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Machine learning techniques are potent tools to predict structural failures and forecast future failure patterns. They can provide insights that are not immediately recognizable to human operators, and hence, enhance the maintenance decision-making process, leading to better safety and longevity of structures. This research employed a genetic algorithm based on an identification technique to estimate the location and depth of cracks in circular arches. The arches were made of homogeneous material and had a rectangular cross-section. The study adopted two different procedures for detecting cracks in the circular arches. The first method used natural frequency contours represented in a three-dimensional plot to identify the location and depth of cracks by intersecting a set of natural frequency contours. The second procedure utilized the regression method and an optimization technique to minimize the cost function objective function and determine the crack parameters. The influences of crack location and depth on the vibrational behavior of cracked arches were presented and discussed. Similarly, the results indicate a high level of consistency between the two techniques in predicting both crack size and location. [ABSTRACT FROM AUTHOR]

The dynamic performance of a multi-column removal frame (MCRF) suffering from accidental impacts and uniform superstructure loads has largely been neglected in previous studies. To this end, a one-fifth scaled test model was set up to study the MCRF failure state and collapse mechanism. A numerical model was established and validated according to the collapse experiment. Parametric studies were conducted to investigate the effect of the impact height, heaped load (static uniform pressure on the slab), and frame storey on the MCRF dynamic response. The results indicated that: (i) the tension membrane, compressive arch and catenary effect were the main anti-collapse mechanisms in MCRF structures; (ii) according to the peak impact force under the increased collapse impact height (1.5 ∼ 2.5 m), a stronger local response and a slightly enhanced dynamic performance were successively presented on the hammer–concrete interaction; (iii) when the heaped load was increased, the structural plastic deformation capacity provided by the catenary action was better than that given by the compressive arch effect; (iv) the transient impact interaction was almost independent of the frame storey, but the MCRF anti-collapse performance was greatly affected by it. Finally, a collapse prediction method was given to evaluate the ultimate anti-collapse capacity of MCRF structures. [ABSTRACT FROM AUTHOR]

In this research, we are concerned with intraday volatilities computed by functional ARCH(1) (fARCH(1), for short) model for high-frequency financial time series. A conditional-Copula multiple change point detection (CPD) for intraday volatilities is proposed using fARCH(1), bivariate Gaussian Copula and t-Copula conditional distributions. We employ current available multivariate CPD models which include energy test based control chart (ETCC) and nonparametric multivariate change point model (NPMVCP) to implement the proposed CPD method for the intraday volatilities. A simulation study is conducted to demonstrate that the functional ARCH based conditional-Copula CPD for the intraday volatilities can be a useful econometrics method to detect abnormal intraday volatilities in the financial market. We analyze intraday volatilities of the Korea composite stock price index (KOSPI) and the Hyundai-Motor (HDM) company stock data with one minute high-frequency to illustrate our proposed CPD method. [ABSTRACT FROM AUTHOR]

The aim of this research is to investigate the impact of a viscoelastic foundation on the vibration of a curved beam structure with clamped and simply-supported boundary conditions. The structure considered is a micro-scale laminate composite beam made up of two piezoelectric face layers and a carbon nanotube-reinforced composite core. The study employs non-classical elasticity theory and nonlocal strain gradient theory to account for both nano-scale and microscale effects. The equations of motion are derived using the energy terms of the beam and a variational principle, with boundary conditions assumed to be clamped at one end and simply supported at the other end. A semi-analytical method of general differential quadrature method is used to solve the equations due to their nonlinear terms. To capture the effects of various parameters on the in-plane vibration of sandwich arches, an artificial neural network is designed and implemented. The study analyzes the impact of nonlocal and gradient parameters, geometrical aspect ratios, and substrate constants of the structure on the natural frequency and amplitude of vibration of the laminate beam. Results show that increasing nonlocal and gradient parameters have different effects on the amplitude and frequency of vibration of the beam. [ABSTRACT FROM AUTHOR]

Objective: The visual guiding system, as a tunnel traffic safety improvement method by using visual guiding facilities to actively guide driving safely, has been widely used in countries with many tunnels, in recent years. This paper aims to quantitatively study the comprehensive evaluation of traffic safety of the visual guiding system in tunnels, which has certain engineering application value and can provide support for the quantitative evaluation and optimal design of tunnel traffic safety. Methods: Based on the analysis of the relevant factors of urban tunnel traffic safety, a multi-factor comprehensive evaluation system with 5 upper-level indicators and 12 basic-level indicators was proposed. Considering the independent and incompatible indicators, a comprehensive evaluation method of traffic safety of the visual guiding system in urban tunnels was constructed by using the extension matter-element model. Taking the scene of 4 types of tunnel curves, such as no facilities, horizontal stripe, chevron alignment sign, and LED arch, as examples, the comprehensive evaluation of various schemes were carried out by using simulation tests. Results: The traffic safety comprehensive evaluation system of visual guiding system in urban tunnels can be analyzed from five aspects: perception reaction, guidance ability, driver factor, driving task, and facility appearance. The results demonstrated significant the comprehensive evaluation result of the target level of scene 1 was L4, scene 2 was L3, scene 3 was L2, and scene 4 was L1. That is, the final results of the comprehensive evaluation of the four scenes were poor, medium, good, and very good, respectively. Conclusions: In the scheme of visual guiding system for urban tunnel curves, the effectiveness of the three types of designs, from high to low, was the LED arch, chevron alignment sign, and horizontal stripe, and the safety of the scene without facilities was the lowest. Hence, setting the LED arch in the urban tunnel curve has a good effect in the aspects of guidance ability, sight distance, and sight zone, and is conducive to the driver's perception reaction and driving task. [ABSTRACT FROM AUTHOR]

