Direction Of Vector Research Articles

Arthropods as Vectors of Grapevine Trunk Disease Pathogens: Quantification of Phaeomoniella chlamydospora on Arthropods and Mycobiome Analysis of Earwig Exoskeletons.

Viticulture worldwide is challenged by grapevine trunk diseases (GTDs). Involvement of arthropods in the dissemination process of GTD pathogens, notably esca pathogens, is indicated after detection of associated pathogens on arthropod exoskeletons, and demonstration of transmission under artificial conditions. The present study is the first to quantify spore loads via qPCR of the esca-relevant pathogen Phaeomoniella chlamydospora on arthropods collected in German vineyards, i.e., European earwigs (Forficula auricularia), ants (Formicidae), and two species of jumping spiders (Marpissa muscosa and Synageles venator). Quantification of spore loads showed acquisition on exoskeletons, but most arthropods carried only low amounts. The mycobiome on earwig exoskeletons was described for the first time to reveal involvement of earwigs in the dispersal of GTDs in general. Metabarcoding data support the potential risk of earwigs as vectors for predominantly Pa. chlamydospora and possibly Eutypa lata (causative agent of Eutypa dieback), as respective operational taxonomical unit (OTU) assigned genera had relative abundances of 6.6% and 2.8% in total reads, even though with great variation between samples. Seven further GTD-related genera were present at a very low level. As various factors influence the successful transmission of GTD pathogens, we hypothesize that arthropods might irregularly act as direct vectors. Our results highlight the importance of minimizing and protecting pruning wounds in the field.

Comments on Parallel Curves in 3-Dimensional Lie Group G

In this study, firstly, basic concepts in 3-dimensional Euclidean space and basic information about curves are given and some special curves are examined. Then, basic information about Lie algebra and Lie group basic concepts and curves are given and special curves such as helix, involute-evolute, Bertrand, Mannheim, Smarandache, are defined. Secondly, inspired by these special curves examined in the Lie group, the definitions of the parallel curve in the vector direction, the parallel curve in the direction of the vector B and the parallel curve in the direction of the linear combination of the vectors B and N of a curve according to the Frenet frame are given and characterized. Some theorems and results are obtained by finding the Frenet apparatus of these characterized curves. Finally, the findings are examined in more specific circumstances and new results are found.

Autonomous navigation method of satellite constellation based on adaptive forgetting factors

To address the problem that model uncertainty and unknown time-varying system noise hinder the filtering accuracy of the autonomous navigation system of satellite constellation, an autonomous navigation method of satellite constellation based on the Unscented Kalman Filter with Adaptive Forgetting Factors (UKF-AFF) is proposed. The process noise covariance matrix is estimated online with the strategy that combines covariance matching and adaptive adjustment of forgetting factors. The adaptive adjustment coefficient based on squared Mahalanobis distance of state residual is employed to achieve online regulation of forgetting factors, equipping this method with more adaptability. The intersatellite direction vector obtained from photographic observations is introduced to determine the constellation satellite orbit together with the distance measurement to avoid rank deficiency issues. Considering that the number of available measurements varies online with intersatellite visibility in practical applications such as time-varying constellation configurations, the smooth covariance matrix of state correction determined by innovation and gain is adopted and constructed recursively. Stability analysis of the proposed method is also conducted. The effectiveness of the proposed method is verified by the Monte Carlo simulation and comparison experiments. The estimation accuracy of constellation position and velocity of UKF-AFF is improved by 30% and 44% respectively compared to those of the extended Kalman filter, and the method proposed is also better than other several adaptive filtering methods in the presence of significant model uncertainty.

Magnetic soliton and breather interactions for the higher-order Heisenberg ferromagnetic equation via the iterative N-fold Darboux transformation

This paper focuses on a higher-order Heisenberg ferromagnetic equation, which may describe the motion of the magnetic vector of isotropic ferromagnetism. The iterative N-fold Darboux transformation is first constructed to generate the dark and anti-dark magnetic solitons on the non-zero constant backgrounds, bright and dark breathers on the trigonometric function and non-zero constant backgrounds as well as breathers on the trigonometric function and vanishing backgrounds. We discover that the soliton structures of three different components can generate rotation with different constant seed solutions. Meanwhile, the trajectory curve and the direction of the magnetic vector are also discussed from the perspective of magnetism, we find that for constant seed solutions, the motion of the magnetic vector is limited to the hemisphere, while for trigonometric seed solutions, the motion of the magnetic vector can be distributed throughout the whole sphere. These novel phenomena may be helpful to understand the dynamics of the magnetic vector in the magnetic materials.

