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Effect of particle roundness and morphology on the shear failure mechanism of granular soil under strip footing
Babak Karimi Ghalehjough, Suat Akbulut, Semet Çelik, 2018, izvirni znanstveni članek

Opis: This study investigates the effect of particles roundness and morphology on the shear failure mechanism of soil. A strip footing was modeled under laboratory conditions. Calcareous soil was tested with three roundness classes: angular, rounded and well-rounded shapes with sizes of 0.30 mm to 4.75 mm. These were divided into six different groups at three relative densities of 30%, 50% and 70%. A series of photographs was taken during the tests and analyzed using the particle image velocimetry (PIV) method to understand the soil-deformation mechanism. The results showed that increasing the sample sizes increased the affected area of the soil. At the same time, increasing the relative density caused a punching failure mechanism that went towards the general failure. The shear failure mechanism of the soil changed from general toward punching shear failure with increasing particle roundness. This effect was larger with the smaller materials. Underneath the affected layers of soil, the angular samples were deeper than the rounded and well-rounded samples. The affected depth in the angular soil was approximately 1.5B in the smallest size group. This was more than 3B and near 4B in the largest size group. Both the sides and the underlying soil layers should be considered on angular soils. The area under the footing becomes more important than the side parts after increasing the roundness of the particles.
Ključne besede: particle roundness, morphology of particles, shear failure mechanism, strip footing, PIV method, ultimate bearing capacity
Objavljeno: 11.10.2018; Ogledov: 681; Prenosov: 280
.pdf Celotno besedilo (701,47 KB)
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An unsaturated-soils approach to the bearing capacity of foundation structures
Taha Taskiran, 2017, izvirni znanstveni članek

Opis: Unsaturated soils are maintaining their importance for researchers and there is still much need to investigate the many engineering aspects of these soils. A new technique is proposed here to predict the variation of the bearing capacity of unsaturated soils with matric suction. The proposed method is an extension of conventional bearing-capacity theories and conceptually based on the logarithmic model of the shear strength of unsaturated soils, which only include one unknown, unsaturated parameter (the airentry value, AEV). The possibility of predicting the unsaturated bearing capacity of soils is shown by the saturated effective shear-strength parameters c' and Ø' and the AEV from the soil-water retention curve (SWRC). Considering the necessity of validating new methods with other researchers’ data, the proposed equation is tested using the published unsaturated experimental study by the author, in addition to some reported experimental studies on the shear strength for unsaturated soils and also a model footing loading on unsaturated sand under controlled suction conditions. The results of the study indicate that there is a good comparison between the “unsaturated bearing capacities” obtained via predicted and measured unsaturated strength parameters (ctotal , Ø) and also between the measured/ calculated bearing values of a model footing loading. Consequently, it is shown that, without needing complex unsaturated testing facilities, the proposed equation is capable of predicting the unsaturated bearing capacity for both fine-grained and sandy soils, requiring only one unsaturated parameter, which can be obtained from the SWRC or predicted using the basic soil-index properties.
Ključne besede: unsaturated soils, unsaturated bearing capacity, suction strength, foundation design
Objavljeno: 18.06.2018; Ogledov: 433; Prenosov: 38
.pdf Celotno besedilo (347,24 KB)
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Critical setback distance for a footing resting on slopes
Rajesh Prashad Shukla, Ravi Sankar Jakka, 2017, izvirni znanstveni članek

Opis: Structures are often constructed on slopes in hilly regions, which results in a lack of soil support on the sloping side of the footings. This causes a reduction in the bearing capacity of the footings. Though there are number of studies about foundations on slopes, most of these studies are confined to surface footings only (i.e., without the depth of embedment). Furthermore, there is no consensus in the literature over the influence of the setback distance on bearing capacity. This paper presents the results of finite-element analyses on a strip footing resting on stable slopes. A very large number of possible soil slopes with different footing depths were analysed. From the results it is found that the critical setback distance increases with an increase in the internal friction angle of soil, the depth of the footing and the slope gradient. The critical setback distance is varying between 2 to 4 times the footing width for soils with a low internal friction angle, while it is more than 10 times the footing width for soils with a higher internal friction angle. A regression equation is also developed based on the outcomes of the study. The developed equation is able to predict the influence of various parameters affecting the bearing capacity of a footing resting over the slopes. The results are compared with earlier experimental and numerical studies.
Ključne besede: bearing capacity ratio, cohesionless soil, footing, setback distance, slopes
Objavljeno: 18.06.2018; Ogledov: 499; Prenosov: 51
.pdf Celotno besedilo (1,53 MB)
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Geo-information technology for disaster risk assessment
Đorđe Ćosić, Sađan Popov, Dušan Sakulski, Ana Pavlović, 2011, izvirni znanstveni članek

