Ing. Martin Daňhel, Ph.D.

Stať ve sborníku

10.1109/MECO.2017.7977177

Katedra číslicového návrhu

This paper describes evaluation and consequent improvements in the field of dependability prediction from the beginning to nowadays. The necessity to determine the reliability characteristics of the electronic equipments is shown. The basic terms, definitions, and current problems are described. The demonstration of the prediction of reliability parameters according to the MIL-HDBK-217 standard based studies is presented by case studies - real examples from Czech railways track circuits projects and the discussion of the results of student tasks.

Stať ve sborníku

10.1109/QRS.2017.43

Katedra číslicového návrhu
Katedra aplikované matematiky

In the presented work we predict the life expectancy of multi-part railway fail-safe signaling systems. The monitored electronic track circuits detect train locations and movement in real time, and issue alerts and warnings to prevent collisions. Based on 10 years of failure reports from the manufacturer of systems used by Czech railroads, we establish estimates of time-to-failure distributions of their components. We modify and apply survival models for censored data with various parameters for which we propose and compare new estimators. Both left and right time-based censoring of the data is considered. This approach allows us to include in the analysis components that were in operation before the study started, as well as components that were functional after the end of the study. Special attention is paid to the correct treatment of missing and incomplete data in the analyzed reports. We compare models with constant and variable failure rates. Hypotheses testing methodology is used to select a model with the best fit for the analyzed data.

Článek

10.1016/j.micpro.2017.05.004

Katedra číslicového návrhu

Markov chain models are used to evaluate the dependability properties (reliability, safety, availability, maintainability etc.) of the mission-critical systems. Dependability models are often focused only on the basic stuck-at faults. On the other hand the transient faults are present in the operational environment but not included in the dependability prediction. The aim of this paper is to show how the transient faults influence the dependability prediction using the Markov chain model. In this paper basic TMR Markov chain model using stuck-at faults is compared to our extended TMR model considering both the stuck-at and transient faults. The main focus is given on the calculation of the dependability parameter lambda (i.e. the failure rate of the system).

Stať ve sborníku

Katedra číslicového návrhu

Markov chain models are used to evaluate the dependability properties (reliability, safety, availability, maintainability etc.) of the systems especially those used in mission-critical applications. Based on these models the fault intensity and operational time length of such systems can be predicted. But in most cases these models are derived only by basic stuck-at fault models. The main aim of this paper is to compare the basic TMR (Triple-Modular-Redundancy) Markov chain model using the stuck-at faults only with TMR considering both per manent and transient faults. The main focus is given on the calculation of the dependability parameters. Obtained results are compared and discussed.

Stať ve sborníku

Katedra číslicového návrhu

To evaluate the dependability properties of mission-critical systems like reliability, safety, availability, maintainability etc. a Markov chain models can be used. However the dependability prediction using these models is focused only on the stuck-at faults even though the system is exposed to the influence of transient faults produced by the operational environment. It is the aim of this paper to show how the transient faults influence the dependability prediction -- e.g., the calculation of the dependability parameter lambda (the failure rate of the system). A basic TMR (Triple Modular Redundancy) Markov chain model using stuck-at faults is compared to our extended TMR model considering both the stuck-at and transient fault.

Stať ve sborníku

10.1109/DSD.2016.73

Katedra číslicového návrhu

Markov chain models are used to evaluate the dependability properties (reliability, safety, availability, maintainability etc.) of the mission-critical systems. Dependability models are often focused only on the basic stuck-at faults. On the other hand the transient faults are present in the operational environment but not included in the dependability prediction. The aim of this paper is to show how the transient faults influence the dependability prediction using the Markov chain model. In this paper basic TMR Markov chain model using stuck-at faults is compared to our extended TMR model considering both the stuck-at and transient faults. The main focus is given on the calculation of the dependability parameter lambda (i.e. the failure rate of the system).

Stať ve sborníku

Katedra číslicového návrhu

The article describes comparing the most common methods of reliability prediction with the real operational reliability. The mentioned methods are used from the generally accepted military standard MIL-HDBK 217F. This standard describes two methods: Stress Parts and Parts Count that are built against measured data from real operation. Reliability prediction and operational reliability are calculated on a railway signaling equipment that complies with safety requirements of the highest safety integrity level SIL = 4. In conclusion, the article are discussed the advantages and disadvantages of each approaches. This article aims to show what results can provide reliability standards and what may be the fact.

Stať ve sborníku

10.1109/DSD.2013.66

Katedra číslicového návrhu

This paper describes the analysis of dependability and predictive reliability. The proposed methodology is based on hierarchical models and the generally acclaimed standard MIL-HDBK-217F. The equipment is a real component of the railway interlocking system in Czech Republic. The equipment is designed for high dependability and with respect of disturbances caused by the near environment. A possible encapsulation using UML to model processes affecting the reliability is shown.

Stať ve sborníku

Katedra číslicového návrhu

Článek popisuje metodiku pro analýzu a predikci spolehlivosti. Navrhovaná metodika je založena na hierarchických modelech a vychází z normy MIL-HDBK-21F. Popisovaná metodika se uplatní zejména při analýze spolehlivosti drážních zabezpečovacích zařízení, kde se předpokládá jisté bezpečnostní doporučení upravené normou EN CSN 50126. Dále j nastíněno využití hierarchických modelů pro modelování se zálohou a využití provozní databáze spolehlivosti. V závěru je naznačen směr, kterým by se měla ubírat dizertační práce zabývající se právě garantovanou úrovní spolehlivosti a bezpečnosti.

Stať ve sborníku

Katedra číslicového návrhu

Článek popisuje metodiku pro analýzu a predikci spolehlivosti. Navrhovaná metodika je založena na hierarchických modelech a vychází z normy MIL-HDBK-217F. Popisovaná metodika se uplatní zejména při analýze spolehlivosti drážních zabezpečovacích zařízení, kde se předpokládá jisté bezpečnostní doporučení upravené normou EN CSN 50126. Dále je nastíněno využití hierarchických modelů pro modelování se zálohou a využití provozní databáze spolehlivosti. V závěru je naznačen směr, kterým by se měla ubírat dizertační práce zabývající se právě garantovanou úrovní spolehlivosti a bezpečnosti.

Stať ve sborníku

Katedra číslicového návrhu

This paper describes a new approach to reliability models, namely hierarchical block reliability. It describes the idea of combining different models of reliability using Reliability Block Diagrams. The basic idea is the level of abstraction, where the user can imagine a large block model as a separate block. These blocks can be nested as well as other reliability models ofr example Markov chains. To work with there models program called SHAMAP was developed that performs mathematical calculations in the system Maple.

Stať ve sborníku

Katedra číslicového návrhu

Článek pojednává o hierarchických spolehlivostních modelech, založených na blokových spolehlivostních modelech. Je popsána metodika návrhu hierarchických blokových modelů. Současně je představen program SHAMAP, který se vyvíjí podle dané metodiky. Hierarchické modely dokáží zjednodušovat návrh, protože je lze vzájemně vnořovat. Do bloků lze vnořovat i jiné spolehlivostní modely.

Stať ve sborníku

Katedra číslicového návrhu

The article discusses the reliability of hierarchical models, based on reliability block models. It describes the design methodology of hierarchical block models. At the same time introduced a program SHAMAP, which evolves according to the methodology. Hierarchical models can simplify the design, because they can be mutually nested. The blocks can be nested and different reliability models.