Machinery - Repository of the Faculty of Mechanical Engineering, University of Belgrade
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UREĐAJ ZA TERMIČKU PRIPREMU MIKROBIOLOŠKIH KULTURA POD DEJSTVOM TEMPERATURNOG GRADIJENTA DEVICE FOR THERMAL CONDITIONING OF MICROBIOLOGICAL SAMPLES BY TEMPERATURE GRADIENT
No full textУређај којим се врши термичка припрема микробиолошких култура тако што се
на радној плочи која је у контакту са микротитер плочом ствара и одржава
температурни градијент. Уређај се састоји од металног носача (1), вентилатора (2), (3),
хладњака (4), (5), термоелектричних Пелтијеових елемената (6), (7), алуминијумске
радне плоче (8), електричног кола (9) за мерење температуре, електричног кола (10) за
контролу температуре, мини-рачунара (11), електричног напајања (12), бежичне
тастатуре (13), компјутерског миша (14), компјутерског дисплеја (15), HDMI кабла (16),
micro USB кабла (17). Основни принцип рада уређаја је пренос топлоте кондукцијом са
алуминијумске радне плоче на микротитер плочу. Уређај омогућава in vitro испитивање
утицаја температуре на бактериолошке културе. Уређај остварује контролу температуре
у распону који је користан у већини биолошких испитивања (20–55 °C), преносив је,
може се лако серијски произвести јер се састоји од широко распрострањених
електронских компоненти и омогућава унапређење кроз развој програма за
мини-рачунар који је саставни део уређаја
Aspekti korišćenja biomase u cilju povećanja energetske efikasnosti i smanjenja emisije CO2
No full textБиомаса представља један од најзначајнијих обновљивих извора
енергије, пре свега због велике заступљености и разноврсности, као и значајног
енергетског садржаја. Осим шумске биомасе, велики део укупног потенцијала биомасе у Србији потиче од пољопривредне биомасе. Oд укупне количине
расположивог техничког потенцијала пољопривредне биомасе мали део се користи у енергетске сврхе. У индустрији прераде воћа и поврћа остају значајне
количине органског отпада, као што је воћни троп, који може представљати алтернативну сировину за добијање енергије, уз смањење емисијe гасова са ефектом стаклене баште. У овом раду извршено је истраживање оцене угљеничног
отиска животног циклуса на примеру органског отпада преосталог након процеса цеђења сока од јабуке (тзв. тропа), јер је јабука најкоришћеније воће за производњу сокова у Србији. Анализирани су енергетски, еколошки и економски
аспекти коришћења тропа јабуке као алтернативног енергента. Постоји значајан
потенцијал коришћења воћног тропа као еколошки прихватљивог горива за добијање топлотне енергије. Урађена је процена директног коришћења осушеног
тропа јабуке за повећање енергетске ефикасности реалног постројења за прераду воћа, као и индиректног коришћења за загревање пластеника. Коришћењем
тропа јабуке може се значајно смањити емисија еквивалентног CO2
(CO2
eq) у
односу на фосилна горива, као и трошкови снабдевања енергијом, с обзиром да
воћни троп представља нуспродукт процеса прераде воћа.Biomass represents one of the most important renewable energy sources
in Serbia, primarily due to its abundance and diversity and its high energy content. In addition to forest biomass, a very significant part of the total biomass
potential in Serbia comes from agricultural biomass. Currently, only a small part
of the available biomass potential is utilized as a renewable energy source. Large
amounts of organic waste are available from the fruit processing industry, such
as fruit pomace, which represents a promising raw material for obtaining energy while reducing greenhouse gas emissions. In this paper, the research was carried
out on the evaluation of the carbon footprint of the apple pomace life cycle since
the apple represents the most used raw material for juice production in Serbia.
