scholarly journals Consistency Checking of the IEC 61508 PFH Formulas and New Formulas Proposal Based on the Markovian Approach

2021 ◽  
Vol 54 (6) ◽  
pp. 871-879
Author(s):  
Hanane Omeiri ◽  
Fares Innal ◽  
Yiliu Liu
Keyword(s):  
Failure Probability ◽  
Performance Indicators ◽  
Point Of View ◽  
Consistency Checking ◽  
Failure Frequency ◽  
Iec 61508 ◽  
Markovian Approach

Safety Instrumented Systems (SISs) are of prime importance in protecting people, assets and environment from hazardous events. Therefore, it is important to be able to assess accurately their performance indicators. For this end, IEC 61508 standard has provided two reliability metrics: the average failure probability of a SIS lowly demanded (PFDavg) and the average failure frequency of a SIS highly or continuously demanded (PFH). The aim of this paper is to investigate the IEC 61508 PFH formulas and to propose new ones based on the Markovian approach. Indeed, the new edition of IEC 61508 provides PFH formulas reflecting the possibility of automatic shutdown of the monitored process upon detection of a dangerous failure in the SIS. However, the IEC 61508 attempt remains incomplete and provide non-conservative results, which is dangerous from a safety point of view.

EFFECTIVENESS OF MANAGEMENT IN THE HIGHER EDUCATION

2021 ◽  
Vol 4 (48) ◽  
pp. 5
Author(s):  
O. Vorobyova
Keyword(s):  
Higher Education ◽  
Empirical Research ◽  
Performance Indicators ◽  
Point Of View ◽  
Educational Services ◽  
Management Effectiveness ◽  
Higher Education Management ◽  
Education Management ◽  
Management Efficiency ◽  
Theoretical Approaches

The article presents the results of empirical research of the main theoretical approaches to the concept of efficiency of management services in the field of higher education. It is determined that the concept of efficiency management is a complex multifaceted indicator that includes certain performance indicators related to efficiency, profitability, effectiveness, etc., in economics and management there is no single general approach to determining the effectiveness of management. It is proved that the effectiveness of management is a complex indicator that determines the use of resource opportunities to achieve a certain goal, and these concepts are complementary and interrelated, this approach from the point of view of economics is integrated with all management functions.Ключові слова: higher education; management efficiency; management effectiveness; management efficiency in higher education; educational services.

The Efficiency Of Higher Education Institutions: Evaluation And Management Of Managers

2021 ◽  
Vol 38 (4) ◽  
Author(s):  
Olesia Tomchuk ◽  
Viktoriia Tserklevych ◽  
Olena Hurman ◽  
Valentin Petrenko ◽  
Kateryna Chymosh
Keyword(s):  
Higher Education ◽  
Performance Indicators ◽  
Higher Education Institutions ◽  
Key Performance Indicators ◽  
Point Of View ◽  
Teaching Staff ◽  
University Professors ◽  
Business Entities ◽  
Management Functions ◽  
The University

The article discusses the potential opportunities for leaders of higher education to monitor and implement development management functions using a system of key performance indicators, which is often used by various business entities. The authors adapted it to the needs of higher education institutions, integrating them with their characteristics.The formation of a system of key performance indicators in the article is disclosed from the point of view of improving the management system and motivation of the management and teaching staff of higher education. Approbation of the proposed methodology was implemented in the Institution of Higher Education, where it showed its effectiveness. The new system allowed the university professors to influence directly on the bonus part of income through their own work and efficiency.

scholarly journals MARSplines method as a tool for failure frequency modelling

2018 ◽  
Vol 44 ◽  
pp. 00086
Author(s):  
Małgorzata Kutyłowska
Keyword(s):  
Linear Regression ◽  
Multiple Linear Regression ◽  
Failure Rate ◽  
Basis Function ◽  
Adaptive Algorithm ◽  
Point Of View ◽  
Water Utility ◽  
Failure Frequency ◽  
Rate Prediction ◽  
Operational Data

The paper presents the results of failure rate prediction using adaptive algorithm MARSplines. This method could be defined as segmental and multiple linear regression. The range of segments defines the range of applicability of that methodology. On the basis of operational data received from Water Utility two separate models were created for distribution pipes and house connections. The calculations were carried out in the programme Statistica 13.1. Maximal number of basis function was equalled to 30; so-called pruning was used. Interaction level equalled to 1, the penalty for adding basis function amounted to 2, and the threshold – 0.0005. GCV error equalled to 0.0018 and 0.0253 as well as 0.0738 and 0.1058 for distribution pipes and house connections in learning and prognosis process, respectively. The prediction results in validation step were not satisfactory in relation to distribution pipes, because constant value of failure rate was observed. Concerning house connections, the forecasting was slightly better, but still the overestimation seems to be unacceptable from engineering point of view.

