Zigzag Trajectories Research Articles

Courtship Behavior of Adult Spodoptera frugiperda (Lepidoptera: Noctuidae) Observed Using Track 3D Trajectory Tracking.

Spodoptera frugiperda, also known as the fall armyworm (FAW), is classified by the Food and Agriculture Organization of the United Nations (FAO) as a major agricultural pest. By gaining a more nuanced understanding of the fall armyworm's courtship behavior, simpler and more environmentally friendly methods of controlling this pest can be developed. This study used the Track 3D system to meticulously record and describe the activity characteristics and patterns of adult males and females during courtship. The results show that adult FAWs engaged in a variety of activities during courtship that were either discrete (flying, flapping, moving, and crawling), continuous (flapping + flying, flapping + crawling, and flying + crawling), or combined (flapping + touching + flapping; flying + touching + flying). Flying and flapping were the most common activities, with observed flight patterns consisting of parabolic, circular, and zigzag trajectories. The peak activity times for adult FAWs are mainly concentrated at 11:00 p.m., 3:00 a.m., and 5:00 a.m., providing fundamental data for the precise attraction and control of adult FAWs at later stages.

Habitat Factors that Determine the Movement of Sumatran Elephants at Bukit Barisan Selatan National Park

Until now, conflicts between elephants and the community are still occurring, one of which is in the Bukit Barisan Selatan National Park. This conflict has a negative impact on both elephants and society, so it is necessary to examine the habitat factors that determine the movement of Sumatran elephants. Therefore, the aim of this study is to determine the daily movement of the elephants and to analyze the habitat factors that influence elephant movement. Data was collected in the form of elephant movements in one period which were obtained from the Bukit Barisan Selatan National Park. 1-year results obtained from the GPS stated that there are two groups of elephants, the citra elephant group and the bunga elephant group. The results showed that groups of elephants in Bukit Barisan Selatan National Park have lengths that ranged from 63 – 137 kilometers, with linear, zigzag and circular trajectories, and the frequency of points used is 2-6 repetitions with the time needed per-kilometers ranging from 110 – 518 minutes. Factors that influence elephant movement are track length, frequency of point used, time spent per-kilometers, altitude, slope, distance to settlements, distance to water sources, availability of feed, and availability of scrubbing trees

Mid-Atlantic Bight cold pool based on ocean glider observations

During summer, distinctive, bottom-trapped, cold water mass of remnant local and remote winter water called Cold Pool Water (CPW) resides as a swath over the mid to outer continental shelf throughout much of the Mid-Atlantic Bight (MAB). This evolving CPW is important because it strongly influences the ecosystem, including several important fisheries. Thus, there is a priority to better understand the relevant ocean processes and develop CPW forecast capability. Over the past decade, repeated high-resolution Slocum glider measurements of ocean water properties along a New Jersey cross-shelf transect have helped to define the variability of the CPW structure off New Jersey. More recently the Mid-Atlantic Regional Association Coastal Ocean Observing System-supported ocean gliders have occupied a series of along-shelf zigzag trajectories from Massachusetts to New Jersey and New Jersey to Maryland. The comprehensive set of March through November 2007 glider measurements has been used to define the annual evolution of the 10 °C Cold Pool in terms of its distribution and water properties. The rather steady warming at the rate of 1 °C per month July through October 2007 is reflected in the 2007 CPW temperature (T) and salinity (S) properties. We describe how a three-glider fleet view of the September 2013 Cold Pool (a) confirmed the Lentz (2017) CPW cold patch and (b) the impingement of a Gulf Stream warm core ring warmed and salted the 2013 CPW. The Gulf Sream 2013 event forced our extension of the CPW T and S properties.

Settling behaviors of microplastic disks in water

Microplastic (MP) disks have not been studied for settling behaviors in aquatic environments, which affects the transport and fate of MPs. Therefore, settling experiments were conducted on MP disks of three shapes and four common-seen materials. Lighter MP disks (with density ρs = 1.038 g/cm3 and length l ≤ 5 mm) followed rectilinear vertical trajectories, while heavier MP disks (ρs = 1.161–1.343 g/cm3 and l = 5 mm) followed zigzag trajectories with oscillations and rotations. The mean terminal settling velocities of MP disks were 19.6–48.8 mm/s. Instantaneous settling velocities of heavier MP disks fluctuated. Existing formulas could not accurately predict the settling velocity of MP disks; thus, a new model was proposed with an error of 15.5 %. Finally, the Red - I* diagram (Red is the disk Reynolds number and I* is the dimensionless moment of inertia) was extended for MP disks to predict settling trajectories.

