345 research outputs found
Wear debris: basic features and machine health diagnostics
Modern high speed and power machinery components like gears, bearings, pumps, hydraulics and
motors normally suffer from wear phenomena during operation. The study of wear debris can help
estimate the condition of the surface of a component, so its basic features may be used to diagnose
component health prior to failure. In this paper, a review is presented of the current literature related to
wear debris and its analysis. The basic features of wear debris are highlighted, and their possible
potential to diagnose the health of machine components is discussed. The basic features of wear debris
have been classified with respect to the approach of measurement for component health diagnostics. In
addition, each feature has been detailed with its possible measurement descriptors, its trend during
machine component operation, and its distinct health diagnostics capability. Finally the paper proposes
advances in machine component health diagnostics solution, by optimising the diagnostic capabilities
of basic wear debris features
Condition monitoring and fault detection of inverter-fed rotating machinery
Condition monitoring of rotating machinery is crucial in industry. It can prevent long term outages that can prove costly, prevent injury to machine operators, and lower product quality. Induction motors, often described as the workhorse of industry, are popular in industry because of their robustness, efficiency and the need for low maintenance. They are, however, prone to faults when used improperly or under strenuous conditions. Gearboxes are also an important component in industry, used to transmit motion and force by means of successively engaging teeth. They too are prone to damage and can disrupt industrial processes if failure is unplanned for. Reciprocating compressors are widely used in the petroleum and the petrochemical industry. Their complex structure, and operation under poor conditions makes them prone to faults, making condition monitoring necessary to prevent accidents, and for maintenance decision-making and cost minimization. Various techniques have been extensively investigated and found to be reliable tools for the identification of faults in these machines. This thesis, however, sets out to establish a single non-invasive tool that can be used to identify the faults on all these machines. Literature on condition monitoring of induction motors, gearboxes, and reciprocating compressors is extensively reviewed. The time, frequency, and time-frequency domain techniques that are used in this thesis are also discussed. Statistical indicators were used in the time domain, the Fourier Transform in the frequency domain, and Wavelet Transforms in the time-frequency domain. Vibration and current, which are two of the most popular parameters for fault detection, were considered. The test rig equipment that is used to carry to the experiments, which comprised a modified Machine Fault Simulator -Magnum (MFS-MG), is presented and discussed. The fault detection strategies rely on the presence of a fault signature. The test rig that was used allows for the simulation of individual or multiple concurrent faults to the test machinery. The experiments were carried out under steady-state and transient conditions with the faults in the machines isolated, and then with multiple faults implemented concurrently. The results of the fault detection strategies are analysed, and conclusions are drawn based on the performances of these tools in the detection of the faults in the machinery
Bearing fault diagnosis method based on Hilbert envelope spectrum and deep belief network
When fault occurs in bearing, the frequency spectrum of vibration signal would change and it contains a considerable amount of fault information which can reflect the actual work condition and the fault type of bearing. Recently, the statistical features of the frequency spectrum have been widely used in bearing fault diagnosis. However, there are lots of statistical features with different sensitivity to fault identification. Selecting the most sensible statistical features for improving classification accuracy is often determined with experience, which will make great subjective influence on the fault diagnosis results. Deep belief network (DBN) is a deep neural network which can automatically find a latent hierarchical feature representation from the high dimension input data. In this study, a bearing fault diagnosis method based on Hilbert envelope spectrum and DBN is proposed. Firstly, the vibration signals under different test conditions are resampled. Secondly, the whole Hilbert envelope spectrum of the resampled signal is used directly as eigenvector to characterize the fault type of bearing. Finally, a DBN classifier model is established to recognize the fault type of bearing. DBN classifier model can be used as both an automatic feature extractor and a classifier for bearing fault diagnosis. Therefore, the process of fault diagnosis can be greatly simplified. The results of two different experiments demonstrate that the proposed method outperforms the competing methods and it can obtain a more excellent diagnostic performance
Finland-India Business Prospects 2007-2017
Finland-India Economic Relations were researched for the first time in a study that analysed mutual trade and investment potential through the lens of revealed comparative advantage and identified profitably tradable goods at 4-digit and 8-digit disaggregated levels in the standard international trade classification (Mathur, 1998). This study was made freely available on the world wide web for five years through http:// www.uta.fi/kati as part of longitudinal action research to study how small and large players would take advantage of this freebie. This paper provides initial results of a sequel study initiated in 2005 to understand what happened thereafter, whether trade grew, and to analyse how trade could diversify from identification of new opportunities for product-services linkages after the expiry of the transitional period that brought GATS into effect in 2005. Finlands share in Indian imports and exports has grown rapidly and exponentially and the prospects are vast but the potential realised by 2007 remains considerably untapped and far below comparable figures for other EU countries. This study emphasises the need for policy research on institutional barriers to design new gateways beyond an increased frequency of contact between people from the two countries. The conclusion that robust bridges could be built through tripartite fora comprising business, government and academia points to the need for new institutionalities and deepening research studies, some of which initiated as part of the Finland-India Economic Relations project, are at various stages of progress and expected to be completed during 2007-2010.
