Speed Behavior Research Articles

Accessing and manipulating dispersive shock waves in a nonlinear and nonlocal Rydberg medium

Dispersive shock waves (DSWs) are fascinating wave phenomena occurring in media when nonlinearity overwhelms dispersion (or diffraction). Creating DSWs with low generation power and realizing their active controls is desirable but remains a longstanding challenge. Here, we propose a scheme to generate weak-light DSWs and realize their manipulations in an atomic gas involving strongly interacting Rydberg states under the condition of electromagnetically induced transparency (EIT). We show that for a two-dimensional (2D) Rydberg gas a weak nonlocality of optical Kerr nonlinearity can significantly change the edge speed of DSWs and induces a singular behavior of the edge speed and hence an instability of the DSWs. However, by increasing the degree of the Kerr nonlocality, the singular behavior of the edge speed and the instability of the DSWs can be suppressed. We also show that in a 3D Rydberg gas, DSWs can be created and propagate stably when the system works in the intermediate nonlocality regime. Due to the EIT effect and the giant nonlocal Kerr nonlinearity contributed by the Rydberg-Rydberg interaction, DSWs found here have extremely low generation power. In addition, an active control of DSWs can be realized; in particular, they can be stored and retrieved with high efficiency and fidelity through switching off and on a control laser field. The results reported here are useful not only for unveiling intriguing physics of DSWs but also for finding promising applications of nonlinear and nonlocal Rydberg media.

Geometry Optimization of Speed Humps Based on Ride Comfort and Driving-Safety-Based Assessment

The present study investigates the speed behaviors of drivers encountering speed humps on urban and suburban roads. The purpose is to optimize the geometric dimensions of different types of speed hump by considering ride comfort and driving safety criteria. Field observations of drivers’ behavior were conducted near 90 speed humps in eight cities in Mazandaran Province, Iran. Vehicles speed modeling was carried out using multi-layer perception and normalized radial basis functions artificial networks. The sensitivity analysis results of artificial neural network (ANN) models showed different factors associated with speed humps’ performance. While the length of entrance and exit ramps and passage width were the most influential factors in urban roads, speed before the humps’ position plays a crucial factor in suburban roads. Finally, the optimum geometry of speed humps was presented by ANN models for different types of roads.

Weather Conditions and Telematics Panel Data in Monthly Motor Insurance Claim Frequency Models

Risk analysis in motor insurance aims to identify factors that increase the frequency of accidents. Telematics data is used to measure behavioural information of drivers. Contextual variables include temperature, rain, wind and traffic conditions that are external to the driver, but may also influence the probability of having an accident, as well as vehicle and personal characteristics. This paper uses a monthly panel data structure and the Poisson model to predict the expected frequency of claims over time. Some meteorological information is included. Two types of claims are considered separately: only those related to at-fault third-party liability accidents, and all types of claims including assistance on the road. A sample of drivers in Spain in 2018–2019 is analysed with information on claiming frequency per month. Drivers were observed for seven months. Our analysis is novel because monthly summaries of telematics information are combined with weather data in a panel structure, revealing that external factors affect the expected claims frequencies. Reckless speeding behaviours and intense urban circulation increase the risk of an accident, which also increases with windy conditions.

Modeling over speeding behavior of vehicles using a random parameter negative binomial approach: A case study of Mumbai, India