The curved beam finite element approach based on the potential energy formulation is widely recognized as a versatile tool for lateral torsional buckling analysis of arches. However, there exist a variety of potentials, which were developed with distinct assumptions. The diversity of energy-based curved beam theories introduces confusions in practical applications. This paper aims to examine various potential energy formulations as to whether or not they obey the rigid body rule which is a prerequisite for valid second-order analysis. The induced moments at the ends of curved beam element that have been neglected from and/or the distributed moments that should be removed from available potentials are identified to help them become rigid body qualified. Based on the revised potential functional, a curved beam finite element formulation has been developed to effectively predict yet with less effort the out-of-plane critical load for circular and parabolic arches subject to various loading and constraint conditions. The results of numerical examples demonstrate that a potential energy formulation eligible for describing the out-of-plane behavior of curved beam is required to be rigid body qualified by fulfilling two aspects: (i) the neglected end moments that are imperative for satisfying the rigid body rule must be considered unless the virtual work done by them vanishes, and (ii) undesirable distributed moments that may be induced when undergoing the rigid body motion should be removed by considering all essential potential components. [ABSTRACT FROM AUTHOR]

The Partially Concrete Filled Steel Tube (PCFST) structure has gradually been applied to bridges as the main load carrying components in recent years, owing to the advantages of light weight and high stability. The failure mechanism and load carrying capacity of PCFST structure highly depends on the concrete filling ratio. For this purpose, the failure mechanism and parametric analysis of a single arched PCFST cable stayed bridge tower are investigated by using both refined solid element simulation and quasi-static experiment. The results shows that the PCFST arched tower experiences asymmetrical instability failure subjected to quarter span symmetrical loading, and the plastic hinges appears firstly at the tower arch closely above the tower columns, and then the bottom of the tower columns, forming a rotating mechanism leading to the instability failure. Filling concrete or not will result in two opposite deforming propagations of the plastic hinges, and when the concrete filling length exceeds the length of plastic hinge, the initial rigidity and ultimate load carrying capacity of the PCFST structure will sharply increase. Finally, according to the results of the extended parametric analysis based on the real size simulation, an improved initial stress reduction coefficient of PCFST structure is then suggested. [ABSTRACT FROM AUTHOR]

This work focuses on the bending examination of three-dimensional (3D) functionally graded carbon nanotube (CNT) reinforced composite (FG-CNTRC) cylindrical shell exposed to internal pressure. The composite cylindrical shell is assumed to be reinforced in the longitudinal axis. Mechanical properties of the constituents are applied based on the modified rule of the mixture. Distribution of CNTs across the shell thickness is assumed to be uniform and three types of functionally gradients. The governing equations are developed using the Principle of Virtual Displacements (PVDs) based on Carrera's Unified Formulation (CUF) and then differential quadrature method (DQM) is used to solve the governing equations for different combinations of simply supported and clamped boundary conditions. The comparison studies between the obtained results and those available in the literature demonstrate the accuracy and computational efficiency of the present formulation and method. The roles of different factors including the volume fraction of CNTs ( V CN * ), boundary conditions, distributions of CNTs, length-to-radius ratios ( L / r), and mechanical loads, are investigated in the outcomes. The results illustrate that the non-dimensional maximum deflections of functionally graded (FD) distributions are higher than the uniform distributions for different boundary conditions. [ABSTRACT FROM AUTHOR]

This article investigates the out-of-plane buckling of functionally graded porous I-shaped circular arches with graphene platelets reinforcements in a uniform temperature field. The accurate expressions of the prebuckling internal forces owing to thermal expansion are derived. The theoretical out-of-plane buckling temperature difference is obtained by the Ritz technique and is verified by finite element results. Notably, with the asymmetrical distribution of pores along the height of the section, the monosymmetry parameter is considered in the out-of-plane buckling energy equation. The effects of graphene platelets weight fraction, porosity coefficient, and porosity distribution patterns on buckling temperature difference are analyzed in detailed. [ABSTRACT FROM AUTHOR]

For a 300 MWe anthracite- and arch-fired boiler with biased-swirling-secondary-air (BSSA) technology, the distribution law of gas/solid two-phase velocity in the furnace is obtained with the help of a 1:10 cold modeling experiment bench, and the combustion and NOx formation characteristics in the furnace are revealed by numerical calculation. The results show that, with the increase of over-fire air rate, the reflux velocity in the reflux zone under the arch decreases continuously, and when the main air flow from the furnace arch reaches the staged air region from the vent air region, the position of particle flow in the primary air turn upward is advanced, and the utilization rate of the space in the lower furnace will decrease continuously. In the regions of vent air and staged air, when the over-fire air rate increases from 15% to 25%, the maximum vertical velocity decreases by approximately 2 times, and the downward depth of air flow from the furnace arch decreases significantly. When the over-fire air rate is increased from 10% to 25%, the thermal resistance between the primary air of the burner and the high-temperature flue gas in the furnace center increases, the ignition of the primary pulverized coal air flow is advanced, the flue gas temperature in the center of the lower furnace is decreased. As a result, with the increase of over-fire air rate, the combustible content of fly ash increases continuously. Especially, when the over-fire air rate increases from 20% to 25%, the combustible content of fly ash increases significantly. With the increase of the over-fire air rate, the high CO concentration region in the primary combustion zone expands, the reducing atmosphere is strengthened, the formation of NOx is effectively restrained, and the NOx emission concentration at the furnace outlet continues to decreases. In particular, when the over-fire air rate increases from 15% to 20%, the NOx emission concentration decreases greatly. After the swirling secondary air of the arch-fired boiler is biased, the setting of over-fire air rate is recommended to be 20%, and the NOx emission concentration and combustible content of fly ash are 694 mg/m3(O2 = 6%) and 7.32%, respectively. Compared with a traditional swirling arch-fired boiler, the combustible content of fly ash and NOx emission concentration are reduced by 46.8% and 34.1%, respectively. [ABSTRACT FROM AUTHOR]

AbstractTesting for the autoregressive conditional heteroscedasticity (ARCH) effect is an important problem in economic and financial time series. In this article, we consider the ARCH effect test for high-dimensional time series. Our test statistic is built based on the maximum element of Spearman’s rank correlation at different lags. The bootstrap methods are used to approximate the null distribution of the proposed test statistics. We also consider the goodness-of-fit test for ARCH models by applying the test to the residuals of fitted models. Simulation results show that the proposed test statistics enjoy good properties of size in finite samples. Compared to the existing methods, the new test possesses much better power. Moreover, the test is not sensitive to the underlying distribution of the time series. The proposed method is illustrated via two real data. [ABSTRACT FROM AUTHOR]

