Radislav Smid

Radislav Smid
Czech Technical University in Prague | ČVUT · Department of Measurement

Ph.D.

About

137
Publications
14,086
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820
Citations
Additional affiliations
January 2004 - present
České vysoké učení technické v Praze

Publications

Publications (137)
Article
The mass flow rate inside Heating, Ventilation, and Air-Conditioning (HVAC) units provides important information for Fault Detection and Diagnosis (FDD) and for performance monitoring. Most commercial units are not equipped with physical flow rate sensors, and virtual sensors (VS) offer an alternative that provides improved FDD performance. This pa...
Conference Paper
This article show the results of the synthesis of the ultraviolet measurement system using photodiode. It was synthesized the generalized structure of the system and the scheme of its measurement channels. The measurement accuracy is increased by transition to individual conversion functions as a photodiode as well as measurement scheme. It is also...
Conference Paper
The algorithm of the program was created to approximate the output signal of multisensor (MS) using the functional dependency of MS output voltage from MS operating frequency for a fixed thickness of tested films, the output voltage of the MS film thickness at a fixed frequency. The MS data obtained by sine wave eddy current measurement. It is inve...
Article
Full-text available
The early alert monitoring system for an effective scheduled maintenance strategy based on a wireless technology requires reliable transfer of the diagnostic information between the sensor and the gateway. This paper presents an industrial wireless sensor network (IWSN)-based machine condition monitoring (MCM) system capable of overcoming a false i...
Article
Full-text available
Results of studying the neural network method are presented to reduce the amount of calibration points for the multisensor (MS), in particular for the photodiode. This allows transmitting to the MS individual conversion function and provides the high accuracy of measurement. The structure of synthesized information-measuring system and its measurin...
Article
Full-text available
This paper introduces a novel framework for industrial wireless sensor networks (IWSNs) used for machine condition monitoring (MCM). Our approach enables the use of state-of-the-art computationally intensive classifiers in computationally weak sensor network nodes. The key idea is to split data acquisition, classifier building and training, and the...
Conference Paper
An improved algorithm of intelligent data processing by integrating the modified identification method of individual characteristic curve along with the adaptive neuro-fuzzy inference system (ANFIS) was proposed. The results of data prediction with training the ANFIS system and the different number of training epochs are described. The proposed app...
Article
An approach of multisensor signals processing at microprocessor or 8 bit microcontrollers is showed in this paper. This approach is based on multisensor individual conversion function or individual characteristic curve identification method with using of neural networks. It allow to reduce an amount of calibration points and increase the precision...
Article
Full-text available
This paper uses a linear transformer model to investigate the effect of the lift-off on the results of the thickness measurement of nonferromagnetic metallic plates. The transformer model previews that the time derivative of the magnetization curves obtained for different gaps between the excitation coil and the plate should intercept in a single p...
Data
two-layer aluminium aircraft structure with rivets, two notches below the rivets in the first layer (width 0.2 mm, length l_f=2.5 mm, angle 90 deg and 30 deg) and two in the second layer (width 0.2 mm, length l_f=2.5 mm and 5 mm, angle 90 deg), two defect-free rivets, The complete description of samples can be found in the article: R. Smid et al....
Data
four-layer aluminium structure (layer thickness 2,5 mm) with rivets containing 4 notches (width 0.2 mm, length l_f=2.5 mm, angle 90 deg ) below the rivets in the first, second, third or fourth layer, four defect-free rivets, The complete description of samples can be found in the article: R. Smid et al. , Automated Classification of Eddy Current S...
Data
stainless steel sample, 150 records, notches of width 0.2 mm, depth 1, 3 and 5 mm, both perpendicular and 45 deg orientation. The complete description of samples can be found in the article: R. Smid et al. , Automated Classification of Eddy Current Signatures during Manual Inspection, NDT&E International 38 (2005) pp. 462-470 Datasets are made fr...
Data
aluminium sample, 240 records, notches of width 0.3 mm, depth 0.4, 0.7, 1, and 1.5 mm perpendicular, depth 0.4, 0.7, 1, and 1.5 mm with an angle of 30 deg , 0.7, 1 and 1.5 mm with an angle of 60 deg and 1.5 mm with an angle of 45 deg, The complete description of samples can be found in the article: R. Smid et al. , Automated Classification of Eddy...
Article
Goal of this paper is to develop the method identification of multisensors characteristic curve using neural networks and minimize the number of calibration points required to find an appropriate characteristic curve for the input-to-output relationship of multisensors. A proposed original method illustrates how to improve the prediction accuracy o...
Article
