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Position, Singularity and Workspace Analysis of 3-PSR-O Spatial Parallel Manipulator 被引量:10
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作者 SHAO Jiejie CHEN Wenyu FU Xin 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2015年第3期437-450,共14页
Although the parallel mechanisms have the advantages of high accuracy, velocity, stiffness, and payload capacity, the shortcomings of the space utilization and workspace limit the applications in the confined space. A... Although the parallel mechanisms have the advantages of high accuracy, velocity, stiffness, and payload capacity, the shortcomings of the space utilization and workspace limit the applications in the confined space. A novel 3 degrees of freedom spatial parallel manipulator 3-PSR-O(prismatic-spherical-revolute) is proposed, which possesses a compact architecture and extended workspace while maintaining the inherent advantages of the parallel mechanisms. The direct-inverse position, singularity and workspace are investigated. The mapping method is adopted in the position analysis, and the closed form solution is derived in the form of a six order equation. The singularity analysis of the mechanism is also carried out based on the geometrical constraints, including six singularity boundaries. A feature boundary, which is independent of the prismatic joints' stroke limit, is obtained by integrating the six singularity boundaries. According to the formation of the reachable workspace, a concept of basic workspace is also introduced and presented in the analytical way. By demarcating the basic workspace along the central height with the feature boundary, the reachable workspace can be derived and analyzed more efficiently. Finally, a comparative study on the space utilization between the 3-PSP parallel mechanism and the new mechanism is also presented. The area of feature boundary of the new mechanism is about 140% of the 3-PSP parallel mechanism, while its installation radius is only 1/2 of the 3-PSP parallel mechanism. The proposed parallel mechanism shows great space utilization, and is ideally suited for applications in confined space occasions such as immersion lithography, nano-imprint etc. 展开更多
关键词 spatial-planar parallel mechanism direct-inverse position analysis reachable workspace basic workspace feature boundary
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Positive selection analysis reveals the deep-sea adaptation of a hadal sea cucumber ( Paelopatides sp.) to the Mariana Trench
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作者 Ruoyu LIU Jun LIU Haibin ZHANG 《Journal of Oceanology and Limnology》 SCIE CAS CSCD 2021年第1期266-281,共16页
The Mariana Trench,the deepest trench on the earth,is ideal for deep-sea adaptation research due to its unique characters,such as the highest hydrostatic pressure on the Earth,constant ice-cold temperature,and eternal... The Mariana Trench,the deepest trench on the earth,is ideal for deep-sea adaptation research due to its unique characters,such as the highest hydrostatic pressure on the Earth,constant ice-cold temperature,and eternal darkness.In this study,tissues of a the hadal holothurian(Paelopatides sp.)were fi xed with RNA later in situ at~6501-m depth in the Mariana Trench,which,to our knowledge,is the deepest in-situ fi xed animal sample.A high-quality transcript was obtained by de-novo transcriptome assembly.A maximum likelihood tree was constructed based on the single copy orthologs across nine species with their available omics data.To investigate deep-sea adaptation,113 positively selected genes(PSGs)were identifi ed in Paelopatides sp.Some PSGs such as microphthalmia-associated transcription factor(MITF)may contribute to the distinct phenotype of Paelopatides sp.,including its translucent white body and degenerated ossicles.At least eight PSGs(transcription factor 7-like 2[TCF7L2],ETS-related transcription factor Elf-2-like[ELF2],PERQ amino acid-rich with GYF domain-containing protein[GIGYF],cytochrome c oxidase subunit 7a,[COX7A],type I thyroxine 5′-deiodinase[DIO1],translation factor GUF1[GUF1],SWI/SNF related-matrix-associated actin-dependent regulator of chromatin subfamily C and subfamily E,member 1[SMARCC]and[SMARCE1])might be related to cold adaptation.In addition,at least nine PSGs(cell cycle checkpoint control protein[RAD9A],replication factor A3[RPA3],DNA-directed RNA polymerases I/II/III subunit RPABC1[POLR2E],putative TAR DNA-binding protein 43 isoform X2[TARDBP],ribonucleoside-diphosphate reductase subunit M1[RRM1],putative serine/threonine-protein kinase[SMG1],transcriptional regulator[ATRX],alkylated DNA repair protein alkB homolog 6[ALKBH6],and PLAC8 motif-containing protein[PLAC8])may facilitate the repair of DNA damage induced by the high hydrostatic pressure,coldness,and high concentration of cadmium in the upper Mariana Trench. 展开更多
关键词 sea cucumber Mariana Trench deep-sea adaptation positive selection analysis translucent white body ossicle degeneration
