Failures In Technical Systems Research Articles

Методологічний підхід до розв’язання проблеми надійності функціонування автомобільних транспортних систем

An analysis of methods and techniques for solving the problem of increasing and ensuring the appropriate level of reliability of technical systems was carried out, which made it possible, based on the use of analogies, to find out the directions for ensuring the reliability of automobile transport systems. The essence of the concept of the reliability of the functioning of automobile transport systems for the transportation of goods and passengers from a methodological point of view is clarified. The insufficiency of regulatory and legal documentation for the development of methods and techniques for assessing the reliability of transport systems is substantiated. The synthesis of the concepts of "management" and "reliability" of the functioning of transport systems in comparison with similar concepts of technical systems is considered. The expert method and methodology of expert assessment of the reasons for failures of the production subsystem of the motor vehicle enterprise and its services are considered. It was found that factor analysis in combination with expert assessment makes it possible to assess the significance of the reasons for failure of transport systems and their frequency. In accordance with the classification of failures of technical systems, an analysis of their belonging to automobile transport systems was carried out. The classification of failures of technical systems according to different sets of features is analyzed. It was established that the classification of failures of automobile transport systems is based on the use of analogy with the classification of failures of technical systems, as well as on the results of the analysis of the factors of the causes of failures that occur in the production system of the carrier's enterprise. It was revealed that the selection of significant factors affecting the failure of automobile transport systems is based on the method of expert evaluations, their ranking by importance was carried out, and their relative frequencies were calculated. The results of the factor analysis of the reasons for the failure of the production subsystem of the motor vehicle enterprise are given. It is assumed that by analogy with technical automobile transport systems, they are also subject to decomposition by stages of the life cycle. Therefore, a sudden failure of automobile transport systems is characterized by a sudden change in the values of one or more initial parameters agreed with the customer, and a gradual one occurs as a result of a slow, gradual deterioration of the functioning characteristics of the subsystem or the system as a whole or a participant in the transportation of goods and passengers.

ASSESSMENT OF RISK TO DISTRIBUTION WORKERS

This article presents an analysis of the risk to workers maintaining the medium-voltage facilities of distribution companies, as derived from a series of investigations (injuries at work, time spent on equipment maintenance, ground faults and failures in the grounding system) and represents a group of all the relevant information collected on hazards to workers. The importance of this study is that it is basically concerned with failures, stoppages and interruptions but also repairs (the forecasting, detecting and eliminating of failures), maintenance, replacement, advancements and improvements in the technical systems, as well as the consequences of failures in technical systems and the surroundings thereof. Electricity distribution workers spend most of their working time on the tasks of maintaining electric power facilities, i.e. electricity networks and medium-voltage and low-voltage electric power facilities. While they are working, they are in a potentially hazardous environment that can endanger their health and lives. Naturally, they must be trained to work in a safe manner and use protective equipment. This does not completely eliminate the hazards but in this way the potential for injury and the severity thereof are reduced. All companies, including those engaged in the distribution of electrical energy, take costs into account, much of which are for human labor. Worker injury during working time is also an expenditure, due to sick leave and potential damages, which will be increasingly significant factors in company operations. Therefore, it is important to review all the potential hazards that can endanger the health and life of a worker during maintenance work. The management of such risks will become a growing task for all companies, less for humane reasons than for keeping costs under control.

Vyznachennia ta upravlinnia zahrozamy u strukturi derzhavnoi polityky zakhystu krytychnoi infrastruktury

