果说是不同的历史和文化背景影响了不同国家的经济发展水平,但是,我们也注意到很多具有相似历史和文化背景的国家和地区,也表现出不同的发展势头。更为奇怪的是。 展开更多
关键词 经济增长 “不定性” Kura模型 Lucas 生产函数 效用函数
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Semi-analytical solution for mechanical analysis of tunnels crossing strike-slip fault zone considering nonuniform fault displacement and uncertain fault plane position
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作者 YANG Heng-hong WANG Ming-nian +1 位作者 YU Li ZHANG Xiao 《Journal of Central South University》 SCIE EI CAS CSCD 2024年第6期2116-2136,共21页
The tunnel subjected to strike-slip fault dislocation exhibits severe and catastrophic damage.The existing analysis models frequently assume uniform fault displacement and fixed fault plane position.In contrast,post-e... The tunnel subjected to strike-slip fault dislocation exhibits severe and catastrophic damage.The existing analysis models frequently assume uniform fault displacement and fixed fault plane position.In contrast,post-earthquake observations indicate that the displacement near the fault zone is typically nonuniform,and the fault plane position is uncertain.In this study,we first established a series of improved governing equations to analyze the mechanical response of tunnels under strike-slip fault dislocation.The proposed methodology incorporated key factors such as nonuniform fault displacement and uncertain fault plane position into the governing equations,thereby significantly enhancing the applicability range and accuracy of the model.In contrast to previous analytical models,the maximum computational error has decreased from 57.1%to 1.1%.Subsequently,we conducted a rigorous validation of the proposed methodology by undertaking a comparative analysis with a 3D finite element numerical model,and the results from both approaches exhibited a high degree of qualitative and quantitative agreement with a maximum error of 9.9%.Finally,the proposed methodology was utilized to perform a parametric analysis to explore the effects of various parameters,such as fault displacement,fault zone width,fault zone strength,the ratio of maximum fault displacement of the hanging wall to the footwall,and fault plane position,on the response of tunnels subjected to strike-slip fault dislocation.The findings indicate a progressive increase in the peak internal forces of the tunnel with the rise in fault displacement and fault zone strength.Conversely,an augmentation in fault zone width is found to contribute to a decrease in the peak internal forces.For example,for a fault zone width of 10 m,the peak values of bending moment,shear force,and axial force are approximately 46.9%,102.4%,and 28.7% higher,respectively,compared to those observed for a fault zone width of 50 m.Furthermore,the position of the peak internal forces is influenced by variations in the ratio of maximum fault displacement of the hanging wall to footwall and the fault plane location,while the peak values of shear force and axial force always align with the fault plane.The maximum peak internal forces are observed when the footwall exclusively bears the entirety of the fault displacement,corresponding to a ratio of 0:1.The peak values of bending moment,shear force,and axial force for the ratio of 0:1 amount to approximately 123.8%,148.6%,and 111.1% of those for the ratio of 0.5:0.5,respectively. 展开更多
关键词 strike-slip fault tunnel engineering semi-analytical solution fault zone width nonuniform fault displacement uncertain fault plane position
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重庆市工程岩体分级讨论 被引量:8
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作者 何沛田 崔洪业 张丽 《地下空间》 CSCD 2002年第3期274-277,共4页
本文针对重庆市岩石地基的特点 ,在简单介绍《工程岩体分级标准》的基本质量分级方法后 。
关键词 重庆 工程岩体 定性分级 定量分级 “不定性”因素
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Effect of quality uncertainty of parts on performance of reprocessing system in remanufacturing environment 被引量:5
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作者 汤希峰 毛海军 李旭宏 《Journal of Southeast University(English Edition)》 EI CAS 2011年第1期92-95,共4页
Aimed at the problem of stochastic routings for reprocessing operations and highly variable processing times,an open queuing network is utilized to model a typical reprocessing system.In the model,each server is subje... Aimed at the problem of stochastic routings for reprocessing operations and highly variable processing times,an open queuing network is utilized to model a typical reprocessing system.In the model,each server is subject to breakdown and has a finite buffer capacity,while repair times,breakdown times and service time follow an exponential distribution.Based on the decomposition principle and the expansion methodology,an approximation analytical algorithm is proposed to calculate the mean reprocessing time,the throughput of each server and other parameters of the processing system.Then an approach to determining the quality of disassembled parts is suggested,on the basis of which the effect of parts quality on the performance of the reprocessing system is investigated.Numerical examples show that there is a negative correlation between quality of parts and their mean reprocessing time.Furthermore,marginal reprocessing time of the parts decrease with the drop in their quality. 展开更多