Trajectory engineering of directrons in liquid crystals via photoalignment.

As electrically generated solitons in liquid crystals, directrons represent intriguing structures promising extensive application prospects in the areas of microcargo vehicles, microreactors, and logic devices. However, manipulating directrons along elaborate predetermined trajectories still remains to be largely explored. In this work, the strategy of constructing high-resolution periodic alignment fields for directrons via the polarization holography photoalignment technique is presented. The optimum exposure dose for directrons to form over a broad range of electric fields is determined to be 32.4 J cm-2 for the alignment layers with 1 wt% azo dye SD1. Zigzag and fishhook-shaped trajectories of directrons are realized with two orthogonal polarized beams. The resolution for zigzag steering of directrons is evaluated to be approximately 56 μm to 80 μm, about three to four times the length of directrons. These results not only enrich the forms of motion of directrons, but also lay the foundations for customized trajectories of directrons in future developments.

Dynamics of a self-propelled compound droplet

A recent experiment by Wang et al. (Soft Matt., vol. 17, 2021, pp. 2985–2993) shows that a self-propelled compound drop in a surfactant-laden solution can autonomously change its motion from a straight line to a spiraling trajectory, enhancing its capability for chemical detection, catalytic reaction and pollutant removal in a large fluid region. To understand the underlying physics of this peculiar motion, we develop a two-dimensional minimal model to study the swimming dynamics of a compound droplet driven by a self-generated Marangoni stress. We find that, depending on the Péclet number ( $Pe$ ) and the viscosity and volume ratios of the two compound phases, the drop can swim in a variety of trajectories, including straight lines, circles, zigzag curves and chaotic trajectories. The drop moves in circles when its two components have comparable volumes. Otherwise, it shows other types of motions depending on $Pe$ . Our simulation results for the circular motion at small $Pe$ are qualitatively comparable to the experiment. The transition between zigzag and circular trajectories is mainly determined by the orientation of high-order modes with respect to the drop's swimming direction. For most compound drops, the speed decays as $Pe^{-1/3}$ at high Péclet numbers as it does for a single-phase drop. A drop with two equal components undergoes a run-and-reorient motion due to the competition between the even and odd modes.

High-temperature damage-tolerance of a hot-rolled brick-and-mortar Ti2Ni/TiNi composite

• Brick-and-mortar structure successfully realizes the potential of nacre-like structure. • Brick-and-mortar structure exhibits a high-temperature damage-tolerance up to 500 °C. • A zig-zag crack trajectory is inherited from the nacre-like structure. A nacre-like biomimetic Ti 2 Ni/TiNi brick-and-mortar composite, consisting of brittle Ti 2 Ni bricks homogeneously distributed in ductile TiNi mortars, is produced by hot rolling conventional laminated composite. When deformation temperature is between 25 and 500 °C, the brick-and-mortar composite essentially remains constants of fracture toughness (50 MPa·m 1/2 ) and flexural strength (1250 MPa). This is consistent with zig-zag crack trajectories inherited from the nacre-like structure, providing a strong extrinsic toughening. Further increasing the deformation temperature up to 700 °C dramatically deteriorates the flexural strength because the TiNi mortars are strongly softened. Therefore, the Ti 2 Ni/TiNi brick-and-mortar composite exhibits a high-temperature damage-tolerance up to 500 °C.

Gloss and Modelling Studies of Stone Polishing Using Linear Polishing Machines with Rotating Heads

The ornamental stone industry has always played an important role in the world economy. Polishing the slabs to increase their gloss is important to enhance the beauty and richness of these natural materials. Many industrial polishing machines rely on a rotating head’s movement along zigzag trajectories (controlled by belt, transverse and rotational speeds), to erode the surface as stochastically as possible (to avoid scratches and other visual defects caused by paths that are too symmetrical). Optimizing (and automatizing) these three speeds together therefore represents a significant gain for the industry, in time, energy, and quality of product. In this work we show that this optimization can be accomplished by fulfilling these conditions: (1) the displacement of the polishing head after a single zigzag movement should be smaller than its diameter; and (2) the displacement of the polishing head after a single rotation should be smaller than its radius. To assess the validity of these two conditions, we studied the polishing activity using experiments based on gloss measurements of the polished stone and computer simulations based on the geometric contacts between the tool and the stone. We concluded that: (i) a clear correlation can be established between experimental and simulation data; (ii) the two displacement parameters represent an effective way to control the quality and efficiency of the polishing process; and (iii) there is a limit to the gloss acquired through polishing processes, thus polishing above a given threshold decreases the efficiency without increasing the quality. The correspondence between experimental and modelling results opens the door to further optimizations of these polishing processes in the future.

