Line Elements Research Articles

Determination of load transfer characteristics to connections between cold-formed steel truss and supporting system

PurposeRecently, the utilization of cold-formed steel (CFS) roof truss systems and different types of other combination structural support systems, such as concrete or hot-rolled steel support, becomes more frequently used. This paper aims to identify the load transfer characteristics of three different design details for cold-formed truss to supporting system connections and to propose simplified modelling approach for practices.Design/methodology/approachSimplification modelling of connection design could be proposed for practical purpose based on the load transfer characteristics obtained from detailed study using finite element method. A cold-formed roof truss system with connection is modelled using line elements. However, the supporting system is not modelled in this work. Three types of connection involve, which are five pieces of CFS L-angle brackets, one-piece of CFS L-angle brackets and three types of bolts connection are modelled.FindingsThe results of analysis show that the connections located on the loaded side experienced higher reactions than those far from loaded side. From the result, it is also found that the option of “Fixed But” support condition in STAAD.Pro with translational degree of freedom being restrained is the most suitable way to represent the CFS L-angle brackets design for Type 1 connection for use in truss modelled using line elements.Originality/valueSuch increase in usage necessitates an appropriate connection detailing depending on the behaviour of the connection.

Raster Map Line Element Extraction Method Based on Improved U-Net Network

To address the problem of low accuracy in line element recognition of raster maps due to text and background interference, we propose a raster map line element recognition method based on an improved U-Net network model, combining the semantic segmentation algorithm of deep learning, the attention gates (AG) module, and the atrous spatial pyramid pooling (ASPP) module. In the proposed network model, the encoder extracts image features, the decoder restores the extracted features, the features of different scales are extracted in the dilated convolution module between the encoder and the decoder, and the attention mechanism module increases the weight of line elements. The comparison experiment was carried out through the constructed line element recognition dataset. The experimental results show that the improved U-Net network accuracy rate is 93.08%, the recall rate is 92.29%, the DSC accuracy is 93.03%, and the F1-score is 92.68%. In the network robustness test, under different signal-to-noise ratios (SNRs), comparing the improved network structure with the original network structure, the DSC improved by 13.18–17.05%. These results show that the network model proposed in this paper can effectively extract raster map line elements.

On the Quaternion Transformation and Field Equations in Curved Space-Time

In this paper, we use four-dimensional quaternionic algebra to describe space-time geodesics in curvature form. The transformation relations of a quaternionic variables are established with the help of basis-transformations of quaternion algebra. We deduce the quaternionic covariant derivative that explains how the quaternion components vary with scalar and vector fields. The quaternionic metric tensor and the geodesic equation are also discussed to describe the quaternionic line element in curved space-time. We examine a quaternionic metric tensor equation for the Riemannian Christoffel curvature tensor. We present the quaternionic Einstein’s field-like equation, which indicates that quaternionic matter and geometry are equivalent. Relevance of the work:In recent decades, hypercomplex algebra, viz., quaternion and octonions, has been widely used to explain various branches of physics. In this way, we have investigated quaternionic transformations and field equations in curved space-time. The present novel work will help to explain the characteristics of the curved space-time universe in terms of quaternion algebra. It can also be used to describe quaternionic gravitational waves, the black hole formulation, and so on.

Hidden symmetries from distortions of the conformal structure

It is well established that the mass parameter breaks the conformal symmetries in the case of geodesic motion. The proper conformal Killing vectors cease to generate conserved charges when non-null geodesics are considered. We examine how the introduction of the mass is actually related to the appearance of appropriate distortions in the conformal sector, which lead to new conservation laws. As a prominent example, we use a general pp-wave metric, which exploits this property to the maximum. We study the necessary geometric conditions, so that such types of distortions are applicable. We show that the relative vectors are generators of disformal transformations and prove their connection to higher order (hidden) symmetries. Except from the pp-wave geometry, we also provide an additional example in the form of the de Sitter metric. Again, the proper conformal Killing vectors can be appropriately distorted to generate conserved quantities for massive geodesics. Subsequently, we proceed by introducing an additional symmetry breaking effect. The latter is realized by considering a Bogoslovsky type of line element, which involves a Lorentz violating parameter. We utilize once more the pp-wave case as a guide to study how the broken symmetries---this time also related to Killing vectors---are substituted by distortions of the original generators. We further analyze and discuss the necessary geometric conditions that lead to the emergence of these distortions.

