28 - Inverters

Aggregated results from twenty years of community-engaged assiduous restoration of severely degraded coastal littoral systems in New Zealand (NZ) reveal numerous fundamental and substantive natural improvements to dune form, function, and storm resilience. This is accomplished by simple, low-cost exclusive utilisation of the variably threatened local indigenous dune plant species. These valuable and innovative enhancements succeed countless decades of cascading consequences from numerous impacts instigated by historic (and frequently continuing) damaging effects on those previously natural coastal dune ecosystems – impacts that subsequently induced problematic littoral retreat – the true root cause of prevailing coastal erosion. The durable reversals were often generated in less than two decades, contemporaneously with adverse storm surge and sea level rise conditions. Research reveals many global dune ecosystems are afflicted with analogous normalised degradation and erosion difficulties, with the earliest active circumvention recorded in sixteenth century Denmark (McKelvey 1999). Historic plus current pressures such as coastal settlement impacts and continuing agricultural use of dunelands similarly threaten numerous global littoral margins, alongside recent concerns regarding the compounding effects of climate change. Successful, affordable, diligent dune restoration work pioneered in NZ has extensive benefits for other nations experiencing similarly challenging attrition on degraded coastal zones. Persuasive data is presented to validate the numerous persistently accrued benefits of this cost-effective and enduring coastal adaptation response.

Iron sulfide scale is found almost ubiquitously in maturing oilfield produced water handling and injection systems. Keeping injection systems clean of sulfide scale is becoming more of a shared challenge, but there are few examples where true root cause analysis has led to specific laboratory testing and development of bespoke removal and prevention methods. This paper aims to link these aspects by sharing the best practices from around the world with cutting edge techniques and chemistries used to maintain flow assurance and injectivity in produced water handling systems affected by iron sulfide scale. Discussion includes root causes analysis of iron sulfide scale formation and deposition mechanisms focusing on the interplay of pH, along with sources of iron and sulfide. The paper goes onto discuss laboratory and field evaluation of control methods. Finally, the root causes of iron sulfide scale formation and deposition mechanism, including the relative advantages and merits of the different techniques, including: Chelating agents (for iron sequestration) Surfactants (for water wetting) Biocide (to target SRB and biofilm) Corrosion inhibitor (to lower iron in system) Sulfide scale inhibitors (threshold inhibition of scale) Additionally, case histories are used to elaborate the theoretical discussion. The first case history is from an offshore oilfield water injection system, where fouling occurred due to changes in the flow assurance strategy further upstream and capture the lessons learned on the interplay of different production chemicals. The second case history concerns an onshore oilfield with a vast water injection system of over 3,000 wells supporting approximately 5,000 production wells. The paper concludes with a summary of the decades of experience of solving the most challenging sulfide scaling scenarios, as well as cutting-edge research on a new class of polymeric exotic sulfide scale inhibitor dispersant, effective as threshold concentrations against even lead and zinc sulfide.

Modern large frame F, G, & J class gas turbine flow path component design requires the complex integration of multiple design disciplines that traditionally reside with distinct specialists. A traditional design system for an actively cooled gas turbine blade includes aerodynamicists, heat transfer engineers, structural engineers and a failure or lifetime prediction engineers passing information through a manual process with a small number of iterations between the disciplines. Design or manufacturing engineers can also be involved ensuring manufacturability and policing best practices in a predominantly deterministic design system. Over the past few decades robust design or probabilistic design philosophies along with cluster computing advancements have accelerated the release of commercial software that allows for the automation of multiple analytical evaluations at off design points. These software codes allow for process automation of several independent codes executed multiple times at various conditions for automated design of experiment (DOE), and reliability analysis using Monte Carlo or other advanced approximate probabilistic methods across the entire design system. In this paper, the authors are presenting a novel approach of using a commercially available process integration tool to fully integrate a series of other commercially available tools for a root cause failure analysis of a F class turbine blade rather than a new make design. The analysis incorporated a computational fluid dynamics model (CFD) to define inlet temperatures and pressure profiles, a fully conjugate thermal analysis interacting with a finite element (FEA) solver linked to a proprietary creep lifetime prediction model. A DOE was executed to define the meaningful parameters and help rule out potential causes of failure such as loss of coating or compromised cooling system as a contributing factor of the failure which greatly reduced the amount of time and money needed for the investigation. A probabilistic failure analysis was then executed and surrogate models created for quick probabilistic assessment for different operating conditions. This allowed for validation against fleet history to explain the single engine failure not previously observed. Setting up the non-deterministic models initially allowed for rapid redesign in less than 1 month time with confidence that the true root cause was identified and mitigated. It further allowed for feedback and calibrations to the traditional design system methodology.

