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Search results for: data-compression
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High-density Polyethylene - Expanded Perlite Composites: Structural Oriented Analysis of Mechanical and Thermomechanical Properties
PublicationAs part of this work, research was carried out on the effect of the addition of expanded perlite (PR) on the mechanical and thermomechanical properties of high-density polyethylene (PE) composites. Composites containing from 1 to 10 wt% of the inorganic filler were produced. Polyethylene-based composites manufactured by twin-screw extrusion and formed in the compression molding process were subjected to mechanical, thermomechanical,...
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Axial capacity of steel built-up battened columns
PublicationThis paper deals with the numerical investigation aimed to study the axial capacity of pin-ended steel built-up columns. Three methods of calculating forces in chords and batten, taking into account the material and geometric imperfections specified in the Eurocode 3 are considered. The aim of this study was to compare different methods allowing the calculation of the column load capacity and determine a simpler and faster method...
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Recycling of Polyurethanes Containing Flame-Retardants and Polymer Waste Transformed into Flame-Retarded Polyurethanes
PublicationThe growing number of polyurethanes (PUs) produced every year has developed methods for their mechanical and chemical recycling which yield valuable products like substitutes for commercial polyols or flame-retardants. PUs can be produced in different shapes and forms (i.e., elastomers, flexible or rigid foams, coatings, etc.) using several different components (i.e., di- or polyisocyanates, ester- or ether-based polyols, low-molecular...
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Examination of advanced isotropic constitutive laws under complex stress states in plain and reinforced concrete specimens
PublicationThe performance of advanced isotropic constitutive laws under complex stress states in plain and reinforced concrete specimens is investigated. Three different formulations are chosen: original Mazars model, Mazars mi model and model proposed by Pereira and coworkers. The degradation of the material in all formulations is described via a single variable, but a strain/stress state is taken into account via quite sophisticated relationships....
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Simulations of hydro-fracking in rock mass at meso-scale using fully coupled DEM/CFD approach
PublicationThe paper deals with two-dimensional (2D) numerical modelling of hydro-fracking (hydraulic fracturing) in rocks at the meso-scale. A numerical model was developed to characterize the properties of fluid-driven fractures in rocks by combining the discrete element method (DEM) with computational fluid dynamics (CFD). The mechanical behaviour of the rock matrix was simulated with DEM and the behaviour of the fracturing fluid flow...
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Modelling reinforced concrete beams under mixed shear-tension failure with different continuous FE approaches
PublicationThe paper presents quasi-static numerical simulations of the behaviour of short reinforced concrete beams without shear reinforcement under mixed shear-tension failure using the FEM and four various constitutive continuum models for concrete. First, an isotropic elasto-plastic model with a Drucker-Prager criterion defined in compression and with a Rankine criterion defined in tension was used. Next, an anisotropic smeared crack...
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Influence of Fragment Size on the Time and Temperature of Ethylene Vinyl Acetate Lamination Decomposition in the Photovoltaic Module Recycling Process
PublicationPhotovoltaics is a commercially available and reliable technology with significant potential for long-term growth in nearly all global regions. Several research institutes and companies are working on recycling concepts for thin film modules and modules with crystalline cells. The establishment of recycling and reuse technologies appropriate and applicable to all photovoltaics (PV) modules is a key issue to be addressed as part...
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A novel method for drop in drop edible oils encapsulation with chitosan using a coaxial technique
PublicationThe presented work concerns a novel one step method for oil encapsulation. In this coaxial system the oil constitutes the core of the capsule, while the chitosan solution is the polymer shell surrounding the core to provide separation of the core from the external environment. The paper contains a diagram of the encapsulation equipment and explains the principle of its operation. The experimental results showed the impact of the...
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A general isogeometric finite element formulation for rotation‐free shells with in‐plane bending of embedded fibers
PublicationThis article presents a general, nonlinear isogeometric finite element formulation for rotation-free shells with embedded fibers that captures anisotropy in stretching, shearing, twisting, and bending - both in-plane and out-of-plane. These capabilities allow for the simulation of large sheets of heterogeneous and fibrous materials either with or without matrix, such as textiles, composites, and pantographic structures. The work...
