System for 3D Visualization of Flaws for Eddy Current Inspection

This paper presents a novel method for 3D visualization of flaws detected during Eddy Current (EC) inspection. The EC data was acquired using an automated scanning system equipped with precise eddy current probe positioning. The method was tested on a single frequency instrument with an absolute probe. The EC inspection procedure is implemented statically by registering the operating point of the instrument at each equidistant point on a tested object.The paper describes a data processing method based on the Fourier transform enabling 3D visualization of flaws. This three-dimensional image of the result of a scan enables the position of flaws to be determined, and the size and bevel (angle to the surface) of each detected flaw to be estimated. This research investigated flaws rising from the surface of the tested object, and flaw depth was not evaluated in this work. This method of visualization is simple to implement and is currently targeted for application in EC scanning devices.

Condition Indicators for Gearbox Condition Monitoring Systems

Condition monitoring systems for manual transmissions based on vibration diagnostics are widely applied in industry. The systems deal with various condition indicators, most of which are focused on a specific type of gearbox fault. Frequently used condition indicators (CIs) are described in this paper. The ability of a selected condition indicator to describe the degree of gearing wear was tested using vibration signals acquired during durability testing of manual transmission with helical gears.

Signal Separation in Ultrasonic Non-Destructive Testing

In ultrasonic non-destructive testing the signals characterizing the material structure are commonly evaluated. The sensitivity and resolution of ultrasonic systems is limited by the backscattering and electronic noise level commonly contained in the acquired ultrasonic signals. For this reason, it is very important to use appropriate advanced signal processing methods for noise reduction and signal separation. This paper compares algorithms used for efficient noise reduction in ultrasonic signals in A-scan. Algorithms based on the discrete wavelet transform and the Wiener filter are considered. Part of this paper analyses and applies blind source separation, which has never been used in practical ultrasonic non-destructive testing. All proposed methods are evaluated on both simulated and acquired ultrasonic signals.

Signal-to-Noise Ratio Improvement based on the Discrete Wavelet Transform in Ultrasonic Defectoscopy

In ultrasonic testing it is very important to recognize the fault echoes buried in a noisy signal. The fault echo characterizes a flaw in the material. An important requirement on ultrasonic signal filtering is zero-time shift, because the position of ultrasonic echoes is essential. This requirement is accomplished using the discrete wavelet transform (DWT), which is used for reducing the signal-to-noise ratio. This paper evaluates the quality of filtering using the discrete wavelet transform. Additional computer simulations of the proposed algorithms are presented

Gearbox Condition Monitoring Using Advanced Classifiers

New efficient and reliable methods for gearbox diagnostics are needed in automotive industry because of growing demand for production quality. This paper presents the application of two different classifiers for gearbox diagnostics – Kohonen Neural Networks and the Adaptive-Network-based Fuzzy Interface System (ANFIS). Two different practical applications are presented. In the first application, the tested gearboxes are separated into two classes according to their condition indicators. In the second example, ANFIS is applied to label the tested gearboxes with a Quality Index according to the condition indicators. In both applications, the condition indicators were computed from the vibration of the gearbox housing.

Stresses in silos: Comparison between theoretical models and new experiments

We present precise and reproducible mean pressure measurements at the bottom of a cylindrical granular column. If a constant overload is added, the pressure is linear in overload and nonmonotonic in the column height. The results are {\em quantitatively} consistent with a local, linear relation between stress components, as was recently proposed by some of us. They contradict the simplest classical (Janssen) approximation, and may pose a rather severe test of competing models.Comment: 4 pages, 2 figures, final version to appear in Phys. Rev. Let

Identifying Ionic and Electronic Charge Transfer at Oxide Heterointerfaces

The ability to tailor oxide heterointerfaces has led to novel properties in low-dimensional oxide systems. A fundamental understanding of these properties is based on the concept of electronic charge transfer. However, the electronic properties of oxide heterointerfaces crucially depend on their ionic constitution and defect structure: ionic charges contribute to charge transfer and screening at oxide interfaces, triggering a thermodynamic balance of ionic and electronic structures. Quantitative understanding of the electronic and ionic roles regarding charge-transfer phenomena poses a central challenge. Here, the electronic and ionic structure is simultaneously investigated at the prototypical charge-transfer heterointerface, LaAlO3/SrTiO3. Applying in situ photoemission spectroscopy under oxygen ambient, ionic and electronic charge transfer is deconvoluted in response to the oxygen atmosphere at elevated temperatures. In this way, both the rich and variable chemistry of complex oxides and the associated electronic properties are equally embraced. The interfacial electron gas is depleted through an ionic rearrangement in the strontium cation sublattice when oxygen is applied, resulting in an inverse and reversible balance between cation vacancies and electrons, while the mobility of ionic species is found to be considerably enhanced as compared to the bulk. Triggered by these ionic phenomena, the electronic transport and magnetic signature of the heterointerface are significantly altered

Sensitivity of the stress response function to packing preparation

A granular assembly composed of a collection of identical grains may pack under different microscopic configurations with microscopic features that are sensitive to the preparation history. A given configuration may also change in response to external actions such as compression, shearing etc. We show using a mechanical response function method developed experimentally and numerically, that the macroscopic stress profiles are strongly dependent on these preparation procedures. These results were obtained for both two and three dimensions. The method reveals that, under a given preparation history, the macroscopic symmetries of the granular material is affected and in most cases significant departures from isotropy should be observed. This suggests a new path toward a non-intrusive test of granular material constitutive properties.Comment: 15 pages, 11 figures, some numerical data corrected, to appear in J. Phys. Cond. Mat. special issue on Granular Materials (M. Nicodemi Editor