The paper reports the investigation on the root cause of source-drain leakage in bulk FinFET devices. While the failing device was readily isolated by nanoprobing technique and the electrical analysis pinpointed the potential defect location inside the Fin channel, the identification of physical root cause went through extreme challenges imposed by the tiny-sized device and the unique FinFET 3D architecture. The initial TEM analysis was misled by the projection of a species in the lamella surface and thus could not explain the electrical data. Careful analysis on the device structure was able to identify the origin of the species and led to the discovery of the actual root cause. This paper will provide the analysis details leading to the findings, and highlight the role of electrical understanding in not only providing guidance for physical analysis but also revealing the true root cause of failure in FinFET devices.

Historically, the most common failure analyses metrologies have been dye-and-pull, cross-sections, microscopy, optical and SEM. Using these traditional metrologies to find a root cause from a dynamic event can be very time consuming and sometimes inconclusive. The standard methodology is to work backward to reconstruct the “event” that caused or initiated failure. Often times the root cause is not immediately obvious and design improvements require an iterative process to identify the true root cause. This approach is costly in time, materials and resources. A high speed camera (HSC) allows identification of failure from a point of initiation. Using the point of initiation concept with reconstructive modeling allows a design team to discover potential initiating sources and better match a cause to the effect and implement corrective action. This decreases development time, minimizing product design cycle and increases market opportunities.

A new evolution in graph modeling for conflict resolution (GMCR), a robust methodology for conflict resolution, is presented in this research to incorporate the systems thinking concept into the conventional paradigm of GMCR so that the dynamic nature of water–environmental conflicts can be modeled, and better outcomes obtained. To achieve this objective, a methodology is developed in three phases: static, dynamic, and outcome-based analyses. To develop the methodology, the Tigris–Euphrates basin conflict in the Middle East over the past 30 years, as a real-life case study, is used to show the robustness and capabilities of the proposed approach. Finally, a sustainable resolution to the current conflict is proposed, and the results are discussed. The proposed methodology benefits from improving the existing and often static-based conflict resolution developments by considering the dynamic nature so that the true root causes of complex conflicts are addressed, better strategic insights achieved, and comprehensive resolution provided.

Chapter 15 - Failure-Mode Analysis

This paper describes a new LIT technique named External trigger Synchronous LIT (ESLIT). LIT is widely used in device analysis from initial investigation to fault isolation. This technique uses a “lock-in function” to reduce thermal spreading from the heat source. Conventional LIT analysis is usually performed under limited set-up conditions with some probes without ATE. However, in the case of ESLIT, ATE can be used to reproduce the failure state of the DUT during the LIT analysis. And the “lock-in function” is used to identify specific hotspots that correspond to IDDQ failure states. In our experiment, the results of ESLIT perfectly agreed with IDDQ fault diagnosis candidates. On the other hand, PEM and OBIRCH detected not only logic-related points, but also non-logic-related points that did not match the fault diagnostic results. We also confirmed that ESLIT is available nondestructively. We think that ESLIT is a useful technique for IDDQ failure analysis since it can identify the true root cause even in the case of multiple failure.

During production build using X's Connector, line has high fallout for non-wetting phenomenon and lead observe severe black signature on connector lead after wave soldering process. Thus, fallout rate was 33%. There was severe black signatures were observed on the connector lead due to presence of unwanted elements on the surface of pre-tinned layer during the wave soldering process. The base metal oxidation (zinc oxide) due to low nickel thickness on the inner row pins of ‘failed’ connectors identified as one of the key factors that attributed to the darkening (black) of contacts. In addition, the solid state diffusion is a subject of basic importance for understanding mass transport phenomena in surface of the connector leads. In the particle aspect of surface diffusion of single atoms and simple molecules, information of interest is the detail atomic diffusion mechanisms and the activation energy of the various atomic processes (atomic diffusion occurs during heat treatment), and also the binding energy of atoms at different surface sites. Surface of materials, the top few atomic layers of the connector lead, are of critical importance because it is here that a material interacts with its environment. The surface properties of materials dominate their corrosion behaviour, wettability, electrical contact resistance, frictional behaviour, adhesion properties and chemical reactivity. Therefore, surface analyze techniques was performed in terms of X-ray Photoelectron Spectroscopy (XPS) on the surface composition of electronic connector lead specimens following various mechanical, chemical, electrochemical or thermal treatments has been studied. It was found that as received pre-tinned surface of the connector lead was contaminated by the oxides of zinc due to the step-wise migration of atoms from lattice site to lattice site (diffusion at atomic level). In short, Zinc/Zn present on the Nickel/Ni surface during soldering can easily oxidize and may prevent wetting. For experts’ point of view, even though the atomic % of Zn is small, but it is a true root cause for the oxidation and lead to the black signature [it will slowly oxidize when subjected to multiple heat cycles] . Then, the degradation can start from the first dip in molten Sn-Pb solder and followed by the next heat cycles. The higher the temperature and the longer the time at this temperature, the more Zn atoms will diffuse out from a lead frame material through the Ni layer [especially if the layer is thin – porous] . Moreover, the enlargement of porosity obtained naturally when exposing to any heat cycles. So, more pre-tin steps we have, the higher the risk of Ni, Zn, Sn, intermetallic oxidation, solderability may be significantly affected, and Zn will exaggerate this problem. On the other hand, the electroplating of Ni and good values of plating efficiency needs enhancement in eliminating such defect prior to multiple heat cycles involved during pre-tinning and soldering.