Over speeding is one of the most common factors contributing to road accidents leading to traffic-related injuries and deaths. Understanding determinants of over speeding behavior is an important step toward enhancing road safety and developing robust intervention strategies. Moreover, there is a need to extend this knowledge with respect to developing countries, where there is a significant variation in the operating speeds of the vehicles owing to the heterogeneous traffic conditions. The present study captured the speeding behavior of the vehicles in Mumbai, India, during the years 2017 and 2018 using roadside observational surveys along with the spatial and temporal attributes of the selected locations. This study investigates the combined effect of temporal and spatial attributes on the over speeding frequency. A random parameter negative binomial model is developed utilizing the observational data to explain the over speeding behavior of the vehicles at the selected count locations. The developed model accounts for unobserved heterogeneity across the over speeding count locations based on temporal, road geometric, and built environment attributes. The study results confirm the presence of heterogeneity in the over speeding behavior of the vehicles at the count locations. In terms of policy implications, results suggest that temporary speed calming strategies could be adopted during the non-peak hours and on weekends. Similarly, deploying speed humps, rumble strips, or adopting law enforcement strategies can circumvent over speeding behavior on arterial roads. Lastly, developing well-connected roads with frequent presence of intersections and traffic signals can be another strategy applicable for such behavior.

Correlating 3D printing performance with sol-gel transition based on thermo-responsive k-carrageenan affected by fructose

Thermo-responsive food inks occupy an important part of 3D food printing materials. A great challenge of their accurate 3D printing is to ensure sol-gel transition is adapted to 3D printing process. In this study, k -carrageenan (KG) incorporated with fructose (0–30%, w/v) was selected as a representation of thermo-responsive inks, and their interactive mechanism was investigated. Sol-gel transition and rheology were correlated with 3D printing process in terms of extrusion stage, formation stage, and self-supporting stage. Results indicated that fructose addition increased ink's gelation temperature (Tg) and affected printing temperature selection. During extrusion stage, ink in sol-state with a low viscosity was desirable to enable proper extrudability. While, during formation stage, sol-gel transition speed (gelation time) was important for extruded ink to solidify to avoid continuous spreading. Increased elastic modulus (G′) with fructose addition was beneficial for printed structures to be self-supportable during self-supporting stage. Low field nuclear magnetic resonance (LF-NMR) indicated that water mobility was increasingly restricted with addition of fructose. Hydrogen bond, hydrophobic and electrostatic interactions all significantly affected the KG/fructose ink. Scanning electron microscopy (SEM) suggested that fructose addition resulted in a denser network structure. This study would provide insights on 3D printing of thermo-responsive food inks by correlating with sol-gel transition. • 3D printing behavior was correlated with sol-gel transition process. • 3D printing was divided into three stages and correlated with rheology change. • Fructose addition increased Tg, gelation speed and resultant 3D printing behavior.

Which visual cues do drivers use to anticipate and slow down in freeway curve approach? An eye-tracking, think-aloud on-road study

Although much research is done on speed and gaze behaviour inside curves, there is little understanding of which cues drivers use to anticipate and slow down while approaching curves. Therefore, an on road experiment was conducted in which 31 participants drove through six freeway curves in their own car. During the experiment, look-ahead fixations and speed were recorded using an eye-tracker and a GPS tracker, respectively. In addition to these measurements, the participants verbalised their reasons for changing speed. The distribution of fixations over various areas of interest was investigated around the start of deceleration before each curve and around the start of each curve. Verbalisation data were analysed to infer the number and types of reasons for changing speed and when these were mentioned together with mentions of deceleration before a curve. The results showed that before starting to decelerate, the participants fixated mostly on the Focus of Expansion and edges parallel to the curve trajectory, whereas most fixations on warning or speed signs were recorded mostly after participants started to decelerate. These findings suggest that drivers use information from the Focus of Expansion, be it a change in optical flow or the presence of a kink in the alignment, as the main cue to start decelerating. Parallel edges are also important cues, whereas warning and speed signs are primarily used to confirm that a speed change is needed.

