Shape Of Path Research Articles

A goodness-of-fit test for functional time series with applications to Ornstein-Uhlenbeck processes

High-frequency financial data can be collected as a sequence of time-ordered curves, such as intraday prices. The Functional Data Analysis (FDA) framework offers a powerful approach to uncover information embedded in the shape of the daily paths, often unavailable from classical statistical methods. A novel goodness-of-fit test for autoregressive Hilbertian (ARH) models is introduced, imposing only the Hilbert-Schmidt condition on the autocorrelation operator. The test statistic is formulated in terms of a Cramér–von Mises norm, with calibration achieved via a wild bootstrap resampling procedure. A simulation study examines the test's finite-sample performance in terms of power and size. Furthermore, a new specification test for diffusion models, including Ornstein-Uhlenbeck processes, is proposed, illustrated with an application to intraday currency exchange rates. Specifically, a two-stage methodology is proffered: firstly, the relationship between functional samples and their lagged values is assessed using an ARH(1) model; second, under linearity, a functional F-test is conducted..

Effects of price path shapes and decision frames on emotions and investment decisions: Experimental evidence

We extend the literature on emotions and financial decisions by varying the agent (private investor, fund manager, delegation to a fund manager) in an investment experiment. We additionally vary the decision situation (buy or sell) and the shape of displayed price paths (convex, concave, or straight). We measure the investment behavior and the emotional valence evoked by the price paths. Independent of the type of agent, we confirm that price path shapes are related to investment behavior and emotions. In particular, concave shapes are associated with lower investments and valence. Finally, we provide evidence for a mediating role of valence.

Confinement Effects of Two-dimensional Surfaces on Water Adsorption and Dissociation over Pt(111).

It has been established that the confined space created by stacking a two dimensional (2D) surface atop a metal catalyst serves as a nano-reactor. According to recent research, when a graphene (Gr) overlayer encloses a Pt catalyst from above, the activation barrier for the water dissociation reaction, a process with major industrial significance, decreases. In order to investigate how the effect of confinement varies among different two-dimensional (2D) materials, we study the adsorption and dissociation barriers of water molecule on Pt(111) under graphene, hexagonal boron nitride (h-BN), and heptazine-based graphitic carbon nitride (g-C3N4) layers using density functional theory calculations. Our findings reveal that the strength of adsorption does not decrease consistently with a reduction in the height of the 2D overlayer. Furthermore, a smaller barrier is not always the consequence of poorer adsorption of the reactant. We also examine the effect of confinement on the shape of the reaction path, on the frequencies of vibrational modes, and on the rate constants derived using the harmonic transition state theory. Overall, all three of the 2D surfaces cause a decrease in barrier height and a weakening of adsorption, though to differing degrees due to a mix of mechanical, geometric and electronic variables.

Feasibility study on the heat transfer enhancement of gap flow induced by wasted vibration of linear compressor body

Refrigerators account for 20–30 % of household electricity consumption, with the compressor contributing to 80 % of the total consumption. Therefore, it is essential to increase the compressor efficiency. One approach to enhance compressor performance involves increasing heat dissipation to lower the temperature of the suction system and boost the refrigerant density entering the suction chamber. To achieve that innovatively, we harnessed the waste vibration of the linear compressor body to create a gap flow between the body and the housing, enhancing compressor performance by augmenting heat dissipation. Measurements of gap flow temperature, cylinder surface temperature, and heat flux on the cylinder surface were conducted, varying the RPM, gap size, and the shape of the gap flow path. We also observed variations in the gap flow rate with RPM and stroke. The results revealed that gap temperature and heat flux increased with higher RPM and smaller gap size, and the application of ribs to the gap flow path proved to be more effective in enhancing temperature and heat flux. Additionally, it is anticipated that heat flux will further increase with a longer stroke as the flow rate increases. Therefore, to optimize heat dissipation through gap flow using the waste vibration of the compressor body, it is advantageous to employ a smaller gap size, higher RPM, longer stroke, and apply ribs to the gap flow path. Future research should focus on verifying the effectiveness of increased heat dissipation and improved Energy Efficiency Ratio (EER) through actual compressor experiments.

