A hybrid method of component mode synthesis

A method is described for representing a structural component by means of its vibration modes. The modes used to describe the component may have the connection points to the remainder of the structure free, or fixed, or some points free and some points fixed. The modes may either be calculated or experimentally measured. Statically determined deflection influence coefficients may be used to improve the accuracy of the representation.

The advantages claimed for the method derive from the generality of the conditions under which the component modes are calculated (or measured). Thus the boundary conditions may be selected to optimize accuracy or, in the event that the modes have already been obtained, the method permits the available data to be used. Examples are presented that illustrate use of the method, and the significance of the improvements derived from static calculations.     

Design of a planar multibody dynamic system with ANCF beam elements based on an element-wise stiffness evaluation procedure

The absolute nodal coordinate formulation (ANCF) has been widely applied for large deformation analysis in flexible multibody dynamics. Although the formulation led to stable solutions for time integration under large rotations and deformations, excessive time consumption was recorded. The nonlinear relationship between the deformation and the internal force accounted for repeated adjustment to the force equilibrium state as the structure deformed. In this research, an equivalent model of the ANCF beam structure was constructed. The stiffness evaluation method was applied in an element-wise manner. In this model, the irrelevant parts were separated from those that relate to the displacements and design parameters enabling efficient updates of internal forces to achieve force equilibrium. Therefore, by using this model, optimization problems, in which displacements as well as design parameters keep changing can be efficiently approached. To verify the proposed method, two examples of optimization problems related to a free-falling pendulum and a slider-crank mechanism are demonstrated.     

Pencil beam pattern synthesis of subarrayed planar array

The improved nonlinear least‐square method is introduced into the synthesis of subarrayed planar array. This method changes the traditional least‐square method's shortness of being sensitive to its initial conditions. The whole antenna aperture is divided into several subarrays and the excitation amplitude of each subarray is optimized. This can reduce the cost and complexity of the antenna array through common use of components or mass production of identical subarrays. Some numerical experiments are provided to show the effectiveness of the proposed method. © 2014 Wiley Periodicals, Inc. Int J RF and Microwave CAE 25:56–65, 2015.     

Improved component mode synthesis and variants

This survey focuses on the two known model order reduction schemes being widely integrated in various commercial finite element packages, namely, the static and dynamic condensation methods. The advantages as well as the corresponding drawbacks have been extensively analyzed in several papers throughout the last decades. Based on combining the beneficial properties of the aforementioned methods, several alternative reduction methodologies are outlined in this paper, i.e., the generalized improved reduction system method, the generalized component mode synthesis and the improved component mode synthesis with its generalized version, which incorporate in a more efficient way the system’s inertia terms. Therefore, the associated error regarding higher frequency ranges of interest is better controlled. Basis of these methodologies is the so-called master and slave degrees of freedom partitioning, the right selection of which highly influences the reduced order model’s dynamics. The methods are tested and verified on a rather small three-dimensional bar structure and on the lever part of a turbocharger’s variable turbine geometry. Several reduced order models are generated by varying both the number of Craig–Bampton modes and the selection of the required master degrees of freedom. A comparison is conducted based on the modal criterion of the corresponding eigenvectors and the associated computation time required.     

Spurious results of the component mode synthesis

The natural frequencies and mode shapes of a bentbeam in flexure-torsion oscillation are examined using the modal synthesis technique. The problem involves six boundary constraint conditions and the effect of ignoring a number of these conditions are examined. The choice of generalized coordinates offer other variations in the problem. In all, 50 different cases are studied on the digital computer. These are compared with the exact solution and also with experimental results obtained in the laboratory.     

Hybrid component mode synthesis based on test derived data

A method of component mode synthesis in which a majority of the dynamic characteristics of individual components are determined by modal testing is described. For the purpose of testing, the component can be supported on a suitable number of rigid supports. Alternatively, the test can be carried out in a free–free configuration, in which very flexible cables are used to hold the component. In either case, a number of practical difficulties arise. A new approach to modal testing in which the fixed–fixed modes of the component are obtained from a test configuration in which the component is held by supports of arbitrary characteristics is described. A complete theoretical formulation is developed. Computer simulation studies are carried out to determine the sensitivity of the calculated mode shapes and frequencies of the assembled structure to the various measurement errors in modal testing. Some results from these studies are presented.     

基于旋转平面激光扫描测角的新型坐标测量系统

为了满足现代制造业中超大尺寸测量高效高精度的要求,以空间角度交汇测量原理为基础,提出了一种新的三维坐标测量系统.介绍了该系统的测量原理,分析了系统的几何模型.结合测量原理和结构对系统精度的影响,对系统的重要部件进行了结构设计分析,完成整个系统的设计.最后通过实验数据验证该系统的可行性,该系统在6m的测量距离精度可达±0.15 mm.     

Broadband conical beam antenna in planar environment

In this article, a substrate‐truncated microstrip circular patch antenna with shorting vias is proposed for X‐band applications. The bandwidth of the designed antenna is substantially increased by making two slots—one circular and another annular ring—at the top of the structure which actually helps in bringing two individual resonating frequencies closer to each other. The antenna is simulated using the Ansoft HFSS, and various parameters are optimized for better performance. The deigned structure is finally fabricated and tested, and the measured data fairly agree with the simulated results. The measured relative impedance bandwidth (|S₁₁| < ?10 dB) is found to be 28.5% (8.9‐11.85 GHz). The proposed antenna is behaving like a monopole with the radiated beam of conical shaped in the entire operating band having a maximum gain of 7.2 dBi.     

