Instantaneous Acceleration Research Articles

Accuracy of a local positioning system for time-series speed and acceleration and performance indicators in game sports

ABSTRACT The objective was to determine the reliability and validity of a local positioning system (LPS) promising high accuracy at reduced product costs. Fifty-five random static positions in a gym (54.8 × 26.0 m) were obtained 10 times via LPS (50 Hz) and measuring tape. An athlete’s LPS-derived peak and time-series speed and acceleration during dynamic movements (n = 80) were compared with Vicon (100 Hz). Reliability and validity were assessed via Intraclass and Concordance Correlation Coefficients (ICC/CCC), root mean square errors, Bland-Altman plots, and analysis of variance. ICC3,1 (≥0.999) and CCC (0.387–0.999) were calculated for static positions (errors <0.22 m). CCC for time-series speed and acceleration, and peak speed, acceleration, and deceleration were 0.884–0.902, 0.777–0.854, 0.923, 0.486, and 0.731, respectively. Errors were larger in time-series acceleration (14.37 ± 3.77%) than in speed (11.99 ± 5.78%) ( = 0.472, p < 0.001) and in peak acceleration (28.04 ± 14.34%) and deceleration (25.07 ± 14.90%) than in speed (7.34 ± 6.07%) ( = 0.091, p < 0.01). LPS achieved excellent reliability and moderate-to-excellent validity of time-series speed and acceleration. The system accurately measured peak speed but not peak acceleration and deceleration. The system is suitable for analyses based on instantaneous speed and acceleration in game sports (e.g., energy estimations).

Hybrid Propulsion for Motorcycle Application to Reduce Engine-out Emissions: An Analytical-Experimental Investigation

All over the world, motorcycles represent an important share of motorized vehicles helping to meet daily urban transport needs, thus, particularly in urban contexts, two-wheelers impact to air pollution is significant. In a previous experimental investigation, emissions of regulated pollutants were measured in the exhaust of a four-stroke motorcycle belonging to the Euro-3 legislative category. Since exhaust emissions and fuel consumption are very sensitive to variations in vehicles instantaneous speed and acceleration, such experimental results are used in this research to recognize the kinematic parameters that cause higher CO and HC emissions. The hybrid electric propulsion is then proposed to reduce exhaust emissions in particular driving conditions which include high levels of acceleration with resultant sudden steep increase in engine speed. In such phases, in fact, an enrichment of the air/fuel mixture is needed which affects the catalyst conversion efficiency. Subsequently, the power requirements and the grade of electrical assistance in such driving situations are estimated by a procedure based on both the measured exhaust emissions and the kinematic parameters that characterize the driving dynamics collected during the experimental tests. Finally, the share of CO and HC emissions that could be saved utilizing a hybrid motorcycle instead of a conventional thermal motorcycle is calculated through an environmental analysis.

EV Simulation Tests in Various Road Conditions

Electric vehicles are gaining popularity all the time. As a result, they have become the subject of much research. The purpose of this work is to analyze the energy consumption of the vehicle depending on the specificity of the designated routes. For this purpose, three routes with different types of traffic have been designated. Then, the research test vehicle, together with the necessary equipment, made runs on the indicated roads. This made it possible to record the basic parameters related to the movement, such as: instantaneous velocity, acceleration, travel time and route length. Based on the collected data, simulation tests were carried out in the AVL Cruise program. The obtained results show the parameters related to energy consumption on each route. The amount of input and output energy from the battery, energy consumption per 1 km of the route and the course of changes in the battery current or changes in the battery charge status were determined. The conducted research allowed to obtain specific conclusions and propose further research directions.

The observable properties of cool winds from galaxies, AGN, and star clusters – II. 3D models for the multiphase wind of M82

ABSTRACT Galactic winds are a crucial player in galaxy formation and evolution, but observations of them have proven extraordinarily difficult to interpret, leaving large uncertainties even in basic quantities such as mass outflow rates. Here we present an analysis of the wind of the nearby dwarf starburst galaxy M82 using a semi-analytic model that is able to take advantage of the full three-dimensional information present in position–position–velocity data cubes measured in the H i 21-cm line, the CO J = 2 → 1 line, and the Hα line. Our best-fitting model produces position-dependent spectra in good agreement with the observations, and shows that the total wind mass flux in the atomic and molecular phases is ≈10 M⊙ yr−1 (corresponding to a mass loading factor of ≈2–3), with less than a factor of 2 uncertainty; the mass flux in the warm ionized phase is more poorly constrained, and may be comparable to or smaller than this. At least over the few kpc off the plane for which we trace the outflow, it appears to be a wind escaping the galaxy, rather than a fountain that falls back. Our fits require that clouds of cool gas entrained into the wind expand only modestly, suggesting they are confined by magnetic fields, radiative cooling, or a combination of both. Finally, we demonstrate that attempts to model the wind using simplifying assumptions such as instantaneous acceleration and a constant terminal wind speed can yield significantly erroneous results.