A Revised Abaqus® Procedure for Fracture Path Simulation Based on the Material Effort Criterion.

This paper presents the results of computer simulations of fracture in three laboratory tests: the three-point bending of a notched beam cut from sandstone, the pull-out test of a self-undercutting anchor fixed in sandstone, and the pull-out test of a bar embedded in concrete. Five material failure criteria were used: Rankine, Coulomb-Mohr, Drucker-Prager, Ottosen-Podgórski, and Hoek-Brown. These criteria were implemented in the Abaqus® FEA system to work with the crack propagation modeling method-extended finite element method (X-FEM). All criteria yielded similar force-displacement relationships and similar crack path shapes. The improved procedure gives significantly better, close-to-real crack propagation paths than can be obtained using the standard subroutines built into the Abaqus® system.

Study of the payload extraction trajectory heavy class carrier rocket

Relevance. As the weight and complexity of the payload that needs to be launched into orbit increases, the relevance of rational trajectory selection to ensure maximum efficiency and minimum costs for delivering the payload to a given orbit increases. Rational choice of the trajectory of a heavy-class launch vehicle has a number of important practical applications. Firstly, it allows you to increase the payload capacity of the launch vehicle and reduce the cost of delivering payload to the target orbit. This is especially important in the context of the development of the space industry, when more and more companies and organizations are showing interest in launching their own satellites and other spacecraft in conditions of fierce economic competition. Choosing a rational trajectory for launching a payload into orbit will significantly reduce the cost of launches and make them available to a wider range of potential customers. Secondly, the choice of launch vehicle trajectory parameters is important for ensuring safety and minimizing risks during spacecraft launches. Thanks to the rational choice of trajectory, it is possible to reduce adverse impacts on the environment and eliminate the possibility of emergency situations associated with loss of control over the flight of the launch vehicle. Rational selection of launch vehicle trajectory parameters is a complex task that requires comprehensive research and consideration of various factors, such as aerodynamic parameters of the atmosphere, mass and characteristics of the payload (spacecraft), engine operating parameters, characteristics of the target orbit, features of the launch of the launch vehicle and many other factors. A more thorough and systematic study of the influence of these parameters will significantly improve the efficiency and reliability of launching spacecraft into orbit. Thus, the choice of rational parameters for the launch vehicle trajectory is a relevant and important topic for scientific research. Increasing the rocket's payload capacity, reducing the cost of delivering a spacecraft to a given orbit, and ensuring launch safety are tasks that depend on the chosen shape and parameters of the rocket's trajectory. Such research has important practical significance and can become the basis for the development of new technologies and methods in the space industry. The purpose of the study is to study and select rational parameters for the trajectory of a heavy-class launch vehicle when launching a payload. The main task is to determine the flight path parameters that will allow achieving maximum efficiency and accuracy in delivering the payload to a given orbit. To achieve the goal of the study, an analysis of various factors influencing the launch parameters of the spacecraft is required, such as the structural and aerodynamic characteristics of the rocket, the influence of aerodynamic factors and the Earth’s gravitational field on the flight path. Taking these factors into account, numerical calculations were carried out on the basis of a system of differential equations of motion using a computer program created in the MAPLE software package. Based on calculations, modeling of the shape and parameters of the launch vehicle flight path was carried out. Research results. During the study, the rational parameters of the trajectory of a heavy-class launch vehicle were selected. Calculations were carried out using numerical modeling of the parameters of payload launch trajectories, and an analysis of the resulting trajectories was carried out. Minimizing the rocket's flight time was identified as the main criterion for the rational choice of trajectory, which allows increasing launch efficiency and saving energy resources. An increase in payload mass and minimization of fuel consumption were adopted as additional criteria. Conclusion. The procedure for choosing rational parameters for the trajectory of a heavy-class launch vehicle proposed in this work will improve the delivery accuracy and reliability of spacecraft launches at the stage of ballistic analysis when designing rockets. The results of the study have practical significance for the development of future heavy-duty launch vehicle missions and improving the efficiency of space launches.

