Bernard Fong

Special Issue on Prognostics and Health Management

Prognostics and Health Management (PHM) is an enabling discipline consisting of technologies and methods to assess the reliability of a product in its actual life cycle conditions to determine the advent of failure and mitigate system risk. It focuses on predicting the future condition of a component and/or system of components. The science and technology of prognostics is based on the analysis of failure modes, detection of early signs of wear and aging in complex systems and components, and correlation of these signs with an aging profile (or model). Potential uses for prognostics include estimation of remaining useful life (RUL) and conditionbased maintenance (CBM). Technological advances in the 21st century have brought about ever-increasing sophistication and miniaturization of products, and systems. Consumer electronics manufacturers, very often release new versions of their products with an increasingly frequency in the hungry world market. These companies not only have to address ever-increasing expectations of customers’ demands, but also have to create a niche in the market so as to stay ahead in the competition. Therefore there is an added pressure on these companies to produce high quality products in a much shorter time. This poses a severe challenge to these companies as they have to achieve cost-effective reliability, availability, maintainability and safety design of their products while at the same time reducing the testing and qualification time. The inability to do so could result in loss of market. Another factor that companies must take into consideration is the conditions of usage that that their products experience as the environmental and operational conditions may vary considerably even with the same product made by a manufacturer. For high value and critical products and systems the major concern is the safety and reliability. For mission-critical systems availability and maintainability of the system is very important. Although two types of general maintenance activities are corrective maintenance and preventive maintenance. And both aim to bring back the product in operational state, a continuous approach to determine the health of the product is needed so that maintenance, repair, and replacement activities are only conducted when necessary. This is known as condition-based maintenance. High operational availability of systems is difficult to achieve because of the lack of understanding of the interactions of performance parameters, application environments and their effect on degradation and failure. Traditional approaches for failure mitigation have typically failed because of the reliance on averaged accumulated historical field data (e.g., MIL-HDBK-217, Telcordia SR332, and CNET/RDF (FIDES)), and typically assume a constant failure rate, rather than relying on in situ data of a particular system. Prognostics and health management (PHM) is an effective way of estimating reliability in situ. A prognostic is the process of monitoring the health of a product and predicting its remaining useful life

Interoperability in a Wireless Home Networking System for Healthcare Monitoring

Versatile wireless home networks provide a convenient means for keeping track of health with appropriate biosensors. It utilizes existing network for A/V and computing applications is presented in this paper. The system provides reliable communication channels for a number of consumer applications while optimal allocation of resources is provided with an interoperability specification for an IEEE 802.11 based network connecting to an external wireless telemedicine system. Each device is identified with an RFID tag and the system allocates necessary network resources with adequate QoS assurance for a given application.

Ubiquitous Healthcare for environmentally linked disease syndromic surveillance

Ubiquitous Healthcare utilizes an array of small low-power environmental sensors for prognosis and diagnosis of health degradation. By focusing on condition-based monitoring of patient behavior and the ambient environment assessment, this paper presents a framework for syndromic surveillance of chronic disease with an emphasis on asthma and control using ubiquitous telemedicine solution. This allows regulation of indoor air quality for a healthy living environment for active prevention and provides a framework for automatic update of electronic patient record. Upon detection of any abnormality, the system can also trigger an alert for immediate medical attention to be provided.

Environmental impact on the reliability of mass produced consumer glucose meters

The soaring number of diabetes patients in many metropolitan cities makes mass-produced wearable glucose meters a very profit sector of the medical device industry. Two vitally important factors in the manufacturing of consumer medical devices are reliability and safety. These devices need to be manufactured at the lowest possible cost and must operate predictably according to design specifications. Since each device produced from one production line will be subject to different operating environment during its useful lifetime, this paper seeks to explore the methodology for optimizing reliability with condition-based monitoring of an individual device.

Reliability assessment of LED backlight in mobile devices

This paper studies the premature failures of LED backlights used in mobile devices that are subject to different use conditions since the life expectancy of an identical electronic component may differ substantially under different operating environments while traditional reliability assessment methods documented in many electronics handbooks failure to address this fundamental difference. The work outlines specific approaches in condition-based monitoring for optimal reliability in the display unit of mobile devices.

Home telemedicine system for chronic respiratory disease surveillance — An automated solution for disease control and management to combat the health impact of indoor air pollution

This paper discusses the utilization of a home wireless telemedicine network for surveillance of chronic diseases linked to indoor air pollution. Inhalation of various chemicals and pollutants on a daily basis is known to be damaging to the respiratory system causing serious health hazards. An automated solution is described for acquisition of data for disease control and management so that the users can be alerted of any impending risk so that appropriate preventive actions can be taken.

Prognostics and network health management for image transmission over wireless telemedicine systems

This paper applies prognostics and health management methodology to network reliability optimization, which is commonly used for condition-based monitoring of system health of electronic devices and systems. It presents simulation results and analysis to show the benefits of the proposed approach.

Systematic translation of VLC decoding trees to processes

The synchronization mechanism of variable length codes (VLC) is often understood using encoding/decoding trees. In an earlier paper, we presented a novel application of Communicating Sequential Processes (CSP) to the modelling of VLC synchronization. That provided a very precise description of the synchronization mechanisms. Underpinned by strong mathematical principle, CSP is a process algebra for describing the patterns of communication and interaction between agents that interact via explicit message passing. This paper presents a systematic translation from VLC encoding/decoding trees to processes to ensure the scalability and applicability of the CSP approach of modelling in this context. The proposed translation algorithm is based on an application of automata theory.

Efficient and reliable video transmission with error localization

The convergence of Internet, multimedia and mobile applications has led to an increasing demand for efficient and reliable video data transmission over heterogeneous networks. Due to their coding efficiency, variable-length codes (VLC) are usually employed in the entropy coding stage of video compression standards. However, error propagation is a major problem associated with VLC. We propose the use of self-synchronizing VLC (SSVLC) to achieve the dual goal of optimal coding efficiency and optimal error localization. Performance evaluation has revealed that the use of SSVLC provides better performance than standard VLC techniques.

Adaptive QoS control for video transmission over band-limited networks

Consumers increasingly demand high quality of service (QoS) for multimedia applications. Application-layer QoS control mechanisms that do not make specific references to coding semantics tend to provide the most robust solutions for delivery of multimedia data over bandlimited networks. We propose an adaptive and robust QoS algorithm for bandlimited networks that integrates explicit receiver-sender rate control, rate shaping with multiple quantization parameters and adaptive FEC.