The aerodynamic characteristics of train/vehicles under cross winds depend on not only the shapes of the vehicles but also those of infrastructures. Accordingly three kinds of wind tunnel tests were made to evaluate the aerodynamic characteristics of typical configurations of the vehicles on typical configurations of infrastructures such as bridges and embankments. The main results obtained from the wind tunnel tests are summarized below. 1. The aerodynamic side force coefficient of the vehicle increases more as the thickness of the bridge girder becomes larger. It also increases more as the roof of the vehicle becomes edgier. 2. The aerodynamic characteristics of the vehicle on the embankment depend on the distribution of the boundary layer on the ground. The aerodynamic side force coefficient of the vehicle on a high embankment is larger than that on a low embankment.

Aerodynamic Characteristics of Train/Vehicles under Cross Winds

Acoustic beamforming for noise source localization - Reviews, methodology and applications

A novel method is proposed for quantitative and localization diagnosis of a bearing outer ring defect in this paper. This method aims to distinguish these defects with different angular positions and different sizes based on the natural multiples of the ball angular spacing. Defects that differ in size by natural multiples of the ball angular spacing will have the same time interval, which may lead to misdiagnosis. Distinguishing such defects accurately is the goal for some industries. Therefore, the synchronized signal in the vertical and horizontal directions of the bearing systems with different angular positions and different size defects are quantitatively analyzed based on the presented five indices to explore the mechanism and method of distinguishing these defects. The simulation and experimental results show that the vertical–horizontal synchronized root mean square (VHSRMS) index can distinguish such defects effectively, and the defect angle position can be diagnosed using the VHSRMS–1 . More importantly, the VHS analysis method expands the location of the outer ring defect to 265–275° in quantitative diagnosis and realizes the localization diagnosis of the defect angle position. The research results provide a new approach and method for quantitative and localization diagnosis of a defective bearing.

Quantitative and Localization Diagnosis of a Defective Ball Bearing Based on Vertical–Horizontal Synchronization Signal Analysis

An Active Disturbance Rejection Control (ADRC) scheme is proposed for a trajectory tracking problem defined on a nonfeedback linearizable Furuta Pendulum example. A desired rest to rest angular position reference trajectory is to be tracked by the horizontal arm while the unactuated vertical pendulum arm stays around its unstable vertical position without falling down during the entire maneuver and long after it concludes. A linear observer-based linear controller of the ADRC type is designed on the basis of the flat tangent linearization of the system around an arbitrary equilibrium. The advantageous combination of flatness and the ADRC method makes it possible to on-line estimate and cancels the undesirable effects of the higher order nonlinearities disregarded by the linearization. These effects are triggered by fast horizontal arm tracking maneuvers driving the pendulum substantially away from the initial equilibrium point. Convincing experimental results, including a comparative test with a sliding mode controller, are presented.

Linear active disturbance rejection control of underactuated systems: the case of the Furuta pendulum

This paper integrates various ideas about the tensor product (TP) model transformation into one conceptual framework and formulates it in terms of the Takagi-Sugeno (T-S) fuzzy model manipulation and control design framework. Several new extensions of the TP model transformation are proposed, such as the quasi and “full,” compact and rank-reduced higher order singular-value-decomposition-based canonical form of T-S fuzzy models, and the bilinear-, multi, pseudo-, convex-, partial TP model transformations. All of these extensions together form the generalized TP model transformation, which provides an effective tool to freely and readily manipulate the antecedent sets and rules of T-S fuzzy models and also provides main fuzzy rule component analysis, as well as a means for complexity and accuracy tradeoffs. It is demonstrated in this paper that the proposed manipulation forms a new, effective, and necessary optimization step of T-S fuzzy or polytopic models and linear-matrix-inequality-based control design, and can also decrease conservativeness. Identification techniques are typically constructed according to the available data and measurement set, as well as the type of system to be identified. As a result, they may not always provide good representations for control design frameworks. This paper demonstrates that the proposed TP model transformation is unique in that it bridges between various soft-computing-based identification techniques and T-S fuzzy model-based approaches. Finally, this paper proposes the multi-TP model transformation, which is a tractable and nonheuristic framework to verify the stability of the result of fuzzy or various soft-computing-based control designs. The multi-TP model transformation could provide an answer to the frequently emerging criticisms regarding the lack of mathematical stability verification techniques in the soft-computing-based control design. Control examples are provided in this paper.