In the present exploration, the unconventional tensors of nonlocal stress and couple stress are incorporated simultaneously in the in-plane nonlinear stability analysis of functionally graded (FG) multilayer shallow micro/nano-arches under thermomechanical loading conditions. For this purpose, the nonlocal couple stress (NCS) mechanics of continuum is implemented into the third-order shear flexible arch theory incorporating the von Karman kinematical nonlinearity. The nanocomposite material of FG multilayer shallow micro/nano-arches is reinforced with graphene nanofillers in accordance with different patterns of FG lamination. The generalized differential quadrature numerical strategy in conjunction with the pseudo arc-length continuation procedure are employed to deduce the roles of unconventional nonlocal and couple stress tensors in the NCS-based nonlinear stability paths of thermomechanical loaded FG multilayer shallow micro/nano-arches. It is found that for all patterns of the lamination, the contributions associated with the nonlocality and couple stress small scale effects on the value of the upper limit as well as the first bifurcation compressive loads are less than those on the lower limit and the second bifurcation ones. Also, it is demonstrated that by combining a temperature rise with the applied compressive lateral load, the upper limit lateral load increases, while the lower limit one decreases. Furthermore, it is seen that by applying a temperature rise, an initial lateral deflection is induced in the shallow micro/nano-arch before applying the compressive lateral load. [ABSTRACT FROM AUTHOR]

Shield tunneling processes can result in accidents like water inrush and collapse due to instability in the tunnel face. This paper conducts a systematic investigation of the deformation features and failure mechanism of subsea shield tunnels with different burial depths crossing fault zone. The research entails combing theoretical analysis, numerical simulation, and data mining with the second subsea tunnel in Jiaozhou Bay, Qingdao. The impact of the shallow and deep burial depths on the damage modes of the shield tunnel face is analyzed from the perspective of the pressure arch effect. When the tunnel burial depth exceeds the limit, the overlying rock of the tunnel will form a pressure arch that supports the overlying rock. The study investigates the impact of various factors on the tunnel face's failure modes using a fluid-structure interaction approach. Among them, as the thickness of the overlying bearing stratum increased, the displacement of the tunnel face initially decreased but later increased. The increase of cohesion and internal friction angle contributed to decreasing the displacement of the tunnel face, while seawater depth and tunnel diameter exhibited diverse effects. In the grey correlation analysis, the seawater depth exhibited the most sensitive impact on the pressure arch height. [ABSTRACT FROM AUTHOR]

This paper reports on a numerical study focused on the characterization of the masonry and infill material behaviour of stone arch railway bridges. The study is based on experimental data from testing campaigns carried out in materials of two granite stone bridges. The campaigns comprise lab tests on stone masonry samples (blocks and joints) collected from the bridge structure, as well as in-situ flat-jack testing and Ménard pressuremeter tests on masonry and infill components, respectively. A strategy was developed resorting to Finite Element (FE) methodologies involving local scale numerical simulation of the joint lab tests (shear tests) and both in-situ tests (Flat-jack and Ménard pressuremeter tests), aiming at the calibration and validation of the material parameters to be used in global scale numerical simulations of the bridges' structural behaviour. The joint shear behaviour is simulated using a FE discrete formulation based on contact elements whereas the Flat-jack and Ménard pressuremeter testing is simulated using FE continuous homogeneous nonlinear materials based on a Drucker-Prager (D-P) model. The calibration of the D-P model input parameters is performed through a sensitivity analysis followed by an optimization strategy based on a genetic algorithm. The methodology showed the potential to calibrate the material constitutive parameters to be adopted in FE numerical models of this type of bridge. [ABSTRACT FROM AUTHOR]

When solving nonlinear algebraic equations that arise from discretization using the finite element method (FEM), it is often observed that the standard Newton-Raphson (N-R) iteration either fails to converge or necessitates a large number of iterations in the vicinity of critical points. This work proposes an additional numerical strategy, known as the Potra-Pták iterative cycle, to improve the efficiency of solving highly nonlinear structural problems. Therefore, the focus here is on making the nonlinear solver more robust and efficient, allowing the analysis of more complex nonlinear structures. In the Potra-Pták iterative cycle, two corrections of the objective function (energy function) are performed. The introduction of a second correction in the iterative cycle makes the Potra-Pták strategy more efficient than the standard or modified N-R iterations. This numerical strategy was implemented in the homemade Computational System for Advanced Structural Analysis (CS-ASA) program. The program is based on the FEM and is capable of performing static and dynamic nonlinear analysis of steel, concrete, and composite structures, and its efficiency is then verified through the analysis of slender frames and arches. The algorithm details for solving the nonlinear structural problem, characterized by the Potra-Pták scheme, are provided. [ABSTRACT FROM AUTHOR]

Taking a 300-MWe arch-fired boiler as the research object, compared with original Babcock & Wilcox (B&W) combustion technology, the flow, combustion and NOx emission characteristics are comprehensively revealed under the novel biased-swirl-secondary-air combustion (BSSAC) technology with the help of cold-modeling experiments and numerical simulations. The results show that, for BSSA combustion technology, the dimensionless downward depth of the air flow from furnace arches is increased by 0.13, and the air flow fullness of whole the lower furnace is improved under the effect of burner secondary air near the water-cooled wall, vent air and staged air being injected step by step. The high-temperature reflux zone and gas reflux velocity under the furnace arch increase significantly, the ignition of primary pulverized coal air flow is advanced, and the combustion path of pulverized coal particles increases. The combustible content of fly ash decreases by 32.4%. At the same time, the ignition process of pulverized coal air flow near the center of the furnace is in a strong reducing and low oxygen atmosphere, and the multi-stage effective air supply is obtained in the downward process of pulverized coal combustion. The NOx emission concentration at the furnace outlet is reduced from 824 to 694 mg/m3 (O2 = 6%). [ABSTRACT FROM AUTHOR]

