bluuebunny/crossref_metadata_2025_split huggingface dataset:
Influence of CFRP Strengthening on the Behavior of Concavely-Curved Soffit Concrete Bridge Girders
Authors: Al-Ghrery K , Kalfat R , Oukaili N , Al-Mosawe A , Al-Mahaidi R 
Published: January 2020

Abstract
Over the last few decades, fiber reinforced polymer (FRP) has been increasingly used in strengthening different structural concrete members. The main objective of this research is to study the influence of curvature on the performance of curved soffit reinforced concrete (RC) bridge girders that have been strengthened with carbon fiber reinforced polymers (CFRP). This experimental program was designed to evaluate the effect of concavity and soffit curvature on the CFRP laminate utilization and load capacity, compared to flat soffit RC beams strengthened with the same CFRP system. Accordingly, five beams, 2.7 m in length and having the same degree of soffit curvature (20 mm per 1 meter) extending over 2 meters of the span length, were tested under three-point monotonic static loading up to failure. CFRP pre-cured laminates were used for external strengthening in flexure. It was observed that 20 mm/m degree of curvature reduced the load-carrying capacity of strengthened concavely curved RC beams by 15.9 – 17.8%.
Effect of Compaction Methods on the Morphology of Aggregates in Hot Mix Asphalt
Authors: Abed Mohammed A. , Abed Alaa H. 
Published: January 2020

Abstract
Hot mix asphalt plays a very important function in determining a pavement’s capacity with regard to major failures, such as fatigue, permanent deformation, and thermal-associated cracking. Hot mix asphalt’s behaviour is affected by the mechanistic attributes and shape of its constituent aggregates, alongside the geometric properties of those aggregates such as position and orientation. This paper focused on characterising the aggregates used in producing hot mix asphalt and their allocation within such asphalt mixes using digital image processing (DIP) methods. Additional laboratory tests were also performed in order to match compaction methods used in the laboratory with those occurring in the field. The results provided evidence that this methodology offers simpler and faster ways to provide a full indication of the behaviour of aggregates during compaction and to determine their tendency to randomise throughout the compaction process. ImageJ Fiji software was found to be competent to characterise aggregates’ constituent forms and orientations; randomness, represented by vector magnitude, is determined in an aggregate directional array as an orientation factor (Δ) and used as a reference for better interlocking where heavy compaction is used. This factor ranges from 0 to 100%, where 0% indicates completely random particles and 100% indicates that particles are exactly within a single array. Mixes compacted with a Superpave gyratory compactor (SGC) and roller compactor had aggregate particles with relatively higher numbers of contact points and randomness than those mixes compacted using a Marshall Hammer. The results also showed that vector magnitude is an approach to determining field compaction, with results of 82.6, 67.43, and 90.7% for SGC, Marshall Hammer, and roller compacter compaction, respectively. This makes it clear that SGC and roller compaction are the nearest types of compaction to those used the field. DIP also showed that the percentage of contact points in various types of compaction were 63.6 and 92.9% for Marshall and roller compacters, respectively, while field core was found to have 88.4% contact points when produced by SGC.
Experimental Hybrid Testing of a Concrete Filled Steel Tube (CFST) Bridge Pier Subjected to Vertical and Horizontal Ground Motions
Authors: Ali Al-Attraqchi , Javad Hashemi , Riadh Al-Mahaidi 
Published: January 2020

Abstract
Hybrid simulation is a form of advanced testing that combines both numerical and experimental techniques to achieve an economical seismic response assessment of structures. The technique utilises the best feature of computer simulations and combines these with experimental testing. This makes hybrid simulation a powerful platform for experimentally studying the seismic responses of structures to collapse. This paper presents an application of hybrid simulation for tracing the seismic responses of a concrete filled steel tube (CFST) column subjected to combined horizontal and vertical ground accelerations. A state-of-the-art testing facility, known as the multi axis substructure testing (MAST) system, was used to impose complex boundary effects on the physical specimen using mixed load and deformation modes. The column was subjected to five increasing ground motion levels. During the test, the column experienced large axial force variations of up to 2.2 MN and reached a maximum drift of 8.8% without significant damage. The results demonstrate that this CFST column is thus capable of resisting large compression and tension forces, offering high levels of ductility without collapse.
A Heat Recovery Method of Internal Combustion Engine Using a Thermoelectric Generator
Authors: Imran Murtdha S. , Hashim Hasan.T. 
Published: January 2020