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Survey and analysis on positive rate of HCV,HBsAg,HIV and syphilis in hemophilia Ap atients during 1992~2000
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《中国输血杂志》 CAS CSCD 2001年第S1期335-,共1页
关键词 HBSAG HCV Survey and analysis on positive rate of HCV HBsAg HIV and syphilis in hemophilia Ap atients during 1992 rate HIV
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LOCATION OF DOUBLE BOND POSITION OF INSECT SEX PHEROMONE BY GC/MS ANALYSIS WITH CHEMICAL IONIZATION
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作者 Fan Lei KONG Jiangsu Institute of Ecomomes,Jintan Jiangsu,213200 《Chinese Chemical Letters》 SCIE CAS CSCD 1990年第2期109-112,共4页
Ozonolysis products of four lepidopteral pheromone were identified by methane CI-MS.The spectra obtained were notably simpler than those of EI-MS,the peak of molecular ion was normally close to the base peak,and the c... Ozonolysis products of four lepidopteral pheromone were identified by methane CI-MS.The spectra obtained were notably simpler than those of EI-MS,the peak of molecular ion was normally close to the base peak,and the characteristic fragment ions were high in m/z,thereby the interpretation was facilitated. 展开更多
关键词 MS GC LOCATION OF DOUBLE BOND POSITION OF INSECT SEX PHEROMONE BY GC/MS analysis WITH CHEMICAL IONIZATION
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An Analysis of Public Service Announcements from the Perspective of At⁃titude in Appraisal System—Take TV PSA of Environmental Protection for Examples
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作者 卢以若 《海外英语》 2021年第7期272-273,共2页
With the development of social media,the TV public service advertisements play an important role in environmental pro⁃tection.The essay will analyze PSA about environmental protection from the perspective of Attitude ... With the development of social media,the TV public service advertisements play an important role in environmental pro⁃tection.The essay will analyze PSA about environmental protection from the perspective of Attitude in Appraisal System,trying to find out how ads work by using different kinds of sub-systems in attitude.And the essay will also focus on the proportion of positive and negative meanings,researching the myth of PSA. 展开更多
关键词 Chinese public service advertisements Appraisal Theory Positive Discourse analysis
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Coupled Dynamics and Integrated Control for Position and Attitude Motions of Spacecraft:A Survey
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作者 Feng Zhang Guangren Duan 《IEEE/CAA Journal of Automatica Sinica》 SCIE EI CSCD 2023年第12期2187-2208,共22页
Inspired by the integrated guidance and control design for endo-atmospheric aircraft,the integrated position and attitude control of spacecraft has attracted increasing attention and gradually induced a wide variety o... Inspired by the integrated guidance and control design for endo-atmospheric aircraft,the integrated position and attitude control of spacecraft has attracted increasing attention and gradually induced a wide variety of study results in last over two decades,fully incorporating control requirements and actuator characteristics of space missions.This paper presents a novel and comprehensive survey to the coupled position and attitude motions of spacecraft from the perspective of dynamics and control.To this end,a systematic analysis is firstly conducted in details to show the position and attitude mutual couplings of spacecraft.Particularly,in terms of the time discrepancy between spacecraft position and attitude motions,space missions can be categorized into two types:space proximity operation and space orbital maneuver.Based on this classification,the studies on the coupled dynamic modeling and the integrated control design for position and attitude motions of spacecraft are sequentially summarized and analyzed.On the one hand,various coupled position and dynamic formulations of spacecraft based on various mathematical tools are reviewed and compared from five aspects,including mission applicability,modeling simplicity,physical clearance,information matching and expansibility.On the other hand,the development of the integrated position and attitude control of spacecraft is analyzed for two space missions,and especially,five distinctive development trends are captured for space operation missions.Finally,insightful prospects on future development of the integrated position and attitude control technology of spacecraft are proposed,pointing out current primary technical issues and possible feasible solutions. 展开更多
关键词 Coupled position and attitude dynamic modeling integrated position and attitude control position and attitude coupling analysis SPACECRAFT space missions
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Reflections on the Three Controversies in Economic Methodology by Virtue of the Philosophy of Science
