世界上独一无二的传感器:Z-元件

本文介绍了由俄国传感器专家V.ZOTOV教授发明并生产的一种 新型传感器:Z—元件的工作原理、应用及特点.该元件与通常的传感器霍尔夫元件相比,无需前置放大和A/D转换器,便可直接输出大幅值脉冲数字信号.它可非接触式测量,体积小,功耗低,抗噪强,并可制成测温、测湿、测压力、光强、甚至测α、β、γ射线等各种物理量的Z—元件系列,堪称当今世界上独一无二的高品质传感器.

基于AT89C51恒速控制系统的设计

系统设计主要利用单片机AT89C51和霍尔夫器件。主要介绍了用PWM脉宽频率调制技术。通过霍尔夫器件为速度反馈系统,用来反馈给单片机,而后经过单片机调整以实现恒速。

Galerkin solution of Winkler foundation-based irregular Kirchhoff plate model and its application in crown pillar optimization

Irregular plates are very common structures in engineering,such as ore structures in mining.In this work,the Galerkin solution to the problem of a Kirchhoff plate lying on the Winkler foundation with two edges simply supported and the other two clamped supported is derived.Coordinate transformation technique is used during the solving process so that the solution is suitable to irregular shaped plates.The mechanical model and the solution proposed are then used to model the crown pillars between two adjacent levels in Sanshandao gold mine,which uses backfill method for mining operation.After that,an objective function,which takes security,economic profits and filling effect into consideration,is built to evaluate design proposals.Thickness optimizations for crown pillars are finally conducted in both conditions that the vertical stiffness of the foundation is known and unknown.The procedure presented in the work provides the guidance in thickness designing of complex shaped crown pillars and the preparation of backfill materials,thus to achieve the best balance between security and profits.

Implementation technology of Kirchhoff demigration

Demigration refers to directly applying a specific imaging technique to a migrated section. It is applied primarily to seismic data mapping. In a previous research study, a time-efficient implementation technology of demigration was expounded. In the present study, the Fast Marching Method （FMM） used for traveltime computation in the isochrone-staek demigration, is developed. Furthermore, other key techniques （ such as selection of aperture and antialiasing filtering factor） are analyzed in detail. Besides, the detail implementation method and program flow are given, which is shown their good computational efficiency and high-quality demi- gration effect. This implementation technique is illustrated with both the V（z） model and Marmousi model. It provides a basic method for implementing demigration in the application of seismic data mapping.

Helical Configurations of Elastic Rods in the Presence of Interfacial Traction

The Kirchhoff thin elastic rod models are always the important basis to explore the configuration mecha- nism of the flexible structures in both the macroscopic and microscopic scale. As a continuum model of DNA, a thin elastic rod subjected to interfacial interactions is used to investigate the helical equilibrium configuration of DNA in salt solution. In this paper, the Kirchhoff＇s equations in the presence of interracial traction and the free energy density functions of different configurations are studied. The transition formula of the free energy between B-DNA and Z- DNA is obtained, and the results show that the free energy of the transition is mainly determined by the salt concentra- tion, which agrees well with the experimental data.

Corona noise model of high-voltage AC transmission lines and engineering applications

In order to predict the levels of corona noise from high-voltage alternating current （AC） transmission lines, the mechanism of corona noise and the corresponding theoretical prediction model are investigated. On the basis of Drnde model, the motion of positive and negative ions produced by high-voltage corona is analyzed, and the mechanism of corona noise is discovered. The theoretical prediction model is put forward by using Kirchhoff formula, which is verified by the well agreement between our result and others＇ , considering the case of three- phase single lines. Moreover, the calculation results show that for both single and bundled lines, the sound pres- sure level of the typical frequency, i.e. twice the power frequency, attenuates slowly and leads to an obviously in- terferential phenomenon near the transmission lines, but the level of the bundled lines is smaller than that of the single ones under the same transmission voltage. Based on the mechanism of corona noise and the prediction model, it is obvious that bundled lines and/or increased line radius can be adopted to reduce corona noise in the practical engineering applications effectively. This model can also provide a theoretical guidance for the high-volt- age AC transmission line design.

Graph-Theoretic Approach to Network Analysis

Networks are a class of general systems represented by becomes a weighted graph visualizing the constraints imposed their UC-structure. Suppressing the nature of elements the network by interconnections rather than the elements themselves. These constraints follow generalized Kirchhoff＇s laws derived from physical constraints. Once we have a graph; then the working environment becomes the graph-theory. An algorithm derived from graph theory is developed within the paper in order to analyze general networks. The algorithm is based on computing all the spanning trees in the graph G with an associated weight. This weight is the product ofadmittance＇s of the edges forming the spanning tree. In the first phase this algorithm computes a depth first spanning tree together with its cotree. Both are used as parents for controlled generation of off-springs. The control is represented in selecting the off-springs that were not generated previously. While the generation of off-springs, is based on replacement of one or more tree edges by cycle edges corresponding to cotree edges. The algorithm can generate a frequency domain analysis of the network.