The article analyses the theoretical approaches to the content of the concept of «critical infrastructure protection». It is determined that the key emphasis in most approaches is on the problems of threats and risks of their occurrence for critical objects. It is noted that the foundation of the scientific substantiation of the state policy of critical infrastructure protection should be formed on the basis of theoretical and methodological approaches to the detection and management of these categories. The greatest danger to the functioning of critical infrastructure in Ukraine is recognized as military threats and risks of emergencies at critical facilities. The analysis of scientific developments on identification of the definition of «critical infrastructure security risk» in the state protection policy is carried out. It is disclosed as the probability of an accident, danger, accident or catastrophe in the operation of critical infrastructure. Management takes place in conditions of uncertainty and the need to predict many alternative situations. It is emphasized that the variety of problems of critical infrastructure protection determines the need for systematic risk analysis in security management (risk analysis). Features of critical risk analysis are the analysis of potentially negative consequences arising from the failure of technical systems, failures or errors by personnel of the facility. Emphasis is placed on the component of «critical risk management» as the main component of the state policy of critical infrastructure security. This category is analysed from the standpoint of administration and management. The conclusion is made that it is necessary to supplement the state policy of critical infrastructure protection with «critical risk management». The result will be a stronger component of the protection of public and private critical facilities. It is determined that making managerial decisions within the proposed critical risk management is carried out in conditions of uncertainty. To solve such problems, it is proposed to use the theory of fuzzy logic as a means of modelling.

The Use of a Fault Tree Analysis (FTA) in the Operator Reliability Assessment of the Critical Infrastructure on the Example of Water Supply System

Background: Specialist literature indicates a large share of the human factor among the causes of failure of technical systems at the level of 70 to 90%, which depends on the sector studied. The collective water supply system is an anthropotechnical system, i.e., it is a complex connection between man and the technical system resulting from the deliberate influence of man on the technical system. Methods: The work presents an assessment of operator reliability of a selected water treatment process based on the fault tree analysis (FTA). Elementary events are determined by the operator’s error probability. Results: A failure tree was prepared for the peak event of the filter station failure, resulting from an operator’s error during the filter washing procedure. The probability of a peak event occurring is 0.0580. Conclusions: The developed fault tree allows for the identification of elementary events leading to an emergency event. The operator fulfills its task of maintaining the continuity of water treatment.

Incorporation of technical, human and organizational risks in a dynamic probabilistic fire risk model for high‐rise residential buildings

SummaryWhile probabilistic risk assessment (PRA) is an explicit methodology for complying with the performance requirements of the Building Code of Australia (BCA) or similar codes, it traditionally focuses only on technical risks of fire safety systems in a building. There are growing concerns that performance‐based fire engineering designs underestimate safety risk levels in high‐rise residential buildings. Existing fire risk models account for failures of technical systems but ignore human and organizational errors (HOEs) and the complex interactions among these variables. Probabilistic models in other applications, such as offshore platforms and nuclear plants, demonstrate the importance of HOE inclusion in risk models and the resulting impacts on overall risk. This paper proposes a comprehensive technical‐human‐organizational risk (T‐H‐O‐Risk) methodology to enhance the PRA approach by quantifying human and organizational risks in a probabilistic model using Bayesian Network (BN) analysis of HOEs and System Dynamics (SD) modelling for dynamic characterization of risk variations over time. While risk modelling itself is not novel, the current research develops unique and specific enhancements to existing risk approaches by integrating HOE risks with technical risks in a comprehensive dynamic and probabilistic model for high‐rise residential buildings. Three case studies are conducted to demonstrate the application of this comprehensive approach to the designs of various high‐rise residential buildings ranging from 18 to 24 storeys. Societal risks are represented in F‐N curves. Results show that in general, fire safety designs that do not consider HOEs underestimate overall risks generally by~20%—and can reach up to 42% in an extreme case. Furthermore, risks over time due to HOEs vary by as much as 30% over a 10‐year period. A sensitivity analysis indicates that deficient training, poor safety culture and ineffective emergency plans have significant impact on overall risk.

Detection of failures of technical systems by forecasting time series

The paper considers the algorithm of diagnostics of the technical system States at future time points by extrapolation of the results of current observations using a genetic algorithm. The novelty of this work lies in the fact that the proposed algorithm is able to generate predictions of technical system States using predictive algorithms and mathematical rules. The paper offers an original view on the use of genetic algorithm as an independent predictive algorithm. The described algorithm is a combination of a modified genetic algorithm and a number of mathematical rules. So, as a modification of the genetic algorithm, its parallel variant (island model) is used, and as a fitness function, a function is used that tests new alternative solutions for distance from the geometric representation of the averaged values of the time series graph. The algorithm performs prediction for a given number of time intervals ahead, for processes that are affected by a limited number of external factors. The efficiency of the algorithm was confirmed by an experiment, which resulted in a predictive solution, the General direction of the process (which was tested in practice).

