Fail-safe Systems Research Articles

Redundancy as a Legal Strategy to Combat Corruption: Exploring the Potential of Institutional Multiplicity to Create Fail-Safe Systems

Abstract Engineering uses duplication to create fail-safe systems. The existence of two system components capable of performing the same function increases reliability, as the supposedly superfluous component can be turned on if the main one breaks down. Although redundancy ensures that many of our modern conveniences such as computers and planes do not crash, this solution has not been extensively explored in a legal context. This article will articulate some of the advantages of redundancy between different areas of the law (administrative, civil and criminal) and at an institutional level (among bodies performing monitoring, investigative, prosecutorial and adjudicative functions in the same and in distinct jurisdictions). Legal efforts to combat corruption around the world provide illustrative examples of the many advantages of this strategy, but also some of its risks and disadvantages. Far from providing a comprehensive empirical analysis of this subject, this article articulates hypotheses to be tested and proposes that the topic deserves more attention among legal scholars than it has received.

Improving the pre-medical emergency team: the case for a behavioural theoretical lens.

There is mounting evidence that the pre-medical emergency team (pre-MET) of rapid response systems is underutilised in clinical practice due to suboptimal structures and processes and resource constraints. In this perspective article, we argue for examining the pre-MET through a 'Behaviour Change Wheel' lens to improve the pre-MET and maximise the associated patient safety benefits. Using pre-MET communication practices as an example, we illustrate the value of the COM-B model, where clinicians' 'capability', 'opportunity', and 'motivation' drive 'behaviour'. Optimising clinicians' behaviours and establishing failsafe rapid response systems is a complex undertaking; however, examining clinicians' behaviours through the COM-B model enables reframing barriers and facilitators to develop multifaceted and coordinated solutions that are behaviourally and theoretically based. The COM-B model is recommended to clinical governance leaders and health services researchers to explore the underlying causes of behaviour and successfully enact change in the design, implementation, and use of the pre-MET to improve patient safety.

Spectral Failsafe System of High-Power Laser Using Dual Fiber Bragg Gratings.

Phase-modulated (PM) spectral failsafe systems are necessary to promptly terminate amplification processes following accidental seeding of a high-power laser chain with a non-PM pulse to prevent optical damage. In this work, we present a reliable spectral failsafe system that can indicate the presence or absence of sufficient PM light. This requirement is met by combining dual temperature-sensitive fiber Bragg gratings detection with high-speed RF amplitude comparisons. The failsafe trigger signal is generated when the spectral power at the peak sideband exceeds that at the center. The spectral failsafe system has the ability to distinguish between adequate and inadequate PM pulses, and it exhibits significant robustness in pulse width, TEC temperature drift, and DFB wavelength drift in experiments, making it valuable for safe high-power laser operations and providing a useful reference for other detection system designs.

Design of the Sabot-Stopping System for a Single-Stage Light-Gas Gun for High-Velocity Impacts

Collisions of space debris and micrometeorites with spacecraft represent an existential hazard for human activities in near-Earth orbits. Currently, guidelines, policies, and best practices are encouraged to help mitigate further propagation of this space debris field from redundant spacecraft and satellites. However, the existing space debris field is an environment that still poses a great threat and requires the design of contingency and fail-safe systems for new spacecraft. In this context, both the monitoring and tracking of space debris impact paths, along with knowledge of spacecraft design features that can withstand such impacts, are essential. Regarding the latter, terrestrial test facilities allow for replicating of space debris collisions in a safe and controlled laboratory environment. In particular, light-gas guns allow launching impactors at speeds in the high-velocity and hypervelocity ranges. The data acquired from these tests can be employed to validate in-orbit observations and structural simulations and to verify spacecraft components’ survivability. Typically, projectiles are launched and protected using a sabot system. This assembly, known as a launch package, is fired towards a sabot-stopping system. The sabot separates from the rest of the launch package, to avoid target contamination, and allows the projectile to travel towards the target through an opening in the assembly. The response and survivability of the sabot-stopping system, along with the transmission of the forces to the light-gas gun structure and prevention of target contamination, is an important design feature of these test apparatuses. In the framework of the development of Malta’s first high-velocity impact facility, particular attention was dedicated to this topic: in this paper, the description of a novel sabot-stopping system is provided. The system described in this research is mechanically decoupled from the interaction with the impact chamber and the light-gas gun pump tube; this solution avoids damage in case of failures and allows easier operations during the pre- and post-test phases.

