Rub Diagnostics Based on Vibration Data

2013 ◽  
Author(s):  
John J. Yu
Keyword(s):  
Steady State ◽  
Case Studies ◽  
Diagnostic Tools ◽  
Transient Conditions ◽  
Vibration Data ◽  
Root Cause

Vibration excursion in turbomachinery is troublesome, especially when approaching or exceeding a trip level. Understanding of its root-cause is extremely crucial for taking appropriate actions and resolving the issue. Rubs are certainly among the most common malfunctions that cause vibration excursion. This paper discusses how to diagnose rubs that typically occur in turbomachinery based on vibration data. These include rubs occurring in both steady-state and transient conditions. Selection and interpretation of vibration data plots such as trend, polar, Bode, orbit, and waterfall are illustrated that pinpoint rubbing and resulted shaft bow symptoms. All data presented have been obtained from real machines where rubs occurred. Mainly case studies are presented in this paper. The presented cases and concluded diagnostic rules using vibration data plots will help practicing engineers as well as enhance diagnostic tools.

Interpreting Laser-Based Fault Localization Results: Case Studies

2019 ◽  
Author(s):  
Sukho Lee ◽  
John van den Biggelaar ◽  
Marc van Veenhuizen
Keyword(s):  
Case Studies ◽  
Circuit Design ◽  
High Sensitivity ◽  
Failure Behavior ◽  
Process Technology ◽  
Resistance Change ◽  
Voltage Imaging ◽  
Root Cause ◽  
First Case ◽  
Proper Interpretation

Abstract Laser-based dynamic analysis has become a very important tool for analyzing advanced process technology and complex circuit design. Thus, many good reference papers discuss high resolution, high sensitivity, and useful applications. However, proper interpretation of the measurement is important as well to understand the failure behavior and find the root cause. This paper demonstrates this importance by describing two insightful case studies with unique observations from laser voltage imaging/laser voltage probing (LVP), optical beam induced resistance change, and soft defect localization (SDL) analysis, which required an in-depth interpretation of the failure analysis (FA) results. The first case is a sawtooth LVP signal induced by a metal short. The second case, a mismatched result between an LVP and SDL analysis, is a good case of unusual LVP data induced by a very sensitive response to laser light. The two cases provide a good reference on how to properly explain FA results.

Contamination Troubleshooting Approach from Problem to Solution

2019 ◽  
Author(s):  
Victor K. F. Chia ◽  
Hugh E. Gotts ◽  
Fuhe Li ◽  
Mark Camenzind
Keyword(s):  
Case Studies ◽  
Semiconductor Devices ◽  
Analytical Techniques ◽  
General Knowledge ◽  
Contamination Source ◽  
Root Cause ◽  
Sources Of Contamination

Abstract Semiconductor devices are sensitive to contamination that can cause product defects and product rejects. There are many possible types and sources of contamination. Root cause resolution of the contamination source can improve yield. The purpose of contamination troubleshooting is to identify and eliminate major yield limiters. This requires the use of a variety of analytical techniques[1]. Most important, it requires an understanding of the principle of contamination troubleshooting and general knowledge of analytical tests. This paper describes a contamination troubleshooting approach with case studies as examples of its application.

SEM-Based Nanoprobing on 40, 32 and 28 nm CMOS Devices Challenges for Semiconductor Failure Analysis

2013 ◽  
Author(s):  
Erik Paul ◽  
Holger Herzog ◽  
Sören Jansen ◽  
Christian Hobert ◽  
Eckhard Langer
Keyword(s):  
Electron Microscope ◽  
High Resolution ◽  
Scanning Electron Microscope ◽  
Failure Analysis ◽  
Case Studies ◽  
State Of The Art ◽  
Root Cause ◽  
Highly Efficient ◽  
Technology Nodes ◽  
Scanning Electron

Abstract This paper presents an effective device-level failure analysis (FA) method which uses a high-resolution low-kV Scanning Electron Microscope (SEM) in combination with an integrated state-of-the-art nanomanipulator to locate and characterize single defects in failing CMOS devices. The presented case studies utilize several FA-techniques in combination with SEM-based nanoprobing for nanometer node technologies and demonstrate how these methods are used to investigate the root cause of IC device failures. The methodology represents a highly-efficient physical failure analysis flow for 28nm and larger technology nodes.

scholarly journals Series Compensation of Transmission Systems: A Literature Survey

Energies ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1717
Author(s):  
Camilo Andrés Ordóñez ◽  
Antonio Gómez-Expósito ◽  
José María Maza-Ortega
Keyword(s):  
Steady State ◽  
Power Systems ◽  
Power System ◽  
Case Studies ◽  
Electronic Devices ◽  
Literature Survey ◽  
Power Electronic ◽  
Transmission Systems ◽  
Series Compensation ◽  
Near Future

This paper reviews the basics of series compensation in transmission systems through a literature survey. The benefits that this technology brings to enhance the steady state and dynamic operation of power systems are analyzed. The review outlines the evolution of the series compensation technologies, from mechanically operated switches to line- and self-commutated power electronic devices, covering control issues, different applications, practical realizations, and case studies. Finally, the paper closes with the major challenges that this technology will face in the near future to achieve a fully decarbonized power system.