METHODS MODELING SYSTEMS FOR THE IMPROVEMENT OF THEIR RELIABILITY


 
 
 
 The method of Markov’s processes for the analysis of systems with constant bounce and recovery intensities considered. The article presents calculations of the failure probability of the system for describing the various cases of redundancy of its components using Markov’s models. Expressions obtained for calculating the approximate value of the failure probability of the system and analyzed of failures to improve the reliability of the system. The Markov’s graph of transitions in the reservation of the system, which reflects its behavior, described. Analysis of the results of numerical solution of systems shows that when loaded with redundancy, the probability of failure is higher than with partially loaded, and with partially loaded - higher than with unloaded backup. A tree of errors for the system of cooling and clearing of flue gas at the reservation made by replacing "2 of 3", which has seven minimum bounce cross sections. Calculated the probability of system failure. The obtained calculations allow to analyze failures of technical systems in order to increase the reliability of their functioning.
 
 
 

Statistical modeling of tree failures during storms

The failure of trees during storms imposes strong economic and societal costs. Statistical modeling for predicting the probability of a tree failing during storms has the potential to help improve tree risk management. The purpose of this study is to explore the potential predictability of tree failure using advanced predictive modeling approach. These models also have broader applicability for modeling failures of technical systems during adverse weather events. To train and test models, we use a data set from a real case study in Massachusetts, USA. We compare the out-of-sample predictive accuracy of several machine learning models including logistic regression, classification and regression trees, multivariate adaptive regression splines, artificial neural network, naive-Bayes regression, random forest, boosting, and an ensemble model of boosting and random forest. Our results demonstrate that the ensemble model of boosting and random forest achieves the best prediction accuracy in predicting the failure probability of trees for the case study storm. Our results can help tree care professionals make better decisions to reduce the risk of tree failure prior to the storm.

Using TRIZ to Invent Failures – Concept and Application to go Beyond Traditional FMEA

The Failure Mode and Effects Analysis (FMEA) is a very highly established methodology for preventing failures in technical systems [1] that developed over the last five decades. It became a standard tool, especially since the introduction to the automotive industry via the QS-9000.Despite of numerous successful applications the FMEA is limited to normal expectations of occurring failures (like the non-fulfilment of a function or small deviation from an expected value) [2]. The FMEA utilizes the breakdown structure for products or processes to identify single failure causes and effects.Usually the FMEA provides no consideration of interconnected failures and failure scenarios.There are a lot of good reasons for the usage of the FMEA: it is wide spread because of being a part of international standards and engineering education for a long time. To cover these drawbacks described above, additional tools for risk analysis and risk management can be used.The Anticipatory Failure Prediction as preventive component of the Anticipatory Failure Determination (AFD) is such a method that leads to a comprehensive set of failures and failure scenarios [3], [4].Additionally it provides procedures to “invent” possible failures in a structured but creative way [5]. Based on the analysis of both methods, ways to hybridize the methods are developed. This hybridization leads to the combination of the advantages of both methods (similar to the parallel execution of both methods), offers synergies, and expands the potential for industrial adoption by providing one elaborated tool. By using an application example the potential of the hybridized AFD-FMEA or so called Failure Mode and Effects Anticipation and Analysis (FMEAA) is pointed out.

Predicting Unknown Failures

For the prediction of failures of technical systems, a new method has been found which can be used in addition to the established methods FMEA and AFD. It is based on the idea of describing a system by means of a set of standard system parameters. The values of these are varied and the effects of the varied parameters are assessed. Since a failure as a faulty system state is one set of parameter values among others, it is expected to show up by their variation. This procedure does not require knowledge of the specific failure type.

USE OF ARTIFICIAL INTELLIGENCE TECHNIQUES FOR PROGNOSTICS: NEW APPLICATION OF ROUGH SETS

The objective of this paper is to set the context for the potential application of rough sets in prognostics. Prognostics is a field of engineering, which deals with predicting faults and failures in technical systems. Engineering solutions to respective problems embrace the use of multiple Artificial Intelligence (AI) techniques. The authors, first, review selected AI techniques used in prognostics and then propose the application of rough sets to build the system health prognostication model.