AbstractThis research investigates, both experimentally and analytically, the mechanical performance of masonry specimens made with special lightweight concrete voussoirs joined with cement mortar and reinforced with TRM (Textile Reinforced Mortar) made of either fibreglass mesh, TRM with basalt mesh or FRPs (Fiber Reinforced Polymers). The specimens represent a segment of an arch. A total of 18 specimens were tested, with one-third featuring each reinforcement solution. Another variable studied was the number of sides reinforced with TRM or FRP, either one or three. The specimens were tested under eccentric compression to analyze the effectiveness of the reinforcements. An analytical model was calibrated with the experimental results and used to extrapolate the experimental results in terms of strength capacity. The specimens that exhibited the best mechanical behaviours were those reinforced with TRM using basalt mesh. The FRP reinforcement experienced prematurely debonding with the voussoirs. [ABSTRACT FROM AUTHOR]

In this study, a high-strength bolted prefabricated concrete beam-column junction is presented, and the prefabricated concrete beam-column joint parts are put through eight quasi-static tests. The axial compression ratio and the steel plate hoop thickness were used in extended parameter research using finite element software to completely examine the seismic performance of the construction. According to the findings, this node's ductility coefficient ranges from 2.57 to 3.69, which is bigger than 3. The specimen loses part of its bearing capacity and constantly loses ductility as the axial compression ratio rises. The failure displacement of the specimen decreases with an increasing axial compression ratio, but the yield displacement of the specimen is very slightly affected by the axial compression ratio. This node has an excellent energy dissipation capacity despite having a low viscous damping coefficient between 0.2 and 0.4, and when the axial pressure ratio rises, the capacity grows in response to the elevated pressure. Despite this, the energy consumption of the beam-column member is not significantly affected by the steel plate hoop thickness. Additionally, according to the variable-angle truss-arch model and taking into account the representation of the truss-arch model under different conditions, this paper presents the equation for the shear load capacity of diagonal sections of prestressed high-strength spiral hoop-restrained concrete beams under various conditions. [ABSTRACT FROM AUTHOR]

AbstractRobotic Hand Grasping is a challenging task that is studied by different researchers, with contributions made to topics such as grasping quality measuring, synthesis, and mathematical models. However, these works usually consider grasping of only one object at time, which is not applicable when the hand must carry multiple objects. Multiple objects grasping problem can be approached as a packing problem, which consists in filling a container with objects of a determined geometry, using the space available in the most efficient way. The aim of this work is to obtain a design methodology for a two-finger gripper that optimizes the grasping capacity of slender cylindrical multiple objects, applying packing problem concepts. This case is of practical importance in grapple claws used in forest harvesting for picking logs. A mathematical model is presented that allows to obtain an optimized geometric configuration of the grapple claw for maximum grasping capacity and packing density for given numbers and sizes of logs. This model is analytically solved for the maximum radius of a set of logs that can be grasped. Alternatively, for a number of logs with a given diameter, the geometric dimensions of an optimized grapple claw can be obtained. The solutions are evaluated using packing density and Active Force Closure (AFC) as quality metrics, to show the benefits of adding them as design criteria in the design multiple objects grapple claws. [ABSTRACT FROM AUTHOR]

There are many parameters that affect the seismic behavior of the bridge, especially in the new type of bridges. In this research, the seismic behavior of a cable-arch bridge as a new type of bridge with a hybrid system of an arch and stay cables has been studied considering the effect of seismic hazard probabilities and vertical excitations. By considering these parameters, the seismic analysis was investigated in three steps: Response spectrum analysis to obtain general seismic behavior of the bridge, time-history analysis using seismic ground motion records to capture dynamic responses, and pushover analysis to determine the capacity of the bridge. The performance of the bridge was monitored, and the significance of considering seismic hazard probabilities and vertical excitations was investigated. Pointing out the effects of these parameters on the seismic behavior of the bridge, the results indicated a requirement for considering them to provide the seismic safety of the bridge. [ABSTRACT FROM AUTHOR]

The current paper is focused on the frequency features of spinning coupled functionally graded carbon nanotube reinforced (FG-CNTRC) cone-cone shells undergoing high temperatures. The physic of the structures is based on two conical shell segments with different semi-vertex angles that are merges via the ideal bonding at the junctures. Simultaneous consideration of environmental thermal effects and rotation about the structure's axis in dealing with conditions near and also far from critical speeds and buckling temperatures could add the novelty of the available paper. The frequency inspections include the study of free vibration behavior, frequency bifurcation of traveling waves and also identifying instability regions with regard to critical thermal buckling and critical speed phenomena. A two-step procedure based on first order shear deformation theory (FSDT) and von Kármán assumptions is employed to access the system's formulation. Firstly, the initial thermal stress resultants are captured upon static step and then utilized through the dynamic step. Afterward, generalized differential quadrature (GDQ) method is implemented on the set of governing equations. After verifying the precision of results, some parametric studies are provided to investigate the effects of temperature and rotary speed elevations, radius and position of conjunction, CNT volume fraction and distribution schemes on the dynamic attributes of the spinning structure. [ABSTRACT FROM AUTHOR]

Structural safety assessments of ancient timber arch lounge bridges are necessary for determining the health statuses of these bridges and the urgency of any required maintenance. Based on the fuzzy comprehensive evaluation (FCE) method, we proposed a general method for assessing the structural safety of ancient timber arch lounge bridges. The proposed method comprehensively considers the structural safety of the sub- and superstructures of timber arch lounge bridges. Considering both qualitative and quantitative indicators in combination with the structural characteristics of timber arch lounge bridges, a comprehensive and systematic hierarchical assessment model was proposed. An objective method for determining the weight coefficients of the woven arch members was also proposed. In addition, a new fuzzy operator was proposed to improve the FCE method. The new fuzzy operator can consider the comprehensiveness of the relevant information and highlight crucial factors, thus improving the reasonability and accuracy of the assessment results. A case study was conducted to verify the feasibility and effectiveness of the proposed method. This study provides a quantitative structural safety assessment method for ancient timber arch lounge bridges and provides a reference for assessing the safety of other timber arch bridges based on the principle of polygonal arches. [ABSTRACT FROM AUTHOR]