Flow induced by the single-bubble chain depending on the bubble release frequency

In the present study, we experimentally investigated the flow induced by the in-chain bubbles (2.4–2.8 mm in size) while varying the bubble release frequency (fb=0–31 Hz), using high-speed two-phase particle image velocimetry and shadowgraphy. Along the streamwise (vertical) direction, we identified the transition of in-chain bubble dynamics and associated liquid flow. That is, the released bubbles tend to follow the straight path initially but transition to the oscillating (zigzag or spiral) trajectories. In particular, in the developing regime (near the nozzle), the coherent behavior of bubble chain generates the rib-like oblique jet flow, deviating from the rise path, even after the onset of the path instability of each bubble. As the flow develops, the scattering of rising path along the lateral direction becomes significant, and the liquid flow shows the similarity to the typical single-phase jet flow, which becomes more obvious at fb > 8 Hz. In this regime, with increasing the fb, the oscillating motion of bubbles changes to the flattened spiral one, and the deviation (fluctuation) of the lateral amplitude increases resulting from the enhanced flow-induced wobbling of bubble shape. Finally, we developed an analytical model to predict the evolution of time-averaged vertical velocity profile of the liquid, which considers the contributions of (i) local void fraction and (ii) evolution of upstream flow, and validated successfully with the measurement.

A Physics-Informed Neural Network for the Prediction of Unmanned Surface Vehicle Dynamics

A three-degrees-of-freedom model, including surge, sway and yaw motion, with differential thrusters is proposed to describe unmanned surface vehicle (USV) dynamics in this study. The experiment is carried out in the Qing Huai River and the data obtained from different zigzag trajectories are filtered by a Gaussian filtering method. A physics-informed neural network (PINN) is proposed to identify the dynamic models of the USV. PINNs combine the advantages of data-driven machine learning and physical models. They can also embed the speed and steering models into the loss function, which can significantly retain all types of information. Compared with traditional neural networks, the results show that the PINN has better generalization ability in predicting the surge and sway velocities and rotation speed with only limited training data.

Hydroacoustics for density and biomass estimations in aquaculture ponds

The use of hydroacoustics is currently being studied and developed as a promising non-intrusive methodology to monitor and manage fish stocks in aquaculture farms. The main objective of this study was to develop an acoustic method for the estimation of fish density and biomass in inland aquaculture farms and test the accuracy and precision of the estimates with real data provided by the company. The study was conducted in sea bass (Dicentrarchus labrax) production ponds located in Seville (Southern Spain). A Simrad EK60 echosounder with two split-beam circular transducers operating simultaneously at 200 kHz was used for hydroacoustic surveys. Two different hydroacoustic designs were considered: central trajectories and zigzag trajectories. The accuracy and precision of the estimates were examined in order to select the best sampling design. Due to a non-homogeneous fish distribution in the pond caused by the avoidance behaviour, as a response to the sampling disturbance presented by fish, acoustic density and biomass were corrected by applying sampling theory according to the probability of fish detection. When density and biomass were corrected, the estimates became highly accurate and precise with respect to real data, which confirms that the proposed method is adequate. Similarly, acoustic estimates of fish weight were highly in agreement with real data, due to the use of specific equations developed “in situ” for the study. Although no significant differences were recorded in the density and biomass estimates with regard to the trajectory used (central vs. zigzag), it was observed that the most accurate agreement and precision were always obtained in central trajectories. Therefore, central design is proposed as the most appropriate design for hydroacoustic measurements in inland ponds. The results obtained in this study provide estimates of density and biomass that accurately match the real data, supporting the use of hydroacoustics as a potentially valid tool to manage inland aquaculture farms.