Abstract
The means by which engines lose energy include losses such as friction between the moving parts and heat. The heat losses are larger than the friction losses, and the largest portion of heat loss occurs in the exhaust system. The recovery of heat losses represents a power gain by the process and reduction in engine fuel consumption. An experimental study was conducted for utilizing waste exhaust heat to generate electricity using thermoelectric generators. The test engine was a four-stroke, single-cylinder, air-cooled spark ignition (SI) engine. Four thermoelectric generators were installed at the upper surface of the engine silencer, with two aluminium heat sinks in order to decrease the cold side temperature. The experimental results showed that the generated voltage from the four thermoelectric generators went up with increase in the hot side temperature, and time. The maximum voltage generated was 11 volts under natural convection effect. The study was accomplished at engine speed 2200rpm with brake power 1473.77 W and fuel consumption of 0.83kg/hr.
Investigation of Environmentally-Friendly Alternative Refrigerants for Automotive Air Conditioning Systems
Authors: Abbood Mohammed Hasan , Hashim Hasan T , Amin Amin S 
Published: January 2020

Abstract
The popularity of automotive transport and the length of time people now spend in their cars mean that most vehicles come equipped with an automobile air conditioning (AAC) system. Most of these use refrigerant fluids, which affect the environment and increase global warming. Therefore, many territories have laws that mandate the use of environmentally-friendly refrigerants with zero ozone depletion potential (ODP) and low global warming potential (GWP). The ACCs in most existing motor vehicles use R134a as a refrigerant, which has a high GWP. The aim of this study is to investigate alternatives to R134a that are characterized by environmentally-friendly qualities such as low GWP, are available and can be charged directly into an existing system without modification. Therefore, thermodynamic analysis of an AAC system containing R134a was conducted and the results compared with blends formed by mixing hydrocarbons (HCs) (R290/R600a), which are flammable, environmentally-friendly and ultra-low GWP refrigerants, with R134a (R600a/R290/134a). The mixing of HCs and R134a led to reduced flammability and used R134a in a ratio within low GWP criteria, to decrease the cost and the amount of its banked. Refprop software was used for the thermodynamic analysis. Theoretical results revealed that the blend of (R600a/R290/134a) with a mass ratio (43/35/22) has low GWP, provides the same level of refrigerant performance and can be used directly without any modification to the system.
Influence of Refill Friction Stir Spot Welding Technique on the Mechanical Properties and Microstructure of Aluminum AA5052 and AA6061-T3
Authors: Mahdi Akeel Z. , Amin Samir A. , Bakhy Sadeq H. 
Published: January 2020

Abstract
This paper presents the effects of using the refill friction stir spot welding (RFSSW) technique on the mechanical properties and microstructure of aluminum AA5052 and AA6061-T3. Specimens were first prepared from AA5052 sheet of thickness 2 mm and AA6061-T3 of 1.6 mm, for chemical analysis and mechanical tests. Workpieces were then stir spot welded by RFSSW at four rotational speeds (2000, 2500, 3000 and 4000 rpm) using two tool pin diameters (5 and 7 mm) to carry out the tensile shear tests. Microhardness testing was conducted at the best conditions along the cross-section of the welded specimens, as well as microstructure examination. The results of the tensile shear tests manifested that, for AA5052 and AA6061-T3 at the tool rotational speeds 2000 rpm and 3000 rpm, respectively, using a tool pin of 7 mm the ultimate tensile shear force was slightly higher than at other speeds in both diameters of tool pin (5 and 7 mm). However, the microhardness results displayed a W-shape at the best conditions. Finally, the microstructure inspection revealed the morphology of the major zones of the weld joint.
Effect of SiC Particles on Microstructure and Wear Behavior of AA6061-T6 Aluminum Alloy Surface Composite Fabricated by Friction Stir Processing
Authors: Abbass Muna Khethier , Baheer Noor Alhuda 
Published: January 2020