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Recent Progress on Hydrogen Storage and Production Using Chemical Hydrogen Carriers
PublicationDepleting fossil fuel resources and anthropogenic climate changes are the reasons for the intensive development of new, sustainable technologies based on renewable energy sources. One of the most promising strategies is the utilization of hydrogen as an energy vector. However, the limiting issue for large-scale commercialization of hydrogen technologies is a safe, efficient, and economical method of gas storage. In industrial practice,...
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Non-standard contact conditions in generalized continua: microblock contact model for a Cosserat body
PublicationGeneralized continuum theories involve non-standard boundary conditions that are associated with the additional kinematic variables introduced in those theories, e.g., higher gradients of the displacement field or additional kinematic degrees of freedom. Accordingly, formulation of a contact problem for such a continuum necessarily requires that adequate contact conditions are formulated for the additional kinematic variables and/or...
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Numerical analyses of novel prefabricated structural wall panels in residential buildings based on laboratory tests in scale 1:1
PublicationThe paper presents experimental and numerical investigations on novel prefabricated composite building wall panels for residential building constructions. The wall panels were composed of reinforced concrete ribbed elements with the core from the EPS foam as the thermal insulation. The wall panels in the full-scale 1:1 were subjected to vertical loads. In the first step, the experiments were analysed with simple usual static methods....
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Self-compacting grout to produce two-stage concrete
PublicationTraditional concrete (TC) is primarily composed of a mixture of cement, fine and coarse aggregates, and water. TC is made by mixing together all the components before placing them. Using non-traditional concrete (two-stage concrete) to solve and to eliminate the problem of the aggregate segregation which appears in TC and in the self-compacting concrete. Two-stage concrete (TSC) consists of two main components, namely the grout...
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Influence of soil–structure interaction on seismic pounding between steel frame buildings considering the effect of infill panels
PublicationThe present research aims to study the influence of the soil-structure interaction (SSI) and existence or absence of masonry infill panels in steel frame structures on the earthquake-induced pounding-involved response of adjacent buildings. The study was further extended to compare the pounding-involved behavior versus the independent behavior of structures without collisions, focusing much on dynamic behavior of single frames....
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Experimental Study on Dynamics of Wooden House Wall Panels with Different Thermal Isolation
PublicationWood frame buildings are very popular in regions that are exposed to different dynamic excitations including earthquakes. Therefore, their seismic resistance is really important in order to prevent structural damages and human losses. The aim of the present paper is to show the results of experimental tests focused on the dynamic response of wall panels of a wooden frame building with thermal isolation made of mineral wool and...
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Experimental study on polymer mass used to repair damaged structures
PublicationA new method of repairing damaged structures by injecting the cracks with specially designed polymer mass (flexible two-component grout based on polyurethane resin) has been recently proposed. The technique is mainly dedicated to damaged masonries, especially historical structures where minimum intervention is permitted. The cracks are filled with the special injection, forming the flexible joints bonding the disrupted structural...
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Conductive Thermoplastic Polyurethane Nanocomposite Foams Derived from a Cellulose/MWCNTs Aerogel Framework: Simultaneous Enhancement of Piezoresistance, Strength, and Endurance
PublicationHigh conductivity and excellent mechanical properties of composite polymers favors their application as piezoresistive strain sensors. Nonetheless, it is difficult to develop composite polymers with desirable piezoresistance, mechanicaland durable properties. Herein, we developed conductive cellulose/MWCNTs aerogel using the freeze-drying technique. Besides, we explored the application of the highly-sensitive piezoresistive polymer...
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Investigations of size effect in concrete at aggregate level - experiments and calculations results using discrete element method
PublicationSize effect is a fundamental phenomenon in concrete. It is characterised by decreasing strength and increasing brittleness of concrete with increasing size. The thesis includes experimental and theoretical elements. The main goal of the thesis were investigations of a size effect at the aggregate level by taking fracture into account with the discrete element method (DEM) for various failure modes. Comprehensive experiments on...
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Investigation on Filaments for 3D Printing of Nasal Septum Cartilage Implant
PublicationSeptoplasty is a widely used method in treating deviated septum. Although it is successfully implemented, there are problems with excessive bleeding, septal perforation, or infections. The use of anatomically shaped implants could help overcome these problems. This paper focuses on assessing the possibility of the usage of a nasal septum cartilage implant 3D printed from various market-available filaments. Five different types...