Three dimensional tracking of a maneuvering emitter utilizing doppler-bearing measurements of a constant velocity observer

This manuscript handles a 3-D tracking problem, in which a 3-D observer with a constant velocity estimates the emitter state (position and velocity) while measuring the emitter’s elevation, azimuth angle, and doppler frequency. Conventional tracking filters are built assuming a constant velocity emitter, thus have difficulty in tracking a maneuvering emitter. This manuscript introduces the filter restart approach for tracking a maneuvering emitter in 3-D environments. As far as we know, this manuscript is novel in 3-D doppler-bearing problems so that a constant velocity observer can track a maneuvering emitter with zigzag trajectories. This paper is unique in presenting the observability analysis of 3-D doppler-bearing problems. The performance of the proposed tracking filter is verified by comparing it with 3-D Interacting Multiple Model Kalman filters under MATLAB simulations.

KINEMATIC OSCILLATIONS OF POST-CME BLOBS DETECTED BY K-COR ON 2017 SEPTEMBER 10

We investigate 20 post-coronal mass ejection (CME) blobs formed in the post-CME current sheet (CS) that were observed by K-Cor on 2017 September 10. By visual inspection of the trajectories and projected speed variations of each blob, we find that all blobs except one show irregular zigzag trajectories resembling transverse oscillatory motions along the CS, and have at least one oscillatory pattern in their instantaneous radial speeds. Their oscillation periods are ranging from 30 to 91 s and their speed amplitudes from 128 to 902 km s-1. Among 19 blobs, 10 blobs have experienced at least two cycles of radial speed oscillations with different speed amplitudes and periods, while 9 blobs undergo one oscillation cycle. To examine whether or not the apparent speed oscillations can be explained by vortex shedding, we estimate the quantitative parameter of vortex shedding, the Strouhal number, by using the observed lateral widths, linear speeds, and oscillation periods of the blobs. We then compare our estimates with theoretical and experimental results from MHD simulations and fluid dynamic experiments. We find that the observed Strouhal numbers range from 0.2 to 2.1, consistent with those (0.15-3.0) from fluid dynamic experiments of bluff spheres, while they are higher than those (0.15-0.25) from MHD simulations of cylindrical shapes. We thus find that blobs formed in a post-CME CS undergo kinematic oscillations caused by fluid dynamic vortex shedding. The vortex shedding is driven by the interaction of the outward-moving blob having a bluff spherical shape with the background plasma in the post-CME CS.

Ensemble learning approach based on stacking for unmanned surface vehicle's dynamics

The 3 degrees of freedom (DOF) model, including surge motion, sway motion and yaw motion, with differential thruster is proposed to describe the unmanned surface vehicle (USV)'s dynamics. The experiment is carried out in the Qing-huai river and the data obtained from different zigzag trajectories is filtered by gaussian filtering method. The base learners, Backpropagation (BPNN), Support vector machine (SVM) with RBF kernel and SVM with Linear kernel, are selected to identify the dynamic model of USV. To guarantee that base learners have a strong robustness and generalization ability, the initial weights in BPNN and hyper-parameters in SVM are optimized by cross validation (CV), genetic algorithm (GA), particle swarm optimization (PSO) and cuckoo search algorithm (CS) method. The results show that the CS method has a better optimal capacity in predicting the USV's dynamics. These methods on prediction USV's dynamics have their own advantages and disadvantages. Furthermore, The Ensemble learning (EL) method, called stacking, integrating these base learners is firstly proposed to identify the USV's dynamics. The results demonstrate that the EL method has more accuracy in identifying the dynamic models than base-learners.

Active-quadrupole interaction of Bessel beams and their influence on atoms

This paper explains how the optical quadrupole interaction between a two-level neutral atom and two counter-propagating non-diffracting Bessel beams can exhibit interesting rotational characteristics. It shows that, in this case, the atom dynamics are determined by a radiation pressure force as well as a gradient quadrupole force. Under appropriate circumstances, neutral atoms are able to rotate with zig-zag trajectories in specific spaces inside annular shapes produced by quadrupole potential. This occurs especially when Bessel beam.