Nonsingular spherically symmetric black-hole model with holonomy corrections

We present a covariant model of a spherically symmetric black hole with corrections motivated by loop quantum gravity. The effective modifications, parametrized by a positive constant $\ensuremath{\lambda}$, are implemented through a canonical transformation and a linear combination of the constraints of general relativity, in such a way that the theory remains free of anomalies and general relativity is recovered for $\ensuremath{\lambda}=0$. In addition, the corresponding metric is constructed in a fully covariant way to ensure that gauge transformations on phase space correspond to coordinate changes. The solution for each gauge choice provides a chart and corresponding line element of a spacetime solution whose geometry is unambiguously determined in terms of the parameter $\ensuremath{\lambda}$ and a constant of motion $m$. For positive values of $m$, the solution is asymptotically flat and contains a globally hyperbolic black-hole/white-hole region with a minimal spacelike hypersurface that replaces the Schwarzschild singularity. The corresponding exterior regions are isometric and, in particular, allow the computation of the Arnowitt-Deser-Misner mass. The procedure to obtain the global causal structure of the solution yields also its maximal analytic extension.

Analysis of repeat elements in the Pristionchus pacificus genome reveals an ancient invasion by horizontally transferred transposons

BackgroundRepetitive sequences and mobile elements make up considerable fractions of individual genomes. While transposition events can be detrimental for organismal fitness, repetitive sequences form an enormous reservoir for molecular innovation. In this study, we aim to add repetitive elements to the annotation of the Pristionchus pacificus genome and assess their impact on novel gene formation.ResultsDifferent computational approaches define up to 24% of the P. pacificus genome as repetitive sequences. While retroelements are more frequently found at the chromosome arms, DNA transposons are distributed more evenly. We found multiple DNA transposons, as well as LTR and LINE elements with abundant evidence of expression as single-exon transcripts. When testing whether transposons disproportionately contribute towards new gene formation, we found that roughly 10–20% of genes across all age classes overlap transposable elements with the strongest trend being an enrichment of low complexity regions among the oldest genes. Finally, we characterized a horizontal gene transfer of Zisupton elements into diplogastrid nematodes. These DNA transposons invaded nematodes from eukaryotic donor species and experienced a recent burst of activity in the P. pacificus lineage.ConclusionsThe comprehensive annotation of repetitive elements in the P. pacificus genome builds a resource for future functional genomic analyses as well as for more detailed investigations of molecular innovations.

The ecology of palm genomes: repeat-associated genome size expansion is constrained by aridity.

Genome size varies 2400-fold across plants, influencing their evolution through changes in cell size and cell division rates which impact plants' environmental stress tolerance. Repetitive element expansion explains much genome size diversity, and the processes structuring repeat 'communities' are analogous to those structuring ecological communities. However, which environmental stressors influence repeat community dynamics has not yet been examined from an ecological perspective. We measured genome size and leveraged climatic data for 91% of genera within the ecologically diverse palm family (Arecaceae). We then generated genomic repeat profiles for 141 palm species, and analysed repeats using phylogenetically informed linear models to explore relationships between repeat dynamics and environmental factors. We show that palm genome size and repeat 'community' composition are best explained by aridity. Specifically, Ty3-gypsy and TIR elements were more abundant in palm species from wetter environments, which generally had larger genomes, suggesting amplification. By contrast, Ty1-copia and LINE elements were more abundant in drier environments. Our results suggest that water stress inhibits repeat expansion through selection on upper genome size limits. However, elements that may associate with stress-response genes (e.g. Ty1-copia) have amplified in arid-adapted palm species. Overall, we provide novel evidence of climate influencing the assembly of repeat 'communities'.

