Consecutive Failures Research Articles

Graph-logical models for (n, f, k) – and consecutive - k-out-of-n – systems

The article is devoted to methods of constructing graph-logical models of fault-tolerant multiprocessor systems. In particular, systems of the type (n, f, k), linear consecutive-k-out-of-n and circular consecutive-k-out-of-n are considered, which are characterized by the failure of the system when a certain number of consecutive processors fail. Graph-logical models can be used to estimate the reliability parameters of fault-tolerant multiprocessor systems by conducting statistical experiments with models of their behavior in the failure flow. The graph-logical models under construction are based on the basic models with a minimum of lost edges. It is determined that to build a graph-logical model of systems of this type, it is sufficient to calculate the maximum possible number of failed processors at which the system remains in operation. A graph-logical model of a basic system that can handle this number of failures is built, without taking into account the sequence of these failures. The next step is to identify all possible consecutive failures that cause the system to fail. Then, the base model is modified in such a way as to reflect the failure of the system when consecutive failures occur. This means weakening the base model on the previously determined vectors. The proposed methods of model construction can be used both for linear and circular consecutive-k-out-of-n systems and for (n, f, k) systems. A minor difference will be in the calculation of some parameters. The paper describes the calculation of such parameters as the maximum allowable number of failures at which the system remains in an operational state, as well as the calculation of the number of all combinations of consecutive failures at which the system fails. Experiments have been conducted to confirm the model's compliance with the system's behavior in the failure flow. Examples are given to demonstrate the process of building graph-logical models for linear consecutive-k-out-of-n, circular consecutive-k-out-of-n and (n, f, k) systems using the proposed methods.

The method of constructing a GL-model for a consecutive k-out-of-n system

The paper is devoted to the method of constructing GL-models of the behavior of multiprocessor systems in a failure flow, in particular, consecutive k-out-of-n systems are considered, whose main characteristic is the failure of the system when a certain number of processors connected consecutively fail. The GL-models under construction are based on the basic models with a minimum number of lost edges. It has been determined that to build a GL-model of systems of this type, it is sufficient to calculate the maximum possible number of failed processors at which the system remains operational. A GL-model of a system that can handle this number of failures is built without considering the consecutive failures. The next step is to determine all possible consecutive failures that cause the system to fail, and the model is modified to reflect the system failure when consecutive failures occur. The paper describes a method for calculating the maximum allowable number of failures at which the system remains operational. An example of building GL-models for consecutive k-out-of-n systems is given.

Vulnerability assessment and evolution analysis of Beijing's Urban Rail Transit Network

With the development of urban rail transit system, the complexity of the network intensifies, and its vulnerability shifts correspondingly. Understanding the characteristics and evolution of network vulnerability, as well as identifying developmental patterns, enables more scientific network planning. Current researches on network vulnerability predominantly focus on the static vulnerability assessment of existing networks, with limited studies on vulnerability evolution. This paper divides the topological evolution of the Beijing Urban Rail Transit Network (BURTN) from 2000 to 2020 into Formation and Improvement stages using the K-means++ method. By constructing a multidimensional vulnerability assessment model that considers node degree uniformity, network efficiency, and connectivity, the vulnerability evolution characteristics and patterns of BURTN are explored in cases of both Single-station failures and Multi-station consecutive failures (including random and intentional failures). Furthermore, the evolutionary relationship between network vulnerability and network structure is explored using the Ridge regression model. Calculations reveal that in the case of Single-station failures, during the Formation stage, the proportion of highly vulnerable stations (HVS) and the impact of each station failure on network performance decrease significantly, by 69.36 % and 67.67 %, respectively. During the Improvement stage, the proportion of HVS decreases significantly, while the impact of each station failure on network performance decreases slightly, by 79.10 % and 37.04 %, respectively. In the case of Multi-station consecutive failures, during the Formation stage, the network’s ability to cope with both random and intentional failures decreases, with the percentage of network nodes removed at the collapse state decreasing by 24.95 % and 11.12 %, respectively. During the Improvement stage, the network’s ability to cope with random failures remains stable, while its ability to cope with intentional failures decreases. This study helps to understand vulnerability from an evolutionary perspective and provides practical strategies for reducing vulnerability.

