数值的
- 与 数值的 相关的网络例句 [注:此内容来源于网络,仅供参考]
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In this topic, the dynamic analysis methods for piezoelectric vibrator are studied systematically based on the theoretical model, FEM numerical experimentation and FEM governing equation for given compound-mode vibrator, and some valuable conclusions are obtained. The main work accomplished is summarized as follows: 1.Elaborate the main modeling methods for piezoelectric vibrator and the significance and necessity to study the dynamic characteristics of piezoelectric vibrator which emphasize the urgency of this paper. 2.Take the bending deformation induced by piezoelectric ceramic as example, the energy transfer mechanism of electric energy to mechanical energy are analyzed; the motion and force transfer mechanism are analyzed for the longitudinal-bending vibrator. 3.Based on mode assumption and Hamilton principle, the coupling model of piezoelectric vibrator of linear USM is built; moreover, the equivalent circuit model is obtained and a coupling equation represents the relation between electric parameters and mechanical parameters is derived which provides foundation to match the vibrator and driving circuit. 4.Combine the constitutive equation of piezoelectric ceramic with elastic-dynamical equation, geometric equation in force field and the Maxwell equation in electric field and the corresponding boundary condition equation, the FEM control equation for piezoelectric vibrator of USM to solve dynamic electro-mechanical coupling field is established by employing the principle of virtual displacement. The equation lays the foundation to study the non-linear constitutive equation of piezoelectric ceramic driven by high-power. 5.Define the dynamic indexes of characteristic of vibrator and carry out variable parameters simulation by calculating the model parameters and the electric characteristics of vibrator are simulated according to the equivalent circuit model. By numerical experimentation, the working mode of vibration of vibrator and the shock excitation results of the working frequency band which provides the mode frequency to realize bimodal are analyzed. Detailed calculation of the electro-mechanical coupling field parameters is made by programming the FEM control equation.
本课题从理论模型、有限元数值试验、有限元控制模型等方面以复合振动模式振子为例对超声电机压电振子的动力学特性及其分析方法进行了全面系统地研究,得出了许多有价值的结论,主要概括如下: 1、阐述了目前针对超声电机压电振子的主要建模方法,对压电振子动态特性的研究意义和必要性进行了论述,突出了本文研究内容的迫切性; 2、以压电陶瓷诱发弹性体发生弯曲变形为例,分析了压电陶瓷通过诱发应变来实现机电能量转换的机理;对基于纵弯模式的压电振子的运动及动力传递机理进行了分析; 3、基于模态假定,利用分析动力学的Hamilton原理,建立了面向直线超声电机压电振子的机电耦合动力学模型,并据此建立了压电振子的等效电路模型,导出了电参量与动力学特性参量的耦合方程,为压电振子与驱动电路的匹配提供了依据; 4、从压电陶瓷的本构方程出发,综合力场的弹性动力学方程、几何方程、电场的麦克斯韦方程以及相应的边界条件方程,采用虚位移原理,建立了压电振子动态问题机电耦合场求解的有限元控制方程,为研究其大功率驱动下的非线性本构模型奠定了基础; 5、界定压电振子的动力学特性指标,对压电振子的机电耦合动力学模型参数进行计算及变参数仿真;依据等效电路模型,对压电振子的电学特性进行了仿真分析;通过有限元数值实验,对压电振子工作模态附近的模态振型及工作频率附近的频段进行了激振效果分析,找出了实现模态简并的激振频率;利用有限元控制方程,通过编程计算,对压电振子的力电耦合场参数进行了详细计算,得出了一些有价值的结论。
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During the four years study on the project, we develop a dynamical forecast model that describing the subtropical ridge surface. A new theory on the role of the land-sea thermal difference on the formation of the Subtropical High is advanced. It is concluded that in the summer subtropics over each continent and its adjacent ocean LO, SE, CO, and a double-dominant heating from west to east compose a LOSECOD heating quadruplet. The influence of the Eurasia continent on SH varies according to the seasonal variation. From the ideal numerical simulation it is shown the important role of the Eaiuan continent and the huge topography on the mechanism of formation and mantanence of the SH during the summer. It is verified by the numerical simulation that the extension of the subtropical continent into the tropics greatly enhances the " East Asian monsoon". Through the Rossby energy dissipation theory it is verified that the deep latent convective heating induces the onset of the South China Sea monsoon over the Bay of Bengal. The relationship and mechanism between the precipitaiton over the East Asia and the Subtropicla high is illustrated by the data. It is also found the close phase lock between the east-west shift of the SH and the disturbence of the east wind belt over the tropical troposphere. The interaction between the structure and activity feature of the SH and the Meiyu over the Yangtze-Huaihe river valley is revealed from the data. The numerical simulation verified the impact of the different SH pattern on the path of the typhoon.