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Effect of Particle Size of Fly Ash Microspheres (FAMs) on the Selected Properties of Concrete
PublicationThis paper presents the investigations of selected properties of concrete containing two fractions of fly ash microspheres (FAMs) with grain size up to 200 μm and up to 500 μm. Concrete mixtures with ordinary Portland cement and three substitution rates of cement by FAMs, 1.3%, 2.0%, and 2.6%, were investigated. For all concrete mixes, the constant water–binder ratio (w/b) equal to 0.50 was used. The research program included the...
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Hydrogen Storage in Geological Formations—The Potential of Salt Caverns
PublicationHydrogen-based technologies are among the most promising solutions to fulfill the ze- ro-emission scenario and ensure the energy independence of many countries. Hydrogen is considered a green energy carrier, which can be utilized in the energy, transport, and chemical sectors. However, efficient and safe large-scale hydrogen storage is still challenging. The most frequently used hydrogen storage solutions in industry, i.e., compression...
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Evaluation of the significance of the effect of the active cross-sectional area of the inlet air channel on the specific enthalpy of the exhaust gas of a diesel engine using statistics F of the Fisher-Snedecor distribution
PublicationThis paper presents the application of Fisher-Snedecor distribution F statistics to assess the significance of the influence of changes in the active cross-sectional area of the inlet air channel (Adol) flow in a diesel engine on the observed diagnostic parameter determined on the basis of measurements of the quick changing exhaust gas temperature in the outlet channel, which is the specific enthalpy of the exhaust gas stream within...
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The analysis of the influence of the corrosion protection method of selected steel elements on the steel structure life cycle costs
PublicationSteel products are widely used in the construction for the performance of essential and additional elements of engineering structures. They are characterized by high tensile strength, compression and bending, the structure homogeneity, the possibility of assembly regardless of the season and climatic conditions, ease of processing and the possibility of almost any shape. The main disadvantage of steel structures is their high susceptibility...
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Quality Evaluation of Speech Transmission via Two-way BPL-PLC Voice Communication System in an Underground Mine
PublicationIn order to design a stable and reliable voice communication system, it is essential to know how many resources are necessary for conveying quality content. These parameters may include objective quality of service (QoS) metrics, such as: available bandwidth, bit error rate (BER), delay, latency as well as subjective quality of experience (QoE) related to user expectations. QoE is expressed as clarity of speech and the ability...
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Study on some of the strength properties of soft clay stabilized with plastic waste strips
PublicationIt is well known that if plastic wastes are not well managed, it has a negative impact on the environment as well as on human health. In this study, recycling plastic waste in form of strips for stabilizing weak subgrade soil is proposed. For this purpose, a weak clay soil sample was mixed with 0.2%, 0.3%, and 0.4% of plastic strips by weight of soil, and the experimental results were compared to the control soil sample with 0%...
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The protocol for using elastic wall model in modeling blood flow within human artery
PublicationMedical diagnostic tools will play a major role in the future for an effective patient treatment and reduction their mortality, related to the cardiovascular system diseases (CVDs). There is an urgent need for developing diagnostic procedure to be robust, reliable, accurate and efficient, in the framework of a paradigm shift. Application of numerical techniques is seen as a perspective tool for such purpose. Nevertheless, existing...
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Analysis of start energy of Stirling engine type alpha
PublicationThe Stirling engine type alpha is composed of two cylinders (expansion space E and compression space C), regenerator that forms the space between the cylinders and the buffer space (under the pistons). Before the start-up and as a result of long-term operation, the average pressure in the working space (above the pistons) and in the buffer space is the same. However, in the initial phase of operation, the average pressure in the...
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Influence of the grains shape on the mechanical behavior of granular materials
PublicationDiscrete Element Method is a numerical method suitable for modeling geotechnical problems concerning granular media. In most cases simple forms of grains, like discs or spheres, are used. But these shapes are capable of soil behavior modeling up to a certain point only, they cannot reflect all of the features of the medium (large shear resistance and large volumetric change). In order to reflect the complex behavior of the real...
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Self-compacting grout to produce two-stage concrete
PublicationTraditional concrete (TC) is primarily composed...
