In the realm of injection-molded parts, small length scale deformation defects such as sink marks often pose a major challenge to the aesthetics or functionality of the parts. To address this ...problem, we present a comprehensive thermoelastomechanical approach that calculates the deformation of injection molded plastic by solving the elastic problem at each time step. In our methodology, two treatments of the molten core are considered: one as a liquid and the other as a rubbery state. Our results suggest that the rubbery state treatment provides higher accuracy in predicting the deformation results, as it maintains the displacement of the localized thermal shrinkage in its vicinity. The validity of our method is supported by empirical measurements on produced parts from the existing literature as well as on samples that we molded independently.
The article reviews the development and interpretation of procedures used in the study of the sedimentary sequence of the Divje babe I Palaeolithic cave site. The data were obtained from ...publications, archives, and personal information provided by Ivan Turk, who directed the excavations and directed the laboratory investigations. The profile of Divje babe I is currently the best researched and chronologically defined Late Pleistocene cave profile in Slovenia. For the first time, various sedimentological and other data from the standard profile were upgraded with the same data obtained on standardized ground plan surfaces and depths. A large spatial (lateral) variability was discovered, associated with generally contemporaneous but different cave microenvironments, which were crucially influenced by different amounts of water in all aggregate states. Without taking into account temporal and spatial dimensions, it would not be possible to combine all statistical sets of collected data on sediments, their contents, and climatic parameters into a unified system.
The CO
2
concentration of the air in Postojna Cave (400–7900 ppm) is found to be induced by CO
2
sources (human respiration contributing ~ 20,000–58,000 ppm per breath, outgassing of dripwater and ...water seeping from the vadose zone/epikarst with a
p
CO
2
values of 5000–29,000 ppm, and underground Pivka River having
p
CO
2
at 2344–4266 ppm) and CO
2
dilution (inflow of outside air with a CO
2
concentration of ~ 400 ppm). Measurements show that sinking Pivka River has the lowest CO
2
concentration among plausible CO
2
sources but still continuously exceeds the surrounding cave air CO
2
concentration. During the winter months, intensive ventilation reduces the cave air CO
2
concentration to outside levels (~ 400 ppm), even in the centre of the cave system. CO
2
dilution is less pronounced in summer (CO
2(min)
≈ 800 ppm), since the ventilation rate is not as strong as in winter and the outside air that enters the cave through breathing holes and fractures is enriched with soil CO
2
. During spring and autumn, the daily alternation of the ventilation regime with a smaller rate of air exchange results in yearly cave air CO
2
peaks of up to ~ 2400 ppm. Some dead-end passages can be much less affected by ventilation, resulting in a cave air CO
2
concentration of up to 7900 ppm. The strongest diurnal CO
2
peaks due to human respiration were recorded during the spring holidays (increase of up to 1300 ppm day
−1
), compared to considerably smaller summer peaks despite peak visits (increase of ~ 600 ppm day
−1
).
Historical air temperatures at three karst caves in Slovenia have been compared to current data time series. In Postojnska Jama (PJ), the most visited show cave in Slovenia, the significant ...temperature difference between historical and modern measurements at the Pulpito site relates to the months April to November. Mean monthly temperatures measured at the Sepolcro site (PJ) in the modern period (2016–2019) are year round significantly higher than in the historical period (1935–1937). The temperature increase over the last 85 years in PJ is attributed to outside temperature rise and additional heat input from visitors, especially for Sepolcro site. A comparison of current (2017–2019) and historical (1956–1957) temperature data in touristically poorly visited Predjama Cave shows lower increase as in PJ and is completely related to outside cave conditions. In the case of Škocjanske Jame (Tiha Jama), air temperature has not significantly increased since the historical 1928 measurements because the monitoring site looks to be morphologically isolated from significant impacts of outside climate and visitors.
This research explores sustainable construction practices focusing on material reuse, specifically reclaimed structural steel and slag. In general, the building stock is not designed for ...deconstruction, and material recovery for reuse at the end of life of buildings is complex and challenging. The study evaluates the benefits of content reuse through a thorough analysis of three case studies—BedZED eco-friendly housing, Angus Technopôle building, and the use of steel slag aggregate in road construction. It highlights the value of reclaimed structural steel and by-products like steel slag in waste reduction, energy conservation, and resource preservation. The BedZED case study showcases recycled steel’s cost-effectiveness and economic viability in construction, while the Angus Technopôle building exemplifies the adaptive reuse of an old steel frame building. Additionally, the third case study showcases the benefits of using Electric Arc Furnace C slag in asphalt-wearing courses, highlighting the reduction in greenhouse gas emissions and environmental impact. The versatility of reclaimed structural steel and slag is evident in integrating material reuse in building construction and road infrastructure. These case studies illustrate the potential for reusing steel and its by-products in various construction contexts, from eco-friendly housing to road development. Therefore, the study aims to demonstrate the feasibility and benefits of sustainable practices within the construction industry by showcasing the successful incorporation of reclaimed steel and slag in these projects. Considering the significant contributions of building construction to global greenhouse gas emissions, raw material extraction, and waste production, the study advocates for adopting circular economy (CE) principles within the construction industry. Finally, the analysis of case studies underscores the advantages of reclaimed structural steel and the valorisation of steel slag through the lens of CE and their contribution to sustainable development.
