Reliability Indicators Research Articles

Development of measures to optimise the modes of 10 kV electrical networks

The article considers the peculiarities of the structure and functioning of distribution electric power networks of Ukraine. A list of technical and organisational measures has been determined, which, both at the design and operation stages, provide for the possibility of using modern technical means and control technologies to ensure regulatory requirements for the parameters of modes, indicators of the quality of electricity and reliability of electricity supply to consumers, and are the most appropriate for improving the efficiency of distribution electric networks. The paper proposes a criterion for optimising the modes of distribution electric networks, which takes into account the nature of load changes, peculiarities of voltage regulation and reactive power compensation in electric networks, as well as the availability of sources of distributed generation and energy storage systems in the network, and additionally provides for the possibility of analysing the operating conditions of generation devices and power equipment. For the studied 10 kV electrical networks, measures have been developed to ensure the conditions for optimising operating modes with regard to these factors. A description of the proposed algorithm for selecting the most appropriate of the developed measures is given, which takes into account the current situation in the electricity market, general global trends in the development of distribution electric networks, current trends and prospects for the development of technical means of ensuring the parameters of the mode of electric networks, automation systems and intelligent control systems for the modes of the studied electric networks, as well as indicators of power supply reliability and quality of electricity supply services to consumers.

Defining intensity–duration–frequency curves at short durations: a methodological framework

ABSTRACT In the field of sub-hourly durations, and especially in urban hydrology, selecting the most appropriate form of the intensity–duration–frequency (IDF) curve becomes a relevant question. In this study, two different formulations of IDF curves – that are characterized by a curvature in the sub-hourly intervals and a power-law formulation for the super-hourly intervals – are proposed in order to maximize the overall information contribution in the sub-hourly and the super-hourly domains. The proposed formulations are compared with two well-known IDF formulations, respectively characterized by a power-law and a curvature (from the power-law) formulation, calibrated only using data referring to super-hourly durations. Findings indicated that the proposed IDF curves allow to account for the different lengths of the sub-hourly and canonical data series and eventually for the different behaviour/trend of sub-hourly and super-hourly data, thus providing the best reliability indicator, at least in the investigated return period.

Intelligent Assessment Method of Structural Reliability Driven by Carrying Capacity Sustainable Target: Taking Bearing Capacity as Criterion

Large-scale building structures are subject to numerous uncertain loads during their service life, leading to a decrease in structural reliability. Real-time analysis and accurate prediction of structural reliability is a key step to improve the bearing capacity of buildings. This study proposes an intelligent assessment method for structural reliability driven by a sustainability target, which incorporated digital twin technology to establish an intelligent evaluation framework for structural reliability. Under the guidance of the evaluation framework, the establishment method of a structural high-fidelity twin model is formed. The mechanical properties and reliability analysis mechanism are established based on the high-fidelity twin model. The theoretical method was validated by experimental analysis of a rigid cable truss construction. The results showed the simulation accuracy of the high-fidelity twin model formed by the modeling method is up to 95%. With the guidance of the proposed evaluation method, the mechanical response of the structure under different load cases was accurately analyzed, and the coupling relationship between component failure and reliability indicators was obtained. The twinning model can be used to analyze the reliability of the structure in real time and help to set maintenance measures of structural safety. By analyzing the bearing capacity and reliability index of the structure, the safety of the structure under load is guaranteed. The sustainability of structural performance is achieved during the normal service period of the structure. The proposed reliability assessment method provides a new approach to improving the sustainability of building bearing capacity.

Exploring Student Perspectives on Quality Assurance in Independent Curriculum Services within Educational Institutions

This study examines students' perceptions of quality assurance of independent curriculum services implemented by SMA Nurul Jadid. Using a descriptive quantitative approach. With a proportional random sampling technique, as many as 100 students. The type of data collected is quantitative, using a closed questionnaire. The questionnaire was tested for validity and reliability with a significance of 0.05 with the SPSS 16 application. A Likert scale of 1-4 was used to measure student perceptions with positive and negative categories. The following are tangible, reliability, and assurance indicators as indicators of quality assurance for the independent curriculum service. The percent interval is used as a measuring tool to determine the categories of strongly agree/very good, agree/good, disagree/good enough, and strongly disagree/strongly disagree with implementing quality assurance services for the independent curriculum. The research results prove that 58% of students perceive positively and 42% negatively. However, no students rated it as very bad at 0%; in fact, the good category was the most percentage, namely 59%, and even perfect at 7%; there were also those who rated it quite well, as much as 34%. The assessment of the most significant percentage being good is due to the socialization process evenly distributed to all components of the school; staff, teachers, students, and parents. This is done to process the quality assurance of the independent curriculum services provided by schools to run effectively and efficiently.