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作者 Shaozhong Cui 《Economics World》 2023年第1期20-30,共11页
The philosophical foundation of the mainstream neoclassical economics is empirical philosophy.The controversies of economic methodology over inductive and deductive methods,over verificationistic and falsificationisti... The philosophical foundation of the mainstream neoclassical economics is empirical philosophy.The controversies of economic methodology over inductive and deductive methods,over verificationistic and falsificationistic approaches,and over positive and normative analyses in the evolution of economics are associated with those in the philosophy of science.The evolution of philosophy of science suggests that the above-mentioned pairs of economic methodologies should be appropriately combined when used in economics.It is not sensible to overemphasize either one inside each pair of economic methodologies. 展开更多
关键词 philosophy of science economic methodology INDUCTION DEDUCTION verification FALSIFICATION positive analysis normative analysis
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Distribution and segregation of dissolved elements in pipeline slab 被引量:3
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作者 Jianhua Liu Yanping Bao +3 位作者 Xian Dong Taiquan Li Yi Ren Shuai Zhang 《Journal of University of Science and Technology Beijing》 CSCD 2007年第3期212-218,共7页
The chemical composition in a cross section of a high grade pipeline slab was measured point by point (in a scale of 1 μm) using original position statistic distribution analysis (OPA). The result indicated that ... The chemical composition in a cross section of a high grade pipeline slab was measured point by point (in a scale of 1 μm) using original position statistic distribution analysis (OPA). The result indicated that negative segregation strips of Si, Mn, Mo, Ni, Cr, Nb, Cu, Ti, and V exist in the two sides 24 mm away from the central line, with a width of 8-12 mm, Negative segregation inside the central line is more severe than that outside the central line, and the highest positive segregation of the elements appears closely by the inner sides of the negative segregation strips. No obvious negative segregation strip of S and P is found. Segregation of the elements in the central area is higher than that in the outer and inner arc areas. The segregation of C, Ti, S, and P is high and that of Cr, Cu, Si, and Mn is low in the slab. 展开更多
关键词 original position statistic distribution analysis (OPA) SEGREGATION negative segregation PIPELINE
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Study on original position statistic quantitative method for the content of Al in inclusions from steels
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作者 LI Dongling,LI Meiling,JIA Yunhai and WANG Haizhou Central Iron & Steel Research Institute,Beijng 100081,China 《Baosteel Technical Research》 CAS 2010年第S1期120-,共1页
The inclusions of Al in steels have great influence on the properties and the quality of steels.But there are some difficulties on the content determination of Al inclusions with accuracy and rapidity.Conventional qua... The inclusions of Al in steels have great influence on the properties and the quality of steels.But there are some difficulties on the content determination of Al inclusions with accuracy and rapidity.Conventional quantity analysis of stable inclusions is electrolysis method with the disadvantages of long analytical period,trivial operation and a little loss of some fine and instable oxides.The content of insoluble aluminum can be obtained by the subtraction between the content of total Al and acid soluble Al determined by chemical methods with the disadvantage of complicate procedure.Original position statistic distribution analysis(OPA) can be used for the determination of inclusions by collecting and discriminating the signals produced by single spark discharge in the way of no pre-sparking,scanning and emitting continuously.In this study the element of Al in some spectrum certified reference materials of carbon and medium or low-alloyed steels was analyzed by original opposition statistic distribution technique.Two quantitative mathematical models used by original position distribution analysis technology for the analysis of the content of Al inclusions have been investigated and been applied to the analysis of the content of Al inclusions in many kinds of spectrum certified reference materials and some medium and low-alloyed steel samples.The scope of application of the models and their limited conditions were discussed.It was found that the results calculated by OPA had great difference with the value by chemical method for some samples with the total content of Al above 0.2%.The reason is that some intensity of abnormal sparks have gone beyond the range of the largest intensity that can be determined by the instrument so that there is a certain deviation on the identification of abnormal sparks and the calculation of threshold value.It was found that the size