Intermittent fault diagnosis and health monitoring for electronic interconnects

Literature survey and correspondence with industrial sector shows that No-Fault-Found (NFF) is a major concern in through life engineering services, especially for defence, aerospace, and other transport industry. There are various occurrences and root causes that result in NFF events but intermittent interconnections are the most frustrating. This is because it disappears while testing, and missed out by diagnostic equipment. This thesis describes the challenging and most important area of intermittent fault detection and health monitoring that focuses towards NFF situation in electronics interconnections. After introduction, this thesis starts with literature survey and describes financial impact on aerospace and other transport industry. It highlights NFF technologies and discuss different facts and their impact on NFF. Then It goes into experimental study that how repeatedly intermittent fault could be replicated. It describes a novel fault replicator that can generate repeatedly IFs for further experimental study on diagnosis techniques/algorithms. The novel IF replicator provide for single and multipoint intermittent connection. The experimental work focuses on mechanically induced intermittent conditions in connectors. This work illustrates a test regime that can be used to repeatedly reproduce intermittency in electronic connectors whilst subjected to vibration ... [cont.]

No Fault Found events in maintenance engineering Part 1: Current trends, implications and organizational practices

This paper presents the first part of a state of the art review on the No Fault Found (NFF) phenomenon. The aim has been to compile a systematic reference point for burgeoning NFF literature, and to provide a comprehensive overview for gaining an understanding of NFF knowledge and concepts. Increasing systems complexities have seen a rise in the number of unknown failures that are being reported during operational service. Units tagged as ‘NFF’ are evidence that a serviceable component was removed, and attempts to troubleshoot the root cause have been unsuccessful. There are many reasons on how these failures manifest themselves and these papers describe the prominent issues that have persisted across a variety of industrial applications and processes for decades. This article, in particular, deals with the impact of NFF from an organizational culture and human factors point of view. It also highlights recent developments in NFF standards, its financial implications and safety concerns

Vehicle-Level Reasoning Systems: Integrating System-Wide Data to Estimate the Instantaneous Health State

At the aircraft level, a Vehicle-Level Reasoning System (VLRS) can be developed to provide aircraft with at least two significant capabilities: improvement of aircraft safety due to enhanced monitoring and reasoning about the aircrafts health state, and also potential cost savings by enabling Condition Based Maintenance (CBM). Along with the benefits of CBM, an important challenge facing aviation safety today is safeguarding against system and component failures and malfunctions. Faults can arise in one or more aircraft subsystem their effects in one system may propagate to other subsystems, and faults may interact

Analysis and restoration of a 1960s ear vacuum tube AM-FM reflex receiver

Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2004.Includes bibliographical references (leaf 59).This thesis details the analysis, restoration, and evaluation of a 1960s era vacuum tube AM-FM reflex receiver. External influences such as tax laws necessitated clever designs to minimize the use of expensive vacuum tubes in radios. The thesis work yielded a thorough description of the circuits, the successful restoration of the radio to nominal operation, and concluded with a brief evaluation of the radio's operating characteristics.by Adam J. Golden.M.Eng

Autonomous Multi-Chemistry Secondary-Use Battery Energy Storage

Battery energy storage is poised to play an increasingly important role in the modern electric grid. Not only does it provide the ability to change the time-of-day and magnitude of energy produced by renewable resources like wind and solar, it can also provide a host of other 3ancillary grid-stabilizing services. Cost remains a limiting factor in deploying energy storage systems large enough to provide these services on the scale required by an electric utility provider. Secondary-use electric vehicle batteries are a source of inexpensive energy storage materials that are not yet ready for the landfill but cannot operate in vehicles any longer. However, the wide range of manufacturers using different battery chemistries and configurations mean that integrating these batteries into a large-format system can be difficult. This work demonstrates methods for the autonomous integration and operation of a wide range of stationary energy storage battery chemistries. A fully autonomous battery characterization is paired with a novel system architecture and transactive optimization to create a system which can provide utility-scale energy services using a multitude of battery chemistries in the same system. These claims are verified using a combination of in-situ testing and a computer modelling testbed. Results are presented which demonstrate the ability of the system to combine a wide range of batteries into an effective single system

Advancing automation and robotics technology for the Space Station and for the US economy, volume 2

In response to Public Law 98-371, dated July 18, 1984, the NASA Advanced Technology Advisory Committee has studied automation and robotics for use in the Space Station. The Technical Report, Volume 2, provides background information on automation and robotics technologies and their potential and documents: the relevant aspects of Space Station design; representative examples of automation and robotics; applications; the state of the technology and advances needed; and considerations for technology transfer to U.S. industry and for space commercialization

Concurrent Measurements of Inflow, Power Performance and Loads for a Grid-Synchronized Cross-Flow Turbine Operating in a Tidal Estuary

The adaptation of sustainable fluid energy conversion technologies, such as wind or tidalenergy, requires numerical modeling tools that are able to accurately predict device performance and loading in an effort to reduce the costs of turbines, deployment platforms and mooring structures. To validate models, data sets from turbines operating in real flow environments are required. Particularly for tidal energy, data sets of inflow (tidal current resource), power performance (electrical power and shaft speed), and thrust loading for any scale device are rare because the work to date has largely been funded by private developers and the data is not made publicly available. This “silos” the development of knowledge around operating devices to individual developers, which slows the pace of commercialization for the technology sector as a whole. The research project presented here utilized an existing tidal turbine, a modified New EnergyCorp EVG-025 vertical axis cross flow turbine (3.2m dia. X 1.7m tall), deployed at the UNH Tidal Energy Test Site at the Memorial Bridge in Portsmouth, NH. Significant improvements were made to the existing system, including the first grid synchronous operation, the development of a new data acquisition system (DAQ) and adding time synchronization across new and existing DAQ’s to allow for accurate performance and load characterization of the device. A significant data acquisition campaign was conducted during the fall of 2021, with over 750kWh hours of renewable tidal energy delivered to the NH grid during 29 days of turbine operation. Turbine power performance and thrust loading was characterized over a range of inflow operating conditions. Spectral analysis indicates the effects of turbulent structures on thrust loading and power output. The results further highlight the need for accurate instrument location and temporal resolution for accurate tidal resource characterization when siting new projects. This data set with all the concurrent measurements is sufficiently detailed for numerical model validation in real tidal flows. After significant quality control (QC) processing, the data set has been published in a public database, MHKR/PRIMRE. (Link: MHKDR-394