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On the representations of string pairs over virtual field
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作者 TAO Kun FU Chang-Jian 《四川大学学报(自然科学版)》 北大核心 2025年第5期1103-1108,共6页
Let F_(1)be the virtual field consisting of one element and(Q,I)a string pair.In this paper,we study the representations of string pairs over the virtual field F_(1).It is proved that an indecomposable F_(1)-represent... Let F_(1)be the virtual field consisting of one element and(Q,I)a string pair.In this paper,we study the representations of string pairs over the virtual field F_(1).It is proved that an indecomposable F_(1)-representation is either a string representation or a band representation by using the coefficient quivers.It is worth noting that for a given band and a positive integer,there exists a unique band representation up to isomorphism. 展开更多
关键词 string pair string representation band representation
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Axionic excitation and vorticity in a QCD string model with anomaly inflow
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作者 Chi Xiong 《Communications in Theoretical Physics》 2025年第7期63-69,共7页
A new phenomenological model(axionic QCD string)is constructed to study the topological issues of the QCD vacuum and hadron structure.It provides an alternative way of tackling the Strong CP problem,which is different... A new phenomenological model(axionic QCD string)is constructed to study the topological issues of the QCD vacuum and hadron structure.It provides an alternative way of tackling the Strong CP problem,which is different from the traditional Peccei–Quinn approach.Neither new particle nor extra symmetry is introduced,and the role of the Peccei–Quinn axion is played by a quasiparticle arising from the phase of the quark condensate,dubbed as axionic excitation.The derivative of this excitation field is decomposed into a regular part and a singular part,and the latter contains vorticity from the string configuration.A hidden gauge symmetry is revealed in this decomposition and vorticity is represented by an emergent gauge field associated with anomalies.These components,together with the anomaly-inflow mechanism,complete the effective Lagrangian description for the axionic QCD string. 展开更多
关键词 QCD vacuum axion string axial anomaly quark condensate quantized vorticity
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Quasinormal modes and shadow of Schwarzschild black holes embedded in a Dehnen-type dark matter halo exhibiting a cloud of strings
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作者 Ahmad Al-Badawi Sanjar Shaymatov 《Communications in Theoretical Physics》 2025年第3期101-111,共11页
In this paper we consider a static spherically symmetric black hole(BH)embedded in a Dehnen-(1,4,0)-type dark matter(DM)halo in the presence of a cloud string.We examine and present data on how the core density of the... In this paper we consider a static spherically symmetric black hole(BH)embedded in a Dehnen-(1,4,0)-type dark matter(DM)halo in the presence of a cloud string.We examine and present data on how the core density of the DM halo parameter and the cloud string parameter affect BH attributes such as quasinormal modes(QNMs)and shadow cast.To do this,we first look into the effective potential of perturbation equations for three types of perturbation fields with different spins:massless scalar field,electromagnetic field and gravitational field.Then,using the sixth-order Wentzel-Kramers-Brillouin approximation,we examine QNMs of the BH disturbed by the three fields and derive quasinormal frequencies.The changes in QNM versus the core density parameter and the cloud string parameter for three disturbances are explored.We also investigate how the core density and the cloud string parameter affect the photon sphere and shadow radius.Interestingly,the study shows that the influence of Dehnen-type DM and cloud strings increases both the photon sphere and the shadow radius.Finally,we employ observational data from Sgr A^(*) and M87^(*) to set limitations on the BH parameters. 展开更多
关键词 SCHWARZSCHILD Dehnen type dark matter halo string cloud quasinormal modes SHADOW