Cell motility in cancer, crucial events, criticality, and Lévy walks

The analysis of glioblastoma (GB) cell locomotion and its modeling inspired by Lévy random walks is presented herein. We study such walks occurring on a two-dimensional plane where the walk is similar to the motion of a bird flying with a constant velocity, but with random changes of direction in time. The intelligence of the bird is signaled by the instantaneous changes of flying direction, which become invisible in the time series obtained by projecting the 2D walk either on the x-axis or y-axis. We establish that the projected 1D time series share the statistical complexity of time series frequently used to monitor physiological processes, shedding light on the role of crucial events (CE-s) in pathophysiology. Such CE-s are signified by abrupt changes of flying direction which are invisible in the 1D physiological time series. We establish a connection between the complex scaling index δ generated by the CE-s through μR=2−δ, where μR is the inverse power law index of the probability density function of the time interval between consecutive failures of the process of interest. We argue that the identification of empirical indices along with their theoretical relations afford important measures to control cancer.

No Great Russia without Greater Russia

This paper argues that to understand the invasion of Ukraine, we need to have better insights into the Kremlin’s particular world view and Russia’s place within it. This view is based on a sense of entitlement to great power status, going hand in hand with an identity of itself as a country that extends beyond the actual borders of the Russian Federation. What makes the position unique is that the geopolitical and identity arguments are inseparable: in the Kremlin’s world view, Russia can only be a great power if it also exists as greater Russia. This structural factor is labelled the geopolitics-identity nexus. To explain why the invasion happened in 2022, three additional process factors are outlined: a radicalisation of the view of Ukraine as Russian lands, driven by the feeling of existential crisis when tensions over Ukraine escalated in 2014; an escalation of policy options resulting from consecutive failures in Russia’s Ukraine policy; and a reversal of the argument that Russia has to be a great power to exist within its 1991 borders into an argument that Russia has to expand its territory to be a great power.

Effects of Structural Bracing on the Progressive Collapse Occurrence

Statistics of human losses and financial casualties induced progressive collapse, as one of the new and modern concepts in the field of civil engineering, have doubled the importance of having knowledge about this phenomenon and strategies to reduce its effect. Progressive collapse starts with a local failure with loss of local load-carrying capacity of a small portion of the structure and spreads throughout the structure from element to element. These consecutive failures may cause the collapse of either the entire structure or a major part of it. This paper studies the effect of adding a bracing system to the steel moment frames designed for seismic loads through a nonlinear dynamic method according to GSA-2003 and UFC-4-023-03 criteria. The study was conducted using computational simulation of building models with two different elevations of three and six floors located in a moderate seismicity region. The simulation results showed higher resistance against the progressive collapse of the structure in the braced steel moment frames and less sensitivity to the removal of the column in the braced spans in comparison to the spans without bracing. The prediction of possible progressive collapse in the UFC-4-023-03 criterion is more conservative than the GSA-2003 criterion. Although, generally there is no significant difference between the analysis results of these two criteria.

Optimal Stopping Rules for Preventing Overloading of Multicomponent Systems

When random-strength components work as an interconnected parallel system, then its carrying capacity is random as well. In a case where such a multicomponent system is a subject of the stepwise-growing workload, some of its components fail and their loads are taken over by the ones that are intact. When the loading process is continued, the additional loads trigger consecutive failures that degrade the system, eventually leading to a complete failure. If the goal of the system is to carry as much load as possible, then the loading process should be continued, but no longer than until the loading capacity of the whole system is reached. On the other hand, with every additional load step, a failure of the system becomes more probable, as the carrying capacity is random and known solely through its probability distribution. In such cases, the decision on when to cease the loading process is not obvious. We introduce and analyse a minimal model of failure spreading in an array of progressively loaded pillars controlled by a decision-maker who stops the process when a required load is attained. We show how to construct an optimal stopping rule. Under some additional assumptions regarding the adopted loss function, it is argued that the optimal stopping rule is of the threshold type and it significantly depends on the shape of the load-step probability distribution.

