scholarly journals Diagnosis and Model Based Identification of a Coupling Misalignment

2005 ◽  
Vol 12 (4) ◽  
pp. 293-308 ◽  
Author(s):  
P. Pennacchi ◽  
A. Vania
Keyword(s):  
Shape Analysis ◽  
Diagnostic Techniques ◽  
Rotating Machinery ◽  
Small Power ◽  
Diagnostic Strategies ◽  
Rotating Speed ◽  
Model Based ◽  
Fault Type ◽  
First Case

This paper is focused on the application of two different diagnostic techniques aimed to identify the most important faults in rotating machinery as well as on the simulation and prediction of the frequency response of rotating machines. The application of the two diagnostics techniques, the orbit shape analysis and the model based identification in the frequency domain, is described by means of an experimental case study that concerns a gas turbine-generator unit of a small power plant whose rotor-train was affected by an angular misalignment in a flexible coupling, caused by a wrong machine assembling. The fault type is identified by means of the orbit shape analysis, then the equivalent bending moments, which enable the shaft experimental vibrations to be simulated, have been identified using a model based identification method. These excitations have been used to predict the machine vibrations in a large rotating speed range inside which no monitoring data were available. To the best of the authors' knowledge, this is the first case of identification of coupling misalignment and prediction of the consequent machine behaviour in an actual size rotating machinery. The successful results obtained emphasise the usefulness of integrating common condition monitoring techniques with diagnostic strategies.

scholarly journals Identification of Rub and Unbalance in 320 MW Turbogenerators

2003 ◽  
Vol 9 (2) ◽  
pp. 97-112 ◽  
Author(s):  
N. Bachschmid ◽  
P. Pennacchi ◽  
A. Vania ◽  
G. A. Zanetta ◽  
L. Gregori
Keyword(s):  
Power Plant ◽  
Frequency Domain ◽  
Theoretical Background ◽  
Fault Identification ◽  
Vibration Measurements ◽  
Rotating Speed ◽  
Model Based ◽  
First Case ◽  
Identification Technique ◽  
Fossil Power Plant

This article presents two experiences of applying a model-based fault-identification method to real machines. The first case presented is an unbalance identification in a 320 MW turbogenerator unit operating in a fossil power plant. In the second case, concerning a machine of the same size but from a different manufacturer, the turbine has been affected by a rub in the sealings. This time, the fault is modeled by local bows. The identification of the faults is performed by means of a model-based identification technique in a frequency domain, suitably modified in order to take into account simultaneous faults. The theoretical background of the applied method is briefly illustrated and some considerations are also presented about the best choice of the rotating speed set of the run-down transient to be used for an effective identification and about the appropriate weighting of vibration measurements at the machine bearings.

scholarly journals Identification of Rub and Unbalance in 320-MW Turbogenerators

2004 ◽  
Vol 10 (4) ◽  
pp. 265-281 ◽  
Author(s):  
N. Bachschmid ◽  
P. Pennacchi ◽  
A. Vania ◽  
G. A. Zanetta ◽  
L. Gregori
Keyword(s):  
Power Plant ◽  
Frequency Domain ◽  
Theoretical Background ◽  
Fault Identification ◽  
Rotating Speed ◽  
Model Based ◽  
First Case ◽  
Identification Technique ◽  
Lp Turbine ◽  
Fossil Power Plant

This article presents two experiences of application of a model-based fault identification method on real machines. The first case presented is an unbalance identification on a 320-MW turbogenerator unit operating in a fossil power plant. In the second case, concerning a machine of the same size but of a different manufacturer, the Low Pressure (LP) turbine was affected by a rub in the sealings and this time, the fault was modeled by local bows. The identification of the faults is performed by means of a model-based identification technique in frequency domain, suitably modified in order to take into account simultaneous faults. The theoretical background of the applied method is briefly illustrated and some considerations also are presented about the best choice of the rotating speed set of the run-down transient to be used for an effective identification and about the appropriate weighting of vibration measurements at the machine bearings.

scholarly journals Faults Identification and Corrective Actions in Rotating Machinery at Rated Speed

2006 ◽  
Vol 13 (4-5) ◽  
pp. 485-503 ◽  
Author(s):  
Nicolò Bachschmid ◽  
Paolo Pennacchi
Keyword(s):  
Frequency Domain ◽  
Rotating Machinery ◽  
Fault Identification ◽  
Operating Speed ◽  
Huge Amount ◽  
Rotor Systems ◽  
Rotating Speed ◽  
Normal Operating ◽  
Vibration Data ◽  
Model Based

Malfunction identification in rotor systems by means of a model based approach in the frequency domain during long lasting speed transients (coast-down procedures in large turbo-generators), where a huge amount of vibration data at different rotating speeds is usually collected, has proved to be very effective. This paper explores the possibility to adapt this method to the situation when the vibration data are available at one rotating speed only, which in real machines is generally the normal operating speed. It results that single speed fault identification can be successful, but does not allow to discriminate between different malfunctions that generate similar symptoms. Neverthless the identification results can be used to define corrective balancing masses.

