bluuebunny/crossref_metadata_2025 huggingface dataset:
Composition of Engineering Drawing through Communication Skills and Social/Material Interactions from the Semiotic Aspect
Authors: Lille H , Ruus A
Published: December 2019

The report analyses how to better proceed from general discussion on graphic literacy in engineering education, through communication between the triad components: concept (problem, engineering idea, existing object), teacher and student, from the semiotic point of view, using Peirce’s triadic model whose the basic claim is that signs consist of three inter-related parts: object, interpretant and represent. A pedagogical model is presented in the form of a triad, where problem solving is focused on form: object-problem identification or existing product; interpretant-teacher and interpretant-student who form teacher concept (TC) and teacher representation (TR), and student concept (SC) and student representation, i.e. engineering drawing (SD). At all stages of the learning process the teacher must rely on interpreting students’ representations as the evidence of their understanding. Successful application of representational images (engineering drawings) is not a simple task; it is something that must be trained and used in professional practice, as manufacturing of real products is based on engineering drawings.
A review study on specific requirements for refurbishment of military buildings in cold climates
Authors: Prozuemnts A , Borodinecs A , Krizmane M
Published: December 2019

In most cases there are no specific and clear design requirements defined in local building codes, the responsibility for appropriate design of military buildings therefore lies primarily on third party design service contractors that are hired upon a short term agreement, whereas government is primarily involved in financing stages and military personnel is solely involved in long term exploitation of these structures. Authors of this paper focus on analyzing and isolating specific requirements for refurbishment of military buildings with regards to their structural reliability, safety, endurance, fire and explosion-resistance, heating, ventilation and air-condition systems performance and efficiency, as well as adding energy efficiency, building performance optimization recommendations and measures in moderate and cold climate conditions.
Energy performance of temporary shelters
Authors: Borodinecs A , Geikins A , Smirnov S
Published: December 2019

This paper analyzes methods for calculating energy consumption of temporary shelters for the purpose of reducing energy consumption for heating and improving the level of comfort. Mobile shelters are widely used by rescue emergency teams. Often such type of buildings has a limited access to reliable source of energy supply. Thus it is vitally important to make correct heat losses analysis to select proper capacity of energy source. The paper presents analysis of heat losses of rubber/fabric shelters without extra thermal insulation.
Energy saving potential of ventilation systems with exhaust air heat recovery
Authors: Zemitis J , Borodinecs A
Published: December 2019

The paper presents the results of data gathering regarding the heat recovery efficiencies of different heat recovery types at various air flows supplied by some of the most common manufacturers. The study showed that the average heat recovery efficiency of modern, commonly used rotary heat exchangers is around 83% while for counter-flow exchangers around 86%. Also, in the paper, the simulation results of heat energy consumption and recovered heat potential for the single-family house are presented. The simulations are performed in IDA-ICE software and show that for the specific building it is possible to reduce the heating energy up to 84% if ventilation with heat recovery is used. The results also showed that in case the internal heat loads decrease, then it slightly affects the heat recovery potential. In the case of no internal gains, this value decreases by 4%.
Development of the experimental stand for investigation of the drying process in moist walls
Authors: Cieślikiewicz Ł , Łapka P , Mirowski R , Wasik M , Kubiś M , Pietrak K , Furmański P , Seredyński M , Wiśniewski T
Published: December 2019

The paper presents development of the experimental stand for investigation of drying process in a part of a wall which consisted of about twenty bricks joined by mortar. The thermo-injection method was applied for drying. In the first stage of this method several holes are drilled in the moist wall and are used to mount heating probes. These probes supply air to holes and at the same time heat air and the wall up. Then hot air leaves the hole flowing along its boundaries and heating and drying the wall. In the second stage holes are used for impregnation of the wall with hydrophobic fluid which creates waterproof membrane. The stand was based on a precise platform balance applied to measure the variation of global moisture content in the specimen. Moreover, local variations of moisture content were measured applying TDR method. The temperature measurements were carried out using RTDs which were placed in different locations in the wall. Additionally, the IR thermography was applied to register temperature on the specimen surface. The stand was closed in an insulation chamber to decrease the impact of the surroundings. The paper contains the preliminary results of measurements which test operation of the stand.
New numerical model of heat and moisture transfer in the wet brick
Authors: Seredyński M , Furmański P , Łapka P , Wasik M , Cieślikiewicz Ł , Pietrak K , Kubiś M , Wiśniewski T , Jaworski M
Published: December 2019