This paper presents two different methods for folding a triangle onto a flat line by converting it into a Grashof Special Case fourbar linkage. Foldable triangles have many applications, ranging from space structures to collapsible furniture. In the first method, a generic triangle with positive real side lengths is shown to be foldable inward and outward by adding a pin joint at a specific location to one of the sides. The second method shows how to create a collapsible linkage using a Pythagorean triangle; we demonstrate that all four links in the Pythagorean fourbar have integer length and can be easily built using rods with uniformly spaced holes (e.g., LEGO bricks, Unistrut, etc.). Next, the formulas for finding the interior angles of the Pythagorean fourbar are presented, for the purpose of plotting collapsible structures with mathematical software. We conclude with a demonstration of a sample application of Pythagorean fourbars to collapsible arch or tower structures and a surprising proof that some types of collapsible arch structures are unrealizable with Pythagorean fourbars. [ABSTRACT FROM AUTHOR]

The present study investigates the relation between the optimal geometry (quantified via the minimum thickness) and the number of concurrent hinges at the masonry arch's limit state. The Heymanian assumptions regarding material behavior are adopted, and only constant thickness arches subject to static (i.e., self-weight) loading are considered. First, the only numerically verified completeness of the failure mode types (including 6 and even 7 hinges) of gothic arches is analytically proven. Next, it is investigated whether a higher number of hinges can concurrently occur for arbitrary, symmetric concave arches. A numerical procedure is presented which generates suitable arch geometries corresponding to a k-hinge mechanism, where k is an arbitrary odd integer not smaller than 5. For the generated class of arches, a higher number of concurrent hinges leads to lower minimum thickness values. However, it is explicitly proven that a higher number of hinges is not necessary for lower minimum thickness values. A small database about the geometry of the transversal arches of English and French medieval gothic cathedrals concludes the first part to allow comparison with the derived results. In the second part of the paper, existing literature results on the limit state analysis of gothic arches are extended by the effect of stereotomy on the failure mode type and minimum thickness value. [ABSTRACT FROM AUTHOR]

This paper is concerned with the Bresse system that arises in the modeling of arched beams. It is given by a system of three coupled wave equations that reduces to the well-known Timoshenko model when the arch curvature is zero. In a context of nonlinear elastic foundation, we establish the existence of smooth finite-dimensional global attractors, by adding dissipation mechanism in only one of its equations. In addition, we study the uniform boundedness of longtime dynamics with respect to the curvature parameter. These results have not been considered for partially damped semilinear Bresse or Timoshenko systems. [ABSTRACT FROM AUTHOR]

The article titled "Media Highlights" provides a concise overview of various publications and resources in the field of mathematics. It covers topics such as the first mathematics book printed in England, aperiodic monotiles, a card trick using a stacked deck, designing a corbeled arch, and a voting method called Majority Judgment. The text also discusses the historical impact of the Black-Scholes model on options trading, Anosov flows in mathematics, stochastic differential equations in golf performance modeling, counterproductive practices in mathematics education, and mathematical modeling of beach pebble formation. The article offers insights and recommendations for teaching math and understanding diverse cultural perspectives. [Extracted from the article]

The Great Wall is one of the most famous cultural heritages in the world. The defensive forts constitute the most important parts of the Great Wall. However, many of them have been severely damaged through the centuries, and their status requires a scientific evaluation. Taking the part of the Great Wall in the Yanqing district with 101 defensive forts as an example, on-site investigations were carried out and the main architectural forms, as well as the damage characteristics, were detected. Based on the architectural form analysis, a hierarchical quantitative evaluation system of the structural safety for the hollow defensive forts was established under vertical load. The grading criteria of crack and displacement indexes were obtained by using the elastic-plastic damage model through the finite element method. The weights of each layer index were calculated with the component importance method and the Analytic Hierarchy Process method. The component importance of the defensive forts is ordered as stone stereobate > brick stereobate > brick arch > flank wall > crenellation. Finally, four representative hollow defensive forts were chosen to demonstrate the proposed quantitative evaluation method. The research results can provide a preliminary screening method for conservation prioritization of the Great Wall forts. [ABSTRACT FROM AUTHOR]

As the demand for steel increased to supply military construction during World War II, Australian engineers began to push timber capacity for long-span structures, one of which led to the emerging use of glue-laminated timber-bending in the post-war period. This article analyses the laminated timber arches of three Ralph Symonds factories in Sydney, the ground-breaking laminated timber projects in Australia between the 1940s and 1960s. The study interprets the design reasoning behind timber-arch application and the structural reasoning behind timber bending using daylight simulation, structural simulation, and rule-based design analysis. The method used to formulate the rules is outlined and demonstrated. The study clarifies that Symonds's timber-arch designs evolved not only to accommodate space for medium to large-scale manufacturing activities but also to optimize economic, climatic, and structural constraints. The rule-based analysis reveals a consistent design logic applied across different factories, foregrounding Ralph Symonds's signature design language in laminated-timber arches. [ABSTRACT FROM AUTHOR]

The paper demonstrates how modern metric survey techniques and digital technologies can contribute to traditional methods of art-historical investigation. The original choir screen in the Dominican church in Cracow, spanning the width of the chancel arch, was built in the mid-13th century. An analysis of the laser scanning data of the existing church enabled a construction of a 3D model of the subsequent and larger choir screen, built in the second half of the 14th century, which extended across the nave and both aisles and encased the initial screen. A keystone decorated with a carved boss of unique iconography, interpreted as a symbol of St John the Evangelist, survives from the carved decoration of this screen. The 3D model of the choir screen helps to visualize the original location of particular altars, some tombs and surviving artworks within the screen porch. Its north bay housed the tomb of Hyacinth Odrowąż, the first Polish Dominican friar and future saint. In 1543 the north part of the screen's loft was cut off with a grille and transformed into a chapel of St Hyacinth, accessible to lay people by stairs running from the north aisle. The most important part of the chapel was a shallow niche which accommodated a new tomb and an altar with Hyacinth's relics. Construction from 1581 to 1583 of a new and more spacious chapel, located slightly higher than the old one, involved demolition of the choir screen. [ABSTRACT FROM AUTHOR]