How Do Cognitive Interventions Impact Driver Aggressiveness in China?—A Driving Simulator Study

Aggressive driving behavior is one of the main reasons for traffic crashes in China. However, how cognitive interventions affect impulsive driving behavior is still unknown. In this study, a simulated drive was constructed to evaluate the influence of different cognitive interventions. In addition to speeding behavior in limit zones, speed when passing pedestrians, at intersections, and on the whole drive was adopted as a measure to evaluate aggressive driving behaviors. Forty-eight young drivers were recruited with monetary rewards. Compared to the control group, the penalty feedback intervention significantly reduced the mean speed in the 40 km/h zone, the 80 km/h zone, and when passing pedestrians. The combined feedback intervention significantly reduced the distance ratio of speeding in the 40 km/h and 80 km/h zones, as well as the mean speed at the intersection and on the whole drive. However, the interaction effects between the driving task and intervention method were not remarkably observed during aggressive driving behaviors. The findings from this study provide evidence that different cognitive interventions contribute distinctively to improving aggressive driving behaviors. These conclusive results have possible implications for the design of vehicle warning systems and traffic safety interventions.

A Comparison of Contributing Factors between Young and Old Riders of Motorcycle Crash Severity on Local Roads

This study aims to identify the factors that influence the severity of motorcycle crashes on local roads, particularly given the high speeds often observed for motorcycles on these roads with low traffic volumes and numerous multi-leg intersections. Previous research has shown that a rider’s age can impact their speed behavior. To explore this issue, data on motorcycle crashes from 2015 to 2020 in Thailand—a middle-income developing country—were analyzed using a random parameter logit model with unobserved heterogeneity in means and variances, comparing young (<30-year-old) and older (>50-year-old) riders. The contributing factors were divided into four groups: driver, crash, environmental, and road factors. The transferability test yielded different results for the young rider and old rider models, indicating that it is appropriate to analyze these models separately. A constant value revealed that old riders were more likely to die in a crash than young riders. In terms of the random parameter, the local address and road surface variables were found to be significant in both models. The results of unobserved heterogeneity in means and variances identified significant variables in both models, including gender, exceeding the speed limit, lit roads, unlit roads, mobile phone use, and road surface. These findings were used to develop policy recommendations for reducing the severity of motorcycle crashes on local roads.

Adapting V ISA Technology: Driver Behaviour along Interchange Ramp and Merging/Diverging Terminals

An original in vehicle Intelligent Speed Adaptation System for Visibility (V-ISA) was designed to promote compliance with real-time speed management. The functionality of V-ISA is based on the prevailing sight conditions along the road, and operates in two variants: (i) providing visual information, and (ii) vehicle speed intervention. A road scenario with the driver performing merging and diverging manoeuvres in a motorway section was designed. A within-subject experiment involved 32 participants and a vehicle equipped with the two variants and the system off (baseline condition) under two traffic flow conditions. V ISA had a significant positive effect on the drivers’ longitudinal performance along ramps. This change in behaviour along ramps had no effect on merging and diverging manoeuvres. V ISA had a positive impact on driver speed behaviour in such complex road environment and assisted drivers to modulate the operating speed towards the safe dynamic limits.

Crash harm before and during the COVID-19 pandemic: Evidence for spatial heterogeneity in Tennessee

Major concerns have been raised about road safety during the COVID-19 pandemic in the US, as the crash fatalities have increased, despite the substantial reduction in traffic. However, a comprehensive analysis of safety–critical events on roadways based on a broader set of traffic safety metrics and their correlates is needed. In addition to fatalities, this study uses changes in total crashes and total monetary harm as additional measures of safety. A comprehensive and unique time-series database of crashes and socio-economic variables is created at the county level in Tennessee. Statistics show that while fatal crashes increase by 8.2%, total crashes decrease by 15.3%, and the total harm cost is lower by about $1.76 billion during COVID-19 (2020) compared with pre-COVID-19 conditions (2019). Several models, including generalized least squares linear, Poisson, and geographically weighted regression models using the differences between 2020 and 2019 values, are estimated to rigorously quantify the correlates of fatalities, crashes, and crash harm. The results indicate that compared to the pre-pandemic periods, fatal crashes that occurred during the pandemic are associated with more speeding & reckless behaviors and varied across jurisdictions. Fatal crashes are more likely to happen on interstates and dark-not-lighted roads and involve commercial trucks. These same factors largely contribute to crash harm. In addition, a greater number of long trips per person not staying home during COVID-19 is found to be associated with more crashes and crash harm. These results can inform policymaking to strengthen traffic law enforcement through appropriate countermeasures, such as the placement of warning signs and the reduction of the speed limit in hotspots.

