Detecting and analysing condition of hydraulic oils with on-line sensorsVito Tič
, Darko Lovrec
, 2011, izvirni znanstveni članek
Opis: On-line condition monitoring of the entire system or individual components can be used for detection of impending system break-down. The on-line monitoring of the state of hydraulic system and fluid plays a decisive role in general on-line condition monitoring. Friction, wear, leakage and excessive temperatures all have impact on lubricating properties of the oil. Apart from this, the oil its self is prone to aging and deterioration processes, which can also result in corrosion and equipment failures. The oil condition can be understood as a fingerprint of the condition of the complete system. Due to a widespread availability of robust and cost-effective on-line sensors for measuring various fluid properties, latest developments deal with on-line oil condition monitoring to determine the condition of hydraulic system and fluid. This allows for maintenance work to be carried out based on the detected system condition.
Ključne besede: oil ageing, condition monitoring, physical properties, chemical properties
Objavljeno: 01.06.2012; Ogledov: 628; Prenosov: 10
Polno besedilo (0,00 KB)
Gold in the past, today and futureRebeka Rudolf
, Maša Anžel
, Evgenija Marković
, Miodrag Čolić
, Dragoslav Stamenković
, 2012, pregledni znanstveni članek
Opis: This paper deals with gold, which is described as a chemical element. Special attention is paid to its physical-chemical properties and, furthermore, where or in what form it can be found in nature. We discuss the role it has played through history and we inform how gold has been developed to the level it has reached today's value. Still more, when gold is broken into nanoparticles, this form could be highly useful for a wide range of processes, including general nanotechnology, electronics manufacturing and the synthesizing of different functional materials. It is important that we know that gold is also used in industry in many engineering applications (contacts in micro-electronics) and medicine (dental alloys, implants).
Ključne besede: gold, physical-chemical properties, nano-particles, applications
Objavljeno: 01.06.2012; Ogledov: 669; Prenosov: 11
Polno besedilo (144,60 KB)
Compact spinning for improved quality of ring-spun yarnsMomir Nikolić
, Zoran Stjepanović
, Franc Lesjak
, Andrej Štritof
, 2003, izvirni znanstveni članek
Opis: A new impulse in the field of ring spinning technology is offered by compact-condensed spinning. The article presents the comparison of two chosen spinning systems for the production of compact yarns. We have analysed and compared the physical, mechanical and morphological properties of conventional and compact yarns, spun at the same technological and kinematical parameters from the same cotton, cotton/PES and cotton/viscose roving. The construction specificities of the Suessen and Zinser compact ring spinning frames, on which the comparative spinning was performed, are described within this work. The purpose of the study was to determine the influence of differences in compacting systems on yarn quality, and to compare the compact and conventional yarns produced.
Ključne besede: textile industry, ring spinning, compact spinning, compact yarns, mechanical properties, physical properties
Objavljeno: 01.06.2012; Ogledov: 792; Prenosov: 4
Polno besedilo (0,00 KB)
Chiral discrimination in mobile phases for HPLCRenato Lukač
, Andrew J. Clark
, Syma Khalid
, Alison Rodger
, Alan Snedden
, P. Mark Rodger
, 2002, izvirni znanstveni članek
Opis: In this paper we present an algorithm and some preliminary results of a computer simulation study designed to elucidate the molecular interaction mechanisms associated with chiral discrimination in chiral high performance liquid chromatography (HPLC). Molecular dynamics simulations have been performed on a novel active stationary phase constituent based on disaccharides and a model analyte in a typical solvent used as mobile phase in chiral HPLC. The results are interpreted in terms of typical binding geometries and energies found from the simulations. This paper provides basic algorithms for predicting enantiometric selectivity and for investigating the implications for choice of parameters such as solvent polarity and temperature for optimising chiral HPLC separations
Ključne besede: physical chemistry, liquid crystals, liquid chromatography, computer simulations, spectroscopy
Objavljeno: 07.06.2012; Ogledov: 498; Prenosov: 1
Polno besedilo (0,00 KB)
Excess molar volumes of binary liquid mixtures of cyclohexane-carbon tetrachloride and toluene-benzene at various temperaturesAljana Petek
, Valter Doleček
, 1998, izvirni znanstveni članek
Opis: Excess molar volumes of binary mixtures of cyclohexane-carbon tetrachloride at 288.15, 293.15, 298.15 K and toluene-benzene at 293.15, 298.15, 308.15 K have been determined using a vibrating tube densimeter. Flory's theory of liquid mixtures has been applied to calculate the excess entalphy of cyclohexane-carbon tetrachloride at 298,15 K. The calculated value for the equimolar mixture is in fairly good agreement with experimental results.
Ključne besede: physical chemistry, molar volumes, measurements, excess enthalpy
Objavljeno: 10.07.2015; Ogledov: 379; Prenosov: 1
Polno besedilo (117,29 KB)
Disability in patients with chronic non-specific low back painZalika Klemenc-Ketiš
, 2011, izvirni znanstveni članek
Opis: Aim: To validate the Slovene version of the Oswestry Disability Index.
Method: A case series study of 129 adult patients with non-specific chronic low back pain attending a 10-day physical therapy programme. Visual Analog Pain Scale (VAS), Euroqol questionnaire (EQq), and Oswestry Disability Index (ODI) were used at the beginning and at the end of the physical therapy programme.
