Towards Transparency of IoT Message Brokers

In this paper we propose an ontological model for documenting provenance of MQTT message brokers to enhance the transparency of interactions between IoT agents

A study on helicopter main gearbox planetary bearing fault diagnosis

The condition monitoring of helicopter main gearbox (MGB) is crucial for operation safety, flight airworthiness and maintenance scheduling. Currently, the helicopter health and usage monitoring system, HUMS, is installed on helicopters to monitor the health state of their transmission systems and predict remaining useful life of key helicopter components. However, recent helicopter accidents related to MGB failures indicate that HUMS is not sensitive and accurate enough to diagnose MGB planetary bearing defects. To contribute in improving the diagnostic capability of HUMS, diagnosis of a MGB planetary bearing with seeded defect was investigated in this study. A commercial SA330 MGB was adopted for the seeded defect tests. Two test cases are demonstrated in this paper: the MGB at 16,000 rpm input speed with 180 kW load and at 23,000 rpm input speed with 1760 kW load. Vibration data was recorded, and processed using signal processing techniques including self-adaptive noise cancellation (SANC), kurtogram and envelope analysis. Processing results indicate that the seeded planetary bearing defect was successfully detected in both test cases

Helicopter gearbox bearing fault detection using separation techniques and envelope analysis

The main gearbox (MGB) is a crucial part of a helicopter. MGB bearings suffer intensively from stress and friction during flights hence concerns for their health condition and detecting potential defects become critical for the sake of operation safety and system reliability. In this study, bearing defects were seeded in the second epicyclic stage bearing of a commercial Class A helicopter MGB. Vibration and tachometer signals were recorded simultaneously for the purpose of fault diagnosis. The tests were carried out at different power and speed conditions for various seeded bearing defects. This paper presents a comparison of signal processing techniques employed to identify the presence of the defects masked by strong background noise generated from an operation helicopter MGB

Using empirical mode decomposition scheme for helicopter main gearbox bearing defect identification

© 2016 IEEE. Vibration sensors for helicopter health and condition monitoring have been widely employed to ensure the safe operation. Through the years, vibration sensors are now commonly placed on helicopters and have claimed a number of successes in preventing accidents. However, vibration based bearing defect identification remains a challenge since bearing defects signatures are usually contaminated by background noise resulting from variable transmission paths from the bearing to the receiving externally mounted vibration sensors. In this paper, the empirical mode decomposition (EMD) scheme was utilized to analyze vibration signal captured from a CS29 Category 'A' helicopter main gearbox, where bearing faults were seeded on one of the planetary gears bearing of the second epicyclic stage. The EMD scheme decomposed vibration signal into a number of intrinsic mode functions (IMFs) for subsequent envelope analysis. The selection of appropriate IMFs to characterize bearing fault signatures was discussed. The analysis result showed that the bearing fault signatures were successfully characterized and revealed the efficacy of the EMD scheme

Using independent component analysis scheme for helicopter main gearbox bearing defect identification

© 2017 IEEE. Vibration signal analysis is the most common technique for helicopter health condition monitoring. It has been widely employed to detect helicopter gearbox fault and ensure the safe operation. Through the years, vibration signal analysis has a significant contribution to successfully prevent a number of accidents. However, vibration based bearing identification remains a challenge because bearing defects signatures are contaminated by strong background noise. In this paper, the independent component analysis (ICA) scheme was utilized to analyze vibration signals captured from a CS29 Category 'A' helicopter main gearbox, where bearing faults were seeded on the second epicyclic stage planetary gears bearing. The ICA scheme could separate the multichannel signals into the mutually independent components. The bearing defect signature can be clearly observed in one of the independent components. The analysis result showed that ICA scheme is a promising method for detecting the bearing fault signatures

Application of Fieldbus Technology to Enable Enhanced Actuator Control of Automated Inspection for Offshore Structures

Due to extreme environmental loadings and aging conditions, maintaining structural integrity for offshore structures is critical to their safety. Non-destructive testing of risers plays a key role in identifying defects developing within the structure, allowing repair in a timely manner to mitigate against failures which cause damage to the environment and pose a hazard to human operators. However, in order to be cost effective the inspection must be carried out in situ, and this poses significant safety risks if undertaken manually. Therefore, enabled by advancements in automation and communication technologies, efforts are being made to deploy inspection systems using robotic platforms. This paper proposes a distributed networked communication system to meet the control requirements of a precision rotary scanner for inspection of underwater structures aimed at providing a robotic inspection system for structural integrity in an offshore environment. The system is configured around local control units, a fieldbus network, and a supervisory control system accounting for the environment conditions to provide enhanced control of actuators for automated inspection of offshore structures

