Cross-sectional Dimensions Research Articles

Does international trade promote economic growth? Europe, 19th and 20th centuries

In this paper, we analyse the relationship between international trade and economic growth in an unbalanced panel of 20 European countries in a long-term perspective, since the mid-19th century to present days, differentiating between the periods before and after the start of the Second World War. To this end, we perform Granger-causality tests between exports and GDP, and between imports and GDP, following the novel methodology of Juodis et al. (2021) for panel data models with large cross-sectional and time series dimensions. Our results support the existence of a bi-directional relationship between both trade variables and GDP, for the whole period and across subperiods.

Measuring fatigue crack growth using microscale specimens: Si-modified Inconel 939 alloy processed by laser powder bed fusion additive manufacturing

Quantitative assessment of fatigue crack growth (FCG) in a Si-modified Inconel 939 alloy, processed by laser powder bed fusion additive manufacturing (L-PBF AM), was conducted through cyclic bending of pre-notched cantilevers with a characteristic cross-sectional dimension of 25 μm × 25 μm. To the best of our knowledge, this work is the first to show that cyclic bending of such pre-notched microscale cantilevers can sense both the threshold regime and the Paris-law regime of FCG quantitatively, despite the small specimen size. The deliberate fabrication of such microscale test specimens enables control of the direction of fatigue crack propagation with respect to a given microstructure, while avoiding the inclusion of volumetric defects within the test volume. Significant differences in FCG behavior were observed when the direction of crack propagation was switched from being parallel to the AM build direction to being perpendicular to it. The present work demonstrates the efficacy of FCG assessment using microscale specimens, which can enhance our understanding of the influence of a given microstructure on crack growth behavior.

An improved CSM-based design method for H-section aluminium slender columns under eccentric compression

This study proposed an improved design method for predicting the load-carrying capacity of H-section aluminium alloy slender columns under eccentric compression based on CSM. Through eccentric compression tests and extensive numerical simulations, the study explored the influence of cross-sectional dimensions, member slenderness ratios, and initial geometric imperfections on the load-carrying capacity of columns. The proposed CSM-based design method utilized CSM limiting stress and CSM buckling reduction factors tailored to aluminium alloy columns, accounting for the specifics of their material behavior and geometric properties. The comparison and evaluation of the load-carrying capacities predicted from the proposed design method, European design code, and American design code, as well as with experimental and numerical results, were conducted. Meanwhile, the reliability analyses on these design method and codes were also performed, adopting the method provided by the AISC and EN 1990, Annex D. The comparison and reliability analyses results indicate that, compared to existing design codes, the proposed CSM-based design method could provide more accurate, consistent, and reliable load-carrying capacities of H-section aluminium alloy slender columns under eccentric compression.

Effect of longitudinal reinforcement ratio on residual flexural capacity of high-strength reinforced concrete beams exposed to impact loading

In this study, it was aimed to investigate the dynamic impact and post-impact performances of high-strength reinforced concrete (RC) beams, which have different ductility and load-bearing capacities. The dynamic behavior and impact damages of RC beams were compared after exposure to a constant magnitude of impact energy. The applied impact energy was obtained by dropping a mass of 360 kg from a certain height of 3 m. The cross-section dimensions and length of the specimens were selected to carry out the experiments in full-scale. The tested specimens were designed with five different longitudinal reinforcement ratios for demonstrating distinct structural behavior mechanisms that vary from pure flexure to pure shear, representing different ductilities, load-bearing capacities and potential failure characteristics. The post-impact behavior of the impacted RC beams was also assessed by performing quasi-static bending tests on the impact-damaged specimens and the obtained results were compared with the identical undamaged reference RC beams. The results demonstrated that the longitudinal reinforcement ratio (which was intentionally designed for different specimens to exhibit different structural responses from pure shear to pure flexural and different shear-flexure mechanisms) significantly influences the dynamic response and damage intensity of the beams, which, in turn, affect their post-impact static performance. Key structural characteristics, including residual displacement, ductility, energy dissipation, load-carrying capacity, and stiffness, were analyzed. It was found that the mechanical properties of the beams deteriorated markedly after impact exposure. A crucial finding of this research is the notable shift in failure modes from flexural to shear after impact, depending on the damage severity. In RC beams, shear damage remains insignificant under both impact loading and subsequent static loading when the ratio of shear strength to flexural strength (Vr/Mr) exceeds 1.5. Conversely, when this ratio is less than 1.5, the behavior transitions to being shear-critical or shear-dominant. This study presents, for the first time, comprehensive experimental results on the impact-induced damage progression, failure mechanisms, and residual behavior of high-strength RC beams. These insights are vital for understanding the performance of RC structures under impact loads and contribute significantly to the field of structural engineering, particularly in designing impact-resilient structures.

