bluuebunny/crossref_metadata_2025_split huggingface dataset:
The High-Order Perturbation Approximate Solution of the Finite Ultrasonic Wave
Authors: Zhang Shigong , Zhang Kesheng , Su Xiangdong 
Published: August 2021

Abstract
To the nonlinear acoustic wave equation, the general used second harmonic solution is not accurate enough because all perturbated expansion equations higher than the second order are ignored during the equation solving process. The purpose of this paper is to obtain a more accurate solution, i.e., the high-order perturbation approximate solution. Firstly, the nonlinear acoustic wave equation is expanded into many inhomogeneous partial differential equations. the low-order harmonic solutions are obtained manually, then we formulate the form of the high-order harmonic solutions according to the properties of the low-order harmonic solutions. Using symbol calculation tool, we finally obtained higher up to the 14th order perturbation special solutions. Odd order solutions contain only odd order harmonics, and even order solutions contain only even order harmonics. The high-order perturbation solution of the second harmonic is finally achieved by summing up all of the second harmonic solution parts. The simulation results show that the relative amplitude (A
2/A
1) of the second harmonic increases and then decreases with the propagation distance, which is in agreement with experimental results. The high-order perturbation approximated solution can compensate for the theory deficiency and can be used to measure the nonlinear parameter with a good precision.
Morphological Group Theory of Soft Matter Structure - A New Mathematics of Natural Image Numbers
Authors: Zhou Ziqiang 
Published: August 2021

Abstract
The accurate understanding and interpretation of the SARS-CoV-2 electron microscope photos (EMP) is of great significance for the scientific treatment of coronary pneumonia and precise strategy. Here I study the image mathematics and physics description of micro-images of soft matter system by the morphology group theory of material structure, and show that there is a natural image numbers equation, which can be used to describe not only the common feature of soft matter structure, but also to correct classify the states into different classes, so that to study the morphology physics for soft matter science and biology, some important basic concepts of biophysics, such as the central dogma of molecular biology, Gene sequence analysis, heuristic recognition of SARS-CoV-2 can also be newly explained and understood by the equation.
Advanced container inspection system based on dual-angle X-ray imaging method
Authors: Lim C.H. , Lee J. , Choi Y. , Park J.W. , Kim H.K. 
Published: August 2021

Abstract
In 2007, the U.S. Congress mandated the implementation of the “Security and Accountability For Every Port Act of 2006,” which requires complete scanning of 100% of U.S.-bound shipping containers. To address this requirement, we developed a container inspection method that enables continuous high-speed screening, with considerable performance improvement. In this study, we developed a fixed-type high-precision container inspection system using dual-angle X-ray beams from a 9 MV linear accelerator (LINAC). We first calculated the X-ray irradiation angle-dependent changes in the contrast-to-noise ratio (CNR) of the images via Monte Carlo simulation. Using the calculated CNRs, the primary and secondary angles of the X-ray beam were set to 0° and 2.8°, respectively. A system based on the proposed dual-angle X-ray imaging technology was installed and evaluated by scanning a real cargo container truck. For the evaluation, we designed test equipment based on the ANSI N42.46 report and examined the beam penetration power, contrast sensitivity, spatial resolution, and wire detectability of the developed system. The maximum penetration thicknesses for the primary and secondary angle beams were found to be 410 and 400 mm, respectively. At the primary beam angle, the contrast sensitivities were 1.52% and 0.49% when the thicknesses of the steel plate were 80% and 50% of the maximum penetration thickness, respectively. At the secondary angle, the sensitivities were 1.88% at 80% maximum penetration thickness, and 0.5% at 50%. A line pattern formed by individual slits of 4.6 mm width could be easily recognized in an acquired image. In addition, the developed system could clearly identify a 1.6 mm diameter copper wire. Further, when a steel plate was added, the change in the wire-recognition ability of the imaging system was found to be similar at both beam angles. These results indicate that the developed system is suitable for container screening using a 9 MV LINAC. Shapes that could not be identified from one beam irradiation angle could more accurately be analyzed using images from two different angles.
Characteristics of bituminous shales used in asphalt mixtures
Authors: Hanganu D-Dr 
Published: August 2021

Abstract
Bituminous shales, bitumolites or pyrosists are sedimentary rocks impregnated with an insolvent bitumen. In Romania, studies have been carried out on bituminous shales by almost all Romanian geologists, starting with Cobâlcescu in 1877, continuing with Mrazec in 1907, Athanasiu in 1926, Popescu-Voiteşti in 1943, etc. In 1956, Nicolae Grigoraş was the one who made the first studies in detail on bituminous shales. Considering that the only norm on the basis of which the technological recipes for asphalt mixtures with bituminous sand are made, it underwent the last modifications in 1985, one of the specific objectives of the research was to update the technical specifications contained in the regulations in order to streamline the technological process associated with these mixtures and for a better implementation at national level of these practices. Without this long-awaited review, the use of this unconventional material would become more difficult, although it has both technical, economic and environmental benefits.
High-early strength concretes modified with polycarboxylate admixture on different cement types
Authors: Kryzhanovskyi V , Kroviakov S , Zavoloka M 
Published: August 2021

