bluuebunny/crossref_metadata_2025_split huggingface dataset:
The efficiency of electric power supply with the transmission of peak loads to distributed generation
Authors: Yu Brostilova T , Ageev V A , Golobokov S V , Sotnikov M V 
Published: October 2021

Abstract
A model of a radial power supply system in MatLAB was compiled to perform the research. The transformer substation is represented by a step-down transformer, the load of the substations in the form of a resistance. Electricity is transmitted to the substations along three power transmission lines. The power center is represented by an ideal source. A reserve source of limited power is connected to the remote substation. We made calculations of the voltage drop in the lines, voltage at the inputs of substations and electricity losses for transit. The study of the radial power supply system was performed in the daytime maximum mode; the minimum load mode was performed at night and in the peak load mode. As a result of modeling the operating modes, the indicators of the classical radial power supply scheme were compared with the indicators of the system when the local generation facilities were switched on during the working shift or during peak hours. Connection of reserve sources allows reducing voltage fluctuations along the line and reducing power losses for transit.
Numerical simulation of processes in the latent-heat thermal energy storage tank
Authors: Faizullin R O , Zakharova V Y , Baranenko A V 
Published: October 2021

Abstract
This paper has proposed a computer model for numerical calculations of heat flows in regular rhombic packed bed of capsules with phase change material. The mathematical model of heat transfer in a capsule is based on finding a zero-dimensional solution to the Stefan problem, considering the influence of convective flows arising in the liquid phase. To take into account the heat transfer due to the convective component in the liquid phase in the capsule, the effective thermal conductivity coefficient is calculated. An experimental dependence has been applied to describe the heat exchange conditions of the coolant and the capsule wall. The calculation is reduced to finding the temperature of the coolant t after passing one layer of packed bed. The resulting temperature is the input parameter for calculating the next layer. This operation is repeated until the calculation is made for all layers of packed bed. The numerical calculation has been performed in the mathematical software Scilab. According to the proposed model, the results of calculating the temperature of the coolant after passing the storage device correlate well with the experimental data for a thermal energy storage device with spherical capsules filled with paraffin.
Thermophysical analysis of heat-insulated glued laminated profiled timber for wooden houses
Authors: Tsvetkov N A , Kozlobrodov A N , Boldyryev S , Romanenko S V , Nemova T N , Tsvetkov D N 
Published: October 2021

Abstract
The paper presents the thermophysical analysis of two types of the wall system made of heat-insulated glued laminated timbers with connectors comprised of water-resisting multilayer plywood. The paper describes a novel timber configuration, which reduces the weight of one square meter area by 55% compared with an ordinary timber having a cross-section of 0.21 m × 0.21 m and saves not less than 60% of wood. The latter is highly relevant because forests remove carbon dioxide emissions from the atmosphere; reducing the use of wood in construction is of great importance for ecology. The ANSYS finite element program is used for calculating temperature fields and heat fluxes. It is found that one connector affects not more than 0.2 m of the exterior wall length in relation to the temperature and heat flux fields, whereas the heat loss increase is not over 0.44%.
Use of chelators and hydrofluoric acid for the improvement of well productivity
Authors: Khai Le Viet , Veliev M M , Sh Mukhametshin V , Veliev E M , Tyncherov K T , Andreev A V 
Published: October 2021

Abstract
The paper presents the results of microscopic analysis of the content of elements on the surface of clay samples after treatment with an acidic mixture of HV:HF. The analysis showed that as a result of the dissolution of clay and quartz, quartz dissolves faster, the Si/Al ratio on the sample surface decreased, which indicated the formation of a protective film of aluminum phosphate silicate. The studies of the ability of chemical reagents to dissolve clay by the method of weight loss showed that in the HV:HF system, the dissolution rate of clays is much lower due to the formation of a coating layer. The stage of the increase in the rate of dissolution occurs when a part of this layer is dissolved. The studies of the ability of the HV:HF chemical reagent system to dissolve silicon showed that the amount of dissolved silicon varied linearly with the exposure time and the rate of silicon dissolution was proportional to the HF concentration in the system. The dissolution rate of silicon in the HV:HF system is much higher than in the HCl:HF system at the same HF concentration. This is a significant advantage of the proposed system of chemical reagents HV: HF in comparison with the traditional HCl:HF system. HV: HF system dissolves calcium carbonate much more efficiently than traditional hydrochloric or acetic acid systems.
Aspects regarding the behaviour and comfort of reusable wool protective masks in the context of the COVID 19 pandemic
Authors: Dochia M , Kaminszky R , Fogorasi M S , Bucevschi A , Barbu I , Popa A , Nicolaescu C 
Published: October 2021