Drag-Mitigating Dynamic Flight Path Design and Sensitivity Analysis for an Ultra-Long Tether Underwater Kite

Abstract This paper presents a computational study of an underwater kite operating in environments requiring tethers exceeding a kilometer in length, referred to herein as ultralong tether (ULT) applications. Leveraging a detailed dynamic model of the kite and tether, we study the relationship between path shape and tether drag at varying tether lengths in order to develop meaningful insights as to the operation of systems that require ultralong tethers in order to reach viable flow resources. An initial study of a ULT kite application operating in a uniform flow field is presented, demonstrating that with an appropriately designed flight path, the kite is able to suppress the motion of the majority of the tether in order to achieve an order of magnitude greater power output than can be achieved with a straight tether, which is the typical assumption used in a performance estimation. Tether drag mitigation is characterized through the use of a novel metric termed effective tether length, which characterizes the total length of tether engaged in drag production. It is shown that a high-performance path shape can reduce the effect of tether drag by over 50%. This performance is shown to be comparable to the multi-airborne wind energy system (MAWES) proposed by Leuthold et al. (2017, “Induction in Optimal Control of Multiple-Kite Airborne Wind Energy Systems,” IFAC-PapersOnLine, 50(1), pp. 153–158; 2018, “Operational Regions of a Multi-Kite Awe System,” 2018 European Control Conference (ECC), IEEE, Limassol, Cyprus, June 13–15, pp. 52–57), which suppresses tether motion through mechanical design rather than merely though careful path selection and control. This initial study in a uniform flow field is followed by two sensitivity studies: one that assesses performance in realistic environments where the flow magnitude is a function of altitude above the seabed and a second that assesses the impact of tether drag reduction techniques. It will be shown that by careful selection of path shape, site, and tether design, a single kite in a ULT marine application can achieve performance rivaling that of the MAWES without the extra required mechanical complexity.

Characterization of the migration of organic contaminants in laboratory-scale groundwater polluted by underground coal gasification.

Underground coal gasification (UCG) is a promising technology, but the groundwater pollution caused by UCG is a potential risk to the environment. The measured results of the stratum in the combustion cavity resulting from UCG had proven that the combustion cavity would be filled with some UCG residues and caving rocks when UCG was finished. The pollutants in underground water around the combustion cavity include organic pollutants, inorganic pollutants, and ammonia nitrogen, and one of the primary organic pollutants is phenol. The migration and diffusion characteristics of organic pollutants (taking phenol as a representative) in the groundwater of the combustion cavity were investigated by breakthrough experiments and numerical simulations. The results show that the hydraulic conductivity of the coarse UCG residues is much higher than that of fine residues, and the hydraulic conductivity of the UCG residues with the size of - 0.15 mm and 0.15-0.3 mm are 4.68 × 10-6 m/s and 1.91 × 10-4 m/s respectively. The dispersivity λ for the migration of organic pollutants will be influenced significantly by the size of UCG residues in fractures of the combustion cavity, while the distribution coefficient Kd will not. The dispersivity of organic pollutants in the fine UCG residues is more significant than that in the coarse residues, and the λ for the two kinds of residues are 3.868 cm and 1.765 cm, respectively. The shape of the migration path slightly affects the pollutant concentration distribution along the path, but the width of a path has a more pronounced influence on the concentration distribution. In this research, the influence was formulated by a new technical term, MPWIT, which is related to transverse dispersion. Specifically, while the transverse dispersion values account for 20% and 10% of the longitudinal dispersion, respectively, the corresponding MPWIT values are 39.48 mm and 33.96 mm.

