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1.
Questionable research practices
Gorazd Meško, Aleksander Koporec, 2010, pregledni znanstveni članek

Opis: Purpose: The purpose of this article is to discuss deviance in science due to increasing pressures on researchers and higher education pedagogues to be more effective and efficient in the ‘academic production’. Design/Methods/Approach: A literature review and reflection. Findings: The authors present a criminological view of deviance in science, discussing the perception of unsuitable scientific and research practices, questionable research practices, ethics and integrity in science, suitable behaviour of researchers in scientific work, and make recommendations for improving the ethics of scientific research in practice. The discussion on deviance in science is based on Merton’s principles of science (1973): the public presentation of knowledge and sharing of ideas, leading to common ownership of scientific discoveries, in which scientists disclaim their intellectual rights to their own insights in exchange for recognition and reputation. An impartial approach and universalism, in which truth is judged by impersonal, universal criteria, rather than based on race, social and economic status, sex, faith, or nationality and other subjective categories is presented and questioned. A non-profit/selfless orientation in which scientists are rewarded for selfless activities, and planned/organized scepticism – that all ideas must be tested, subject to rigorous scientific rules and public disclosure. The authors discuss these principles and connect them with scientific and research practice in Slovenia and abroad. Research limitations/implications: Research results are generalisable as deviance in science occurs in all cultures and have a global impact. Deviance in science is still an under-researched taboo topic and it needs to be discussed. Practical implications: A useful source of information for awareness raising and the improvement of quality of research work. Originality/Value: This paper extends understanding of possible deviance in science and factors related to such practices. The main value of this reflection is to facilitate understanding of factors of deviance in science and trigger a discussion on deviance among scientists.
Ključne besede: science, deviance, research, academic promotion standards, strain
Objavljeno: 12.05.2020; Ogledov: 300; Prenosov: 11
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2.
Work-Home conflict and strain: the role of work-related smartphone use, job insecurity and segmentation preferences
Tjaša Srnko, 2018, magistrsko delo

Opis: Nowadays, through organisational and technological changes, organizations expect availability and work from their employees not just during working hours, but also in their free time. Work can be done from anywhere and at any time, also with the help of smartphones, which is one of the main constructs of the current research. If the employee is working from home on their smartphone, this can have an important contribution to managing work and private life, and also to strain. The individual’s preference of whether to segment his or her work from home also plays an important role in experiencing internal conflicts. As the motivation for work-related smartphone use is not fully clear, job insecurity was additionally explored as a potential predictor. In an online study, conducted in Austria, we collected data from 454 participants of different ages, gender and working backgrounds. For the analysis, multiple moderated regression and mediation analyses were used. Results showed significant relations between work-home interference and strain but no significant results between those constructs while adding work-related smartphone use. Segmentation preferences did not have an influence on the relationship between work-home interference and strain. Job insecurity was revealed to be related to work-related smartphone use and smartphone use to work-home interference. Smartphone use was also found to partially mediate the path from job insecurity to work-home interference. Finally, to prevent negative outcomes of strain, work-home interference and job insecurity, organizations should focus on: providing culture that fits their employees, try to plan availability free time and provide a clear communication.
Ključne besede: Smartphone use, work-home interference, strain, stress, job insecurity, segmentation preferences
Objavljeno: 14.01.2019; Ogledov: 704; Prenosov: 81
.pdf Celotno besedilo (863,72 KB)

3.
Modified coefficient of subgrade reaction to laterally loaded piles
Ayhan Gurbuz, 2018, izvirni znanstveni članek

Opis: An accurate prediction of the load capacity of a laterally loaded pile at a permissible displacement is an important concern at the design stage. In contrast to many sophisticated methods, Broms’ method based on moment equilibrium has been preferred by engineers to predict the load capacities of laterally loaded piles due to both its simplicity and because it is established on a way of hand calculation. However, Broms’ method typically overestimates a pile’s lateral load capacity as it requires a constant coefficient of horizontal subgrade reaction (nh) into analyses, regardless of the magnitude of the pile’s top displacement. In this study, modified coefficients of subgrade reactions(nh*) that are sensitive to the pile’s top displacement in cohesionless soils are first proposed to improve the performance level of Broms’ method for the prediction of the load capacity of a laterally loaded pile as the pile’s top displacement increases. The modified values of nh* are calibrated using 45 independently free-head, single-driven, full-scale pile tests from 23 sites in cohesionless soils. It is demonstrated that Broms’ method with nh* would correctly estimate a pile’s lateral load-deflection behavior with accuracy levels similar to more complicated methods.
Ključne besede: Broms' method, coefficient of horizontal subgrade reaction, p-y curves, strain wedge model
Objavljeno: 11.10.2018; Ogledov: 590; Prenosov: 309
.pdf Celotno besedilo (735,27 KB)
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4.
A comparison of linear and nonlinear seismic tunnel-ground interaction analyses
Elefterija Zlatanović, Marina Trajković-Milenković, Dragan Lukić, Stanko Brčić, Vlatko Šešov, 2016, izvirni znanstveni članek