Abstract
In the current context of involvement in the fight against COVID 19 wearing protective masks are strictly necessary to limit the spread of the virus SARS-CoV2. Since the appearance of this virus, solutions have been sought to cover the needs of masks for the population and also to improve their wearing comfort compared to nonwoven fabric (TNT) masks. These masks are made of chemical fibres and it is recommended to be worn for a maximum of 4-8 hours and then they must be discarded. In this study, two types of masks from wool and silk blended knitted fabrics were manufactured and analysed. The masks were initially subjected to manual ironing sterilization and disinfection. Subsequently, several analyses were performed: specific mass, density, abrasion and pilling resistance, colourfastness to crocking, colour fastness to accelerated laundering, air permeability, bacterial filtration efficiency and breathability. The analysed masks can be washed and disinfected at home and are reusable. This aspect offers a strong sense of safety for the user, but also has beneficial effects on environmental protection. Even so, they do not correspond to bacterial filtration efficiency. Eventually, the comfort perception of about 300 volunteers was also taken into consideration.
Study of the functional parameters of main engine turbocharger for a tanker ship
Authors: Faităr C , Jugănaru D , Buzbuchi N , Stan L-C , Poenaru V 
Published: October 2021

Abstract
To correctly understand the requirements of a system, we must first study its schematics. In the case of energy systems, they require a detailed diagram of energy performance. Heat losses can be classified into high-temperature losses, medium-temperature and low-temperature losses. On board ships with low-speed propulsion engines, heat recovery systems operate in the range of 100-400 °C. Many residual energy recovery systems from internal combustion engines are under development: for example the MAN WHR development program for Tier III technologies. In this paper, I will treat both theoretical calculation elements and real elements of the operation of the turbocharging system, for the main reference engine. I chose to treat this system because it is a main subassembly for the engine, in terms of operation and thus its efficiency. In the theoretical calculation, I will start from the initial calculation data and I will expose the geometric and functional parameters of the turbocharger. The exhaust gases up to a temperature of 650 °C passes continuously through the turbine and heat its components, without its system of contraction cooling. In particular, the shaft bearing must withstand high operating temperatures without ever breaking the lubrication device. On the compressor side, the air is heated to over 200 °C. High temperatures lead to extreme thermal loads of the material in many locations. Speeds are extremely high: METxxSE turbochargers, as in figure 1, run at speeds between 10000 and 35000 rpm, depending on size. In this respect, the tangential speeds of 560 m / s and even more are reached at the compressor turbine, which rises to 1.7 times the speed of sound or 2000 km / h. The efficiency of the operation of the turbocharger system related to the main propulsion engine depends on the internal processes that take place in its operation, and also on the environmental conditions. In this way, the direction of processing on the installation is dictated by the engine load, taking into account the extreme situations, corresponding to the operation of the ship in special conditions (overload, tropical temperature, arctic temperature etc.).
Analysis of precipitates in heat treated thermo-mechanically processed steel with a high yield strength
Authors: Górka J , Poloczek T , Kotarska A , Jamrozik W 
Published: October 2021

Abstract
The aim of this study was to analyse the precipitates and determine their impact on the structure of thermomechanically processed high strength S700MC steel. The tested samples were subjected to a heating process at temperatures from 100°C up to 1300°C with a 100°C step. The chemical composition analysis in the micro-areas of the samples, thin-film tests and quantitative measurements of carbonitride precipitates were performed. In order to describe the grain size, a method of calculating the number of grains cut through the measuring line was used. In order to determine the effect of heat treatment on strength and plastic properties, Charpy V-notch, Vickers hardness and static tensile tests were carried out. The study showed that S700MC steel is characterized by a non-equivalent, fine-grained bainitic-ferritic structure. The test showed a significant impact of heat treatment on the strength and plastic properties of S700MC steel.
High-pressure water jet cutting of S235JR steel alloy. Influence of process parameters on dimensional accuracy
Authors: Grigoraș CC , Chiriță B , Brabie G , Zichil V , Herghelegiu E , Tâmpu C , Ciubotariu VA 
Published: October 2021

Abstract
This paper aims to determine the influence that water jet cutting parameters have on dimensional accuracy. The input parameters of this study were the workpiece material, that was made from 19 mm thick S235JR steel alloy plate, using a medium to high cutting pressure (2000, 2500, and 3000 bar), with a variable standoff distance (1, 2, and 3 mm) and a programmed quality of the cut from Q1 to Q5. A statistical interpretation of the results was conducted, and the experimental plan was obtained using the Response Surface Method. The samples were analysed for entrance and exit width of cut and kerf angle. A total number of 45 samples were measured, and the results were interpreted using an ANOVA analysis for statistical significance (p-value) and fit statistics (R2). The results have shown what values are optimum for the input parameters to obtain precision cutting quickly.
Finite element modelling of a plan polymeric composite product under impact and thermal conditions
Authors: Ion S M , Nitoi D , Chivu O , Opran C G 
Published: October 2021