The subject of this study is numerical modelling of the fully coupled heat and moisture transfer in the building material, i.e., in a brick. The new mathematical model of equilibrium transport of heat and moisture in the form of continuous liquid medium (funicular region), discontinuous liquid medium (pendular region) and gaseous phase with dry air is proposed. As independent variables, the total mass moisture content and temperature are chosen. Both energy and moisture balance equations are mutually coupled. It is due to dependence of capillary and vapor pressures on the moisture content and temperature. Additionally, vaporization and condensation phenomena are also accounted for in the energy balance equation. Both transport equations are supplemented with boundary conditions expressing the coupled heat and moisture transfer at the dried wall or heat transfer at impermeable walls. Balance equations are discretized on the rectangular control volume grid in the framework of the in-house computational code. A grid-based method of generation of the control volume mesh is proposed, with ‘half’ control volumes related to boundary grid nodes created at domain walls. This approach enables deeper insight into implemented code as well as simplifies analysis of influence of selected terms in balance equations and implementation of complex hygro-thermal boundary conditions.
Numerical models for long-term performance assessment of lightweight insulating assemblies
Authors: Birjukovs M , Apine I , Jakovics A
Published: December 2019

This paper presents the results of numerical modelling of hygrothermal processes in test buildings situated in the Botanical garden of the University of Latvia. Long-term performance of wall, floor and ceiling insulating assemblies for five different buildings was simulated using WUFI Pro 6.3. On the experimental side, measurements of temperature and relative humidity at key points of assembles have been accumulated over a period of roughly six years and material samples were taken from building envelope materials for biological analysis. We found that our models rather successfully reproduce the experientially observed temperature and relative humidity dynamics. In the process, we established material models for building envelope components, as well as different parameters that we previously unknown. We also compared mould growth risk predictions via the Sedlbauer critical curve model derived from both simulations and experiment against the results of lab tests conducted on materials samples - all three were found to be in good agreement, indicating that the Sedlbauer model is applicable to local climate conditions, as well as further validating numerical models.
Calculation of initial and long-term heating costs for a nearly zero energy single-family building over 30 years
Authors: Gendelis S , Miķelsons M , Jakovičs A
Published: December 2019

In practice, during the design stage of a building, only the initial costs are taken into account. These costs are also discussed with the customer and optimised with the aim of reducing them. It is the global costs over a longer period that show the real difference in the total expenses of living in a particular house, however. In this study, one newly built, nearly zero energy single-family building was studied in detail using a comparative global cost calculation methodology. The most popular insulation materials, construction types, types of windows, and types of floor construction in Latvia are included in the calculation of the costs. The results demonstrate that initially cheaper building means lower global costs during the analysed 30-year operating period due to initial costs are significantly higher than all other costs including energy costs, meaning that changes in construction type and building materials affect the initial cost more than the long-term energy costs. In parallel, different modern heating systems (including heat pumps) were included in the analysis to calculate and compare heating expenses. The results show that almost all the heating systems have the same energy costs regardless of fuel type for the 30-year period, however, the initial costs of these systems vary due to the different used technologies. Therefore, only the sum of the initial and long-term energy costs provides objective information about heating systems that are optimal in the long-term.
Considerations on transients in a water supply distribution network
Authors: Constantin A , Nițescu C S
Published: December 2019

Lipnița is a village situated in a hilly region, in Constanta County. The water supply system has its own groundwater water source, placed in the middle of the village at a low elevation. Water is conveyed, by a long transmission duct to a storage tank from which it flows by gravity to the consumers. The distribution network has two long mains that intersect in a manifold with isolation valves, situated in the middle of the village. This topology of the system shows high static head for the transmission duct and high elevation differences between the end consumers and those in the centre of the village.

The paper presents an analysis, by numerical simulation, on the transients that occur in two different segments of the system.

The simulation was performed either for the original old steel made network, aiming at identifying the vulnerable cross sections and extreme pressure values. The results showed that maximal pressure values are not dangerous, but cavitation occurs along the pipeline. The same simulation was carried out for the new PEHD pipelines. The change of material and the increase in diameter of the new pipes showed better results regarding pressure variation during transients. Cavitation is avoided.
Velocity modification at the bridge abutments because scour
Authors: Gjunsburgs B , Vilnitis M , Parilkova J , Bizane M
Published: December 2019