Investigation of the influence of bundled conductor capacitance on power loses associated with corona discharge

The determining factor for the presence of a corona is the value of the charge of the wire, which determines the intensity of the electric field. Quantitative characteristics of the charge value of the line phase depend on the capacity and voltage. If the influence of voltage on corona losses has been studied by many authors, the influence of capacity is practically not studied. This is primarily due to the fact that the constructive implementation of the split phase of the overhead line was very carefully determined by regulatory documents. In our opinion, today there are all possibilities for changing the designs of phases and, accordingly, their capacities. This became possible thanks to a change in approaches to the design of the structure of the phase wire on the substation. Determination of the electric capacity of the overhead line with bundled conductors is quite often performed using equivalent parameters, such as equivalent suspension height and equivalent radius. This approach makes it possible to obtain average values of the phase capacity of the overhead line. For a detailed analysis of the effect of capacity on corona losses, it is necessary to determine more reliable values of capacities and use them in calculations of corona losses. The capacity of the phase is determined by the geometric dimensions of the split phase. The obtained results indicate a very strong dependence of corona losses on the capacity of the split phase. When approaching a grounded object, the phase capacity can significantly increase. A vivid example of such an increase is the approach of bundled conductors to the elements of overhead line supports. The distances to the ground in this case will be smaller than the equivalent height of the suspension, which is used in the calculations of the specific losses per crown to determine the capacity of the phases of the overhead line. It is necessary to take into account possible changes in the capacity of the split phase at the stage of designing the overhead line. Another result of the calculations was a much greater influence of the capacity of the middle phase on the amount of losses per corona. This makes it possible to reduce corona losses due to the appropriate design of the middle phase of the overhead line, for example, by changing its splitting radius.

When might we break the rules? A statistical analysis of aesthetics in photographs.

High-quality photographs often follow certain high-level rules well known to photographers, but some photographs intentionally break these rules. Doing so is usually a matter of artistry and intuition, and the conditions and patterns that allow for rule-breaks are often not well articulated by photographers. This article first applies statistical techniques to help find and evaluate rule-breaking photographs, and then from these photographs discover those patterns that justify their rule-breaking. With this approach, this article discovered some significant patterns that explain why some high-quality photographs successfully break the common photographic rules by positioning the subject in the center or the horizon in the vertical center. These patterns included reflections, leading lines, crossing objects, ambiguous lines, implied lines, thirds line subjects, and busy foregrounds for center horizon photographs, and symmetry, circular-shaped objects, thirds line elements, gestalt, framing, leading lines, and perspective lines for center subject photographs.

Anisotropic spacetimes in f(T, B) theory II: Kantowski–Sachs Universe

In the context of the modified teleparallel f(T, B) theory of gravity, we consider a homogeneous and anisotropic background geometry described by the Kantowski–Sachs line element. We derive the field equations and investigate the existence of exact solutions. Furthermore, the evolution of the trajectories for the field equations is studied by deriving the stationary points at the finite and infinite regimes. For the $$f(T,B)=T+F\left( B\right) $$ theory, we prove that for a specific limit of the function $$F\left( B\right) $$ , the anisotropic Universe has the expanding and isotropic Universe as an attractor with zero spatial curvature. We remark that there are no future attractors where the asymptotic solution describes a Universe with nonzero spatial curvature.

Orbit Propagation and Lifetime Analysis of NARSSCUBE-2 Using High Precision Numerical Approach

Due to their short mission lifetime, Cube satellites launched in the last decades have increased the number of objects in Low Earth Orbits and the number of space debris. As a result, it is important to obtain accurate measurements of CubeSats trajectories in order to determine their decay and orbital lifetime and to avoid collisions with debris. In this paper, a special perturbation technique has been used as an orbit propagator in order to model orbital motion and predict the behavior of Cube satellites subjected to perturbations. This technique is a high-precision numerical approach via Cowell's formulation with adaptive step size Runge-Kutta-Fehlberg (RKF78) for numerical integration. The technique used is named SPC (Special Perturbation using Cowell's method). Orbit propagation and orbital decay evolution of NARSSCUBE-2 have been analyzed using appropriate orbital parameters derived from historic NORAD Two Line Element sets. The results from the SPC technique have been compared with the SGP4 analytical orbit propagator and then verified with the HPOP numerical orbit propagator from FreeFlyer® astrodynamics software. The accuracy of each propagator has been verified with the observation data. The SPC orbit propagator gives a higher accuracy of orbit prediction compared to SGP4 and closely matches with HPOP.