The technical, energetic, ecological, and economic aspects of using apple pomace
as an alternative energy source were analyzed. The use of dried pomace was evaluated for improving energy efficiency of the existing industrial facility for fruit
processing and heating greenhouses. Using apple pomace can significantly affect
the reduction of CO2
(CO2eq) emission, compared to fossil fuels, as well as the reduction of energy costs, considering that the fruit pomace is a by-product in the
food processing industry
The Influence of Temperature Gradient on Thin Plates Bending
Get PDFWithin the theory of thermo-elasticity, the temperature field of thin plates
is commonly defined via two parameters: temperature in the mid-plane and
linear temperature gradient normal to the mid-plane. First, the paper
analytically proves the justification of that assumption in machine
structures. Then, in an analytical closed form, applying the integral
transformation method, the thin plate deflection caused by a constant
temperature gradient is defined. It is shown that, in that case, the plate
deflection does not depend on its thickness but only on the plate
dimensions in the mid-plane. Analytically defined values are compared to
corresponding values obtained by applying the thin plate finite element,
where the temperature field is described using the two mentioned
parameters. This finite element is defined and programmed within the
Komips program package. The influence of the temperature gradient on
the behavior of constructions mostly depends on the type of material. That
is why the behavior of some structural elements made of brass, steel, and
concrete is analyzed in this paper
Effect of Corrosion-Induced Structural Degradation on the Ultimate Strength of a High-Tensile-Steel Ship Hull
Get PDFStandard structural assessments of ship hulls include the evaluation of the elastic structural response. Elastic analysis neglects extreme and unpredicted loadings, which can produce catastrophic outcomes, such as the loss of the ship’s ultimate strength. Moreover, hull elements are considered unaffected by age-related degradation. Therefore, this study models and quantifies the effect of corrosion-induced structural degradation on the ultimate strength of a high-tensile-steel (HTS) cargo ship using progressive collapse and nonlinear finite element methods. Uniform and pitting corrosion are modeled through selected scenarios, which hull elements might encounter during exploitation, producing a total of 148 calculation models. The findings show that corrosion-induced degradation can significantly decrease the ultimate strength of the hull (up to 30% for the most severe scenarios assessed). Furthermore, ultimate strength decreases almost proportionally to the amount of wastage considered. It was found that stiffener corrosion has a significant effect on the total ultimate strength. This study’s aim is to emphasize the vast importance of including ultimate strength along with ageing effects in industry-standard structural assessments of large HTS ship structures, designed to last for several decades whilst exposed to excessive and unpredicted bending moments
Integrated Process Planning and Scheduling of Production Systems Based on Mountain Gazelle Optimizer
Get PDFThe mass customization paradigm, in conjunction with high market demands, puts a
significant burden on contemporary production systems to output a larger quantity of
diversified parts. Consequently, production systems need to achieve even higher flexibility
levels through physical and functional reconfigurability. One way of achieving these high levels
of flexibility is by utilizing optimization of both scheduling and process planning. In this paper,
the authors propose to solve an NP-hard integrated process planning and scheduling
optimization problem with transportation constraints regarding one mobile robot. The proposed
production environment includes four types of flexibilities (process, sequence, machine, and
tool) that can be leveraged to optimize the entire manufacturing schedule. Three metaheuristic
optimization algorithms are compared on the nine-problem benchmark based on the makespan
metric. The proposed Mountain Gazelle Optimizer (MGO) is compared to the whale
optimization algorithm and particle swarm optimization algorithm. The experimental results
show that MGO achieves most best results, while it is highly comparable on the average best
results
Green Transition in Mining and AI Methodological Support in Environmental Restoration
No full textThe transition to green energy and sustainable operations poses a key
challenge for the mining industry, which has traditionally been known for its negative
environmental impact. This manuscript researchs the concept of the "green transition"
in mining, focusing on the application of artificial intelligence (AI) in methodological
support for environmental restoration. The aim is to identify and analyze technological
and methodological innovations that can facilitate the shift of mining operations towards
more environmentally sustainable practices. The current challenges in the mining
industry are analyzed, including carbon dioxide emissions, water pollution, and land
degradation. Successful green transition projects in mining are presented, highlighting
how the use of renewable energy sources and material recycling can reduce the
environmental footprint of mining activities. The role of artificial intelligence in
supporting these efforts is important. AI technologies, including machine learning and
data analytics, can significantly enhance environmental monitoring and management
processes. Specific examples of AI applications in predicting environmental risks are
presented, optimizing resource use, and developing strategies for ecosystem restoration.