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On the Lebesgue Integral and the Lebesgue Measure: Mathematical Applications in Some Sectors of Chern-Simons Theory and Yang-Mills Gauge Theory and Mathematical Connections with Some Sectors of String Theory and Number Theory
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作者 Michele Nardelli 《Journal of Modern Physics》 2025年第1期93-132,共40页
In this paper, in Section 1, we have described some equations and theorems concerning the Lebesgue integral and the Lebesgue measure. In Section 2, we have described the possible mathematical applications, of Lebesgue... In this paper, in Section 1, we have described some equations and theorems concerning the Lebesgue integral and the Lebesgue measure. In Section 2, we have described the possible mathematical applications, of Lebesgue integration, in some equations concerning various sectors of Chern-Simons theory and Yang-Mills gauge theory, precisely the two dimensional quantum Yang-Mills theory. In conclusion, in Section 3, we have described also the possible mathematical connections with some sectors of String Theory and Number Theory, principally with some equations concerning the Ramanujan’s modular equations that are related to the physical vibrations of the bosonic strings and of the superstrings, some Ramanujan’s identities concerning π and the zeta strings. 展开更多
关键词 Lebesgue Integral Chern-Simons Theory Yang-Mills Gauge Theory string Theory Number Theory
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Numerical investigation of wellbore damage due to drill string lateral vibration
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作者 Hadi Haghgouei Anders Nermoen Alexandre Lavrov 《Journal of Rock Mechanics and Geotechnical Engineering》 2025年第3期1287-1301,共15页
During drilling operations,cyclic loading is exerted on the wellbore wall by the vibrations of the drill string.This loading could lead to rock fatigue,which in turn might result in wellbore failure.In this study,a nu... During drilling operations,cyclic loading is exerted on the wellbore wall by the vibrations of the drill string.This loading could lead to rock fatigue,which in turn might result in wellbore failure.In this study,a numerical model is developed to simulate the effects of repeated loading on rock fatigue and failure.The simulation is based on an elasto-plastic constitutive model coupled with a damage mechanics approach,which allows us to examine the wellbore instability due to drill string vibrations.The model is verified with the existing data in the literature related to experiments on impact of a steel ball against a curved wall.The findings indicate that cyclic loading increases the development of plastic strain around the wellbore significantly compared to static conditions,promoting rock fatigue.Furthermore,the cyclic loading expands the radius of the yielded zone substantially,a critical factor for maintaining wellbore integrity.The proposed model can be used to evaluate the wellbore stability under repetitive loading caused by the drill string action. 展开更多
关键词 Wellbore stability Damage mechanics Fatigue modeling Drill string vibration
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Branes in String/M-Theory
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作者 J X Lu 《Communications in Theoretical Physics》 2025年第9期170-194,共25页
This is a writeup of lectures delivered at the Asian Pacific Introductory School on Superstring and Related Topics in Beijing(2006)and an expanded version of these lectures given at the Third Summer School on Strings,... This is a writeup of lectures delivered at the Asian Pacific Introductory School on Superstring and Related Topics in Beijing(2006)and an expanded version of these lectures given at the Third Summer School on Strings,Fields and Holography in Nanjing(2023).It aims to provide both a historical and pedagogical account of developments in finding 1/2 Bogomol?nyi–Prasad–Sommerfield(BPS)extended string solitons during the early stage of the so-called second string revolution,before which these objects were thought to be unrelated to strings.Nonsupersymmetric solutions related to brane/anti brane systems or non-BPS systems are also discussed. 展开更多
关键词 p-brane D-BRANE string/M-Theory
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The analysis of drill string dynamics for extra-deep wells based on successive over-relaxation node iteration method