Application of Hydropower Unit Governor Islanding Control Methods in the Xiaowan Direct Current Island System

2012 ◽  
Vol 212-213 ◽  
pp. 1034-1042
Author(s):  
Xiao Feng Cai ◽  
Hong Tao Zhang ◽  
Hong Rong ◽  
Cheng Bin Lio ◽  
Xiang Zhu ◽  
...  
Keyword(s):  
Direct Current ◽  
Performance Indicators ◽  
Control Algorithm ◽  
Point Of View ◽  
Control Mode ◽  
Speed Governor ◽  
Unit Speed ◽  
Analysis Of Results ◽  
Island System ◽  
Speed Adjustment

This paper, starting from the professional point of view of turbine governor and according to various data in the test, presents a preliminary analysis of results in combination of various tests competed after Xiaowan Power Station 700MW hydropower unit speed governor was put into island mode operation after the Chu Hui direct current line was off-stream (trial). Meanwhile, it describes the adjustment that the speed control system should make once the power system is in the island mode, including the conversion of the control mode, the switch of control parameter and optimization of control algorithm, focuses on analyzing the optimization of control strategy of the speed governor in the island mode, and discusses the active and speed adjustment method of the units and the associated performance indicators.

An Aging Simulation Model for the Emergency Diesel Generators of Angra 2 by Supplementary Variables

2008 ◽  
Author(s):  
Iona´ Maghali Santos de Oliveira ◽  
Paulo Fernando Ferreira Frutuoso e Melo ◽  
Marcos Oliveira de Pinho
Keyword(s):  
Nuclear Power ◽  
Power Plants ◽  
Point Of View ◽  
Failure Rates ◽  
Aging Effects ◽  
Supplementary Variables ◽  
Technical Specifications ◽  
Diesel Generators ◽  
Markovian Approach ◽  
Useful Lifetime

The extension of the useful lifetime of nuclear power plants is an issue of great importance and concern. From the reliability point of view, this problem requires the consideration of time-dependent failure rates and possible failure dependencies. This analysis has been typically performed through a Markovian approach. To illustrate this point, we have developed a computerized reliability analysis of the emergency diesel generators (EDGs) of a four “loop” PWR plant, considering the hypothesis of aging and perfect repair by using Supplementary Variables to cast the initially Nonmarkovian model into a Markovian one. In order to perform such analysis and to simulate aging effects, a nuclear plant has been taken for reference, which has been commercially operating for only six years. Failure rates were obtained from similar EDGs of another plant, already under aging, while repair data were taken from its technical specifications. Discontinuous repair rates were considered in order to improve maintenance strategies. Several ages were attributed to these equipments, allowing the calculus of the failure probability as well as their availability according to each regarded age. In this sense, the EDGs behavior as to aging can be obtained in detail and decisions concerning maintenance and useful lifetime extension can be made on a stronger basis. To get the desired results in terms of reliability figures and due to the discontinuous repair rates that had to be taken into account, a new numerical method that uses a part of the analytical solution, called Euler Iterative + Characteristic, has been developed in order to solve the differential equations systems, making the solving of the system faster and more efficient.

scholarly journals Overheads as a Performance Indicator in the Local Public Sector Organizations

2020 ◽  
Vol 15 (8) ◽  
pp. 1
Author(s):  
Christian Rainero ◽  
Alessandro Migliavacca ◽  
Sara Reano
Keyword(s):  
Public Sector ◽  
Performance Indicators ◽  
Performance Indicator ◽  
The United States ◽  
Point Of View ◽  
Direct Access ◽  
Capital Investments ◽  
Public Companies ◽  
Non Profit ◽  
Real Market