Design and development of auxiliary components for a new two-stroke, stratified-charge, lean-burn gasoline engine
A unique stepped-piston engine was developed by a group of research engineers at Universiti Teknologi Malaysia (UTM), from 2003 to 2005. The development work undertaken by them engulfs design, prototyping and evaluation over a predetermined period of time which was iterative and challenging in nature. The main objective of the program is to demonstrate local R&D capabilities on small engine work that is able to produce mobile powerhouse of comparable output, having low-fuel consumption and acceptable emission than its crankcase counterpart of similar displacement. A two-stroke engine work was selected as it posses a number of technological challenges, increase in its thermal efficiency, which upon successful undertakings will be useful in assisting the group in future powertrain undertakings in UTM. In its carbureted version, the single-cylinder aircooled engine incorporates a three-port transfer system and a dedicated crankcase breather. These features will enable the prototype to have high induction efficiency and to behave very much a two-stroke engine but equipped with a four-stroke crankcase lubrication system. After a series of analytical work the engine was subjected to a series of laboratory trials. It was also tested on a small watercraft platform with promising indication of its flexibility of use as a prime mover in mobile platform. In an effort to further enhance its technology features, the researchers have also embarked on the development of an add-on auxiliary system. The system comprises of an engine control unit (ECU), a directinjector unit, a dedicated lubricant dispenser unit and an embedded common rail fuel unit. This support system was incorporated onto the engine to demonstrate the finer points of environmental-friendly and fuel economy features. The outcome of this complete package is described in the report, covering the methodology and the final characteristics of the mobile power plant
The potential role of new technology for enhanced safety and performance of nuclear power plants through improved service maintenance
Refinements in the safety and performance of nuclear power plants must be made to maintain public confidence and ensure competitiveness with other power sources. The aircraft industry, US Navy, and other programs have proven many advanced service maintenance methods that may improve commercial nuclear plants. This thesis is concerned with how new technologies in sensing and monitoring can be used to reduce the potential for hardware failures. The specific components with the greatest impacts upon safety and performance were determined using historical data from the experience of the nuclear industry. Failure modes associated with selected components are used to indicate the most important monitoring needs and these requirements help focus a technology survey for potential improvements. The thesis concludes with a discussion of possible applications which may enhance monitoring needs. Proposals for focusing future research to further develop appropriate technologies are presented. Nuclear facility managers are provided a means to self-analyze the status of onsite efforts to improve vital safety and performance related equipment in this thesis. Many of the monitoring needs and potential improvements indicated have general application to most plants. The process discussed in this report can be used to further tailor technology to plant specific needs
Establishment of a novel predictive reliability assessment strategy for ship machinery
There is no doubt that recent years, maritime industry is moving forward to novel and sophisticated inspection and maintenance practices. Nowadays maintenance is encountered as an operational method, which can be employed both as a profit generating process and a cost reduction budget centre through an enhanced Operation and Maintenance (O&M) strategy. In the first place, a flexible framework to be applicable on complex system level of machinery can be introduced towards ship maintenance scheduling of systems, subsystems and components.;This holistic inspection and maintenance notion should be implemented by integrating different strategies, methodologies, technologies and tools, suitably selected by fulfilling the requirements of the selected ship systems. In this thesis, an innovative maintenance strategy for ship machinery is proposed, namely the Probabilistic Machinery Reliability Assessment (PMRA) strategy focusing towards the reliability and safety enhancement of main systems, subsystems and maintainable units and components.;In this respect, the combination of a data mining method (k-means), the manufacturer safety aspects, the dynamic state modelling (Markov Chains), the probabilistic predictive reliability assessment (Bayesian Belief Networks) and the qualitative decision making (Failure Modes and Effects Analysis) is employed encompassing the benefits of qualitative and quantitative reliability assessment. PMRA has been clearly demonstrated in two case studies applied on offshore platform oil and gas and selected ship machinery.;The results are used to identify the most unreliability systems, subsystems and components, while advising suitable practical inspection and maintenance activities. The proposed PMRA strategy is also tested in a flexible sensitivity analysis scheme.There is no doubt that recent years, maritime industry is moving forward to novel and sophisticated inspection and maintenance practices. Nowadays maintenance is encountered as an operational method, which can be employed both as a