本项目的研究发展了描述副热带高压脊面变化的动力模型,提出了夏季副热带地区四叶型非绝热加热分布型及相应环流拼图的创新理论;明确了大陆尺度的海陆热力差异在副热带高压形成中的作用;指出欧亚地形对副热带高压和气候的影响随季节变化而变化,通过数值试验证明春季青藏高原的感热加热对亚洲夏季风的爆发地点起了"锚定"的作用,进一步证实了副热带高压断裂和亚洲夏季风的最早爆发地点发生在孟加拉湾东岸;利用Rossby波能量频散理论证明了孟加拉湾深对流潜热释放诱导南海季风爆发的机制;揭示了东亚季风降水的季节内变化与西太副高的关系及机理;揭示了西太副高与东西风带中扰动之间的相互作用过程,指出西太副高的东西活动与热带对流层上空东风带扰动和中纬度西风带扰动的移动和锁相密切相关;研究了夏季淮河流域梅雨期间副高结构和活动特征及其与江淮暴雨的相互作用;验证了不同副热带高压形态对台风路径的不同影响;通过数值试验证明了欧亚大陆和青藏高原等大地形对副热带高压形成和维持的重要作用。
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The primary studying works and characteristics:1 To summarize reinforcing theory of cement mixing pile composite foundation2 To analyze the primary mechanics characters and changing rules of cement mixing pile, based on analysis of test data both indoor and outdoor.3 To discuss siding frictional resistance, ending resistance, ultimate bearing capacity of simple mixing pile and effectiveness factor of grouped piles, loading ratio of soil between piles under cushion cap of grouped piles and stress ratio of pile and soil and so on, and use many computation method and experimentation method to ensure bearing capacity of mixing piles composite foundation.4 To point out and analyze eight sides flaws and problems of the bearing capacity calculation method of mixing pile compositefoundation which ensured by national and normative method/ formula.5 To apply test results of loading tests and a few settlement observation data, use gray theory to predicate ultimate bearing capacity of deep mixing piles, actual example demonstrate engaging between theoretical predicted value and actual value.6 To apply groovy layerwise summation method to discuss entity piles method, double foundation method, equivalent layerwise summation method and consolidation theoretical method and so on, especially by combination of engineering example, use FEM to calculate or discuss the settlement and changing rules of composite foundation.7 To discuss problems of critical length of composite foundation by combination of engineering example and numerical analysis method, and analyze the contrast of critical length between simple pile load and most area load of composite foundation, not only critical length of composite foundation is relative to modulus ratio between piles and soil, but also upside load distribution area of composite foundation.
主要的研究工作与特色为:(1)总结了水泥搅拌桩复合地基的加固原理;(2)在对室内外试验资料进行统计分析的基础上,系统分析了搅拌桩水泥土的主要力学特性及其变化规律;(3)探讨了搅拌单桩的侧摩阻力、端阻力、极限承载力及群桩效率系数、群桩承台下桩间土荷载分担比及桩土应力比等,提出用多种计算方法并结合试验方法来综合确定搅拌桩复合地基的承载力;(4)明确指出和分析了按国家有关规范的方法确定搅拌桩复合地基承载力所存在的八个方面的缺陷与问题;(5)利用过去没有加载至破坏阶段的载荷试验成果和较少的沉降观测数据,尝试了用灰色理论预测深层搅拌桩的极限承载力,实例表明理论预测值与实测值吻合较好;(6)在常规分层总和法的基础上,探讨了复合地基沉降计算的实体墩基法、双层地基法、等效作用分层总和法、固结理论法等,特别是结合工程实例,用有限元数值计算等方法计算和讨论了搅拌桩复合地基的沉降及其变化规律;(7)结合工程实例,用数值分析方法探讨了复合地基临界桩长的问题,指出和分析了单桩荷载下的临界桩长与复合地基大面积荷载下的临界桩长存在很大的差别,复合地基的临界桩长不仅与桩土模量比有关,而且与复合地基上部荷载分布面积有关。
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Our results improve the former results. For periodic Jacobi matrix, some new spectral properties of periodic Jacobi matrix are given by studying the relationship of the eigenvalues of periodic Jacobi matrix and its n—1 principal submatrix. Applying these spectral properties, we present a necessary and sufficient condition for the solvability of an inverse problem of periodic Jacobi matrices and discuss the number and the relationship of its solutions. Furthermore, we propose a new algorithm to construct its solution and compare it with the former algorithms. As this inverse problem of periodic Jacobi matrix usually has multiple solutions as many other eigenvalue inverse problems, we study the uniqueness of this problem. And a necessary and sufficient condition is given to ensure its uniqueness, under which an algorithm is presented and the stability analysis is also given. Finally, we put forward a new inverse problem for periodic Jacobi matrix which has not been solved.