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作者 Wen-Chang Wang He-Yuan Yang +4 位作者 Da-Kun Luo Ming-Ming You Xing Zhou Feng Chen Qin-Feng Di 《Petroleum Science》 2025年第8期3293-3303,共11页
The complex vibration directly affects the dynamic safety of drill string in ultra-deep wells and extra-deep wells.It is important to understand the dynamic characteristics of drill string to ensure the safety of dril... The complex vibration directly affects the dynamic safety of drill string in ultra-deep wells and extra-deep wells.It is important to understand the dynamic characteristics of drill string to ensure the safety of drill string.Due to the super slenderness ratio of drill string,strong nonlinearity implied in dynamic analysis and the complex load environment,dynamic simulation of drill string faces great challenges.At present,many simulation methods have been developed to analyze drill string dynamics,and node iteration method is one of them.The node iteration method has a unique advantage in dealing with the contact characteristics between drill string and borehole wall,but its drawback is that the calculation consumes a considerable amount of time.This paper presents a dynamic simulation method of drilling string in extra-deep well based on successive over-relaxation node iterative method(SOR node iteration method).Through theoretical analysis and numerical examples,the correctness and validity of this method were verified,and the dynamics characteristics of drill string in extra-deep wells were calculated and analyzed.The results demonstrate that,in contrast to the conventional node iteration method,the SOR node iteration method can increase the computational efficiency by 48.2%while achieving comparable results.And the whirl trajectory of the extra-deep well drill string is extremely complicated,the maximum rotational speed downhole is approximately twice the rotational speed on the ground.The dynamic torque increases rapidly at the position of the bottom stabilizer,and the lateral vibration in the middle and lower parts of drill string is relatively intense. 展开更多
关键词 Extra-deep well Drill string dynamics Calculation speed-up method SOR iteration method
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Detachable string magnetically controlled capsule endoscopy for the noninvasive diagnosis of esophageal diseases:A prospective,blind clinical study 被引量:2
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作者 Yan-Ling Yang Huang-Wen Qin +5 位作者 Zhao-Yu Chen Hui-Ning Fan Yi Yu Wei Da Jin-Shui Zhu Jing Zhang 《World Journal of Gastroenterology》 SCIE CAS 2024年第9期1121-1131,共11页
BACKGROUND Traditional esophagogastroduodenoscopy(EGD),an invasive examination method,can cause discomfort and pain in patients.In contrast,magnetically controlled capsule endoscopy(MCE),a noninvasive method,is being ... BACKGROUND Traditional esophagogastroduodenoscopy(EGD),an invasive examination method,can cause discomfort and pain in patients.In contrast,magnetically controlled capsule endoscopy(MCE),a noninvasive method,is being applied for the detection of stomach and small intestinal diseases,but its application in treating esophageal diseases is not widespread.AIM To evaluate the safety and efficacy of detachable string MCE(ds-MCE)for the diagnosis of esophageal diseases.METHODS Fifty patients who had been diagnosed with esophageal diseases were pros-pectively recruited for this clinical study and underwent ds-MCE and conven-tional EGD.The primary endpoints included the sensitivity,specificity,positive predictive value,negative predictive value,and diagnostic accuracy of ds-MCE for patients with esophageal diseases.The secondary endpoints consisted of visualizing the esophageal and dentate lines,as well as the subjects'tolerance of the procedure.RESULTS Using EGD as the gold standard,the sensitivity,specificity,positive predictive value,negative predictive value,and diagnostic accuracy of ds-MCE for esophageal disease detection were 85.71%,86.21%,81.82%,89.29%,and 86%,respectively.ds-MCE was more comfortable and convenient than EGD was,with 80%of patients feeling that ds-MCE examination was very comfortable or comfortable and 50%of patients believing that detachable string v examination was very convenient.CONCLUSION This study revealed that ds-MCE has the same diagnostic effects as traditional EGD for esophageal diseases and is more comfortable and convenient than EGD,providing a novel noninvasive method for treating esophageal diseases. 展开更多