AbstractThis research studies the effect of SiC particles on the microstructure and wear behavior of AA6061-T6 aluminum alloy surface composite. Friction stir processing (FSP) was used to incorporate micro-sized SiC particles into AA6061-T6 aluminum alloy to form a particulate composite surface layer. Samples were subjected to two passes of FSP with and without SiC powder at the best rotational speed of 1250 rpm, travel speed of 32 mm/min and two passes in the same direction. Microstructural observations were conducted via optical and scanning electron microscopy (SEM) of samples subject to FSP. Mechanical properties, including microhardness and wear resistance, were evaluated. The results manifested that at two passes, the FSP caused a more uniformity in the distribution of SiC particles. The addition of SiC particles to AA6061-T6 improved the hardness (improvement 62.6%) and wear resistance as compared to FSPed sample without SiC particles. The wear behavior was of a mild type or an oxidative type at low loads (5 N), which became severe or metallic wear at higher loads (20 N) for sliding time 20 min.
Improvement of Mechanical Properties of Magnesium (Mg) Matrix Composites Reinforced with Nano Alumina (Al2O3) Particles
Authors: Abed Zaid Hayder Muneam , Abed Abdul Rahman N. , Hasan Hala Salman 
Published: January 2020

Abstract
Nano alumina particle-reinforced magnesium was fabricated by powder metallurgy technique. Powders were mixed by ball milling (without balls) for 6 hours at rotation speed 60 rpm. Then, the powder was compacted at 550 MPa and sintered at 530°C for 2 hours. The magnesium contained 0.25, 0.5, 1, 1.5, 3, and 5 vol. % nano alumina Al2O3. The physical, mechanical properties and microstructures, such as density, porosity, compressive strength, hardness, wear rate, SEM and EDX, were measured and compared with the values of unmodified pure magnesium samples. The results revealed an improvement with Al2O3 in Mg matrix composites. The greatest improvement in UCS and Hv values were about 197 MPa and 70 Hv at the volume fraction of 3 vol.% Al2O3 respectively. The wear tests showed that wear resistance was increased with the increasing of the reinforcement volume fraction of Al2O3.
Study of bending resistance of sandwich structures
Authors: Šuba O , Kubišová M , Šuba O , Měřínská D , Pitnerová L 
Published: January 2020

Abstract
Article deals with the study of the flexural limit state of sandwich structures based on fiberglass and polymeric foams. Whether geometrical and material parameters influence the resulting load-bearing capacity of these structures are studied experimentally using FEM models. This study shows it is necessary to particular emphasis attention to the issue of flexural strength, the load capacity when of the walls designing sandwich shell products to avoid possible failures in the practical use of these types of structures. Subsequently, Horn’s evaluation method is used to compare the experimental testing and the FEM model.
The Influence of the Three-Layer Mouthguard on the Stress-Strain State of a Pair of Opposing Teeth
Authors: Avdeeva E S , Kamenskikh A A 
Published: January 2020

Abstract
The aim of the study was to consider the contact interaction of a pair of opposing teeth with and without taking into account the three-layer mouthguard. The strain-stress analysis of the biomechanical model was undertaken within the framework of the elastoplastic stress-strain theory. 7 geometric configurations of the mouthguard were considered within a wide range of functional loads which were varied from 50 to 500 N. We obtained the distribution of the stress and strain intensities in a pair of opposing teeth during contact interaction at a different level of physiological load. The dependences of the maximum level of stress intensity and the intensity of plastic deformations in the biomechanical model were established. Contact parameters were considered near the zone of dental occlusion.
Influence of a Delamination Defect Location on the Operating Life of a Multi-Layered Composite Sample
Authors: Anoshkin A N , Pisarev P V , Ermakov D A 
Published: January 2020