Indicating the direction in conservation of angular momentum

This study developed a teaching material that makes the conservation of angular momentum, which students find very difficult, more concrete. The fact that angular momentum is a vector concept, the direction of the vector and the importance of this vector direction in angular momentum conservation are visualized. The teaching material consists of a table mounted on a freely rotating shaft, two electric motors mutually connected to the table, and a speed adjuster circuit used to change the rotation speeds of the motors. When electric motors begin to rotate, the angular momentum of the motors changes. How the angular momentum of the system is preserved thanks to the changing angular momentum of the parts interacting with each other, the directions of the vectors formed, the inertia torque, angular velocity, angular momentum relationship, and the relationship of the parts forming a system with each other have been tried to be explained in detail through the teaching material. When the motors were operated in different directions and speeds, the change in the rotation direction of the table was observed. This observation concretizes that angular momentum and angular momentum conservation are vector concepts. The right-hand rule, which describes the angular momentum vector direction with the material, can be demonstrated to students in practice. Video recordings showing how the teaching material works have been shared with readers.

Collision-free path planning for cable-driven continuum robot based on improved artificial potential field

AbstractContinuum robot has become a research hotspot due to its excellent dexterity, flexibility and applicability to constrained environments. However, the effective, secure and accurate path planning for the continuum robot remains a challenging issue, for that it is difficult to choose a suitable inverse kinematics solution due to its redundancy in the confined environment. This paper presents a collision-free path planning method based on the improved artificial potential field (APF) for the cable-driven continuum robot, in which the beetle antennae search algorithm is adopted to deal with the optimal problem of APF without the necessary for velocity kinematics. In addition, the local optimum problem of traditional APF is solved by the randomness of the antennae’s direction vector which can make the algorithm easily jump out of local minima. The simulation and experimental results verify the efficiency of the proposed path planning method.

Performance Evaluation of Square Cyclone Separator with Cone Geometry Variations

Rapid industrial development with intensive operations increases exhaust emissions that are polluting the environment and human health. Efforts to overcome the problem are urgent to be realized, one of which is by using a particle separator such as a cyclone separator. Along with that, the design of a cyclone separator with the best performance is very important. Therefore, it is necessary to innovate and analyze the design of the cyclone separator by varying the cone geometry of the cyclone. This study aimed to determine the best square cyclone separator among square cyclone separators with various cone geometries, including single cone, dual inverse cone 1, and dual inverse cone 2. It was conducted by Computational Fluid Dynamics (CFD) simulation and experiments and then continued by comparing pre-determined aspects comprising pressure drop, collection efficiency, static pressure contours, tangential velocity contours in the cyclone body, tangential velocity vectors in the cone geometry, and tangential velocity vectors at the cyclone inlet. The single cone is the best among all cone variations since it fulfils more aspects better than the dual inverse cones, namely: dominantly lowest pressure drop of 188.5 Pa, static pressure contour of 10.42 Pa, tangential velocity contour of 3.06 m/s, flow direction of the tangential velocity vector in the cyclone geometry was at the centre of the bin, and flow direction of the tangential velocity vector at the cyclone inlet was parallel.

