SCIDAR - Дигитална архива Универзитета у Крагујевцу
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ELEVATIONAL EARTH-SHELTERED BUILDINGS WITH HORIZONTAL OVERHANG PHOTOVOLTAIC-INTEGRATED PANELS – NEW ENERGY-PLUS BUILDING CONCEPT IN THE TERRITORY OF SERBIA
Full text linkThe global scientific community is intensively promoting energy-plus buildings. Following the leading world trends, this paper presents a new energy-plus building concept—elevational earth-sheltered buildings with three different types of horizontal overhang photovoltaic-integrated panels: wooden support columns covered with clay tiles, steel pipes as support columns covered with sheet steel, and concrete support columns with concrete coverage. In this instance, the specific multi-numerical case study building model for the city of Kragujevac (located in central Serbia with favorable climatic conditions) was performed over 7 months (from 1 October to 30 April), taking into account the soil temperature, the effects of solar shading, the performance of the heating system—a ground source heat pump, and the characteristics of the artificial and automatic lighting control system. The simulation results show that the optimal depth of a horizontal overhang (energy-plus status) depends on the occupant’s habits, in addition to meteorological conditions. The presented methodology can be used for any other location, both in Europe and the world.Publishe
Potential of contemporary earth-sheltered buildings to achieve Plus Energy status in various European climates during the heating season
No full textThis study investigates the potential of contemporary Earth-Sheltered Buildings to contribute tosustainable societies by achieving Plus Energy Building status during the heating season. Thebuildings analyzed are intended to house a four-member family (102.5 m2). The house is equippedwith a Ground Source Heat Pump, Geothermal Vertical Probes, Floor Heating Panels, an EnergyRecovery Ventilator, and Building-Integrated Photovoltaic panels installed on the exposedbuilding wall.The numerical analysis (using EnergyPlus software) was carried out for nine European sitescovering five different climatic zones (namely: southern, Atlantic, continental, alpine, and northernclimate) and three latitude belts spanning Europe from south to north.Buildings above 65°N (northern and alpine climate) could not achieve plus energy status with 20%efficient BIPVs. With 15% efficient BIPVs, building above 59°N (northern climate) was incapableof achieving this as well. Regarding the monthly time step, the buildings in the southern andAtlantic climates with 15% efficient BIPVs were able to produce an energy surplus every month,as was the building in the Alps with 20% efficient BIPVs.Publishe
Effects of Limiting the Number of Different Cross-Sections Used in Statically Loaded Truss Sizing and Shape Optimization
Full text linkThis research aims to show the effects of adding cardinality constraints to limit the number
of different cross-sections used in simultaneous sizing and shape optimization of truss structures. The
optimal solutions for sizing and shape optimized trusses result in a generally high, and impractical,
number of different cross-sections being used. This paper presents the influence of constraining the
number of different cross-sections used on the optimal results to bring the scientific results closer to
the applicable results. The savings achieved using the cardinality constraint are expected to manifest
in more than just the minimization of weight but in all the other aspects of truss construction, such
as labor, assembly time, total weld length, surface area to be treated, transport, logistics, and so on.
It is expected that the optimal weight of the structures would be greater than when not using this
constraint; however, it would still be below conventionally sized structures and have the added
benefits derived from the simplicity and elegance of the solution. The results of standard test examples
for each different cardinality constraint value are shown and compared to the same examples using
only a single cross-section on all bars and the overall optimal solution, which does not have the
cardinality constraint. An additional comparison is made with results of just the sizing optimization
from previously published research where authors first used the same cardinality constraint.Publishe
Koncesivne klauze u administratvno-pravnom stilu srpskoga jezika 19. veka
No full textCilj rada jeste ispitivanje statusa koncesivnih klauza u
administrativno-pravnom stilu srpskoga jezika 19. veka. Za korpus su
uzeti ustavi doneti u periodu od 1838. do 1901. godine, kao i zakonski
tekstovi u okviru Zbornika zakona i uredbenih ukaza za Kneževinu
(Kraljevinu) Srbiju. Nakon izvršene semantičko-sintaksičke i funkcionalnostilske analize, utvrdili smo da koncesivne klauze čine marginalni sloj zavisnosloženih rečenica u korpusu. Potvrđene su klauze i sa opštekoncesivnim i sa parcijalnokoncesivnim značenjem. Koncesivnim
klauzama iskazuje se ono što je hijerarhijski sekundardno i manje važno
s aspekta normativnopravnog teksta. Od parcijalnokoncesivnih veznika primećeni su subjekatskokoncesivni, kvalitativnokoncesivni, kvantitativnokoncesivni i lokacionokoncesivni tip. Upotrebljavaju se dva tipa složenih parcijalnokoncesivnih veznika: složeni veznici sa partikulom god u postpoziciji i složeni veznici sa partikulom mau prepoziciji. Parcijalnokoncesivni veznici ukazuju na to da zakonski propis važi bez obzira na to što je jedan segment stvarnosti (najčešće krivac) relativizovan.Publishe
Advancing students’ achievements in multivariable calculus education through CSCL
Full text linkThe contents of calculus, known for their complexity, present significant challenges for students, particularly in
mastering multiple integrals and effectively visualizing related concepts. The transition to distance learning
prompted by the COVID-19 pandemic has further complicated the learning process in multiple integrals. In line
with this and considering the potential of computer-supported collaborative learning (CSCL), in this research we
explore the impact of teaching in a CSCL environment on student achievements, focusing on students from the
computer science study program. Through data analysis using ANOVA and Bonferroni post-hoc tests, it was found that students exposed to collaborative learning in GeoGebra environment demonstrated higher levels of
theoretical and practical knowledge compared to peers who acquired knowledge without using GeoGebra.
