Determining the root cause of a neighbouring-cell-interaction-induced latch-up failure event

2016 ◽  
Author(s):  
H. W. Ho ◽  
Wendy W. Y. Lau ◽  
S. H. Goh ◽  
B. L. Yeoh ◽  
M. Seungje ◽  
...  
Keyword(s):  
Cell Interaction ◽  
Neighbouring Cell ◽  
Root Cause ◽  
Failure Event ◽  
Latch Up

Aeroderivative Gas Turbine Coupling Generator Redesign

2013 ◽  
Author(s):  
Alejandro Hernández Rossette ◽  
Rafael García Illescas ◽  
Zdzislaw Mazur
Keyword(s):  
Gas Turbines ◽  
Longitudinal Direction ◽  
Rehabilitation Process ◽  
Root Cause ◽  
Dynamic Forces ◽  
Failure Event ◽  
Couple Analysis ◽  
Original Configuration ◽  
Total Fracture

A major failure event was experienced at a 44 MW plant powered by four aeroderivative gas turbines arranged in two units, property of the Federal Commission of Electricity (CFE). The failure consisted of total fracture in the shaft coupling between the generator and free-turbine. Unit 2 has a twin pack configuration with two aero derivative Pratt&Whitney 20 MW gas turbines coupled to one generator at both end sides. The “A” side generator coupling was completely damaged as well as the coupling configuration at the free turbine. Failure analysis showed as root cause, an abnormal configuration of the coupling systems between the free turbine to rotor generator at side “A”. This side had an additional shaft component to compensate a longer coupling distance between the turbine and generator. This was longer than the original distance, generating additional dynamic forces during operation leading to a fatigue failure mechanism. The replacement coupling configuration for the rotor generator was different than the Original Equipment Manufacturer (OEM). The new (non-OEM) spare rotor generator was shorter in the longitudinal direction than the original one, forcing the addition of a new shaft in one side of the generator. This work describes the rehabilitation process of the generator coupling by the replacement of the old configuration by a new redesigned coupling. This was done keeping the original configuration distances and components for both end shaft sides of the rotor generator. The paper includes the redesigned couple analysis by finite element method and the in-situ activities for the installation of the new couple in the rotor generator.

Latch-Up Root Cause Analysis for New ASIC Design

2007 ◽  
Author(s):  
W. Danielak ◽  
W. Machado ◽  
M. Jaffer ◽  
S. Waldstein ◽  
A. Jordan ◽  
...  
Keyword(s):  
Integrated Circuit ◽  
Supply Voltage ◽  
Root Cause Analysis ◽  
Detailed Calculation ◽  
Cause Analysis ◽  
Asic Design ◽  
Root Cause ◽  
Application Specific Integrated Circuit ◽  
Application Specific ◽  
Latch Up

Abstract The analyzed new Application Specific Integrated Circuit (ASIC) design failed latch-up test on two input pins during current stress. In order to determine the root cause, the Failure Analysis (FA) with use of backside Emission Microscopy (EMMI) was performed. The EMMI results were followed by detailed layout and circuit analysis. It was found that the root cause of the latch-up is an abutment of two specific cells (called “cell C” and “cell D”), where the N-well was grounded creating a parasitic NPN transistor sustaining the latch-up. A detailed calculation of parasitic interconnection resistances from the layout revealed some differences between latching and non-latching pins. The analytical model to explain the latch-up behavior based on parasitic resistances was applied successfully to root cause analysis. Summarizing, the latch–up behavior can be explained by the abutment of cells C and D, parasitic interconnect resistances and cell location with respect to the substrate bumps. In conclusions the following recommendations were made: 1. Remove the n-well in cell D; 2. Connect specific cells (B and D) to higher supply voltage; 3. Implement p+ guard rings for cells C and D; 4. Optimize placement of ground bumps; 5. Eliminate abutment of cell C and D.

Design Flaw Enhanced by Improper Workmanship to Cause Fatigue Failure on Rotor Blade of Compressor Gas Turbine

2014 ◽  
Vol 660 ◽  
pp. 593-597
Author(s):  
Slameto Wiryolukito
Keyword(s):  
Gas Turbine ◽  
Fatigue Failure ◽  
Root Surface ◽  
Rotor Blades ◽  
Blade Surface ◽  
Compressor Blades ◽  
Root Cause ◽  
Root Area ◽  
Failure Event ◽  
Cause Of Failure

Ten stages of Compressor Engine S/N 123 of X-Gas Turbine failed in service prior the schedule for overhaul at 40,000 hour. At the failure event the running hour was 29,600. The maintenance was normally done every 8000 hours including filter and gasket replacement, instrument re-calibration, and bore scope examination. Upon dismantling, it was found one blade at rotor stage #3 failed with facture surface strongly indicated a fatigue failure, defective on stator and rotor blades at downstream, no defective blades at upstream. Detail examination confirm Root Cause of failure on Compressor Blade of X-Gas Turbine were combination of a sharp radius of root chamfer as the major contributor and at lesser extent enhanced by “scratches” exist on root blade free surface. There was no evidences Foreign Objects or corrosion contributed to fail the compressor blades. Blade material was sound and did not contribute to fail the blade. The recommendations to avoid failure reoccurrences were all existing installed rotor blades shall be dismantled and examined for the existence of crack at their root area. Inspection on brand new blades for the existence of scratches on blade surface prior assembly shall be strongly imposed; blade with preexisting scratch shall be rejected. In a design stages, increase the sharp chamfer radius on blade root is worth-while to be analyzed further. Workmanship during blade assembly shall not develop any scratch on blade surface especially on its root surface. A procedure and schedule for inspection on the running blades shall be refined to be able to detect any crack on the operating blades; special attention shall be given on root area.

