Linear Elements Research Articles

As green infrastructure, linear semi-natural habitats boost regulating ecosystem services supply in agriculturally-dominated landscapes

Semi-natural linear landscape elements, such as hedgerows, are vital structures within agricultural landscapes that have an impact on ecosystem processes and support biodiversity. However, they are typically omitted from green infrastructure planning, which could lead to significant undervaluing of landscapes and their multifunctionality in terms of ecosystem service supply. Using the InVEST (Integrated Valuation of Ecosystem Services and Tradeoffs) model suite, we tested the effects of additionally including semi-natural linear landscape elements on the model outcomes for crop pollination, nutrient regulation, erosion regulation and water flow regulation ecosystem services supply. The results showed that linear semi-natural landscape elements contribute positively to the landscape’s multifunctionality. Small changes have been identified for water flow regulation, whereas, considering both spatial extent and magnitude of the changes, the greatest changes have been found with respect to the supply of pollination and nutrient regulation. Direct proximity of the linear elements had the greatest effect on ecosystem service supply, in particular with regard to pollination. Based on our results, a more pronounced consideration of semi-natural linear landscape elements as an important element of green infrastructure is advisable.

The battle plans in the 17th century on the example of the ‘ordres de bataille’ album by Eric Dahlbergh. Research model proposal

Abstract The article’s purpose is to present an original method of analysis of battle plans (orders of battle, battle orders, battle patterns, and battle settings) from the 17th century. We analysed 253 patterns from Eric Dahlbergh’s Album, which was a gift for King Charles XI of Sweden. In this text, we will take a look at the settings presented in Dahlbergh’s album. We hope that it will allow us to learn about the development process of the 17th-century arrays. What was the typical 17th-century order of battle like? Was it symmetrical or asymmetrical? How many throws and lines did it consist of? What was the ratio of the width to the depth of the army? Was the pattern composed of compact or linear elements? How did the formations (cavalry and infantry) stack up against each other? What was the frequency of intervals and higher tactical units? Thanks to the developed method, we obtained data for many patterns for the first time in history. They made it possible to characterize the patterns accurately and determine the time they changed. It is of paramount importance for the study of the European military in the early modern period.

A novel finite element approximation of anisotropic curve shortening flow

We extend the DeTurck trick from the classical isotropic curve shortening flow to the anisotropic setting. Here, the anisotropic energy density is allowed to depend on space, which allows an interpretation in the context of Finsler metrics, giving rise to, for instance, geodesic curvature flow in Riemannian manifolds. Assuming that the density is strictly convex and smooth, we introduce a novel weak formulation for anisotropic curve shortening flow. We then derive an optimal H^1 -error bound for a continuous-in-time semidiscrete finite element approximation that uses piecewise linear elements. In addition, we consider some fully practical fully discrete schemes and prove their unconditional stability. Finally, we present several numerical simulations, including some convergence experiments that confirm the derived error bound, as well as applications to crystalline curvature flow and geodesic curvature flow.

Full-scale testing of precast tunnel lining segments under thrust jack loading: Design limits and ultimate response

In modern practice, precast segmental tunnel linings are typically installed via a tunnel boring machine (TBM), which advances by thrusting against the previously installed segmental ring. The forces applied through the thrust jack pads can induce significant bursting and spalling tensile stresses and strains in the segment, and improperly designed segments can suffer from cracking as a result. An experimental study has been conducted to evaluate the progression of damage from initial cracking to ultimate capacity for full-scale precast tunnel liner segments under thrust jack loading. The baseline segment design is composed of steel fiber reinforced concrete (SFRC), and the impact of supplemental conventional steel bar reinforcement and load application eccentricity were also investigated. Six full-scale tests were performed with a thrust jack load per pad up to 22.2 MN (which is ∼ 3.8 times the maximum expected installation thrust force). At the maximum expected thrust jack load during installation (5.78 MN per pad), the segments were virtually undamaged, and hairline cracking initiated between the load pads on only one test. At the TBM’s ultimate jacking capacity (9.55 MN per pad) surface cracking was observed between and under the load pads; however, the crack width remained below 0.2 mm for all specimens. The formation of cracking limit states was accurately predicted by pre-test linear and nonlinear finite element (FE) models. At overload conditions, the baseline SFRC-only segment exhibited a radial bursting failure. The inclusion of supplemental conventional reinforcement does not reduce the level of cracking damage or strain development below the TBM’s ultimate jacking capacity; however, at overload conditions, the supplemental reinforcement mitigates cracking and prevents a radial bursting failure at 20.3 MN per pad. A load eccentricity of 38 mm towards the extrados surface increased the transverse strain and the formation of transverse cracking at a lower load level.