Mobile robot simultaneous localization and map building based on improved particle filter

We present an investigation into the use of pan tilt zoom camera and sonar sensors for simuhaneous localization and mapping with artificial colored landmarks. An improved particle filter is applied to estimate a posterior of the pose of the robot, in which each particle has associated it with an entire map. The distributions of landmarks are also represented by particle sets, where separate particles are used to represent the robot and the landmarks. Hough transform is used to extract line segments from sonar observations and build map simultaneously. The key advantage of our method is that the full posterior over robot poses and landmarks can be nonlinearly approximated at every point in time by particles. Especially the landmarks are affixed on the moving robots, which can reduce the impact of the depletion problem and the impoverishment problem produced by basic particle filter. Experimental results show that this approach has advantages over the basic particle filter and the extended Kalman filter.

假如你有一个男孩儿

奇妙的男孩世界在一篇题为"男孩是由什么做的?"文章中,记者葆拉·格雷·亨克引述了一位名叫梅格·麦肯齐的母亲的话,她把自己带大两个儿子的经历说成是"生活在龙卷风中"。"每天他们刚从学校回到家里,就满屋子乱奔乱窜。

Existence of solutions for a critical fractional Kirchhoff type problem in(49)R^N

This paper concerns with the existence of solutions for the following fractional Kirchhoff problem with critical nonlinearity：where （-△）s is the fractional Laplacian operator with 0 〈 s 〈 1, 2s＊ = 2N/（N - 2s）, N 〉 2s, p ∈ （1,2s＊）, θ∈ [1, 2s＊/2）, h is a nonnegative function and A is a real positive parameter. Using the Ekeland variational principle and the mountain pass theorem, we obtain the existence and multiplicity of solutions for the above problem for suitable parameter A 〉 0. Furthermore, under some appropriate assumptions, our result can be extended to the setting of a class of nonlocal integro-differential equations. The remarkable feature of this paper is the fact that the coefficient of fractional Laplace operator could be zero at zero, which implies that the above Kirchhoff problem is degenerate. Hence our results are new even in the Laplacian case.

Finite element corotational formulation for geometric nonlinear analysis of thin shells with large rotation and small strain

Based on the consistent symrnetrizable equilibrated （CSE） corotational formulation, a linear triangular flat thin shell element with 3 nodes and 18~ of freedom, constructed by combination of the optimal membrane element and discrete Kirchhoff trian- gle （DKT） bending plate element, was extended to the geometric nonlinear analysis of thin shells with large rotation and small strain. Through derivation of the consistent tangent stiffness matrix and internal force vector, the corotational nonlinear finite element equations were established. The nonlinear equations were solved by using the Newton-Raphson iteration algorithm combined with an automatic load controlled technology. Three typical case studies, i.e., the slit annular thin plate, top opened hemispherical shell and cylindrical shell, validated the accuracy of the formulation established in this paper.

Multi-hybrid method for investigation of EM scattering from inhomogeneous object above a dielectric rough surface

An iterative strategy combining Kirchhoff approximation （KA） method is presented in this paper to study the interactions between KA is applied to study scattering from underlying rough surfaces with the hybrid finite element-boundary integral （FE-BI） the inhomogeneous object and the underlying rough surface. whereas FE-BI deals with scattering from the above target. Both two methods use updated excitation sources. Huygens equivalence principle and an iterative strategy are employed to consider the multi-scattering effects. This hybrid FE-BI-KA scheme is an improved and generalized version of previous hybrid Kirchhoff approximation-method of moments （KA-MoM）. This newly presented hybrid method has the following advantages： （1） the feasibility of modeling multi-scale scattering problems （large scale underlying surface and small scale target）; （2） low memory requirement as in hybrid KA-MoM; （3） the ability to deal with scattering from inhomogeneous （including coated or layered） scatterers above rough surfaces. The numerical results are given to evaluate the accuracy of the multi-hybrid technique; the computing time and memory requirements consumed in specific numerical simulation of FE-BI-KA are compared with those of MoM. The convergence performance is analyzed by studying the iteration number variation caused by related parameters. Then bistatic scattering from inhomogeneous object of different configurations above dielectric Gaussian rough surface is calculated and the influences of dielectric compositions and surface roughness on the scattering pattern are discussed.

KIRCHHOFF TYPE EQUATIONS DEPENDING ON A SMALL PARAMETER

The authors prove some global existence results for equations of Kirchhoff type, i.e., nonlinearstretched string with nonlocal terms, depending on a parameter. This general setting includes the known results on the Kirchhoff equation with small data. Moreover, the authors can also handle some cases of degeneracy, which escaped earlier methods.

Observability Inequality for the Kirchhoff-Rayleigh Plate Like Equation in a Short Time

In this paper, for any given observation time and suitable moving observation domains, the author establishes a sharp observability inequality for the Kirchhoff-Rayleigh plate like equation with a suitable potential in any space dimension. The approach is based on a delicate energy estimate. Moreover, the observability constant is estimated by means of an explicit function of the norm of the coefficient involved in the equation.

Energy Decaying and Blow-Up of Solution for a Kirchhoff Equation with Strong Damping

The initial boundary value problem for a Kirchhoff equation with Lipschitz type continuous coefficient is studied on bounded domain.Under some conditions,the energy decaying and blow-up of solution are discussed.By refining method,the exponent decay estimates of the energy function and the estimates of the life span of blow-up solutions are given.