Alkali-activated foams (AAFs) are inorganic porous materials that can be obtained at temperatures well below 100°C with the use of inorganic wastes as aluminosilicate precursors. In this case, fly ...ash derived from a Slovenian power plant has been investigated. Despite the environmental benefits
, due to saving of energy and virgin materials, when using waste materials, it is of extreme importance to also evaluate the potential leaching of heavy metal cations from the alkali-activated foams. This article presents an environmental study of a porous geopolymer derived from this particular fly ash, with respect to the leachability of potentially hazardous elements, its environmental toxicity as determined by biological testing, and the environmental impact of its production. In particular, attention was focused to investigate whether or not 1,000°C-fired alkali-activated fly ash and metakaolin-based foams, cured at 70°C, are environmentally friendlier options compared to unfired ones, and attempts to explain the rationale of the results were done. Eventually, the firing process at 1,000°C, apart from improving technical performance, could reinforce heavy metal cation entrapment within the aluminosilicate matrix. Since technical performance was also modified by addition of different types of activators (K-based or Na-based), as well as by partial replacement of fly ash with metakaolin, a life cycle assessment (LCA) analysis was performed to quantify the effect of these additions and processes (curing at 70°C and firing at 1,000°C) in terms of global warming potential. Selected samples were also evaluated in terms of leaching of potentially deleterious elements as well as for the immobilization effect of firing. The leaching test indicated that none of the alkali-activated material is classified as hazardous, not even the as-received fly ash as component of new AAF. All of the alkali-activated foams do meet the requirements for an inertness. The highest impact on bacterial colonies was found in samples that did not undergo firing procedures, i.e., those that were cured at 70°C, which induced the reduction of bacterial
viability. The second family of bacteria tested,
, appeared more resistant to the alkaline environment (pH = 10-12) generated by the unfired AAMs. Cell viability recorded the lowest value for unfired alkali-activated materials produced from fly ash and K-based activators. Its reticulation is only partial, with the leachate solution appearing to be characterized with the most alkaline pH and with the highest ionic conductivity, i.e., highest number of soluble ions. By LCA, it has been shown that 1) changing K-based activators to Na-based activators increases environmental impact of the alkali-activated foams by 1%-4% in terms of most of the impact categories (taking into account the production stage). However, in terms of impact on abiotic depletion of elements and impact on ozone layer depletion, the increase is relatively more significant (11% and 18%, respectively); 2) replacing some parts of fly ash with metakaolin also results in relatively higher environmental footprint (increase of around 1%-4%, while the impact on abiotic depletion of elements increases by 14%); and finally, 3) firing at 1,000°C contributes significantly to the environmental footprint of alkali-activated foams. In such a case, the footprint increases by around one third, compared to the footprint of alkali-activated foams produced at 70°C. A combination of LCA and leaching/toxicity behavior analysis presents relevant combinations, which can provide information about long-term environmental impact of newly developed waste-based materials.
The sub-surface flow path through the Postojnska jama cave system has been monitored with 7 stations distributed along the flow path, monitoring stage and temperature. We have used the stage data to ...model flow through the cave system with the program package SWMM, simulating the active parts of Postojnska jama with simplified geometry. From the comparison of stage observations and predictions, we identified key sections in the cave, which control the sub-surface flow, such as passage constrictions, sumps and by-passes. Using a formal inverse procedure, we determined the geometry of this key sections by fitting predicted to observed stages, and we achieved a very high degree of correlation. Key words: modelling, hydrology, Postojnska jama. Modeliranje toka podzemeljske Pivke v Postojnski jami, Slovenija Z avtomatskimi merilniki in registratorji podatkov smo spremljali podzemni tok Pivke v Postojnski jami na sedmih točkah med ponorom in odtočnim sifonom v Pivki jami. Podatke nivojev in pretoka smo obravnavali z modelom EPA SWMM, s katerim smo simulirali tok v poenostavljeni geometriji kanalov. S primerjavo med opazovanji in modelskimi rezultati smo določili ključne odseke (podore, zožitve, sifone, obtoke), ki najbolj vplivajo na dinamiko toka podzemne Pivke. Glavne parametre teh odsekov smo določili z inverzno metodo, ki temelji na algoritmu soseske (Neighbourhood algorithm, NA) in pri tem dobili odlično ujemanje med modelom in podatki. Ključne besede: modeliranje, hidrologija, Postojnska jama.
Cave sediments are more protected from weathering, erosion and other exogenic processes in comparison with sediments that accumulate at the Earth’s surface. For this reason, cave sediments keep a ...unique record of climate variations in the Pleistocene. Archaeological (Palaeolithic) sites, where sediments (including pollen, charcoal and bone fragments) can be systematically studied in one or several profiles, are the most useful for multidisciplinary surveys. Such surveys are very important for archaeologists because they offer insight into climate conditions that prevailed in the period when humans visited the cave and left various traces there. So-called geoarchaeological surveys demand extensive cooperation between archaeologists and geologists.
V članku obravnavamo rezultate arheoloških raziskav na najdiščih Črnelnik in Devce na Ljubljanskem barju v letu 2014. Gre za dve novoodkriti najdišči iz obdobja, ko so na Ljubljanskem barju živeli ...koliščarji. Na podlagi interdisciplinarnih analiz uvrščamo kolišče na Črnelniku na začetek 4. tisočletja pr. Kr. Manj podatkov je pridobljenih z najdišča Devce, zato njegov značaj še ni ugotovljen. Postavljamo ga v čas med 4. in 2. tisočletjem pr. Kr.
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