Interpolating sliding mode observer for a ball and beam system

ABSTRACT

A principle of interpolating sliding mode observer is introduced in this paper. The observer incorporates multiple linear observers through interpolation of multiple estimates, which is treated as a type of adaptation. The principle is then applied to the ball and beam system for observation of the slope of the beam from the measurement of the ball position. The linearised model of the ball and beam system using multiple linearisation points is developed. The observer dynamics implemented in Matlab/Simulink Real Time Workshop environment. Experiments conducted on the ball and beam experimental setup demonstrate excellent performance of the designed novel interpolating (adaptive) observer.     

Validation,performance, convergence and application of free interface component mode synthesis

During the past three decades the component mode synthesis methods were extensively presented in the literature. Unfortunately, it seems that no convergence criterion was clearly defined in the literature. A free interface method is presented in this paper and six test cases are used to evaluate the number of retained substructure modes necessary to ensure convergence. The approach is validated numerically and experimentally. Also, an application of the proposed free interface method to optimization design is presented.     

A posteriori error analysis of component mode synthesis for the elliptic eigenvalue problem

We develop a posteriori error estimates for the error associated with model reduction of elliptic eigenvalue problems using component mode synthesis (CMS). The estimates reflect to what degree each CMS subspace influence the overall error in the reduced solution. This allows for automatic error control through adaptive algorithms that determine suitable dimensions of each CMS subspace.     

对称分量法在掘锚机组保护系统中的应用

针对掘锚机组异步电动机故障诊断可靠性和准确性不高的问题,提出将对称分量法应用到掘锚机组保护系统中,实现不对称性过流故障诊断。将三相电压分解为正序分量、负序分量和零序分量,通过有源移相电路和相序判别电路判别主回路的相序,通过负序分量采集电路得到负序电压值,根据负序电流值判断故障及其类型。工业性试验结果表明,对称分量法的应用提高了掘锚机组保护系统的灵敏度、可靠性、准确性和智能化水平,降低了系统维护成本,同时提高了掘锚机组异步电动机的使用寿命和掘进工作面的掘进速度。     

Phase‐only synthesis of planar arrays using autocorrelation matching method

Autocorrelation matching method is proposed for phase‐only synthesis of power pattern of planar antenna arrays. This method is based on equating the autocorrelation coefficients of a planar array having a specified amplitude of excitations to those of a conventionally designed planar array. The effectiveness of the proposed method is verified by synthesis of pencil‐beam and flat‐top patterns.     

监控系统中多路视频的合成方法

给出一种使用FPCA和ARM实现4路视频采集存储功能的嵌入式系统设计方法,介绍了FPCA控制视频AD芯片TvP5154对模拟视频进行数字转换、多路ITU656格式的视频数据的抽取方法、视频数据的乒乓存储以及合成后的视频数据的重组发送。     

Methods that combine finite group theory with component mode synthesis in the analysis of repetitive structures

The static and dynamic calculations of symmetric mechanical structures are considered. This type of configuration is frequently found in rotary machines, turbomachines, parabolic antennas, spatial structures, etc. The objective of this study is to present two methods and a calculation code which takes this repetitivity into account in order to minimize the time and cost of predictive calculations. Both proposed methods are applicable to bidimensional and tridimensional problems with arbitrary loadings. They are based on the theory of linear representations of finite groups and a technique of component mode synthesis.     

The application of component mode synthesis for the dynamic analysis of complex structures using ADINA

This paper describes how a complex structure is divided into various kinds of substructures which are calculated independently using the ADINA program and, following this, the dynamic characteristics of the entire structure are recombined by the bi-consistent dynamic substructure method which is a free-interface method improved by the authors. Because both the displacement consistent of substructure interfaces and the interface force equilibrium are satisfied by the present method, all interface degrees of freedom in the synthesis equations can be eliminated. Several examples are presented to illustrate the effectiveness of the proposed method.     

Corner detection based on gradient correlation matrices of planar curves

An efficient and novel technique is developed for detecting and localizing corners of planar curves. This paper discusses the gradient feature distribution of planar curves and constructs gradient correlation matrices (GCMs) over the region of support (ROS) of these planar curves. It is shown that the eigen-structure and determinant of the GCMs encode the geometric features of these curves, such as curvature features and the dominant points. The determinant of the GCMs is shown to have a strong corner response, and is used as a “cornerness” measure of planar curves. A comprehensive performance evaluation of the proposed detector is performed, using the ACU and localization error criteria. Experimental results demonstrate that the GCM detector has a strong corner position response, along with a high detection rate and good localization performance.     

On the selection of the mode cut-off number in component mode reduction

Dynamic analysis of very large and complicated FE structures such as FE full-vehicle structures are mainly performed with synthesized, component mode-reduced sub-models with common interfaces. The theory of component mode reduction (CMR) is well known, but it is not a simple application in real-live analyses. One of its problems, discussed in this paper, has not appeared in literature or in commercial software releases and their reference guides yet, although, in advanced computer-aided engineering, most dynamic analysts are confronted with it. The problem is related to the mode cut-off number in CMR and its enormous influence on the components reduced representation and the response solution. The mode cut-off number is the number of retained mode shapes from the components in CMR and the frequency corresponding to the highest mode is called the cut-off frequency. Ultimately the response quantities in excited vibrations, predicted from the reduced order model, are only as good as the component modes and the system modes. A proper application of the CMR technique is one of the most important success factors in today’s analysis quality in the advanced product development process across many industries. Therefore, the mode cut-off number should be considered to be a measure of analysis quality. The paper illustrates the effect of the mode cut-off number in an example from automotive industry: CMR of a body-in-white component and system mode computation of the reduced system. A list of guide lines concludes the discussion and some proposals for a stable analysis process and optimal performance are also given.