Wireless approach to acquire diagnostic signals (vibration, temperature, input current etc.) from mechanical devices and their components could be more than an interesting alternative to conventional wire systems with a central data logger or analyser. It is evident that wirelessly mounted sensors bring benefits in easier installation, manipulation...
Article
In this paper we propose an improvement of methods for adaptive selection of frequency bands containing transients which indicate the presence of the dominant resonant modes of rolling bearing faults using niching genetic algorithm optimization. The main aim of this approach is to diagnose the condition of the bearings and to be able to recognize f...
Conference Paper
An important issue in ultrasonic nondestructive testing is the detection of flaw echoes in the presence of background noise created by instrumentation and by clutter noise. Signal averaging, autoregressive analysis, spectrum analysis, matched filtering and the wavelet transform have all been used to filter noise in ultrasonic signals. Widely-used w...
Conference Paper
Enhancing signal of interest over a noise level represents a common task for signal processing methods used in measurement systems. Digital filters are used for frequency band limited signals as a common signal of interest enhancement tool. If is the information localised not only in frequency domain but also in a limited time window within the sig...
Article
Offline processing of acoustic emission (AE) signal waveforms recorded during a long-term AE monitoring session is a challenging problem in AE testing area. This is due to the fact that today's AE systems can work with up to hundreds of channels and are able to process tens of thousands of AE events per second. The amount of data recorded during th...
Article
Full-text available
This paper describes a pulsed eddy current (PEC) based non-destructive testing system used for experimental evaluation of material thickness and properties. Both classical and modern sensing methods of magnetic field have been carried out. An inductive as well as a giant magnetoresistive sensor based (GMR) probe have been used for sensing and the r...
Article
An important issue in ultrasonic nondestructive testing is the detection of flaw echoes in the presence of background noise created by instrumentation and by clutter noise. Signal averaging, autoregressive analysis, spectrum analysis, matched filtering, and the wavelet transform have all been used to filter noise in ultrasonic signals. Widely-used...
Article
Direct evaluation of ultrasonic signals requires data analyses with an acceptable level of noise. Ultrasonic signals represent a specific category of time domain signals to be analyzed. In order to increase a difference between the level of noise and the amplitude of the ultrasonic pulse a suitable method for signal filtering has to be used. Within...
Article
Wireless sensor networks are perspective tools for machine condition monitoring. Output of wireless sensor node is affected by several degradations (sensor aging) and noises from various sources (impulsive noise from switching of inductive loads, internal electronic noise etc ). We propose a weak redundancy approach to increasing the sensor system...
Article
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 appli...
Article
In ultrasonic non-destructive testing of materials with a coarse-grained structure the scattering from the grains causes backscattering noise, which masks flaw echoes in the measured signal. Several filtering methods have been proposed for improving the signal-to-noise ratio. In this paper we present a comparative study of methods based on the wave...
Article
This paper is focused on evaluation of genetic algorithm based methods used to separate vibrations produced by tapered rolling bearings. The vibrations of tapered rolling bearings are strongly affected by the value of load forcing on the bearings. This influence is needed to be inspected. In this case the acquired signal contains significant distur...
Article
In the field of low flux optical measurements, the development and use of large area silicon detectors is becoming more frequent. The current/voltage conversion of their photocurrent presents a set of problems for traditional transimpedance amplifiers. The switched integration principle overcomes these limitations. We describe the development of a...
Conference Paper
The goal of this paper is to show the result of the real measurement with EMAT system in the aviation industry. Common nondestructive evaluation (NDE) techniques used in the field are the eddy current and the ultrasound inspection. EMAT (Electro-Magnetic Acoustic Transducers) system is a combination of these two methods and exhibit an advantage in...
Article
Full-text available
This paper deals with signal processing for vibration analysis of the gear transmission. The main goal was localization of the best measuring point on the gearbox housing, which could provide the highest sensitivity to gearwheels vibration. Vibration measured at some selected points on the gearbox housing was analysed using methods of spectral anal...
Article
This paper presents a statistical technique to enhance vibration signals measured by laser Doppler vibrometry (LDV). The method has been optimised for LDV signals measured on bearings of universal electric motors and applied to quality control of washing machines. Inherent problems of LDV are addressed, particularly the speckle noise occurring when...
Article
This paper evaluates methods used for separating vibrations produced by a gear transmission from the vibration signal acquired on the gearbox. The paper presents a novel method for evaluating the algorithms used for this separation. The evaluation method takes into account the statistical reliability of the results achieved on multiple sets of sign...