Plant capacity utilization with piecewise Cobb-Douglas technology: Definition and interpretation

Convex and nonconvex nonparametric technologies have been applied to estimate plant capacity utilization. However, they face challenges in capturing the production characteristic that involves the simultaneous consideration of increasing, constant, and decreasing marginal production rates along the production surfaces, which may be inconsistent with the standard microeconomic production theory. This inconsistency raises concerns regarding the potential bias of plant capacity utilization estimates. Thus, this paper introduces a new plant capacity utilization measure based on the piecewise Cobb–Douglas technology, aligned with the standard microeconomic production theory. This measure is defined using two multiplicative directional distance functions with optimal endogenous directions. It can be interpreted by the Euclidean distance between two points associated with optimal capacities and the Euclidean norm of one optimal endogenous direction vector. The new measure captures potential production slacks to measure plant capacity in the sense of Pareto–Koopmans efficiency. It also suggests a remedy of non-existence of a maximal plant capacity in the Cobb–Douglas function by utilizing the piecewise Cobb–Douglas technology. The proposed plant capacity utilization measure is validated using a secondary dataset of 19 Chilean hydroelectric power plants.

Leveraging Biotic Interaction Knowledge Graph and Network Analysis to Uncover Insect Vectors of Plant Virus

Background: Insect vectors spread 80% of plant viruses, causing major agricultural production losses. Direct insect vector identification is difficult due to a wide range of hosts, limited detection methods, and high PCR costs and expertise. Currently, a biodiversity database named Global Biotic Interaction (GloBI) provides an opportunity to identify virus vectors using its data. Objective: This study aims to build an insect vector search engine that can construct an virus-insect-plant interaction knowledge graph, identify insect vectors using network analysis, and extend knowledge about identified insect vectors. Methods: We leverage GloBI data to construct a graph that shows the complex relationships between insects, viruses, and plants. We identify insect vectors using interaction analysis and taxonomy analysis, then combine them into a final score. In interaction analysis, we propose Targeted Node Centric-Degree Centrality (TNC-DC) which finds insects with many directly and indirectly connections to the virus. Finally, we integrate Wikidata, DBPedia, and NCBIOntology to provide comprehensive information about insect vectors in the knowledge extension stage. Results: The interaction graph for each test virus was created. At the test stage, interaction and taxonomic analysis achieved 0.80 precision. TNC-DC succeeded in overcoming the failure of the original degree centrality which always got bees in the prediction results. During knowledge extension stage, we succeeded in finding the natural enemy of the Bemisia Tabaci (an insect vector of Pepper Yellow Leaf Curl Virus). Furthermore, an insect vector search engine is developed. The search engine provides network analysis insights, insect vector common names, photos, descriptions, natural enemies, other species, and relevant publications about the predicted insect vector. Conclusion: An insect vector search engine correctly identified virus vectors using GloBI data, TNC-DC, and entity embedding. Average precision was 0.80 in precision tests. There is a note that some insects are best in the first-to-five order. Keywords: Knowledge Graph, Network Analysis, Degree Centrality, Entity Embedding, Insect Vector

Visual–Inertial Odometry of Structured and Unstructured Lines Based on Vanishing Points in Indoor Environments

In conventional point-line visual–inertial odometry systems in indoor environments, consideration of spatial position recovery and line feature classification can improve localization accuracy. In this paper, a monocular visual–inertial odometry based on structured and unstructured line features of vanishing points is proposed. First, the degeneracy phenomenon caused by a special geometric relationship between epipoles and line features is analyzed in the process of triangulation, and a degeneracy detection strategy is designed to determine the location of the epipoles. Then, considering that the vanishing point and the epipole coincide at infinity, the vanishing point feature is introduced to solve the degeneracy and direction vector optimization problem of line features. Finally, threshold constraints are used to categorize straight lines into structural and non-structural features under the Manhattan world assumption, and the vanishing point measurement model is added to the sliding window for joint optimization. Comparative tests on the EuRoC and TUM-VI public datasets validated the effectiveness of the proposed method.

Dyakonov surface polaritons in bi-hyperbolic metamaterial

A periodically layered metamaterial (MM) structured with antiferromagnetic (AF) and ionic-crystal (IC) layers was proposed, which exhibits bi-hyperbolicity with effective hyperbolic permeability and permittivity. We investigated Dyakonov surface polaritons (DSPs) localized at this bi-hyperbolic metamaterial surface. For such a complicated material system, we analytically acquired one concise dispersion equation and corresponding wave solutions. From them, we found four DSPs, or DSP-I, DSP-II, DSP-III, and DSP-IV, and meanwhile one Dyakonov surface magnon and one Dyakonov surface phonon were found in this bi-hyperbolic metamaterial. The ATR spectra numerically calculated clearly proved the actual existence of the DSPs acquired from the dispersion equation and offered the path to excite and observe the DSPs. The DSP’s energy propagating direction is parallel to the air/MM interface, but not along the wave vector direction, and further it can approximatively be vertical to the wave-vector.