Optimal path shape of friction-based Track-Nonlinear Energy Sinks to minimize lifecycle costs of buildings subjected to ground accelerations

Track Nonlinear Energy Sinks (T-NES) are Pendulum Tuned Mass Dampers (PTMDs) whose nonlinear restoring forces are obtained from curved path shapes. They combine the abilities of traditional spring-based NESs with the operational advantages of PTMDs. T-NES can resonate with broad frequency content, becoming effective even under damage to the host structure originating from strong ground motions. In the published literature, the integration of Friction Dampers (FDs) into T-NESs (so-called T-NES Type II) has only been studied on PTMDs with circular tracks, and in deterministic settings. Herein, a novel Reliability-Based Design Optimization (RBDO) procedure is presented to find the optimal track shape of T-NES Type II in buildings subjected to earthquakes. The objective is to minimize expected life-cycle damage costs corresponding to slight damage, moderate damage, and extensive damage limit states. A set of rational functions encompassing a wide range of generic curvatures is constructed to describe the T-NES track shape. The nonlinear description is used for restoring force and also in the dissipative mechanism. The case study is a medium-rise building located in Chile. The results indicate that, for the studied building, the optimal path is multimodal, and quite different track profiles can significantly reduce oscillation of the host structure.

Tactile cues compensate for unbalanced vestibular cues during progression on inclined surfaces

A previous study demonstrated that rodents on an inclined square platform traveled straight vertically or horizontally and avoided diagonal travel. Through behavior they aligned their head with the horizontal plane, acquiring similar bilateral vestibular cues – a basic requirement for spatial orientation and a salient feature of animals in motion. This behavior had previously been shown to be conspicuous in Tristram's jirds. Here, therefore jirds were challenged by testing their travel behavior on a circular arena inclined at 0°-75°. Our hypothesis was that if, as typical to rodents, the jirds would follow the curved arena wall, they would need to display a compensating mechanism to enable traveling in such a path shape, which involves a tilted frontal head axis and unbalanced bilateral vestibular cues. We found that with the increase in inclination, the jirds remained more in the lower section of the arena (geotaxis). When tested on the steep inclinations, however, their travel away from the arena wall was strictly straight up or down, in contrast to the curved paths that followed the circular arena wall. We suggest that traveling along a circular path while maintaining contact with the wall (thigmotaxis), provided tactile information that compensated for the unbalanced bilateral vestibular cues present when traveling along such curved inclined paths. In the latter case, the frontal plane of the head was in a diagonal posture in relation to gravity, a posture that was avoided when traveling away from the wall.

Real-Time Vehicle and Lane Detection using Modified OverFeat CNN: A Comprehensive Study on Robustness and Performance in Autonomous Driving

This examination researches the use of profound learning methods, explicitly utilizing Convolutional Brain Organizations (CNNs), for ongoing recognition of vehicles and path limits in roadway driving situations. The study investigates the performance of a modified Over Feat CNN architecture by making use of a comprehensive dataset that includes annotated frames captured by a variety of sensors, including cameras, LIDAR, radar, and GPS. The framework shows heartiness in identifying vehicles and anticipating path shapes in 3D while accomplishing functional rates of north of 10 Hz on different GPU setups. Vehicle bounding box predictions with high accuracy, resistance to occlusions, and efficient lane boundary identification are key findings. Quiet, the exploration underlines the likely materialness of this framework in the space of independent driving, introducing a promising road for future improvements in this field.

Reliability-based optimization of supported pendulum TMDs’ nonlinear track shape using Padé approximants

Supported Pendulum Tuned Mass Dampers (PTMDs) are vibration absorbers whose mass is constrained to oscillate along a curved path, enabling to use gravity as a restoring force. Through a proper track shape selection, they can adapt to the so-called Nonlinear Energy Sinks (NES) concept, consolidated for spring–mass–damper TMDs. Accordingly, NESs are recognized for their ability to resonate in a wide range of frequencies due to their nonlinear nature, becoming more effective when variations on the host structure’s natural frequencies occur. However, regardless of the recent advances in the last few years, gaps remain to be explored in the track shape optimization of supported PTMDs. For instance, a comprehensive literature review shows that Reliability-Based Design Optimization (RBDO) studies to determine the track shape of supported PTMDs cannot be found to the best of the author’s knowledge. Within this context, this paper proposes an original RBDO approach to define the track shape of supported PTMDs in buildings subjected to seismic excitation. For this purpose, a generic rational function with an arbitrary curvature, determined from the Padé approximation of the circle equation, is constructed to allow the PTMD’s path shape search. This procedure allows optimizing fewer parameters than required in Taylor series expansions while providing a wider range of alternatives for numerical optimization. Finally, an active-learning Kriging-based Efficient Global Optimization (EGO) procedure is employed to find the optimum solutions with few objective function evaluations. The application case consists of a typical soft story building subjected to seismic loadings. The optimal track differs from the circle equation, with a higher slope for moderate displacements.

