Motion Process Research Articles

Market Liquidity Estimation in a High-Frequency Setup

This article deals with the identification of a superior forecasting method for market liquidity using a calibrated Heston model for the bid/ask price path simulation instead of a standard Brownian motion, as well as a compound Poisson process and inverse transform sampling for the generation of the bid/ask volume distribution. We show that the simulated trading volumes converge to one single value, which can be used as a liquidity estimator, and find that the calibrated Heston model as well as the inverse transform sampling are superior to both the use of standard Brownian motion and compound Poisson process.

Real-Time Cargo Loading Identification Based on Self-Powered Camera

In practice, the statistics of cargo loading capacity needs to be realized by counting the loading actions. Object detection algorithm may not meet the requirements of such tasks under the influence of environmental factors. And the current temporal action localization methods may ignore the spatial information of objects and identify the inaccurate action time boundary of multiple objects in the cargo loading task. To fill this technical gap, this paper designs a cargo loading identification framework. The core of this framework is the Target Area Rise-descend (TAR) algorithm, which is based on the object detection model and uses the regularity of object location and object size to realize real-time recognition of the cargo loading process. We ensure the real-time and robustness of the algorithm by some means like nap mechanism and time regularity. The garbage truck recycling task is taken as an example to complete the elaboration of the proposed method. Experiments show that the accuracy of the proposed method is higher than 99%, and the real-time performance is higher than 20fps on Neural Network Computing Unit (NPU). Considering the limitations of intelligent application scenarios and resources, self-powered camera is applied. For mechanical motion similar to the scene in this paper, the proposed algorithm can use extremely low computing power to capture the motion process and achieve data statistics.

Anomalous diffusion, nonergodicity, non-Gaussianity, and aging of fractional Brownian motion with nonlinear clocks.

How do nonlinear clocks in time and/or space affect the fundamental properties of a stochastic process? Specifically, how precisely may ergodic processes such as fractional Brownian motion (FBM) acquire predictable nonergodic and aging features being subjected to such conditions? We address these questions in the current study. To describe different types of non-Brownian motion of particles-including power-law anomalous, ultraslow or logarithmic, as well as superfast or exponential diffusion-we here develop and analyze a generalized stochastic process of scaled-fractional Brownian motion (SFBM). The time- and space-SFBM processes are, respectively, constructed based on FBM running with nonlinear time and space clocks. The fundamental statistical characteristics such as non-Gaussianity of particle displacements, nonergodicity, as well as aging are quantified for time- and space-SFBM by selecting different clocks. The latter parametrize power-law anomalous, ultraslow, and superfast diffusion. The results of our computer simulations are fully consistent with the analytical predictions for several functional forms of clocks. We thoroughly examine the behaviors of the probability-density function, the mean-squared displacement, the time-averaged mean-squared displacement, as well as the aging factor. Our results are applicable for rationalizing the impact of nonlinear time and space properties superimposed onto the FBM-type dynamics. SFBM offers a general framework for a universal and more precise model-based description of anomalous, nonergodic, non-Gaussian, and aging diffusion in single-molecule-tracking observations.

Particle motion analysis and performance investigation of a fertilizer discharge device with helical staggered groove wheel

Enhancing the uniformity of fertilizer particles flow is crucial in fertilizer discharge device research, and the analysis of particle motion process contributes to improving fertilization performance. In this study, the discrete element method was employed to conduct a phenomenological analysis and numerical investigation of the particle motion characteristics influenced by structural feature parameters of the groove wheel-type fertilizer discharge device. A performance evaluation model based on the uniformity of fertilizer discharge and supplemented by the flow characteristics and mechanical properties of particles was established. The results demonstrated that the particles flow within the fertilizer bin exhibits a recirculating surge induced by the rotation of the groove wheel. The geometric morphology of the outer edge grooves and their spatial distribution along the groove wheel circumference affect the uniformity of fertilizer filling and discharge mass flow rate. The force exerted on the fertilizer particles and their potential breakage are primarily concentrated during the fertilizer compaction stage, while the particles flow forms a convergence due to the sliding of the fertilizer along the discharge slope. After optimization, the discharge CV is reduced from 91.54 % to 31.48 %, and the uniformity is improved by 60.06 %. This study proposes a helical staggered groove wheel fertilizer discharge device structural model, providing new insights for the optimization of agricultural fertilization machinery equipment.