The Hunt for Perpendicular Magnetic Field Measurements in Plasma

The one consistent technique for remotely estimating the magnetic field in plasma has been Faraday rotation. It is only sensitive to the portion of the vector parallel to the propagation path. We show how to remotely detect the portion of the vector that is perpendicular using a modified measurement. Isolating this electromagnetic propagation wave mode to measure the magnetic field enables us to (i) study more about the magnetic field vector in plasma, (ii) reduce error in total electron content measurements, and (iii) discover new magnetic field information from archived data sets. The Appleton–Hartree equation is used to verify a new approach to calculating the phase change to an electromagnetic wave propagating through a plasma at frequencies larger than the gyrofrequency, the cyclotron frequency, and the upper hybrid frequency. Focusing on the perpendicular propagation modes, the simplified equation for the integrated path effect from a perpendicular magnetic field is calculated. The direction of the perpendicular component is unknown, because the magnetic field is squared. Isolating the magnetic term in the equation with dual frequency waves is shown. We also show how to eliminate the magnetic field contribution to total electron content measurements with a similar approach. In combination with Faraday rotation, the degeneracy of the magnetic field vector direction is reduced to a cone configuration.

A spectral finite element Reissner–Mindlin shell formulation with NURBS-based geometry definition

A curved non-isoparametric Reissner–Mindlin shell element is developed for analyzing thin-walled structures. The standard kinematic description of the element requires the calculation of the director vector. To address this demand accurately, similar to isogeometric analysis (IGA), the geometry is defined by utilization of the non-uniform rational B-splines (NURBS) imported directly from computer-aided design (CAD) files. Then, shape functions of the Legendre spectral element method (SEM) are used to interpolate the displacements. Consequently, the shell director vector and Jacobian of the transformation are calculated properly according to the presented formulation. On the other hand, in Legendre SEM combined with Gauss–Lobatto–Legendre quadrature, the integration points and the element nodes coincide. Thus, the easily computable local coordinate systems at the integration points can be used directly as nodal basis systems. A separate calculation of nodal basis systems at control points, which is the source of either complexity or error in IGA shells, is not required. Given the condition number of the stiffness matrix in the developed method, super high-order elements can also be used. Very high order p-refined elements are used in addition to h-refinement of the mesh to show the capability of higher order elements to analyze problems without mesh refinement. The validity and convergence rate of the method are investigated and verified through various cases of h- and p-refinement in challenging obstacle course problems.

Можливості підвищення безпеки руху рейкових екіпажів з колесами, що незалежно обертаються

One of the promising ways to achieve high speed and smooth running of rail vehicles during stable movement in straight sections of the track and to improve the characteristics of fitting the vehicles in a curve is the use of independently rotating wheels in their running parts. Such undercarriages are already becoming quite widespread, for example, in urban rail transport vehicles. But independently rotating wheels can rotate in a wheel pair around a common axis with different angular velocities. It follows that during their movement, longitudinal creep forces do not arise, which form the controlling moment and center the wheel pair in the rail track. This can lead to increased angles of attack of the wheels on the rails, increased lateral forces and accelerated wear of the wheels and rails. In turn, this increases the tendency of vehicles with independently rotating wheels to derail by rolling the flange onto the head of the rail. 
 The accumulated global experience of operating similar vehicles confirms this. To overcome the mentioned disadvantages of independently rotating wheels, a number of various technical solutions have been proposed. Some of them relate to ensuring the given elastic-dissipative characteristic of the torsional articulation of the wheels in a wheel pair. A promising direction is the improvement of the characteristics of the connections of wheel pairs with the bogye and bogyes with the vehicle body, the use of mechatronic systems for controlling the position of the wheel pairs in the horizontal plane for their radial installation in curved sections of the track. In this work, attention is paid to the issue of the use in the design of independently rotating wheels of a perspective design scheme that allows independent rotation of the wheel's support surface and its guide surface (flange). The question of the effect of changing the design scheme of the wheel on the safety of movement due to the roll-in of the ridge on the rail head was considered. 
 The influence of a promising design scheme of a wheel in comparison with a traditional design scheme of a wheel on the safety of driving down a rails was investigated. The peculiarities of the distribution of frictional forces in the ridge contact during movement along the rails of the wheels of both design schemes are analyzed. For a wheel of a traditional design scheme, the module and the direction of the friction force vector in the ridge contact are uniquely determined by the geometric characteristics of the contact between the wheel and the rail and the angular speed of the wheel rotation. At the same time, when the wheel of the prospective design scheme moves, the direction and module of the friction force vector of the ridge on the rail also depend on the ratio of the angular velocities of rotation of the supporting surface of the wheel and its guiding surface (flange) around the common axis. The obtained results allow us to draw a conclusion about the expediency of using a promising design scheme in independently rotating wheels to increase the safety of movement of rail vehicles.