Modelling of cantilever bank failure for peat-type meander bends in the source region of the Yellow River

Bank retreat involving a combination of fluvial erosion and bank collapse has been found to be a major contributor to sediment transport, lateral migration, and planform evolution of meandering rivers. Previous studies have largely examined the general mechanism of cantilever bank failure. However, the composite process of beam (toppling) failure caused by shear failure of the lower part composed of non-cohesive soil remains poorly understood. The current paper investigates the diversity and coupling of this collapse process, which is the dominant pattern in the peat-type meandering rivers of the Zoige River basin in the source region of the Yellow River. For this purpose, morphologic and hydraulic measurements were done in the summers of 2016 and 2017. Moreover, a combined method of a theoretical model and numerical simulation was developed to be applied for a continuous meandering channel in the Zoige basin, focusing in particular on five typical cross sections of a highly convoluted bend approaching neck cutoff. Specifically, the theoretical model evaluating the stability of overhanging riverbank was based on static equilibrium theory considering the interaction between composite soil layers. In addition, the Bank Stability and Toe Erosion Model was used to simulate the retreat process of the silt layer based on field measurements including bank morphology, soil composition, and hydrological parameters. Thus, a calculation method for the occurrence of cantilever beam failure in the flood period is proposed, and temporal change and spatial variability in bank profiles caused by three consecutive failures is estimated at the five sections. Satisfactory results showed a relatively close agreement between the calculations and field measurements in terms of the width of the overhanging arms and the dimensions of the slump blocks.

Use of exponential distribution in mathematical models of dependability

The exponential distribution of time to event or end of state is popular in the dependability theory. This distribution is characterized by the strength that is a convenient parameter used in mathematical models and calculations. The exponential distribution is used as part of dependability-related process simulation. Examples are given to illustrate the applicability of the exponential distribution. Aim. The aim of the paper is to improve the dependability-related simulation methods when using the exponential distribution of periods of states or times to events. Methods. The assumption of the exponential distribution of time between events can be justified or discarded using methods of the probability theory and/or mathematical statistics or on the basis of personal or engineering experience. It has been experimentally established that the failure flow in an established mode of operation is stationary, ordinary and produces no consequences. Such flow is Poisson and is distinct in the fact that the time between two consecutive failures is distributed exponentially with a constant rate. This exponential distribution is reasonably extended to the distribution of an item’s failure-free time. However, in other cases, the use of exponential distribution is often not duly substantiated. The methodological approach and the respective conclusions are case-based. A number of experience-based cases are given to show the non-applicability of exponential distribution. Discussion. Cases are examined, in which the judgement on the applicability or non-applicability of exponential distribution can be made on the basis of personal experience or the probability theory. However, in case of such events as completion of recovery, duration of scheduled inspection, duration of maintenance, etc., a judgement regarding the applicability of exponential distribution cannot be made in the absence of personal experience associated with such events. The distribution of such durations is to be established using statistical methods. The paper refers to the author’s publications that compare the frequency of equipment inspections with regular and exponentially distributed periods. The calculated values of some indicators are retained, while for some others they are different. There is a two-fold difference between the unavailability values for the above ways of defining the inspection frequency. Findings and conclusions. The proposed improvements to the application of exponential distribution as part of dependability simulation come down to the requirement of clear substantiation of the application of exponential distribution of time between events using methods of the probability theory and mathematical statistics. An unknown random distribution cannot be replaced with an exponential distribution without a valid substantiation. Replacing a random time in a subset of states with a random exponentially distributed time with a constant rate should be done with an error calculation.