distribution of Al inclusions had a great influence on the application of the two models.For most of certified reference materials for spectrum analysis and real steel samples the results of the content of Al in inclusions calculated by model 1 was satisfied and had good coincidence with the value of insoluble Al by chemical method. But for the samples with so many large inclusions of Al existed,the influence of intensity should be considered because the signal increase did not vary in the form of simple function.So model 2 was more suitable for the content calculation of Al in inclusions in this case.In order to choose suitable model to be used it is suggested that the size distribution of inclusions should be determined by OPA before content determination of Al in inclusions. The results of the content of Al inclusions calculated by the selected mathematical model were satisfied and had good coincidence with the value of insoluble Al obtained by the subtraction between the content of total Al and soluble Al determined by chemical methods when the content of total aluminum was below 0.2%. 展开更多
关键词 STEEL aluminum inclusions original position statistic distribution analysis mathematical quantitative model insoluble aluminum
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Propagation Mechanisms of Incident Tsunami Wave in Jiangsu Coastal Area,Caused by Eastern Japan Earthquake on March 11,2011
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作者 袁春光 王义刚 +2 位作者 黄惠明 陈橙 陈大可 《China Ocean Engineering》 SCIE EI CSCD 2016年第1期123-136,共14页
At 13:46 on March 11, 2011(Beijing time), an earthquake of Mw=9.0 occurred in Japan. By comparing the tsunami data from Guanhekou marine station with other tsunami wave observation gathered from southeast coastal a... At 13:46 on March 11, 2011(Beijing time), an earthquake of Mw=9.0 occurred in Japan. By comparing the tsunami data from Guanhekou marine station with other tsunami wave observation gathered from southeast coastal area of China, it was evident that, only in Guanhekou, the position of the maximum wave height appeared in the middle part rather than in the front of the tsunami wave train. A numerical model of tsunami propagation based on 2-D nonlinear shallow water equations was built to study the impact range and main causes of the special tsunami waveform discovered in Jiangsu coastal area. The results showed that nearly three-quarters of the Jiangsu coastal area, mainly comprised the part north of the radial sand ridges, reached its maximum tsunami wave height in the middle part of the wave train. The main cause of the special waveform was the special underwater topography condition of the Yellow Sea and the East China Sea area, which influenced the tsunami propagation and waveform significantly. Although land boundary reflection brought an effect on the position of the maximum wave height to a certain extent, as the limits of the incident waveform and distances between the observation points and shore, it was not the dominant influence factor of the special waveform. Coriolis force's impact on the tsunami waves was so weak that it was not the main cause for the special phenomenon in Jiangsu coastal area. The study reminds us that the most destructive wave might not appear in the first one in tsunami wave train. 展开更多
关键词 Jiangsu coastal area tsunami wave the maximum wave height occurrence position wave train causes analysis
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Polynomial regression calculation of the Earth's position based on millisecond pulsar timing
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作者 Feng Tian 1,2,Zheng-Hong Tang 1,Qing-Zeng Yan 1,2 and Yong Yu 11 Shanghai Astronomical Observatory,Chinese Academy of Sciences,Shanghai 200030,China 2 Graduate University of Chinese Academy of Sciences,Beijing 100049,China 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2012年第2期219-234,共16页
Prior to achieving high precision navigation of a spacecraft using X-ray observations, a pulsar rotation model must be built and analysis of the precise posi- tion of the Earth should be performed using ground pulsar ... Prior to achieving high precision navigation of a spacecraft using X-ray observations, a pulsar rotation model must be built and analysis of the precise posi- tion of the Earth should be performed using ground pulsar timing observations. We can simulate time-of-arrival ground observation data close to actual observed values before using pulsar timing observation data. Considering the correlation between the Earth's position and its short arc section of an orbit, we use polynomial regression to build the correlation. Regression coefficients can be calculated using the least square method, and a coordinate component series can also be obtained; that is, we can calcu- late Earth's position in the Barycentric Celestial Reference System according to pulse arrival time data and a precise pulsar rotation model. In order to set appropriate param- eters before the actual timing observations for Earth positioning, we can calculate the influence of the spatial distribution of pulsars on errors in the positioning result and the influence of error source variation on positioning by simulation. It is significant that the threshold values of the observation and systematic errors can be established before an actual observation occurs; namely, we can determine the observation mode with small errors and reject the observed data with big errors, thus improving the positioning result. 展开更多