Impairment Tutorial: Neurological Impairment Evaluation: Overview of Sixth Edition Approaches

2008 ◽  
Vol 13 (2) ◽  
pp. 6-8
Author(s):  
Lorne Direnfeld ◽  
Christopher R. Brigham ◽  
Elizabeth Genovese
Keyword(s):  
Spinal Cord ◽  
Neurological Impairment ◽  
Diagnostic Techniques ◽  
Neurological Deficits ◽  
Sixth Edition ◽  
Pain Disability ◽  
Whole Person ◽  
Disability Questionnaire ◽  
Cervical Plating

Abstract The AMA Guides to the Evaluation of Permanent Impairment (AMA Guides), does not provide a Diagnosis-based estimate of impairment due to syringomyelia, a disorder in which a cyst (syrinx), develops within the central spinal cord and destroys neural tissue as it expands. The AMA Guides, however, does provide an approach to rating a syringomyelia based on objective findings of neurological deficits identified during a neurological examination and demonstrated by standard diagnostic techniques. Syringomelia may occur after spinal cord trauma, including a contusion of the cord. A case study illustrates the rating process: The case patient is a 46-year-old male who fell backwards, landing on his upper back and head; over a five-year period he received a T5-6 laminectomy and later partial corpectomies of C5, C6, and C7, cervical discectomy C5-6 and C6-7; iliac crest strut graft fusion of C5-6 and C6-7; and anterior cervical plating of C5 to C7 for treatment of myelopathy; postoperatively, the patient developed dysphagia. The evaluating physician should determine which conditions are ratable, rate each of these components, and combine the resulting whole person impairments without omission or duplication of a ratable impairment. The article includes a pain disability questionnaire that can be used in conjunction with evaluations conducted according to Chapter 3, Pain, and Chapter 17, The Spine.

Scales and Units

2018 ◽  
Author(s):  
Kathryn M. de Luna
Keyword(s):  
Language Change ◽  
Historical Linguistics ◽  
Bantu Languages ◽  
The North ◽  
First Case ◽  
Linguistic Evidence ◽  
River Region ◽  
History Of ◽  
Alternative Approaches

This chapter uses two case studies to explore how historians study language movement and change through comparative historical linguistics. The first case study stands as a short chapter in the larger history of the expansion of Bantu languages across eastern, central, and southern Africa. It focuses on the expansion of proto-Kafue, ca. 950–1250, from a linguistic homeland in the middle Kafue River region to lands beyond the Lukanga swamps to the north and the Zambezi River to the south. This expansion was made possible by a dramatic reconfiguration of ties of kinship. The second case study explores linguistic evidence for ridicule along the Lozi-Botatwe frontier in the mid- to late 19th century. Significantly, the units and scales of language movement and change in precolonial periods rendered visible through comparative historical linguistics bring to our attention alternative approaches to language change and movement in contemporary Africa.

Applications of random graphs

2017 ◽  
Author(s):  
A.C.C. Coolen ◽  
A. Annibale ◽  
E.S. Roberts
Keyword(s):  
Social Networks ◽  
Random Graphs ◽  
Interaction Network ◽  
Power Grids ◽  
Protein Protein Interaction ◽  
Topological Features ◽  
First Case ◽  
The Stability ◽  
Protein Protein Interaction Network

This chapter reviews graph generation techniques in the context of applications. The first case study is power grids, where proposed strategies to prevent blackouts have been tested on tailored random graphs. The second case study is in social networks. Applications of random graphs to social networks are extremely wide ranging – the particular aspect looked at here is modelling the spread of disease on a social network – and how a particular construction based on projecting from a bipartite graph successfully captures some of the clustering observed in real social networks. The third case study is on null models of food webs, discussing the specific constraints relevant to this application, and the topological features which may contribute to the stability of an ecosystem. The final case study is taken from molecular biology, discussing the importance of unbiased graph sampling when considering if motifs are over-represented in a protein–protein interaction network.

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