profit generating process and a cost reduction budget centre through an enhanced Operation and Maintenance (O&M) strategy. In the first place, a flexible framework to be applicable on complex system level of machinery can be introduced towards ship maintenance scheduling of systems, subsystems and components.;This holistic inspection and maintenance notion should be implemented by integrating different strategies, methodologies, technologies and tools, suitably selected by fulfilling the requirements of the selected ship systems. In this thesis, an innovative maintenance strategy for ship machinery is proposed, namely the Probabilistic Machinery Reliability Assessment (PMRA) strategy focusing towards the reliability and safety enhancement of main systems, subsystems and maintainable units and components.;In this respect, the combination of a data mining method (k-means), the manufacturer safety aspects, the dynamic state modelling (Markov Chains), the probabilistic predictive reliability assessment (Bayesian Belief Networks) and the qualitative decision making (Failure Modes and Effects Analysis) is employed encompassing the benefits of qualitative and quantitative reliability assessment. PMRA has been clearly demonstrated in two case studies applied on offshore platform oil and gas and selected ship machinery.;The results are used to identify the most unreliability systems, subsystems and components, while advising suitable practical inspection and maintenance activities. The proposed PMRA strategy is also tested in a flexible sensitivity analysis scheme
A Finite Element Investigation of Existing Pipework Vibration Acceptance Criteria
In this thesis, a literature review was conducted to cover the assessment techniques for Oil and Gas (O&G) pipework that includes Small Bore Pipes (SBP). The various methods that were studied are the most commonly found in the field today. The advantages and disadvantages were analyzed. Multiple studies performed for the SBP connection which is the most susceptible area for fatigue failure (where it is usually welded on).
A robust Finite Element Analysis was carried out that initially analyzed the variations to the maximum stress, SBP tip velocity, and the first mode by changing the geometry of the system including the length and schedule of pipes.
Finally, a sample system was designed, and hundreds of results were gathered from the FEA models which were fed to multiple machine learning programs that trained them. To evaluate the accuracy of the programs, a sample systemâs geometrical parameters were inputted, the first mode frequency was predicted, and the percentage error was calculated. The output of this research would help inspectors to determine the systemâs first natural frequency easily and thus expedite the fatigue risk assessment using existing vibration guidelines such as ASME
Volume 3 â Conference
We are pleased to present the conference proceedings for the 12th edition of the International Fluid Power Conference (IFK). The IFK is one of the worldâs most significant scientific conferences on fluid power control technology and systems. It offers a common platform for the presentation and discussion of trends and innovations to manufacturers, users and scientists. The Chair of Fluid-Mechatronic Systems at the TU Dresden is organizing and hosting the IFK for the sixth time. Supporting hosts are the Fluid Power Association of the German Engineering Federation (VDMA), Dresdner Verein zur Förderung der Fluidtechnik e. V. (DVF) and GWT-TUD GmbH. The organization and the conference location alternates every two years between the Chair of Fluid-Mechatronic Systems in Dresden and the Institute for Fluid Power Drives and Systems in Aachen. The symposium on the first day is dedicated to presentations focused on methodology and fundamental research. The two following conference days offer a wide variety of application and technology orientated papers about the latest state of the art in fluid power. It is this combination that makes the IFK a unique and excellent forum for the exchange of academic research and industrial application experience. A simultaneously ongoing exhibition offers the possibility to get product information and to have individual talks with manufacturers. The theme of the 12th IFK is âFluid Power â Future Technologyâ, covering topics that enable the development of 5G-ready, cost-efficient and demand-driven structures, as well as individual decentralized drives. Another topic is the real-time data exchange that allows the application of numerous predictive maintenance strategies, which will significantly increase the availability of fluid power systems and their elements and ensure their improved lifetime performance. We create an atmosphere for casual exchange by offering a vast frame and cultural program. This includes a get-together, a conference banquet, laboratory festivities and some physical activities such as jogging in Dresdenâs old town.:Group 8: Pneumatics
Group 9 | 11: Mobile applications
Group 10: Special domains
Group 12: Novel system architectures
Group 13 | 15: Actuators & sensors
Group 14: Safety & reliabilit
Aeronautical engineering: A continuing bibliography with indexes (supplement 317)
This bibliography lists 224 reports, articles, and other documents introduced into the NASA scientific and technical information system in May 1995. Subject coverage includes: design, construction and testing of aircraft and aircraft engines; aircraft components, equipment, and systems; ground support systems; and theoretical and applied aspects of aerodynamics and general fluid dynamics
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