Evaluating the effect of natural-artificial linear landscape elements on flow and sediment connectivity in a typical agricultural terraced catchment, China

Linear landscape elements, such as man-made ditches and road networks, play a pivotal role in the transport of water and eroded sediments. Yet very few studies have focused on the variations in drainage flow paths disturbed by artificial linear landscapes and their contribution to flow and sediment connectivity (FSC). This study utilized the index of connectivity (IC) to examine and distinguish the impact of natural and artificial linear landscape elements (i.e., natural streams, man-made ditches, and road networks) on the spatial distribution of FSC. The method was employed in a typical agricultural terraced catchment of the Honghe Hani Rice Terraces World Heritage Site of China, based on two weight factors - roughness index (RI) and Rndvic factor. The results indicate that the incorporation of the linear landscape elements for the IC calculation remarkably affected the spatial distribution of FSC. Specifically, FSC values notably increased by closing the distance to linear landscape elements within a specific threshold. Moreover, in the confluence between natural and artificial linear landscape elements, the mean value of FSC was higher compared to scenarios without any or only one linear landscape element. In comparison, the presence of road networks only improved lateral connectivity by modifying the surface flow along east-west directions, while man-made ditches significantly influenced both longitudinal and lateral connectivity to a larger degree, especially in the terraced area. This finding underscores the effectiveness of ditch constructions as management practices for the regulation of water resources and facilitating the downstream transfer of sediment. Field observations and validation confirmed that Rndvic, which incorporates vegetation variable as a weight factor in the calculation of IC, yields more accurate and reliable maps of FSC than that of RI. This study holds far-reaching significance for water resources management and landscape sustainability within terrace-protected areas, providing invaluable insights for decision-makers.

Solid state thermal rectification by chemical pressure tuning of magnetic properties in perovskites

From an efficiency framework, waste heat generation and accumulation place significant limitations on how systems ultimately perform. Particularly, heat buildup leads to a significant loss of efficiency and subsequently system failure. In addition, current insulation and heat removal elements for supporting reliability and efficiency are robust and high power consumption systems that are based entirely on linear thermal elements instead of non-linear elements that would allow a unidirectional heat regulation process, thereby avoiding heat accumulation. In this sense, thermal rectifiers have recently attracted considerable interest due to their ability to manage heat unidirectionally. In this work, with the aim of exploring the potential of perovskites in thermal rectification, the magnon mediated thermal transport in the system La0.7Sr0.3Mn1–xCoxO3 (0 < x < 0.1) obtained by the solid-state ceramic route is investigated. Interestingly, results shows that thermal conductivity and Curie temperature substantially decreases with increasing of Co contents, which is attributed to the fact that positive chemical pressure is created due to smaller Co atoms take the place of some of the Mn atoms in the perovskite, shrinking the crystal structure. Taking advantage of those granted features, two-segment thermal diodes based on La0.7Sr0.3Mn1–xCoxO3/SiO2 have been implemented as a proof of concept devices. Experimental thermal transfer characteristics reveal that thermal diodes have markedly a nonlinear heat transport with rectification factors up to 2.3, meaning that devices control the heat flow via the deactivation of magnons through the Curie temperature; which in turn, controls accurately the on state of the device.

Microtubules oppose cortical actomyosin-driven membrane ingression during C. elegans meiosis I polar body extrusion.