Modelling Vehicle Emissions and Fuel Consumption Based on Instantaneous Speed and Acceleration Levels

Modelling Vehicle Emissions and Fuel Consumption Based on Instantaneous Speed and Acceleration Levels

Pedestrians’ Microscopic Walking Dynamics in Single-File Movement: The Influence of Gender

Demographics of individuals could largely influence their behaviors and interactions with surrounding pedestrians. This study investigates the influence of pedestrians’ gender on microscopic walking dynamics of single-file movements using the trajectory data collected from a controlled experiment conducted under different density levels. Instantaneous acceleration (with a time lag that varied from 0.12 s to 0.68 s) versus relative speed between the subject pedestrian and the pedestrian in front of him/her plots displayed significant correlations, which is analogous to the car following behavior, indicating that the relative speed is a key determinant of pedestrians’ acceleration behavior. Time-delayed instantaneous accelerations and decelerations of pedestrians were modeled as functions of relative speed and spacing that are used in microscopic behavior models and gender using multiple linear regression. The outcomes revealed that in addition to relative speed, gender has a significant influence on instantaneous acceleration and deceleration for all density levels. Spacing displayed significant influence on acceleration and deceleration only for several density levels, and that influence was not as strong as relative speed. Males were likely to accelerate more and decelerate more compared to females for all density levels. The findings of this study provide important insights into gender dependence on microscopic walking dynamics. Furthermore, the results emphasize the importance of considering gender influence in microscopic behavior models.

A New Method for Validating and Generating Vehicle Trajectories From Stationary Video Cameras

Image processing based vehicle tracking is a powerful tool for monitoring traffic, but it is error prone. Relatively small errors that impede measuring time-series speed and acceleration can be hard to detect, e.g., 1 m positioning error in a 100 m long trajectory. This paper presents an efficient approach to separate the positioning errors from vehicle travel for evaluating image processing based vehicle trajectories. The approach starts with a spatiotemporal slice, STS, which is effectively a visual time-space diagram sampled from the video. This work skews the STS to flatten a given trajectory, eliminating the vehicle travel recorded in the trajectory. Positioning errors that were imperceptible relative to the distance traveled become readily apparent in the flattened track. Thus, providing a means to quickly assess reported trajectories from almost any image processing system against the true vehicle positions in the original video data. Recognizing that the flattening process works both ways, if errors are evident in a given trajectory, the STS method can also be used to quickly fix them. Thereby providing a path to accurate instantaneous speed and acceleration throughout the given trajectory. Alternatively, one can use this process to generate vehicle trajectories directly from the STS. While the main focus is longitudinal tracking, the process can also be used to assess (extract) the lateral position of a given vehicle. The method is evaluated using the NGSIM, Cityflow and UA-DETRAC datasets, in each case it is shown how this work can increase the fidelity of the given dataset.

Hybrid Propulsion in SI Engines for New Generation Motorcycles: A Numerical-Experimental Approach to Assess Power Requirements and Emission Performance

Worldwide mopeds and motorcycles are taking on a growing main role in private mobility with a direct impact on air pollution, particularly in urban contexts of many Asian and European countries. In a preceding experimental investigation, HC and CO emissions were measured in the exhaust of a last-generation motorcycle belonging to the Euro-3 legislative category. Since exhaust emissions and fuel consumption are very sensitive to variations in vehicles instantaneous speed and acceleration, in this research new experimental results are used to recognize the kinematic parameters that cause higher engine-out emissions. In this paper, the hybrid electric propulsion is proposed for motorcycle application to reduce exhaust emissions in particular driving conditions which include high levels of acceleration with resultant rapid steep increase in engine speed. In such operating conditions, an enrichment of the air/fuel mixture is required, which affects the catalyst conversion efficiency. Subsequently, the power requirements and the grade of electrical assistance in such driving situations are calculated by a procedure based on both the measured exhaust emissions and the kinematic parameters of the driving dynamics collected during the experimental tests. Lastly, the share of CO and HC emissions that could be saved utilizing a hybrid motorcycle instead of a conventional thermal motorcycle is estimated through a specific environmental analysis.