Opis: The Serbian territory (including the territory of the former Yugoslavia) has been continuously exposed to different hazards, often with tragic consequences. Earthquakes and floods, usually followed by landslides, are the most dominant hazards in that region. Disaster risk reduction, prevention and early warning, as an integral part of sustainable development, do not exist in Serbia. That is one of the main reasons why the disaster-related damage is high. Despite very long experience in engineering and resources management in Serbia, there are no scientifically supported and standardized disaster risk-assessment procedures. Expertise only exists in the field of engineering-based hazard assessment. The risk-assessment method proposed in this research includes, apart from hazards, parameters such as vulnerability, exposure and safety. It considers the environmental and social components of risk management. The proposed method, implementing combined mathematical and 3D GIS tools, was applied for the Danube River, Petrovaradin (the city of Novi Sad) area, for which data were available. The relationship between the risk parameters is calculated and graphically presented. Methods like this one should contribute to a shift from a passive disaster-related defense to a proactive disaster risk management, as well as from emergency management only, to disaster prevention, preparedness and mitigation activities, in Serbia and the Western Balkan Region.
Ključne besede: hazard, vulnerability, safety, resilience, coping capacity, risk assessment, risk management, geographic information systems, earthquake, landslide, flooding, exceedance
Objavljeno: 13.06.2018; Ogledov: 367; Prenosov: 37
.pdf Celotno besedilo (418,04 KB)
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Suggestion about determination of the bearing capacity of piles on the basis of CPT sounding tests
József Pusztai, 2005, izvirni znanstveni članek

Opis: The Cone Penetration Test (CPT) is a well-recognized tool for the calculation of the ultimate bearing capacity of piles. Within the Hungarian physiographic territory, the CPT and Static Pile Load Tests of the bored (Continuous Flight Auger - CFA, protective tube) and driven (Franki) piles installed in different soils (gravel, sand and clay) were compared to determine the ultimate bearing capacity of piles by using new formulae.
Ključne besede: bearing capacity of piles, cone penetration test
Objavljeno: 15.05.2018; Ogledov: 529; Prenosov: 37
.pdf Celotno besedilo (155,29 KB)
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The influence of organizational absorptive capacity on product and process innovation
Nika Murovec, Igor Prodan, 2008, izvirni znanstveni članek

Opis: The innovativeness of an organization has an important impact on its profitability as well as on the competitiveness of a country's economy as a whole. Since the innovativeness of Slovenian organizations is low, it is important that managers and industrial policy makers know which factors influence an organizations' innovation. One of these factors is supposed to be the organizational absorptive capacity. Absorptive capacity is one of the most important concepts that have emerged in the field of organizational research in the past years. Absorptive capacity is defined as the set of organizational routines and processes through which an organization identifies and values new external information, and then acquires it, assimilates it and applies it to commercial ends. The results of this research confirm the strong and positive impact of Slovenian organizations' absorptive capacity on process innovation and the even bigger positive influence on the organizations' product innovation.
Ključne besede: innovation, innovativeness, absorptive capacity, enterprises, structural equation modelling, Slovenia
Objavljeno: 22.01.2018; Ogledov: 477; Prenosov: 279
.pdf Celotno besedilo (284,64 KB)
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Nostalgia, commodification of emotions and small-town tourism
Barbara Pavlakovič, Nejc Pozvek, Andreja Trdina, 2016, objavljeni znanstveni prispevek na konferenci

Opis: Small urban environments face many issues in tourism; for example, how to position themselves in contrast to the larger cities and how to provide adequate tourist facilities for their guests. In the case of positioning, they have to choose something different and attractive. And in the case of infrastructure, small cities are primarily meant for their residents and have plenty residential buildings but lack of tourist accommodation buildings. The article attempts to reflect on specific contemporary form of “consumed nostalgia” (Cross, 2015) that is characteristic of the era of modern consumer society and offer an example of how its potential could be employed in tourism, particular in small urban environments with significant implications of preserving abandoned properties and thus existing architectural and cultural heritage. An analysis of Vintage Vila accommodation facility that is located in small city of Brežice, Slovenia, was conducted in order to acquaint the potential of a specific form of nostalgia tourism. After an interview with Vintage Vila founder, a review of their Facebook site and the responses of the visitors was made. Additionally the study of media coverage of Vintage Vila was completed to understand the discursive construction of a unique narrative of the place. The basic objective of this paper is to describe this innovative solution for the preservation of architectural and cultural heritage of small urban environments. With the case study of Vintage Vila accommodation facility we hope to encourage other small cities to recognise their potential in abandoned buildings. Restoration of such facilities can open up new possibilities in tourism and may, together with thoughtfully chosen narratives that emotionally bound people to their material environment, contribute to a revitalization of small cities. What is more, tourism development grounded in vintage and nostalgia appeals should be considered as part of a call for sustainable growth, as it advocates and supports alternative consumer practices (such as recycling and reusing objects) and preservation of material culture in general.
Ključne besede: nostalgia tourism, vintage, accommodation capacity, small urban environments, place as a narrative
Objavljeno: 03.11.2017; Ogledov: 922; Prenosov: 83
.pdf Celotno besedilo (868,77 KB)
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Analytical and numerical factor of safety (uls) calculations on reinforced embankments
Tadej Vidnar, 2017, magistrsko delo