Online condition monitoring algorithm for element failure detection and fault location in double wye shunt capacitor banks

Failure in quick detection and location of internal failures in Shunt Capacitor Banks (SCBs) may lead to the negligence of necessary repair processes, consequently laying undesirable effects on the power system operation. This paper puts forward a failure detection and fault location method in SCBs with the double wye connection. The proposed method provides a criterion for relay decision-making based on the neutral voltage and current fundamental phasor component, capable of distinguishing the faulty capacitors and determining the number of capacitor failures in the case of multiple faulty phases. The proposed algorithm can be applied for double wye SCBs considering different protection designs, namely fuseless and internally fused units. The proposed method is designed to monitor and detect consecutive failures based on the existing data from commercial relays. Implementation and performance evaluations are conducted in PSCAD and MATLAB software and also with the help of practical data. Performance evaluations are conducted under different circumstances, namely harmonic distortion and voltage unbalance conditions, multiple internal fault locations, and external faults from the grid. Simulation results show the significance and salient features of the proposed method under different conditions.

Famines and likelihood of consecutive megadroughts in India

Consecutive failures in the summer monsoon rainfall led to widespread and severe droughts with profound implications for agricultural activities in India. However, the likelihood of successive megadroughts in India’s past and future climate remain poorly understood. Using Palmer Drought Severity Index (PDSI) from the Monsoon Asia Drought Atlas (MADA), we show that the major famines that affected millions of people during 1200–2018 were linked with summer monsoon droughts. Four megadroughts covering more than 40% of the country occurred for two consecutive summer monsoon seasons during 1200–2018. The most recent and severe megadrought occurred in 2002–2003. Simulations from the Community Earth System Model (CESM) for the last millennium (850–2005) ensemble (LME) show that the likelihood of two and three-year consecutive megadroughts during the summer monsoon is about 0.7 and 0.3 events per 100 years, respectively. Large ensemble simulations from CESM (CESM-LE) show a decline in the frequency of megadroughts in the future. Summer monsoon megadroughts are strongly associated with the warm sea surface temperature (SST) anomalies over the Pacific Ocean in the past and future climate. Substantial warming under the projected future climate can cause megadroughts under near-normal precipitation during the summer monsoon season. Despite the projected decline in the likelihood of the summer monsoon megadroughts under the warming climate, megadroughts in the future can have considerable implications for India’s food production and water availability.

P–575 Patients with recurrent implantation failures (RIF): chromosome abnormalities in the resulting embryos

Abstract Study question Do RIF patients have the preimplantation genetic testing for aneuploidy (PGT-A) overcome their infertility condition? Summary answer PGT-A positively impact on implantation rate in RIF patients What is known already The most common definition of RIF is failure to achieve a pregnancy after three consecutive transfers of good quality embryos. This term possibly represents a heterogeneous category of infertile couples as the causes of repeated failures can be diverse. Especially intriguing is the case of patients with an age lower than 39 years for which the oocyte quality is expected not to be compromised by the well known age effect on female fertility. The chromosome analysis of the resulting embryos has been proposed as a valid method to improve implantation in the great majority of RIF patients Study design, size, duration This retrospective study included 49 patients with at least three previous consecutive implantation failures, which underwent PGT-A from January 2016 to April 2020. Both partners had a normal karyotype. Only patients with a female age below 39 years were included, who presented with a normal uterine cavity. Couples with a severe male factor were excluded. Single frozen blastocysts were transferred according to chromosomal results Participants/materials, setting, methods Maternal age was 35.5 ± 3.1 years. All blastocysts were vitrified after trophectoderm biopsy. Whole genome amplification and array comparative genomic hybridization were performed on biopsies. Only euploid embryos were transferred. The primary outcome was the live-birth delivery rate after the first transfer Main results and the role of chance Before starting a PGT-A cycle, these patients underwent 213 embryo transfers with 251 embryos replaced. A total of 264 blastocysts were analyzed, 140 of which were aneuploid (53%). Monosomy or trisomy was reported in 67 of the diagnosed samples (67/140, 48%) whereas the remaining 73 carried complex aneuploidies (73/140, 52%). The remaining 124 blastocysts (47%) were diagnosed as euploid. All patients performed an embryo transfer resulting in 28 clinical pregnancies (57%). There were 5 spontaneous abortions and the live-birth delivery rate per patient was 47% Limitations, reasons for caution This study suffers from the weakness related to retrospectivity. In addition, as euploid embryos are still cryopreserved, the delivery rate could change at completion of the cycles Wider implications of the findings: A RIF condition can be attributed, at least in a good proportion of cases, to the generation of high percentages of aneuploid embryos. In this case, the transfer of euploid blastocysts has high chances to classify this category of RIF patients has having an embryonic cause of infertilit. Trial registration number Not applicable

PPOS Protocol Effectively Improves the IVF Outcome Without Increasing the Recurrence Rate in Early Endometrioid Endometrial Cancer and Atypical Endometrial Hyperplasia Patients After Fertility Preserving Treatment.