Experimental and theoretical investigation on flexural behavior of concrete-filled tubular flange girders

Concrete-filled tubular flange (CFTF) girders offer superior torsional stiffness compared to traditional I-shaped plate girders, providing enhanced flexural performance. To accurately assess the flexural capacity of CFTF girders, both flexural tests and theoretical analyses were conducted on specimens with and without concrete decks. The experimental data were meticulously analyzed to understand the flexural mechanism, yielding sequence, interface slip, strain distribution, and confinement effect of CFTF girders. Subsequently, finite element models were then utilized to analyze the influence of cross-section dimensions and material optimization on the flexural behavior of CFTF girders. Comparative analyses with I-shaped girders were also performed to highlight the structural advantages of CFTF girders. The proposed flexural calculation formulas were validated against both experimental and analytical results, demonstrating a fitting accuracy between 95 % and 98 % for the yield moment and between 96 % and 98 % for the ultimate moment. The method proposed in this paper provides a reliable and accurate approach for evaluating the flexural capacity of CFTF girders, significantly contributing to the advancement of design and analysis practices in structural engineering.

Simulation and optimization on a novel air-cooled photovoltaic/thermal collector based on micro heat pipe arrays

To further enhance the performance of an air-cooled photovoltaic/thermal (PV/T) system, this study integrates micro heat pipe arrays (MHPAs) and serrated fins as the primary heat dissipation components. The lumped-parameter method was utilized to establish a mathematical model for the previously proposed PV/T system based on MHPAs. The model reliability was validated with the test data (errors within ± 10 %). Subsequently, the influence of solar irradiance, ambient temperature, airflow velocity inside the duct, and component structure on the air-cooled PV/T system performance was analyzed and optimized using the method of controlling variables. The impact of varying the condensing section length of the MHPA from 4 to 28 cm on the system performance was analyzed, and it was found that the condensing section length had a relatively small effect on the system thermoelectric performance. When the optimal comprehensive performance was achieved with fin heights ranging from 6 to 18 mm, heat collecting efficiency remained stable at around 19.5 %. When the cross-sectional dimension of the duct was 25 cm, the power generation efficiency reached its maximum value of 12.59 %. Such research findings provide data support for the promotion, development, and wider applications of air-cooled PV/T systems in energy utilization.

Three-Dimensional Computed Tomography Image Reformation for Comparison of Foraminal Cross-Sectional Dimension in Patients Who Have Undergone Laminoplasty and Laminectomy with Fusion [Acta Chir Orthop Traumatol Cech., 2024;91:103-108]

Three-Dimensional Computed Tomography Image Reformation for Comparison of Foraminal Cross-Sectional Dimension in Patients Who Have Undergone Laminoplasty and Laminectomy with Fusion [Acta Chir Orthop Traumatol Cech., 2024;91:103-108]

Development of Guidelines for the Design of Cantilevers

Cantilevers are elements typically used in the design of various structures such as factory halls or cantilever cranes. Traditionally, such elements are made of standard profiles or, in the case of large loads, by welding from standard sheets. Often, due to stationary conditions of exploitation, no attention is paid to mass reduction. Increasingly stringent requirements on reducing costs, but also on reducing environmental impact through reducing energy consumption necessary for the production, processing, and transport of materials, facilitate the application of optimization to obtain a construction solution with minimal mass. However, doing so requires advanced high-cost computer tools and increases the required competencies of designers. In this paper, a series of optimizations have been carried out for typical reach and load values of cantilevers aiming to create a database that will facilitate algorithms for selecting cross-sectional dimensions suitable for production using either additive technologies or traditional methods.