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Mechanical Properties of Additively Manufactured Polymeric Materials—PLA and PETG—For Biomechanical Applications
PublicationThe study presented herein concerns the mechanical properties of two common polymers for potential biomedical applications, PLA and PETG, processed through fused filament fabrication (FFF)—Material Extrusion (ME). For the uniaxial tension tests carried out, two printing orientations—XY (Horizontal, H) and YZ (Vertical, V)—were considered according to the general principles for part positioning, coordinates, and orientation typically...
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Modeling the application of steel slag in stabilizing expansive soil
PublicationThe objective of this study was to evaluate the suitability of steel slag as an additive to the engineering properties of weak clay soil. Different geotechnical laboratory tests were conducted on both stabilized and natural soils. Steel slag (SS) was added at a rate of 0, 5, 10, 15, 20, and 25% to the soil. Specific gravity, grain size analysis, Atterberg limit test, compaction test, free swell, California bearing ratio (CBR),...
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Compact High Efficiency and Zero-Emission Gas-Fired Power Plant with Oxy-Combustion and Carbon Capture
PublicationReduction of greenhouse gases emissions is a key challenge for the power generation industry, requiring the implementation of new designs and methods of electricity generation. This article presents a design solution for a novel thermodynamic cycle with two new devices—namely, a wet combustion chamber and a spray-ejector condenser. In the proposed cycle, high temperature occurs in the combustion chamber because of fuel combustion...
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Drill holes decrease cancellous bone strength: A comparative study of 33 paired osteoporotic human and 9 paired artificial bone samples
PublicationThis study was designed to compare compressive strength of cancellous bone retrieved from the femoral head in a specimen with and without guide wire hole, with comparison to synthetic bone samples. Femoral heads retrieved from 33 patients who sustained femoral neck fractures and underwent hip arthroplasty were cut into cuboids leaving two matching samples from the same femoral head. Similar samples were prepared from synthetic femurs....
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Synthesis, characterization, and interactions of single-walled carbon nanotubes modified with doxorubicin with Langmuir–Blodgett biomimetic membranes
PublicationThe synthesis, characterization, and the influence of single-walled carbon nanotubes (SWCNTs) modified with an anticancer drug doxorubicin (DOx) on the properties of model biological membrane as well as the comparison of the two modes of modification has been presented. The drug was covalently attached to the nanotubes either preferentially on the sides or at the ends of the nanotubes by the formation of hydrazone bond. The efficiency...
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Laboratory station for research of the innovative dry method of exhaust gas desulfurization for an engine powered with residual fuel
PublicationContemporary methods of exhaust gas desulfurization in marine engines are all expensive methods (4-5 million euro). This is, among other reasons, due to the limited market audience, but primarily due to the monop-olized position of manufacturers offering fabrication and assembly of this type of marine ship installations. Proposed as part of a research project financed by the Regional Fund for Environmental Protection and Maritime...
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Anisotropy and compaction gradient assessment on rammed earth specimens through sonic tomography approach
PublicationRammed earth is a traditional construction technique that has recently gained attention because of its benefits from an ecological perspective. The conservation of the existing valuable cultural heritage sites and the quality control of new constructions built with this material require the development and application of practical inspection techniques. This paper explores the application of sonic tests and sonic tomography as...
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Mathematical approach to design 3D scaffolds for the 3D printable bone implant
PublicationThis work demonstrates that an artificial scaffold structure can be designed to exhibit mechanical properties close to the ones of real bone tissue, thus highly reducing the stress-shielding phenomenon. In this study the scan of lumbar vertebra fragment was reproduced to create a numerical 3D model (this model was called the reference bone sample). New nine 3D scaffold samples were designed and their numerical models were created....
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Tuning of microstructure in engineered poly (trimethylene terephthalate) based blends with nano inclusion as multifunctional additive
PublicationImmiscible blends and their composites are heterogeneous and have variable morphology due to variation in mesophase regions. Tuning, i.e. controlling the phase dimension is important, thereof we report a “super-combo” effect of multiwalled carbon nanotubes (MWCNTs) in poly (trimethylene terephthalate)/polypropylene (PTT/ PP) blend system. MWCNTs act as a good reinforcing agent and compatibilizer in the otherwise immiscible PTT/...