Multifractional Hermite processes: Definition and first properties

We define multifractional Hermite processes which generalize and extend both multifractional Brownian motion and Hermite processes. It is done by substituting the Hurst parameter in the definition of Hermite processes as a multiple Wiener–Itô integral by a Hurst function. Then, we study the pointwise regularity of these processes, their local asymptotic self-similarity and some fractal dimensions of their graph. Our results show that the fundamental properties of multifractional Hermite processes are, as desired, governed by the Hurst function. Complements are given in the second order Wiener chaos, using facts from Malliavin calculus.

Analysis of trans‐domain motion process of bullet‐shaped trans‐domain amphibious vehicle

AbstractA fully functional prototype of a bullet‐shaped trans‐domain amphibious vehicle with the ability to perform reciprocating cross‐medium movements has been developed. Once the bullet‐shaped underwater vehicle completes its designated underwater tasks, upon reaching a suitable location for surface observation, it will transform into a bullet‐shaped coaxial counter‐propeller aircraft to carry out cross‐domain out‐of‐water and performing aerial flight missions. The successful transition of the vehicle into amphibious mode is attributed to the design of an innovative energy attitude multiplexing mechanism. Simultaneously, a rational and effective hybrid‐switching strategy has been proposed to enhance the reliability of the vehicle's amphibious mode transition. In view of the complex and changeable cross‐domain environment, we have adopted a modular design concept, breaking down the entire cross‐domain movement process into three key phases: air operation flight, transient cross‐domain, and underwater active sailing. Detailed theoretical analysis, algorithm design, and experimental research have been conducted for each phase. This paper proposes and expounds the key design principles, evaluates the performance indicators of key components, and weighs the matching of body dynamics and propulsion performance to ensure that the vehicle achieves the expected performance. Finally, the success of the test at different phases further proves that the vehicle has the ability to achieve complete cross‐domain operation.

Simulation of artificial anal sphincter motion and interaction with intestinal environment using SOFA.

Artificial anal sphincter is an implantable medical device for treating fecal incontinence. Reasonable simulation facilitates the advancement of research and reduces experiments on biological tissue. However, the device's clamping motion and sensor interaction with the intestine in the simulation still require further exploration. This article presents a simulation of the artificial anal sphincter's clamping and sensing and its interaction with the intestinal environment using the Simulation Open Framework Architecture (SOFA). Firstly, the proposed simulation algorithm and its principles in SOFA are analyzed. Secondly, the clamping motion and sensor system of the artificial anal sphincter are simulated. Thirdly, a finite element model of intestine is established based on the properties of intestinal soft tissue. Finally, the in vitro experiments are performed. The simulation results indicate that the sensor system of the artificial anal sphincter has good sensing performance during the clamping motion and fecal accumulation process. Experiments have shown that optimal sensory capabilities can be achieved as the posture of the artificial anal sphincter with a roll angle between 20° and 40°. The comparison demonstrates a mean absolute error of 10%-20% between simulation and in vitro experimental results for sensor forces, which verifies the effectiveness of the simulation. The proposed novel simulation achieves a more comprehensive interaction between the artificial anal sphincter motion and intestinal environment. This study may provide more effective simulation data for guidance in improving the performance of sensor perception of artificial anal sphincter for further research.

A Robot Motion Learning Method Using Broad Learning System Verified by Small-Scale Fish-Like Robot.

The widespread application of learning-based methods in robotics has allowed significant simplifications to controller design and parameter adjustment. In this article, robot motion is controlled with learning-based methods. A control policy using a broad learning system (BLS) for robot point-reaching motion is developed. A sample application based on a magnetic small-scale robotic system is designed without detailed mathematical modeling of the dynamic systems. The parameter constraints of the nodes in the BLS-based controller are derived based on Lyapunov theory. The design and control training processes for a small-scale magnetic fish motion are presented. Finally, the effectiveness of the proposed method is demonstrated by convergence of the artificial magnetic fish motion to the targeted area with the BLS trajectory, successfully avoiding obstacles.

Coupled CFD-DEM simulation of submarine landslide movement behavior

Submarine landslide is a common disaster geological phenomenon in the ocean, which can be destructive to underwater infrastructure. Therefore, it is necessary to simulate the evolutionary behavior of submarine viscous landslides. In this paper, computational fluid dynamics (CFD) and discrete element method (DEM) are used to establish the fluid-solid coupling model of water-particle interaction. Firstly, the inter-particle cohesion model is introduced to train the coupled CFD-DEM analysis of the kinematic evolution process, and at the same time, two typical cases are carried out to verify the analysis. In the experimental simulation, the kinematic and morphological characteristics of the submarine landslide were simulated considering the viscous effect and initial velocity of the landslide, and the influence mechanism of the landslide motion and evolution process was investigated in depth. The results show that the coupled method can better simulate the motion of submarine landslide, and the viscous effect of the landslide has a significant influence on its kinematic and morphological characteristics, and the initial velocity also significantly affects the evolution and distribution characteristics of the particle flow field of each part of the landslide in the process of motion. This study is important for the simulation and effective prediction of the kinematic evolution process of real submarine landslides.