Opis: In order to study the effects of a seismically induced tunnel–ground interaction, two-dimensional numerical analyses are performed using the sofware ANSYS. The study employs a coupled beam–spring model subjected to earthquake loading that is simulated under pure shear conditions and determined by a free-field ground-response analysis using the code EERA. The properties of the soil material are considered as both linear and nonlinear. The results obtained by linear dynamic analyses are compared with state-of-practice analytical elastic solutions. A comparison of the results of both linear and nonlinear analyses is also performed, and significant differences, as well as important factors influencing the tunnel–ground interaction for both cases, are evaluated.
Ključne besede: circular tunnel, linear/nonlinear soil behaviour, beam–spring model, plane-strain conditions, simplified dynamic FE analysis, soil–structure interaction
Objavljeno: 18.06.2018; Ogledov: 452; Prenosov: 36
.pdf Celotno besedilo (1,57 MB)
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5.
Influence of the virtual strain rate of noncohesive granular media on the discrete element method
Kiichi Suzuki, 2015, izvirni znanstveni članek

Opis: The discrete element method (DEM) is an alternative computational tool for augmenting laboratory experiments because of its advantages in detailing macro- and micro-mechanical information. However, it should be noted that the DEM does not usually consider the convergence for each time step, because of the necessity for a huge calculation time. In that case, it indicates that the uniqueness of the solution is not guaranteed, except in the case of a very small strain rate, even though the behavior looks qualitatively reasonable. At first, the influence of strain rate among numerically imaginary input parameters for a non-cohesive material was investigated for monotonic, biaxial shear tests. Then, new findings were obtained from the DEM simulations. Strain rate has a significant influence on the shear behavior, especially after the peak strength of dense specimens. A quasi-static steady state exists, not a static steady state. The “strong” fabric ratio is closely related to the stress ratio. The maximum slip coordination number occurs around the phase-transformation ratio and the shear band appears around the peak strength.
Ključne besede: discrete element method, DEM, induced anisotropy, quasi-static steady state, strain rate, uniqueness
Objavljeno: 14.06.2018; Ogledov: 426; Prenosov: 45
.pdf Celotno besedilo (690,97 KB)
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6.
Experimental research on variation of pore water pressure in constant rate of strain consolidation test
Hojjat Ahmadi, Hassan Rahimi, Abbas Soroush, Claes Alén, 2014, izvirni znanstveni članek

Opis: Constant rate of strain (CRS) consolidation is a rapid test method which is used for determination of compressibility of clayey soils. In a CRS test, the appropriate strain rate is selected based on pore water pressure ratio, i.e. the ratio of pore pressure to total stress. In the present study, to investigate the effect of strain rate on variation of pore water pressure ratio, four different clay samples of different plasticity were tested by CRS apparatus. The results of the experiments showed that the trend of variation of pore water pressure is dependent on the drained water flow regime which may be either Darcy or non-Darcy. The results also indicated that the plasticity of clay does not have considerable effect on variation of pore water pressure.
Ključne besede: constant rate of strain, consolidation, pore water pressure ratio, soil plasticity, Darcy and non-Darcy flow
Objavljeno: 14.06.2018; Ogledov: 362; Prenosov: 35
.pdf Celotno besedilo (576,58 KB)
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7.
A comparison between conventional triaxial and plane-strain compression on a particulate system using 3D DEM
Mahmud Sazzad, Kiichi Suzuki, 2012, izvirni znanstveni članek