关键词 Clinical trial Detachable string magnetically controlled capsule endoscopy ESOPHAGOGASTRODUODENOSCOPY Noninvasive diagnosis Esophageal diseases
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STRING STABILITY OF INFINITE INTERCONNECTED SYSTEMS
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作者 张继业 杨翊仁 曾京 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI 2000年第7期791-796,共6页
The notion of string stability of a countably infinite interconnection of a class of nonlinear system was introduced. Intuitively, string stability implies uniform boundedness of all the stares of the interconnected s... The notion of string stability of a countably infinite interconnection of a class of nonlinear system was introduced. Intuitively, string stability implies uniform boundedness of all the stares of the interconnected system for all time if the initial states of the interconnected system are uniformly bounded. Vector V-function method used to judge the stability is generalized for infinite interconnected system and sufficient conditions which guarantee the asymptotic string stability of a class of interconnected system are given. The stability regions obtained here are much larger than those in previous papers. The method given here overcomes some difficulties to deal with stability of infinite nonlinear interconnected system in previous papers. 展开更多
关键词 INFINITE-DIMENSION interconnected system vector V-function method string stability
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Calculation of the Gas Injection Rate and Pipe String Erosion in Nitrogen Drilling Systems
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作者 Mingren Shao Chunpeng Wang +3 位作者 Degui Wang Wenbo Mei Mingjie Li Hao Yang 《Fluid Dynamics & Materials Processing》 EI 2022年第2期417-430,共14页
Detailed information is provided for the design and construction of nitrogen drilling in a coal seam.Two prototype wells are considered.The Guo model is used to calculate the required minimum gas injection rate,while ... Detailed information is provided for the design and construction of nitrogen drilling in a coal seam.Two prototype wells are considered.The Guo model is used to calculate the required minimum gas injection rate,while the Finnie,Sommerfeld,and Tulsa models are exploited to estimate the ensuing erosion occurring in pipe strings.The calculated minimum gas injection rates are 67.4 m^(3)/min(with water)and 49.4 m^(3)/min(without water),and the actual field of use is 90–120 m^(3)/min.The difference between the calculated injection pressure and the field value is 6.5%–15.2%(formation with water)and 0.65%–7.32%(formation without water).The results show that the Guo model can more precisely represent the situation of the no water formation in the nitrogen drilling of a coal seam.The Finnie,Sommerfeld,and Tulsa models have different sensitivities to cutting densities,particle size,impact velocity and angle,and pipe string hardness. 展开更多
关键词 Coalbed methane nitrogen drilling minimum gas injection rate erosion of pipe string analysis on the scene
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Subscription to Digital Libraries and Corresponding Journal Impact: A Value-Based Approach to Demand for Digital Research Data—Confucian Integration of Curricula and “Market String” Digital Education Systems
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作者 Soumitra K.Mallick 《Journal of Applied Mathematics and Physics》 2018年第10期1988-1996,共9页
This paper develops a functional relation between Digital Libraries and Confucion Integrated Curriculum Learning systems. We show that under certain properties of Learning Systems which can implement laissez-faire mar... This paper develops a functional relation between Digital Libraries and Confucion Integrated Curriculum Learning systems. We show that under certain properties of Learning Systems which can implement laissez-faire markets under uncertainty, the systems integration is possible in entropy space. 展开更多
关键词 CONFUCIAN Dao and Li string Classification and INTEGRATION of Curricula DIGITAL Libraries