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Development of a spray-ejector condenser for the use in a negative CO2 emission gas power plant
PublicationOne promising solution for developing low-emission power technologies is using gaseous fuel combustion in pure oxygen when the exhaust gas mixture is composed of H2O and CO2, and where CO2 is separated after steam condensation. The paper presents the results of computational analyses providing to the Spray-Ejector Condenser (SEC) development, which is one of the crucial components of the negative CO2 gas power plant (nCO2PP) cycle...
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DEFORMATIONS OF INNOVATIVE COLD-FORMED GEB SECTIONS
PublicationPermanent urban growth of the world of today world implies demanding challenges for the steel construction industry. Nowadays, one of the most important issues is the cost optimization of steel structures. Since the weight of building materials is a major component of the total cost, engineers and designers try to reduce structural weight, without compromising durability and sustainability of a steel structure. Therefore, light...
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Some aspects of the constitutive modelling of natural fine grained soils
PublicationThe monograph deals with selected problems of the constitutive modelling of natural fine grained soils commonly known as clays. The main idea is not to propose a unified model which is capable of describing all known features of mechanical behaviour of fine grained soils. Instead, separate models are proposed describing the mechanical behaviour of heavily overconsolidated, lightly overconsolidated and normally consolidated clays....
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L1 Cell Adhesion Molecule Overexpression Down Regulates Phosphacan and Up Regulates Structural Plasticity-Related Genes Rostral and Caudal to the Complete Spinal Cord Transection
PublicationL1 cell adhesion molecule (L1CAM) supports spinal cord cellular milieu after contusion and compression lesions, contributing to neuroprotection, promoting axonal outgrowth, and reducing outgrowth-inhibitory molecules in lesion proximity. We extended investigations into L1CAM molecular targets and explored long-distance effects of L1CAM rostral and caudal to complete spinal cord transection (SCT) in...
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A study of a compact high-efficiency zero-emission power plant with oxy-fuel combustion
PublicationThis paper discusses the application of global trends in gas cycles technology using oxy-fuel combustion. This is followed by a demonstration of a design solution for a new cycle with two enhanced energy-converting devices, namely a wet combustion chamber and a spray-ejector condenser. The proposed gas and steam cycle unit is contained within a single turbine, whose benefits combine those offered by gas turbines (high inlet temperatures)...
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Molecular transformation of dissolved organic matter in manganese ore-mediated constructed wetlands for fresh leachate treatment
PublicationThe organic matter (OM) and nitrogen in Fresh leachate (FL) from waste compression sites pose environmental and health risks. Even though the constructed wetland (CW) can efficiently remove these pollutants, the molecular-level transformations of dissolved OM (DOM) in FL remain uncertain. This study reports the molecular dynamics of DOM and nitrogen removal during FL treatment in CWs. Two lab-scale vertical-flow CW systems were...
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Petrophysical analyses of rock construction materials from the Roman rural settlement in Podšilo bay on Rab island (NE Adriatic, Croatia)
PublicationThis article presents the results of petrophysical analyses of limestones and sandstones used for the construction of the wall structures of a Roman rural settlement located in Podšilo Bay on Rab Island (Croatia). An on-site analysis of the walls indicated the use of different lithotypes, which is an uncommon case in the area. So far, no petrophysical properties of the applied materials have been tested, and their provenance...
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Improving Thermal Insulation Properties for Prefabricated Wall Components Made of Lightweight Aggregate Concrete with Open Structure
PublicationPorous concrete is commonly used in civil engineering due to its good thermal insulation properties in comparison with normal concrete and high compression strength in comparison with other building materials. An extremely porous concrete, called ‘lightweight aggregate concrete with open structure’ (LAC), is used in some German plants to produce prefabricated wall components. They are used mainly in hall buildings, e.g. supermarkets....
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The cement-bone bond is weaker than cement-cement bond in cement-in-cement revision arthroplasty. A comparative biomechanical study
PublicationThis study compares the strength of the native bone-cement bond and the old-new cement bond under cyclic loading, using third generation cementing technique, rasping and contamination of the surface of the old cement with biological tissue. The possible advantages of additional drilling of the cement surface is also taken into account. Femoral heads from 21 patients who underwent a total hip arthroplasty performed for hip arthritis...