Covariant Space-Time Line Elements in the Friedmann–Lemaitre–Robertson–Walker Geometry

Most quantum gravity theories quantize space-time on the order of Planck length (ℓp ). Some of these theories, such as loop quantum gravity (LQG), predict that this discreetness could be manifested through Lorentz invariance violations (LIV) over travelling particles at astronomical length distances. However, reports on LIV are controversial, and space discreetness could still be compatible with Lorentz invariance. Here, it is tested whether space quantization on the order of Planck length could still be compatible with Lorentz invariance through the application of a covariant geometric uncertainty principle (GeUP) as a constraint over geodesics in FRW geometries. Space-time line elements compatible with the uncertainty principle are calculated for a homogeneous, isotropic expanding Universe represented by the Friedmann–Lemaitre–Robertson–Walker solution to General Relativity (FLRW or FRW metric). A generic expression for the quadratic proper space-time line element is derived, proportional to Planck length-squared, and dependent on two contributions. The first is associated to the energy–time uncertainty, and the second depends on the Hubble function. The results are in agreement with space-time quantization on the expected length orders, according to quantum gravity theories, and within experimental constraints on putative LIV.

An Autonomous Storage Optimization LRM Generation Strategy Based on Cascaded NURBS

Automatic control of intelligent vehicles depends heavily on accurate lane-level location information. The traditional digital map cannot meet the automatic driving requirements, and it is very difficult for lane-level road maps (LRMs) to achieve a good balance between the representation accuracy and data storage volume. To tackle this problem, we obtain the recursive definition of a lane line by analyzing road lanes using the fractal geometry theory. Subsequently, we construct a recursive feedback system and model it. On this basis, an autonomous storage optimization LRM generation strategy based on cascaded NURBS is devised. According to the input data density, this framework generates an LRM with the minimum data storage volume within the error constraint. It is mainly composed of two modules: (1) a random fractal and (2) an adaptive iteration memory optimizer, based on cascaded NURBS error feedback. First, the whole lane is divided into several meta lane line modules. Second, data sampling/interpolation is carried out iteratively according to the NURBS fitting error and symmetry of road geometry. In this way, the storage space used to store lane lines and other information is automatically optimized. Last, a simulation experiment is carried out by using a dataset obtained from a park. The simulation results show that the proposed method can achieve high accuracy and high storage efficiency. Under the constraint of a 0.1 m curve fitting error, the average memory demand of the lane line elements is less than 2.4 bytes/m.

ABOUT REQUIREMENTS TO PLUGGING MATERIALS AND TO TUBING TECHNOLOGY FOR THE CASING COLUMNS WORKING IN EXTREME CONDITIONS

The most vulnerable elements of the well lining is cement paste in injection wells and the lower parts of the intermediate and surface casings, which suggests the need for the study of additional requirements to plugging materials and lining technology of the specified lining elements. Analysis shows that the main number of workover happens for the share of injection wells, and the number of detected violations in injection wells which is more than an order of magnitude exceeds the corresponding figures for the production casing. Samples of cement stone, selected from the injection and production wells showed that in injection wells, the cement stone collapses in 4-5 years.The mechanism and kinetic process of destruction of cement stone under the influence of leaching was considered and the ways of increasing the durability of linings in injection wells were shown. Leaching corrosion processes in injection wells strengthens during the formation of cracks in the cement stone as a result of technological operation inside the casing string. The most dangerous technological operations are; perforation and deepening of the well. In order to obtain high-quality well anchoring, it is inevitable to regulate the basic properties of cement mortars with the help of various chemical reagents. At the same time, the filtration characteristics (water output and water separation), setting time, pumpability, rheological parameters, as well as the properties of the resulting stone require correction most often in grouting solutions It is shown that for plugging materials, the most preferred way to increase the resistance of grouting stone to dynamic loads is dispersed reinforcement, which can be effectively regulated by the most important characteristics of cement slurries and cement stone can be obtained from them. Studies have been conducted on the influence of basalt fiber and polyamide fiber on the basic physical and mechanical properties of the resulting stone, such as the strength of cement stone, deformation of cement stone during destruction, the specific impact strength of Portland cement stone, as well as the permeability of cement stone. Studies have shown positive results of the addition of basalt fiber at concentrations up to 2%.