Kaahaajat: Finnish Attitudes towards Speeding.

People driving in excess of the posted speed limit (referred to as speeding in English or Kaahaajat in Finnish) is a common road user behaviour. In Finland, between 2000 and 2020, speeding was identified as the key contributing factor in 41% of fatal motor vehicle collisions. This may be because disregarding speed limits on motorways and on residential roads are the most common violations performed by Finnish drivers. This study identifies factors influencing speeding while driving in Finland. In particular, 703 responses from Finnish drivers of the ESRA2 (E-Survey of Road users' Attitudes) were analysed to understand the theory of planned behaviour (TPB) factors underpinning speeding behaviours in three road environments: inside built-up areas; outside of built-up areas; and on motorways and freeways. Three binary logistic regression analyses were used to understand which elements of TPB were associated with self-reported speeding in each of these environments. Approximately two thirds of participants reported speeding in each of the three road environments. Attitudes and subjective norms were associated with speeding in built-up areas and on motorways or freeways. In addition, perceived behavioural control and age were significantly associated with speeding outside of built-up areas. The findings highlight how a systematic approach is needed to address speeding considering enforcement, engineering, legislation, and education.

How psychological factors affect speeding behavior: Analysis based on an extended theory of planned behavior in a Chinese sample

Speeding, the most frequent traffic offense, is a key contributor to road crashes. This study explores the psychological factors affecting drivers’ speeding behavior (exceeding the posted speed limit by more than 10%) based on the extended theory of planned behavior (TPB). The scale incorporating TPB constructs and additional variables (Type A personality, risk perception, and driving habit) was developed to collect empirical data, and 945 valid samples were obtained. The reliability and validity of the developed scales were verified, and a structural equation model of drivers’ speeding behavior was established to explore the causal relationship between speeding behavior and psychological characteristics and the interrelationships between TPB variables (speeding intention, attitude, subjective norm, and perceived behavioral control), explicit cognition predictors (risk perception and Type A personality) and implicit habitual factors (driving habit). The results showed that speeding intention and driving habit positively correlated with self-reported speeding behavior. In addition, attitude and risk perception positively correlated with speeding intention. Although Type A personality trait had no significant effects on speeding behaviors, it had significant effects on attitude and risk perception. In addition, the results of the mediation analysis demonstrated that speeding intention, driving habit, and attitude toward speeding are the most influential factors. Attitude and risk perception have a significant indirect effect on speeding behavior mediated by speeding intention. Drivers’ attitudes, driving habits, and risk perception played a mediating role in the relationships between Type A personality traits and speeding behavior. The findings yield insights into useful information and directions for designing road safety interventions, developing driver education and training programs, and strengthening social messaging aimed at the general public.

Drivers’ Speeding Behavior in Residential Streets: A Structural Equation Modeling Approach

Speeding in residential areas is a rampant high-risk driving behavior that occurs worldwide. This study investigated the intention and behavior of speeding in residential streets (with a speed limit of 30 km/h) in Iran based on the Theory of extended Planned Behavior (TPB). A total of 480 participants filled out the TPB-based questionnaire online. Nine different factors were identified by exploratory factor analysis. The interrelationship of these factors, as well as their connection with speeding intention and behavior, was analyzed using the Structural Equation Modeling (SEM) method. The results suggested that the adoption of the extended TPB framework to identify factors related to speeding in residential areas was effective in predicting speeding intention and behavior. Affective attitude, descriptive and personal norms, perceived behavioral control, habits, and specification of residential streets were direct predictors of speeding intention. The intention was also strongly associated with speeding behavior in residential areas, serving as the only factor that directly predicts speeding behavior. The two factors of specification and facilities were also significantly related to speeding behavior on residential streets. The results of this study can have positive implications for preventing and reducing crashes on residential streets.