During C. elegans oocyte meiosis I cytokinesis and polar body extrusion, cortical actomyosin is locally remodeled to assemble a contractile ring that forms within and remains part of a much larger and actively contractile cortical actomyosin network. This network both mediates contractile ring dynamics and generates shallow ingressions throughout the oocyte cortex during polar body extrusion. Based on our analysis of requirements for CLS-2, a member of the CLASP family of proteins that stabilize microtubules, we recently proposed that a balance of actomyosin-mediated tension and microtubule-mediated stiffness limits membrane ingression throughout the oocyte during meiosis I polar body extrusion. Here, using live cell imaging and fluorescent protein fusions, we show that CLS-2 is part of a group of kinetochore proteins, including the scaffold KNL-1 and the kinase BUB-1, that also co-localize during meiosis I to structures called linear elements, which are present within the assembling oocyte spindle and also are distributed throughout the oocyte in proximity to, but appearing to underlie, the actomyosin cortex. We further show that KNL-1 and BUB-1, like CLS-2, promote the proper organization of sub-cortical microtubules and also limit membrane ingression throughout the oocyte. Moreover, nocodazole or taxol treatment to destabilize or stabilize oocyte microtubules leads to, respectively, excess or decreased membrane ingression throughout the oocyte. Furthermore, taxol treatment, and genetic backgrounds that elevate the levels of cortically associated microtubules, both suppress excess membrane ingression in cls-2 mutant oocytes. We propose that linear elements influence the organization of sub-cortical microtubules to generate a stiffness that limits cortical actomyosin-driven membrane ingression throughout the oocyte during meiosis I polar body extrusion. We discuss the possibility that this regulation of sub-cortical microtubule dynamics facilitates actomyosin contractile ring dynamics during C. elegans oocyte meiosis I cell division.

“Come play with us!” A grassroots research agenda for accounting and the circular economy

ABSTRACT The dominant global capitalist economic model harms ecosystems and humxn populations. In attempting to reduce these harms, its linear foundational elements characterised by rapid production, mass consumption, and ineffective disposal necessitate a shift to more circular approaches. Embracing circularity is complex and requires several elements in addition to shifting business approaches such as redefining value, discarding traditional competitive practices in favour of collaboration, and developing appropriate tools for analysis. Given both its ubiquitous role in business and its ability to facilitate change, it appears a natural extension for accounting to serve an essential function in the circular transition. With this in mind, this editorial serves a twofold purpose. It first introduces the present special issue on “Accounting for the Circular Economy” and contextualises the circular economy concept. Secondly, it relies on insights from interviews with circular economy experts to propose a grassroots agenda for accounting within the circular economy context. Given the pressing need to address environmental and social challenges, we hope this editorial and the articles published in the special issue will spark further research and practical transformations toward a more regenerative and just economic and social system.

Grazing Bifurcations, Homoclinic Orbits and Chaos in a Ring Network of Linear Neuron-Like Elements with a Single Nonmonotonic Piecewise Constant Output Function

The bifurcations and chaos of a ring of three unidirectionally coupled neuron-like elements are examined as a minimal chaotic neural network. The output function of one neuron is nonmonotonic and piecewise constant while those of the other two neurons are linear. Two kinds of nonmonotonic output functions are considered and it is shown that periodic solutions undergo grazing bifurcations owing to discontinuity in the nonmonotonic functions. Chaotic attractors are created directly through a grazing bifurcation and homoclinic orbits based at pseudo steady states are generated. It is shown that homoclinic/heteroclinic orbits satisfying the condition of Shil’nikov chaos are caused by overshoot in the nonmonotonic functions.

Using Deep Neural Networks for Detecting Spurious Oscillations in Discontinuous Galerkin Solutions of Convection-Dominated Convection–Diffusion Equations

Standard discontinuous Galerkin finite element solutions to convection-dominated convection–diffusion equations usually possess sharp layers but also exhibit large spurious oscillations. Slope limiters are known as a post-processing technique to reduce these unphysical values. This paper studies the application of deep neural networks for detecting mesh cells on which slope limiters should be applied. The networks are trained with data obtained from simulations of a standard benchmark problem with linear finite elements. It is investigated how they perform when applied to discrete solutions obtained with higher order finite elements and to solutions for a different benchmark problem.

Use of Digital Elevation Models in Metallogenic Investigations on the Example of the Central Part of the Lower Amur Province

Abstract —The digital elevation model (SRTM03) of the central part of the Lower Amur province is analyzed. The Limuri–Amgun ring structure is identified on the basis of a set of features, and it is also the location of the Pilda–Limuri and Kherpuchin–V’yunsky gold-ore regions, as well as the Albazino deposit, known for large industrial gold deposits and many small deposits and ore occurrences. The distribution of linear and ring elements of the relief is analyzed and geologically interpreted, and its spatial relationship with gold deposits and ore occurrences is shown. The relationship between the morphological severity of the ring structure and the deep structure of the region is shown. It is revealed that the structure is magmatic and characterized by a high concentration of intrusive bodies. According to the reference data on the age and composition of the igneous complexes of the region, the formation of the ring structure is associated with the processes of formation and transformation of the Earth’s crust and upper mantle during the end of the Late Cretaceous and the onset of the Paleocene in a suprasubduction geodynamic setting.