At the corner of the abutment were streamline concentration, sharp water level drop and rapid increase of velocity. Formula for calculation local velocity at the abutments is elaborated. Local velocity is depending on open flow parameters, backwater value, rate of contraction by bridge crossings and depth of scour. Relative local flow modification at the bridge abutment at plain river bed, relative local and critical velocities changes during scour at steady and unsteady flow, uniform bed and at bed layering is studied. Comparison of the local velocity with approach flow and mean velocity under the bridge opening was made. The local velocity Vlt
is reducing and the critical velocity V0t is increasing because of the scour within the time step at steady or at unsteady flow. When relative local velocity βV0t/Vlt
becomes equal to one the scour stops. For unsteady flow local and critical velocities are different at any steps of hydrograph because of the increased flow discharge and the scour depth. Dependence of the relative local and critical velocities at steady and unsteady flow, development in time and because of the scour, impact layering of the river bed is presented in paper in Figures and compared with tests results.
Lightweight concrete with expanded aggregate from siliceous rocks
Authors: Zakrevskaya L V , Gandelsman I A , Gavrilenko A A , Lubin P A
Published: December 2019

The purpose of this study is to develop technology for the production of a new building composite made of silicon-containing rocks. An aggregate is foamed granules obtained on the basis of diatomite with the addition of caustic soda, dolomite, water and liquid glass. The material composition, materials processing, physical and mechanical properties have been observed. The problem of alkali-silicate interaction typical for traditional Portland cement and glass phase is solved through the use of magnesia binder. Samples on Portland cement and magnesia binder were obtained, the aggregate content was varied. Some aggregate fractions were used to obtain high packing density in the composite. Concrete was estimated according to density, compressive strength and tensile strength, water absorption and thermal conductivity. Analysis of the material structure was made. The results of the study of the microstructure of synthesized concrete indicate the presence of a cement matrix in which granules of various sizes are tightly packed. The results of X-ray phase analysis of synthesized concrete indicates that the cement matrix consists of forsterite crystals. Approximate savings in the use of concrete with the developed aggregate is about 10-20%. Such savings are possible due to the fact the surface occurrence of siliceous rocks allows them to be mined in an open way with minimal costs compared to other rocks, with a lower calcination temperature during material creation.
Drying Shrinkage Deformation Comparison Between Foam Concrete, Geopolymer Concrete, Disintegrated, and Non-disintegrated Cement Mortar
Authors: Gailitis R , Sprince A , Pakrastins L , Sahmenko G , Kozlovskis T
Published: December 2019

Foamed concrete has been known as a building material for nearly 100 years. In the beginning, it was used as an insulation material with very low density. Since then there have been attempts to make this material more load-bearing and structural. In present-day foamed concrete is being used in soil reinforcement, building blocks and in other sorts of building applications [1]. Another innovative material - the geopolymer concrete has been around only for 40 years. It is being used in buildings and infrastructures objects such as railroads, reservoirs, and houses and others. The main benefit of the geopolymer is that it is green material that is partially made by utilizing waste products. The geopolymer manufacturing carbon footprint is 2 times less than the Portland cement carbon footprint. Another way to reduce Portland cement carbon footprint is to reuse old cement. In the past few decades, there has been a considerable amount of researches regarding the partial replacement of cement using disintegrated cement in cement mortar or concrete. As it is known to obtain powder mineral filler material planetary ball milling is applied, but it is ineffective. It has been discovered that grinding by collision is a more effective method for refining brittle material. One of the ways to refine is to disintegrate with disintegrator. This raises the question of whether old cement disintegration together with sand can improve its long-term properties and what differences do these different cement and alkaline activated compounds have. The aim of this article is to determine the difference of shrinkage deformation for foamed concrete and disintegrated cement mortar which is Portland cement based cement composites and geopolymer concrete which represents alkali-activated cement composites. The size of all shrinkage specimens was 46mm in the diameter and 190mm in height. The shrinkage deformations of the specimen were determined by consistently measuring specimen deformation displacement. Shrinkage deformation values for foamed concrete in the 81st day did reach 11.85mm *10−2, disintegrated old cement mortar 4.88mm *10−2, non-disintegrated new cement mortar 5.02mm *10−2, non-disintegrated old cement mortar 4.33mm *10−2, but for geopolymer concrete, on the 81st day, it was 3.73mm *10−2.
Effect of sodium lignosulfonate superplasticizer on the early hydration of cement with different contents of cubic C3A
Authors: Mezhov A , Kovler K
Published: December 2019

In this research, the influence of the sodium lignosulfonate superplasticizer (LS) on the early hydration of two types of cements containing different amount of cubic C3A was studied. It is shown that at 0.1% addition of LS has no significant influence on the hydration, while at higher dosages LS contributes to the additional formation of ettringite. This phenomenon is observed for both types of cement. The higher ettringite formation was found for the cement containing higher C3A amount. However, LS addition retards the hydration, which is indicated by the reduction of the portlandite amount formed.
Sustainable construction success indicators
Authors: Vilnītis M , Lapsa V A , Veinbergs A
Published: December 2019