关键词 REMANUFACTURING UNCERTAINTY reprocessing system open queuing network
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Characterizing uncertainty in pavement performance prediction 被引量:2
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作者 孙璐 葛敏莉 +1 位作者 顾文钧 徐冰 《Journal of Southeast University(English Edition)》 EI CAS 2012年第1期85-93,共9页
Taking variability and uncertainty involved in performance prediction into account, in order to make the prediction reliable and meaningful, a distribution-based method is developed to predict future PSI. This method,... Taking variability and uncertainty involved in performance prediction into account, in order to make the prediction reliable and meaningful, a distribution-based method is developed to predict future PSI. This method, which is based on the AASHTO pavement performance model, treats predictor variables as random variables with certain probability distributions and obtains the distribution of future PSI through the method of Monte-Carlo simulation. A computer program PERFORM using Monte Carlo simulation is developed to implement the numerical computation. Simulation results based on pavement and traffic parameters show that traffic, surface layer material property, and initial pavement performance are the most significant factors affecting pavement performance. Once the distribution of future PSI is determined, statistics such as the mean and the variance of future PSI are readily available. 展开更多
关键词 pavement performance VARIABILITY PREDICTION Monte Carlo simulation
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Genetic Analysis and Mapping of Genes Involved in Fertility of Pingxiang Dominant Genic Male Sterile Rice 被引量:8
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作者 黄廷友 王玉平 +2 位作者 马炳田 马玉清 李仕贵 《Journal of Genetics and Genomics》 SCIE CAS CSCD 北大核心 2007年第7期616-622,共7页
Pingxiang-dominant genic male sterile rice (PDGMSR) was the first dominant genic male sterile mutant identified in rice (Oryza sativa L.), and the corresponding dominant genic male sterile gene was designated as M... Pingxiang-dominant genic male sterile rice (PDGMSR) was the first dominant genic male sterile mutant identified in rice (Oryza sativa L.), and the corresponding dominant genic male sterile gene was designated as Ms-p. The fertility of PDGMSR can be restored by introduction of a dominant epistatic fertility restoring gene in some rice varieties. In the present study, E823, an indica inbred rice variety, restored the fertility of PDGMSR, and the genetic pattern was found to be consistent with a dominant epistatic model, therefore, the dominant epistatic fertility restorer gene was designated as Rfe. The F2 population from the cross of PDGMSR/E823 was developed to map gene Rfe. The F2 plants with the genotypes Ms-pMs-pRferfe or Ms-pms-pRferfe were used to construct a fertile pool, and the corresponding sterile plants with genotypes Ms-pMs-prferfe or Ms-pms-prferfe were used to con- struct a sterile pool. The fertility restoring gene Rfe was mapped to one side of the microsatellite markers RM311 and RM3152 on rice chromosome 10, with genetic distances of 7.9 cM and 3.6 cM, respectively. The microsatellite markers around the location of the Ms-p gene were used to finely map the Ms-p gene. The findings of this study indicated that the microsatellite markers RM171 and RM6745 flanked the Ms-p gene, and the distances were 0.3 cM and 3.0 cM, respectively. On the basis of the sequence of rice chromosome 10, the physical distance between the two markers is approximately 730 kb. These findings facilitates molecular marker-assisted selection (MAS) of genes Ms-p and Rfe in rice breeding programs, and cloning them in the future. 展开更多
关键词 dominant epistatic fertility restoring gene dominant genic male sterile gene mapping PDGMSR
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ROBUST OPTIMIZATION OF AERODYNAMIC DESIGN USING SURROGATE MODEL 被引量:4
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作者 王宇 余雄庆 《Transactions of Nanjing University of Aeronautics and Astronautics》 EI 2007年第3期181-187,共7页