Design of a separator machine for oil palm fruit mesocarp and nut using computer‐aided design and linear finite element analysis

AbstractThis study addresses the inefficiencies in the current palm oil milling process, where the coexistence of mesocarp fiber and nut during pressing results in oil loss and nut breakage. To tackle this issue, the research aims to develop a machine that can separate mesocarp fibers from nuts before pressing, enhancing oil extraction and quality. The study involves designing the machine layout, creating schematic drawings, wireframe models, and assessing stress and deformation performance. Solidworks simulation was used to determine stress and deformation points within material properties, dimensions, and applied forces. The maximum stress on the rotating disc was 1.44 MPa, with a total deformation of 9.75 x 10−4 mm. Comparing this to the static component strength against cracking (0.093 MPa) revealed that the disc's material and design can safely with stand loads, preventing deformation during the mesocarp and nut separation process. This innovation promises to increase oil yields and improve oil quality in palm oil milling.Practical applicationsThe separation of mesocarp fiber and nuts using centrifugal force is a feasible method. By removing nuts from the mesh (fiber) prior digestion and oil extraction process, the issue of nut breakage will be completely omitted, and thus the pressure can be further increased to maximize oil yield at the palm oil mill industries. This suggested approach has been demonstrated to produce a large amount of oil with minimal broken kernels. The crude palm oil obtained from this separation process also satisfies industrial standards.

Variability in parameter estimation for a tall steel-frame building

The between-event variability in identified shear wave velocities of fitted four-layer beam models in the response of a 54-story steel-frame building during nine earthquakes over a period of 27 years (1992–2019) is investigated. Recorded response and simulated response by its digital twin (linear finite element model with fixed base) were used as input, that is, the real structure and its digital twin were identified. Two surrogate models were fitted, a Timoshenko beam and a shear beam. The waveform inversion of impulse response functions method, developed earlier by the authors, was used to fit the beam models. The coefficients of variation (C.V.) of the between-events variability in the wave velocity estimates of the four layers were analyzed and compared for the different cases of data (real structure versus digital twin), different surrogate models, and different locations on the floor where the motions were observed. The results showed that the variability of the digital twin was affected by the contamination of the response by torsion, which is not accounted for in the beam models, by the degree of geometric regularity of the structure and by how closely the beam model represented the nature of the building deformation (balance of shear and bending deformation). These effects were minor in comparison to the nonlinear effects (recoverable nonlinearity and permanent stiffness degradation), which were not present in the digital twin response. The C.V. for the real structure (about 3%–5%) was comparable for both beam models fitted.

Supercloseness analysis of the linear finite element method for a singularly perturbed convection–diffusion problem on Vulanović–Bakhvalov mesh

Vulanović–Bakhvalov mesh is a kind of Bakhvalov-type mesh, which has the advantages of good numerical convergence and the transition point between coarse and fine mesh is not affected by mesh parameters. However, there is little theory of finite element methods for this mesh. In this paper, a linear finite element method on a Vulanović–Bakhvalov mesh is studied for a singularly perturbed convection–diffusion problem. In this process, some properties of the Vulanović–Bakhvalov mesh are obtained. Based on these properties and a new Lagrange interpolation, we further derive the supercloseness result of 3/2th order in an energy norm.

Investigation on smoothed finite element methods using linear tetrahedral elements for high-speed train hollow axle strength analysis

PurposeThis paper aims to investigate the performance of two novel numerical methods, the face-based smoothed finite element method (FS-FEM) and the edge-based smoothed finite element method (ES-FEM), which employ linear tetrahedral elements, for the purpose of strength assessment of a high-speed train hollow axle.Design/methodology/approachThe calculation of stress for the wheelset, comprising an axle and two wheels, is facilitated through the application of the European axle strength design standard. This standard assists in the implementation of loading and boundary conditions and is exemplified by the typical CRH2 high-speed train wheelset. To evaluate the performance of these two methods, a hollow cylinder cantilever beam is first used as a benchmark to compare the present methods with other existing methods. Then, the strength analysis of a real wheelset model with a hollow axle is performed using different numerical methods.FindingsThe results of deflection and stress show that FS-FEM and ES-FEM offer higher accuracy and better convergence than FEM using linear tetrahedral elements. ES-FEM exhibits a superior performance to that of FS-FEM using linear tetrahedral elements, showing accuracy and convergence close to FEM using hexahedral elements.Originality/valueThis study channels the novel methods (FS-FEM and ES-FEM) in the static stress analysis of a railway wheelset. Based on the careful testing of FS-FEM and ES-FEM, both methods hold promise as more efficient tools for the strength analysis of complex railway structures.