The proposed paper examines the success indicators of sustainable construction projects, and its relationship to building codes with specific focus on safety, quality and budget aspects in terms of their implications and impacts prior, during and after construction. Such a research will be very beneficial to the construction industry and the government of all countries in terms of significant money savings and preservation of national wealth and resources through sustainable construction approaches. Consideration of sustainability at the design stage is emphasized. Building safety and the roles of building codes in prevention of structural failures are also covered in the paper together with factors affecting building failures and methods for their prevention in early design phases. Construction process is introduced in the paper from the perspective of modern total quality management. Concepts of quality management, quality control, quality assurance and six sigma and how they relate to building sustainability are discussed with examples. At least the importance of appropriate maintenance of building during expected life time are partly covered in the paper. It was necessary, in an initial stage, to define the key indicators that should be considered in order to assess the main aspects of sustainable construction. This paper intends to present the analysis that was performed in order to select some of quality evaluation indicators.
Life cycle assessment for masonry exterior wall assemblies made of traditional building materials
Authors: Zimele Z , Sinka M , Bajare D , Jakovics A
Published: December 2019

Building materials contribute a significant amount of CO2 to overall greenhouse gas emissions and this environmental impact should be reduced to improve the sustainability of the construction industry. Although new and low-carbon materials are emerging, the majority of materials used are still traditionally produced and are highly carbon intensive, such as masonry blocks and insulation slabs – rock wool or expanded polystyrene. To assess which of the traditionally used building materials are more sustainable, in this paper, wall models of the most widely used masonry blocks and insulation materials were analysed using life cycle assessment. The wall models were created to fulfil the requirements of nearly-zero energy buildings. The assessment showed that the lowest impact on the environment is from aerated concrete blocks and expanded polystyrene insulation, which is mostly due to low weight and raw materials consumption compared to other materials. On the other hand, expanded polystyrene insulation poses more danger to humans and the environment in its use phase than other materials due to emissions during fire and degradation, thus should be used with caution.
Identification and Monitoring of Degraded Real Estate in the Context of Urban Environmental Analysis and Development Planning in the City of Riga
Authors: Amoliņa I , Zīra M , Geipe I
Published: December 2019

Nowadays real estate plays an important role in the life of a person: it is one of the important elements of the quality of life (dwelling, workplace), as well as of public spaces, especially the outdoor space, i.e., the elements that make up the image of the city and the aesthetic enjoyment of the city. The topical issue under consideration is directly related to the physically deteriorated real estate that falls into the category of degraded or even dangerous buildings and structures. The article aims at investigating the problems of identifying, assessing and monitoring the degraded real estate in the context of urban development. The topicality of degraded objects is also observed in the main national and municipal development planning documents. The quality of real estate is assessed by different institutions according to the specificity and necessity of their activity, for example, planning and monitoring of territory development, application of real estate tax, as well as determination of the value of real estate. However, according to the research conducted within the article, information on real estate is not always up to date, available or linked between different holders of information sources. Different institutions evaluate the same thing at different levels of detail, but there is currently no fast, efficient and accurate exchange of information. This can be explained by disorganised administrative and legal issues, as well as the inefficiency of mutual communication.
Asphalt Recycling Technologies: A Review on Limitations and Benefits
Authors: Rathore M , Zaumanis M , Haritonovs V
Published: December 2019

Recycling of asphalt pavements gained popularity in 1970s due to the rapidly increasing cost and reducing supply of oil and hence - bitumen. However, presently there are other reasons to develop this technology, the main being the ability to utilize non-renewable resources. Sustainability of asphalt pavement construction can only be ensured if we are able to utilize the available reclaimed asphalt pavement (RAP) material completely in the new construction. Another potential advantage is the mutual benefit of using RAP in conjunction with warm mix asphalt (WMA). This is due to compensation of hardened binder from RAP with softer binder of WMA. For such mixes, significant energy savings can be realized due to the lower mixing and compaction temperature as well as due to lesser efforts required for compaction. This paper summarises several approaches that can be adopted to maximize the amount of RAP material in asphalt mixtures. In addition, the current recycling practices implemented in the industry are discussed to identify the main reason behind the lacking confidence in using high RAP content in mixes. The environmental and economical benefits of high rate of recycling are also discussed. Finally, the possible research directions that will allow to incorporate high proportion of RAP without compromising the performance of pavement are discussed.
Effect of wetting/drying on the properties of OSB/3 and birch plywood
Authors: Kask R , Lille H , Kiviste M , Tamm R , Lääne J O
Published: December 2019