Ultrasonographic characteristics of myogenous temporomandibular disorders: A scoping review.

To identify the available evidence on the ultrasonographic characteristics of masticatory muscles in subjects with myogenous TMD, as well as the potential use of ultrasonography as a diagnostic and treatment assessment outcomes tool. An electronic search of the PubMed, Web of Science and Scopus databases was performed using the following terms: 'ultrasonography', 'ultrasound', 'masseter', 'temporal', 'masticatory muscles', 'temporomandibular disorders', 'temporomandibular joint disorders'. Full-text articles were obtained from the records after applying the inclusion/exclusion criteria. Thirteen articles were included for analysis: one comparative cross-sectional study, five case-control studies, six clinical trials and one randomised clinical trial. Main ultrasonographic characteristic assessed were local cross-sectional dimension and intramuscular ultrasonographic appearance. Retrieved studies reported the use ultrasonography for diagnosis or treatment assessment purposes showing heterogeneous results. For diagnosis purposes, the results of local cross-sectional dimension are not consistent; therefore, its diagnostic value for myogenous TMD diagnosis is weak. However, more homogeneous results were observed for intramuscular ultrasonographic appearance showing a higher prevalence of type-II pattern in myogenous TMD subjects than non-TMD subjects. On the other hand, for treatment assessment purposes, muscles were observed thinner after treatment compared to pre-treatment. Also, results of intramuscular ultrasonographic appearance show disappearance or reduction of anechoic areas, higher prevalence of type-II pattern and significant distinction of echogenic bands were observed after treating TMD subjects. Ultrasonography cannot be considered as a diagnostic instrument, but maybe as a complementary tool for treatment assessment of myogenous TMD subjects, even though future research is required to confirm its utility.

Post-fire behavior and residual resistances of S890 ultra-high strength steel circular hollow sections under combined compression and bending

This paper presents experimental and numerical investigations into the post-fire local buckling behavior and residual resistances of S890 ultra-high strength steel (UHSS) circular hollow section (CHS) under combined compression and bending. The physical testing was firstly conducted and encompassed heating, soaking and cooling of specimens, as well as post-fire tensile coupon tests, measurements of initial local geometric imperfections and eccentrically loaded stub column tests. Then, finite element models were developed and validated with reference to the experimental observations and then adopted for parametric analyses to derive additional numerical data, considering various cross-section dimensions and loading combinations. As a result of the lack of design provisions for ultra-high strength steel structures after exposure to elevated temperatures, the applicability of the relevant ambient temperature design interactive curves given in the current European, American and Australian standards to post-fire S890 UHSS CHS under combined compression and bending was assessed, with post-fire material properties used. The assessment results showed that all design standards exhibited conservative and scattered predictions of residual resistances for S890 UHSS CHS under combined compression and bending at ambient temperature and after exposure to elevated temperatures. The American specification provided more precise predictions of residual failure loads for non-compact and slender (Class 3 and 4) sections than the Eurocode and Australian standard, due to the accurate compression and bending endpoints. In comparison to the American and Australian specifications, the Eurocode resulted in more precise results in predicting residual failure loads of compact (Class 1 and 2) sections, owing to the accurate compression and bending endpoints as well as the nonlinear design interaction curve.

Robotic timber milling: accuracy assessment for construction applications and comparison to a CNC-machine

ABSTRACT The set goals of this paper consist of investigating the accuracy of industrial robots (IRs) when milling glued laminated timber and comparing these results to the machining accuracy of common CNC joinery machines (JMs). For the assessment, four different to-be-milled geometries, two positive and two negative shapes, were selected. In total, 45 specimens were milled, with eight of each geometry machined by the IR and the remaining 13 by a JM. In order to additionally consider the machining parameters of the JM in the assessment, two of the geometries were machined with different machining speeds. The dimensional analysis is based on 3D-scans of the specimens and the results have been checked in accordance with industry requirements. The results show that the median machining accuracy of the IR is very close to the robot manufacturer’s specifications of position and path repeatability. The accuracy of the JM lies insignificantly below the accuracy of the IR, however, presents wider-spread results. External influencing factors on the machining accuracy, such as workpiece alignment to the superordinate coordinate system and deviations of the raw workpiece cross-sectional dimensions, were identified allowing for a clear assessment of the true accuracy of both machining processes.