Технологии применения распределенных вычислений при построении перспективных сбое- и отказоустойчивых орбитальных группировок малых космических аппаратов

The paper examines issues of introducing the distributed computational technologies in constructing the fail-safe and fault-tolerant control systems for spacecraft constellations of various purposes. Various target objectives require various tools to achieve the task. Comparative analysis of the existing distributed computational technologies operating with the responsive application systems was performed including the spacecraft constellation control systems, to identify the most acceptable solutions. Principles of constructing the network-centric systems in controlling the spacecraft constellations were considered. Distributed computational technologies were analyzed not only from the point of view of solving the target problems by the spacecraft constellations, but also from the point of view of ensuring their reliability, as well as in organizing the spacecraft constellation control systems.

Stochastic comparisons of lifetimes of fail-safe systems with dependent and heterogeneous components under random shocks

A fail-safe system is a ( n − 1 ) -out-of-n system whose lifetime is represented by the second-order statistic. This work studies stochastic comparisons of lifetimes of fail-safe systems with dependent and heterogeneous components, where the components are subjected to random shocks instantaneously. The results are derived for a general semiparametric family of distributions of the component lifetimes. We derive sufficient conditions for the comparison results under the usual stochastic order, and we provide counterexamples to show that under those conditions, similar comparisons cannot be made under the hazard rate order.

Reliability analysis of fail-safe systems with heterogeneous and dependent components subject to random shocks

In many significant safety systems, the fault tolerance of a fail-safe system has been a fundamental design attributed to obtaining more higher reliability. However, in most practical scenarios, the components in a fail-safe system suffer from additional random shocks, and one component’s failure may increase the failure probability of other surviving components. This article analyzes the effects of survived probabilities and components lifetimes on the reliability of fail-safe systems with statistically dependent components subject to random shocks in terms of the usual stochastic and hazard rate orderings. Sufficient conditions are established by means of transformation functions, underlying component lifetime distributions, and majorization orders. Some numerical examples are also presented for illustrating our theoretical findings.

Back to the future: Cybernetics for safety, quality and cybersecurity

There is a lack of a holistic framework that ensures Industry 4.0 systems include Internet of Things (IoT) devices and computer systems designed to be fail-safe during cyberattacks. The silo view of treating industrial risk, Information Technology (IT) risk, and software quality as separate fields are leading to exploitable and hackable systems as documented by recent events. A stable system requires the collaboration and integration of engineering experts in quality, software design, reliability along with quality managers and auditors to focus on the intersection of technology and safety/reliability. The field of Cybernetics was originally created as an interdisciplinary field to understand and control complex systems. A multi-faceted and cross-disciplinary approach will be required to design fail-safe systems that can withstand cyberattacks in Industry 4.0. Integrating roles and responsibilities cannot succeed without a similarly aligned cross-functional approach, including a RAIC framework.

Ordering fail-safe systems having dependent components with Archimedean copula and exponentiated location-scale distributions

In this paper, we study stochastic comparisons of two fail-safe systems with dependent components having an Archimedean copula for the joint survival function and general exponentiated location-scale lifetime distributions. We first present sufficient conditions for the usual stochastic order between fail-safe systems when the components have different exponentiated location-scale distributions but with the same Archimedean copula. Next, the hazard rate ordering of fail-safe systems is discussed when the components in the two systems are independent and follow multiple-outlier exponentiated location-scale models. Several examples are then presented to illustrate the theoretical results established here.

Orderings of fail-safe systems with components having Marshall-Olkin-Harris lifetime distributions

In this paper, we discuss stochastic comparisons of two fail-safe systems in two different directions. First, we present sufficient conditions for the usual stochastic order between two fail-safe systems have different lifetime distributions but with the same Archimedean copula for their joint distribution. Next, hazard rate orderings of two fail-safe systems with independent components following multiple-outlier models are established. Several illustrative examples are also presented.