About the method of calculation of strength and durability of steel technological pipelines of high pressure

The article provides information on the methodology for calculating the strength and stability of a pipeline operating under conditions of high pressures and temperatures, taking into account the working pressure. According to the steel grade, the wall thickness of the selected linear section element was determined based on the initially specified resistances. Also, using modern software, a constructive model of the pipeline was built and its strength resistance from the action of specified loads was calculated. According to the results of the analysis, the suitability or unsuitability of the pipeline can be determined.

Deformation and Strength Characteristics of Marine Soft Soil Treated by Prefabricated Vertical Drain-Assisted Staged Riprap under Seawall Construction

Prefabricated vertical drains (PVDs) with staged riprap preloading have been widely used in soft soil ground improvement and embankment construction. However, ground treatment effectiveness evaluation is still a difficult problem due to multiple factors. Considering this, in situ monitoring and numerical simulation were conducted to study the deformation and strength characteristics of marine soft soil ground treated by PVD-assisted staged riprap under the Lingni Seawall construction in China. Monitoring and analysis of results showed that use of PVD-assisted staged riprap resulted in a good improvement effect. In particular, in the PVD-treated zone within 10 m in depth, corresponding to a half-length of the PVD, the average radial degree of consolidation reached up to 75–100%, and the soil strength increased significantly by 200–700%. Moreover, numerical simulation showed that the linear 1-dimensional drain element of PVD closely met the engineering accuracy requirements with good consistency with the monitoring data. Compared with a totally solid element model, the numbers of elements and nodes were reduced and the calculating efficiency and model accuracy were increased by using a PVD linear element, which provides a basis for building large complex finite element models.

An adaptive space-time algorithm for the incompressible Navier-Stokes equations

A space-time adaptive algorithm is presented to solve the incompressible Navier-Stokes equations. Time discretization is performed with the BDF2 method while continuous, piecewise linear anisotropic finite elements are used for the space discretization. The error indicator in time is justified through an posteriori upper bound of the error due to time discretization. The error indicator in space is taken from [1]. Numerical experiments confirm the sharpness of the error indicator and the efficiency of the adaptive algorithm.

A mixed finite element method for nonlinear radiation–conduction equations in optically thick anisotropic media

We propose a new mixed finite element formulation for solving radiation–conduction heat transfer in optically thick anisotropic media. At this optical regime, the integro-differential equations for radiative transfer can be replaced by the simplified PN approximations using an asymptotic analysis. The conductivity is assumed to be nonlinear depending on the temperature along with anisotropic absorption and scattering depending on both the direction and location variables. The simplified PN approximations are enhanced by considering a diffusion tensor capable of describing anisotropic radiative heat transfer. In the present study, we investigate the performance of the unified and mixed formulations combining cubic P3, quadratic P2, and linear P1 finite elements to approximate the temperature in the simplified P3 model. To demonstrate the performance of the proposed methodology, three-dimensional examples of nonlinear radiation–conduction equations in optically thick anisotropic media are presented. The obtained numerical results demonstrate the accuracy and efficiency of the proposed mixed finite element formulation over the conventional unified finite element formulation to accurately solve the simplified P3 equations in anisotropic media.

Finite element and isogeometric stabilized methods for the advection-diffusion-reaction equation

We develop two new stabilized methods for the steady advection-diffusion-reaction equation, referred to as the Streamline GSC Method and the Directional GSC Method. Both are globally conservative and perform well in numerical studies utilizing linear, quadratic, cubic, and quartic Lagrange finite elements and maximally smooth B-spline elements. For the streamline GSC method we can prove coercivity, convergence, and optimal-order error estimates in a strong norm that are robust in the advective and reactive limits. The directional GSC method is designed to accurately resolve boundary layers for flows that impinge upon the boundary at an angle, a long-standing problem. The directional GSC method performs better than the streamline GSC method in the numerical studies, but it is not coercive. We conjecture it is inf-sup stable but we are unable to prove it at this time. However, calculations of the inf-sup constant support the conjecture. In the numerical studies, B-spline finite elements consistently perform better than Lagrange finite elements of the same order and number of unknowns.