Features of determining the estimated length of positive arches made of laminated wood

The issue of loss of stability of arched structures is very important in engineering practice and design. This issue is especially key from the point of view of reliability and safety and economic losses, since structures of this type are usually used in buildings with a consequence class of at least CC2. [1].Laminated timber arches are long-span com-pression-bent elements in which the loss of stability plays a major role in determining the cross-sectional dimensions. In contrast to beams, an arch has a much larger ratio between the length of the element and its cross section, which in turn increases the risk of loss of stability. The loss of stability of an arch and its cor-rectly determined design length are directly related. The design length is defined as the value at which an arch can lose its stability under the influence of external loads. The main aspects of this relationship are: the value of the design length of the arch; mechanisms of loss of stabil-ity; dependence on the material and shape; ac-curacy of engineering calculations.It should be noted that recommendations for determining the design length of an arch are contained exclusively in the methodological lit-erature and outdated regulatory documents, such as [7]. In the latest current regulatory doc-ument [8], this issue is resolved by checking the strength and stability of the element, without limiting the flexibility. Since the flexibility of the element depends on its design length, the is-sue of determining this parameter remains open and relies directly on the design engineer, or rather, on his experience and competence. This issue is very relevant, given that a minor error in determining the design length significantly affects the results of testing compressed-bent elements.As a result of the work carried out, we analyzed the determination of the design lengths of hollow arches with different shapes and types of loading using two calculation methods: analytical formulas and the finite element method using the LIRA-SAPR-2019 software. Based on the calculations, recommendations for determining the design lengths of arches are given.

Seismic performance analysis and control method of composite coupled shear wall with steel plate-fiber reinforced concrete coupling beams

This paper based on the study of steel plate-fiber reinforced concrete coupling beam components, designs a basic model of composite coupled shear walls with steel plate-fiber reinforced concrete coupling beams. The seismic performance of this model was numerically simulated using the ABAQUS finite element software, analyzing the stress distribution of various parts and the development pattern of plastic hinges in the structure. It also examines how factors such as axial compression ratio, coupling beam cross-sectional dimensions, single-sided wall limb aspect ratio, and total floor height affect the seismic performance of this type of coupled shear wall, providing a reasonable range for axial compression ratios and coupling ratios for composite coupled shear walls with steel plate-fiber reinforced concrete coupling beams. Based on the obtained reasonable axial compression ratio and coupling ratio, and using the analytical solution of the continuum method, a method for controlling the seismic performance of coupled shear wall structures was proposed. Results show that the composite coupled shear walls with steel plate-fiber reinforced concrete coupling beams exhibit high load-bearing capacity and lateral stiffness under inverted triangular horizontal loads, with good displacement ductility and strong energy dissipation capability, making it an excellent seismic performance coupled shear wall system. As the axial compression ratio increases, the displacement corresponding to the yield point and peak point of the structure gradually decreases, and the displacement ductility coefficient shows a trend of first increasing and then decreasing; it is recommended that when designing steel plate-fiber reinforced concrete coupling beam-coupled shear walls, the axial compression ratio should not exceed 0.3. Numerical analysis of coupling ratio-related parameters indicates that in high-intensity seismic design areas, the range of coupling ratios should be between 45% and 60%.

Selection inconsistency for factor-augmented regressions

Factor-augmented regression (FAR) is an effective tool in forming predictions in the presence of big data set. However, few studies have considered the selection of latent factors and observed covariates simultaneously in FAR. We discover that the class of information criteria suggested by Groen and Kapetanios (2013) to determine the factors and covariates fail to provide consistent model selection, especially when regressors are correlated and the cross-section dimension is small relative to the sample size. This theoretical discovery is corroborated with simulation findings that the criteria in Groen and Kapetanios (2013) tend to underestimate the factor number but overestimate the covariate number.