Objective: To investigate the effectiveness and recurrence risk of different ovulation stimulation protocols in early-stage endometrioid endometrial cancer (EEC) and atypical endometrial hyperplasia (AEH) patients after successful fertility preserving treatment.Design: A retrospective review of clinical files between June 2012 and July 2018.Setting: University hospital.Patients: Ninety seven women (74 AEH and 23 early-stage EEC patients) underwent in vitro fertilization (IVF) and frozen-thawed embryo transfer (FET) after successful fertility preserving treatment. All patients received megestrol acetate which was initiated immediately after AEH or EEC diagnosis by hysteroscopy. Fertility treatment was initiated after confirmation of complete response by two consecutive hysteroscopic evaluations and endometrium biopsy in a 3-month interval. Women with tubal factors underwent IVF treatment directly. Women who failed to conceive spontaneously within 12 months or after other infertility treatments like ovulation induction for 6 consecutive months or 2 consecutive artificial insemination failures were also offered IVF treatment.Main Outcome Measure (s): The clinical and laboratory embryo data, clinical pregnancy outcomes and endometrial disease recurrence rates.Results: Compared with the standard regimen group, the good-quality embryo rate was higher in progestin primed ovarian stimulation (PPOS) regimen group (P = 0.034). Univariate analysis showed significant differences in age (P = 0.033), treatment time of endometrial lesions (P < 0.001), and duration of Gn treatment (P = 0.018) between the recurrent and non-recurrent groups. In the adjusted model of multivariate logistic regression analysis, the age (P = 0.014) at ovulation induction and treatment time of endometrial lesions (P < 0.001) were significantly correlated with the recurrence of endometrial disease.Conclusions: The PPOS protocol is a feasible and safe strategy to stimulate ovulation during IVF after fertility preservation therapy, and the age at ovulation induction and treatment time of endometrial lesions are two stable predictors of recurrence in endometrial diseases.

Uncertainty in the Hot Hand Fallacy: Detecting Streaky Alternatives to Random Bernoulli Sequences

AbstractWe study a class of permutation tests of the randomness of a collection of Bernoulli sequences and their application to analyses of the human tendency to perceive streaks of consecutive successes as overly representative of positive dependence—the hot hand fallacy. In particular, we study permutation tests of the null hypothesis of randomness (i.e. that trials are i.i.d.) based on test statistics that compare the proportion of successes that directly follow $k$ consecutive successes with either the overall proportion of successes or the proportion of successes that directly follow $k$ consecutive failures. We characterize the asymptotic distributions of these test statistics and their permutation distributions under randomness, under a set of general stationary processes, and under a class of Markov chain alternatives, which allow us to derive their local asymptotic power. The results are applied to evaluate the empirical support for the hot hand fallacy provided by four controlled basketball shooting experiments. We establish that substantially larger data sets are required to derive an informative measurement of the deviation from randomness in basketball shooting. In one experiment, for which we were able to obtain data, multiple testing procedures reveal that one shooter exhibits a shooting pattern significantly inconsistent with randomness—supplying strong evidence that basketball shooting is not random for all shooters all of the time. However, we find that the evidence against randomness in this experiment is limited to this shooter. Our results provide a mathematical and statistical foundation for the design and validation of experiments that directly compare deviations from randomness with human beliefs about deviations from randomness and thereby constitute a direct test of the hot hand fallacy.

Second redo surgery after two consecutive failures of a colorectal or coloanal anastomosis: is it reasonable?