Results: Cronbach's a of the Slovene ODI was 0.876 at the beginning of the physical therapy programme and 0.901 at the end of the programme. All items of the questionnaire loaded on the same factor. A significant positive correlation existed between the Slovene ODI and VAS, EQ-5D and EQ-VAS at the beginning of the physical therapy programme (r=0.630, p<0.001; r=0.657, p<0.001; r=-0.510, p<0.001, respectively), as well as at the end of the programme (r=0.491, p<0.001; r=0.725, p<0.001; r=-0.648, p<0.001, respectively). The difference between ODI scores obtained at the first and at the second interview was 2.7 ± 5.2 (p<0.001), and the difference between ODI disability scores was 5.4 ± 10.5 (p<0.001). The effect size of the Slovene ODI questionnaire was 0.30.
Conclusions: The Slovene ODI questionnaire is a reliable and valid instrument for assessing outcomes of physical therapy in patients with chronic non-specific low back pain.
Ključne besede: disability evaluation, low back pain, physical therapy, validation studies, questionnaire
Objavljeno: 05.04.2017; Ogledov: 164; Prenosov: 6
Polno besedilo (152,66 KB)
Burnout of older and younger employees - the case of SloveniaMaja Rožman
, Sonja Treven
, Vesna Čančer
, Marijan Cingula
, 2017, izvirni znanstveni članek
Opis: Background and Purpose: People spend a significant part of their lifespan working, but the role of age in job design and implementation of work have largely been ignored. The consequences can be evident in stress and burnout in different symptoms. Thus, age-diverse employees are faced with different symptoms of burnout and stress when carrying out their work. The main aim of this paper is to present burnout of older employees compared to younger employees in Slovenian companies.
Design/Methodology/Approach: The paper is based on research including a survey between two age groups of employees, namely the younger employees that were classified in the group of under 50 years of age and the older employees that were classified in the group of above 50 years of age. Since the Kolmogorov-Smirnov and Shapiro- Wilk test showed that the data was not normally distributed, the noan-parametric Mann-Whitney U test was used to verify differences in the physical symptoms of burnout, emotional symptoms of burnout, and behavioral symptoms of burnout in the workplace between two groups.
Results: The results show that there are significant differences in the great majority of the variables describing the physical symptoms of burnout, emotional symptoms of burnout, and behavioral symptoms of burnout in the workplace between younger and older employees.
Conclusion: Well-being in the workplace of age-diverse employees is a key for long-term effectiveness of organizations. Managers and employers should apply appropriate measures to reduce burnout as well as to contribute to employees well-being and better workplace performance.
Ključne besede: physical symptoms of burnout, emotional symptoms of burnout, behavioral symptoms of burnout, employees, human resource management
Objavljeno: 06.04.2017; Ogledov: 215; Prenosov: 6
Polno besedilo (403,94 KB)
Contingency factors influencing implementation of physical asset management practicesDamjan Maletič
, Matjaž Maletič
, Basim Al-Najjar
, Katerina Gotzamani
, Maria Gianni
, Boštjan Gomišček
, 2017, izvirni znanstveni članek
Opis: Purpose: The purpose of this empirical study is to examine the role of two contingency factors, i.e. uncertainty and competitiveness in relation to physical asset management (PAM) practices as well as to maintenance key performance indicators. The research is based on a premise that PAM, which was defined by risk management practices, performance assessment practices, life cycle management practices, and policy & strategy practices, has become an indispensable element of strategic thinking of asset owners as well as maintenance and asset managers. The purpose of this study is to advance the understanding of how organizations that face high or low level of uncertainty and competitiveness respond in terms of PAM deployment.
Methodology/Approach: This study employed a data set based on a large-scale survey among organizations in six European countries (i.e. Slovenia, Poland, Greece, Sweden, Turkey and Slovakia). Data were collected from 138 organizations located in the above-mentioned countries to conduct the study.
Findings: The results show that organizations that are faced with high level of uncertainty and competitiveness are more engaged in the deployment of PAM practices. Moreover, results show that when organizations are facing high levels of competitiveness they are using KPIs to a greater extent than organizations under low levels of competitiveness.
Originality/value: From a theoretical perspective, this study contributes to the contingency theory by providing empirical evidence whether a context-dependent approach to PAM is needed. The findings also provide insights for managers on how to respond to the competitive pressure as well as how to customize PAM practices in order to adapt to the changes in dynamic organizational environment.
Ključne besede: physical asset management, maintenance, uncertainty, competitiveness
Objavljeno: 06.04.2017; Ogledov: 203; Prenosov: 1
Polno besedilo (675,00 KB)
Exergy analysis of a Brayton cycle with variable physical properties and variable composition of working substanceMarija Živić
, Antun Galović
, Jurij Avsec
, Mario Holik
, 2016, izvirni znanstveni članek
Opis: The exergy analysis of a Brayton cycle is performed in the paper. The four input variables: the ratio of the compressor exit and inlet pressures, the ratio of inlet temperature of gases in turbine and inlet temperature of air in compressor and the isentropic efficiencies of the compressor and turbine are analysed. The temperature ratio is varied in a way that the compressor inlet temperature of air is maintained constant, while the turbine inlet temperature of flue gases is varied from 900 to 1200°C. In the combustion chamber methane is completely combusted with excess air ratio which is determined by the temperature of flue gases at the turbine inlet. The analysis further includes variability of the molar heat capacities of air and flue gases with temperature and variability of their heat capacity ratios. The exergy destruction in turbine, compressor and combustion chamber and also total exergy efficiency of the cycle are considered in the analysis.
Ključne besede: Brayton cycle, variable physical properties, variable composition of working substance, maximum work output, maximum thermal efficiency
Objavljeno: 12.07.2017; Ogledov: 167; Prenosov: 4
Polno besedilo (789,62 KB)