Opis: Granular materials such as sand are subjected to different stress paths depending on the in-situ conditions. For example, a granular system under the foundations experiences conventional triaxial compression (CTC), while it experiences plane-strain compression (PSC) in the case of the embankment of roads. Due to the difference in the stress paths, the behavior of granular materials also becomes different. This paper aims at comparing the behavior of granular materials under CTC and PSC conditions using the 3D discrete-element method (DEM). An isotropically compressed dense sample consisting of 8000 spheres was prepared numerically using periodic boundaries. The CTC and PSC tests were simulated using the same isotropically compressed dense sample to compare and explore the macro- and micro-mechanical responses of granular materials without any bias from the initial fabric of the numerical sample. Qualitatively, the simulated stress-strain responses are consistent with that observed in the experimental studies. The dilatancy index is found to be independent of the stress paths used in the present study. The b value (defined as b = (σ2 − σ3)/(σ1 − σ3) where σ1, σ2 and σ3 are the stresses in the x1 -, x2 - and x3 - directions, respectively) - axial strain curve has a close similarity with the stress ratio - axial strain curve for the PSC test. The evolution of the coordination number and the sliding contact fraction is independent of the stress paths. A link between the macro- and micro-quantities is observed and a unique macro-micro relationship is noticed, regardless of the stress paths applied in this study.
Ključne besede: conventional triaxial compression, plane-strain compression, micro response, DEM
Objavljeno: 13.06.2018; Ogledov: 538; Prenosov: 43
.pdf Celotno besedilo (257,70 KB)
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8.
Measurement and interpretation of the small strain stifness of Boštanj silty sand
Gregor Vilhar, Vojkan Jovičić, 2009, izvirni znanstveni članek

Opis: This paper presents measurements, and an interpretation of these measurements, based on the use of bender-element probes for Boštanj silty sand. The samples were prepared at different initial void ratios and isotropically compressed up to 5 MPa. The bender-element technique was used to determine the dynamic shear modulus ($G_0$) of the soils at very small strains. The multiple bender-element probes were shot at different excitation frequencies in order to increase the reliability of the measurements. The $G_0$ stiffness was determined by using three different techniques: a) the first-time arrival, b) the phase-change method and c) the cross-correlation method. The systematic differences observed between the $G_0$ values, calculated using the three techniques, are discussed. The variation of $G_0$ in the log$G_0$ - log$p'$ plane was evaluated for the Boštanj silty sand and compared with other sands.
Ključne besede: silty sand, triaxial testing, small strain stiffness, bender elements, time-domain and frequency-domain, measurements
Objavljeno: 06.06.2018; Ogledov: 457; Prenosov: 36
.pdf Celotno besedilo (706,26 KB)
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9.
Prediction of the pile behaviour under dynamic loading using embedded strain sensor technology
Andrej Štrukelj, Mirko Pšunder, Helena Vrecl-Kojc, Ludvik Trauner, 2009, izvirni znanstveni članek

Opis: A standard dynamic loading test of the pile was performed on the highway section Slivnica - Hajdina near Maribor, Slovenia. Parallel to standard testing procedures the new monitoring technology based on specially developed strain sensors installed inside the pile body along the pile axis was introduced. On the basis of the measured results the normal strains along the pile axis were measured. Taking into consideration the elastic modulus of the concrete the normal stresses in the axial direction of the pile were also calculated and afterwards the shear stresses along the pile shaft have been estimated as well as the normal stresses below the pile toe. The estimation was made by considering a constant value for the pile diameter. The measured results were also compared with the computer simulation of the pile and the soil behaviour during all the successive test phases. The strain measurements inside the pile body during the standard dynamic loading test in present case did not have the purpose of developing an alternative method of pile loading tests. The presented monitoring technology proved itself as a very accurate and consistent. It gave in the first place the possibility of a closer look at the strains and stresses of the most unapproachable parts of different types of concrete structure elements especially piles and other types of deep foundations.
Ključne besede: piles, deep foundations, dynamic loading test, strain measurement technologies, elasto-plastic modelling, finite-element method
Objavljeno: 06.06.2018; Ogledov: 446; Prenosov: 47
.pdf Celotno besedilo (780,04 KB)
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10.
Modeling of the stress-strain behavior in hard soils and soft rocks
Vladimir Vukadin, 2007, izvirni znanstveni članek

Opis: The paper begins with a definition of hard soils and soft rocks (HSSR); this is followed by a short overview of the typical stress-strain behavior of HSSR. It is shown that in spite of the differences in the origin, type and strength of materials, similar stress-strain behaviors can be observed for different materials, ranging from soils to rocks. Based on this observed similarity a theoretical framework can be postulated, with which an appropriate constitutive model for HSSR can be formulated. This model includes the concepts of structure and destructurization as intrinsic material properties. A model named S_BRICK that takes into account the structure and destructurization has been developed and a comparison of this model’s predictions with laboratory results is presented.
Ključne besede: geomechanics, soft rocks, hard soils, stress-strain behaviour, constitutive modeling, structure, destructurization, numerical modeling
Objavljeno: 18.05.2018; Ogledov: 569; Prenosov: 50
.pdf Celotno besedilo (679,21 KB)
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