AI algorithms enable more precise and efficient pollution monitoring, identification of
optimal restoration sites, and assessment of the long-term effects of mining activities on
the environment. Integration of AI into the mining industry can not only improve
environmental performance but also contribute to economic benefits through cost
reduction and increased efficiency. This paper emphasizes the need for an
interdisciplinary approach that includes collaboration between managers, engineers,
ecologists, and AI experts to achieve sustainable development goals. Further research
and investment in these areas are crucial for the successful green transition of the mining
industry and the long-term preservation of the environment. This research contributes
to the understanding of the potential of green transition in mining and the role of AI in achieving sustainable environmental solutions, providing a foundation for future studies
and practical applications
Hydrogel Ionotronics for Soft Robotic Applications
No full textAmid the frontier of emerging soft machine technology, the advancement of wearable and implantable devices via soft sensors and actuators has surged to the forefront of research interest. Hydrogel-elastomer composite materials offer a unique flexibility, biocompatibility, and responsiveness that ideal for human machine interface devices. The transformative potential of soft, flexible materials is reshaping technology across healthcare, robotics, and more. This convergence of biology, materials, and robotics leads to wearable interfaces with novel functions. Sensors and actuators, essential for human-machine interaction, require thoughtful design for optimal adaptation. Our project aims to design advanced mathematical models to simulate the behavior of such hydrogel-based composite sensors and actuators. We will merge theory, computation, and results from experiments to overcome these challenges and develop reliable predesign procedures for such fit-for-purpose devices. Within the realm of hydrogel ionotronics, our emphasis lies on hydrogel-elastomer composites with the exceptional capacity to convert mechanical stimuli into electrical signal and vice versa. We aim to develop improved electro-chemo-mechanical computational models capable of capturing complex behavior of hydrogel-based composites. A special attention will be given to the development of novel models of multicomponent and cross-diffusion in hydrogels based on fractional derivatives along with the development of efficient numerical methods to simulate intricate actuator/sensor responses
Change of speed of comfort parameters in the armored combat vehicles of the serbian army due to environmental conditions
No full textThis scientific paper refers to the conditions of the working environment of the crew members of the combat armored vehicle from the aspect of climate comfort and from the aspect of speed of the response of sensors (transducers)
Numerical and metallographic analysis of a welded joint with microcrack in the root
No full textThe goal of this research was to determine the behaviour of a welded joint with an incomplete root
penetration defect, which was subjected to tensile loads. After the actual experiments, small cracks were observed in near the fusion line, on the root side of the weld, with lengths of 0.2 and 0.3 mm, depending on the test specimen. Following the previous experience with welded joints that have multiple defects, it was concluded that further analysis is required, and for this reason, numerical models based on finite element method, which would simulate the tensile behaviour of real specimens with previously identified cracks were developed. In addition, there was the question of microstructure in this critical area of the welded joint. Metallographic tests were performed in order to determine if there was anything out of the ordinary in terms of microstructures and their distribution in the heat affected zone and the fusion line. This was decided based on previous experiments, wherein failure of tensile test specimens made of this material (which was low-alloyed low-carbon steel with commercial designation S275J2) would more often than not occur in the fusion line. Microstructural investigation, along with the numerical simulations, did not reveal anything unusual, both due to the nature of the material used and the fact that the observed cracks were too short to have a significant effect on the integrity of the welded joint. This approach, however, could prove quite valuable for materials which are more demanding in terms of welding and heat treatment