Opis: This thesis deals with factor of safety calculations on geogrid reinforced embankments carried out by commonly used limit equilibrium (LEM) and finite element methods (FEM). The study utilize LEM based software SLIDE and FEM based software PHASE2. The main difference between these two approaches is that the LEM methods are based on the static of equilibrium whereas FEM methods utilise the stress strain relationship. Unlike to LEM, numerical analysis also computes displacements. For practical example of a geogrid reinforced embankment the factor of safeta (FoS) is calculated. Reinforced soil structures are nowadays utilized for a lot of civil engineering applications. Traditionally, the design of geogrid reinforced soil is performed using analytical methods (LEM). Unfortunately, these methods missing the fundamental physics of stress-strain relationship and are therefore not able to compute a realistic stress distribution. In first step of the analysis the FoS is carried out with analytical approach. The most rigorous LEM methods, Bishop’s, Spencer’s and Morgenstern-Price are selected and the FoS for circular and polygonal slip surface is calculated. In second step of the analysis the FoS is carried out with numerical approach. Shear strength reduction (SSR) procedure was performed to determine the critical strength reduction factor (SRF) which represents the FoS of slope.
Ključne besede: civil engineering, finite element method (FEM), limit equilibrium method (LEM), embankments, slope stability, bearing capacity failure, geosynthetics, geogrids, shear strains
Objavljeno: 27.09.2017; Ogledov: 583; Prenosov: 123
.pdf Celotno besedilo (17,05 MB)

Homecare service providers as an organizational form of support for the elderly
Polona Šprajc, Iztok Podbregar, Alenka Brezavšček, 2017, izvirni znanstveni članek

Opis: Background and Purpose: Different studies have highlighted health care allocation problems in Slovenia that indicate the increased need for homecare services for the elderly. It was also found that Slovenian municipalities differ dramatically in the availability of elder care services. A number of older people with diverse unmet needs for care remains. Therefore, the need for the establishment of an additional type of formal homecare services for the elderly exists. Design/Methodology/Approach: Although many positive effects of home elder care against institutional care are stressed in the literature, the results of many studies performed in recent years have indicated that accessibility of homecare for elderly in Slovenia remains scarce, and it is not equally accessible throughout the country. To mitigate this problem, a new organizational form called “elder homecare service provider” is indicated. The aim of the provider is to offer a variety of different services for the elderly (e.g. homemaking, social networking, transfer services, basic life needs, basic health services, etc.). The establishment of such an organization needs to be designed carefuly, while the unique characteristics and specific needs of the target population must be addressed to optimize desired outcomes. Results: The aim of the paper is to provide fundamental guidelines for the establishment of elder homecare service provider. All essential characteristics of such an organization are defined. To ensure an appropriate level of service quality, the primary focus is oriented towards the planning of personnel team capacity. For this purpose, the service provider was described using the stochastic queueing model, which enables service capacity optimization considering different performance measures. The usefulness of the model was illustrated with a numerical example, which has shown that the results obtained provide valuable information for decision support. Conclusion: The establishment of a homecare service provider network would have many positive effects on society in general. The quality of the everyday life of the elderly is expected to be improved considerably, particularly in the rural areas where a lack of institutional care support is reported. Guidelines proposed in the paper together with the quantitave model for planning of its optimal capacity provide useful information, which are especially relevant in the preliminary phase of the establishment of service providers.
Ključne besede: elderly, service provider, performance measures, capacity planning
Objavljeno: 01.09.2017; Ogledov: 613; Prenosov: 112
.pdf Celotno besedilo (569,19 KB)
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The role of brain oscillations in working memory
Anja Pahor, 2017, doktorska disertacija

Opis: Working memory is important for a number of higher cognitive functions such as problem solving, reasoning, reading and language comprehension. Moreover, working memory measures are significantly correlated with measures of intellectual abilities. Investigating the neural basis of working memory provides the opportunity to gain a deeper understanding of individual differences in general cognitive ability. This thesis aimed to elucidate the roles of brain oscillations in working memory, with a particular focus on theta and gamma frequency bands. Two techniques were employed that are best suited for the non-invasive study of brain oscillations: scalp recorded EEG and transcranial alternating current stimulation (tACS). In the first step, correlational studies were conducted followed by neuromodulatory studies in the next step. The results showed that individuals with high working memory capacity, contrasted against individuals with low working memory capacity, display stronger alpha and gamma band desynchronisation and increased coherence in the theta frequency band between fronto- parietal areas during maintenance and between frontal brain areas during retrieval. The results further demonstrated that interactions between theta and gamma frequency bands are related to individual differences in working memory capacity. The neuromodulatory studies showed that theta tACS applied over parietal brain areas can be used to enhance performance on working memory tasks, thereby providing support for the causal role of theta band oscillations in working memory.
Ključne besede: working memory, brain oscillations, capacity, electroencephalograpy, tACS, theta, gamma
Objavljeno: 28.07.2017; Ogledov: 1009; Prenosov: 106
.pdf Celotno besedilo (3,46 MB)

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