If we consider business forms from the point of view of satisfying needs, public companies are consumer companies that satisfy collective needs with the aim of redistributing income. They differ from production companies in that they do not have direct access to the market, so that the sources of financing derive from the taxes imposed by law, while the uses concern management costs, capital investments and debt repayments. Maintaining this interpretation, another category belonging to consumer companies is that of non-profit companies, which can be equated partially to public companies precisely because of the absence of a real market of reference and the finding of sources of funding for the performance of the activity mainly from external contributions without consideration. The only difference is inherent in the fact that such contributions cannot be imposed by law and are aimed at assisting and providing services and benefits to the community of reference, in the absence of profit and capital distribution. Therefore, if in the public sector performance is mainly and historically linked to the management of financial resources and public debt, in the field of nonprofit there is a different literature focused more on the control of economic aspects (and in particular the costs of the activity) as performance indicators of the company's activity. At the international level, and in particular in the United States, the use of the incidence of overheads is an element of examination to assess the performance of the non-profit sector. In this article, the subject of analysis is the possibility of using the overhead level to assess the performance of a public body. The analysis is carried out by comparing the incidence of overheads on the revenues of Italian municipalities in the years 2015-2017 with the performance indicators given by the deficit parameters established by current administrative legislation. From this analysis, it is possible to identify the presence of a correlation between the performance indicators and the incidence of overheads, in which the likelihood of the presence of “good”, “excellent” or “excellent” indicators is given by levels of overhead in the region of 10% of the total revenue assessed, with a margin of tolerance of 3% in positive for smaller entities (up to 5,000 inhabitants), and 3% in negative for larger entities.

scholarly journals Financial equilibrium as the special capital condition in holding: abilities to achieve

2019 ◽  
Vol 81 (1) ◽  
pp. 351-356
Author(s):  
L. V. Kislitsyna ◽  
S. A. Kapustina
Keyword(s):  
Financial Performance ◽  
Performance Indicators ◽  
Performance Indicator ◽  
Point Of View ◽  
Financial Equilibrium ◽  
Condition Estimation ◽  
Financial Condition ◽  
Strategic Goals ◽  
Current Article ◽  
Special Rules

Modern company development requires not only tactical and strategic goals settings. It also requires to meet specific financial requirements for capital conditions. As it widely known company's capital conditions estimates with financial performance indicators. This method is quite discussion, nevertheless it still widely applicable. From our point of view, «financial equilibrium» as a one of group key financial performance indicator is crucial. In the capital condition estimation while discussing its adequacy to financial equilibrium, special attention should be given to such performance indicators as: liquidity, risk and yield. Balancing those parameters allows to management by default to achieve financial condition that required. Shown issue reveals its especial actuality for holdings, due to its complicated structure of inner communications which made it hard to achieve tactical and strategic goals that been set. Holdings needs to develop and apply special rules for structuring capital flows, which allows to achieve financial equilibrium. This article is about Financial liability limits as a one of factors that impacting holding capital condition. Current article based on researching of the practical approach of financial liabilities limits. Key conclusions revealed in the article.

scholarly journals ECOLOGY OF ARCHITECTURAL (NATURAL-ANTHROPOGENIC) ENVIRONMENT UNDER ABIOTIC ENVIRONMENTAL TRANSFORMATIONS

2021 ◽  
pp. 109-116
Author(s):  
К.S. KHARCHENKO
Keyword(s):  
Environmental Factors ◽  
Performance Indicators ◽  
Environmental Performance ◽  
Point Of View ◽  
Practical Significance ◽  
Anthropogenic Pressure ◽  
Architectural Space ◽  
Material Basis ◽  
Anthropogenic Environment ◽  
Environmental Performance Indicators

Formulation of the problem. Ecology is understood as a science that studies the environment and its relationship with human activity, as well as a means of reducing anthropogenic pressure. Architecture ecology, as a branch of architectural science, needs to expand the methods of studying the regime of environmental factors, as well as trends in their regional change. The purpose of the article is to study the directions of improving methods for determining the characteristics of an architectural space, which can provide a basis for determining environmental performance indicators. When designing local zones of recreational gullies, parks, forests, one should take into account the environment of the transforming and transgressive influence of micro-, meso-, and macrobiogeocenosis systems. Results. Based on the study of experience, it is proposed to systematize the environment from the point of view of ecology. In particular, the following types of architectural and ecological space are distinguished: according to the composition of the material basis − natural, quasi-natural, artificial, combined; by the state of ecological balance − ordered, unstable, violated; after interaction with others − open, half-open, closed, isolated, hermetic; in accordance with the structure − central, peripheral, borderline, linking; from the point of view of energy-informational impact on a person − Biopositive (beneficial), neutral, extreme and pathogenic. Scientific novelty and practical significance. The research carried out by the author has somewhat changed the approach to systematizing the environment from the point of view of ecology. The types of architectural and ecological space are theoretically substantiated. Practical significance dedicated to the concepts of architectural space and issues of its topology, morphology and semiotics, as well as in works on the study of the composition of architectural space, highlight certain aspects of architectural ecology.