Automated Application of Full Matrix Capture to Assess the Structural Integrity of Mooring Chains

In-service mooring chains are subjected to harsh environmental conditions on a daily basis, which increases the necessity of integrity assessment of chain links. Periodic structural health monitoring of mooring chains is mandatory and vital in order to maintain the safety of floating platforms. Applications of ultrasound for in-service mooring chain inspection is still in its infancy due to lack of accessibility, in field operational complexity and the geometrical features of mooring systems. With the advancement of robotic/ automated systems (i.e. chain climbing robotic mechanisms), interest for in-situ ultrasound inspection has increased. Presently, ultrasound inspection has been confined to the weld area of the chain links. However, according to recent studies on fatigue and residual stresses, ultrasound inspection for the chain crown should be further investigated. A new application of ultrasonic phased array full matrix capture is discussed in this paper for investigation of the chain crown. Due to the complex geometry (i.e. curved and limited access) of the chain crown, a surface mapping technique has been added to the presented full matrix capture technique. The inspection method presented in this study is suitable for both air and underwater chain links. A continuous water supply wedge was developed in order to supply couplant for in air inspection. Development of a technique which can be adapted for robotic inspection is considered, and an automated manipulator was used to carry out inspections. The design of the inspection method and the robotic manipulator has been discussed in this article. The technique is validated with laboratory experiment

Feasibility study on using thioether as an emergency backup lubrication system on a large helicopter main gearbox

The oil lubrication system is a critical part of the helicopter main gearbox (MGB) and this is evident in the many accidents and incidents over the last 30 years. On a category A rotorcraft, a regulatory requirement mandates the MGB to sustain operation for at least 30 minutes following the loss of the primary oil lubrication pressure. The aim of this study was to undertake a comparative investigation into the performance of mist lubrication, using commercially available thioether (MCS-293™), on a category A helicopter MGB under loss of oil conditions. Experimental observations highlighted that the high-speed input module of the MGB attained the highest temperature and was a limiting factor to continued gearbox operation under loss of oil conditions. Results showed that by routing thioether mist through existing galleries within the MGB a lower rate of temperature increase was achieved, in comparison with a dry-run conditio

Performing the Digital Self: Understanding Location-Based Social Networking, Territory, Space, and Identity in the City

Expressions of territoriality have been positioned as one of the main reasons users alter their behaviors and perceptions of spatiality and sociality while engaging with location-based social networks (LBSN). Despite the potential for this interplay to further our understanding of LBSN usage in the context of identity, very little work has actually been done towards this. Addressing this gap in the literature is one the chief aims of the article. Drawing on an original six-week study with 42 participants utilizing a bespoke LBSN entitled ‘GeoMoments’, our research explores: (1) the way that territoriality is linked to self-identity; and (2) how this interplay affects the interactions between users as well as the environments they inhabit. Our findings suggest that participants affirmed their self-identity by selectively posting and claiming ownership of their neighborhood through the LBSN. Here, the locative decisions made related to risk, hierarchies, and the users’ relationship to the area. This practice then led participants to discover and interact with the digital information overlaying their physical environments in a playful manner. These interactions demonstrate the perceived power structures that are facilitated by identity claims over a virtual area. In the main, our results reaffirm that territoriality is a central concept in understanding LBSN use, while also drawing attention to the temporality involved in user-to-user and user-to-place interactions pertaining to physical place mediated by LBSN

Digital Radiography Inspection of Flexible Risers in Offshore Oil and Gas Industry

This paper presents the development of a digital radiography-based system for sub-sea applications that is being implemented within the context of a H2020 EU funded project called "RiserSure". The system is capable of performing semi-automatic in-situ integrity inspections and providing detailed information on any damage to the metallic layers of flexible risers, without the need to remove the coating layer. The integrated system comprises a subsea digital radiography linear detector array coupled to a commercially available marinised gamma ray source, and a bespoke developed versatile scanning system for deploying the radiography units under subsea conditions for performing precise all-round scanning of risers. Preliminary site shallow sea trials of the prototype system were conducted at the Underwater Centre facilities in Fort William, Scotland. The results, discussed in this paper, validated the effective underwater application and performance capabilities of the system in controlled shallow sea operating conditions, and show the potential for offering reliable and highly accurate radiographic inspection of risers. Finally, from the site trials, the requirements for further system improvements were identified for real-world deployment