对周期Jacobi矩阵特征值反问题,通过研究周期Jacobi矩阵与其n-1阶主子阵特征值的关系,给出了周期Jacobi矩阵的一些新的谱性质;利用这些谱性质,研究了一类周期Jacobi矩阵特征值反问题,用新的方法推导出了该类特征值反问题有解的充分必要条件,并讨论了解的个数以及解与解之间的关系;此外,提出了一种新的构造周期Jacobi矩阵反问题解的数值算法,并与前人的算法做了一定比较;由于周期Jacobi矩阵特征值反问题和其他很多特征值反问题一样往往存在多个解,本论文给出了周期Jacobi矩阵反问题解唯一的充要条件,并发现周期Jacobi矩阵特征值反问题的解唯一当且仅当构造的矩阵满足一定的条件;在解唯一的情况下,给出了构造唯一解的数值算法,并做了相应的稳定性分析;最后,提出了一类新的有待于解决的周期Jacobi矩阵特征值反问题。
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The mechanism of instability wrinkling in the process based on minimum energy principle is revealed, uniform mathematic description of the wrinkling wave on the strip of in-plane bending is established, the internal and external energy is deduced by energy method, and a uniform criteria of internal and external wrinkling is established; then how to combine the criteria with the FEM simulation system to make the numerical prediction of wrinkling into reality is also resolved in the paper. The effects of the forming parameters on the deforming result are analyzed by the uniform predict criteria. The results show as follows: as the compress width increase, external wrinkling first come into being, then internal winkling do, and finally in-plane bend occur; the loading wedge angle increase, internal winkling first come into being, thenin-plane bend do, and finally external wrinkling occur; in-plane bend is possible to occur with a increase of the strain-hardening exponent and the strength coefficient; and the effect of the friction factor may be ignored.
2揭示了板带不均匀压下面内弯曲成形过程基于能量原理的失稳起皱机理,提出了统一的描述内外缘起皱波形的函数,采用变分法推导了服从该波形函数的内外缘起皱能,建立了统一的起皱预测准则;将新建立的统一的起皱预测准则引入到数值模拟系统IBS中,数值预测结果与实验结果的吻合较好;分析了成形过程各参数对起皱的影响规律:随着接触变形区宽度的逐渐增大,先是发生外缘起皱,然后发生内缘起皱,进而才出现稳定成形;随着实际加载楔角的增大,先是发生内缘起皱,然后发生稳定成形,进而出现外缘起皱;硬化指数和强化系数增大,易于稳定成形;摩擦因子对起皱的影响不明显;而且接触变形区宽度对起皱的影响最大。
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Judge clouds' effect on solar radiation by satellite cloud map gray scale values, therefore establish and confirm the relationship between them. Roughly acquire optical depth of clear sky and clouds from radiation station data and routine meteorological data of land surface, and the study the relationship between clouds' physical character and radiation....