ANÁLISIS SOBRE LA RESPONSABILIDAD PERSONAL COMO FACTOR PREDICTOR DE LA RESPONSABILIDAD RELACIONAL EN ALUMNADO UNIVERSITARIO ESPAÑOL

Responsibility is an important factor in educating students for freedom or self-determination. Our actions have repercussions not only on ourselves but also on others. Forming in this dimension can also lead to know how to make commitments with others. This article seeks to validate a scale that helps measure the self-perception of personal and relational responsibility in young university students that can help train them in this double dimension and to see, if personal responsibility, is predictor of relational responsibility. The scale was applied to 403 university students (114 men and 289 women) between 18 and 23 years old, selected through a simple random sampling at the Francisco de Vitoria University (Madrid). Internal consistency analysis, parallel analysis and confirmatory factor analysis were performed. The scale is made up of a total of 9 items, grouped into two dimensions (relational responsibility and personal responsibility). The scale presented adequate indicators of internal consistency (α = .678; ω = .740) and goodness of fit (CFI = .953; IFI = .954; RMSEA = .047; χ2 / gl = 1.871). In addition, it was observed that personal responsibility predicts 12.6% of relational responsibility. In a complementary manner, significant differences were observed in relational responsibility in favor of women. This study presents a scale, in Spanish, with reliability and validity indicators to measure the Self-perception of personal and relational responsibility of university students. In addition, evidence was obtained on the predictive capacity of personal responsibility in their relational responsibility

The reality of applying Bologna process in education from the students of Zakho University viewpoint

The current study aimed to identify the viewpoint of the students of University of Zakho about the reality of applying Bologna process in university education, and the significance of the differences in their viewpoints according to the demographic variables: gender, class, and specialization. The sample consisted of (750) male and female students who were chosen in a stratified random manner from the colleges and faculties of University of Zakho. To achieve the objectives of the study, the researchers prepared a questionnaire consisting of (41) items divided into four dimensions. The study’s validity and reliability indicators were verified. The data were treated statistically using the arithmetic means and standard deviations, in addition to using the t-test for one sample and for two independent samples. The results indicated that the reality of applying Bologna Process from the students’ point of view is good or high. Besides, there was a significant difference in the students’ point of view about the reality of applying Bologna Process due to the college variable and in favor of the humanities colleges. No significant differences appeared in their views according to gender and class. In light of the results, a set of recommendations and proposals were presented.

Reliability control of a thermoelectric cooler with changes in ambient temperature

The paper presents the development of method of thermoelectric system reliability indexes control for providing thermal modesof radio electronic equipment, based on thermoelectric coolers medium temperature variation. A mathematical model for investigating influence of the environment temperature variation on the reliability performance of a single-cascade thermoelectric cooler at a given temperature level of cooling, thermal load, geometry of thermoelement branches for different characteristiccurrent operating modes is considered. The results of calculations of the basic parameters, reliability indices, dynamic characteristicsand the analysis of dependences are given for revealing the peculiarities of control processes. It is shown that decreasing the medium temperature at a given chiller design decreases the operating current, increases the cold-productivity, and decreases the time of reaching a steady-state operating mode for various characteristic current operating modes. The time to steady-state operation decreases from the minimum failure rate to the maximum cooling capacity at a fixed medium temperature. The minimum steady-state operation time is ensured in maximum cooling capacity mode. Reduction of such significant for control indices as the amountof consumed energy for different characteristic current operation modes, required heat dissipation capacity of the radiator, time of reaching the steady-state mode is noted. Analysis of research results has shown that it is possible to control indicators of reliability of a single-stage cooler of a given design by changing the medium temperature by changing the value of operating current. A change in the medium temperature of the thermoelectric cooler due to an external supporting device makes it possible to vary the reliability indices and to find a compromise between the reliability, dynamics and cooling capacity of the thermal mode support system.