关键词 autonomous positioning - millisecond pulsar - pulsar timing - re-gression analysis
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An Implementation Technique for Multivariate Robust Design
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作者 MAYi-zhong ZHAOFeng-yu 《International Journal of Plant Engineering and Management》 2005年第1期47-53,共7页
This paper investigates systematically the problem of multivariate robustparameter design. First, a measurement criterion for the total variation of multivariate qualitycharacteristics is introduced by the result of i... This paper investigates systematically the problem of multivariate robustparameter design. First, a measurement criterion for the total variation of multivariate qualitycharacteristics is introduced by the result of information theory. Then the implementation procedurein the robust design is presented. After that, a simulation example from a practical industrialprocess is provided. Finally, some comments and further work are discussed. 展开更多
关键词 multivariate robust design implementation procedure positive analysis
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Recovering from cultural blindness:multimodal Positive Discourse Analysis of metaphors in hand-drawn sketches about Islam
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作者 May S.El-Falaky 《Language and Semiotic Studies》 2023年第3期333-358,共26页
This paper extends Nartey's model of Positive Discourse Analysis(PDA),examining the visual metaphors(VM)in the representations of Islamic identity.The paper highlights how hand-drawings operate as a positive disco... This paper extends Nartey's model of Positive Discourse Analysis(PDA),examining the visual metaphors(VM)in the representations of Islamic identity.The paper highlights how hand-drawings operate as a positive discourse resisting negative accusations in hegemonic discourses about Islam.This PDA study is an intellectual proximity between semiotics,VMs and cultural studies.Through the constructed framework,I argue that PDA can utilize VMs to construct/construe homogeneity and inclusiveness.Through the findings of this study,we can construe the imageries as a reflection of the physical and cultural environments whose cognition is attained by examining how semiotic signs reflect and are reflected by conscious awareness and perception.A major criticism of PDA is its lack of contextual framing,that's why this paper provides a contextual framing mixing semiotic visuality and the sociocultural construal of discursive representation of Muslim identity.The interpretation of the findings is contextualized after the adaptation of the philosophical view of Molymeux's question,the issue of blindnessfrom birth,and the capability of seeing things properly if someone,hypothetically,gains his sight again. 展开更多
关键词 culture ISLAM Molyneux's problem MULTIMODALITY Positive Discourse analysis social semiotics visual metaphors
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A New Solution to the Inverse Position Analysis of the Redundant Serial Robot 被引量:2
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作者 赵永杰 董兴建 《Journal of Shanghai Jiaotong university(Science)》 EI 2010年第5期610-614,共5页
A new solution to the inverse position analysis of the redundant serial robot is presented.The inverse position analysis problem of the redundant serial robot is transformed into a minimization problem and then the op... A new solution to the inverse position analysis of the redundant serial robot is presented.The inverse position analysis problem of the redundant serial robot is transformed into a minimization problem and then the optimization method is adopted to solve the nonlinear least square problem with the analytic form of a new Jacobi matrix.In this way,the inverse solution of the redundant serial robot can be searched out quickly under the desired precision when the positions of the three non-collinear end effector points are given.The inverse position analysis of the 7R redundant serial robot is illustrated as an example and the simulation results verify the efficiency of the proposed algorithm. 展开更多
关键词 inverse position analysis redundant serial robot optimization method
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Genome-Wide Linkage and Positional Association Analyses Identify Associations of Novel AFF3 and NTM Genes with Triglycerides:The GenSalt Study 被引量:1