A high-accuracy initial alignment method based on backtracking process for strapdown inertial navigation system

When the alignment time is short, the traditional initial alignment method of strapdown inertial navigation system has very low accuracy, and even the attitude angle error is difficult to converge. We propose a high-accuracy initial alignment method for strapdown inertial navigation system based on the backtracking process, which reuses short-time measurement data to improve the accuracy and speed of initial alignment. We introduce the backtracking process into coarse alignment and fine alignment of strapdown inertial navigation system. In the coarse alignment, the instantaneous acceleration error caused by the backtracking process is estimated and compensated. In the fine alignment, the optimal initialization method of the parameters in the Kalman filter is given. The initial alignment experimental results of strapdown inertial navigation system prove the effectiveness of the proposed method. Compared with the previous initial alignment method, the accuracy and speed of the proposed method are improved.

Analysis of the Running Ability Mining Model of Football Trainers Based on Dynamic Incremental Clustering Algorithm.

Fast-running ability is a very important basic quality of football players. However, players are dynamic. It is difficult for coaches to grasp the running speed, instantaneous acceleration, and other indicators of small athletes in real time with the naked eye. Therefore, to accurately test the performance of athletes in fast-running ability, this paper studies the running ability mining model of football coaches based on the dynamic incremental clustering algorithm. According to scientific procedures and methods, the evaluation model and standard of running ability of Chinese elite female football players are established. The effectiveness of the model is 0.83, as verified by the standard recognition method, which shows that the evaluation model is efficient. The research considers the denoising of the original data. The model has rich data and standard test methods and procedures. It can be used as a measure of the running ability of China's elite female football players in a certain period and range. The research solves the problem of the insufficient running ability of domestic football players. It provides an important reference for training the next generation of excellent national football players.

Research on the Influence of Multiple Parameters on the Responses of a B-type Subway Train

To obtain improved comprehensive crashworthiness criteria for a B-type subway train, the influence laws of the vehicle design collision weight M and empty stroke D on the train’s collision responses were investigated, and multi-objective optimization and decision-making were performed to minimize TS (total compression displacement along the moving train) and TAMA (the overall mean acceleration along the moving train). Firstly, a one-dimensional train collision dynamics model was established and verified by comparing with the results of the finite element model. Secondly, based on the dynamics model, the influence laws of M and D on the collision responses, such as the energy-absorbing devices’ displacements and absorbed energy, vehicles’ velocity and acceleration, TS, TAMA and the coupling correlation effect were investigated. Then, surrogate models for TS and TAMA were developed using the optimal Latin hypercube method (OLHD) and response surface method (RSM), and multi-objective optimization was conducted using the particle swarm optimization algorithm method (MPOSO). Finally, the entropy method was used to obtain the weight coefficients for TS and TAMA, and multi-objective decision-making was performed. The results indicate that D and M significantly affect the compression displacements and energy absorption of the first three collision interfaces, but have limited impact on the last three collision interfaces. The velocity versus time curves of vehicle M1 and M2 are shifted and parallel with different D. However, the velocity versus time curves of all the vehicles are shifted but gradually divergent with different M. The maximum collision instantaneous accelerations of the vehicles are directly determined by M, but are only slightly affected by D. Under the coupling effect, all concerned collision responses are strongly correlated with M; however, the responses are weakly correlated with D except for the compression displacement at the M2-M3 collision interface and the maximum collision instantaneous acceleration of vehicle M2. The comprehensive crashworthiness criteria of the B-type subway train were significantly improved after multi-objective optimization and decision-making. The research provides more theoretical and engineering application references for the subway train crashworthiness design.

Tongue and Lip Acceleration as a Measure of Speech Decline in Amyotrophic Lateral Sclerosis

