Direction Of Vector Research Articles

From kinetic flocking model of Cucker–Smale type to self-organized hydrodynamic model

We investigate the hydrodynamic limit problem for a kinetic flocking model. We develop a GCI-based Hilbert expansion method, and establish rigorously the asymptotic regime from the kinetic Cucker–Smale model with a confining potential in a mesoscopic scale to the macroscopic limit system for self-propelled individuals, which is derived formally by Aceves-Sánchez et al. in 2019. In the traditional kinetic equation with collisions, for example, Boltzmann-type equations, the key properties that connect the kinetic and fluid regimes are: the linearized collision operator (linearized collision operator around the equilibrium), denoted by [Formula: see text], is symmetric, and has a nontrivial null space (its elements are called collision invariants) which include all the fluid information, i.e. the dimension of Ker([Formula: see text]) is equal to the number of fluid variables. Furthermore, the moments of the collision invariants with the kinetic equations give the macroscopic equations. The new feature and difficulty of the corresponding problem considered in this paper is: the linearized operator [Formula: see text] is not symmetric, i.e. [Formula: see text], where [Formula: see text] is the dual of [Formula: see text]. Moreover, the collision invariants lies in Ker([Formula: see text]), which is called generalized collision invariants (GCI). This is fundamentally different with classical Boltzmann-type equations. This is a common feature of many collective motions of self-propelled particles with alignment in living systems, or many active particle system. Another difficulty (also common for active system) is involved by the normalization of the direction vector, which is highly nonlinear. In this paper, using Cucker–Smale model as an example, we develop systematically a GCI-based expansion method, and micro–macro decomposition on the dual space, to justify the limits to the macroscopic system, a non-Euler-type hyperbolic system. We believe our method has wide applications in the collective motions and active particle systems.

Effect of touch on proprioception: non-invasive trigeminal nerve stimulation suggests general arousal rather than tactile-proprioceptive integration.

Proprioceptive error of estimated fingertip position in two-dimensional space is reduced with the addition of tactile stimulation applied at the fingertip. Tactile input does not disrupt the participants' estimation strategy, as the individual error vector maps maintain their overall structure. This relationship suggests integration of proprioception and tactile information improves proprioceptive estimation, which can also be improved with trained mental focus and attention. Task attention and arousal are physiologically regulated by the reticular activating system (RAS), a brainstem circuit including the locus coeruleus (LC). There is direct and indirect evidence that these structures can be modulated by non-invasive trigeminal nerve stimulation (nTNS), providing an opportunity to examine nTNS effect on the integrative relationship of proprioceptive and tactile information. Fifteen right-handed participants performed a simple right-handed proprioceptive estimation task with tactile feedback (touch) and no tactile (hover) feedback. Participants repeated the task after nTNS administration. Stimulation was delivered for 10 min, and stimulation parameters were 3,000 Hz, 50 μs pulse width, with a mean of 7 mA. Error maps across the workspace are generated using polynomial models of the participants' target responses. Error maps did not demonstrate significant vector direction changes between conditions for any participant, indicating that nTNS does not disrupt spatial proprioception estimation strategies. A linear mixed model regression with nTNS epoch, tactile condition, and the interaction as factors demonstrated that nTNS reduced proprioceptive error under the hover condition only. We argue that nTNS does not disrupt spatial proprioceptive error maps but can improve proprioceptive estimation in the absence of tactile feedback. However, we observe no evidence that nTNS enhances tactile-proprioceptive integration as the touch condition does not exhibit significantly reduced error after nTNS.

Distortion of Magnetic Fields Near a Steel Construction. Modeling

Natural variations of the Earth's magnetic field and its man-made distortions are considered. The rules and regulations in force in the Russian Federation for staying and living in places with a distortion of the Earth's magnetic field are analyzed. Existing methods for eliminating distorted magnetic fields inside residential and work premises are considered. Modeling of distortions of the Earth's magnetic field by building materials was carried out and the influence of their location in space on the overall picture of the resulting magnetic field was shown. To modeling the influence of reinforcement of reinforced concrete constructions on the resulting magnetic field, 6 models of the location of reinforcing bars and their groups were used: one reinforcing bar magnetized against the Earth’s magnetic field and along the Earth’s field; 4 reinforcing bars each, magnetized against the Earth’s magnetic field and magnetized in an alternating manner; the simplest model of a residential structure or public building with 36 reinforcing bars magnetized against the Earth’s magnetic field and with 36 magnetized bars in different directions. Near the model of a rod with magnetization along the Earth’s magnetic field, there are hypogeomagnetic fields. Near the models of a reinforcing bar and four reinforcing bars magnetized against the Earth’s magnetic field, there are no hypogeomagnetic zones and changes in the direction of the magnetic field strength vectors, but strong increases in the resulting magnetic field can be observed - 500 times or more. Near models with 4 reinforcing bars magnetized in an alternating manner, there are the most dangerous zero values of magnetic field strength at a distance of 1 m. Inside the model with 36 reinforcing bars there is a hypogeomagnetic field in the very center of the model and a change in the direction of the magnetic field strength vectors. Near the model with 36 magnetized rods in different directions, a more even resulting magnetic field is observed without sharp changes in its direction and absolute value. Methods have been proposed for eliminating magnetic pathogenic zones at the stages of installation and construction of building that have ferromagnetic materials in their design.