scholarly journals Pressure Analysis in the Draft Tube of a Pump-Turbine under Steady and Transient Conditions

Energies ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 4732
Author(s):  
Jing Yang ◽  
Yue Lv ◽  
Dianhai Liu ◽  
Zhengwei Wang
Keyword(s):  
Steady State ◽  
Pressure Pulsation ◽  
Transient Flow ◽  
Draft Tube ◽  
Simulation Method ◽  
Wall Pressure ◽  
Pump Turbine ◽  
Steady State Condition ◽  
Transient Conditions ◽  
Pumped Storage

Pumped-storage power stations play a regulatory role in the power grid through frequent transition processes. The pressure pulsation in the draft tube of the pump-turbine under transient processes is important for safe operation, which is more intense than that in the steady-state condition. However, there is no effective method to obtain the exact pressure in the draft tube in the transient flow field. In this paper, the pressure in the draft tube of a pump-turbine under steady-state and transient conditions are studied by means of CFD. The reliability of the simulation method is verified by comparing the real pressure pulsation data with the test results. Due to the distribution of the pressure pulsation in the draft tube being complex and uneven, the location of the pressure monitoring points directly affects the accurate judgement of cavitation. Eight monitoring surfaces were set in the straight cone of the draft tube and nine monitoring points were set on each monitoring surface to analyze the pressure differences on the wall and inside the center of the draft tube. The relationships between the pressure pulsation value inside the center of the draft tube and on the wall are studied. The “critical” wall pressure pulsation value when cavitation occurs is obtained. This study provides references for judging cavitation occurrences by using the wall pressure pulsation value in practical engineering.

Thermal-Hydraulic Analysis of the 3-MW TRIGA MARK-II Research Reactor under Steady-State and Transient Conditions

2001 ◽  
Vol 135 (1) ◽  
pp. 51-66 ◽  
Author(s):  
M. Q. Huda ◽  
S. I. Bhuiyan ◽  
T. K. Chakrobortty ◽  
M. M. Sarker ◽  
M. A. W. Mondal
Keyword(s):  
Steady State ◽  
Research Reactor ◽  
Hydraulic Analysis ◽  
Transient Conditions ◽  
Triga Mark Ii ◽  
Thermal Hydraulic Analysis

scholarly journals Improving the FLORIS wind plant model for compatibility with gradient-based optimization

2017 ◽  
Vol 41 (5) ◽  
pp. 313-329 ◽  
Author(s):  
Jared J Thomas ◽  
Pieter MO Gebraad ◽  
Andrew Ning
Keyword(s):  
Steady State ◽  
Wind Turbine ◽  
Case Studies ◽  
Wind Farm ◽  
Optimization Problems ◽  
Algorithmic Differentiation ◽  
Function Calls ◽  
Gradient Based ◽  
Wake Model ◽  
Yaw Angle

The FLORIS (FLOw Redirection and Induction in Steady-state) model, a parametric wind turbine wake model that predicts steady-state wake characteristics based on wind turbine position and yaw angle, was developed for optimization of control settings and turbine locations. This article provides details on changes made to the FLORIS model to make the model more suitable for gradient-based optimization. Changes to the FLORIS model were made to remove discontinuities and add curvature to regions of non-physical zero gradient. Exact gradients for the FLORIS model were obtained using algorithmic differentiation. A set of three case studies demonstrate that using exact gradients with gradient-based optimization reduces the number of function calls by several orders of magnitude. The case studies also show that adding curvature improves convergence behavior, allowing gradient-based optimization algorithms used with the FLORIS model to more reliably find better solutions to wind farm optimization problems.

scholarly journals Harvesting subterranean clover seed – current practices, technology and issues

2021 ◽  
Vol 72 (3) ◽  
pp. 223
Author(s):  
Wesley M. Moss ◽  
Andrew L. Guzzomi ◽  
Kevin J. Foster ◽  
Megan H. Ryan ◽  
Phillip G. H. Nichols
Keyword(s):  
Soil Erosion ◽  
Case Studies ◽  
Seed Production ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Root Cause ◽  
Pasture Plant ◽  
Clover Seed ◽  
Production Industry ◽  
Pasture Legume

Subterranean clover (Trifolium subterraneum L.) is Australia’s most widely sown annual pasture legume. Its widespread use as a pasture plant requires a well-functioning seed production industry, and Australia is the only significant producer of subterranean clover seed globally. However, the sustainability of this industry is under threat due to its reliance on ageing harvest equipment and the resultant environmental impacts. In order to evaluate seed harvesting practices, technology, and issues, we report on case studies, workshops, and a survey of seed producers across southern Australia. The Horwood Bagshaw Clover Harvester, designed in the 1950s, remains the most popular subterranean clover seed harvester. We discuss its use and modifications, and document several contemporary issues facing the seed production industry. Issues are primarily soil erosion and degradation; the expensive, slow and labour-intensive harvest process; and poor reliability and maintainability of harvesters that are now at least 30 years old. We conclude the root cause of these issues is the suction harvest technology utilised by the Horwood Bagshaw Clover Harvester. Analysis of the current harvest system is provided to support the development of new approaches to harvest subterranean clover seeds.

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