In the Balkan Peninsula, the single-arched stone masonry bridge has served for centuries as an essential part of transportation infrastructure. Being exposed to the natural elements and to aging, several of these structures are in a state of disrepair that is accelerated by neglect. Nevertheless, these are important samples of the built heritage encapsulating historical materials, methods of construction and ancient craftsmanship. Still standing for over half a millennium, such bridges testify the wisdom by which the masons chose the location and form of the arch to span over torrents minimizing the wear from water scouring and floods. Preservation of the bridges that are still standing is a priority. With increasing number of bridge collapses reported in the past years under extreme flood, an immediate need emerges for methods of evaluation of the structural vulnerability and measures to enhance their resilience. Using as a case study a bridge built in fifteenth century in Greece, this paper unfolds the essential attributes of a comprehensive assessment framework that combines non-destructive evaluation techniques to reveal information about technologies and details, with a numerical investigation of the resilience of the structure to floods and seismic hazards in order to identify risks of bridge integrity. [ABSTRACT FROM AUTHOR]

An integer-valued ARCH process with a conditional zero-inflated binomial distribution is introduced. Stationarity, ergodicity and the autocovariance structure are studied as well as the estimation of parameters by conditional maximum likelihood. Numerical studies and an application to the number of hours in a day in which the prices of electricity for Portugal and Spain are different illustrate the performance of this model when compared with others. [ABSTRACT FROM AUTHOR]

He has also contributed as a consultant for major Public Works such as the Hong Kong - Zhuhai - Macao Bridge (longest sea-crossing project), the Xihoumen Bridge (longest span suspension bridge with box girder), the Shanghai Lupu Bridge (longest span arch bridge in China). B Zangmu Yarlung Zangbo River Bridge, I China i b Graph The bridge is a large-span concrete-filled steel tube arch bridge built in a high-intensity earthquake region. His fields of expertise are long-span bridge design, dynamics and aerodynamics, and wind resistance for bridges and structures. B Jialing River Three Bridges Project, I China i b Graph The three bridges of Jialing River in Nanbu County have a total length of 1.8km, of which the main bridge part is a continuous girder bridge with a total length of 695m, and the three-tower four-span short-tower extradosed bridge spans the Jialing River. [Extracted from the article]

Fair-faced concrete is a form of expression in architectural modernism. It does not add any decoration on the surface of the structure after pouring and forming, and takes the natural colour and texture of the concrete itself as the final design in order to integrate the building structure and achieve green energy-saving. A fair-faced concrete expression can reflect a clean, natural, solemn and simple personality of the building. However, because of its one-time forming and irreparable characteristics, fair-faced concrete is generally applied to conventional linear components, and technical bottlenecks for complex structures exist. As one of the largest fair-faced concrete structures in China, the Jingang Cultural Center includes a large number of complex-shaped fair-faced concrete structures. This report focuses on the structural characteristics of Jingang Cultural Center. Aiming at the representative components, such as a deepening design, mushroom body structure, ridge eave structure and arch-shell structure, a series of measures are studied, and a series of methods are proposed to improve the forming quality of fair-faced concrete with complex-shaped structures and enhance the feasibility and economy of fair-faced concrete in complex-shaped structures. [ABSTRACT FROM AUTHOR]

This paper extends the classical Glivenko–Cantelli theorem for the empirical cumulative distribution function based on the innovations in the ARCH model with a slowly time-varying trend. In this semiparametric time-varying model, L 1 strong consistency for the innovation density estimator via kernel smoothing method is established, given that the trend and ARCH parameter estimators meet some mild conditions. Besides, the strong consistency for the Gaussian quasi maximum likelihood estimator (QMLE) in the time-varying ARCH parameter is established as well. Moreover, in terms of the existence of the trend in the data, two major nonparametric trend estimators, B-spline and kernel estimators, are shown to be appropriate for the strong consistency results. [ABSTRACT FROM AUTHOR]

In this paper, the structural performance of masonry cross vaults is investigated with regard to the most common differential settlements occurring in historical constructions. Numerical parametric models are developed for vaults with different brick patterns and lateral constraints, in the presence/absence of infill. In particular, radial, diagonal and pitched brick patterns are taken into account and opening, shear and vertical settlements are analyzed. Moreover, the behaviour of laterally unconfined vaults is compared with the response of vaults restrained with rigid perimeter walls or with lateral masonry arches. The analyses highlight the strengths and weaknesses of each configuration, providing a scientific validation to some speculations found in historical technical literature on the most widespread use of some brick patterns. The outcomes of this research provide a deep knowledge of masonry vaults behaviour in view of more effective interventions on historical buildings, supplying the practitioners with a crack-pattern chart useful for better interpreting the damage pattern in historical vaults with different brick courses. [ABSTRACT FROM AUTHOR]

The new bridge across the deep gorge of the Chenab River in the remote mountains of Jammu and Kashmir is a key component of the Udhampur–Srinagar–Baramulla Rail Link (USBRL) project. The bridge is 1315 m long in total. Its main arch with a span of 467 m and land pier heights of up to 131 m place the bridge at an imposing 362 m above the river water level, making it the World's tallest railway bridge. Although the site location has been carefully chosen, yet the terrain itself is the most difficult from an engineering design and construction point of view. The slopes of the bank are very steep and consist of highly jointed dolomite strata. Extensive slope stabilization analysis was carried out and optimum measures were adopted and implemented successfully for slope stabilization works. The steel superstructure was erected using the incremental launching method. The report briefly highlights the various challenges faced in the project implementation and presents the most salient design aspects. [ABSTRACT FROM AUTHOR]

Conservation of the European-built heritage is nowadays closely related to interventions in masonry construction. Since a significant part of these structures are located in earthquake prone zones, designing protective measures that ensure their preservation requires the assessment of the associated seismic vulnerability and the understanding of their degradation mechanisms. However, due to the presence of discontinuities between its constituent elements, the numerical simulation of the non-linear response of masonry structures subjected to strong earthquakes is a cumbersome task, especially when performed using the traditional finite element method. As an alternative, the discrete element method is particularly suitable for the numerical analysis of such structures under large, damaging loads. By allowing discrete displacements/rotations of individual bodies, and by automatically recognising new contacts between bodies, while eliminating obsolete ones, this numerical approach can simulate the complete detachment of discrete bodies initially in contact. The present paper illustrates the use of the discrete element method to assess the seismic vulnerability of stone arches. A probabilistic approach allows to consider the variability of the seismic action and the uncertainties in the definition of the material properties. First, an un-reinforced masonry arch is considered. Based on non-linear multi-directional incremental dynamic analyses, five damage states are proposed and the respective fragility curves are elaborated. To improve the arch's seismic performance, two reinforcing solutions using steel elements are considered and analysed comparatively. [ABSTRACT FROM AUTHOR]

