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New approach to uncertainty evaluation in the calibration of gauge block comparators
Andrej Godina, Bojan Ačko, Marjan Družovec, 2007, izvirni znanstveni članek

Opis: Gauge blocks (GBs) are being calibrated by two methods: interferometric calibration and calibration by mechanical comparison to reference GB. While interferometric method represents primary level, comparison is more suitable for calibrating industrial GBs because of lower costs and shorter calibration time. Although no significant changes in equipment happened in last decade, improvements in mechanical comparison are on-going. In addition to the uncertainty of the reference GB calibration, uncertainty of the GB comparator is the most important contribution to total uncertainty of the mechanical calibration. The article introduces a new approach for evaluating the uncertainty of GB comparator calibration. The uncertainty budget and results of analytical and experimental evaluation of all contributions are presented. This approach results in lower end-effect uncertainty and a slightly higher length dependent uncertainty, in comparison with the uncertainty evaluation procedure as described in EA document EA-10/02.
Ključne besede: measurements, calibration, measuring uncertainty, gauge block, comparator, CMC, mechanical comparison
Objavljeno: 31.05.2012; Ogledov: 1393; Prenosov: 62
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4.
Measurement uncertainty in calibration of measurement surface plates flatness
Andrej Gusel, Bojan Ačko, Vedran Mudronja, 2009, izvirni znanstveni članek

Opis: Ravno merilno površino, kot je to na primer merilna plošča, lahko smatramo kot izhodišče za izvajanje večine meritev oblike in lege merjenih objektov. Da bi merilne plošče v ta namen zadovoljivo uporabljali, moramo najprej zagotoviti, da so res ravne in primerne za meritve. Ravnost merilne ploskve ugotavljamo posredno, tako da najprej določimo premost posameznih linij, ki so sestavni del merilne mreže. Te linije so še dodatno razdeljene na merilne korake, ki so prirejeni meram merilne opreme. Premost merilne linije izračunamo z merjenjem nagiba posameznega merilnega položaja za vsako linijo posebej, neravnost celotne površine pa tako, da rezultate po linijah povežemo v celoto. Osnove, postopki in merilne naprave za izvajanje meritev so torej znani, neznanka pa ostaja negotovost tovrstne kalibracije merilne površine. Meritev brez ustrezno izražene negotovosti ne pomeni ničesar, zato moramo zagotoviti, da bomo lahko negotovost določili. Pričujoči članek predstavlja nov pristop določanja merilne negotovosti pri merjenju ravnosti, ki temelji na uporabi metode Monte Carlo. Pri tem celoten merilni sistem razstavimo na posamezne komponente ter ocenimo njihovo veličino in vplive le teh, meritve pa simuliramo. Zanima nas tudi vpliv parametrov merilne mreže na meritev.
Ključne besede: production measurements, length measurements, measuring uncertainty, calibration, uncertainty measurement, flatness measurement
Objavljeno: 31.05.2012; Ogledov: 1092; Prenosov: 22
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5.
Calibration of electronic levels using a special sine bar
Bojan Ačko, 2005, izvirni znanstveni članek

Opis: Electronic levels are designated for the precise measurement of inclination angles within the range of +- 3 mm/m. They are very often used for checking the straightness of machine tool guides as well as the flatness of different kindsof machine tool tables and surface plates. Typical resolution of such instruments is 1 m/m. Electronic levels are calibrated by using very precise angle generators. One such generator is a sine bar. Sine bars are cheap and enable fast and simple calibrations. Commercial sine bars however are not precise enough. We, therefore, decided to design a special sine bar, which would be able to generate angles within an uncertainty of 1 mžm. This sine barwas designed by the laboratory staff and manufactured in our workroom. We have also created a calibration procedure, which has already been accredited. Uncertainty analysis, including experimental measurements, shows that the planned uncertainty has been reached. The sine bar design, calibration procedure and uncertainty evaluation are presented in this article.
Ključne besede: production measurements, measuring uncertainty, calibration, inclination angles, flatness measurements, sine bar, electronic level
Objavljeno: 01.06.2012; Ogledov: 1533; Prenosov: 55
URL Povezava na celotno besedilo

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Uncertainty of nitrate and sulphate measured by ion chromatography in wastewater samples
Brigita Tepuš, Marjana Simonič, 2007, izvirni znanstveni članek

Opis: This paper presents an evaluation of measurement uncertainty regarding the results of anion (nitrate and sulphate) concentrations in wastewater. Anions were determined by ion chromatography (EN ISO 10304-2, 1996). The major sources of uncertainty regarding the measurement results were identified as contributions to linear least-square or weighted regression lines, precision, trueness, storage conditions, and sampling. Determination of anions in wastewater is very important for the purification procedure, especially the amount of nitrate in waste and potable waters. The determined expanded uncertainty was 6% for nitrate anions and 8.3% for sulphate anions. The difference between measurement uncertainties determined by the two methods, the weighted and linear least-square methods is negligible.
Ključne besede: wastewater, nitrates, sulphates, measurements, measuring uncertainty
Objavljeno: 01.06.2012; Ogledov: 1057; Prenosov: 134
.pdf Celotno besedilo (254,17 KB)
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7.
Velocity measurements in a shotblasting machine
Aleš Hribernik, Gorazd Bombek, Ivan Markočič, 2003, izvirni znanstveni članek