The impact of big fund on the operational efficiency of semiconductor companies: Corporate social responsibility as a non-economic output

This study contributes to research on the total factor operational efficiency of the semiconductor company considering corporate social responsibility (CSR) by proposing a novel integer-valued nonparametric frontier method. This method adopts an endogenous directional distance function, which first selects the benchmark and then endogenously determines the directional vector. Avoiding the issue of non-integer slack adjustment increases the convenience of formulating incentive plans and calculating efficiency. We apply this method to the input–output data of 185 listed Chinese semiconductor companies from 2010 to 2022, considering integer-valued CSR as non-economic output. Global Malmquist productivity index analysis shows that the average total factor operational efficiency of companies that received investment from the National Integrated Circuit Industry Investment Fund (Big Fund) increased by 6.9%. Using the econometric technique, we verify that the total factor operational efficiency of semiconductor companies receiving Big Fund investment increased by 0.084 compared to those without Big Fund investment. Heterogeneity analysis showed that the effect of Big Fund was more significant in improving the total factor operational efficiency of state-owned, new, and non-integrated circuit semiconductor companies, implying the necessity of purposeful investment policies for the Big Fund.

МГД-волны в области предфронта межпланетных ударных волн 6 и 7 сентября 2017 г.

We analyze strong space weather disturbances during first ten days of September 2017, using the geomagnetic Dst index, parameters of normals to interplanetary shock fronts, direct measurements of interplanetary magnetic field, solar wind, and cosmic ray parameters. By applying spectral analysis methods to interplanetary medium data, we analyze MHD waves at the pre-front of two interplanetary shocks responsible for geomagnetic disturbances on September 6 and 7, 2017. The main results are as follows: the contribution of three branches of MHD waves (Alfvén, fast and slow magnetosonic) to the observed spectrum of the interplanetary magnetic field modulus has been established. We have confirmed the conclusion that the generation of Alfvén waves and fast magnetosonic waves is due to the presence of low-energy proton fluxes (Ep~1 MeV) at the pre-front of interplanetary shocks. We have also discovered a predominant contribution of slow magnetosonic waves to the observed spectrum of the interplanetary magnetic field modulus, but its reason is yet unknown. It is noted that different orientations of the normals to the interplanetary shock fronts and to the direction of the interplanetary magnetic field average vector on spacecraft located fairly close to each other may indicate waviness of the shock front structure.

MHD waves at the pre-front of interplanetary shocks on September 6 and 7, 2017

We analyze strong space weather disturbances during first ten days of September 2017, using the geomagnetic Dst index, parameters of normals to interplanetary shock fronts, direct measurements of interplanetary magnetic field, solar wind, and cosmic ray parameters. By applying spectral analysis methods to interplanetary medium data, we analyze MHD waves at the pre-front of two interplanetary shocks responsible for geomagnetic disturbances on September 6 and 7, 2017. The main results are as follows: the contribution of three branches of MHD waves (Alfvén, fast and slow magnetosonic) to the observed spectrum of the interplanetary magnetic field modulus has been established. We have confirmed the conclusion that the generation of Alfvén waves and fast magnetosonic waves is due to the presence of low-energy proton fluxes (Ep~1 MeV) at the pre-front of interplanetary shocks. We have also discovered a predominant contribution of slow magnetosonic waves to the observed spectrum of the interplanetary magnetic field modulus, but its reason is yet unknown. It is noted that different orientations of the normals to the interplanetary shock fronts and to the direction of the interplanetary magnetic field average vector on spacecraft located fairly close to each other may indicate waviness of the shock front structure.

Expression-based selection identifies a microglia-tropic AAV capsid for direct and CSF routes of administration in mice.