Speed of sound and liquid-gas phase transition in nuclear matter

We investigate the speed of sound in nuclear matter at finite temperature and density (chemical potential) in the nonlinear Walecka model. The numerical results suggest that the behaviors of sound speed are closely related to the the nuclear liquid-gas (LG) phase transition and the associated spinodal structure. The adiabatic sound speed is nonzero at the critical endpoint (CEP) in the mean-field approximation. We further derive the boundary of vanishing sound velocity in the temperature-density phase diagram, and point out the region where the sound wave equation is broken. The distinction between the speed of sound in nuclear matter and that in quark matter contains important information about the equation of state of strongly interacting matter at intermediate and high density. We also formulate the relations between differently defined speeds of sound using the fundamental thermodynamic relations.

The Introduction of an MR-Conditional Prototype for Cardiopulmonary Bypass Support: Technical Aspects and System Requirements

Introduction: The use of cardiopulmonary bypass (CBP; also known as a heart-lung machine) in newborns with complex congenital heart defects may result in brain damage. Magnetic resonance imaging (MRI) assessments cannot be performed safely because the metal components used to construct CBP devices may elicit adverse effects on patients when they are placed in a magnetic field. Thus, this project aimed to develop a prototype MR-conditional circulatory support system that could be used to perform cerebral perfusion studies in animal models. Methods: The circulatory support device includes a roller pump with two rollers. The ferromagnetic and most of the metal components of the roller pump were modified or replaced, and the drive was exchanged by an air-pressure motor. All materials used to develop the prototype device were tested in the magnetic field according to the American Society for Testing and Materials (ASTM) Standard F2503-13. The technical performance parameters, including runtime/durability as well as achievable speed and pulsation behavior, were evaluated and compared to standard requirements. The behavior of the prototype device was compared with a commercially available pump. Results: The MRI-conditional pump system produced no image artifacts and could be safely operated in the presence of the magnetic field. The system exhibited minor performance-related differences when compared to a standard CPB pump; feature testing revealed that the prototype meets the requirements (i.e., operability, controllability, and flow range) needed to proceed with the planned animal studies. Conclusion: This MR-conditional prototype is suitable to perform an open-heart surgery in an animal model to assess brain perfusion in an MR environment.

Prevalence, precision, and road safety implications of using faulty speedometers among commercial drivers in Ghana

ABSTRACT Vehicular speed is a significant risk factor for road crashes globally. The first objective was to establish the proportion of motorists who drive with faulty speedometers. Second, the study sought to establish procedures used to determine speeds when speedometers are defective. The third objective was to establish the precision with which motorists determine driving speeds with faulty speedometers. Convenience sampling was used to interview 124 professional drivers at 16 bus terminals in Kumasi to understand their speeding behaviors and perceptions on the accuracy of using defective speedometers. Secondly, drivers using defective speedometers were purposively nested for real-life driving tests in which their self-reported speeds were concurrently compared with actual speed measurements made with android-speedometers. Results show that 58% of drivers used defective speedometers. Ninety-six percentof the drivers with defective speedometers were confident that they could precisely tell their travelling speeds through procedures such as driving experiences, personal judgment, intruding wind, engine sound, and poking hands outside cars, thereby underestimating their actual speeds. In the driving tests, mean self-reported speed (58.7 ± 5.2 km/h) was significantly lower than measured speed (64.6 ± 8.9 km/h; p = 0.0003). This research has implications for road safety enforcement, education, and advocacy.