Development of the structure and methodological support of the system for analysis of the details shaping using the technological inheritability of their quality parameters

Theoretical approaches, computer modell methods and experimental studies analyse the state and behaviour of machine parts to determine the changes in their properties and parameters from a single synergetic position. Development and implementation of integrated information systems for control of technological processes of manufacturing parts and machines assembly is an essential mover of the economic growth of industrialized countries. Complicating the operational conditions for the products increases the requirements for the parameters of their accuracy, surface layer quality, performance characteristics and reliability indicators. A mechanical engineering product is a technical system consisting of many subsystems and using the functionally-oriented design of technological processes planning for parts manufacturing. The structure and methodological providing of the PSPAS-system (Product Shaping / Processing Analysis System) investigates. PSPAS system includes the investigations of the technological inheritability of mechanical engineering product quality parameters combined with the analysis of traditional subsystems (cutting, surface plastic deformation, surface layer modification, assembly). Rheological simulation modelling, holding of experimental studies, the combination of mathematical modelling, theoretical and practical studies of technological processes ensure the implementation of the CAF system using the principle of functionally-oriented design during parts manufacturing and machines assembly.

Psychometric Properties and Factorial Structure of Postpartum-Specific Anxiety Scale (PSAS) Within Arabic Language in a Palestinian Context.

The Postpartum-Specific Anxiety Scale (PSAS) is an international measure designed to evaluate anxiety experienced by mothers in the postpartum period from one day to six months; the scale was translated into Arabic and validated within Palestinian context to test postpartum anxiety among Palestinian women. The current study aimed to test the psychometric properties and the factorial structure within the Arabic language in a Palestinian context using confirmatory factor analysis (CFA). The sample of this study consisted of 475 Palestinian women recruited from health centers in the West Banks of Palestine using a convenience sample. 61% were of ages 20-30 years and 39% percent ages 31-40 years. The PSAS showed good validity and reliability indicators in assessing postpartum anxiety within Palestinian context. Results of CFA showed a stable construct of a four-factor structure in assessing postpartum anxiety among Palestinian mothers: (1) competence and attachment anxieties, (2) infant safety and welfare anxieties, (3) practical baby care anxieties and (4) psychosocial adjustment to motherhood, which is consisting with the original four-factor structure of the scale. The PSAS showed good validity indicators within Palestinian context. Therefore, it is recommended to conduct similar studies with clinical and non-clinical groups in the Palestinian society. The PSAS can be a useful measure to assess anxiety levels among women during the postpartum months; which will enable mental health providers to provide psychological interventions for mothers whose anxiety levels are high.

GAD-7 Generalised Anxiety Disorder scale in Colombian medical professionals during the COVID-19 pandemic: Construct validity and reliability

IntroductionThe detection of anxiety symptoms among health workers who care for patients infected with COVID-19 is a current priority. Fast and valid instruments are required for this population group. The objective is to establish the construct validity and reliability of the Generalised Anxiety Disorder (GAD-7) scale in Colombian doctors during the COVID-19 lockdown. MethodsE-health study, in which cross-sectional data were collected online (n = 1030) from 610 COVID doctors and 420 non-COVID doctors, during the Colombian lockdown, between 20 April and 10 August 2020. Each subject was contacted, and they confirmed their participation, identity and professional role. ResultsA single factor factorial structure was found, made up of the 7 items of the instrument, which managed to explain 70% of the variance. The goodness of fit indices (RMSEA = 0.080; CFI = 0.995; SRMR = 0.053; p < 0.001) showed an “acceptable” unidimensionality and adequate factor loadings in each item of the GAD-7, >0.070. Finally, the internal consistency of the instrument was good, with a Cronbach’s alpha of 0.920 (95%IC, 8.80–9.71). ConclusionsThe GAD-7 is an instrument that presents adequate indicators of validity and reliability. It is an excellent tool that is reliable and easy and fast to use for the detection of generalised anxiety symptoms in medical personnel caring (or not) for patients infected with COVID-19.

Influence of control parameters on the main reliability indicators of machine parts

The mechanisms of influence of tolerances on the formation of indicators of reliability of machine parts are determined. It is established that in order to control the residual life, it is necessary to diagnose the state of a specific machine unit in order to obtain estimated reliability parameters in order to determine the possibility of its further operation. Keywords: reliability, control, failure, life, diagnostics, machine. ykataev@mail.ru

Comparison of the Vortex Chamber Supercharger Characteristics for Grain Pumping with Other Types Superchargers