The Generalized TP Model Transformation for T–S Fuzzy Model Manipulation and Generalized Stability Verification

The Furuta pendulum, or rotational inverted pendulum, is a system found in many control labs. It provides a compact yet impressive platform for control demonstrations and draws the attention of the control community as a platform for the development of nonlinear control laws. Despite the popularity of the platform, there are very few papers which employ the correct dynamics and only one that derives the full system dynamics. In this paper, the full dynamics of the Furuta pendulum are derived using two methods: a Lagrangian formulation and an iterative Newton-Euler formulation. Approximations are made to the full dynamics which converge to the more commonly presented expressions. The systemdynamics are then linearised using a Jacobian. To illustrate the influence the commonly neglected inertia terms have on the system dynamics, a brief example is offered.

/pdf/on-the-dynamics-of-the-furuta-pendulum-2appox1mp1.pdf

On the dynamics of the furuta pendulum

Varying stiffness and load distributions in defective ball bearings: Analytical formulation and application to defect size estimation

Aeroelasticity is a broad term that describes the often complex interactions between aerodynamics and structural mechanics. The active control of aeroelastic phenomena is of particular research interest as it can lead to a reduction in weight and an increase in performance of an airframe. For more background on the analysis and control of aeroelastic systems, the reader is referred to the article by Mukhopadhyay [1]. A two degree-of-freedom wing section that is allowed to pitch and plunge due to supporting translational and torsional springs has often been used as a testbed for novel aeroelastic control methodologies. Two such apparatus are commonly used for the experimental validation of these methodologies; the Benchmark Active Control Technologies (BACT) wing [1, 2], and the Nonlinear Aeroelastic Test Apparatus (NATA) [3, 4]. This work focusses on the NATA platform, and presents an improved dynamic model along with a dynamic-less state-feedback Linear Parameter Vary-

Linear-Parameter-Varying Control of an Improved Three-Degree-of-Freedom Aeroelastic Model

Three-dimensional beamforming of dipolar aeroacoustic sources

Beamforming is a popular method of acoustic source localisation using an array of microphones. When beamforming over a plane or a series of planes, these microphone arrays are often two-dimensional sparse patterns of various designs. The design of these patterns is non-trivial, and influences the achievable resolution, also referred to as the beamwidth, and the Maximum Sidelobe Levels (MSL), a measure of the ability of the array to reject sources that the array is not focussed on. Although recent deconvolution techniques such as DAMAS aim to remove properties of the array from the results of beamforming, in practice the properties of the array will still influence the quality of the results. For this reason, it is important that the array exhibit good resolution and MSL for the intended beamforming application. In this paper, several popular two-dimensional array patterns such as the patented Underbrink and B&K spirals, as well as Doherty spirals and log-spirals are critically compared for both resolution and MSL for a variety of source locations, including both near-field (spherical propagation) and far-field (planar propagation) sources. Each array compared has an aperture of 1m, and uses 63 microphones in a typical arrangement found for each of the types. As array resolution scales linearly with wavelength, the resolution is calculated at a single frequency of 3 kHz, and normalised against wavelength. The MSL levels are calculated at the one-third octave band centre frequencies from 1‐31:5 kHz. Results show that the Underbrink design outperforms other array patterns in both resolution and MSL over the majority of frequencies analysed.

/pdf/a-comparison-of-popular-beamforming-arrays-34kjhugqqt.pdf

Zebb Prime

Papers

On the dynamics of the furuta pendulum

Varying stiffness and load distributions in defective ball bearings: Analytical formulation and application to defect size estimation

Linear-Parameter-Varying Control of an Improved Three-Degree-of-Freedom Aeroelastic Model

Three-dimensional beamforming of dipolar aeroacoustic sources

A comparison of popular beamforming arrays