AbstractIn the framework of this research, the authors proposed an algorithm for predicting the residual life of structures made of polymer composite materials (PCM) using the structural-phenomenological model. To assess the residual life of PCM structures under cyclic loading, it was proposed to use the approach of explicit description of the adhesive layers destruction process. In accordance with the developed algorithm, in the process of cyclic loading in the adhesive layers, the level of damage was recorded; upon reaching a critical damage level, the adhesive layers destruction was simulated. The algorithm was tested on sample structures with a defect in the form of delamination and without defects. A numerical study of the delamination defect location influence at the onset of fatigue failure of model structures was carried out.
Nanostructuring of a Surface Layer as a Way to Improve the Mechanical Properties of Hypoeutectic Silumin
Authors: Kondratyuk A A , Ivanov Yu F , Klopotov A A , Ustinov A M , Abzaev Yu A , Petrikova E A , Teresov A D , Tolkachev A S 
Published: January 2020

Abstract
The irradiation of hypoeutectic silumin 383.1 with an intense pulsed electron beam in the melting mode and rapid crystallization of the surface layer has been performed. A multiphase submicron nanostructured surface layer with a thickness of up to 70 nm has been formed. Mechanical tests of the irradiated silumin samples in tensile experiments have been carried out. A significant increase in strength and plastic properties of silumin irradiated with an electron beam has been established. Features and patterns in the distribution of displacement fields in the deformation process in surface layers of the samples in realtime have been identified by digital image correlation method using the optical measuring system VIC-3D.
Increasing Fatigue LIfe of 09Mn2Si Steel by means of High-Temperature Multistep Helical Rolling
Authors: Vlasov I V , Surikova N S , Panin S V , Yakovlev A V , Gomorova J F 
Published: January 2020

Abstract
The effect of high temperature helical rolling (HR) on structure and fatigue life of 09Mn2Si pipe steel has been studied. With the use of transmission electron microscopy there was revealed that rolling gives rise to refinement of ferrite grains and cracking (fracturing) of cementite plates within the pearlite phase. The effect manifests itself to the greatest extent in the surface layer where due to the rolling the level of plastic deformation was the highest. Data of microhardness measurements confirms the gradient pattern of strain hardening over the cross section during the HR occurs while the most intensive microhardness increasing take place at the depth of up to 3 mm. According to the mechanical testing results the helical rolling of 09Mn2Si steel gives rise to increasing the level of deforming stress at the yield plateau as well as the proportionality limit with a general decrease in the relative elongation. At the same time, despite the strain hardening resulting from the helical rolling the mechanisms of plastic deformation which manifest themselves in the form of parabolic hardening with a smooth decrease in the flow stress level after neck formation are preserved in the steel. During the cyclic tension the number of cycles prior to failure increases from 2.5 to 3.8 times that depends on the location of specimens’ cutting from the rolled rod. The highest improvement in fatigue fracture resistance is registered for specimens cut out from the core of the rolled rods.
Nonwoven PTFE Membranes Fabricated by Electrospinning Method: Preparation and Characterization
Authors: Kolesnik I M , Bolbasov E N , Buznik V M , Tverdokhlebov S I 
Published: January 2020

Abstract
Polytetrafluoroethylene (PTFE) is one of the promising materials for the purposes of tissue engineering and chemical technology because of its excellent physico-chemical properties and mechanical characteristics. However, conventional methods of PTFE porous membranes production have several disadvantages which limit the number of potential application areas by reason of a insufficient surface-to-volume ratio and poor porosity at small thickness. In the paper the results of using PTFE water suspension with a solution of water-soluble polymer for preparation of porous membranes by electrospinning are reported. The physico-chemical characteristics of membranes were investigated depending on the content of PTFE dispersion in spinning solution. There were found high hydrophobicity and lyophilicity of PTFE electrospun membranes. Main reasons of poor mechanical properties of porous membranes at high content of PTFE suspension in spinning solution are discovered. The ways of mechanical properties improvement and areas of possible applications are proposed.
Composition Polymeric Membranes Based on the VDF-TeFE Copolymer Formed by Electrospinning
Authors: Tverdokhlebova T S , Bolbasov E N , Bouznik V M 
Published: January 2020