Evaluating Driver Response to an Advanced Speed Display near Uncontrolled Median Openings

Uncontrolled median openings contribute to more road crashes because drivers do not obey traffic laws such as driving between lanes and following speed limits. This study examined the effectiveness of the different types of signs near an uncontrolled median opening in Mahmoud Abad, Iran. There were Signs 1 and 2 with a single message, while Signs 3 and 4 contained multi-messages. An Internet of Things (IoT) test system was developed to collect and record vehicle speed data before and after each sign installation. Results showed that speeding behavior decreased almost immediately after the road signs were installed and remained almost constant until the beginning of uncontrolled median openings. Moreover, multi-message traffic signs reduce vehicle speeds twice as much as single-message signs. Additionally, only multi-message signs are effective at reducing speed limit violations.

STUDY OF THE BEARING FRICTION INSIDE ON A MOBILE COUPLING JOINT

The mobile couplings are used in movement and torque transmission between two main shafts usually and have a wide application in transportation and machining systems. These mobile coupling must undertake the shafts misalignments that could appear, usually in the transversal plane and in the longitudinal plane. The friction which appears in coupling’s joints between the involved parts has an important influence on their dynamic behaviour, wear and lifetime. A solution to reduce the friction inside the mobile coupling is to place bearings in joints. The paper presents some general aspects on mobile tripod couplings and following this, using the inside relative movement in joints between parts and corresponding adequate bearing, the friction coefficient is studied. There are considered two cases for the studied radial ball bearings: a sealed one and a non-sealed one. The measurements are accomplished by using a tribometer for different radial loadings and rotational speeds of the inner ring of the bearings. In the final part of the paper, the results present the exploitation conditions of the bearings which assure small frictional loses. According to the obtained results, in order to gain small frictional loses, the mobile tripod coupling with external contacts are suitable to be used in the case of high loads, with small influences on the frictional behaviour of the rotational speeds.

Stochastic adaptive-service level agreement-based energy management model for smart grid and prosumers.

The growing issue of demand-supply management between the prosumers and the local energy market requires an efficient and reliable energy management model. The microlayers, such as prosumers, energy districts, and macro players, namely retail dealers and wholesale dealers play a pivotal role in achieving mutual benefits. The stochastic nature of renewable energy generation in energy districts requires an effective model that can contemplate all stochastic complexities. Therefore, this paper proposes a mutual trade model between energy districts and smart grid to authorize the prosumers for mutual energy transactions under the stochastic adaptive-service level agreement. Moreover, multiple smart contacts are developed between the stakeholders to design adaptability and stochastic behavior of wind speed and solar irradiance. The real-time adaptations of the stochastic adaptive-service level agreement are based on technical beneficial feasibility and achieved through stochastic and adaptive functions. The optimized solution based on a genetic algorithm is proposed for the energy cost and energy surplus of prosumers and output parameters of the mutual trade model (grid revenue). In the context of mutual benefits associated with balanced demand and supply, the economic load dispatch and simplex method maximization are used for optimized demand-supply energy management. Moreover, the effectiveness of the proposed adaptive and stochastic mutual trade model is validated through simulation and statistical analysis.

Design of Intelligent Ultrasonic Guided Vehicle

Due to the requirement of the development of the times, all walks of life require more and more intelligence, so more and more intelligent mobile machines and equipment are popularized. Compared with traditional equipment, smart cars have better mobility, safety and practicality. However, nowadays, domestic follow-up equipment generally exists in various highly specialized venue environments, which have certain environmental requirements, or track following camera cars in other specific sites, which have certain environmental requirements. There is no follow-up equipment or personal products for public places with complex situations, such as supermarkets, airports, railway stations, etc. This paper designs an intelligent vehicle based on Arduino programming, which is simple and practical, highly modular and highly portable. The smart car with low design cost, simple and mature technology and high portability can be used in work and ordinary life without manual operation. The smart car can use Arduino Nano, acoustic distance measurement module, motor, etc. in this design to achieve the positioning of specific targets and calculate the distance, including forward and backward, turning, At the same time, according to the feedback information, we can adjust the speed and turn behavior to track the target. Using mature ultrasonic ranging technology, chip, accurate positioning control algorithm, this simple, cheap and practical intelligent tracking car is designed