Abstract
Early and grade strength of modified concrete on different cement types (CEM II/A-S 42,5 and pozzolanic cement CEM IV/A(P) 42,5 R-SR) for concrete pavements repair was explored. Application range of the polycarboxylate modifier was 0.8-1.4% by weight of cement. All concrete compositions had equal workability (slump 5…9 cm). The aim of the investigation was to determine the optimal volume of the polycarboxylate modifier to achieve high strength indicators for repair material at the early and grade age.
High-strength concrete of grades C 50/60 and C 40/50 were obtained, with early strength at the 3 days age above 35 MPa, which allows them to be used as a repair concrete material for rigid road pavements.
X-ray phase analysis confirmed the positive effect of the polycarboxylate admixture in the structure formation of concrete. With an increase in the dosage of the BASF MasterGlenium SKY 608 admixture to 1.2…1.4%, the intensity of the diffractogram lines, which corresponds to the metastable hydration phase in the cement-sand matrix, decreased for concretes on both cement types.
Experimental and finite element modelling of prestressed hollow-core slabs
Authors: Moldovan I F , Nedelcu M , Heghes B , Constantinescu H , Buru S M 
Published: August 2021

Abstract
This paper presents the results of a study conducted on prestressed hollow-core slabs (HCS), both experimentally and numerically. The research has been carried out on real scale HCS manufactured at a local precast factory. The concrete specimens were prestressed using ten 12.9 mm diameter steel tendons placed both at the bottom and the top flange of the cross-section. They were tested under concentrated load until shear failure. Validation of the numerical results undertaken using ABAQUS 6.13 software demonstrated that the values obtained from the numerical simulation match the experimental ones in terms of force-displacement relationship.
FEM analyses on beam-to-column connection for a thin-walled cold-formed steel frame
Authors: Venghiac V M , Olteanu-Donțov I , Alexa-Stratulat M S , Țăranu G , Băetu S A , Toma I O 
Published: August 2021

Abstract
The advantage of fast construction for thin-walled cold-formed steel ground floor structures is somehow lessened by the challenges the engineers encounter when designing the connections. The horizontal forces induced by the seismic motions and not only, represent a serious threat to flexible structures. The paper presents the results obtained from comparative FEM analyses of different types and layouts of beam-to-column connection in case of a thin-walled cold-formed steel frame. The obtained results were analysed and compared from the point of view of maximum vertical displacements of the beam free end, the load-displacement diagrams as well as the principal stresses. The objective was to obtain the most efficient type of connection that ensures the safe transfer of internal forces from the beam to the column.
Seismic response of 1/2 scaled two storey reinforced concrete moment resisting frame system using nonlinear static analysis
Authors: Sococol I , Olteanu-Donțov I , Mihai P , Iftode V-I 
Published: August 2021

Abstract
Reinforced concrete (RC) frame systems represent one of the structural solutions used in seismic zones by engineers. For this reason, the importance of knowing the real seismic response for these types of structures is essential and presents the research problem studied in this article. Thus, the seismic response for two storey axial RC frame (one bay-one span) system was studied using nonlinear static analysis in ATENA software. The structural degradation of the two storey RC frame system was investigated for several steel reinforcement possibilities and three distinct RC beams cross sections. Particular attention was paid to RC beam-column joints degradation areas and to seismic energy dissipation mechanism in the marginal regions of the RC columns. Thus, it was observed a nonlinear inelastic response in the potential degradation zones with contrary effects with respect to the specified conclusions in the current seismic design norms. Also, it was studied the RC slab bending stiffness influence to horizontal structural elements (RC beams) and to vertical structural elements (RC columns) alongside the cracking mode for horizontal static actions and RC slab local degradation beside RC beam-column joint area. In these conditions, conclusions regarding the seismic response of the moment resisting (MR) RC frame system with low height regime designed according to the current seismic code were specified and an unsatisfactory seismic response was proved.
Numerical flexural strengthening investigation of timber-CFRP composite beams
Authors: Harrach D , Movahedi Rad M 
Published: August 2021