Abstract
The paper presents the results of pilot studies on the formation of non-woven hydrophilic piezoelectric composite polymer membranes based on a copolymer of vinylidene fluoride and tetrafluoroethylene (VDF-TeFE) and polyethenylpyrrolidine (PEP) by electrospinning. Using optical goniometry, the effect of the PEP content on the wetting of the membrane surface with water was established. Using scanning electron microscopy, the influence of the content PEP on the structure of the formed membranes was studied. The effect of an isotonic NaCl solution on the structure of the formed membranes upon their dissolution within 7 days was studied. Based on studies of the chemical composition of the membranes before and after their dissolution, an assumption was made about the possibility of using the developed membranes for targeted delivery of pharmacological preparations for wound healing.
The Hydrothermal Synthesis Duration Influence on Calcium Phosphate and Hydroxyapatite Phase Composition
Authors: Chuprunov K , Yudin A , Leybo D , Lysov D , Kolesnikov E , Kuznetsov D , Godymchuk A , Mandal A R 
Published: January 2020

Abstract
This paper reports the hydrothermal synthesis process duration influence on phase composition, crystallinity degree, morphology and dispersity of the hydroxyapatite powder. The calcium phosphate and hydroxyapatite were synthesized in precursor system Ca(NO3)2-(NH4)2HPO4-NH4OH. The obtained powders were characterized with X – Ray diffraction, Fourier Transform spectroscopy (FTIR) and Raman spectroscopy. The results demonstrate: the increasing of the synthesis time duration has no influence on the phase composition. However, the synthesis duration time growth from 12 to 48 hours make possible increase the crystallinity degree from 0.68 to 0.98.
Effect of Surface Burnishing Treatment on Microstructure and Wear Performance of ZK60 Magnesium Alloy
Authors: Zhang Haiquan , Liu Yichen , Guo Peiquan 
Published: January 2020

Abstract
In order to improve the surface properties of high strength magnesium alloy ZK60, the surface burnishing treatment was carried out. The effects of burnishing process parameters on surface roughness, microhardness and microstructure of ZK60 magnesium alloy were studied. And the wear performance of the untreated and the surface burnishing treated samples was compared and analyzed. A gradient microstructure layer of nanocrystalline, ultrafine, deformed and original coarse grains from the treated surface to the matrix was formed on ZK60 alloy by surface burnishing treatment. In comparison with the untreated sample, the surface roughness of the burnishing treated sample was significantly reduced and the surface microhardness was evidently improved. After surface burnishing treatment, the wear of ZK60 sample decreased by 44.58%, and the friction coefficient decreased from 0.328 to 0.293, significantly improving the wear performance.
Preparation and Characterization of Submicron TiO2 Microspheres via Urea-formaldehyde Template
Authors: Lin Shaosen , Du Shiguo , Lu Yanling 
Published: January 2020

Abstract
In order to obtain sub-micron TiO2 microspheres with good dispersibility and easy collection, urea-formaldehyde(UF)-TiO2 hybrid microspheres were synthesized by polymerization-induced precipitation in acidic TiO2 sol through the reaction of urea and formaldehyde. The hybrid microspheres and their calcined products were analyzed by scanning electron microscopy, laser particle size analyzer, thermogravimetric analyzer and X-ray Powder diffractometer. The results of morphological characterization showed that the UF-TiO2 hybrid microspheres were spherical and well dispersed, and their particle size ranged from 0.8∼5μm The sub-micron TiO2 microspheres with large pore volume and good dispersion were obtained by calcining and removing the organic components in the hybrid microspheres. Thermogravimetric analysis showed that the proportion of inorganic components in hybrid microspheres was about 20%. XRD analysis showed that the product of calcined hybrid microspheres was single anatase-type titanium dioxide.
Analytic Solutions of Two-photon Rabi Model Based on Bargmann Space
Authors: Yan Zhanyuan , Yao Xuemin 
Published: January 2020

Abstract
The quantum Rabi model (QRM) is identified as the simplest model to study the interaction between light and matter. In recent years, Braak proposed an alternative more efficient method to obtain the exact solvability and spectrum of the QRM in the Bargmann space, which is appropriate frame for extended squeezed coherent states. Based on this feasible method, some study for the two-photon QRM is concentrated. In this paper we diagonalized the Hamiltonian and obtain the Spectrum of the system of two-photon QRM in the special case that the level splitting of the atom was equal to 0, and compared with Travĕnec’s results without diagonalizing the Hamiltonian. Finally, we confirm the validity of diagonalization for the Hamiltonian in the two-photon QRM.