To reduce the high computational cost of the uncertainty analysis, a procedure is proposed for the aerodynamic optimization under uncertainties, in which the surrogate model is used to simplify the computation of the ... To reduce the high computational cost of the uncertainty analysis, a procedure is proposed for the aerodynamic optimization under uncertainties, in which the surrogate model is used to simplify the computation of the uncertainty analysis. The surrogate model is constructed by using the Latin Hypercube design and the Kriging model. The random parameters are used to account for the small manufacturing errors and the variations of operating conditions. Based on the surrogate model, an uncertainty analysis approach, called the Monte Carlo simulation, is used to compute the mean value and the variance of the predicated performance. The robust optimization for aerodynamic design is formulated, and solved by the genetic algorithm. And then, an airfoil optimization problem is used to test the proposed procedure. Results show that the optimal solutions obtained from the uncertainty-based optimization formulation are less sensitive to uncertainties. And the design constraints are still satisfied under the uncertainties. 展开更多
关键词 surrogate model UNCERTAINTY AIRFOIL aerodynamic optimization
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Dynamic analysis and experimental study of vibro-acoustic system with uncertainties at middle frequencies 被引量:2
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作者 焦仁强 张建润 薛飞 《Journal of Southeast University(English Edition)》 EI CAS 2017年第2期166-170,共5页
To take into account the influence of uncetainties on the dynamic response of the vibro-acousitc structure, a hybrid modeling technique combining the finite element method(FE)and the statistic energy analysis(SEA)... To take into account the influence of uncetainties on the dynamic response of the vibro-acousitc structure, a hybrid modeling technique combining the finite element method(FE)and the statistic energy analysis(SEA) is proposed to analyze vibro-acoustics responses with uncertainties at middle frequencies. The mid-frequency dynamic response of the framework-plate structure with uncertainties is studied based on the hybrid FE-SEA method and the Monte Carlo(MC)simulation is performed so as to provide a benchmark comparison with the hybrid method. The energy response of the framework-plate structure matches well with the MC simulation results, which validates the effectiveness of the hybrid FE-SEA method considering both the complexity of the vibro-acoustic structure and the uncertainties in mid-frequency vibro-acousitc analysis. Based on the hybrid method, a vibroacoustic model of a construction machinery cab with random properties is established, and the excitations of the model are measured by experiments. The responses of the sound pressure level of the cab and the vibration power spectrum density of the front windscreen are calculated and compared with those of the experiment. At middle frequencies, the results have a good consistency with the tests and the prediction error is less than 3. 5dB. 展开更多
关键词 hybrid finite element method and statistic energy analysis(FE-SEA) method dynamic analysis vibroacoustic system UNCERTAINTIES mid-frequency range
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A non-parametric indicator Kriging method for generating coastal sediment type map 被引量:2
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作者 刘付程 彭俊 张存勇 《Marine Science Bulletin》 2012年第1期57-67,共11页
Coastal sediment type map has been widely used in marine economic and engineering activities, but the traditional mapping methods had some limitations due to their intrinsic assumption or subjectivity. In this paper, ... Coastal sediment type map has been widely used in marine economic and engineering activities, but the traditional mapping methods had some limitations due to their intrinsic assumption or subjectivity. In this paper, a non-parametric indicator Kriging method has been proposed for generating coastal sediment map. The method can effectively avoid mapping subjectivity, has no special requirements for the sample data to meet second-order stationary or normal distribution, and can also provide useful information on the quantitative evaluation of mapping uncertainty. The application of the method in the southern sea area of Lianyungang showed that much more convincing mapping results could be obtained compared with the traditional methods such as IDW, Kriging and Voronoi diagram under the same condition, so the proposed method was applicable with great utilization value. 展开更多
关键词 sediment type non-parametric indicator Kriging UNCERTAINTY mapping