Additionally, this group of students achieved results comparable to those of students who attended traditional in person teaching, showing noticeable improvements in solving complex tasks. Our findings show the effectiveness of CSCL approach in context of distance learning and highlight potential of collaborative environments enhanced with technology in facilitating student understanding and achievements in calculus education.https://www.iejme.com/download/advancing-students-achievements-in-multivariable-calculus-education-through-cscl-14472.pdfPublishe
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ANTITUMOR EFFECTS OF TANACETUM BALSAMITA ESSENTIAL OILS BY DOWNREGULATION NRF-2 AND MMP-9 IN BREAST CANCER
Full text linkThe aim of this study was to investigate antitumor capacity of different Tanacetum balsamita essential oils by measuring apoptosis rate, MMP-9 concetration and Nrf-2 expression level in human MBA-MB-468 and MDA-MB-231 cells. The tested EOs expressed proapoptotic effects, significantly inhibited the MMP-9 concentration and down-regulated the expression level of Nrf-2. The obtained data suggest that the tested EOs exert considerable antitumor activity elevating apoptosis level and inhibiting the motility of tested cancer cells. The reduced levels of Nrf-2 expression suggest decreased defense potential for oxidative disturbances, which could be the major antitumor mechanism detected in the study.Publishe
HEALTH SAFETY OF BAKERY PRODUCTS
Full text linkNutrition is the main factor in people’s health. Food can be both a resource and a great hazard to the health of the entire population. The Institute for Public Health Kragujevac is an accredited institution for food analysis. In 2023, 472 samples of bakery products were sampled and analyzed; 469 products (99.36%) were microbiologically safe and 460 products (97.45%) were chemically compliant. The increased yeast content was the microbiological reason for the unsoundness of the two bakery products. Recommended measures: to increase the scope of testing in both microbiological and chemical aspects, by supplementing the current regulations.Publishe
OPTIMAL SIZE AND POSITION OF THE PLANAR BACK REFLECTOR MOVEABLE ONLY IN THE DIRECTION NORMAL TO THE BIFACIAL SOLAR COLLECTOR PLANE
Full text linkIn this paper, the concept of a collector-reflector system consisting of a bifacial solar collector and a single flat-plate reflector separated and placed in parallel below the collector but moveable only in the direction normal to the collector plane is investigated. The developed mathematical model was used to optimize the size and position of the planar back reflector. The optimal hourly, daily, monthly and annual distances between the collector and reflector were determined. In addition, the daily, monthly and annual energy performance of the optimized bifacial collector-reflector system was estimated and compared with that of the corresponding monofacial solar collector. Based on the obtained results, two ways of use of the reflector are recommended, either according to the optimal hourly (moveable reflector) or optimal annual (fixed reflector) reflector positions. With optimally positioned moveable or fixed reflector the total solar radiation incident on the bifacial solar collector can be significantly higher than that for a monofacial solar collector. Its largest daily and monthly as well as average annual increase is: 74% (59%), 65.91% (46.21%) and 54% (39.4%), respectively. The proposed model can be applied to evaluate the energy performance of flat-plate bifacial thermal, photovoltaic or photovoltaic-thermal solar collector, of arbitrary size and position, which is in this arrangement with a planar reflector
On Null Cartan Rectifying Isophotic and Rectifying Silhouette Curves Lying on a Timelike Surface in Minkowski Space
Full text linkIn this paper, we introduce generalized Darboux frames of the first and the second kind alonga null Cartan curve lying on a timelike surface in Minkowski space E31 and define null Cartan
rectifying isophotic and rectifying silhouette curves in terms of the vector field that belongs to
generalized Darboux frame of the first kind. We investigate null Cartan rectifying isophotic and
rectifying silhouette curves with constant geodesic curvature kg and geodesic torsion τg and obtain
the parameter equations of their axes. We prove that such curves are the null Cartan helices and
the null Cartan cubics. We show that the introduced curves with a non-zero constant curvatures
kg and τg are general helices, relatively normal-slant helices and isophotic curves with respect to
the same axis. In particular, we find that null Cartan cubic lying on a timelike surface is rectifying
isophotic and rectifying silhouette curve having a spacelike and a lightlike axis. Finally, we give
some examples.https://dergipark.org.tr/en/pub/iejg/issue/84071/1447199Publishe