In this study the thickness swelling (TS), restore dimensions (RD), density (D) and modulus of rupture (MOR), after ten cycles of wetting over/drying, of commercial boards, i.e. 3-layered OSB/3 (“SWISS KRONO“, thickness 12mm) and 9-layered birch (betula sp) plywood with phenol-formaldehyde (UPM-Kymmene, Otepää, Estonia), were investigated according to EN standards. Test samples (dimensions of 290×50×12 mm3) for determination of a change in the investigated parameters, according to the standard EVS EN 326-1:2002, were cut from the boards in the parallel (ǁ - major axis) direction to the face (outer layer) strand. The cutting forehead and the facet edges of the test samples were coated with the water repellent masticKiilto Fibergum(“KIILTO OY“). The specimens were altered by soaking in a tank with water (22±1°C) for 24 hours and dried for 48 hours in a ventilated drying box at 65 ± 1°C. Before testing, the samples were conditioned in a climatic chamber at a relative humidity of 65% at 21°C. The surfaces and cross-sections of the initial dry samples after the first wetting/oven-drying cycles were studied using the X-ray technique. The analytical exponent- and linear-fractional equations were used to approximate the obtained experimental data depending on the number of cycles.
Damping Identification and Prediction for Laminated Composite Plates
Authors: Wesolowski M , Barkanov E
Published: December 2019

Laminate composite structures are widely used in different sectors of industry due to their remarkable stiffness and damping performance. The present study focuses on the damping identification and prediction for laminated composite plates. The damping model based on the strain energy method was used for damping coefficients identification and for modal loss factor prediction. The study concerns with the damping coefficients identification for a single layer of an unidirectionally laminated plate. The reliability of the proposed identification method is validated by numerical modal loss factor prediction for a plate made of the layers in question but having different geometric characteristics. Further, the predictions of the modal loss factors were also validated by a vibration test. All the vibration tests necessary for the current study were performed in a non contact manner using laser vibrometer. The results delivered from the identification method were proven to be credible for modal loss factor prediction.
Lamina properties non-destructive characterisation of asymmetric carbon fiber reinforced laminates
Authors: Namsone E , Ermakov D
Published: December 2019

A non-destructive technique – numerical-experimental method, based on vibration tests is applied for the characterization of lamina properties of asymmetric carbon fiber reinforced laminates. The main idea of this procedure is the determination of simple mathematical models (response surfaces), using the finite element analysis at the reference points of experimental design. Therefore, a significant reduction of computational efforts can be attained. For the purpose of characterization, two asymmetric carbon fiber laminated specimens were prepared, using the prepreg manual layout technology. To evaluate the elastic material properties obtained, the numerical resonant frequency, determinated by using identified material properties, were successfully compared with experimentally measured and high accuracy with average relative error less than 1% was reached.
Numerical Comparison of HPFRC and HPC Ribbed Slabs
Authors: Buka-Vaivade K , Sliseris J , Serdjuks D , Sahmenko G , Pakrastins L
Published: December 2019

The problem of limited resources is actual nowadays. One of the ways for solving this problem can be the use of high-performance fiber reinforced concrete as a structural material for elements subjected to the flexure. The dispersive reinforcement improves the properties of the concrete and allows reducing the required dimensions of cross-section and ratio of longitudinal reinforcement for members subjected to flexure. This research includes the numerical comparison of ultimate limit state and serviceability limit state of ribbed slabs from high-performance concrete (HPC) and high-performance fiber reinforced concrete (HPFRC) behavior, considering the different deformative properties of these materials. The effective use of these materials has been studied using a nonlinear finite element model. This model is created by using a beam type element with a multilayer cross-section, where each layer has a non-linear stress-strain relationship, according to the layer materials such as HPC, HPFRC, or steel bars. The finite element model used for the limited plates is validated. Results of experiment showed, that used calculation model describes with sufficient accuracy the behaviour of the ribbed slabs. The difference between design and experimentally determined breaking load is less than 6% for ribbed slab. The use of HPFRC for ribbed slabs with the spans from 6 to 12 m is justified so as using of HPFRC instead of HPC enables to increase 42-46% the intensity uniformly distributed load for the ribbed slabs with the same cross-sections and allowed deflections.
Self-healing concrete with crystalline admixture – a review
Authors: Guzlena S , Sakale G
Published: December 2019

Concrete is the most used construction material for years. However long term serviceability is an issue, when we focus on sustainable building and use of materials. In long term service different types of visual and structural defects can appear in concrete structures. Defects in material enhances due to aggressive factors in outdoor (chlorides, sulphides and carbonates, freeze-thaw) which reduces material properties over a longer period. Mainly defects on visible surfaces of structures are from mechanical impacts, environmental exposure or due to impropriate maintenance. There are methods to reduce the risks and improve service life. One of them is self-healing materials, like bacteria, crystalline additives, in-capsulated healing agents and other. Use of self-healing material has preference, like lower maintenance costs for inspection, monitoring and complicated repair. Crystalline admixtures have several advantages comparing to other self-healing techniques, like improved concrete water tightness, no need for encapsulation before addition to concrete mix, which reduces sample preparation time.
Shear Failure of Sandwich Panels Subjected in Bending
Authors: Daugevičius M , Skuturna T , Valivonis J , Patapavičius A
Published: December 2019