‘Unsticking’ Kid Cosmic: Lifting the burden of gendered certainty in children’s TV

In recent years, American children’s animated TV has slowly begun to depict queerness in explicit ways, with a handful of shows portraying gender non-conforming characters and same-gender relationships. Still others have provided pathways to reading queer alterity in an absence of apparent queerness by celebrating and embracing uncertainty, change and difference. This article focuses on the latter in relation to textual analysis, exploring ‘unsticking’ in Kid Cosmic, an animated show that turns over and complicates the neo-liberal, individualistic superhero tropes typical of many comic books and comic book movies. Following Kid and his three companions as they negotiate newfound powers, the show offers the opportunity to read queerness in children and children’s TV not as an additive quality or monolithic struggle but rather as a fluid, uncertain, unfixed and ever-changing process of motion. As Kid and his companions’ bodies are transcendently lifted from existing representational frameworks and thrown through space – unstuck from the ground and from their daily lives – they come to comprise something, I argue, quite radical.

Study on the performance of spherical collision triboelectric nanogenerator

The development of the theoretical model for the spherical collision triboelectric nanogenerator (SC-TENG) has been slow, despite its ability to generate electric energy through low-frequency vibration while simultaneously reducing the motion response of the primary system. Previous theoretical models have solely focused on energy harvesting, disregarding the damping effect of spherical collisions. This paper presents an electromechanical coupling control equation, which accounts for the dynamic and electrical characteristics of spherical particles, to describe the relationship between motion displacement, velocity, acceleration, and particle number. The particle motion process is divided into two phases: non-collision and collision process. Using the constant velocity before and after collision, this paper calculates voltage and current changes corresponding to two collisions of particles in one cycle. Cadence software simulates and analyzes the equivalent circuit parameters of the TENG, where output voltage is proportional to the resistor/capacitor. Single, two, and three-particle acceleration, velocity, and displacement before and after collision are simulated using Abaqus software. Particle collision simulation shows the energy loss is related to the number of particles, the more the number of particles, the more the energy loss. The single-degree-of-freedom experimental model tests vibration reduction and energy collection effects of particles. As mass ratio increases, the vibration reduction and energy collection effects improve for particles. If the mass ratio remains constant, the vibration reduction effect does not vary much for different particle diameters (10/12/15 mm), but the energy collection effect of particle diameter of 10 mm is superior. Multi-layer particles, vibration control, voltage and current increase linearly with the number of layers. SC-TENG can be applied in the future to reduce structural vibration, while its additional energy collection capabilities can be as self-powered sensing to monitor movement of vibrating structures in real-time.

Duration and damping for ground motion characterization in frequency‐domain damage estimation of SDOF structures

AbstractIn estimating the damage to a single‐degree‐of‐freedom (SDOF) structure due to multiple earthquake events, it may be convenient to use a frequency‐based approach, in which the anticipated ground motions are characterized through power spectral density functions (PSDFs) compatible with the specified design spectra for those motions. Since a spectrum‐compatible PSDF corresponds to a fictitious stationary ground motion process of a specified duration, the duration of this process should preferably be same as the length of the stationary segment in the actual ground acceleration process for a meaningful computation of the stochastic response. On assuming the strong‐motion segment of a given ground motion to represent its stationary segment, the nonstationarity of the strong‐motion segment is evaluated for the existing strong‐motion duration definitions. It is found that the Trifunac‐Brady definition is the most reasonable strong‐motion duration definition in respect of consistently giving the longest strong‐motion segment with least nonstationarity. Further, a spectrum‐compatible PSDF can be used for estimating the stochastic response of a linear system, provided the system has the same damping ratio as that of the design spectrum from which the PSDF has been computed. This causes errors in estimating the peak response of an equivalent linear system due to its damping ratio being higher than the initial damping ratio of the nonlinear system. To address this, an empirical expression is developed for the modified damping ratio of a linear system, which would lead to the correct peak response of the system on using the PSDF obtained from the 5%‐damping design spectrum.