Purpose: The goal of this study was to examine the efficacy of acceleration-based articulatory measures in characterizing the decline in speech motor control due to amyotrophic lateral sclerosis (ALS). Method: Electromagnetic articulography was used to record tongue and lip movements during the production of 20 phrases. Data were collected from 50 individuals diagnosed with ALS. Articulatory kinematic variability was measured using the spatiotemporal index of both instantaneous acceleration and speed signals. Linear regression models were used to analyze the relationship between variability measures and intelligible speaking rate (a clinical measure of disease progression). A machine learning algorithm (support vector regression, SVR) was used to assess whether acceleration or speed features (e.g., mean, median, maximum) showed better performance at predicting speech severity in patients with ALS. Results: As intelligible speaking rate declined, the variability of acceleration of tongue and lip movement patterns significantly increased (p < 0.001). The variability of speed and vertical displacement did not significantly predict speech performance measures. Additionally, based on R² and root mean square error (RMSE) values, the SVR model was able to predict speech severity more accurately from acceleration features (R² = 0.601, RMSE = 38.453) and displacement features (R² = 0.218, RMSE = 52.700) than from speed features (R² = 0.554, RMSE = 40.772). Conclusion: Results from these models highlight differences in speech motor control in participants with ALS. The variability in acceleration of tongue and lip movements increases as speech performance declines, potentially reflecting physiological deviations due to the progression of ALS. Our findings suggest that acceleration is a more sensitive indicator of speech deterioration due to ALS than displacement and speed and may contribute to improved algorithm designs for monitoring disease progression from speech signals.

Calculation Method of the Blasting Throwing Energy and Its Variation Affected by the Burden

Precise control of casting velocity and effective throwing kinetic energy conversion efficiency in blasting engineering are challenges. To provide a theoretical basis and reference for the implementation plan and fine construction of the cast blasting project, we study the problems of casting velocity and energy consumption ratio of broken rock under the impact load of explosions in this manuscript. The calculation methods of casting velocity and throwing energy of broken rock under two blasting modes of spherical charge and cylindrical charge are established by using the theory of dimensional analysis and rock breaking by blasting. A large number of model tests are carried out by using high-speed photography. The results indicate that the casting velocity of broken rock after explosive initiation has two evident stages: instantaneous acceleration to a certain value and subsequent fluctuation; the velocity presents an ordinary distribution law with the step height, and the fitting correlation of high-speed photography results is more than 91%. With the minimum burden increasing from 0.12 m to 0.2 m, the energy consumption decreases from 1306.88 J to 747.49 J and the proportion of energy consumption decreases from 14.77% to 8.45%.

Capturing High Resolution Plant Movement in the Field.

Lodging of small grains due to environmental stresses results in yield loss, quality reduction, and difficulties with mechanical harvesting, which lead to economic consequences. New technological discoveries allow for faster and in situ measurements for determining the mechanics of loading stress and plant movement. The overall measurement of plant movement can be a very sophisticated method to mechanically test and predict the behavior of stems when exposed to wind. We investigated the inertial measurement of plants during different magnitude wind events. This type of analysis captures real time quantitative stem behavior during wind events. Using a 1.5 cm2 inertial measurement sensor attached to the upper panicle of a plant, we recorded the ranges and extremes of instantaneous linear acceleration and rotational velocity. When this technology was applied to historically known varieties of different lodging classification, the measurements were able to distinguish between cereal species and differences between movement of lodging susceptible and resistant plants without physical lodging. This type of technology could be used to improve field based lodging models and quantify movement resulting from micro changes in structural and composition of the stem, and to analyze plant movement in natural conditions with a resolution and specificity that has so far been prohibitively expensive and technologically challenging to achieve.

Spectral walls at one loop

A spectral wall is a surface in a moduli space of classically BPS solitons where an internal excitation crosses the continuum mass threshold. It has recently been shown that spectral walls in classical field theory repel solitons whose corresponding internal excitations are excited. We investigate, for the first time, the fate of spectral walls in a quantum theory, calculating the instantaneous acceleration of a wave packet of classically BPS antikinks in the presence of an impurity. We find that, in the quantum theory, the antikinks are repelled even when the bound mode is not excited. Perhaps due to this repulsive force, the dramatic classical effects of the spectral wall are not seen in our quantum calculation.

Benchmarking the driver acceleration impact on vehicle energy consumption and CO2 emissions.

The study proposes a methodology for quantifying the impact of real-world heterogeneous driving behavior on vehicle energy consumption, linking instantaneous acceleration heterogeneity and CO2 emissions. Data recorded from 20 different drivers under real driving are benchmarked against the Worldwide Harmonized Light Vehicle Test Cycle (WLTC), first by correlating the speed cycle with individual driver behavior and then by quantifying the CO2 emissions and consumption. The vehicle-Independent Driving Style metric (IDS) is used to quantify acceleration dynamicity, introducing driving style stochasticity by means of probability distribution functions. Results show that the WLTC cycle assumes a relatively smooth acceleration style compared to the observed ones. The method successfully associates acceleration dynamicity to CO2 emissions. We observe a 5% difference in the CO2 emissions between the most favourable and the least favourable case. The intra-driver variance reached 3%, while the inter-driver variance is below 2%. The approach can be used for quantifying the driving style induced emissions divergence.