Microglia are critical innate immune cells of the brain. In vivo targeting of microglia using gene-delivery systems is crucial for studying brain physiology and developing gene therapies for neurodegenerative diseases and other brain disorders such as NeuroAIDS. Historically, microglia have been extremely resistant to transduction by viral vectors, including adeno-associated virus (AAV) vectors. Recently, there has been some progress demonstrating the feasibility and potential of using AAV to transduce microglia after direct intraparenchymal vector injection. Data suggests that combining specific AAV capsids with microglia-specific gene expression cassettes to reduce neuron off-targeting will be key. However, no groups have developed AAV capsids for microglia transduction after intracerebroventricular (ICV) injection. The ICV route of administration has advantages such as increased brain biodistribution while avoiding issues related to systemic injection. Here, we performed an in vivo selection using an AAV peptide display library that enables recovery of capsids that mediate transgene expression in microglia. Using this approach, we identified a capsid, MC5, which mediated enhanced transduction of microglia after ICV injection compared to AAV9. Furthermore, MC5 enhanced both the efficiency (85%) and specificity (93%) of transduction compared to a recently described evolved AAV9 capsid for microglia targeting after direct injection into the brain parenchyma. Exploration of the use of MC5 in a mouse models of Alzheimer's disease revealed transduced microglia surrounding and within plaques. Overall, our results demonstrate that the MC5 capsid is a useful gene transfer tool to target microglia in vivo by direct and ICV routes of administration.

Landmark knowledge overrides optic flow in honeybee waggle dance distance estimation.

Honeybees encode in their waggle dances the vector (distance and direction) of an outbound flight to a food source or a new nest site. Optic flow has been identified as the major source of information in the distance estimation. Additional components of distance estimation were also identified, e.g. the sequence of experienced landmarks. Here we address the question of whether bees also use the landscape memory developed during exploratory orientation flights to estimate distance. We took advantage of the fact that flights in a narrow tunnel lead to further distance measures due to higher optic flow. We find that this effect is lost when bees had explored the area in which the tunnel is located and when they have somewhat restricted visual access to the surrounding environment through the mesh on top of the tunnel. These data are interpreted in the context of other findings about the structure of navigational memory in bees that develops during exploratory orientation flights. In particular, the data suggest that bees embed distance measures into a representation of navigational space that stores previously experienced landscape features.

Reevaluation of Plate-Fin Heatsink Natural Convection Correlations for Sideways and Three-Dimensional Inclinations

The common orientations of the plate-fin heat sink for natural convection cooling of electronics are vertical and upward-facing horizontal. However, depending on various use scenarios, the heat sink may be inclined, intentionally or otherwise. In our previous papers concerning this subject, the author proposed a set of correlations for plate-fin heat sinks covering all inclination angles backward and forward (pitch rotation) from the vertical position of the heat sink. The set was based on a series of computational simulations with a validated model. At the time, tilting the heat sink sideways (roll rotation) was not considered. In the present study, though, the sideways inclination of the plate-fin heat sinks is simulated using our previous model only by adjusting the direction of the gravitational acceleration vector, thus requiring no additional validation. It is determined that the previously proposed correlation is valid up to 80° sideways inclinations of the heat sink. Interesting flow structures are observed when the heat sink is tilted 90° sideways. Furthermore, it is demonstrated that the correlation surprisingly remains valid if the heat sink is simultaneously rotated in both axes (pitch and roll).

Use of a confocal optical device for centring a diamond anvil cell in single-crystal X-ray diffraction experiments.

High-pressure crystallographic data can be measured using a diamond anvil cell (DAC), which allows the sample to be viewed only along a cell vector which runs perpendicular to the diamond anvils. Although centring a sample perpendicular to this direction is straightforward, methods for centring along this direction often rely on sample focusing, measurements of the direct beam or short data collections followed by refinement of the crystal offsets. These methods may be inaccurate, difficult to apply or slow. Described here is a method based on precise measurement of the offset in this direction using a confocal optical device, whereby the cell centre is located at the mid-point of two measurements of the distance between a light source and the external faces of the diamond anvils viewed along the forward and reverse directions of the cell vector. It is shown that the method enables a DAC to be centred to within a few micrometres reproducibly and quickly.

High accuracy patient-specific 3D coronary reconstruction from angiography and intravascular optical coherence tomography.