Nowadays, development has become a natural part of our lives, the dynamics and types of which are the only things we tend to highlight and compare. This is why it may seem unusual that science has identified an anomaly in certain territorial units where there is a lack of development. This situation has been called the development trap. The development of an area is, of course, dependent on a great many factors, so that the range of development traps seems almost inexhaustible. This paper takes stock of the development traps identified so far, not with the aim of questioning the methods used, but to evaluate the data and indicators used to identify them. The study concludes that macro-level data are not causes but consequences, masking the true root causes of problems, but they play an important role in establishing a diagnosis at the regional level. The study aims to provide a convincing illustration, using concrete examples, of the development policy approach - and its main features - that can help to overcome the various pitfalls.

The growing adoption of electric vehicles has recently attracted increasing attention of scientists and brought about pioneering research studies from various fields. Safety concerns particularly those regarding ground faults detection and protection, have extensively been addressed. Ground faults occur quite frequently in electric vehicles and they may be due to severe operation conditions, such as vibrations, twists or even crashes. Generally, the first ground fault is not dangerous, since the powertrain systems, namely, the dc bus where the batteries are connected, the power inverter and one or more ac machines, are generally ungrounded. The second ground fault, however, can produce malfunction in some systems, power loss or even serious damages. Locating the fault has often proved hard and time consuming. For this reason, the present study focuses on developing a ground-fault detection method for electric vehicles capable of determining on which side, the dc or the ac, the ground fault is located. The method is based on the analysis of the voltage in a grounding resistor connected between the midpoint of the battery pack and ground. Based on the polarity and harmonics, it is possible to locate the ground fault. This method has been verified excellent results have been achieved using computer simulations and experimental tests in a 140-kW electronic power inverter fed by a 480 Vdc battery.

This paper discusses the performance analysis effort being carried out in the NASA Deep Space Network. The activity involves root cause analysis of failures and assessment of key performance metrics. The root cause analysis helps pinpoint the true cause of observed problems so that proper correction can be effected. The assessment currently focuses on three aspects: (1) data delivery metrics such as Quantity, Quality, Continuity, and Latency; (2) link-performance metrics such as antenna pointing, system noise temperature, Doppler noise, frequency and time synchronization, wide-area-network loading, link-configuration setup time; and (3) reliability, maintainability, availability metrics. The analysis establishes whether the current system is meeting its specifications and if so, how much margin is available. The findings help identify the weak points in the system and direct attention of programmatic investment for performance improvement.

Every year preventable adverse events endanger a considerable number of patients. Current guidelines of the Federal Joint Committee require clinical quality management to provide amongst others an independent clinical risk management and a critical incident reporting system (CIRS). Such guidelines increase the pressure to actively deal with errors, even in emergency medicine. Human error is considered to be the main cause of preventable adverse events in high-risk industries, such as aviation. This observation is gladly directly transferred to clinical medicine. This study investigated where the true causes for preventable adverse events during the resuscitation of severely injured patients can be found. A non-systematic literature search of the PubMed database was performed. The search identified three recent studies addressing these objectives that revealed human error as the most important cause of preventable adverse events during emergency room resuscitation (88-97%). Errors during resuscitation in the emergency room occur in approximately 10 %. It is striking that such data do not differ greatly from findings described in studies undertaken 20 years ago. One possible explanation might be that the systematic evaluation of medical errors in the emergency room is a weak spot and that too few lessons can be learnt from such incidents. Therefore, this article describes models of error development and outlines methods to collect data for root cause analysis and for clinical risk management. Thus, this review aims at a better understanding of how errors originate and to allow development of strategies to prevent errors from happening again. Human error is the most important cause of preventable adverse events during emergency room resuscitation. Presumably, errors occur unintentionally and as a result of situational misjudgment. As such errors have marked consequences on mortality and morbidity of severely injured patients, an extensive risk management is mandatory for the improvement of quality and safety. Appropriate methods to record errors in order to allow a correct root cause analysis according to well-established protocols is a basic prerequisite.

Top four types of sentinel events in Saudi Arabia during the period 2016-19.

BackgroundThrough in-depth identification of management system and specific control factor, the root cause of the accident can be determined. Had been an accident in the PT.X such as a first...