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Investigating the expression profiles of cysteine string proteins(CSPs)in cochlear tissue
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作者 Shili Zhang Caiji Wang +1 位作者 Yuehua Qiao Xi Shi 《Journal of Otology》 CAS CSCD 2024年第4期193-199,共7页
Objective:This study aims to explore the expression patterns of cysteine string protein alpha(CSPα)and cysteine string protein beta(CSPβ)in the mammalian inner ear,with an emphasis on their temporal dynamics during ... Objective:This study aims to explore the expression patterns of cysteine string protein alpha(CSPα)and cysteine string protein beta(CSPβ)in the mammalian inner ear,with an emphasis on their temporal dynamics during the developmental stages of C57BL/6 mice.Methods:We utilized immunofluorescence staining to assess the localization and distribution of CSPαand CSPβwithin the inner ears of C57BL/6 mice and miniature pigs.Additionally,this method facilitated the investigation of their temporal expression profiles.Results:In adult C57BL/6 mice and miniature pigs,CSPαand CSPβwere identified in the cytoplasm of inner hair cells and spiral ganglion cells,yet were absent in outer hair cells.Both proteins were found to colocalize with Ctbp2 on the basal side of the cytoplasm in inner hair cells’basilar membrane.Expression of CSPαwas observed at the nerve fiber termini at the basilar membrane’s base of inner and outer hair cells 10 days postnatally in C57BL/6 mice.Notably,expression of both CSPαand CSPβin the cytoplasm of inner hair cells emerged on the 12th day post-birth,aligning with the timeline for registering cochlear potentials.The expression levels of both proteins increased with age,but were consistently absent in outer hair cells.Contrastingly,expression of CSPαand CSPβwas present in the cytoplasm of inner hair cells in miniature pigs as early as one day post-birth,yet remained absent in the three rows of outer hair cells.Conclusion:CSPαand CSPβexhibit predominant and specific expression in inner hair cells and spiral ganglion cells.A unique expression pattern was observed for CSPα,which was also present at the nerve fiber endings of both inner and outer hair cells.The developmental expression trajectory of CSPαand CSPβin mouse inner hair cells is characterized by an initial absence,followed by a gradual increase.Moreover,the timing of expression onset between mice and miniature pigs indicates distinct temporal dynamics,suggesting a potential role in auditory development. 展开更多
关键词 Cysteine string protein CSPα CSPβ Miniature pig C57BL/6 mouse
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Elementary Fermions: Strings, Planck Constant, Preons and Hypergluons
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作者 Doron Kwiat 《Journal of High Energy Physics, Gravitation and Cosmology》 CAS 2024年第1期82-100,共19页
Using real fields instead of complex ones, it is suggested here that the fermions are pairs of coupled strings with an internal tension. The interaction between the two coupled strings is due to an exchange mechanism ... Using real fields instead of complex ones, it is suggested here that the fermions are pairs of coupled strings with an internal tension. The interaction between the two coupled strings is due to an exchange mechanism which is proportional to Planck’s constant. This may be the result of two massless bosons (hypergluons) coupled by a preon (prequark) exchange. It also gives a physical explanation to the origin of the Planck constant, and origin of spin. 展开更多
关键词 FERMIONS Preons Hypergluons strings Real Fields Planck Constant INTERFERENCE SPIN
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Towards 6D Little String Theory of Particles
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作者 Risto Raitio 《Journal of High Energy Physics, Gravitation and Cosmology》 CAS 2024年第2期546-561,共16页
A model for particles based on preons in chiral, vector and tensor/graviton supermultiplets of unbroken global supersymmetry is engineered. The framework of the model is little string theory. Phenomenological predicti... A model for particles based on preons in chiral, vector and tensor/graviton supermultiplets of unbroken global supersymmetry is engineered. The framework of the model is little string theory. Phenomenological predictions are discussed. 展开更多