Abstract
Timber is among the most important construction materials with unique characteristics in comparison with other materials for instance steel and concrete. It is one of the first sustainable materials and continues to be a favoured selection in the current infrastructure. In the last decade, to refine the mechanical properties of timber, structural elements reinforcing fiber polymers have developed. In this study, to improve the flexural properties of timber beams, carbon fiber-reinforced polymer (CFRP) laminates are attached externally and internally between timber layers. For numerical simulations, first finite element model was validated according to the data obtained from experimental tests, then a series of simulations with different parameters were executed to investigate the flexural behaviour. The considered parameters include CFRP laminates’ existence and position. The linear elastic orthotropic material model was used to represent linear behaviour while the 3D anisotropic Hill material model was assumed to define the nonlinear behaviour of the material. Finite element simulations are executed by commercial software ABAQUS.
The socio-economic efficiency of computer-integrated transport modelling
Authors: Rakytska S , Kambur O , Zhus O 
Published: August 2021

Abstract
In the article has been analysed the possibilities of using modern digital technologies to optimize the transport system of a big city. The Urbanization’s processes lead to high rates of urban development, which provides for the creation of assorted transport supplying. However, there are situations when the geographic, landscape, natural and climatic area features, architectural solutions (characteristics) or blunders in the design of the city do not allow to create the road infrastructure of the necessary level. This leads to congestion of the main transport networks and generate traffic jams, increasing the degree of environmental pollution. The authors consider the horizons of creating a transport model of the Odessa city as an effective method of traffic management. It has been made out a case that the digitalization of the urban highways management reduces the trip time, alleviates the level of the road network congestion, increases the reliability and safety of transport, minimizes the number of non-standard traffic situations, and increases the economic efficiency of the city’s transport system. The using of powerful content solution allows you to build a mental (virtual) model, taking into account the actual traffic situation at this time and predict its changing when you have to make a certain management decision. This article is dedicated to the economic issue of the building a city transport model, the contemplation for its use to improve the efficiency of the city economy operation.
An analytical design approach for post-tensioned concrete slabs with unguided tendons
Authors: Toader T-N , Kiss Z , Țere S-G , Puskás A 
Published: August 2021

Abstract
This article contains practical information on the design and dimensioning of prestressed concrete solid flat slabs using unbonded post-tensioned tendons, in accordance with the European standard EN 1992-1-1 and German standard DIN 1045-1. The calculation method and the mathematical equations necessary for the dimensioning of the non-adherent unguided tendons are given. The paper presents a case study where a slab floor is dimensioned for deflection using prestressing only in the column strips. The deflection of the slab is calculated using equivalent loads (unguided tendon), a mixt tendon profile with 4th degree curve segments (unguided tendon) and parabolic tendon profile with 2nd degree curve segments (guided tendon-classical solution).
Seismic response of setback buildings with multiple underground levels
Authors: Gafincu C V , Mihai P , Lungu I 
Published: August 2021

Abstract
The topic of this paper exceeds the provisions of the present regulations concerning the structural design issues related to the connection or the behaviour of the setback buildings on slopped ground surface. Setback buildings means that the spans progress in a step-like succession from one side of the building along the entire length. Due to the increased number of buildings positioned on sloping ground this paper aims to highlight aspects related to the influence of a variable number of underground levels. This research follows the differences between the loading effects acting on three types of setback buildings that differ by the number of the underground levels (one, two, respectively three), on the length of two spans. The conclusions of the paper refer to the influence of the number of underground levels on the seismic response of reinforced concrete structural elements: columns, beams and walls. The obtained results are compared in the form of internal forces: axial force, shear force and bending moment. The structural modelling and analysis of the buildings have been performed by using ETABS software. In the end these results will show the influence of the number of underground levels in the alteration of the structural elements above ground in terms of material consumption.
Effects of chemical degradation on longitudinal fracture of non-homogeneous beams: an analytical study
Authors: Rizov V 
Published: August 2021

Abstract
An analytical study of the chemical degradation of the material and its effects of on longitudinal fracture behaviour of continuously non-homogeneous cantilever beam is carried-out. The chemical degradation is described by decreasing of the elasticity modulus of the non-homogeneous material with time. The fracture is studied by analyzing of the strain energy release rate. For this purpose, the strain energy release rate is derived as a function of time with taking into account the chemical degradation and the non-homogeneity of the material. The time-dependent fracture is analyzed also by applying the J-integral with considering the chemical degradation for verification. The variation of the strain energy release rate with the time due to the chemical degradation is studied and discussed in detail.
Delamination analysis of multilayered viscoelastic beam exposed to chemical degradation
Authors: Rizov V 
Published: August 2021

Abstract
Delamination of multilayered viscoelastic non-homogeneous beam structure subjected to chemical degradation is analysed in this paper. The creep behaviour is treated by using a linear viscoelastic model. The influence of chemical degradation is taken into account by decreasing the elasticity modulus and the coefficient of viscosity with time. The time-dependent delamination fracture under chemical degradation is studied by analysing the strain energy release rate. The strain energy is used to obtain the strain energy release rate that accounts for the creep and for the chemical degradation. The solution is verified by applying the compliance method with considering of the chemical degradation.
Numerical modelling of point thermal bridge’s impact on the thermal performance of facade systems
Authors: Moga L , Moga I 
Published: August 2021