Terrain-Shape-Adaptive Coverage Path Planning With Traversability Analysis

Coverage path planning (CPP) is in great demand with applications in agriculture, mining, manufacturing, etc. Most research in this area focused on 2D CPP problems solving the coverage problem with irregular 2D maps. Comparatively, CPP on uneven terrains is not fully solved. When there are many slopy areas in the working field, it is necessary to adjust the path shape and make it adapt to the 3D terrain surface to save energy consumption. This article proposes a terrain-shape-adaptive CPP method with three significant features. First, the paths grow by themselves according to the local terrain surface shapes. Second, the growth rule utilizes the 3D terrain traversability analysis, which makes them automatically avoid entering hazardous zones. Third, the irregularly distributed paths are connected under an optimal sequence with an improved genetic algorithm. As a result, the method can provide an autonomously growing terrain-adaptive coverage path with high energy efficiency and coverage rate compared to previous research works. It is demonstrated on various maps and is proven to be robust to terrain conditions.

Integrated optimization method for transonic turbine based on direct free-form deformation and prescreening differential evolutionary optimizer

With the increased load of turbine stages, shock waves and secondary flow influence the performance of turbines more and more significantly. Aiming at improving the aerodynamic efficiency of transonic turbines, an integrated aerodynamic optimization platform for turbines has been established. The aerodynamic shape of the flow path and blades is simultaneously parametrized by a directly manipulated free-form deformation (DFFD) method, and the optimization is conducted via a data-driven differential evolutionary algorithm. Furthermore, a prescreening strategy is introduced to enhance the convergence speed of the optimizer. The TTM-stage is selected as the research object. The result shows that the turbine isentropic efficiency at the design point increases from 90.45 % to 91.94 % after optimization. The main reasons for aerodynamic performance enhancement are the weakening of shock waves and the reduction of separation regions. As a comparison, another two optimization cases are carried out. One optimizes the blades individually with the same methods and configurations, and the other optimizes the blades and flow path simultaneously without the prescreening strategy. The optimized isentropic efficiency in the latter two cases is 91.31 % and 90.92 %, whichis 0.63 % and 1.02 % lower than the first optimization result, respectively. This shows the effectiveness of the proposed optimization method for turbine performance improvement.

Incremental shape measurement with fiber Bragg gratings in a multi-core fiber for three-dimensional paths.

A multi-core fiber (MCF) provides a compact solution for three-dimensional (3D) shape measurement. In this Letter, an incremental shape measurement method for 3D paths is proposed, using an MCF based on fiber Bragg gratings (FBGs). A few FBG sets can iteratively provide plenty of strain information about the 3D path during navigation. The overall continuities of the curvature and torsion are improved based on intensive strain calculations. Meanwhile, the transformation matrix algorithm is used to reconstruct the shape of 3D paths. Dynamic measurement experiments of a seven-core fiber with two FBG sets are carried out to verify the incremental shape measurement method. This method shows a great performance of the different paths, with a maximum incremental position error of 4.68%.

Investigation of manufacturing deviations of CPC scaffolds for improving the design process

Abstract In current implantology, calcium phosphate cement (CPC) is increasingly used. A special focus is given to CPC scaffolds, as they are suitable for cell settlement and growth due to their positive osteoconductive properties. The design of the scaffolds is of decisive importance for this. The value ranges of the geometric parameters of these scaffolds (e.g. path distance, path diameter), which are positive for both cell settlement and cell growth, are very small. Manufacturing deviations therefore have a significant impact on cell settlement and growth. The pasty manufacturing consistency can cause sagging at the path interstices of a layer immediately below, resulting in significant manufacturing deviations. A larger path distance and thus a larger path interstitial space promotes cell settlement, but at the same time increases the risk of CPC path shape inconsistency. This in turn can have a negative effect on cell settlement. Therefore, the aim of this paper is to investigate the discrepancies between the nominal and actual state at a path distance favourable to cell settlement on the basis of manufactured CPC scaffolds. In this context, geometric and manufacturing parameters of the shape deviation are to be identified and constructive design adaptations are to be derived on the basis of these. In addition, the effects of the shape and position deviations on the flow behaviour will be investigated.