The integration of digital subtraction angiography (DSA) with intravascular optical coherence tomography (IVOCT) offers a comprehensive 3D arterial model, which is invaluable for the analysis of vascular anatomy and biomechanics. However, the process of image fusion is often hindered by the challenge of accurately orienting IVOCT images. This paper introduces a novel, to our knowledge, dual-path 3D reconstruction method that leverages the guidewire and the vessel's centerline to establish cross sectional direction vectors within the IVOCT images and spatial direction vectors along the guidewire's trajectory. This approach minimizes the accumulation of reconstruction errors by ensuring the precise orientation of each vascular cross section. The efficacy of the proposed method is validated through vascular phantom experiments and the reconstruction of patient-specific 3D coronary models.

Study on long short-term memory based on vector direction of flood process for flood forecasting

Accurate flood forecasting is crucial for flood prevention and mitigation, safeguarding the lives and properties of residents, as well as the rational use of water resources. The study proposes a model of long and short-term memory (LSTM) combined with the vector direction (VD) of the flood process. The Jingle and Lushi basins were selected as the research objects, and the model was trained and validated using 50 and 49 measured flood rainfall-runoff data in a 7:3 division ratio, respectively. The results indicate that the VD-LSTM model has more advantages than the LSTM model, with increased NSE, and reduced RMSE and bias to varying degrees. The flow simulation results of VD-LSTM better match the observed flow hydrographs, improving the underestimation of peak flows and the lag issue of the model. Under the same task and dataset, with the same hyperparameter settings, VD-LSTM can more quickly reduce the loss function value and achieve a better fit compared to LSTM. The proposed VD-LSTM model couples the vectorization process of flood runoff with the LSTM neural network, which contributes to the model better exploring the change characteristics of rising and receding water in flood runoff processes, reducing the training gradient error of input–output data for the LSTM model, and more effectively simulating flood process.

FACE: Feature-preserving CAD model surface reconstruction

Feature lines play a pivotal role in the reconstruction of CAD models. Currently, there is a lack of a robust explicit reconstruction algorithm capable of achieving sharp feature reconstruction in point clouds with noise and non-uniformity. In this paper, we propose a feature-preserving CAD model surface reconstruction algorithm, named FACE. The algorithm initiates with preprocessing the point cloud through denoising and resampling steps, resulting in a high-quality point cloud that is devoid of noise and uniformly distributed. Then, it employs discrete optimal transport to detect feature regions and subsequently generates dense points along potential feature lines to enhance features. Finally, the advancing-front surface reconstruction method, based on normal vector directions, is applied to reconstruct the enhanced point cloud. Extensive experiments demonstrate that, for contaminated point clouds, this algorithm excels not only in reconstructing straight edges and corner points but also in handling curved edges and surfaces, surpassing existing methods.

Accurate surface profile measurement using CMM without estimating tip correction vectors

Detailed measurement of the curved surface of an industrial product with a radius of curvature of less than a few millimeters is a challenging task for tactile coordinate measuring machines. To estimate a surface profile, tip radius correction is typically performed by estimating the tip correction vector direction. However, a substantial measurement error is introduced by the error in estimating the tip correction vector direction under measurement conditions such as a large position measurement error of an indicated measured point or a short sampling interval, In this study, a method that can estimate a surface profile by calculating the envelope of a probe tip path was proposed. The proposed method was experimentally and numerically confirmed to be able to estimate surface profiles with sub-micrometer accuracy under such measurement conditions.

Time division interferometer setups

Abstract A time division interferometer (TDI) in the optical regime is presented, where a wavetrain is temporally split into two distinct parts that are superimposed at a subsequent stage. At any one time, the photons have no alternatives, only one possible path is possible. There is no path bifurcation in the setup, i.e. no ‘Y’ where the photons can take left or right. The photons choice, if any, is to arrive/collapse before or after the time t 1 when the time modulated medium changes its state. In time-varying media, as energy can be exchanged between the wave and medium, the wave frequency is modified. Thus, the diverted photons become doubly tagged, in their wave vector direction as well as their frequency. A streak camera detector array resolves both, the fringe pattern as well as the frequency beats, in a space versus time interferogram. This apparatus has 0.66 ns temporal resolution and 70 μ m spatial resolution. Several TDI configurations are described, two of them are implemented: a spatio-temporal interferometer where the ‘which path’ criterion is readily observed and an all temporal TDI where only temporal interference is present. Novel possibilities of TDI schemes are discussed.