Comparison between computational cost of fractals using line-doublets

In this work, we study the two-dimensional groundwater flow of fractured porous media with the help of analytic element method. A numerical solution formed by line elements called line-doublets based on a series expansion has been presented in the literature. In this solution, each fracture has an influence that may expand in a series that obeys Laplace’s equation exactly. The unknown coefficients are found from the discharge potentials of all other elements that are related to the expansion coefficients in series expansion. This work aims to make comparison between the computational cost for fractals by the analytic element method with different techniques like: Iterative and Matrix method.

Determining Out-of-Field Doses and Second Cancer Risk From Proton Therapy in Young Patients-An Overview.

Proton therapy has the potential to provide survival and tumor control outcomes comparable and frequently superior to photon therapy. This has led to a significant concern in the medical physics community on the risk for the induction of second cancers in all patients and especially in younger patients, as they are considered more radiosensitive than adults and have an even longer expected lifetime after treatment. Thus, our purpose is to present an overview of the research carried out on the evaluation of out-of-field doses linked to second cancer induction and the prediction of this risk. Most investigations consisted of Monte Carlo simulations in passive beam facilities for clinical scenarios. These works established that equivalent doses in organs could be up to 200 mSv or 900 mSv for a brain or a craniospinal treatment, respectively. The major contribution to this dose comes from the secondary neutrons produced in the beam line elements. Few works focused on scanned-beam facilities, but available data show that, for these facilities, equivalent doses could be between 2 and 50 times lower. Patient age is a relevant factor in the dose level, especially for younger patients (by means of the size of the body) and, in addition, in the predicted risk by models (due to the age dependence of the radiosensitivity). For risks, the sex of the patient also plays an important role, as female patients show higher sensitivity to radiation. Thus, predicted risks of craniospinal irradiation can range from 8% for a 15-year-old male patient to 58% for a 2-year-old female patient, using a risk model from a radiological protection field. These values must be taken with caution due to uncertainties in risk models, and then dosimetric evaluation of stray radiation becomes mandatory in order to complement epidemiological studies and be able to model appropriate dose–response functions for this dose range. In this sense, analytical models represent a useful tool and some models have been implemented to be used for young patients. Research carried out so far confirmed that proton beam therapy reduces the out-of-field doses and second cancer risk. However, further investigations may be required in scanned-beam delivery systems.

Ethical Treatment of Invasive and Native Fauna in Australia: Perspectives through the One Welfare Lens.