Problem. Among the superchargers used in pneumatic transport, jet pumps have the best reliability and durability indicators. However, their use in these systems is limited due to the large specific energy consumption indicators for pumping. Vortex chamber superchargers allow to increase the pressure of the medium at the outlet of the pump, in comparison with classic direct-flow jet pumps, but their characteristics during operation in undrained mode have not yet been investigated. Goal. The goal of this work is to analyze the characteristics of vortex chamber superchargers for pumping grain and compare the main integral parameters with the parameters of existing pneumatic devices of other types. Methodology. The study was carried out by comparing the experimental and calculated super-chargers characteristics with the technical characteristics of industrial pneumatic transport units based on direct-flow jet pumps and grain loaders. Results. As a result of the comparison, it was found that the mass flow rate for the solid medium (grain) for the vortex chamber supercharger exceeds the achievable (theoretical) rate of the direct-flow jet pump by 1.1 times and is 15% inferior to the grain loader. Originality. Improving the efficiency indicators of the vortex chamber supercharger allows for expanding the range of pneumatic device usage for grain over-loading. The distance of transportation can be increased to 220 m due to exceeding the indicators of the relative drop in comparison with direct-flow jet devices with an increase in the process efficiency. Compared to suction grain loaders, the vortex chamber supercharger can create a larger pressure drop, but with reduced efficiency. Practical value. The creation of a vacuum in a grain transfer unit is limited to 1 atm, unlike a jet supercharger, which can operate at almost any created pressure drop, which increases the transportation distance.

Construction &amp; Validation of Civic Sense Scale (CSS) in Urdu Language for Pakistani Secondary School Students

Civic sense plays a crucial role in human life. It determines the success and usefulness of a citizen in a society. The civic sense consists of both civic knowledge and civic practices. The students’ civic knowledge or self-perception of civic sense improves their civic practices in the community. This paper describes constructing and validating the Civic Sense Scale (CSS). This scale is prepared to measure students’ civic knowledge and civic practices. Generalized Structural Component Analysis (GSCA) technique is applied in this study. This scale was administered to 1200 Federal Government Educational Institutions students studying in 10th grade in Pakistan. A total of 1196 students out of 1200 students responded to the questionnaire. The data was collected from students through a stratified sampling technique. Both self-perception and civic practices on civic sense consisted of 45 items. There were 23 and 22 items on Civic Sense Scale on self-perception and civic practices, respectively. The reliability indicator Cronbach’s alpha and Rho were observed to be more than 0.7. Likewise, the construct validity, convergent and discriminant validity measures were in acceptable ranges. These show that Civic Sense Scale (CSS) is highly recommended to measure civic sense and its practices in the educational setting. Initially, this study was limited to secondary school students in Federal Government Educational Institutions of Pakistan.

Analysis of the characteristics of reliability indicators of machines and equipment operating in emergency situations and extreme conditions

The article analyzes the main characteristics of the reliability indicators of machines and equipment operated in emergency situations and extreme conditions. Methods for their evaluation are discussed using various methods of probability theory and mathematical statistics. Keywords: machines; equipment; reliability; emergency; extreme conditions; evaluation; probability theory; mathematical statistics.

Efficiency Improvement Methods of Independent Wind Electric Installation with Programmed Control

Relevance justification of effective automated control method of independent wind electric installation on the basis of voltage feedback and parameters of inductance x1, reduced inductance x′2, phase resistance of starter winding r1, reduced phase resistance of starter winding r′2 is made under different conditions of electric installation operation to minimize the time of phase voltage regulation transient process of wind turbine generator, that promotes quality improvement of self-excitation and reliability indicator improvement of energy supply of the basic control under insufficient information of meteorological and electric power conditions significaltly changing in time. The review of basic ways to control independent wind electric installations which has shown their negative sides is made, that revealed their negative sides like low execution speed and reliability, lack required voltage control quality, idle excitation current distortion leading to voltage sine curve distortion of the asynchronous generator, and providing no relay protection or the automatic switch and automation operating mode control. The differential equation of wind turbine rotor angular speed is composed. Transfer functions of dynamic links for generator phase voltage automatic control of wind turbine taking into account wind speed, rotor winding current, inductance, rotor winding phase resistance, reduced stator winding phase resistance are plotted. The block diagram imitating model is constructed and schedules of transient processes with zero and non-zero delay were plotted providing delay negative effect development decision making on stability of wind turbine generator phase voltage and to establish method of relevant system preparation to external disturbances vanishing above mentioned disadvantage.