Exceptional points and their coalescence ofPT-symmetric interface states in photonic crystals

The existence of surface electromagnetic waves in the dielectric-metal interface is due to the sign change of real parts of permittivity across the interface. In this work, we demonstrate that the interface constructed by two semi-infinite photonic crystals with different signs of the imaginary parts of permittivity also supports surface electromagnetic eigenmodes with real eigenfrequencies, protected by $ PT $ symmetry of such loss-gain interface. Using a multiple scattering method and full wave numerical methods, we show that the dispersion of such interface states exhibit unusual features such as zig-zag trajectories or closed-loops. To quantify the dispersion, we establish a non-Hermitian Hamiltonian model that can account for the zig-zag and closed-loop behaviour for arbitrary Bloch momentums. The properties of the interface states near the Brillouin zone center can also be explained within the framework of effective medium theory. It is shown that turning points of the dispersion are exceptional points (EPs), which are characteristic features of non-Hermitian systems. When the permittivity of photonic crystal changes, these EPs can coalesce into higher order EPs or anisotropic EPs. These interface modes hence exhibit and exemplify many complex phenomena related to exceptional point physics.

Comparative Efficiency Analysis of Data Fusion Methods for Vehicle Trajectory Reconstruction

This article compares the efficiency of vehicle trajectory analysis methods based on data fusion from multiple cameras, monitoring the same area from different views under the condition having detection errors, which causes incorrectly localized and, in some cases, undetected vehicle during the movement. The experiment used the simulation of detection and localization of vehicle moving in straight, curved, zigzag and arbitrary trajectories, with localization errors and multi-level loss of data. By comparing Kalman-filter-based method and Linear-interpolation-based method for analyzing and reconstructing vehicle trajectory, the result shows that the data loss robustness of Kalman-filter-based method is higher than that of Linear-interpolation-based method, with data loss around 97% 97% and 90% for straight, curved and zigzag trajectories respectively. However, for arbitrary trajectory, the Linear-interpolation-based method is better than Kalman-filter-based method in all levels of data loss. In conclusion, Kalman-filter-based method is effective in the case of unchanged or slight transition of direction, while Linear-interpolation-based method is effective in the case of sudden transition of direction.

And Where are Fluctuations In Quantum-Mechanical Wave Function?

The generalized complex numbers containing weight coefficients for a paraxial case are described. An evident analogy between the wavy systems of trajectories, the module and an argument of complex numbers and the module and an argument of wave functions is drawn.Their geometrical interpretation is given on the plane and on the sphere. The symmetric and asymmetrical systems of wavy trajectories are considered. The examination of different types of wavy and zigzag trajectories of our systems of rays is presented. An evident analogy of these systems and wave functions describing finding of an electron in a potential well and near an atomic nucleus is drawn. The possible arrangement of a wave of de Broglie of an electron on the sphere of Bohr radius is shown. In the offered work great mathematicians whose works are connected with researches of complex numbers are marked out in {braces}: {Cardano, Hamilton, Gauss, Cauchy and Euler}.

Integrating planned and reactive behaviors for exploration coordination of multi-robot systems

To realize efficient exploration, a novel coordinated algorithm which integrated planned and reactive behaviors is proposed in this paper. The planned behaviors realize dispersion of robots over an environment, cooperation among robots and task assignments to robots. The behaviors are discussed fro m a case that the robot team size equals four in a kind of obstacle free environments. Afterwards, the behaviors are used to coordinate robot team with any size by utilizing a concept of compound robot. Reactive behaviors are used to deal with appearance of different outline obstacles in a kind of sparsely occupied environments. Then, a finite state machine is utilized to integrate these behaviors. For the two kinds of environments, robots conduct a set of zigzag and distorted zigzag trajectories, respectively. Finally, the results are validated by computer simulations.

Integrating predicate reasoning and reactive behaviors for coordination of multi-robot systems

To overcome computational expensive problem in coordination of multi-robot systems (MRS) for unknown environment explorations, an integrated coordinated algorithm is proposed in this paper. The algorithm integrated predicate based reasoning and reactive behaviors to realize coordination and obstacle avoidance. An MRS partitioning strategy is proposed to reduce the scale of problem. Then, an initialization strategy realizes dispersion of robots over the environment, and task assignments at the beginning. When a robot has finished its task, predicate based reasoning is used to assign task and to realize cooperative exploration among robots. Robots explore the unknown environment through a series of zigzag trajectories. To deal with obstacle avoidance, a few of reactive behaviors are defined. Supervisors are resident in middle level of a hierarchical architecture for each robot. The results are validated by computer simulations.