Transient mathematical prediction and experimental verification of the charging characteristics of subsea accumulators

This study is focused on the charging characteristics of the subsea accumulators used to provide power for safety on a subsea well. The charging time and storage volume are strictly limited according to API specification for a subsea accumulator system. Long hydraulic lines must be used to cope with the depth of seawater, which will significantly increase the charging time and cause a large pressure drop. In addition, the pressure in hydraulic pump and subsea accumulators used also varies with charging. A transient flow will occur during the charging of the system. In this paper, a systematic transient mathematical model (STMM) of the subsea accumulator charge system is established. The STMM includes three main parts: the air driven liquid pump, the long hydraulic pipeline, and the subsea accumulator. A double-coefficient unsteady friction model based on instantaneous acceleration is applied in the long pipeline model. The Redlich–Kwong real gas state equation is used to calculate the gas in the accumulator. A series of charging experiments for two rated working pressure of 10,000 psi and 15,000 psi on the ground were carried out. The results of the experiment showed very consistently with those of the STMM. The liquid pressure in the accumulator is divided into three stages during charging: rapidly increasing stage, slowly increasing stage, and maintaining constant stage. Moreover, an engineering proposal was presented to reduce the design pressure requirements of the system. Furthermore, the charging time will increase significantly as the length of the pipe increases, but decreases as the inner diameter of the pipe increases. The paper outlines a direction for the design theory and engineering practice of the subsea accumulator charge system.

Estimation of traffic emissions in a polycentric urban city based on a macroscopic approach

This paper presents a macroscopic dynamic modeling framework for road traffic emissions in an urban city that has numerous central business districts (CBDs). The framework combines a two-dimensional (2D) continuum dynamic traffic assignment (DTA) model that captures macroscopic features of traffic flow and a microscopic instantaneous emission model associated with the instantaneous speed and acceleration of traffic flow. A heterogeneous traveling population continuously distributed in space is classified according to the trip destinations chosen by travelers. Each copy of flow tends to select an optimal route with the minimum cost to destination by means of instantaneous traffic information. For each copy of flow, an unstructured finite volume method as well as a fast sweeping method is designed to solve the proposed model. In order to validate the feasibility of the model and algorithm, a case study is conducted as an example to study the macroscopic characteristics of traffic flow and predict traffic-related pollutants like NOx, VOC, CO2 and PM in urban areas.

Superluminal light group velocity in tapered optical microfibers

Superluminal light group velocity was formerly reported in anomalous dispersion, nonlinear amplification of light pulse, high-gain lasers' cavities, and waveguides. Motivated by a recent observation of light acceleration in optical microfiber [1], the possibility of attaining the light group velocity exceeds its value in vacuum is investigated. The investigation of superluminal velocity is in tapered optical microfiber that has a radius decreases with propagation axis by a factor 10-3. Our results show the possibility of attaining superluminal group velocity in this microfiber at length of about 1080µm. At this length the instantaneous acceleration of light is found to be 13×1019 m/s2 which its corresponding Unruh temperature is 0.527K.

Superior Electromagnetic Shielding and Mechanical Buffering Achieved by Alternating Conductive and Porous Supramolecular Networks

The development of electromagnetic interference (EMI) shielding materials with excellent EMI shielding effectiveness (SE), and superior mechanical performance is of great importance in daily life and in the military, where they are used for intelligent transportation systems and ammunition. Generally, shielding performances can be realized via reflection loss and absorption loss. However, it is still a challenge to enhance these two kinds of electromagnetic wave loss in the same material at the same time to achieve ideal shielding performance. Herein, a flexible Ag NDs/CNT@PC/Ni‐9 film composed of five conductive layers and four porous layers is prepared by alternating Ag NDs/CNT layers and PC/Ni layers through self‐assembly. The obtained film with a thickness of 890 μm exhibits a remarkable SE performance of 138 dB in the X‐band. Additionally, with a series of continuous volcanic mechanical impacts (&gt;10 000 g), the maximum instantaneous acceleration is decreased by 30.02% due to the buffering of the film, which constitutes a much‐improved energy absorption cushion relative to that of traditional buffering materials, such as foam metal and rubber. A material integrated with strong EMI shielding and high mechanical shock resistance is designed, which provides an effective strategy for the development of functional materials for extreme environments.