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Performance of bottleneck shifting for remanufacturing system considering returns' quality grading 被引量:1
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作者 郑玉巧 苏春 +1 位作者 曹白雪 施杨梅 《Journal of Southeast University(English Edition)》 EI CAS 2015年第4期516-521,共6页
Aimed at the remanufacturing system, the effect of the uncertainty of returns' quality on bottleneck shifting is investigated. A novel definition of bottleneck station is presented and the probability of a station be... Aimed at the remanufacturing system, the effect of the uncertainty of returns' quality on bottleneck shifting is investigated. A novel definition of bottleneck station is presented and the probability of a station becoming a bottleneck is also given. By calculating the effective output, the effective operation time (EOT) and the ratio of EOT of each station, the system's current bottleneck of effective output time is determined. By calculating the probability coefficient of variation and index of bottleneck shifting, the quantitative performance of bottleneck shifting is obtained. Discrete event simulation and the experiment design method are adopted to simulate the system, in which the proportion of quality grading, repair rates and process routes are considered. The case study shows that the uncertainty of returns' quality greatly increases the probability of bottleneck shifting, and with the increase of the discrete degree of the returns' repair rate, the bottleneck shifting phenomenon is more obvious. Furthermore, bottleneck shifting is closely related to the process route of the dominating returns' quality grade. 展开更多
关键词 bottleneck shifting REMANUFACTURING returns quality grading UNCERTAINTY
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Microsatellite Alterations on Chromosome 8 of Hepatocellular Carcinoma 被引量:1
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作者 张树辉 冼志红 +1 位作者 丛文铭 吴孟超 《The Chinese-German Journal of Clinical Oncology》 CAS 2004年第1期5-10,64,共7页
Objective: To study the features of microsatellite alterations on chromosome 8 and their asso- ciation with clinicopathological characteristics of hepatocellular carcinoma (HCC). Methods: Ten highly- ... Objective: To study the features of microsatellite alterations on chromosome 8 and their asso- ciation with clinicopathological characteristics of hepatocellular carcinoma (HCC). Methods: Ten highly- polymorphic microsatellite markers on chromosome 8 were selected to be detected for loss of heterozygosity (LOH), microsatellite instability (MSI) and allelic imbalance (AI) in 56 HCC using MegaBACE 500 auto- matic DNA analysis system. Results: LOH was found in 37 of 56 HCC (66.1%) on at least 1 locus, and the top three loci were D8S261(53.5%), D8S1721(52.5%) and D8S1771(52.5%). LOH frequency on D8S277 was signi?cantly higher in cases positive for serum HBsAg than in those negative for HBsAg (P <0.01). Similarly, LOH on D8S261, D8S298 and D8S1733 occurred more frequently in patients with negative HB- sAg than those with positive HBsAg (P <0.01). LOH on D8S298 and D8S1771 was more frequent in those tumors larger than 3 cm in size (P <0.05 or P <0.01). LOH frequencies of D8S1721 were signi?cantly higher in the patients with absent or not intact tumor capsule than in those with intact tumor capsule (P <0.05). LOH on D8S298 and D8S1771 was more frequently detected in tumors with intrahepatic metastasis than in those without intrahepatic metastasis (P <0.01). MSI was found in 12.5% (7/56) cases, and AI was found in 19.6% (11/56), no correlation was found between MSI and AI and clinicopathological character- istics of HCC. Conclusion: Frequent microsatellite alterations on chromosome 8 existed in HCC. LOH, which represents tumor suppressor gene pathway, plays a more important role in hepatocarcinogenesis; MSI representing mismatch repair gene pathway ranks next. LOH at a particula locus is associated with the clinicopathological parameters of human HCC. 展开更多
关键词 liver neoplasms carcinoma hepatocellular loss of heterozygosity microsatellite instability allelic imbalance
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Stability of finite difference numerical simulations of acoustic logging-while-drilling with different perfectly matched layer schemes 被引量:2
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作者 王华 陶果 +2 位作者 尚学峰 方鑫定 Daniel R Burns 《Applied Geophysics》 SCIE CSCD 2013年第4期384-396,510,511,共15页