关键词 Standard Model Composite Models SUPERSYMMETRY Little string Theory T-DUALITY HOLOGRAPHY
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Stringy Phenomenology with Preon Models
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作者 Risto Raitio 《Journal of High Energy Physics, Gravitation and Cosmology》 CAS 2024年第1期1-7,共7页
We compare, following Pati, global symmetries, our topological supersymmetric preon model with the heterotic E<sub>8</sub> × E<sub>8</sub> string theory. We include Pati’s supergravity ba... We compare, following Pati, global symmetries, our topological supersymmetric preon model with the heterotic E<sub>8</sub> × E<sub>8</sub> string theory. We include Pati’s supergravity based preon model in this work and compare the preon interactions of his model to ours. Based on preon-string symmetry comparison and preon phenomenological results, we conclude that the fundamental particles are likely preons rather than standard model particles. . 展开更多
关键词 Topological Field Theory Chern-Simons Theory SUPERSYMMETRY string Theory
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Edward Witten: The father of modern string theory
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作者 孙启禄 《疯狂英语(新读写)》 2024年第12期27-30,75,76,共6页
Edward Witten has been described as“the most brilliant physicist of his generation”,and some even compare him to Isaac Newton.A deeply original and dedicated theoretical physicist,Witten's primary focus is strin... Edward Witten has been described as“the most brilliant physicist of his generation”,and some even compare him to Isaac Newton.A deeply original and dedicated theoretical physicist,Witten's primary focus is string theory—a“theory of everything”that proposes the universe's fundamental components are curves,or“strings”arranged in loops.in loops.He has been a leading advocate and influential contributor in this field,famously stating,“It was very clear that if I didn't spend my life concentrating on string theory,I would simply be missing my life's calling.” 展开更多
关键词 THEORY simply string
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多自由度体系的动力放大系数解析研究
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作者 张超 周桢干 +2 位作者 赖志超 付馨迪 杨晓强 《振动工程学报》 北大核心 2025年第3期550-557,共8页
在结构动力冲击响应分析中,通常采用动力放大系数(DAF)简化计算结构的动力响应。但是,目前工程结构中对DAF的取值还存在争议。针对此问题,本文推导了多自由度(MDOF)体系的DAF解析表达式,分析了DAF大于2.0的前提条件;分别通过单自由度(SD... 在结构动力冲击响应分析中,通常采用动力放大系数(DAF)简化计算结构的动力响应。但是,目前工程结构中对DAF的取值还存在争议。针对此问题,本文推导了多自由度(MDOF)体系的DAF解析表达式,分析了DAF大于2.0的前提条件;分别通过单自由度(SDOF)体系和MDOF体系算例模型验证了解析表达式的准确性,解释了MDOF体系的DAF大于2.0的原因。基于所提出的DAF解析表达式分析了张弦梁剩余结构在断索冲击作用下的DAF分布规律。分析结果表明:当某一阶模态振型的分量与静力响应值反向时,张弦梁的DAF可能会大于2.0;即使在有阻尼情况下,张弦梁的DAF也可能会大于2.0。 展开更多
关键词 多自由度体系 张弦梁 动力放大系数 断索冲击
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弦理论与刚性索理论频率误差曲线在工程中的应用 被引量:1
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作者 蔡汶秀 郑罡 +1 位作者 孙测世 唐宇 《振动与冲击》 北大核心 2025年第9期147-152,共6页
弦理论方法有效识别索力对拉索的评估具有重要意义。为解决拉索的弦理论在工程应用问题,通过拉索系统动力学方程的无量纲化,使得决定系统的唯一参数为名义长细比。绘制无量纲名义长细比-频率曲线,利用弦理论和刚性索理论的频率差异性,... 弦理论方法有效识别索力对拉索的评估具有重要意义。为解决拉索的弦理论在工程应用问题,通过拉索系统动力学方程的无量纲化,使得决定系统的唯一参数为名义长细比。绘制无量纲名义长细比-频率曲线,利用弦理论和刚性索理论的频率差异性,给出弦理论索力计算公式满足特定索力误差需求的适用范围。对于超出适用界限的部分,以频率误差上限为例,通过幂次函数推导出三参数频率修正公式和索力修正公式,在此基础上,提出一种无量纲体系下的索力识别算法。由文献算例,验证了索力修正公式的可行性,并应用于实桥测试中,索力识别误差均满足工程需求。结果表明:不同精度的频率误差曲线可满足弦理论特定的工程应用,为解决实际工程问题提供理论支撑;该修正公式简洁直观、形式统一,且理论误差在2%以内,可覆盖工程拉索名义长细比的适用范围。 展开更多
关键词 弦理论 无量纲体系 索力识别 修正公式
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深入探讨Java中的String类 被引量:1
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作者 李斌 王睿 何成芊 《长沙通信职业技术学院学报》 2009年第3期42-44,共3页
文章分析了java的String类的本质,在此基础上,对其创建原理作了更为详尽的阐述。
关键词 JAVA string string string对象创建
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基于String Kernel和KPCA的负实例语法特征提取算法
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作者 吕威 林文昶 +1 位作者 姚正安 李磊 《计算机工程与应用》 CSCD 北大核心 2009年第20期136-139,共4页
提出通过String Kernel方法把负实例语法数据库中的负实例转化成核矩阵,再用Kernel Principal Component Analysis(KPCA)对转换的核矩阵进行特征提取,进而可将原始负实例数据库按照这些特征分成多个容量较小的特征表。通过构造负实例特... 提出通过String Kernel方法把负实例语法数据库中的负实例转化成核矩阵,再用Kernel Principal Component Analysis(KPCA)对转换的核矩阵进行特征提取,进而可将原始负实例数据库按照这些特征分成多个容量较小的特征表。通过构造负实例特征索引表设计了一个分类器,待检查的句子通过此分类器被分配到某个负实例特征表里进行匹配搜索,而此特征表的特征属性数和记录数要远远小于原始负实例数据库中的相应数目,从而大大提高了检查的速度,同时不影响语法检查的精度。通过比较测试,可看出提出的方法在保证语法检查精确度的同时有更快的速度。 展开更多
关键词 string KERNEL 核主成分分析 负实例 特征提取
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