The paper describes the behaviour of the sandwich panels in bending. Two panels of the same dimensions are tested. The panels differ only in the layout of the inner thermal insulation layer. The thermal insulation layer is made of separate mineral wool slabs. The graphs of the strain development in the external sheets, the displacement between the layers and mid-span displacement are presented in the paper. The nature of the failure shows that only separate internal thermal insulation slabs resist the shear force. Therefore, the complete width resistance cannot be evaluated. The views of the failure are also presented.
Parametric identification of multy-storey building model based on oscillation testing results
Authors: Volkova V , Gaile L , Pakrastins L
Published: December 2019

Buildings and structures are complex systems having predetermined parameters, which should be controlled in the process of manufacturing structures, construction and installation. In some cases, oscillations are the most dangerous effects on the buildings and structures. Significant alternate stresses caused by oscillational actions leads to accumulation of damage in the material. It causes the appearance of fatigue cracks and destruction. In addition to fatigue failure in mechanical systems there are other phenomena that cause changes in the structure of the surface layers of the parts to be joined and consequently the reduction of the frictional force in the joint. The object of the study is a multi-storey building having a rectangular shape in plane. Structural scheme of the building is a two spans frame. The frame of the building consists of monolithic reinforced concrete structures. According to the analysis of the basic diagnostic parameters of the technical condition of buildings and structures, affect their stability and reliability are geometrical parameters of buildings and structures, and their main structural elements, as well as physical and mechanical parameters of structural elements of building and dynamic parameters of buildings and structures. An analysis of methods for determining the dynamic parameters of buildings has shown that the main criteria for assessing the technical condition of bearing structures, using the dynamic method, is the period and frequency building oscillation. Dynamic tests were conducted to determine the dynamic and rigid characteristics of bearing structural elements of the building and structures, detection of hidden defects. According to the method of measuring the dynamic parameters, the degree of damage to a building or structure, is determined by the comparison of the design values of dynamic parameters, periods of eigenoscillations, and the decrement of oscillations with experimentally obtained data.
Numerical Modelling of High Strength Fibre-Concrete’s columns in Multi-Storey Building
Authors: Sliseris J , Buka-Vaivade K
Published: December 2019

The complexity of architecture is continuously growing. Therefore, it is necessary to develop a new construction system with complicated topology using less human work. A fibre-concrete is very promising material to solve those problems. However, design methods of fibre-concrete load bearing structures such as columns are not well developed. Therefore, a new numerical simulation framework is proposed for analysis of fibre-concrete structures macro scale. The method can take into account non-linear post-cracking behaviour of fibre concrete. This includes local fibre orientation in thin elements, anisotropic continuum damage models on different scales, efficient meso-scale fibre orientation prediction tools and others. The proposed method is used to analyse building’s columns where part of structural elements is made from fibre-concrete. The effectiveness of fibre-concrete is estimated and proposed a guideline for optimal design using fibre-concrete.
Characterization of crack formation and development in the oil&gas well casing cement sheath
Authors: Paegle I , Marcos-Meson V , Fischer G
Published: December 2019

The oil industry relies on the use of cement as a primary barrier, to isolate the steel casing from the surrounding formations and provide overall stability on the bored structure. There has been extensive technological development on the physical and mechanical properties of the materials from the cement and cementing industry, in order to produce and install effective cement barriers, capable of withstanding both physical and chemical loads under extreme wellbore conditions. In particular, the formation of cracks and interfacial damage at the primary cement sheath is a largely discussed issue. However, there is still a limited understanding about the crack formation and propagation processes in well-cements, due to the particular geometric and boundary conditions of the structural system, such as: pressure, temperature, and confinement conditions. This paper is focused on the crack formation and propagation processes on cement systems under wellbore-like geometrical conditions, and proposes a test-setup to evaluate cracking and localized damage at the casing-cement interface.
Use of Artificial Neural Network for Initial design of steel structures
Authors: Mote H , Satish Kumar S R
Published: December 2019