EFFICIENCY OF USING FIBER CONCRETE AS CORE FOR STEEL CONCRETE COLUMNS OF SQUARE CROSS SECTION

The article examines the effectiveness of using fiber concrete as a core for reinforced concrete columns with a square cross-section. For this, at the first stage, the calculation of a steel-concrete column with dimensions of 100×100×3 mm, length of 500 mm was carried out using as a core a cross-section of concrete grade C20/25. At the next stage of the research, based on the conditions of the same bearing capacity of the columns, cross-sections were selected using fiber concrete with steel and basalt fibers at different values of the thickness of the steel shell. Steel fiber "Chilyabinka" was used, which was introduced at the rate of 32,536 kg/m3 of concrete. Basalt fiber was used with a length of 12 mm, and was added in the amount of 0.2% of the mass of cement. The dependence of the area of the concrete core and the area of the steel shell on the thickness of the steel shell is plotted. A comparison of the cost and characteristics of reinforced concrete columns with the use of ordinary concrete and fiber concrete with two types of fibers as a core cross-section was also carried out: steel and basalt. Based on research, the following conclusions can be drawn that the use of fiber concrete as the core of a steel concrete column of rectangular cross-section significantly improves a number of characteristics. Thus, with the same bearing capacity and thickness of the shell, the cost of a column with a core made of steel fiber concrete is reduced by 15%, weight by 26%, cross-sectional size by 13% compared to concrete without fiber. The cost of a column with a core made of basalt fiber concrete is reduced by 12%, weight by 21%, cross-sectional size by 9% compared to concrete without fiber. By changing the thickness of the steel shell, you can also influence the characteristics of the column, in particular, reduce the cross-sectional dimensions and weight. But at the same time, the cost of the column increases. Keywords: fiber concrete, steel concrete, column, bearing capacity

Wind load simulation for the analysis of the antenna dual-purpose poles aerodynamics

Introduction. In addition to the location of cellular communication equipment, dual-purpose poles perform the function of a lighting pole. Since dual-purpose pole are located on the central streets of the city, they have strength margins and minimum dimensions. The growing number of urban dual-purpose poles makes the correct calculation very relevant for ensuring their safe operation.Aim. Analysis of the change in the wind load on the dual-purpose pole with panel antennas and its effect on the strength of the dual-purpose pole structure. In order to achieve this, the following tasks were formulated: to deter-mine the dependence of the aerodynamic coefficient and the magnitude of the wind load on the dimensions of panel antennas and their location; to formulate recommendations for the installation of panel antennas on the upper dual-purpose pole section with a diameter of 114 mm.Materials and methods. An analysis of changes in the wind load and aerodynamic coefficient of the dual-purpose pole section, 114 mm in diameter, with panel antennas, installed thereon, depending on the dimensions of antennas and their location.Results. The aerodynamic coefficient was established to decrease at an increase in the projection of the panel antennas beyond the pipe rack, regardless of their dimensions. The more the panel antennas are pressed against the pipe rack, the closer they are to the neighboring antennas, thereby making it difficult to blow the cross-section in the center. Despite the fact that the aerodynamic coefficient decreases with an increase in the projection beyond the pipe rack, the value of the wind load remains almost constant.Conclusions. Panel antennas on a pipe rack with a diameter of 114 mm must be designed taking into account the cross-section dimensions of panel antennas. If the panel antenna width and thickness exceed 350 and 150 mm, respectively, the installation of such panel antennas should be as close as possible to the considered pipe rack in order to reduce the wind load on the dual-purpose pole. In other cases, the projection of panel antennas will have no significant effect on the change in the wind load.

Numerical Simulation Study on the Deformation Patterns of Surrounding Rock in Deeply Buried Roadways under Seepage Action

To reveal the deformation patterns of the surrounding rock in deeply buried straight-wall arch-shaped roadways under seepage action, this study, based on an FLAC3D numerical simulation and classic elastoplastic theory, investigates the influences of surrounding rock classification, roadway burial depth, pore water pressure, and roadway cross-sectional dimensions on the deformation of surrounding rock. A multivariate regression prediction model for rock deformation was established based on the numerical simulation conclusions, and the correctness of the conclusions was verified through comparative analysis. Correlation analysis of various factors with rock deformation was conducted, ranking their impact as follows: pore water pressure > roadway burial depth > surrounding rock classification > roadway height > roadway width. The research results can provide guidance for the construction and support of deeply buried roadways under seepage action.