SAR Multi-Angle Observation Method for Multipath Suppression in Enclosed Spaces

Synthetic aperture radar (SAR) is a powerful tool for detecting and imaging targets in enclosed environments, such as tunnels and underground garages. However, SAR performance is degraded by multipath effects, which occur when electromagnetic waves are reflected by obstacles, such as walls, and interfere with the direct signal. This results in the formation of multipath ghost images, which obscure the true target and reduce the image quality. To overcome this challenge, we propose a novel method based on multi-angle observation. This method exploits the fact that the position of ghost images changes depending on the angle of the radar, while the position of the true target remains stable. By collecting and processing multiple data sets from different angles, we can eliminate the ghost images and enhance the target image. In addition, we introduce a center vector distance algorithm to address the complexity and computational intensity of existing multipath suppression algorithms. This algorithm, which defines the primary direction of multi-angle vectors from stable scattering centers as the center vector, processes and synthesizes multiple data sets from multi-angle observations. It calculates the distance of pixel intensity sequences in the composite data image from the center vector. Pixels within a specified threshold are used for imaging, and the final result is obtained. Simulation experiments and real SAR data from underground garages confirm the effectiveness of this method in suppressing multipath ghost images.

Transforming a head direction signal into a goal-oriented steering command.

To navigate, we must continuously estimate the direction we are headed in, and we must correct deviations from our goal1. Direction estimation is accomplished by ring attractor networks in the head direction system2,3. However, we do not fully understand how the sense of direction is used to guide action. Drosophila connectome analyses4,5 reveal three cell populations (PFL3R, PFL3L and PFL2) that connect the head direction system to the locomotor system. Here we use imaging, electrophysiology and chemogenetic stimulation during navigation to show how these populations function. Each population receives a shifted copy of the head direction vector, such that their three reference frames are shifted approximately 120° relative to each other. Each cell type then compares its own head direction vector with a common goal vector; specifically, it evaluates the congruence of these vectors via a nonlinear transformation. The output of all three cell populations is then combined to generate locomotor commands. PFL3R cells are recruited when the fly is oriented to the left of its goal, and their activity drives rightward turning; the reverse is true for PFL3L. Meanwhile, PFL2 cells increase steering speed, and are recruited when the fly is oriented far from its goal. PFL2 cells adaptively increase the strength of steering as directional error increases, effectively managing the tradeoff between speed and accuracy. Together, our results show how a map of space in the brain can be combined with an internal goal to generate action commands, via a transformation from world-centric coordinates to body-centric coordinates.