Adaptive Fault Detection and Emergency Control of Autonomous Vehicles for Fail-Safe Systems Using a Sliding Mode Approach

This paper presents a sliding mode-based adaptive fault detection and emergency control algorithm for implementation in fail-safe systems of autonomous vehicles. The overall algorithm is comprised of a fault detection part and a fail-safe control part. For the former, sliding mode observer-based fault detection algorithms were developed for environment and chassis sensors, including LiDAR, Radar, and acceleration sensors. Unidentified fault signals from the sensors are reconstructed through the adaptive sliding mode observer. The reconstruction is based on the MIT rule through the use of an estimated sensitivity parameter. For the latter, a sliding mode control (SMC)-based emergency control method designed to respond to fault occurrences has been proposed to ensure the functional safety of autonomous vehicles. An adaptive gain parameter was designed, taking convergence time into consideration, to secure consistent and rapid responses from the controller. When the detection algorithm detects a fault, the appropriate control input is computed by a lower controller for the vehicle. This control input is calculated based on the last scene information obtained from an upper controller. The performance of the proposed fault detection and control algorithms has been evaluated through simulations and actual vehicle tests of various scenarios.

A Path Dependent Approach for Characterizing the Legal Governance of Autonomous Systems

Autonomous systems promise significant improvements in many fields. These systems will be subject to legal governance requirements. The literature has largely focused on “autonomous governance” as a framework that is broadly applicable to autonomous devices regardless of the type of system ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">e.g</i> ., aviation or motor vehicles) at issue. While there are regulatory principles applicable to autonomous systems generally, an “autonomy-focused” approach is an inadequate lens to consider the governance of these systems. Rather, because autonomous systems are improvements of currently regulated complex systems, the regulation of autonomous elements will occur within those systems’ preexisting regulatory framework. Accordingly, the nature of future autonomous regulation will likely depend on the preexisting features of that substantive system, rather than on an optimal approach divorced from that history, an attribute known in the social science literature as path dependency. In order to characterize diverse regulated systems with an eye toward assessing future autonomous developments, we develop a framework of regulatory approaches to identify specific features of the preexisting regulatory scheme for a given system. We then analyze that approach by examining three different regulatory regimes (aviation, motor vehicles, and medical devices), across two different continents, and consider how the same type of requirement, <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">e.g</i> ., fail-safe systems, can lead to different types of regulations depending on the differing baseline framework.

Emergency Pull-Over Algorithm for Level 4 Autonomous Vehicles Based on Model-Free Adaptive Feedback Control With Sensitivity and Learning Approaches

This paper presents an emergency pullover algorithm for fail-safe systems designed for level-4 autonomous vehicles. The proposed algorithm utilizes feedback gain adaptation, based on sensitivity estimation, and cost-based learning. Vehicle failure within this paper does not encompass every type of failure and refers only to any situation where the upper controller or communications from the upper controller shuts down. When this type of failure occurs, the algorithm performs an emergency pullover maneuver. This maneuver does not require any form of independent control from the driver to be performed successfully. However, the highest control priority is still given to the driver if the driver intervenes during the maneuver. The feedback gain adaptation is comprised of two sections: Sensitivity Estimation and Gradient Descent (GD) based Adaptation. For Sensitivity Estimation, a relationship function has been designed with feedback gain, from the feedback gain adaptation, and changes in state error. The sensitivity of state error with respect to feedback gain can then be estimated. This estimation is done through the Recursive Least Squares (RLS) method with multiple forgetting factors through the directional forgetting method. For GD based Adaptation, state errors are applied with parameters for the cost-based learning to give Adaptation Gains. These Adaptation Gains are used in tandem with the estimated sensitivity to update the feedback gain. To reduce the number of tuning parameters required in the GD method, an additional distance condition has been proposed. This condition utilizes feedback change rates and state errors, obtained from the multi-dimensional plane of the feedback gain’s change rates. A proportional coefficient is also required as a tuning parameter for this condition. This parameter is tuned by a cost-based learning algorithm, also designed in this study. Resultantly, these methods allow the adaptive feedback controller to forgo any system information such as mathematical models and system parameters. This indicates that the vehicle model is not expected to hinder performance. Hence, controllers that do not require system information are indeed a preferable algorithm for fail-safe modules. Performance evaluations for the controller has also been conducted with actual vehicle tests, under longitudinal and lateral autonomous driving scenarios.