Conference Paper
Full-text available
This document deals with rotating machinery vibration analysis in order to separate vibrations produced by rolling bearings. The vibration signals were filtered using different Wiener filters. The paper is focused on comparison of efficiency which can be reached by usage of different Wiener filter estimation methods. The Wiener filter estimation me...
Conference Paper
This paper deals with image-based displacement measurement. The correlation method of displacement measurement computes the cross-correlation function from two images captured by a CCD camera. The shift level is then determined by the position of the maximum value of the cross-correlation function. If the cross-correlation function is computed dire...
Conference Paper
Full-text available
In this paper the cross-correlation and phase-shift techniques are used for material thickness estimation. The cross-correlation is used to measure the time a transmitted signal takes to arrive at the receiver or the time between two successive received signals (multiple echoes). Whereas the phase-shift technique measures the time delay (less than...
Article
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 sign...
Conference Paper
Full-text available
In this paper, a new method to enhance vibration signals measured by Laser Doppler Vibrometry (LDV) is proposed. The method consists of two stages of processing. The first stage is intended to reduce the speckle noise, an inherent problem of LDV when rough surfaces are measured. The speckle noise causes amplitude dropouts, resulting in undesired "s...
Article
Full-text available
This paper is concerned with analysis of vibration signals measured by Laser Doppler Vibrometry (LDV) for the purpose of quality con- trol on production lines. A new method has been developed in order to avoid the speckle noise occurring when rough surfaces are measured by LDV. The method has been embedded in an automatic test station for diagnosti...
Article
Full-text available
In ultrasonic non-destructive testing it is very difficult to detect flaws in materials with coarse-grain structure. The ultrasonic signals measured on these materials contain echoes which are very similar to fault echoes. These echoes arise from grains which are contained in the material. For the detection of flaws various methods for suppressing...
Conference Paper
In general the ultrasonic testing is used for flaw detection and localization in tested materials. The flaws in materials are commonly characterized in measured ultrasonic signals by faults echoes. In the case of materials with coarse-grained structure the ultrasonic signal contains undesirable echoes caused by the scattering from these grains cons...
Article
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 sta...
Article
This article presents a novel method for automatic evaluation of flaws during a manual eddy current (EC) inspection procedure. In manual scanning, a signal related to impedance change in the complex plane is affected by large and unpredictable variations of scanning speed and alterations of probe position. This paper introduces a robust EC signal n...
Article
Full-text available
Available from https://ojs.cvut.cz/ojs/index.php/ap/article/download/782/614
Article
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...
Conference Paper
Full-text available
The article describes methodology that has been developed for verification of measurement systems for voice transmission quality. Particular attention is given to testing of measurement algorithm implementation.
Conference Paper
In ultrasonic defectoscopy it is very difficult to detect flaws in materials with coarse-grain structure. Measured ultrasonic signal contains echoes from flaw and echoes from grains included in material. These echoes characterized noise have to be cancelled. A common source of noise is electronic circuitry, which is used for processing of the ultra...
Article
Full-text available
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 transf...
Conference Paper
Full-text available
The paper deals with the estimation of the relation between speech transmission quality and average call duration for a given network and portfolio of customers. It uses non-intrusive speech quality measurements on live speech calls. The basic idea behind this analysis is an expectation that the average call duration is higher for calls of a good q...
Conference Paper
Planar shape description became an important procedure in automated microscopy, biomedical database searching etc. We propose a shape description method based on wavelet packets applied on parameterized object contour. This method allows the multiscale description and automated features selection for various applications. The proposed method was us...
Conference Paper
Full-text available
This article identifies several areas of possible reduction of processing power requirements of the PESQ algorithm (ITU-T P.862). As a result, PDA-based implementation of PESQ-based speech transmission quality measurement system for GSM networks is presented and required computational times are discussed.
Conference Paper
Full-text available
A new method for objective voice quality measurements is described in the article. It is based on wavelet transformation that enables intrinsically also time localisation of eventual impairments. In comparison with other methods (based on P.861 and P.862 algorithms), the described method saves about one half of operations needed for achievement of...