In acoustic logging-while-drilling (ALWD) finite difference in time domain (FDTD) simulations, large drill collar occupies, most of the fluid-filled borehole and divides the borehole fluid into two thin fluid colu... In acoustic logging-while-drilling (ALWD) finite difference in time domain (FDTD) simulations, large drill collar occupies, most of the fluid-filled borehole and divides the borehole fluid into two thin fluid columns (radius -27 mm). Fine grids and large computational models are required to model the thin fluid region between the tool and the formation. As a result, small time step and more iterations are needed, which increases the cumulative numerical error. Furthermore, due to high impedance contrast between the drill collar and fluid in the borehole (the difference is 〉30 times), the stability and efficiency of the perfectly matched layer (PML) scheme is critical to simulate complicated wave modes accurately. In this paper, we compared four different PML implementations in a staggered grid finite difference in time domain (FDTD) in the ALWD simulation, including field-splitting PML (SPML), multiaxial PML(M- PML), non-splitting PML (NPML), and complex frequency-shifted PML (CFS-PML). The comparison indicated that NPML and CFS-PML can absorb the guided wave reflection from the computational boundaries more efficiently than SPML and M-PML. For large simulation time, SPML, M-PML, and NPML are numerically unstable. However, the stability of M-PML can be improved further to some extent. Based on the analysis, we proposed that the CFS-PML method is used in FDTD to eliminate the numerical instability and to improve the efficiency of absorption in the PML layers for LWD modeling. The optimal values of CFS-PML parameters in the LWD simulation were investigated based on thousands of 3D simulations. For typical LWD cases, the best maximum value of the quadratic damping profile was obtained using one do. The optimal parameter space for the maximum value of the linear frequency-shifted factor (a0) and the scaling factor (β0) depended on the thickness of the PML layer. For typical formations, if the PML thickness is 10 grid points, the global error can be reduced to 〈1% using the optimal PML parameters, and the error will decrease as the PML thickness increases. 展开更多
关键词 PML schemes FD simulation LWD acoustic
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Mapping of S-b Locus for F_1 Pollen Sterility in Cultivated Rice Using PCR Based Markers 被引量:13
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作者 李文涛 曾瑞珍 +1 位作者 张泽民 张桂权 《Acta Botanica Sinica》 CSCD 2002年第4期463-467,共5页
In cultivated rice ( Oryza sativa L.), F-1 pollen sterility is controlled by at least 6 loci of the F, pollen sterility genes. To map S-b, one of loci, rice variety Taichung 65 (T65) carrying S-b(j)/S-b(j) and its nea... In cultivated rice ( Oryza sativa L.), F-1 pollen sterility is controlled by at least 6 loci of the F, pollen sterility genes. To map S-b, one of loci, rice variety Taichung 65 (T65) carrying S-b(j)/S-b(j) and its near-isogenic line TIST2 carrying S-b(i)/S-b(i) were used to develop the mapping population. One hundred and fifty-eight microsatellite markers were selected to survey T65 and TISL2. RM13 on chromosome 5 was found to be polymorphic between them. Cosegregation indicated that RM13 was closely linked with locus S-b. Eleven RFLP markers were selected on the corresponding region from the genetic map of Rice Genome Research Program (RGP) of Japan to convert into sequence-tagged site (STS) markers. Amplicon length polymorphism (ALP) was carried out, but none of them was found to be polymorphic between T65 and TISL2. Then PCR-based RFLP (PBR) was done using six 4-nucleotide recognizing restriction endonucleases. Polymorphism was detected when PCR products of R830STS and R2213SSTS were digested with Taq I. Genetic analysis indicated that the distance between locus S-b and markers, R830STS, RM13 and R2213SSTS were 3.3 cM (centi-Morgan), 5.2 cM and 5.5 cM, respectively. These PCR-based markers could be directly used in marker-assisted selection. The technical system combining genetic mapping and PCR-based marker-assisted selection will facilitate the development of molecular breeding. 展开更多
关键词 F-1 pollen sterility genetic mapping MICROSATELLITE sequence-tagged site (STS) RICE
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Solvability Condition for Robust Stabilization Problem of Control Systems with Parameter Uncertainties 被引量:1
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作者 伍清河 《Journal of Beijing Institute of Technology》 EI CAS 1999年第3期258-263,共6页