Colorectal redo surgery is well known to be a difficult procedure, associated with a high risk of failure. The aim of this study was to look into patients presenting two consecutive failed colorectal (CRA) or coloanal (CAA) anastomosis who underwent a second redo surgery (i.e., third anastomosis). A retrospective study based on a prospective database of second redo surgeries of CRA or CAA, in an expert center. Sixteen patients between 2005 and 2020 were analyzed. After a mean follow-up of 28 ± 26months, success of surgery (defined as no stoma at the end of follow-up) was reported in 10/16 patients (63%). One patient with chronic anastomotic leakage and another with early colonic ischemia had no defunctioning stoma reversal. In the remaining four patients with a failed second redo surgery, a definitive stoma was ultimately created for fistula recurrence (n = 1), poor functional results (n = 2), or local cancer recurrence (n = 1). Two risk factors for failure of this second redo surgery were significantly found in a univariate analysis: (1) nature of the primary anastomosis: 3/13s redo surgeries failed (23%) if a CRA was first made and 3/3 (100%) if it was a CAA (p = 0.036); (2) age: patients with a failed second redo surgery were older (p = 0.04). A 63% rate of success of second redo surgery was observed after two failed CRA or CAA. Although a demanding procedure, it can be proposed to carefully selected and motivated patients.

Optimal Transmission Line Switching to Improve the Reliability of the Power System Considering AC Power Flows

The reliability of the electrical system is a fundamental study that is carried out to determine the possible deficiencies that an electrical system can have in case of failures, since a failure can cause disturbances, power cuts, and load disconnections. For this reason, Optimal Transmission Switching (OTS) with Optimal AC Power Flows (OPF-AC) is used to reduce disturbances when faults occur and minimize equipment load and disconnections, but OTS offers possible switches in order to make it possible to reduce the damage that can be done for a fault with operating limitations in voltage, power, and angular deviation. However, to have a complete study, it is proposed to use a reliability analysis through contingency ranking to know the risks that a switched system may have at the time of simultaneous or consecutive failures. In addition, a load capacity investigation is conducted to determine if the transmission lines are within their operating limits. The study presents an analysis of the behavior of the switched system and an adequate operation for the mitigation of failures in the system through the switching of transmission lines with analysis of load capacity and reliability. The results presented by the proposed methodology will be compared with Matlab’s Matpower simulation package.

Chromeno[3,4-b]xanthones as First-in-Class AChE and Aβ Aggregation Dual-Inhibitors

Alzheimer’s disease (AD) is a complex multifactorial disorder, mainly characterized by the progressive loss of memory and cognitive, motor, and functional capacity. The absence of effective therapies available for AD alongside the consecutive failures in the central nervous system (CNS) drug development has been motivating the search for new disease-modifying therapeutic strategies for this disease. To address this issue, the multitarget directed ligands (MTDLs) are emerging as a therapeutic alternative to target the multiple AD-related factors. Following this concept, herein we describe the design, synthesis, and biological evaluation of a family of chromeno[3,4-b]xanthones as well as their (E)-2-[2-(propargyloxy)styryl]chromone precursors, as first-in-class acetylcholinesterase (AChE) and β-amyloid (Aβ) aggregation dual-inhibitors. Compounds 4b and 10 emerged as well-balanced dual-target inhibitors, with IC50 values of 3.9 and 2.9 μM for AChE and inhibitory percentages of 70 and 66% for Aβ aggregation, respectively. The molecular docking showed that most of the compounds bound to AChE through hydrogen bonds with residues of the catalytic triad and π-stacking interactions between the main scaffold and the aromatic residues present in the binding pocket. The interesting well-balanced activities of these compounds makes them interesting templates for the development of new multitarget compounds for AD.