Development of System Based Code: Part 2—Application of Reliability Target for Configuration of ISI Request

2010 ◽  
Author(s):  
Shigeru Takaya ◽  
Satoshi Okajima ◽  
Kenich Kurisaka ◽  
Tai Asayama ◽  
Hideo Machida ◽  
...  
Keyword(s):  
Failure Probability ◽  
Reactor Vessel ◽  
Point Of View ◽  
New Method ◽  
Service Period ◽  
Key Points ◽  
Creep Fatigue ◽  
Breeder Reactors ◽  
Analysis Models

The System Based Code (SBC) concept has been proposed to achieve compatibility in matters of reliability, safety, and cost of Fast Breeder Reactors (FBR). This code extends the present structural design standard to include the areas of load setting, fabrication, inspection, maintenance, and so on. Therefore, a quantitative index which can connect different areas is required. In addition, the determination of its target value is also one of the key points to substantiate the SBC concept. Failure probability is one of the candidate indexes. We have proposed a new method to determine the reliability targets for the structures and components in FBR plants from the safety point of view by utilizing analysis models of a probabilistic safety assessment. In this study, the effectiveness of the failure probability as an index and the compatibility of the reliability targets derived by the new method were investigated through a trial setting of In-Service Inspection (ISI) request on the reactor vessel near the sodium surface based on the SBC concept. The failure probability due to creep-fatigue interaction was calculated by the Monte-Carlo simulation. In response, the reliability targets for fracture related to the risk from internal initiating events were derived. Cumulating the failure probability and the reliability targets up to the end of in-service period enables us to compare them directly, and we obtained a result that the reactor vessel has enough reliability even without ISI. Through this trial, we showed that the failure probability is a promising index, and the reliability targets derived by the new method are compatible with the SBC concept.

Verification of the IEC 61508 PFH formula for 2oo3 configuration using Markov chains and Petri nets

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Hanane Omeiri ◽  
Brahim Hamaidi ◽  
Fares Innal ◽  
Yiliu Liu
Keyword(s):  
Markov Chains ◽  
Petri Nets ◽  
Point Of View ◽  
Numerical Comparison ◽  
Content Type ◽  
Iec 61508 ◽  
Safe State ◽  
Reliability Block Diagrams ◽  
Modular Redundancy ◽  
Multi Phase

PurposeThe purpose of this paper is to check the consistency of the IEC 61508 standard formula related to the average failure frequency (PFH: the probability of dangerous failure per hour) for a commonly used safety instrumented system (SIS) architecture in the process industry: 2-out-of-3 voting (2oo3), also known as Triple Modular Redundancy (TMR).Design/methodology/approachIEC 61508 standard provided PFH formulas for different SIS architectures, without explanations, assuming that the SIS puts the equipment under control into a safe state on the detection of dangerous failure. This assumption renders the use of classical reliability approaches such as fault trees and reliability block diagrams impractical for PFH calculation. That said, the consistency verification was performed thanks to a dynamic and flexible reliability approach, namely Markov chains following these steps: (1) developing the multi-phase Markov chains (MPMC) model for 2oo3 configuration, (2) deducing the related classical Markov chains (CMC) model and (3) deriving a new PFH formula for the 2oo3 architecture based on the CMC model and thoroughly comparing it to that given in the IEC 61508. Moreover, 2oo3 architecture has been modeled through Petri nets for numerical comparison purposes. That comparison has been carried out between the numerical results obtained from IEC 61508 formula, the newly derived formula, Markov chains and Petri nets models.FindingsThe newly obtained formula for 2oo3 configuration contains extra terms compared with the IEC 61508 one. Therefore, this latter formula induces an underestimated PFH results, which is dangerous from a safety point of view. This fact was corroborated by the numerical comparison.Research limitations/implicationsThis paper does not consider the different configurations given in IEC 61508.Originality/valueIn our knowledge, no verification works have been conducted before on the IEC 61508 PFH formulas with shutdown capability. Therefore, the nonaccuracy of the PFH formula related to the 2oo3 has not been stated before. This paper proposes a new and more accurate formula.

Sign in / Sign up

Export Citation Format

Share Document