Microstructural Barriers against Fatigue Crack Growth

Fatigue induced fracture is the number one reason for failure of technical systems. However, in the stage of small crack growth grain or phase boundaries lead to a fluctuating crack propagation rate near the obstacle. Sometimes the cracks stop completely for a large number of cycles resulting in an additional number of life time cycles. However, so far it is not clear, what actually determines the resistance of a grain boundary against fatigue cracks. Therefore we developed a systematic experimental technique based on in-situ imaging in the scanning electron microscope and focused ion beam (FIB) crack initiation which gives detailed information on the interaction of short fatigue cracks with microstructural elements. We investigated the mechanisms of crack transmission in the neighbouring grain on the microscopic scale and identified different useful aspects of the interaction between microcracks and microstructural barriers. The 3D-tomographs revealed by serial sectioning an FIB give information about the transition process from one grain to the neighbouring one. The result is a purely geometrical consideration leading to a quantitative description of the blocking effect of grain boundaries on short fatigue crack growth. The results include useful aspects for fatigue life calculation and to make materials more fatigue resistant.

Analysis of the possibility of applying a condition-based maintenance model on an example of tank weapons

For any modern army it is very important to continuously maintain a high degree of operational (combat) readiness (availability) in order to maximize the effectiveness of the use of technical systems. Since determination and prediction of technical states and failures of technical systems in engineering, especially in armament, are difficult due to the impossibility of continuous condition monitoring with appropriate measuring equipment there is a need for a maintenance model that would be most helpful in taking timely action maintenance. In this paper, the subject of research is a model of maintenance of the M-84 tank weapoons systems. Introduction. The M-84 tank is one of the most promising technical systems in the Serbian Army. Its use and modifications are foreseen in the next ten years. The M-84 is characterized by good tactical and technical characteristics. It has a powerful 125 mm cannon, coupled 7.62 mm machine gun and 12.7 mm anti-aircraft machine gun. The M-84 tank has an automatic battery charger and a fire control system. The fire control system enables fast target tracking and stabilization of the cannon barrel, which is a prerequisite for timely and favorable effect on the target. There are certain ambiguities in the existing model of maintenance of tank weapons.

An enterprise risk management framework for evaluation of eMaintenance

Maintenance is one approach to managing risk by a reduction of the probability of failure of technical systems and/or the consequences of their failure. However, history has shown that erroneous maintenance also can lead to reduced quality, incidents and accidents with extensive losses. Today, eMaintenance promises great opportunities for a paradigm shift from a rather narrow, condition-based maintenance approach with focus on a technical system’s health to a true risk-based maintenance approach that also considers organizational excellence. This is achieved by proper information logistic solutions that address the needs of all stakeholders of the maintenance process, which are possible due to new and innovative information and communication technology (ICT). However, all opportunities are also linked with some threats, which are seldom highlighted in the case of eMaintenance. In this article, a risk management framework for evaluation of eMaintenance solutions is proposed. The framework is based on a combination of international standards (e.g. ISO 31000, ISO/IEC 27000, and IEC (2004) 60300-3-14) to achieve integrated Enterprise Risk Management (ERM) and enable a linkage of eMaintenance to the strategic goals of an organization. The framework is illustrated in the railway context of Trafikverket (2010b) (the Swedish Transport Administration).

Teaching the Air Midwest Case: A Stakeholder Approachto Deliberative Technical Rhetoric

What constitutes a cause is a particularly important question for those who teach or study technical writing. This article describes a case that helps students look beyond the technical "causes" of a commuter airplane crash in order to address the complex web of policies, practices, actions and events that contributed to the crash. Using an approach grounded in stakeholder theory and ethical theory, students use real documents ranging from news accounts to FAA policies to NTSB hearing exhibits to identify systemic problems that contributed to the disaster. Working from particular stakeholder perspectives, they work collaboratively to develop and argue for policy changes that will prevent future tragedies. The abundance of real documents that drive this case make it an especially useful tool for engaging students in difficult-to-teach subject matter including the role of writing in the failure of technical systems, deliberative and judicial rhetoric, stakeholder theory, visual rhetoric, and ethics.