Tag Archives: reliability

xxx V. Hartová, J. Hart and M. Kotek
Reliability of palms security under difficult conditions
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Reliability of palms security under difficult conditions

V. Hartová¹*, J. Hart² and M. Kotek¹

¹Czech University of Life Sciences Prague, Faculty of Engineering, Department of Vehicles and Ground Transport, Kamýcká 129, CZ16500 Prague, Czech Republic
²Czech University of Life Sciences Prague, Faculty of Engineering, Department of Technological Equipment of Buildings, Kamýcká 129, CZ16500 Prague, Czech Republic
*Correspondence: nidlova@tf.czu.cz

Abstract:

Reliability of biometric identification systems is a much discussed topic and nowadays security of premises is very important. The work is focused on palms security research and reliability of the system under adverse conditions, the aim of the measurement was to determine the reliability of readers under adverse conditions that may occur in an industrial environment. Difficult conditions include dirty surface of hand by water, dust, oil and writing accessories. First, a sample measurement was carried out, where the hands of the subjects were washed and thoroughly dried. This measurement was used to compare with measurements under adverse conditions. The results show that the more viscous the fluid the lower the reliability and also dusty hands caused considerably distorted results. The reliability of biometric systems still needs to be improved, as it often happens that the real values do not match the parameters that are declared by the manufacturers. Certain conditions must be met for the proper functioning of palms security, so that identifying persons are allowed access to the protected areas and have not been repeatedly denied.

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993–1000 V. Hartová, M. Kotek, J. Hart and Š. Pícha
Reliability of parking assistants depending on the material of detected obstacles
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Reliability of parking assistants depending on the material of detected obstacles

V. Hartová¹, M. Kotek¹, J. Hart² and Š. Pícha¹

¹Czech University of Life Sciences Prague, Faculty of Engineering, Department of
Vehicles and Ground Transport, Kamýcká 129, CZ165 00 Prague, Czech Republic
²Czech University of Life Sciences Prague, Faculty of Engineering, Department of
Technological Equipment of Buildings, Kamýcká 129, CZ165 00 Prague, Czech Republic
*Correspondence: nidlova@tf.czu.cz

Abstract:

Today’s modern vehicles are equipped with a range of assistance systems to enhance road safety. The standard equipment of most cars are parking assistants. It turns out that not always sensors can reliably detect the obstacle on the travel path of the vehicle. The aim of the paper is to determine the reliability of the parking sensors depending on the material of the obstacle detected. The original parking assistants of Škoda Rapid, Škoda Octavia II, and Škoda Superb have been tested in laboratory conditions using obstacles made of various materials (glass, mirror, plastic, metal, cardboard …) located at distance of 100 cm from the vehicle. Distance values of the original sets of parking assistants were measured during the measurement from onboard diagnostic vehicle using diagnostic kit VAG-COM. The real distance was checked using a calibrated gauge. The results of the research show, that original sets of parking assistants achieve significantly more accurate results with a wider coverage of the space being scanned. Material composition of obstacles has a great influence on the reliability of parking systems. Not every material can respond properly to parking sensors.

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680–686 M. Forsman
The search for practical and reliable observational or technical risk assessment methods to be used in prevention of musculoskeletal disorders
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The search for practical and reliable observational or technical risk assessment methods to be used in prevention of musculoskeletal disorders

M. Forsman

Institute of Environmental Medicine, Karolinska Institutet, SE-171 77 Stockholm, Sweden
Correspondence: mikael.forsman@ki.se

Abstract:

Work-related musculoskeletal disorders (WRMSDs) are still frequent, inducing very large costs for companies and societies all over the world. Ergonomists work to prevent these disorders and to make organisations sustainable. In their work it is important to identify risks in a reliable way, to prioritise risks, and then to perform interventions (participatory interventions have shown to more often be successful), so that the risks and the disorders may be reduced. Risks are most often assessed by observation. Two projects are described. In the first project the interobserver reliability of six observational methods was found to be low in risk assessments concerning repetition, movements and postures. Also the inter-method reliability was often low, i.e. when the same work is assessed with different methods different risk estimates are often obtained. In the second described project, easy-to-use methods for measurements of postures and movements were developed and validated. Hence, there are now validated technical methods that are easy to use. But, today’s inexpensive electronic devices should be utilized to a higher degree, in developing tools, together with practitioners, that are attractive, easy and time efficient to use, and which should increase the reliability in risk assessments of work tasks and jobs.

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817–829 M. Prístavka, K. Krištof, and P. Findura
Reliability monitoring of grain harvester
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Reliability monitoring of grain harvester

M. Prístavka¹, K. Krištof²,* and P. Findura²

¹ Slovak University of Agriculture in Nitra, Faculty of Engineering, Department of Quality and Engineering Technologies, Tr. A. Hlinku 2, SK949 76 Nitra, Slovak Republic
² Slovak University of Agriculture in Nitra, Faculty of Engineering, Department of Machines and Production Biosystems, Tr. A. Hlinku 2, SK949 76 Nitra, Slovak Republic
*Correspondence: koloman.kristof@uniag.sk

Abstract:

This paper is focused on evaluation of operating reliability of grain harvesters. The aim of research is to improve the efficiency of combine harvesters by calculations which indicate a minimum annual performance and try to move in profit despite the high annual costs. Methods of paper containing all conditions of monitoring and evaluating of responsibility of grain harvesters. Those harvesters worked in real operating conditions. During three years of monitoring all important and other facilities and conditions of watching were recorded. After accumulation of information, their following working was set out according to the given literary sources and according to the own discretion based on experience during monitoring. The last part is focused on evaluating results and personal proposals how to make individual components work more effective. The most important results was recorded in case of turning point calculation where in years 2013, 2014 and 2015 at values 157.93, 156.19 and 166.86 ha year-1, respectively. However, real annual performance was recorded at values 760.5, 604.6 and 905.5 ha year-1. Thus, in all years of observation the grain harvester finished in profits.

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1161–1168 A. Gedzurs
Operation reliability of induction motors at egg processing plant ‘Balticovo’
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Operation reliability of induction motors at egg processing plant ‘Balticovo’

A. Gedzurs

Latvia University of Agriculture, Faculty of Engineering, Institute of Energetics, J. Cakstes blvd. 5, LV-3001 Jelgava, Latvia; e-mail: aleksejs.gedzurs@llu.lv

Abstract:

In hen houses air quality plays an important role in egg production volume. However, failure of fan induction motors often occurs and it is important to improve reliability of these. A motor reliability study was conducted in the egg processing plant ‘Balticovo’ in Iecava. Results show that 86% of failed number from 2010–2015 occur in hen houses and more than 50% of them were failures of motors which drive the fan. Annual failure rate of fan induction motors each year was increasing and in 2015 it was 6%. Investigations of the faulty motors showed the following defects – stator turn to turn failure of stator winding insulation leadwire and stator winding insulation thermal stress and mechanical damage of stator core resulting in the damaged stator winding leading to a short circuit. Results show that conditions that could contribute to such defects are excessive heating and vibrations.

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