Abstract
Polymeric composites products are undeniable trends today, especially in the most innovative fields and with a permanent degree of novelty. The specialized literature presents a very wide range of their applications in the avant-garde fields such as the aerospace field and that of the automotive industry. Paper presents the results of research on modelling and impact simulation of these types of products besides a transient temperature analyse using the finite element method. Starting from the experimental part through which a flat composite product is made, the authors research its behaviour on impact and at the same time try to make a mathematical model by the finite element method. This comes to complete the experimental research by providing information on the mechanical stress that occur during experimental testing. The properties of the materials both those used in the realization of the experimental product and in the simulation are those offered by the manufacturers. The input data used in the finite element simulation tries to provide an image as close as possible to the probable behaviour of the product in case of car crash. Considering obtained results, large-scale industrial application is envisaged for automotive polymeric composite parts leading to the increase of the safety of the traffic participants in optimal vehicle manufacturing conditions.
Design of production systems using computer modelling of human-robot interaction
Authors: Kampa A , Gołda G , Konysz D 
Published: October 2021

Abstract
Designing a production system is a complex process that requires many factors to be taken into account, including the interaction between a human and a machine. The industrial robot is a specific type of a handling machine, which can work similarly to a human, and can be used in different areas in a factory. Therefore, there is a need to consider all important human and robotic factors early in the manufacturing process and industrial system design. Especially the computer simulation of the production processes with the use of Discrete Event Simulation method, carried out for the needs of a new project, allows us to already include the process flow at the industry system planning stage, before real implementation. The purpose of this work is developing a framework of a digital twin of a manufacturing system. An example of a newly designed manufacturing system for the production of elements from the automotive industry is presented, as well as simulation models developed in the FlexSim program, which enables predefined parametrized objects for humans and robots. An area requiring improvement was defined, and the possible effects of these actions on the overall process were reengineered, considering the parameters of availability, performance, quality, and failure rate that make up the OFE (Overall Factory Effectiveness) metric. The information obtained during the simulation allowed us to define the location of the bottleneck in the process, and thus determine what to focus on during the implementation of the manufacturing line. In the future, the models will be expanded in perspective of using the digital twin in Industry 4.0.
An Analysis of the Thermal Simulation of Parts Processed by Cutting, with Different Geometries
Authors: Olaru I , Olaru C 
Published: October 2021

Abstract
In practice, different cutting processes are encountered, each process having different characteristics. Due to the existing friction forces between the workpiece and the cutting tool, a significant amount of heat is generated. This amount of heat can be determined by experimental measurements. With the help of the SolidWorks program, the geometric element that must be studied can be made, so that later it can be studied from the point of view of the thermal behaviors following the processing. We will take into account the different critical areas that may occur and that may materialize through areas where the final surface is not compliant. This paper aims to study the way in which the temperature is propagated in the workpiece, so that the phenomenon can be understood and determined how this excessive heat can be removed from the cutting area.
Structural strength evaluation of a 3000 dwt river-barge, under oblique quasi-static design waves
Authors: Perijoc D S , Domnisoru L , Angheluta C M 
Published: October 2021

Abstract
The present study consists of the 3D-FEM global structural analysis of a typical open-top, double-hull, 3000 DWT inland navigation barge, having 90 m in length. The 3D-FEM model developed to perform the evaluation idealizes the barge structure with high accuracy, average element size being in the range of 50-75 mm. Two loading cases were analyzed, consisting of the ballast and full loading conditions. For the equilibrium floating condition in calm water and oblique design waves, an eigen iterative scheme has been used to generate the input parameters for the 3D-FEM analyzed cases. The push-barge finite element model has been subjected to oblique quasi-static design waves, headings ranging from 0 to 75 degrees. Wave heights considered in the analysis range from 0 to 1.2 m, step 0.3 m, corresponding to the Danube navigation conditions and freeboard limit imposed by the classification societies for inland navigation vessels. Numerical results following the FE analysis have been assessed by the yielding stress ratio, von Mises criterion, and the maximum deformation, thus indicating the structural areas that need to be improved in the design process.
Optimisation of the production process in manufacturing a smart equipment for precision agriculture
Authors: Roşu M M , Cotfas P A , Iliescu M 
Published: October 2021