Aim The solvability condition for robust stabilization problem associated with a plant family P(s,δ) having parameter uncertainty δ was considered. Methods Using Youla parameterization of the stabilizers this pro... Aim The solvability condition for robust stabilization problem associated with a plant family P(s,δ) having parameter uncertainty δ was considered. Methods Using Youla parameterization of the stabilizers this problem was transformed into a strong stabilization problem associated with a related plant family G (s, δ). Results A necessary solvability condition was established in terms of the parity interlacing property of each element in G(s,δ). Another apparently necessary solvability condition is that every element in P(s,δ) must be stabilizable. Conclusion The two conditions will be compared with each other and it will be shown that every element in G(s,δ) possesses parity interlacing property if P(s,δ) is stabilizable. 展开更多
关键词 robust stabilization parameter uncertainties strong stabilization parity interlacing property
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Molecular Markers and Agronomic Traits of a New Kind of Genic Male Sterile Material Mian 7AB-4-2 in Brassica napus L. 被引量:1
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作者 李浩杰 汤天泽 +4 位作者 袁代斌 蒙大庆 蒲晓斌 张锦芳 蒋梁材 《Agricultural Science & Technology》 CAS 2009年第1期60-63,152,共5页
[ Objective] The study was to investigate the agronomic traits and breeding characteristics of genic male sterile material Mian 7AB-4- 2 in Brassica napus. [ Method] The differences in agronomic traits and polymorphis... [ Objective] The study was to investigate the agronomic traits and breeding characteristics of genic male sterile material Mian 7AB-4- 2 in Brassica napus. [ Method] The differences in agronomic traits and polymorphisms in SSR markers, between the genic male sterile material Mian 7AB-4-2 in Brassica napus and its sisterly line Mian 7AB-4-1 were investigated by hybridization and molecular identification; and the percentage of sterile individuals of Mian 7AB-4-2 and of the hybrids with its sisterly line Mian 7AB-4-1 from test cross and back cross were also studled. [ Result] Mian 7AB-4-2 was not significantly different in agronomic traits from its sisterly line Mian 7AB-4-1 at 0.05 probability level. The per- centages of sterile individuals in the pollinated fertile Mian 7AB-4-2 plants were over 60%, and that in its sisterly line Mian 7AB-4-1 was about 25%. In test crosses with other nine sterile lines, Mian 7AB-4-1 kept the percentage of sterile individuals of sterile lines over 90%, and the percentage of sterile individuals from back cross over 80%. With regard to molecular markers, Mian 7AB-4-2 and its sisterly line Mian 7AB-4-1 were different in the band number from SSR primers a2 and E10. [ Conclusion] The results indicate that Mian 7AB-4-2 is helpful for rapeseed breeding, quickening the application of new materials in field breeding. 展开更多
关键词 Brassica napus L. Recessive genic male sterility Self-pollination of fertile individual Test cross Back cross SSR marker POLYMORPHISM
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Robust adaptive dynamic surface control for nonlinear uncertain systems 被引量:5
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作者 朱永红 姜长生 费树岷 《Journal of Southeast University(English Edition)》 EI CAS 2003年第2期126-131,共6页
We propose a new method for robust adaptive backstepping control of nonlinear systems with parametric uncertainties and disturbances in the strict feedback form. The method is called dynamic surface control. Traditio... We propose a new method for robust adaptive backstepping control of nonlinear systems with parametric uncertainties and disturbances in the strict feedback form. The method is called dynamic surface control. Traditional backstepping algorithms require repeated differentiations of the modelled nonlinearities. The addition of n first order low pass filters allows the algorithm to be implemented without differentiating any model nonlinearities, thus ending the complexity arising due to the 'explosion of terms' that makes other methods difficult to implement in practice. The combined robust adaptive backstepping/first order filter system is proved to be semiglobally asymptotically stable for sufficiently fast filters by a singular perturbation approach. The simulation results demonstrate the feasibility and effectiveness of the controller designed by the method. 展开更多
关键词 nonlinear systems robust control adaptive control dynamic surface control UNCERTAINTIES
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Studies on Thermo-sensitivity of Ningxia Hot Pepper Male Sterile Line 被引量:1
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作者 颜秀娟 何鑫 +2 位作者 张丽娟 王学梅 高晶霞 《Agricultural Science & Technology》 CAS 2014年第11期1908-1909,1918,共3页