scholarly journals Analysis of the Clinical Education Situation framework: a tool for identifying the root cause of student failure in the United States

2019 ◽  
Vol 16 ◽  
pp. 11
Author(s):  
Katherine Myers ◽  
Kyle Covington
Keyword(s):  
Clinical Education ◽  
Root Cause Analysis ◽  
The United States ◽  
Primary Role ◽  
Cause Analysis ◽  
Academic Environments ◽  
Doctor Of Physical Therapy ◽  
Root Cause ◽  
Student Failure ◽  
Failure Event

Doctor of physical therapy preparation requires extensive time in precepted clinical education, which involves multiple stakeholders. Student outcomes in clinical education are impacted by many factors, and, in the case of failure, it can be challenging to determine which factors played a primary role in the poor result. Using existing root-cause analysis processes, the authors developed and implemented a framework designed to identify the causes of student failure in clinical education. This framework, when applied to a specific student failure event, can be used to identify the factors that contributed to the situation and to reveal opportunities for improvement in both the clinical and academic environments. A root-cause analysis framework can help to drive change at the programmatic level, and future studies should focus on the framework’s application to a variety of clinical and didactic settings.

Bacteriophages Associated with Turkey Coecums in Bluecomb-Infected and Healthy Birds

1969 ◽  
Vol 27 ◽  
pp. 226-227
Author(s):  
A. E. Ritchie
Keyword(s):  
Host Cell ◽  
Causal Relationship ◽  
Cell Cultures ◽  
Cell Interaction ◽  
Etiologic Agent ◽  
Viral Origin ◽  
Intestinal Contents ◽  
Host Cell Interaction

The cause of bluecomb disease in turkeys is unknown. Filtration of infective intestinal contents suggests a viral origin. To date, it has not been possible to isolate the etiologic agent in various cell cultures. The purpose of this work was to characterize as many virus-like entities as were recognizable in intestines of both healthy and bluecomb-infected turkeys. By a comparison of the viral populations it was hoped that some insight might be gained into the cause of this disease. Studies of turkey hemorraghic enteritis by Gross and Moore (Avian Dis. 11: 296-307, 1967) have suggested that a bacteriophage-host cell interaction may bear some causal relationship to that disease.

Application Of Electron Microscopy To Automotive Finish Defect Analysis

1990 ◽  
Vol 48 (2) ◽  
pp. 258-259
Author(s):  
Martin J. Mahon ◽  
Patrick W. Keating ◽  
John T. McLaughlin
Keyword(s):  
Electron Microscopy ◽  
Zero Tolerance ◽  
Polymeric Materials ◽  
Plant Management ◽  
Defect Analysis ◽  
X Ray ◽  
Root Cause ◽  
Cutting Out ◽  
Foreign Materials ◽  
Automotive Finish

Coatings are applied to appliances, instruments and automobiles for a variety of reasons including corrosion protection and enhancement of market value. Automobile finishes are a highly complex blend of polymeric materials which have a definite impact on the eventual ability of a car to sell. Consumers report that the gloss of the finish is one of the major items they look for in an automobile.With the finish being such an important part of the automobile, there is a zero tolerance for paint defects by auto assembly plant management. Owing to the increased complexity of the paint matrix and its inability to be “forgiving” when foreign materials are introduced into a newly applied finish, the analysis of paint defects has taken on unparalleled importance. Scanning electron microscopy with its attendant x-ray analysis capability is the premier method of examining defects and attempting to identify their root cause.Defects are normally examined by cutting out a coupon sized portion of the autobody and viewing in an SEM at various angles.

Root Cause Analyses of Suicides of Mental Health Clients

Crisis ◽  
2015 ◽  
Vol 36 (5) ◽  
pp. 316-324 ◽  
Author(s):  
Donna Gillies ◽  
David Chicop ◽  
Paul O'Halloran
Keyword(s):  
Mental Health ◽  
Suicide Prevention ◽  
Common Factor ◽  
Data Collection Tool ◽  
Related Factors ◽  
Root Cause ◽  
Communication Problems ◽  
The Individual ◽  
Mental Health Clients ◽  
Imminent Risk

Abstract. Background: The ability to predict imminent risk of suicide is limited, particularly among mental health clients. Root cause analysis (RCA) can be used by health services to identify service-wide approaches to suicide prevention. Aims: To (a) develop a standardized taxonomy for RCAs; (b) to quantitate service-related factors associated with suicides; and (c) to identify service-related suicide prevention strategies. Method: The RCAs of all people who died by suicide within 1 week of contact with the mental health service over 5 years were thematically analyzed using a data collection tool. Results: Data were derived from RCAs of all 64 people who died by suicide between 2008 and 2012. Major themes were categorized as individual, situational, and care-related factors. The most common factor was that clients had recently denied suicidality. Reliance on carers, recent changes in medication, communication problems, and problems in follow-through were also commonly identified. Conclusion: Given the difficulty in predicting suicide in people whose expressions of suicidal ideation change so rapidly, services may consider the use of strategies aimed at improving the individual, stressor, support, and care factors identified in this study.

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