Simple SummaryA public forum can reveal a wide range of perspectives on the ethical treatment of animals. This article describes how a panel of experts navigated through a discussion on the many and varied challenges of attempting to manage invasive and native fauna in Australia. The panel acknowledged the variety of these fauna, their effects on others and the consequences of control measures for three parties: animals, humans and the environment. The One Welfare concept has been developed to guide humans in the ethical treatment of non-human animals, each other and the environment. The forum accepted the need to consider this triple line, and exemplifies the merits of a One Welfare approach to discussions such as this. We used a series of questions about past, present and anticipated practices in wildlife control as the core of the panel discussion. We revealed five different but intersecting perspectives: conservation action, wildlife research, invasive animal ecology, mainstream animal protection and compassionate conservation. This article shows how understanding of lines of contention on various core topics can provide a framework for further discourse that may bear fruit in the form of One Welfare solutions.The One Welfare concept is proposed to guide humans in the ethical treatment of non-human animals, each other and the environment. One Welfare was conceptualized for veterinarians but could be a foundational concept through which to promote the ethical treatment of animals that are outside of direct human care and responsibility. However, wild-living animals raise additional ethical conundrums because of their multifarious values and roles, and relationships that humans have with them. At an open facilitated forum, the 2018 Robert Dixon Memorial Animal Welfare Symposium, a panel of five experts from different fields shared their perspectives on “loving and hating animals in the wild” and responded to unscripted questions from the audience. The Symposium’s objectives were to elucidate views on the ethical treatment of the native and invasive animals of Australia and to identify some of the resultant dilemmas facing conservationists, educators, veterinarians and society. Here, we document the presented views and case studies and synthesize common themes in a One Welfare framework. Additionally, we identified points of contention that can guide further discourse. With this guide in place, the identification and discussion of those disparate views was a first step toward practical resolutions on how to manage wild-living Australian fauna ethically. We concluded that there was great utility in the One Welfare approach for any discourse about wild animal welfare. It requires attention to each element of the triple bottom line and ensures that advocacy for one party does not vanquish the voices from other sectors. We argue that, by facilitating a focus on the ecology in the context of wild animal issues, One Welfare is more useful in this context than the veterinary context for which it was originally developed.

METHODS FOR MITIGATION OF MAGNETIC FIELD GENERATED BY UNDERGROUND POWER CABLES IN POLYETHYLENE PIPES MADE OF COMPOSITE MAGNETIC MATERIAL

The magnetic field of a high-voltage (330 kV) underground single-circuit power cable line, laid in a polyethylene pipe having magnetic properties, with the use of special loose-fill/fill-up soil of different dimensions (bulk) is studied by computer modeling. The pipe and additional soil around and near the cables are made of a composite material with effective magnetic properties and can act as a magnetic shield that reduces the level of the field on the ground. The efficiency of field shielding depending on the height and width of the composite loose-fill/fill-up soil is analyzed. The existence of the optimal not large (in height) fill-up soil for the best mitigation of the magnetic field on the ground directly above the cables, and the influence of the width of the loose-fill/fill-up soils on the shielding efficiency are revealed. The characteristic features of the magnetic field distribution within the considered shielding elements of the cable line depending on the availability or non-availability of composite loose-fill soil and the height of the fill-up soil with effective magnetic properties are presented. The shielding efficiency of underground single-circuit three-phase power cable lines when using the magnetic fill-up soil with a certain small height (volume) is grounded. References 11, figures 4.

Displacement discontinuity method for interfacial cracks in one-dimensional hexagonal quasi-crystal coating under thermal-mechanical loading

This study derived Green’s functions of the concentrated interfacial displacement and temperature discontinuities. Green’s functions and the displacement and temperature discontinuity method were used to analyze interfacial cracks in a one-dimensional (1D) hexagonal quasi-crystal (QC) coating under thermal-mechanical loading. The boundary integral-differential equations were established for an interfacial crack, the fundamental solutions were obtained for uniformly distributed temperature, and the displacement discontinuities were applied over a line element. The near-crack-tip oscillatory singularity of stresses was eliminated by introducing the Gaussian distribution function to approximate the delta function. After this treatment, the expressions of the stress and heat flux intensity factors without oscillatory singularity, and the energy release rate (ERR) at the crack tips were obtained. The displacement and temperature discontinuity boundary element method for numerical simulation is proposed, and the influence of relevant factors is briefly discussed.

About the Cover

At the iSchool, we study information. What information was traditionally perceived as is changing. Thus, our program has evolved to encompass the many domains information has branched into with its various concentrations. The changes should not come as a surprise, as information is all around us. The flowing design elements of the cover allude to the emerging connections and intersections of information between individuals and between other disciplines. The colour scheme is inspired by the colours of the Claude T. Bissell building at the University of Toronto, also home to the iSchool. The building was built in 1971 as part of Robarts Library—an iconic piece of Brutalist architecture in North America. The font used was Times New Roman. It is a classic font which alludes to our roots, contrasting with the curving line elements, which allude to the different directions the study of information can take us.