[Objective] This study was conducted to identify the thermo-sensitivity of the male sterile line (NYB) of Ningxia hot pepper. [Method] The pol en abortion rates of pepper male sterile line under artificial y control... [Objective] This study was conducted to identify the thermo-sensitivity of the male sterile line (NYB) of Ningxia hot pepper. [Method] The pol en abortion rates of pepper male sterile line under artificial y control ed temperature condition and nature temperature condition were measured and compared. [Result] The pol en abortion was the sign of NYB male sterility. The pol en abortion rate changed little under different temperature conditions, while pol en amount greatly reduced at low temperature, indicating that NYB was genetical y stable in field. [Conclusion] The re-sults can provide some theoretical references for the application of NYB pepper male sterile line in breeding work. 展开更多
关键词 Pepper Male sterility Thermo-sensitivity Inheritance
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Research on Stability of Desert Climate of Minqin County in Gansu Province
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作者 常兆丰 王大为 +1 位作者 韩福贵 段晓峰 《Agricultural Science & Technology》 CAS 2015年第12期2833-2838,共6页
In order to study the stability of desert climate, the instability of climate in Minqin desert in response to global warming during 1961-2013 was analyzed by sliding standard deviation and a linear trend line. The res... In order to study the stability of desert climate, the instability of climate in Minqin desert in response to global warming during 1961-2013 was analyzed by sliding standard deviation and a linear trend line. The results show that the instabili- ty of average temperature in January and April increased, and the isothermal date in February was 10.36 d earlier from 1961 to 2013. The instability of extreme maxi- mum temperature in December and January improved. The instability of extreme minimum temperature in July instability also increased. The coefficient of variation of extreme minimum temperature in May was up to 287.3%. It is concluded that the instability of desert climate of Minqin County increased with global warming. The stability of climate is more worthy of attention. 展开更多
关键词 Global warming Desert climate INSTABILITY Minqin
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FURTHER OBSERVATIONS OF LATE TRANSITION PROCESSES IN CROSSFLOW INSTABILITY EXPERIMENT
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作者 吴永健 明晓 《Transactions of Nanjing University of Aeronautics and Astronautics》 EI 2000年第1期26-30,共5页
The experiments of primary and secondary instabilities with controlled excitation are carried out on a swept flat plate to study the process leading to the final breakdown of laminar flow. Two types of high frequency ... The experiments of primary and secondary instabilities with controlled excitation are carried out on a swept flat plate to study the process leading to the final breakdown of laminar flow. Two types of high frequency secondary instabilities are identified. The most amplified mode is centered about the inflection point of the crosswise profile of the boundary layer and is interpreted as inflectional instability, the other occurs in the one third of the boundary layer from the wall. The high frequency disturbances are highly amplified but they also saturate similarly to the primary and nonlinearly generated disturbances. Their main effect in the final breakdown seems interact with the disturbances is developed and thus widens the frequency spectrum to turbulent state. 展开更多
关键词 three dimensional boundary layer cross flow instability secondary instability final onset of transition BREAKDOWN
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ROBUST STABILIZATING FOR A OLASS OF UNOERTAIN NONLINEAR INTEROONNECTED SYSTEMS USING VARIABLE STRUCTURE CONTROL
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作者 姜斌 万健如 王先来 《Transactions of Tianjin University》 EI CAS 1999年第1期42-46,共5页
The robust stabilizating control problem for a class of uncertain nonlinear large-scale systems is discussed. Based on the theory of both input/output (I/O) linearization and decentralized variable structure control (... The robust stabilizating control problem for a class of uncertain nonlinear large-scale systems is discussed. Based on the theory of both input/output (I/O) linearization and decentralized variable structure control (VSC),two-level and decentralized variable structure control laws for this kind of systems are presented respectively,which achieve asymptotically stabilization despite the uncertainties and disturbances. At last,sirnulation of the disturbed two-pendulum system is given to illustrate the feasibility of proposed technique. 展开更多
关键词 nonlinear interconnected systems UNCERTAINTY STABILIZATION variable structure control input/output linearization
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