Improving the mechanism of port handling complexes

The issue of modernization of cargo flow mechanization schemes, while optimizing logistics costs with the aim of increasing port capacity, was considered. The process of cargo transshipment using various lifting and transport machines is studied, the schemes of complex mechanization of port terminals are presented. The main schemes of complex mechanization in the port are analyzed on the example of transportation of artificial cargo - slab. The leading link of these schemes is the gantry crane, for which a dynamic 3D model has been developed, which allows you to create a scenario of the transport operation using simulation systems. With the help of the simulator, it is possible to evaluate indicators of performance and reliability of the crane. The results of the calculations of the characteristics of the warehouse, its capacity and the layout of the slabs are given. To build a logistics algorithm for cargo transportation operations, input data (structure of freight traffic, energy costs, logistics costs), objects (lifting and transport equipment, ships, railway transport) and output information in the form of a report with simulation results are determined. The paper proposes an algorithm for the simulation model of the port transshipment complex, which allows you to visualize the technological process of transshipment operations and optimize the parameters according to the specified quality criteria. The materials of the article can be useful to specialists of the mechanization services of sea and river ports, as well as used in the educational process as tasks for laboratory, practical and course work

Open Access to the JESS Chemical Reaction Database

The JESS (Joint Expert Speciation System) Thermodynamic Database (v8.9) is now available as a set of freely available PDF files. This reaction database contains about 280,000 thermodynamic parameters (equilibrium constants, enthalpies, etc.) as published in the literature for over 80,000 chemical reactions. It is grounded in the tradition of the Stability Constants Special Publications (by the Chemical Society) but it has become much more extensive and it includes some quantitative indication of parameter reliability based mainly on intra- and extra-reaction consistency.

From Conspiracy to Hesitancy: The Longitudinal Impact of COVID-19 Vaccine Conspiracy Theories on Perceived Vaccine Effectiveness.

The embrace of coronavirus disease 2019 (COVID-19) vaccine conspiracies has been linked to vaccine hesitancy. This study aimed to investigate the relationship between COVID-19 vaccine conspiracy theories and perceived vaccine effectiveness. The study utilized a longitudinal follow-up study in which adults in Chile completed surveys in December 2020 (T1) and May 2021 (T2). The psychometric properties of the five-item instrument on conspiracy theories for the COVID-19 vaccine were evaluated using data from T1 (n = 578). A confirmatory one-factor structure with suitable indicators of reliability was found. The longitudinal analysis (n = 292) revealed that conspiracy theories about the COVID-19 vaccine in T1 were associated with lower beliefs in its effectiveness in T2. However, no significant association was found between beliefs in effectiveness in T1 and conspiracy theories in T2. The study suggests that beliefs in conspiracy theories may temporally precede beliefs in vaccine effectiveness for COVID-19. The results have implications for strategies to address vaccine conspiracy beliefs and their implementation at the public policy level.

Introducing the Validation of Data Quality Indicators Through Re-Classification: The example of SQP and pretest surveys

The present study introduces the concept of validating data quality indicators through re-classification. We use the term re-classification to mean the evaluation of how well an indicator detects the quality of different versions of a survey question for which the quality is known a priori. We illustrate its application with two examples. In both, we make use of 12 questions from prior experiments that manipulated text features of questions to create ‘low’ and ‘high’ quality versions of each question. In the first example, we coded each question version in SQP 2.1 to obtain indicators of validity, reliability, and quality. We compared these indicators between the two versions of each question to assess whether the SQP outcomes were sensitive to text features. In the second example, we used a pretest survey to obtain three indicators of survey quality: response latencies, item nonresponse, and consistency over time. Again, we compared these indicators between question versions to assess whether the indicators were sensitive to text features. We give recommendations for applying re-classification and an outlook for future research opportunities.

Algorithm for implementation of the method of justification of the minimum necessary number of parameters of technical means of intelligence for monitoring their technical condition

In the article the solution to one of the problems of technical diagnostics is offered for the first time — minimizing the number of parameters for constant monitoring of their values during the operation of technical means of intelligence. They include systems of special radio communication, signal intelligence and many others. Their functioning is objectively evaluated by a set of parameters, the values of which are impractical to constantly monitor due to significant cost and redundancy as well as the presence of interdependent parameters in the system. Therefore, there is a task of determining their minimum acceptable number according to a well-founded criterion that objectively assesses the readiness of the system to perform the necessary functions. The solution to the problem depends on the importance of the parameters for the system user, the volume of the inspected part of the complex, the cost of built-in controls and other quality indicators, which are combined by a complex indicator. Its value is normalized by the probability of the preferred choice of the parameter for monitoring the technical condition of the product. The ranking of parameters according to this indicator allows you to justify their minimum necessary number for monitoring while ensuring the predetermined value of the control quality indicator. The article proposes a scheme, a mathematical apparatus and an algorithm for the implementation of the method of substantiating the minimum necessary number of parameters for condition monitoring. The obtained results with the use of information technologies make it possible to predict the technical condition of the control object in order to maintain the required values of reliability indicators.