Model of Surface Texture for Honed Gear Considering Motion Path and Geometrical Shape of Abrasive Particle

Gear power-honing is mainly applied to finish small and medium-sized automotive gears, especially in new energy vehicles. The distinctive curved surface texture greatly improves the noise emission and service life of honed gears. The surface texture for honed gear considering the motion path and geometrical shape of abrasive particles has not been investigated. In this paper, the kinematics of the gear honing process is analyzed, and the machining marks produced by the abrasive particles of honing wheel scratching abrasive particles against the workpiece gear are calculated. The tooth surface roughness is modeled considering abrasive particle shapes and material plastic pile-ups. This results in a mathematical model that characterizes the structure of the tooth surface and the orientation of the machining marks. Experiments were used to verify the model, with a maximum relative error of less than 10% when abrasive particles are spherical. Based on this model, the effects of process parameters on the speeds of discrete points on the tooth flank, orientations of machining marks and roughness are discussed. The results show that the shaft angle between the workpiece gear and the honing wheel and the speed of the honing wheel is the main process parameters affecting the surface texture. This research proposes a surface texture model for honed gear, which can provide a theoretical basis for optimizing process parameters for gear power-honing.

Study on the formation mechanism of functional surface microstructure by ultrasonic vibration assisted laser processing

In this paper, a novel ultrasonic vibration-assisted laser surface processing technology is proposed for preparing microstructures on metal surfaces. Firstly, the formation mechanism of single laser spot on metal surface is analyzed, and the mathematical model of three-dimensional morphology of single crater is derived, the influence of ultrasonic vibration on the crater morphology is studied. Secondly, the influence of ultrasonic vibration on the position distribution of heat affected zone in single laser path is studied. After, the influence of ultrasonic vibration and laser scanning speed on the shape of the laser path is expressed by pushing the overlap rate between the heat affected zones. The calculation results show that the larger ultrasonic amplitude, the greater effect on the curve shape. Finally, the correctness of the calculation and simulation results is verified by experiments. It is observed that ultrasonic vibration can promote the discharge of the melt and provide a new method for changing the surface microstructures.

One-component fermion plasma on a sphere at finite temperature: the anisotropy of the path conformations

In our previous work (Fantoni 2018 Int. J. Mod. Phys. C 29 1850064) we studied, through a computer experiment, a one-component fermion plasma on a sphere at finite, non-zero temperature. We extracted thermodynamic properties, such as the kinetic and internal energy per particle, and structural properties, such as the radial distribution function, and produced some snapshots of the paths to study their shapes. Here, we revisit this study, giving more theoretical details explaining the path shape anisotropic conformation due to the inhomogeneity in the polar angle of the variance of the random walk diffusion from the kinetic action.

A new inclining flight mode and oblique takeoff technique for a tiltrotor aircraft

A new tiltrotor inclining flight mode is presented in the study. Based on this mode, an optimized tiltrotor oblique takeoff technique is designed to improve the flight performance and efficiency in tiltrotor's takeoff operation. First, the proposed inclining flight mode is built through the dynamics analysis of the tiltrotor and related maneuver design and that makes the tiltrotor able to fly along an oblique path with its body line parallel to the flying direction. Then, with this new mode, a tiltrotor oblique takeoff technique and related control program are devised. Third, the shape of takeoff path in the oblique takeoff operation is studied, and an optimized oblique curved path is introduced to further improve the tiltrotor flight performance and efficiency. Simulations are conducted to investigate the effectiveness of the designed inclining flight mode and implemented oblique takeoff procedure in a set of different takeoff paths. It is found that the tiltrotor's flight performance and efficiency are significantly improved in terms of both required takeoff time and energy consumption. Finally, flight tests corresponding to the simulation work are conducted, that prove the effectiveness of the newly designed inclining flight mode and oblique takeoff technique.