Papers by Keyword: Diagnostics

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Authors: Tomasz Lus
Abstract: The paper presents problems related to testing of the technical condition of high-speed marine diesel engines that are not equipped with indicated valves, as it is in the case of larger medium-and low-speed marine internal combustion engines. In this case, in assessment of technical condition of engine fuel injection system and valve gear system a vibration signals (in time / angle domain) analysis modified method called HFRT (High Frequency Resonance Technique) can be used. This method indirectly helps also to evaluate the fuel combustion process in the engine cylinders. The paper presents the theoretical basis of a modified HFRT method, physical implementation of the marine diesel engine system’s analyzer used for marine engines testing built at the Institute of Construction and Operation of Ships at Polish Naval Academy (PNA) in Gdynia. The paper also includes a description of the vibration signal processing methodology and examples of measurements made in the ships conditions for a few selected types of engines.
Authors: Alexandra I. Khalyasmaa, Stepan A. Dmitriev, Sergey E. Kokin
Abstract: This paper deals with power transformers technical state assessment based on technical diagnostics using Bayes method. Present a model for integral power transformers technical state assessment on the three types of technical diagnostics. Determining state of power transformers is based on expert judgment using the membership functions.
Authors: Predrag Jovančić, Dragan Medenica, Vladimir Milisavljević, Ivica Ristović
Abstract: Most common types of bucket wheels were analyzed by finite elements method in this paper. Also, relevant diagnostics parameters are defined for various constructions (stress concentration, deformation energy, distribution of potential and kinetic energy for main oscillation shapes). This approach enabled identification of weak spots and selection of such types of bucket wheel which are most suitable for specific working conditions on open cast mine.
Authors: Bogdan Pojawa
Abstract: The paper presents the results of study concerning the determination of operating characteristics of the examined engine in steady states. The study concerned main propulsion engines of an Oliver Hazard Perry class frigate operated by the Polish Navy. The studies were conducted in the ship's engine room when the ship was at sea. Operating characteristics were determined on the basis of the measurements recorded over the entire load range of the engine, from minimum to rated load. During the studies, the load of both engines of the ship was simultaneous and balanced. In order to facilitate the comparison of the operating characteristics of the tested engines, as well as to make a reference to various weather conditions, the data obtained was reduced to standard reference state. For the aforementioned characteristics approximation relations were determined using statistical analysis. The relations obtained may be utilized in energy modeling and simulations, as well as technical diagnostics concerning this kind of engines.
Authors: Pawel Stefaniak, Radosław Zimroz, Walter Bartelmus, Monika Hardygóra
Abstract: In the present fast-paced world of business in a highly competitive marketplace, the focus on increasing the efficiency of business processes seems to be a reasonable challenge. For this reason in order to optimize production costs, there is an increasing trend toward maximising the use of the operational capabilities of the equipment – technological line components – with the prevention of failure events and their consequences in the form of costly repairs or replacements. A condition-based maintenance (CBM) approach allows to globally monitor, maintain and control operation of the whole complex of equipment and/or processes. The CBM effectively supports decision-making process concerning their further use or determination of the optimum repair/replacement schedule. The presented decision support system is dedicated for an underground copper mine, where the network of belt conveyors is a critical part of the production process. Due to complexity of mechanical system, harsh mining environment and presence of many degradation factors, development of the effective CBM system seems to be justified. It requires the integration of data from different sources, adaptation of advanced data mining techniques, procedures or various diagnostic methods. Because of the multidimensional nature of diagnostic data and diversified technical configurations of the facilities, it was necessary to develop and implement multivariate analytical models based on artificial intelligence techniques. Consequently, it allows to achieve improvement of efficiency of transportation network and reduction of repairs costs and unplanned breakdowns. In this paper we will briefly refer to all these issues.
Authors: M.D. Duta, Manus Patrick Henry
Abstract: Two similar approaches are presented for performing consistency checking of measured data in cases where associated uncertainty values are provided. The key differences between the approaches concern the determination of a consistent subset, and the treatment of measured data deemed to fall outside that subset. The different approaches reflect the priorities of their respective domains of application, namely on-line sensor monitoring, and interlaboratory comparisons.
Authors: Vytautas Kazimieras Augustaitis, Vytautas Bučinskas, Rimantas Subačius
Abstract: Early defect detection and monitoring of rope systems constitute important safety requirements for equipment that employs ropes as single driving component, e.g. lifts, rope trains, etc. Quality characteristics of ropes are regulated by procedures of safety standards and are prescribed in safety standards of transportation machines, which are particularly stringent in the case of human elevating equipment. Many types of rope quality control are applied in practice but standard control procedure of such nonhomogeneous structures as ropes with electromagnetic methods are still not fully reliable, particularly in the case of broken wires in rope strands. The paper presents a method for detection of the aforementioned rope defects using dynamic properties of a rope that is treated as a dynamic system. The proposed method enables to measure dynamic characteristics of a rope system and, based on obtained results, evaluate rope quality, determine the presence of broken strands and define cross-section of the defects. Analysis of dynamic properties is used in order to establish existence of a defect. Aim of such analysis is to determine some characteristic natural frequencies corresponding to broken strand and change of the lowest natural frequencies that represent the rope as a constrained system. The paper also addresses the issues of equipment and methodology required for defect detection in ropes together with the necessary conditions. Final conclusions are formulated with regard to possibility of implementing the proposed method in real working conditions.
Authors: Ryszard Jasiński
Abstract: During start-up of hydrotronic system (hydraulic system with electric control) in low ambient temperatures a faulty operation may occur. The principles and conditions of safe operation of hydraulically (hydrotronically) driven machines and devices is essential for their designers and operators. For these reasons the author did a series of tests of hydraulic (hydrotronic) components and systems under thermal shock conditions (cooled-down components were supplied with hot working medium). In such conditions starting parameters of the selected hydrotronic components and systems, which secured safety of their operation, were determined. During start-up of a hydrotronic system under thermal shock conditions elements of hydraulic components warm up in a non-uniform way, due to varying material and shape properties. This causes change of clearances between the cooperating elements and may lead to faulty performance of hydraulic components and result in machine break-down. Heat transfer coefficients between oil and swilled element were determined and used for a calculation method developed by the author. The method enables to predict correct or incorrect operation of hydrotronic system.
Authors: Alexandra I. Khalyasmaa, Stepan A. Dmitriev, Sergey E. Kokin, Daniil A. Glushkov, Pavel Kuzin
Abstract: This paper addresses the problems, connected with implementation of 110-220 kV power transformer structural model for automated equipment functional state assessment system based on test and technical diagnostics data. This article describes the basic construction principles of hybrid neural network using Takagi-Sugeno fuzzy method. The paper also provides the statistical data analysis results for power transformers (of real energy grid part) to define fuzzy neural network criteria (layers).
Authors: Zbigniew Stanik
Abstract: An increasing number of bearings in the components and units of the mechanical systems for motor vehicles is one of the many effects of the rapid growth of their technical and design advancement. Due to the nature of their responsibility, it's necessary to diagnose. The article describes the currently used methods of diagnosis workshop practice of bearings and presents own proposals based on vibroacoustic diagnostic methods.
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