Fault-Tolerance by Resilient State Transition for Collaborative Cyber-Physical Systems

Collaborative Cyber-Physical Systems (CCPS) are systems where several individual cyber-physical systems collaborate to perform a single task. The safety of a single Cyber-Physical System (CPS) can be achieved by applying a safety mechanism and following standard processes defined in ISO 26262 and IEC 61508. However, due to heterogeneity, complexity, variability, independence, self-adaptation, and dynamic nature, functional operations for CCPS can threaten system safety. In contrast to fail-safe systems, where, for instance, the system leads to a safe state when an actuator shuts down due to a fault, the system has to be fail-operational in autonomous driving cases, i.e., a shutdown of a platooning member vehicle during operation on the road is unacceptable. Instead, the vehicle should continue its operation with degraded performance until a safe state is reached or returned to its original state in case of temporal faults. Thus, this paper proposes an approach that considers the resilient behavior of collaborative systems to achieve the fail-operational goal in autonomous platooning systems. First, we extended the state transition diagram and introduced additional elements such as failures, mitigation strategies, and safe exit to achieve resilience in autonomous platooning systems. The extended state transition diagram is called the Resilient State Transition Diagram (R-STD). Second, an autonomous platooning system’s perception, communication, and ego-motion failures are modeled using the proposed R-STD to check its effectiveness. Third, VENTOS simulator is used to verify the resulting resilient transitions of R-STD in a simulation environment. Results show that a resilient state transition approach achieves the fail-operational goal in the autonomous platooning system.

Pleasure or Business-Travelling and the Pandemic Virus: Socio Legal Aspect

Ever since the corona pandemic hit the world with full rancour, people have gone into hiding thus restricting movement in all spheres, bringing their movement to a halt. It has been extrapolated since ages that movement of masses is the essence of economics. A man moves to earn, to seek visual pleasure, to seek social contact and as such the freedom to move freely, is both a legal and fundamental right, guaranteed under the Indian Constitution. The following research article aims to study the socio-legal aspect of restricted or altered human movement brought about by the pandemic and its effect on the tourism and hospitality industry. The study findings include the immense loss which the industry has suffered as result of the pandemic, followed by the path forward in terms of the new trends which may emerge in the year 2021, to cope with the loses. A further scope of study in the stated research topic may include developing fail-safe systems as method of check and balance to keep the tourism and hospitality industry afloat, in the event of such unforeseen crisis.

Hybrid skyhook mass damper

The objective of this study is to increase the efficiency of an initial passive Tuned Mass Damper (TMD) by adding an active control unit. A critical issue in many engineering domains is the design of fail-safe active systems. The proposed hybrid system aims to address this issue and realizes the said objective. It emulates the behavior of a skyhook damper parallel to a passive TMD. Skyhook dampers acts like viscous dampers connected to the ground, reducing the vibration amplitudes without any overshoot. It can be difficult to design a specific control law to obtain a desired dynamical behavior. The paper presents two ways to understand and design the hyperstable control law for Hybrid Mass Damper (HMD) (also called Active TMD), using the power flow formulation or the mechanical impedance analysis. These approaches are illustrated through the synthesis of this hybrid device and the emulation of the Skyhook damper. It is shown that a well-designed control law for this kind of system may result in high damping performance, ensuring stability and a fail-safe behavior. In addition, the amplitude of the primary system’s response is reduced over the entire frequency range which is not the case for the usual active or hybrid systems. Robustness is analyzed and compared to that of the classical active mass damper, and an experimental set up validates the proposed hybrid system.