The snap-through analysis of shallow doubly hinged sinusoidal nano-arches subjected to sinusoidal load, considering the nonlocal effects, by using the stress-driven nonlocal model is concerned. The problem is formulated within the framework of Bernoulli–Euler beam theory including geometrical nonlinearity. Numerical simulations are made to investigate the effects of the geometry of the arch, and the nonlocal parameter on the buckling load and on the buckling deflection. Insights and conclusions regarding the effects of various stages of deformation on the stress resultants, and on the buckling including prebuckling and postbuckling are presented. Variations of the stress resultants along the arch are shown. [ABSTRACT FROM AUTHOR]

In this study, we investigate the development of an inchworm-inspired soft robot with active friction control of its feet. The focus is on its design, modeling, and locomotion principle. Friction control is achieved dynamically by using a unique material called double-network hydrogel (DN gel) to form the legs of the inchworm robot. DN gels are soft but tough materials, and they exhibit the unique characteristic of frictional difference on the surface under an applied voltage. This property is exploited to realize locomotion. A wide range of robot speeds can be realized through appropriate control of the voltage applied to its legs. Motion strategies with simultaneous control of actuation force and leg friction allow for greater flexibility in locomotion. The behavior of inchworm locomotion with change in the frictional difference between legs and actuator force was predicted using the developed mathematical model and was confirmed through experiments. Three different inchworm robot prototypes were developed and studied. The inchworm robot is characterized by low cost and inherent compliance, and it is easily disposable. [ABSTRACT FROM AUTHOR]

Historical masonry aqueducts were constructed to convey water over rivers, valleys, etc. Many of them have deteriorated due to different effects and may need to be repaired or strengthened to increase their load carrying capacities. Historical aqueducts are invaluable cultural heritage, and they require particular attention and appropriate seismic strengthening techniques including minimal intervention, better workability and reduced cost. The present study proposes filling the canal with water to improve structural seismic performance of historical masonry aqueducts. The influence of fluid–structure interaction in seismic performance improvement of historical masonry aqueducts is numerically investigated in this study. Three-dimensional (3D) finite element models of an aqueduct including without and with fluid–structure interaction are created using the coupled acoustic fluid–structure (CAS) approach. Concrete Damage Plasticity (CDP) material model adjusted to masonry units and ground motion records matched to site-dependent are utilized in the nonlinear seismic analyses. Seismic performances of the aqueduct models with and without fluid–structure interaction for the only-transverse, combined transverse and longitudinal, and combined transverse and longitudinal and vertical component cases are evaluated and compared with each other. [ABSTRACT FROM AUTHOR]

This study is appointed to discover the dynamic behavior related to one of the most applicable systems used in engineering, namely coupled beam bridge system. For this reason, the system, which is constructed by two circular arch beams and an elastic layer between them, is vibrationally investigated here. In addition, the geometrical strategy is hired to modify the essential position associated with the situation of the two beams lying on each other. Moreover, the first-order shear deformation theory (FSDT) and the cylindrical panel scheme are employed to discover the fundamental features of the relationships linked to the system. Moreover, by engaging Hamilton's principle and part-by-part integration (or Green–Gauss theory), the governing equations related to the motion of the system are achieved. Furthermore, the robust semi-analytical technique, renowned by the generalized differential quadrature operator is executed to split up the motion equations linked to the system. Additionally, to confirm the offered configuration, some benchmarks are chosen and solved. Finally, the influence of the diverse boundary conditions, geometrical characteristics, and different values related to the elastic mid-layer stiffness on the natural frequencies of the coupled circular arch–arch beam bridge system are determined. [ABSTRACT FROM AUTHOR]

Mingzhuwan Bridge is currently the largest span three-main-truss steel arch bridge, with a main span of 436 m. It was opened to traffic on 28 June 2021. The upper structure adopts a three-main-truss arch-beam combination system, the main arch is an N-type truss of variable height and the main girder is an N-type truss of constant height. The main girder truss is arranged with double decks, and the suspenders are made of high-strength parallel wire cables. The deck system adopts an orthotropic steel deck. This technical report mainly introduces the technical characteristics of the three-main-truss space truss structure, rigid arch and rigid beam structure, and synchronous construction of arch and beam. [ABSTRACT FROM AUTHOR]

This paper describes the design evolution and construction steps of Gravina (or "La Martella") Bridge, on S.S. 655 "Bradanica" Road, under the authority of the ANAS Department of Potenza, Italy. The final design of the bridge adopted the original solution for a "split" bowstring arch bridge first proposed by Arenas for Barqueta Bridge in 1992. Considering the cultural, historical and environmental heritage of the Gravina prestigious site, the bowstring arch type appeared to be perfectly in line with the contest of "La Martella" bridge. The bridge was re-designed later: the "as-built" solution shows some "adjustments" that were necessary to make bridge construction easier and to improve structural durability. To this end, although the original proportions were preserved, the original "split" arch was replaced by a couple of flanked and converging tubular arches, while a simpler composite deck was used instead of the original steel "boxed-reticular-open section". [ABSTRACT FROM AUTHOR]

The suplex is one of the most important and spectacular offensive moves in Greco-Roman wrestling, and wrestling in general, but to date no published biomechanical study has systematically described it. We performed a qualitative biomechanical analysis to classify variants of suplex, and to split this complex move into phases and actions within them. As suplex efficacy highly depends on speed of execution, we analysed 80 suplex throws from publicly available videos of international matches at the highest level to describe the duration of the different phases and actions, and how these vary across variants of suplex. We observed a preference for belly-to-belly vs belly-to-back and for lateral vs frontal variants of suplex. We show differences in duration of important phases/actions across variants, including the preparation phase (longer for belly-to-back variants) and the back arch in the projection phase (longer for frontal variants), while we find no evidence of a difference in the frequency of win by fall. Our study provides a useful framework to evaluate and monitor suplex execution, through information to help choose a variant in specific match contexts, a systematic description of its complex motion to allow a more focused training, and "gold-standard" durations of its movement components. [ABSTRACT FROM AUTHOR]