Aerodynamic behavior of flaky spalled blocks in high-speed rail tunnel lining under slipstream

As high-speed railway tunnels continue to serve for long periods of time, the tunnel lining is subjected to long-term cyclic tension and compression from train aerodynamic loads, thereby causing cracks to propagate and spalled blocks to fall off, which severely impact the safety of train operation. This paper is based on the improved delayed detached eddy simulation (IDDES) method and establishes a 3D fluid–solid coupling calculation model of spalled block-high-speed train-tunnel-air. Explores the differences in the motion trajectory and force of spalled blocks falling off at different peeling times under the impact of a high-speed train traveling at 300 km/h, and investigates the relationship between the spalled blocks and the changes in train aerodynamic flow field structure and aerodynamic pressure during the motion process in order to understand the aerodynamic behavior and flow field structure mechanism of spalled blocks. Under the action of slipstream, the spalled blocks exhibit a combined form of translation and rotation while falling, with the translation mainly occurring in the longitudinal (X-axis) direction and the rotation being most obvious around the Z-axis. Some significant differences are observed in the translational trajectory and rotational angle of the spalled blocks in the vertical and horizontal directions at different peeling times, and the longitudinal displacement distance is 3 to 38 times the horizontal displacement distance. The maximum rotational angle of the spalled block that peels off when the train head arrives is along the Z-axis.

Working at the limit: a review of thermodynamics and optimality of the Earth system

Abstract. Optimality concepts related to energy and entropy have long been proposed to govern Earth system processes, for instance in the form of propositions that certain processes maximize or minimize entropy production. These concepts, however, remain quite obscure, seem contradictory to each other, and have so far been mostly disregarded. This review aims to clarify the role of thermodynamics and optimality in Earth system science by showing that they play a central role in how, and how much, work can be derived from solar forcing and that this imposes a major constraint on the dynamics of dissipative structures of the Earth system. This is, however, not as simple as it may sound. It requires a consistent formulation of Earth system processes in thermodynamic terms, including their linkages and interactions. Thermodynamics then constrains the ability of the Earth system to derive work and generate free energy from solar radiative forcing, which limits the ability to maintain motion, mass transport, geochemical cycling, and biotic activity. It thus limits directly the generation of atmospheric motion and other processes indirectly through their need for transport. I demonstrate the application of this thermodynamic Earth system view by deriving first-order estimates associated with atmospheric motion, hydrologic cycling, and terrestrial productivity that agree very well with observations. This supports the notion that the emergent simplicity and predictability inherent in observed climatological variations can be attributed to these processes working as hard as they can, reflecting thermodynamic limits directly or indirectly. I discuss how this thermodynamic interpretation is consistent with established theoretical concepts in the respective disciplines, interpret other optimality concepts in light of this thermodynamic Earth system view, and describe its utility for Earth system science.

Recent Advances in Cerium Oxide-Based Memristors for Neuromorphic Computing.

This review article attempts to provide a comprehensive review of the recent progress in cerium oxide (CeO2)-based resistive random-access memories (RRAMs). CeO2 is considered the most promising candidate because of its multiple oxidation states (Ce3+ and Ce4+), remarkable resistive-switching (RS) uniformity in DC mode, gradual resistance transition, cycling endurance, long data-retention period, and utilization of the RS mechanism as a dielectric layer, thereby exhibiting potential for neuromorphic computing. In this context, a detailed study of the filamentary mechanisms and their types is required. Accordingly, extensive studies on unipolar, bipolar, and threshold memristive behaviors are reviewed in this work. Furthermore, electrode-based (both symmetric and asymmetric) engineering is focused for the memristor's structures such as single-layer, bilayer (as an oxygen barrier layer), and doped switching-layer-based memristors have been proved to be unique CeO2-based synaptic devices. Hence, neuromorphic applications comprising spike-based learning processes, potentiation and depression characteristics, potentiation motion and synaptic weight decay process, short-term plasticity, and long-term plasticity are intensively studied. More recently, because learning based on Pavlov's dog experiment has been adopted as an advanced synoptic study, it is one of the primary topics of this review. Finally, CeO2-based memristors are considered promising compared to previously reported memristors for advanced synaptic study in the future, particularly by utilizing high-dielectric-constant oxide memristors.