Rotary-Steerable System Concept Aims To Increase Efficiency, Reduce Costs

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of the open-submission paper “Breakthrough Rotary-Steerable System To Reduce Well-Construction and Exploitation Costs,” by François Millet, SPE, Dynasteer, and Christophe Simon and Stéphane Menand, SPE, DrillScan. The paper was not presented at an SPE conference and has not been peer reviewed. The advent of the rotary-steerable system (RSS) introduced an efficient way to drill both current and future wells. However, current tools still fail to replace positive displacement motors (PDMs). High build-rate RSSs that maximize reservoir contact are more expensive than PDMs that deliver consistent and reliable build rates, whatever the formation, while RSS tools with a low cost of ownership may not deliver expected performances. This paper presents a concept that combines optimal functionalities and directional performances with cost-effectiveness. Lessons Learned in the Field Hundreds of potential RSS configurations exist when considering engineering options such as steering principle, geometry, control mechanisms, rotating/nonrotating sections, and power source. In the past, many such systems have been run in two types of bent housing that equipped PDMs. Field experience has shown that an efficient RSS must incorporate features such as the following: High build rates to maximize reservoir contact and deliver vertical, curve, and lateral sections in one run, thereby eliminating flat times A slick, short nonrotating section to enhance reliability through a low-activation-frequency steering unit and consistent build rates without hole-cleaning issues A steady, continuously active, and monitored step-by-step adjustable steering device associated with near-bit continuous inclination and azimuth measurement to drill vertical, curved, and lateral sections in one run with a smooth trajectory that facilitates operations during the whole life of the well In addition, drillers seek timely near-rig maintenance to minimize both downtime and logistics, and all-mud-compatible low-drop-up pressure tools to drill with both the optimal mud formulation and maximum pressure. Failsafe downhole systems that ease the process of pulling out of hole in the event of failure are also beneficial. However, these features are rarely available in a single tool. High-build-rate RSSs are more expensive than PDMs mainly because of maintenance cost and downtime. Most cannot deliver a smooth wellbore because of steering-control issues. Low total-cost-of-ownership rotary-steerable tools have limited functionality and thus in-consistent•performance. Addressing the Issue To engineer an improved RSS, two complementary elements were incorporated: A monobloc flexible drive shaft that maximizes system reliability by carrying both torque and weight on bit (WOB) through the RSS. The short double-tilt unit bent housing, known currently as the point-and-push hybrid steering principle, that provides high build rates with a limited tilt angle. Unlike most designs, the usual nonrotating main body is split into two sections (Fig. 1): first, an upper carrier integrating all sensors, actuators, electronics, and the antirotation unit, and, second, a lower steerable housing integrating the fully mechanical pressurization device. These modules are linked by a monobloc flexible drive shaft acting as both a multidirectional one-piece joint and a return spring.

Safety Standards in Industrial Applications: A Requirement for Fail-Safe Systems

Safety Standards in Industrial Applications: A Requirement for Fail-Safe Systems

Reasons For Lack of Follow-up Colonoscopy Among Persons With A Positive Fecal Occult Blood Test Result: A Qualitative Study.

Follow-up colonoscopy rates among persons with positive fecal occult blood test results (FOBT + ) remain suboptimal in many jurisdictions. In Ontario, Canada, primary care providers (PCPs) are responsible for arranging follow-up colonoscopies. The objectives were to understand the reasons for a lack of follow-up colonoscopy and any action plans to address follow-up. Semi-structured interviews were conducted with 30 FOBT+ persons and 30 PCPs in Ontario. Eligible FOBT+ persons were identified through administrative databases and included those aged 50-74, with a 6-12 month old FOBT+, no follow-up colonoscopy, and no prior colorectal cancer diagnosis or colectomy. Eligible PCPs had ≥1 rostered FOBT+ person without follow-up colonoscopy. Transcripts were analyzed inductively using Nvivo 11 (QSR International Pty Ltd., 2015). Reasons for lack of follow-up colonoscopy were: person and/or provider believed the FOBT + was a false positive; person was afraid of colonoscopy; person had other health issues; and breakdown in communication of FOBT+ results or colonoscopy appointments. PCPs who initially recommended follow-up colonoscopy did not change the minds of the persons who dismissed the FOBT+ as a false positive and/or who were afraid of the procedure. These FOBT+ persons negotiated an alternative follow-up action plan including repeating the FOBT or not following-up. PCPs may not adequately counsel FOBT+ persons who believe the FOBT+ is a false positive and/or fear colonoscopy. PCPs may lack fail-safe systems to communicate FOBT+ results and colonoscopy appointments. Using navigators may help address these barriers and increase follow-up rates.

Application of Failure Mode Effect and Criticality Analysis (FMECA) to a Computer Integrated Manufacturing (CIM) Conveyor Belt

Fault finding and failure predicting techniques in manufacturing and production systems often involve forecasting failures, their effects, and occurrences. The majority of these techniques predict failures that may appear during the regular system production time. However, they do not estimate the failure modes and they require extensive source code instrumentation. In this study, we suggest an approach for predicting failure occurrences and modes during system production time intervals at the University of Hail (UoH). The aim of this project is to implement failure mode effect and criticality analysis (FMECA) on computer integrated manufacturing (CIM) conveyors to determine the effect of various failures on the CIM conveyor belt by ranking and prioritizing each failure according to its risk priority number (RPN). We incorporated the results of FMECA in the development of formal specifications of fail-safe CIM conveyor belt systems. The results show that the highest RPN values are for motor over current failure (450), conveyor chase of vibration (400), belt run off at the head pulley (200), accumulated dirt (180), and Bowed belt (150). The study concludes that performing FMECA is highly effective in improving CIM conveyor belt reliability and safety in the mechanical engineering workshop at UoH.