Financial returns are frequently nonstationary due to the nonstationary distribution of zeros. In daily stock returns, for example, the nonstationarity can be due to an upwards trend in liquidity over time, which may lead to a downwards trend in the zero-probability. In intraday returns, the zero-probability may be periodic: It is lower in periods where the opening hours of the main financial centers overlap, and higher otherwise. A nonstationary zero-process invalidates standard estimators of volatility models, since they rely on the assumption that returns are strictly stationary. We propose a GARCH model that accommodates a nonstationary zero-process, derive a zero-adjusted QMLE for the parameters of the model, and prove its consistency and asymptotic normality under mild assumptions. The volatility specification in our model can contain higher order ARCH and GARCH terms, and past zero-indicators as covariates. Simulations verify the asymptotic properties in finite samples, and show that the standard estimator is biased. An empirical study of daily and intradaily returns illustrate our results. They show how a nonstationary zero-process induces time-varying parameters in the conditional variance representation, and that the distribution of zero returns can have a strong impact on volatility predictions. [ABSTRACT FROM AUTHOR]

The material properties and bond-slip behaviour of the reinforced concrete beams during the period of the Republic of China (1912–1949) are different from those of modern reinforced concrete beams, so it is necessary to study the calculation method of the shear capacity of this type of beams. First, the material properties of the concrete and the square rebar, the bond-slip behaviour, and the failure mechanism of the beams were obtained in the tests by using square rebar during the period of the Republic of China(ROC) and concrete with the mix proportions of the ROC period. The results show that the ROC beam had a critical crack that propagates to the upper surface of the beam causing the beam failure. Then, a modified arch-truss model was proposed to quantitatively evaluate the relationship between the critical crack propagating process and the shear value, which is in good agreement with the test results. Finally, based on the calculation results of the modified model, a simplified trilinear model was proposed to determine the critical height of diagonal crack propagation in ROC reinforced concrete beams. The research results can provide a scientific basis for the shear capacity calculation and conservation of ROC reinforced concrete beams. [ABSTRACT FROM AUTHOR]

In this article, nonlinear analysis of pin-ended isotropic homogeneous deep arches under rapid heating is considered. Arch is subjected to thermal shock on one surface while the other surface is kept at the reference temperature. One-dimensional heat conduction equation across the thickness of the arch was solved analytically to obtain the temperature profile. The thermally induced bending moments and compressive thermal forces are evaluated from the temperature profile and inserted into the equations of motion of the arch. The equations of motion of the arch are obtained under the assumptions of uncoupled thermoelasticity laws, kinematic assumptions of a deep arch with considerations of geometrical nonlinearity and linear stress–strain–temperature law. By using the conventional multiterm polynomial Ritz method, the governing nonlinear equations of motion are discreted. The resulting nonlinear equations are solved via β − Newmark time marching scheme and Newton–Raphson linearization technique. Numerical results are presented to investigate the effects of different parameters. It is shown that thermally induced vibrations indeed exist especially for thin and shallow arches. As the arch becomes thicker or deeper, the thermally induced vibrations fade up and for sufficiently thick arches, quasi-static and dynamic responses of the arch become identical. [ABSTRACT FROM AUTHOR]

The present study takes advantage of a parametric model, which allows one to create automatically complex structural models of ribbed masonry vaults. Two numerical modelling strategies are discussed: a 3D continuum and a 3D contact-based model. The effects of settlements are studied by imposing vertical displacement at the vault supports up to collapse. Predictions of each modelling strategy are compared with actual damage observation. A representative square vault of Milan Cathedral is studied here, aiming to understand the causes of the damage documented through the years. The structure is noted to have suffered structural damage in the vaulting system due to a long history of soil settlements. The geometry is based on a photogrammetric scanning, and the three-dimensional solid models are created through parametric reconstruction procedures, including details such as springing, arch, ribs, web, and rubble-fill. Both modelling strategies allow to highlight the vulnerability of masonry vaults due to settlements. Significant differences in prediction capabilities are noted when large displacements and separation of elements are involved. The simulations show the possibility of predicting and interpreting different complex damage phenomena as arch block damage or sliding, and web–arch detachment, which is frequently observed in historical structures. [ABSTRACT FROM AUTHOR]

This paper investigates the structural response of unreinforced masonry arches subjected to asymmetrical vertical concentrated loads, by studying global force-displacement response curves and collapse mechanisms. The micromechanical modeling approach is adopted, which describes the detailed arrangement, geometry and mechanical properties of the masonry constituents. This is introduced in a 2D finite element procedure modified and enriched to describe masonry curved geometry and the occurring damage and friction mechanisms. Linear elastic behavior is assumed for bricks, whereas a damage-friction law is considered for the mortar to describe flexural and shear failure mechanisms. First, to prove the efficiency of the adopted model, the response of experimentally tested arches is numerically reproduced. Then, a parametric analysis is performed to analyze the effect of the geometric parameters on the global structural response. It is proved that, as the thickness/internal radius ratio increases, the failure mechanism moves from the formation of flexural hinges to shear sliding, leading to a more brittle response. Moreover, influence of relevant material parameters is investigated and the numerical outcomes are compared with those obtained by the classical limit analysis approach. It appears that the maximum predicted load generally exceeds the limit analysis collapse value, depending on the material properties mostly influencing the failure mechanisms. [ABSTRACT FROM AUTHOR]

The study of oval geometry domes encompasses a broad and interesting field of research that can be approached from multiple points of view. This paper shows the multidisciplinary approach developed for the analysis of the geometry of this type of domes from the architectural and mathematical points of view. This research paper focuses on the geometric study of the dome of the Camarín of the Virgin, of the Monastery of El Puig de Santa Maria (Valencia, Spain), an emblematic building of Valencian history and architecture. It begins with a survey by means of a multi-image photogrammetry and other surveying methods obtaining a point cloud that has served as a base for the geometric analysis. The approach to this analysis is through graphic and mathematical gradients, which allows to determine the graphic layouts and equations that best define the shape of the dome as well as drawing up a geometric construction hypothesis, which is consistent with the data. The conclusion obtained is that the dome is generated by an elliptical plan and five-centered oval arches in the vertical sections and the methodological process developed can applied to other cases. [ABSTRACT FROM AUTHOR]