Abstract
Starting with 31 December 2020 all new buildings, as well as existing ones, must comply with the nearly Zero Energy Buildings levels, as defined by each member state. A very important design criteria is the one regarding an accurate assessment of both linear and point thermal bridges of the building envelope. Usually, point thermal bridges are either not considered in calculations or are assessed by using simplified methodology as described by the standard EN ISO 6946/2017. This is due to the modelling and calculation complexity required in assessing them. Therefore, in several situations the impact is underestimated, and the thermal performance results do not offer a clear image of the building’s thermal performance. Thus, the paper focuses on the modelling and simulation of several constructive solutions for façade systems, aiming to identify a correlation between the geometrical and thermal characteristics of fixing components and the thermal performance of the facade. The studied case scenarios include two types of masonry walls, of 240 and 365 mm, that are thermally insulated in various thicknesses using an ETICS system. A sensitivity analysis is also performed to define a correlation between all the components that define the system and the point thermal bridge impact magnitude. The results of the study indicate an increased impact with a direct consequence on the energy performance of the building.
Computation and experimental considerations on dynamic testing of cement mortar
Authors: Alexa-Stratulat S M , Covatariu D , Toma I O , Covatariu G 
Published: August 2021

Abstract
Non-destructive tests to assess the dynamic characteristics of the materials are important for both in-situ and laboratory situations. Elastic modulus, rigidity modulus and Poisson ratio can be determined through dynamic testing, by employing resonant frequency measurements. The ASTM C-215 standard contains the necessary information for the experimental set-up and subsequent computation using the longitudinal, transversal and torsional frequencies, for both prismatic and cylindrical specimens. Nevertheless, some experimental particularities are not explained and their influence on the final results might prove important. In this paper, the experimental and computational insights on performing the dynamic Young modulus test for cement mortar prismatic samples, with emphasis on the importance of interpretation of the results are presented. The type of specimen support and the actual data manipulation, when extracting results, are taken into consideration. The results may prove important for the correct employment of dynamic testing.
Database assessment of the reinforced concrete water tanks built fund in Iasi county
Authors: Covatariu D , Filip A , Covatariu G , Toma I O 
Published: August 2021

Abstract
Reinforced concrete water tanks are special structures and important from a strategically point of view. In particular, they are degraded both at the exterior (aggressive environmental agents) and interior (chlorinated water). A case study based on a group of water tanks (over-ground, semi-buried, underground) which have been investigated / analysed in the period 2016-2020 was conducted based on the degradations / non-conformities identified (on site visits, in monitoring / technical expertise reports, etc.). In this regard, for each constructive type (also considering the exploitation period and storage capacity), certain types of degradations were identified. Taking into account the state of degradation of each objective studied / analysed, a scoring system was assigned. The aim of this article is to conceive an algorithm (following the analysis of the database) regarding the level of degradations for each constructive system and to propose the suitable rehabilitation procedures corresponding to the investigated water tanks.
Indirect determination of the measurement accuracy of the FMK-004 track geometry measuring car used on Hungarian rail network
Authors: Nagy R , Horvát F 
Published: August 2021

Abstract
During the examination of the Hungarian national network for the period from the 2nd half of 1999 to the 2nd half of 2013, had to answer to the reason why the geometrical errors are able to decrease, despite the fact that no regulation intervention was done on the line section during the study period. This anomaly leads us to the procedure in which it became important to determine the accuracy of the FMK-004 measuring car (FMK in English: railway superstructure measuring car). With the VBA code written for the research task, the data set was optimized, then deterioration functions were fitted to the data, and where outliers were detected, the extent of the outlier was analysed on a statistical basis. This determines the measurement accuracies for each of the three metrics separately. Furthermore, it can be clearly demonstrated by the examination of the national network that in 90% of cases there is a series of geometrics that have a value that decreases compared to the previous half-year, while other geometrics value still is increasing.
Seismic hazard mapping using R-CRISIS
Authors: Cutia E , Țurcan V 
Published: August 2021

Abstract
This article presents methods and software used to develop a seismic hazard map. As an example, the territory of the Republic of Moldova is being studied, which is affected by subcrustal earthquakes of medium depth in the Vrancea seismic area. The elaboration of the map is based on the theoretical model of probabilistic seismic hazard assessment established and described in detail in the specialized literature. In order to facilitate and minimize errors, specialized software was used, one of this software is R-CRISIS, a software created and presented for premier in 1986 by Professor Mario Ordaz at the Institute of Engineering UNAM, Mexico and which is continuously being developed and improved. R-CRISIS allows the users to perform a big range of deterministic and probabilistic analyses through a user-friendly interface.