Experimental and numerical investigation of an additively manufactured sandwich composite bridge deck utilizing gyroid building blocks

This work investigates the integration of Additive Manufacturing (AM) techniques with cellular metamaterials integrated into composite sandwich beam systems. The study proposes an approach that combines composite materials for the face sheets with cellular structures using a Triply Periodic Minimal Surface (TPMS) Gyroid structure for the core to achieve maximum lightweight and load-bearing capabilities. The experimental and numerical campaigns were utilized for the material testing of 3D printing polymeric material reinforced with chopped carbon fibre (CF). To validate the composite sandwich structure, three bending experiments were conducted: (a) bending of the “core only” was performed to calibrate the material for the given print parameters; (b) bending of the “sandwich beam” composite with a periodic and homogenous Gyroid core bonded with glass fibre reinforced polymer (GFRP) face sheets; (c) the “arch beam” composite with the change in outer cross-section dimension with the same periodic and homogenous Gyroid core. The FEM analysis was combined with Digital Image Correlation (DIC) results to determine the bending stiffness of the sandwich beams and to detect the failure modes. It was discovered that integrating 3D printing into load-bearing structures through the composite “sandwich beam” system resulted in seven times increase in load-bearing capacity and four times increase in stiffness compared to results obtained with the “core only” structure.

Investigation on the Torsional–Flexural Instability Phenomena during the Bending Process of Hairpin Windings: Experimental Tests and FE Model Validation

Modern electric motors developed for the automotive industry have an ever higher power density with a relatively compact size. Among the various existing solutions to improve torque and power density, a reduction in the dimensions of the end-windings has been explored, aiming to decrease volume, weight, and losses. However, more compact end-windings often lead to complex shapes of the conductors, especially when preformed hairpin windings are considered. The rectangular cross-section of hairpin conductors makes them prone to deviating out of the bending plane during the forming process. This phenomenon, known as torsional–flexural instability, is influenced by the specific aspect ratio of the cross-section dimensions and the bending direction. This study focuses on understanding this instability phenomenon, aiming to identify a potential threshold of the cross-section aspect ratio. The instability makes it difficult to predict the final geometry, potentially compromising the compliance with the geometric tolerances. A finite element model is developed to analyse a single planar bend in a hairpin conductor. Various cross-section dimensions with different aspect ratios are simulated identifying those that experience instability. Moreover, an experimental campaign is conducted to confirm the occurrence of instability by testing the same single planar bending. The experimental data obtained are used to validate the finite element model for the tested dimensions. The aim is to provide designers with a useful tool to select hairpin geometries that are more suitable for the folding process, contributing to successful assembly and improving the overall design process of preformed hairpin conductors.

Optimization of cross-sectional dimensions of castellated beams with hexagonal openings

The object of this study is a castellated beam, in which the web openings have the shape of a regular hexagon. The beam is examined to find optimal cross-sectional dimensions. The optimization task is stated as the task of finding the optimal profile numbers for top and bottom Tees of the beam and the optimal width of the web opening while ensuring the required load-carrying capacity of the beam. Minimization of the volume of the beam material was considered as an optimality criterion. The stated optimization problem was solved using the exhaustive search method. For an assortment of normal I-beams with parallel flanges, castellated beams were obtained with optimal cross-sectional dimensions depending on the steel grade, the beam span, and the magnitude of transverse uniformly distributed load. The optimization calculations proved that it was possible to increase the elastic section modulus of the beam to 35.48...50 % through the use of a castellated web. Castellated beams with optimal cross-sectional dimensions at the same load-carrying capacity are characterized by lower steel consumption (up to 23.19 %) compared to I-beams with a solid web. Analysis of the results has made it possible to devise recommendations for the optimal distribution of material in the cross-sections of such beams. The results are valid only for the assortment of normal I-beam profiles and only for the case of uniformly distributed load acting on the beam when the compressed beam flange is laterally restrained from the bending plane and the beam web has openings in the form of regular hexagons. It is under such conditions that the reported results can be implemented in practice both at the stage of selecting cross-sections of the studied class of structures, and at the development of effective assortments of castellated beams