Determination of optimal directions of the wave vector of the phase holographic grating in cubic photorefractive crystal

The dependence of the change in the components of the inverse permittivity tensor of a cubic photorefractive Bi12SiO20 crystal on the direction of the wave vector of holographic grating in the crystal coordinate system has been studied. It is shown that, when recording a phase hologram, the largest change in the refractive index of Bi12SiO20 crystal is attained when the holographic grating wave vector is oriented along symmetrically equivalent 111 directions. The maximum possible modulation amplitude of the refractive index of a holographic grating with the wave vector oriented along the 110 directions is found to exceed that in the case of orientation along the 100 directions. The components of the inverse permittivity tensor of Bi12SiO20 crystal were calculated taking into account that a phase hologram is recorded under linear electro-optic, photoelastic, and inverse piezoelectric effects.

Quantum analogous spin states of ultrasonic guided waves

In quantum mechanics, spin is a physical property that dominates the topological behaviors. While manifesting the spin states they reveal complex interaction of physical parameters in a topological media. The guided waves’ inherent spin states are made of real physical spin angular momentum from the superposition of elastic waves. Thus, here the elastic spin state that naturally manifests by the ultrasonic guided waves in an elastic wave guide is explained through quantum analogous perspective. Guided wave modes are the superposition of two longitudinally polarized and two transverse polarized elastic wave potentials propagating in diverging and converging pattern. Spin nature of transverse waves is well known. Spin nature of longitudinal waves is also recently being explored. However, due to the unique modal superposition of guided Rayleigh-Lamb wave modes the physical understanding of spin state is incomplete for the guided waves in a bounded media. Unlike only one hybrid spin states described in earlier works, guided waves may manifest total six with four well defined hybrid spin states explicitly derived and explained in this article. These six spin states play crucial role in the physics of spin-momentum locking of guided waves. Two spin states originated from the interaction of similar potentials and four hybris spin states originated from the interaction of potentials with different directions of wave vector and polarization vector, as emerged in guided waves. Understanding from fundamentals and exploiting the phenomena of spin-momentum locking in guided waves may have several applications in nondestructive evaluation.

Beam test of n-type Silicon pad array detector at PS CERN

This work reports the test of an n-type silicon pad array detector at the CERN PS in the context of the future Forward Calorimeter (FoCal) detector. FoCal is a proposed upgrade in the ALICE detector operating within the pseudorapidity range of 3.2 < η < 5.8. It aims to measure direct photons, neutral hadrons, vector mesons, and jets for the study of gluon saturation effects in the unexplored region of low momentum fraction x (∼ 10-5–10-6). The prototype is a 8×9 n-type Si pad array detector with each pad occupying one cm2 area, fabricated on a 6-in, 325 ± 10 μm thick, and high-resistivity (∼ 7 kΩ cm) Si wafer, which is readout using the HGCROCv2 chip. The detector is tested using pion beams of energy 10 GeV and electron beams of energy 1–5 GeV. The measurements of the Minimum Ionizing Particle (MIP) response of pions and the shower profiles of electrons are reported.

Spin-dependent Goos-Hänchen shift for electron in single-layered semiconductor microstructure modulated by Rashba spin–orbit coupling

We theoretically investigate Goos-Hänchen effect for electron in single-layered semiconductor microstructure (SLSM) modulated by Rashba spin–orbit coupling (SOC). Due to the SOC effect, GH displacement is obviously dependent on spins, which allows electron spins to be separated in space dimension and results in spin polarization of electrons in semiconductors. Spin polarization ratio is associated with incident energy, incident direction and in-plane wave vector, e.g., it reaches maximum at resonance, but no spin polarization effect appears at normal incidence. In particular, both magnitude and sign of spin polarization ratio are controlled by external electric field or semiconductor-layer thickness, therefore, a manipulable spatial electron-spin splitter is obtained for semiconductor spintronics device applications.

Prior-free 3D human pose estimation in a video using limb-vectors

Estimating accurate 3D human poses from a monocular video is fundamental to various computer vision tasks. Existing methods exploit 2D-to-3D pose lifting, multiview images, and depth sensors to model spatio-temporal dependencies. However, depth ambiguities, occlusions, and larger temporal receptive fields pose challenges to these approaches. To address this, we propose a novel prior-free DCNN-based 3D human pose estimation method for monocular image sequences using limb vectors. Our method comprises two subnetworks: a limb direction estimator and a limb length estimator. The limb direction estimator utilizes a fully convolutional network to model limb direction vectors across a temporal window. We show that network complexity can be significantly reduced by utilizing dilated convolutional operations and a relatively smaller receptive field while maintaining estimation accuracy. Moreover, the limb length estimator captures stable limb length estimations from a reliable frame set. Our model has shown superior performance compared to existing methods on the Human3.6M and MPI-INF-3DHP datasets.