Reliability Estimation under Scarcity of Data: A Comparison of Three Approaches

During the last decades, the optimization of the maintenance plan in process plants has lured the attention of many researchers due to its vital role in assuring the safety of operations. Within the process of scheduling maintenance activities, one of the most significant challenges is estimating the reliability of the involved systems, especially in case of data scarcity. Overestimating the average time between two consecutive failures of an individual component could compromise safety, while an underestimate leads to an increase of operational costs. Thus, a reliable tool able to determine the parameters of failure modelling with high accuracy when few data are available would be welcome. For this purpose, this paper aims at comparing the implementation of three practical estimation frameworks in case of sparse data to point out the most efficient approach. Hierarchical Bayesian modelling (HBM), maximum likelihood estimation (MLE), and least square estimation (LSE) are applied on data generated by a simulated stochastic process of a natural gas regulating and metering station (NGRMS), which was adopted as a case of study. The results identify the Bayesian methodology as the most accurate for predicting the failure rate of the considered devices, especially for the equipment characterized by less data available. The outcomes of this research will assist maintenance engineers and asset managers in choosing the optimal approach to conduct reliability analysis either when sufficient data or limited data are observed.

ЗАБЕЗПЕЧЕННЯ КІБЕРБЕЗПЕКИ АСУ ТП ШЛЯХОМ ЗАСТОСУВАННЯ ПЛІС-ТЕХНОЛОГІЇ

In modern conditions, cybersecurity issues are moving from the level of information protection at a separate object of computer technology to the level of creating a single cybersecurity system of the state, as part of the information and national security system responsible for protecting not only information in the narrow sense, but also all cyberspace. In the process of forming global cyberspace, military and civilian computer technologies are converging, new means and methods of influencing the information infrastructure of a potential adversary are being developed, and specialized cyber centers are being created and implemented on high-tech platforms. At present, the cybersecurity procedure does not fully reflect the issues related to the cybersecurity of the ACS TP. This is due to the fact that the ACS PA was originally developed based on the ideology of physical isolation from external networks and strict delimitation of access by service personnel, using specific software, information exchange via industrial communication protocols Modbus, Profibus, etc., which often work on top of the TCP / IP protocol. Accordingly, there are many vulnerabilities in the ACS TP, the probability of which in various cyber incidents is directly proportional to the importance and significance of the object. Given the fact that the ACS TP have become an integral part of our existence, respectively, the problem of cybersecurity of the systems under consideration is today an urgent and timely task. The article discusses an approach to ensuring the cybersecurity of automated process control systems (APCS) by creating intelligent cybersecurity systems (ISCs). It is assumed that the construction of the proposed systems should be based on the concept of "evolution (development)", that is, the ability of the system to adapt through changes in parameters under the influence of external and internal cyber threats (cyber attacks), through the applied technologies, to counter cyber attacks throughout the entire life cycle. Technically, it is proposed to implement the ISCs by means of using an expert system and disaster-tolerant information systems (DIS), a characteristic feature of which, in contrast to fault-tolerant systems, is the continuation of work in conditions of massive and, possibly, consecutive failures of the system or its subsystems as a result of cyberattacks. These properties (catastrophic properties – system survivability) are possessed by programmed logic integrated circuits (FPGA) – a class of microprocessor systems, a characteristic feature of which is the ability to implement a multiprocessor (parallelized) structure that can withstand external influences (cyber attacks). By themselves, FPGA are an integrated circuit, the internal configuration of which is set by programming using special languages for describing hardware

A bivariate two-state Markov modulated Poisson process for failure modeling

Motivated by a real failure dataset in a two-dimensional context, this paper presents an extension of the Markov modulated Poisson process (MMPP) to two dimensions. The one-dimensional MMPP has been proposed for the modeling of dependent and non-exponential inter-failure times (in contexts as queuing, risk or reliability, among others). The novel two-dimensional MMPP allows for dependence between the two sequences of inter-failure times, while at the same time preserves the MMPP properties, marginally. The generalization is based on the Marshall–Olkin exponential distribution. Inference is undertaken for the new model through a method combining a matching moments approach with an Approximate Bayesian Computation (ABC) algorithm. The performance of the method is shown on simulated and real datasets representing times and distances covered between consecutive failures in a public transport company. For the real dataset, some quantities of importance associated with the reliability of the system are estimated as the probabilities and expected number of failures at different times and distances covered by trains until the occurrence of a failure.