Redundancy techniques like duplication and Triple Modular Redundancy (TMR) are widely used to design fault-tolerant systems. In this paper, for the first time, we develop fault models for common-mode failures (CMFs) in redundant systems and describe techniques to design redundant systems protected against the modeled CMFs. We first develop an input-register-CMF model that targets systems with r...

Recent models for the failure behaviour of systems involving redundancy and diversity have shown that common mode failures can be accounted for in terms of the variability of the failure probability of components over operational environments. Whenever such variability is present, we can expect that the overall system reliability will be less than we could have expected if the components could ...

By anaizng the stares of novledge Li 'he processors attain 19 an urre as.e SYS Tern of a sImp.e tYpe. we capture some o: :rs;c uxder!ying struc t ire of such svsams. particu ar. we study s hat facts become 'on mu kit 0 uiedgc at var:ous ponts in the execu ion of protoco!s n an un reliable system. This characterizes the sirnu Itaneous ac ions hat can he carHed 0:': in s:ch systems. For et ne. we...

In passenger operation, one often is concerned with on-time performance. On-time performance in commuter operation is measured by the difference between the actual arrival or departure time and scheduled arrival or departure time, respectively. A common practice is to use a time threshold value, and measure the schedule deviation. If the schedule deviation is greater than the set threshold valu...

Modern distributed systems (“cloud systems”) have emerged as a dominant backbone for many today’s applications. They come in different forms such as scale-out file systems, key-value stores, computing frameworks, synchronization and cluster management services. As these systems collectively become the “cloud operating system”, users expect high dependability including performance stability. Unf...

Success for many businesses depends on their information software systems. Keeping these systems operational is critical, as failure in these systems is costly. Such systems are in many cases sophisticated, distributed and dynamically composed. To ensure high availability and correct operation, it is essential that failures be detected promptly, their causes diagnosed and remedial actions taken...

The validity of previous human factors data may be called into question when technology changes rapidly or new and radical designs are introduced as with the advent of unmanned aircraft systems (UASs). The purpose of this study was to analyze the role and pattern of active and latent human failures in USAF MQ-1 Predator UAS mishaps using the Human Factors Analysis and Classification System. A m...

OBJECTIVES The aim of the present study was to determine radiographically the different reasons and problems of endodontic treatment failure. METHODS The periapical radiographs of 100 patients with one hundred teeth (130 root canals) were examined to identify the problems and failures of endodontic treatment. The various reasons of failure that is under filling, poor filling, over filling and...