Abstract
The paper presents the optimizing process of a production system that it is intended for manufacturing process of a customized smart equipment. The initial variant (already in use) of this equipment dose no longer fit the requirements for precision agriculture so, new concept and, further, prototype development are to be done. The objective is to have smart innovative equipment suitable for digging furrows with controllable depth and geometric shape, not to mention its ability to determine soil’s moisture. The depth and geometric shape of the trench section are important elements in preparing the soil for irrigation as they ensure controlled slope for water runoff. Humidity is important for establishing and controlling the irrigation norm. Once the new equipment prototype is manufactured, tested and validated, it will be produced in series. For this it is necessary planning, programming and optimization of the production process so that to obtain a competitive product on the market through quality and price. Also, the transition from single production to series production involves great adaptability of the production process using self-optimization, self-configuration and self-diagnosis procedures, which are able to support and assist the human operator in the complex process of handling workpieces in the process.
Noninvasive evaluation of elastic properties for magnesium-calcium biodegradable alloys
Authors: Savin A , Steigmann R , Craus M L , Stanciu M D , Istrate B , Munteanu C 
Published: October 2021

Abstract
Bone injuries can be fixed and stabilized using degradable implants from magnesium - calcium alloys. Mg and Ca being natural elements in human body, they are easiest to be absorbed without causing toxicity problems. The aim of the paper is to present the effect of Gd and Mn addition in 0.5wt.% in order to improve elastic properties of Mg-Ca0.5-[E]x (E = Mn or Gd) and possibility to be used as biodegradable materials. The addition of Mn / Gd in the binary MgCa alloy modify the structural properties of the alloy (analyzed as elastic properties, respectively crystallographic structure). The measurements and the results calculus were carried out using the ultrasound methods and the Resonant Ultrasound Spectroscopy.
Influence of the ball screw stiffness on the positioning accuracy of the CNC machine tools
Authors: Stoica A , Stan G 
Published: October 2021

Abstract
This work is researching the ball screw stiffness influence on the positioning accuracy of the feed kinematic linkage of a CNC machine tool fitted with an indirect type measuring system for positioning the moving element. Because the machine tool is equipped with an indirect measuring system, backlashes and elastic deformations in the kinematic linkage cannot be offset by the position loop, consequently these are directly affecting the positioning accuracy. In this context, methods are used for diminishing their influence as well as compensation methods with a view to improve the positioning accuracy. Ways to preloading the ball screws and bearings of the ball screw are presented as well, by focussing on the optimisation, through calculations, of the preloading force value. An important component, analysed in this work, consists of the research of the ball screw–nut stiffness that depends on the strategy being used on the axial bearing of the two ends of the ball screw. The experimental tests have been performed at idle running on the CNC milling machine (CPFH 500), fitted with three controlled axes (X, Y and Z). Based on the experimental results, it may be noticed that, once increased the ball screw stiffness, within the limits stated by the ball screw supplier, the positioning accuracy will increase as well.
Thermal influence on the positioning accuracy of the CNC machine tool rotary tables
Authors: Tanase I , Stan G 
Published: October 2021

Abstract
This work analyses the perturbing thermal sources and design solutions to avoiding the thermal effects. The analysis is focused, as main factors of the thermal dilatation, on the rotary tables, the guiding systems, the radial one and, especially, the axial one (that takes over the weight of both table and work piece), as well as on the positioning of the driving servomotor that is a thermal source in the vicinity of the rotary table. The new solutions presented in this work refer to the rotary tables with direct measuring whose number of indexing positions is 360000 that means a minimum increment of 0.0001degrees. It is to be mentioned that this structure allows the kinematic linkage of the rotary table to take part to machining. If the rotary table provides positioning only, the table will have a clamping system that confers a high stiffness, needed for heavy duty cutting. The experimental trials have been carried out on a machining centre of the Micro-production workshop of the University in Bacau. The size of the rotary table is 630x630 mm. Repeated trials have been performed for determining the positioning accuracy through the modification of the thermal conditions of the worm-wormed gear mechanism. The results have proven an enhancement of the positioning accuracy of approximately 7%.
Laser welding of 4330V steel with a micro-additive of vanadium
Authors: Żuk M , Stano S 
Published: October 2021

AbstractThis article presents the results of a test of laser welding of high-strength low-alloy steel with a micro-additive of vanadium. Steel 4330V is a delivery material after heat treatment. Welded joint was made by laser welding using a TruDisk 12002 disc laser. As a result of welding, a joint was formed which was subjected to visual and penetration tests from the face side, as well as macro and microscopic tests. Impact tests were carried out at reduced temperature in the weld and in the heat affected zone (HAZ). The resulting joint was also subjected to the Vickers hardness test, bend test and the tensile strength test. This research show how the low-alloy high-strength material behaves during welding without processing before and after welding. In results after welding show incomplete penetration from the root side. No cracks on the weld face. In HAZ hardness was of 520HV0.5and tensile strength of joint was on level1077MPa.