A general parametric finite element modeling and stress response analysis methods for pipeline system using the nonconforming solid element

In the dynamic topology optimization design of pipeline system, parametric finite element modeling (PFEM) is needed to improve the model reconstruction efficiency. Taking a typical spatial single pipeline as the research object, this paper innovatively presents a PFEM method of pipeline system based on the newly constructed nonconforming solid (Solid-NC) element. The stiffness and mass matrices of the spatial 8-node Solid-NC element with second-order boundary accuracy are obtained by introducing the node-free displacement items and statics condensation method. The PFEM method of the pipeline body is proposed by selecting the straight-line segment lengths as the pipeline shape control parameters. The PFEM method of the pipeline is described in detail, including the node coordinate solutions of straight-line and curved arc segments based on the direction vector method and vector decomposition method, respectively, and the simulation of the clamp mechanical properties considering the actual pre-tightening state of the clamp. Furthermore, the modal analysis is carried out, the node stress response solution is solved based on the stress smoothing method, and the effectiveness of the PFEM method is verified through experiment. Finally, the mesh quality and model reconstruction efficiency of the PFEM method is analyzed, the results show that the developed PFEM method has higher mesh quality and fast model reconstruction speed, and the model reconstruction time is shortened by 544.5 times at most compared with ANSYS software.

Directional vector visualization of scattered rays in mobile c-arm fluoroscopy.

Previous radiation protection-measure studies for medical staff who perform X-ray fluoroscopy have employed simulations to investigate the use of protective plates and their shielding effectiveness. Incorporating directional information enables users to gain a clearer understanding of how to position protective plates effectively. Therefore, in this study, we propose the visualization of the directional vectors of scattered rays. X-ray fluoroscopy was performed; the particle and heavy-ion transport code system was used in Monte Carlo simulations to reproduce the behavior of scattered rays in an X-ray room by reproducing a C-arm X-ray fluoroscopy system. Using the calculated results of the scattered-ray behavior, the vectors of photons scattered from the phantom were visualized in three dimensions. A model of the physician was placed on the directional vectors and dose distribution maps to confirm the direction of the scattered rays toward the physician when the protective plate was in place. Simulation accuracy was confirmed by measuring the ambient dose equivalent and comparing the measured and calculated values (agreed within 10%). The directional vectors of the scattered rays radiated outward from the phantom, confirming a large amount of backscatter radiation. The use of a protective plate between the patient and the physician's head part increased the shielding effect, thereby enhancing radiation protection for the physicians compared to cases without the protective plate. The use of directional vectors and the surrounding dose-equivalent distribution of this method can elucidate the appropriate use of radiation protection plates.

Focusing of linearly polarized optical vortex and a Hall effect

Polarization of a higher-order cylindrical vector beam (CVB) is known to be locally linear. The higher the beam order, the larger number of full circles the local linear polarization vector makes around the optical axis. It is also known that the CVB with radially symmetric amplitude has zero spin angular momentum (SAM) and zero orbital angular momentum (OAM) both in the initial plane and in the focal plane (because in both Cartesian components of the vector field, the angular derivative of phase is zero). We show here that near the focal plane of the CVB (i.e. before and beyond the focus), an even number of local subwavelength areas with rotating polarization vectors are generated. In addition, in the neighboring areas, the polarization vectors are rotating in the opposite directions. Thus, the longitudinal components of the SAM vector in such neighboring areas are of different sign. After passing through the focal plane, the rotation direction of the polarization vector at each point of the beam cross-section changes to the opposite one. Such a spatial separation of the left and right rotation of the polarization vectors is a manifestation of the optical spin Hall effect.

Focusing a cylindrical vector beam and the Hall effect

Polarization of a higher-order cylindrical vector beam (CVB) is known to be locally linear. The higher the beam order, the larger number of full circles the local linear polarization vector makes around the optical axis. It is also known that the CVB with radially symmetric amplitude has zero spin angular momentum (SAM) and zero orbital angular momentum (OAM) both in the initial plane and in the focal plane (because in both Cartesian components of the vector field, the angular derivative of phase is zero). We show here that near the focal plane of the CVB (i.e. before and beyond the focus), an even number of local subwavelength areas with rotating polarization vectors are generated. In addition, in the neighboring areas, the polarization vectors are rotating in the opposite directions. Thus, the longitudinal components of the SAM vector in such neighboring areas are of different sign. After passing through the focal plane, the rotation direction of the polarization vector at each point of the beam cross-section changes to the opposite one. Such a spatial separation of the left and right rotation of the polarization vectors is a manifestation of the optical spin Hall effect.