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作者 Changwei Li Lydia A.L.Bazzano +14 位作者 Dabeeru C.Rao James E.Hixson Jiang He Dongfeng Gu Charles C.Gu Lawrence C.Shimmin Cashell E.Jaquish Karen Schwander De-Pei Liu Jianfeng Huang Fanghong Lu Jie Cao Shen Chong Xiangfeng Lu Tanika N.Kelly 《Journal of Genetics and Genomics》 SCIE CAS CSCD 2015年第3期107-117,共11页
We conducted a genome-wide linkage scan and positional association study to identify genes and variants influencing blood lipid levels among participants of the Genetic Epidemiology Network of Salt-Sensitivity (GenS... We conducted a genome-wide linkage scan and positional association study to identify genes and variants influencing blood lipid levels among participants of the Genetic Epidemiology Network of Salt-Sensitivity (GenSalt) study. The GenSalt study was conducted among 1906 participants from 633 Han Chinese families. Lipids were measured from overnight fasting blood samples using standard methods. Multipoint quantitative trait genome-wide linkage scans were performed on the high-density lipoprotein, low-density lipoprotein, and log- transformed triglyceride phenotypes. Using dense panels of single nucleotide polymorphisms (SNPs), single-marker and gene-based association analyses were conducted to follow-up on promising linkage signals. Additive associations between each SNP and lipid phenotypes were tested using mixed linear regression models. Gene-based analyses were performed by combining P-values from single- marker analyses within each gene using the truncated product method (TPM). Significant associations were assessed for replication among 777 Asian participants of the Multi-ethnic Study of Atherosclerosis (MESA). Bonferroni correction was used to adjust for multiple testing. In the GenSalt study, suggestive linkage signals were identified at 2p11.2-2q12.1 [maximum multipoint LOD score (MML) = 2.18 at 2q11.2] and t lq24.3-11q25 (MML = 2.29 at 11q25) for the log-transformed triglyceride phenotype. Follow-up analyses of these two regions revealed gene-based associations of charged multivesicular body protein 3 (CHMP3), ring finger protein 103 (RNF103), AF4/FMR2 family, member 3 (AFF3), and neurotrirnin (NTM) with triglycerides (P = 4 ×10^-4, 1.00 × 10^-5, 2.00 × 10^-5, and 1.00 × 10^-7, respectively). Both the AFF3 and NTM triglyceride associations were replicated among MESA study participants(P = 1.00 × 10^-7 and 8.00× 10^-5, respectively). Furthermore, NTM explained the linkage signal on chromosome 11, In conclusion, we identified novel genes associated with lipid phenotypes in linkage regions on chromosomes 2 and 11. 展开更多
关键词 LIPIDS Linkage analysis positional association analysis Gene-based analysis
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Multimodal positive discourse analysis of national image publicity video
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作者 Chenghui Guan 《Language and Semiotic Studies》 2022年第3期66-85,共20页
This study employs a revised theoretical framework of multimodal positive discourse analysis to analyze the process of national image construction in a Chinese video.In contrast to original studies focusing mainly on ... This study employs a revised theoretical framework of multimodal positive discourse analysis to analyze the process of national image construction in a Chinese video.In contrast to original studies focusing mainly on language or text and image,this study considers three interrelated multimodal resources:sound,image,and language.Different modalities play different roles in national image construction,and they also collaborate with each other for a uniform purpose.Specific multimodal working mechanisms contribute to the construction of a positive national image.Multimodal resources are also signs in the sense of semiotics,which are perceived by different sense organs and take effect in producing vivid and impressive senses. 展开更多
关键词 image LANGUAGE MULTIMODALITY positive discourse analysis SEMIOTICS SOUND
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ACTUAL ANALYSIS AND THEORETICAL SIMULATION ON POSITION OF SUBTROPICAL HIGHS OVER WESTERN PACIFIC
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作者 董步文 丑纪范 《Acta meteorologica Sinica》 SCIE 1989年第5期618-622,共5页
In this paper,using a nonlinear low-order barotropic system with orography and momentum forcing as well as dissipation,we have theoretically calculated the two kinds of curves for the seasonal northward movement of su... In this paper,using a nonlinear low-order barotropic system with orography and momentum forcing as well as dissipation,we have theoretically calculated the two kinds of curves for the seasonal northward movement of subtropical highs.It has been shown that the theoretical results resemble basically with the analysed results of wave spectrum data. 展开更多
关键词 ACTUAL analysis AND THEORETICAL SIMULATION ON POSITION OF SUBTROPICAL HIGHS OVER WESTERN PACIFIC LINE
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Apparel Industry Witnesses Positive Activity Analysis of economic performance of China's apparel industry in Jan.-Aug.