Two-Dimensional Fractional Order Iterative Learning Control for Repetitive Processes

The convergence and robustness rejecting parameters variations and external disturbance of the system are crucial for repetitive processes. In this paper, a two-dimensional robust fractional-order iterative learning control (FOILC) is proposed for the repetitive motion process to enhance the convergence and robustness. A fractional-order proportional derivative function (FOPDF) is designed as the control variable to replace the tracking error of the integer-order iterative learning control (IOILC) algorithm. The required dynamic output fractional-order iterative learning controller is constructed by solving a set of linear matrix inequalities (LMI), and the control parameters are adjusted according to the given specifications. Simulation and experimental results in robot torque control are given to prove the effectiveness and feasibility of the proposed design method.

Supremum Distribution of Weighted Sum of Random Processes from Orlicz Spaces of Exponential Type with Continuous Deviation

The paper studies distribution of sum of random processes from Orlicz spaces of exponential type weighted by continuous functions, in particular, processes from spaces Subϕ (Ω), SSubϕ (Ω) and class V (ϕ, ψ) are considered. Such spaces and classes of random variables and corresponding stochastic processes provide generalizations of Gaussian and sub-Gaussian random variables and processes and are important for various applications, for example, in queuing theory and financial mathematics. We derive the estimates for the distribution of supremum of weighted sum of such processes deviated by a continuous monotone function using the entropy method. As examples, weighted sum of Wiener and weighted sum of fractional Brownian motion processes with different Hurst indices from classes V (ϕ, ψ) are considered. Corresponding estimates of the probability of exceeding by trajectories of such weighted sums a positive level determined by a linear function are obtained. In the insurance risk theory, such aproblem arises during estimating a ruin probability of the corresponding risk process with a constant premium income, and in the communications theory, it appears for the buffer overflow probability for a single server with a constant service rate.

Flight Path Setting and Data Quality Assessments for Unmanned-Aerial-Vehicle-Based Photogrammetric Bridge Deck Documentation.

Imagery from Unmanned Aerial Vehicles can be used to generate three-dimensional (3D) point cloud models. However, final data quality is impacted by the flight altitude, camera angle, overlap rate, and data processing strategies. Typically, both overview images and redundant close-range images are collected, which significantly increases the data collection and processing time. To investigate the relationship between input resources and output quality, a suite of seven metrics is proposed including total points, average point density, uniformity, yield rate, coverage, geometry accuracy, and time efficiency. When applied in the field to a full-scale structure, the UAV altitude and camera angle most strongly affected data density and uniformity. A 66% overlapping was needed for successful 3D reconstruction. Conducting multiple flight paths improved local geometric accuracy better than increasing the overlapping rate. The highest coverage was achieved at 77% due to the formation of semi-irregular gridded gaps between point groups as an artefact of the Structure from Motion process. No single set of flight parameters was optimal for every data collection goal. Hence, understanding flight path parameter impacts is crucial to optimal UAV data collection.

Augmented Reality in a Lean Workplace at Smart Factories: A Case Study

The last few years have seen a massive transformation of the global industrial landscape, thanks to the emergence of Industry 4.0 and the disruptive technologies it enables, such as Augmented Reality (AR). This paper presents the result of a project with the primary focus on enhancing the operators’ working conditions and the further definition of the most suitable AR for each material handling and motion process. To achieve this, a methodology called Risk Assessment for Ergonomics and Safety in Logistics (RAES-Log) was developed in order to analyse and define AR implementation requirements, in order to mitigate existing risks and improve ergonomic conditions. Utilizing a human-centric approach consistent with Lean Thinking and Industry 5.0 vision, the main aim was to reduce human effort during task performance. Furthermore, the potential for creating waste-free and more efficient workspaces was explored, as well as the possibility of Human Augmentation (HA) to enhance workers’ capabilities and senses. The workers’ opinions and acceptance of the proposed AR solutions resulting from the RAES-Log methodology in a case study were collected and analysed. The overall feedback was positive and it is expected a lower prevalence of work-related Musculoskeletal Disorders (MSD), less lost time days, and lower injury severity, as well as increased process efficiency, operator motivation, well-being and engagement in continuous improvement processes.

Minimal model of diffusion with time changing Hurst exponent

We introduce the stochastic process of incremental multifractional Brownian motion (IMFBM), which locally behaves like fractional Brownian motion with a given local Hurst exponent and diffusivity. When these parameters change as function of time the process responds to the evolution gradually: only new increments are governed by the new parameters, while still retaining a power-law dependence on the past of the process. We obtain the mean squared displacement and correlations of IMFBM which are given by elementary formulas. We also provide a comparison with simulations and introduce estimation methods for IMFBM. This mathematically simple process is useful in the description of anomalous diffusion dynamics in changing environments, e.g. in viscoelastic systems, or when an actively moving particle changes its degree of persistence or its mobility.