Opis: Abrasive shotblasting particles and a high concentration of dust within the closed testing chamber make particle velocity measurement in a shotblasting machine very difficult. The application of non-obstructive optical methods is usually impossible. Robust shields protecting the sensors from abrasion have to be used for contacting velocity measurements and make direct application of capacitive or electrodynamic sensors usually applied in the correlation-based velocity measurements methods not possible. An alternative electronic measurement system has been developed. It has a simple construction and uses low cost elements which can be replaced very quickly and, therefore, no robust shields are necessary. This enables very good mobility and positioning of the sensor along both axis in a cross-section plane of a particle stream. The system has been tested along with a robust mechanical measuring device. The development, operation and application of mechanical and electronic particle velocity measurement system are described in this paper. Experimental results are presented, discussed and both methods are compared.
Ključne besede: shotblasting machines, velocity measurements, particle velocity, mechanical measuring devices, electronic measuring systems
Objavljeno: 01.06.2012; Ogledov: 936; Prenosov: 37
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8.
The psychometric properties of the Slovenian translation of the Francis Scale of Attitude toward Christianity : a study among Roman Catholic undergraduate students
Sergej Flere, Rudi Klanjšek, Leslie John Francis, Mandy Robbins, 2008, izvirni znanstveni članek

Opis: In order to contribute to a growing international research programme concerned with the correlations, antecedents and consequences of individual differences in attitude toward religion, the Francis Scale of Attitude toward Christianity was translated into Slovenian. Data provided by a sample of 808 undergraduate students affiliated with the Roman Catholic Church supported the internal consistency reliability and construct validity of this instrument and commended it for further use in studies conducted in Slovenia.
Ključne besede: psychology, religion, measuring, attitudes, Slovenia, students
Objavljeno: 07.06.2012; Ogledov: 804; Prenosov: 48
URL Povezava na celotno besedilo

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Measuring information security performance with 10 by 10 model for holistic state evaluation
Igor Bernik, Kaja Prislan, 2016, izvirni znanstveni članek

Opis: Organizations should measure their information security performance if they wish to take the right decisions and develop it in line with their security needs. Since the measurement of information security is generally underdeveloped in practice and many organizations find the existing recommendations too complex, the paper presents a solution in the form of a 10 by 10 information security performance measurement model. The model—ISP 10×10M is composed of ten critical success factors, 100 key performance indicators and 6 performance levels. Its content was devised on the basis of findings presented in the current research studies and standards, while its structure results from an empirical research conducted among information security professionals from Slovenia. Results of the study show that a high level of information security performance is mostly dependent on measures aimed at managing information risks, employees and information sources, while formal and environmental factors have a lesser impact. Experts believe that information security should evolve systematically, where it’s recommended that beginning steps include technical, logical and physical security controls, while advanced activities should relate predominantly strategic management activities. By applying the proposed model, organizations are able to determine the actual level of information security performance based on the weighted indexing technique. In this manner they identify the measures they ought to develop in order to improve the current situation. The ISP 10×10M is a useful tool for conducting internal system evaluations and decision-making. It may also be applied to a larger sample of organizations in order to determine the general state-of-play for research purposes.
Ključne besede: information security, organizations, efficiency, measuring, security management
Objavljeno: 19.06.2017; Ogledov: 303; Prenosov: 170
.pdf Celotno besedilo (2,92 MB)
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10.
Implementation of EasyTime formal semantics using a LISA compiler generator
Iztok Fister, Marjan Mernik, Iztok Fister, Dejan Hrnčič, 2012, izvirni znanstveni članek

Opis: A manual measuring time tool in mass sporting competitions would not be imaginable nowadays, because many modern disciplines, such as IRONMAN, last a long-time and, therefore, demand additional reliability. Moreover, automatic timing-devices based on RFID technology, have become cheaper. However, these devices cannot operate as standalone because they need a computer measuring system that is capable of processing incoming events, encoding the results, assigning them to the correct competitor, sorting the results according to theachieved times, and then providing a printout of the results. This article presents the domain-specific language EasyTime, which enables the controlling of an agent by writing the events within a database. It focuses, in particular, on the implementation of EasyTime with a LISA tool that enables the automatic construction of compilers from language specifications, using Attribute Grammars.
Ključne besede: domain specific modelling language, compiler, code generator, measuring time
Objavljeno: 06.07.2017; Ogledov: 407; Prenosov: 164
.pdf Celotno besedilo (409,44 KB)
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