Design of steel structures is an iterative process that often turns complicated when requires initial guess. A good initial design guess that comes from past design experience can considerably reduce the number of subsequent analysis and design cycles. It is difficult to form declarative rules to express human intuitions and past experience. Another problem in design process is arriving at optimal solution, where optimization process in most cases is computationally expensive and time consuming. Artificial Neural Network (ANN) is a promising computational model that can perform cognitive tasks, such as learning and optimization. This paper focuses on application of ANN in design so as to make design process more efficient. The aim is to train ANN to arrive at optimal solution by considering design constraints along with practical. This is illustrated with an example of design of compression member which primarily requires initial guess. The economy in design is tried to obtain by providing training set of optimal solutions to a multilayer neural network. The design process followed to generate training set is in accordance with IS: 800-2007. The solutions given by ANN are approximate but have reasonable agreement with the expected solutions.
Development of a high clay content earth plaster
Authors: Lagouin M , Laborel-Préneron A , Magniont C , Aubert J-E
Published: December 2019

Earth, as a building material, offers many advantages: on an ecological point of view, it is a natural, abundant, recyclable material with low energy used for production and transportation. Moreover, earth is known to be a natural humidity regulator and to improve comfort inside buildings, making it a good choice for indoor plastering. The clayey phase gives the global cohesion of the material by acting as a binder for the sand grain skeleton. The finest grain soil fraction is responsible for the dry strength, the water vapour permeability and the sorption capacity of earthen plasters. However, clay also induces the drying shrinkage of the mortar leading to the cracking of the plaster. The objective of this work is to improve the moisture buffer capacity of earthen plaster by increasing its clay content without jeopardizing the general behaviour of plasters. Based on consistency, shrinkage and shear tests, the characteristics of mortars in fresh and hardened states were evaluated. The hygric regulator potential of earthen materials were measured through the Moisture Buffer Value (MBV) test. As expected, results have shown that, to maintain a standard level of consistency, an increase in the clay content leads to a greater amount of mixing water. Moreover, to enhance the MBV, the highest possible earth content must be used. Addition of organic admixtures can be considered to improve the high-clay content plaster behaviour without jeopardizing the aesthetic and mechanical aspects of plaster.
Experimental assessment of bio-based earth bricks durability
Authors: Laborel-Préneron A , Giroudon M , Aubert J E , Magniont C , Faria P
Published: December 2019

Construction is one of the most polluting industrial sectors, that is the reason why developing sustainable building materials is a world-wide interest. Earth bricks have recently been more and more studied, mainly regarding their mechanical and hygrothermal properties. The interest in adding plant aggregates to an earth matrix, notably to improve the thermal behaviour, has also been shown. However, durability of the materials is a major concern to sustain performance levels, to limit maintenance and to ensure the comfort and safety of the occupants. Although earth construction seems to be durable, with the various examples of the vernacular heritage in France and all over the world, unstabilised earth is quite sensitive to environmental factors (weather, occupants, micro-organisms). The resistance of an earthen material to liquid water is particularly low, and the addition of plant fibres may decrease its resistance even more. Moreover, the incorporation of organic matter, containing cellulose, raises questions about the composite resistance to moulds. Investigations are thus needed to assess several durability properties. The present paper studies and compares durability of earth bricks containing 0% and 3% weight content of barley straw, lavender straw and rice husk. Some durability tests corresponding to weathering or occupants’ actions are conducted: a wet erosion test is performed to simulate rain or accidental water droplets and the resistances to dry abrasion and to impact are also appraised. The resistance to fungal growth is also investigated. Results show a considerable interest in adding lavender straw in earth bricks. Indeed, a very good compromise has been found concerning properties of weathering durability and to microorganisms. The addition of lavender straw improves the dry abrasion resistance of earth bricks whereas rice husk and barley straw additions decrease it. The two types of straw greatly increase the resistance to wet erosion of earth bricks while rice husk only in a smaller extent. Concerning the brick resistance to impact, its behaviour is considerably improved by the addition of the three kinds of plant aggregates, particularly rice husk. Finally, as expected, the bricks made of earth alone are the more resistant to fungal growth. However, the addition of rice husk maintains a very high resistance with the first mould observed after only 10 weeks of incubation at 93% of relative humidity and 30°C.
Calorimetric Investigation of Two Factors Influencing the Maximum Storage Capacity of Calcium Chloride Hexahydrate
Authors: Schmit H , Rudaleviciene D , Rathgeber C , Hiebler S
Published: December 2019

CaCl2·6H2O is a salt hydrate that is attractive as phase change material (PCM). However, in literature, different values are indicated for its melting enthalpy. Here, two possible influence factors on the maximum storage capacity of CaCl2·6H2O are investigated via differential scanning calorimetry (DSC): deviations of the water content from the stoichiometrically correct concentration and different basic raw materials used in the preparation process. While both influence factors are found to have a considerable impact on the maximum storage capacity of CaCl2·6H2O, the influence of deviations of the water content is more important than that of the basic raw materials.
Control of geometrical parameters of a single layer at additive forming of products by FDM technology
Authors: Grechukhin A N , Kuts V V , Oleshitsky A V
Published: December 2019