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作者 Guoyun 《纺织服装周刊》 2010年第44期9-9,共1页
Production Recovery China’s apparel industry saw a sharp increase in the output for the January-September period, according to data collected from statistics-worthy
关键词 ACTIVITY Apparel Industry Witnesses Positive Activity analysis of economic performance of China’s apparel industry in Jan Aug
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Analysis of the linkage positions and isomers of monosaccharide units in oligosaccharides by negative secondary ion mass spectrometry in combination with the stereoselective reaction with substituted boronic acid
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作者 YAN,Lin FANG,Yi-Wei Institute of Chemistry,Chinese Academy of Sciences,Beijing 100080 《Chinese Journal of Chemistry》 SCIE CAS CSCD 1993年第1期53-58,共8页
The negative secondary ion mass spectrometry,in combination with the stereoselective derivatizations with substituted boronic acid RB(OH)_2,was used in the analysis of fourteen oligosac- charides.The mass spectra of t... The negative secondary ion mass spectrometry,in combination with the stereoselective derivatizations with substituted boronic acid RB(OH)_2,was used in the analysis of fourteen oligosac- charides.The mass spectra of the derivatives provide information on their linkage Positions and iso- merism of the individual monoscaccharide units.The results indicated that among the derivatives of the oligosaccharides analyzed,those with 1—4 and 1—6 linkages all presented the ion peaks at m/z 287,sometimes one more peak at m/z 449.Furthermore,a relationship was found between the linkage positions and the intensity orders of the derivative ions.Finally,the derivatives of the disaccharides with a galactose presented an intense ion peak at m/z 347,and those of oligosaccharides with 1—6 linkage to a galactose at terminal presented the ion at m/z 317.In the case of oligosaccharides with a fructose residue,characteristic ion of m/z 155 was produced.The conditions of stereoselective derivatizations and mass spectrometry were studied,in order to obtain a better reproducibility of the mass spectra. 展开更多
关键词 analysis of the linkage positions and isomers of monosaccharide units in oligosaccharides by negative secondary ion mass spectrometry in combination with the stereoselective reaction with substituted boronic acid acid
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Research on uncertainty in measurement assisted alignment in aircraft assembly 被引量:17
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作者 Chen Zhehan Du Fuzhou Tang Xiaoqing 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 2013年第6期1568-1576,共9页
Operations in assembling and joining large size aircraft components are changed to novel digital and flexible ways by digital measurement assisted alignment.Positions and orientations(P&O)of aligned components are ... Operations in assembling and joining large size aircraft components are changed to novel digital and flexible ways by digital measurement assisted alignment.Positions and orientations(P&O)of aligned components are critical characters which assure geometrical positions and relationships of those components.Therefore,evaluating the P&O of a component is considered necessary and critical for ensuring accuracy in aircraft assembly.Uncertainty of position and orientation(U-P&O),as a part of the evaluating result of P&O,needs to be given for ensuring the integrity and credibility of the result;furthermore,U-P&O is necessary for error tracing and quality evaluating of measurement assisted aircraft assembly.However,current research mainly focuses on the process integration of measurement with assembly,and usually ignores the uncertainty of measured result and its influence on quality evaluation.This paper focuses on the expression,analysis,and application of U-P&O in measurement assisted alignment.The geometrical and algebraical connotations of U-P&O are presented.Then,an analytical algorithm for evaluating the multi-dimensional U-P&O is given,and the effect factors and characteristics of U-P&O are discussed.Finally,U-P&O is used to evaluate alignment in aircraft assembly for quality evaluating and improving.Cases are introduced with the methodology. 展开更多
关键词 Aircraft manufacturing Large size components alignment Measurement assisted assembly Quality assurance Uncertainty analysis Uncertainty of position and orientation
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