通过卫星云图的计数值来判断云对辐射的作用,以此建立起它们之间的关系;利用地面观测资料和常规资料来粗略求取晴空大气和云光学厚度,进而研究云的物理属性与辐射关系;简单的获取地表与近地面大气之间的辐射关系,以此估算地表的反照率,和地表的净辐射;分析了卫星可见光、红外及水汽云图计数值和地面辐射之间关系,利用辐射传输公式来推倒和分析云对辐射的关系,试图建立起卫星测值与地表总辐射和净辐射之间的关系,并将晴空和有云的个例分开,分别建立并选出最佳模式,以此来估算地表的净辐射和总辐射。
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Through the analysis of different cross section flow field in cylinder of two-valve and four-valve diesel engine, the following conclusion can be obtained: The formation of intake swirl of two-valve diesel engine mainly is effected by an intense air flow ring zone near the radius from valve axis to cylinder axis, as the flow progresses down through the cylinder, the ring zone air flow expends to both side and finally forms an unified rigid rotating swirl motion.
2号缸盖的螺旋进气道产生的绕自身气门轴线的动量矩比1号缸盖的大,且切向气道的径向速度在前峰面上的数值比1号缸盖的速度数值大很多,因此,两进气道组合后的动量矩损失也大,所以虽然2号缸盖的两个进气道单独的涡流比都高于1号缸盖的两个进气道,但组合后的合成涡流比却是基本相同的。
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Information is stored in mass storage systems in large units called files. A typical file may consist of a complete text document, a photograph, a program, or a collection of data about the employees in a company. The physical properties of mass storage devices dictate that these files be stored and retrieved in multiple byte units. For example, each sector on a magnetic disk must be manipulated as one continuous string of bits. A block of data conforming to the physical characteristics of a storage device is called a physical record. Thus , a file stored in mass storage will typically consist of many physical records.
在大容积存储系统中,信息是以称为文件的大的单位存储的,一个典型的文件可以是一个全文本的资料,一张照片或一组关于公司员工的数值,大容积存储系统的物理特性表明,这些个文件是按照许多字节为单位存储的检索的,例如,磁盘上每个扇区必需作为一个持续的二进制位串进行操作,符合存储系统物理特性的数值块称为物理记录,因此储存安放在大容积存储系统中的文件通常包罗许多物理记录。
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By applying the sinusoidal wave mode to simulate the rugged surface of bridge deck,accounting for vehicle-bridge interaction and using Euler-Bernoulli beam theory, a coupling vibration model of vehicle-bridge system was developed. The model was solved by mode analyzing method and Runge-Kutta method, and the dynamic response and the resonance curve of the bridge were obtained. It is found that there are two resonance regions, one represents the main resonance while the other the minor resonance, in the reson...
通过用正弦波形模拟桥面的不平和考虑移动车辆-桥梁间的相互作用,在Euler_Bernoulli梁理论的基础上建立了一种车桥系统的耦合振动模型·利用模态分析法和Runge_Kutta法对模型进行数值求解,获得了车桥系统耦合振动的动态响应和共振曲线·发现车桥耦合振动的共振曲线中存在两个共振区域,一个反映主共振而另一个反映次共振·讨论了桥面不平、桥梁振型和车辆间的相互作用对系统振动的影响·数值结果表明,这些参数对系统振动的影响很大,桥面不平和振型对车桥系统耦合振动的影响不能忽略,设计车速应该远离临界车速
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The wave propagation and refraction of type "O" irregularities in the counter-electrojet conditions is investigated with a model electrojet in terms of the linear theory of the electrojet instability.
本文分析了反向赤道电射流条件下的不均匀性的对流放大特性。根据电射流不稳定性的线性理论,对一个分层均匀的电射流的模式的数值计算表明:在反向电射流条件下,电射流不均匀性有如下的特性:在波的传播过程中,在上电射流区内,波矢向下旋转,在下电射流区内,波矢向上旋转;在驱动电场E_D数值相同的情况下,反向电射流条件下的射线路径积分增长率r比正常电射流情况的要小得多。
- 推荐网络例句
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The split between the two groups can hardly be papered over.
这两个团体间的分歧难以掩饰。
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This approach not only encourages a greater number of responses, but minimizes the likelihood of stale groupthink.
这种做法不仅鼓励了更多的反应,而且减少跟风的可能性。
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The new PS20 solar power tower collected sunlight through mirrors known as "heliostats" to produce steam that is converted into electricity by a turbine in Sanlucar la Mayor, Spain, Wednesday.
聚光:照片上是建在西班牙桑路卡拉马尤城的一座新型PS20塔式太阳能电站。被称为&日光反射装置&的镜子将太阳光反射到主塔,然后用聚集的热量产生蒸汽进而通过涡轮机转化为电力