Questions are considered about the accuracy of the formation of the surface layer by additive methods. The analysis of works is carried out on a research subject. High values of the error of forming (approximation) are revealed at forming of surfaces of a complex profile by additive methods. The spatial orientation of a single layer is proposed to reduce the error of forming products by additive methods . Mathematical dependences are proposed to determine the value of the parameters of a single directed layer on the results of experimental studies.
Information-measuring system to improve the quality of motion control robot manipulators
Authors: Goryanina K I , Katin O I , Vernezi M A , Donskoy D Yu , Tregubenko L A , Chiem N X
Published: December 2019

The use of robotic systems consisting of mechanical manipulators and control systems is now widely used not only in industrial production, but also in medicine, sorting and even in everyday life and services. In recent years, the market of service robotics has been actively developing. Successful implementation of automation systems depends on solving complex scientific and technical problems primarily in the following areas: machine vision, sensor networks, navigation systems. Of particular importance is the task of increasing the accuracy of manipulation. The article proposes a variant of the formation of information-measuring system of the robot manipulator based on MEMS sensors. And also recommendations on the choice of sensors of the sensor system to control the manipulation system of the robot are given.
Analysis of the possibility of levitation of ferromagnetic bodies in a static magnetic field
Authors: Vernezi M A , Goryanina K I , Katin O I , Donskoy D Yu , Lukyanov A D , Tooraj A N
Published: December 2019

The hypothesis of the existence of three-dimensional regions near the sources of the magnetic field, in which it is possible to obtain a stable position of the magnetic object in a stationary field. The hypothesis is based on the existence of two types of points: points with zero field level and points with local extremum of this field. The obtained distributions of magnetic forces act stabilizing on the object under study, in particular, create the effect of levitation of ferromagnetic bodies in the gravitational field of the Earth. Examples of configurations of the field sources that generate many such points. Systems of current windings providing creation of one-and two-dimensional configurations of areas near sources within which magnetic levitation is possible are analyzed.
The study of the use of multi-disc safety friction clutches in the working bodies of crank presses
Authors: Kobzev K O , Bozhko E S , Mozgovoi A V , Kostromina E I , Babenko L G
Published: December 2019

Studies of safety couplings have shown that when the friction forces in splined joints of friction disks and half couplings are taken into account, the moment of friction of the clutch increases compared to the moment calculated without taking these forces into account. Among the safety clutches, friction clutches occupy a special place in use in crank presses due to the increased accuracy of limiting the transmitted load. This allows you to increase the efficiency of protection of parts and drive units of machines, as well as reduce their weight and dimensions.

Friction disks are pressed against each other with the force created by the spring, and the moment of friction arising between them ensures the connection of the leading parts with the followers. The friction force in the slots significantly reduces the transmitted force of pressing on subsequent disks, but its influence is not taken into account in existing studies.
Objectives of increase of capacity and lifetime of municipal solid waste dump according to density index study
Authors: Larin D , Staseva E , Khetsuriani E
Published: December 2019

The problem of the optimal waste management of industrial and household waste is extremely important due to large amount of accumulated and annually produced waste. One of the crucial aims to improve ecological quality and environmental safety and compliance is to improve efficiency of waste management. The vast majority of solid domestic waste landfills are used up, but design, construction and place new territories into operation for receiving and waste disposal will take 3-5 years. In this work, issues of definition of the residual capacity of landfill are considered, aiming to expand the capacity and usage period, based on the solid landfill body density index research. Study object is solid household waste landfills in Rostov region, study subject is anthropogenic filling layers of the landfill. In order to support business objectives, there was conducted engineering and geological research, wells were drilled, laboratory studies were undertaken and soil tests were analyzed. Experimental results show the possibility to continue waste disposal works in the current landfill by means of increase of waste density index and free geometric scope.
Reconstruction of electromechanical device for blocking dust emissions
Authors: Minkin M S , Kuimov D N
Published: December 2019

As a result of the work, a new configuration of the electrode system was investigated based on the application of the particle behavior prediction method. The new configuration of the electrode system allows for a lower supply voltage to increase the bulk density of the electric field charge in the interelectrode space, to increase the time of the dust particle in the interelectrode space, and also reduces the risk of electrical discharges on the corona electrodes. Calculation on the developed special software product was made for different geometry of the interelectrode window (120,150,200 microns). Computer simulation of physical processes in the interelectrode space, analysis of the dynamics of the charge set by the dust particle, as well as calculation of the forces acting on the dust particle confirmed the efficiency of the chosen geometry of the electrode system.