Journal articles on the topic 'Hard-braking'
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Hunter, Margaret, Enrique Saldivar-Carranza, Jairaj Desai, Jijo K. Mathew, Howell Li, and Darcy M. Bullock. "A Proactive Approach to Evaluating Intersection Safety Using Hard-Braking Data." Journal of Big Data Analytics in Transportation 3, no. 2 (April 3, 2021): 81–94. http://dx.doi.org/10.1007/s42421-021-00039-y.
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AbstractTypical safety improvements at signalized intersections are identified and prioritized using crash data over 3–5 years. Enhanced probe data that provides date, time, heading, and location of hard-braking events has recently become available to agencies. In a typical month, over six million hard-braking events are logged in the state of Indiana. This study compared rear-end crash data over a period of 4.5 years at 8 signalized intersections with weekday hard-braking data from July 2019. Using Spearman’s rank-order correlation, results indicated a strong correlation between hard-braking events and rear-end crashes occurring more than 400 ft upstream of an intersection. The paper concludes that using a month or two of hard-braking events occurring upstream from the stop bar may be a useful tool to screen potential locations with elevated rear-end crashes. Using these techniques described in this paper, new commercially available hard-braking data sources will provide an opportunity for agencies to follow up with mitigation measures addressing emerging problems much quicker than typical practices that rely on 3–5 years of crash data.
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Ju, Jiawei, Aberham Genetu Feleke, Longxi Luo, and Xinan Fan. "Recognition of Drivers’ Hard and Soft Braking Intentions Based on Hybrid Brain-Computer Interfaces." Cyborg and Bionic Systems 2022 (July 20, 2022): 1–13. http://dx.doi.org/10.34133/2022/9847652.
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In this paper, we propose simultaneous and sequential hybrid brain-computer interfaces (hBCIs) that incorporate electroencephalography (EEG) and electromyography (EMG) signals to classify drivers’ hard braking, soft braking, and normal driving intentions to better assist driving for the first time. The simultaneous hBCIs adopt a feature-level fusion strategy (hBCI-FL) and classifier-level fusion strategies (hBCIs-CL). The sequential hBCIs include the hBCI-SE1, where EEG signals are prioritized to detect hard braking, and hBCI-SE2, where EMG signals are prioritized to detect hard braking. Experimental results show that the proposed hBCI-SE1 with spectral features and the one-vs-rest classification strategy performs best with an average system accuracy of 96.37% among hBCIs. This work is valuable for developing human-centric intelligent assistant driving systems to improve driving safety and driving comfort and promote the application of BCIs.
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Roberts, Roland G. "Braking Bad: Stopping Translation in Hard Times." PLoS Biology 12, no. 5 (May 20, 2014): e1001867. http://dx.doi.org/10.1371/journal.pbio.1001867.
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Xue, Yuqing, Stanford Chihuri, Howard F. Andrews, Marian E. Betz, Carolyn DiGuiseppi, David W. Eby, Linda L. Hill, et al. "Potentially Inappropriate Medication Use and Hard Braking Events in Older Drivers." Geriatrics 6, no. 1 (February 20, 2021): 20. http://dx.doi.org/10.3390/geriatrics6010020.
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Potentially inappropriate medications (PIMs) identified by the American Geriatrics Society should generally be avoided by older adults because of ineffectiveness or excess risk of adverse effects. Few studies have examined the effects of PIMs on driving safety measured by prospectively and objectively collected driving data. Data for this study came from the Longitudinal Research on Aging Drivers study, a multisite naturalistic driving study of older adults. Multivariable negative binominal modeling was used to estimate incidence rate ratios and 95% confidence intervals of hard braking events (proxies for unsafe driving behavior defined as events with a deceleration rate ≥0.4 g) associated with PIM use among older drivers. The study sample consisted of 2932 drivers aged 65–79 years at baseline, including 542 (18.5%) who used at least one PIM. These drivers were followed through an in-vehicle recording device for up to 44 months. The overall incidence of hard braking events was 1.16 per 1000 miles. Use of PIMs was associated with a 10% increased risk of hard braking events. Compared to drivers who were not using PIMs, the risk of hard braking events increased 6% for those using one PIM, and 24% for those using two or more PIMs. Use of PIMs by older adult drivers is associated in a dose-response fashion with elevated risks of hard braking events. Reducing PIM use in older adults might help improve driving safety as well as health outcomes.
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Abdul Majid, M. M., S. A. Abu Bakar, S. Mansor, M. K. Abdul Hamid, and N. H. Ismail. "Modelling and PID Value Search for Antilock Braking System (ABS) of a Passenger Vehicle." Journal of the Society of Automotive Engineers Malaysia 1, no. 3 (April 28, 2021): 228–36. http://dx.doi.org/10.56381/jsaem.v1i3.57.
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This paper presents the methodologies use in determining the PID value of an Antilock Brake System (ABS) of a Malaysian made passenger vehicle. The research work involves experimental work for data acquisitions, development of braking model, parameter tuning for both simulation model parameter and PID values search. A Malaysian made car is equipped with instrumentation used to collect vehicle behaviour during normal and hard braking manoeuvres. The data collected are the vehicle’s stopping distance and longitudinal speed. The data during the normal braking are used to validate a two degree of freedom (2 DOF) of vehicle’s braking model, while the data collected during the hard braking are used to search for the PID value used to control the operation of the ABS system. The developed simulation model of a braking system correlates well with the experimental data and the tuning done on the PID algorithm indicates that the ABS is controlled by the PI system.
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Ohgi, Yuji, Chikara Miyaji, and Kazutoshi Kobayashi. "An Analysis of Hard Braking of a Bicycle." Journal of Japan Society of Sports Industry 5, no. 2 (1995): 35–44. http://dx.doi.org/10.5997/sposun.5.2_35.
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Liu, Difei, Stanford Chihuri, Thelma Mielenz, Linda Hill, Carolyn DiGuiseppi, David Strogatz, and Guohua Li. "DIABETES MELLITUS AND HARD BRAKING EVENTS IN OLDER DRIVERS." Innovation in Aging 6, Supplement_1 (November 1, 2022): 754. http://dx.doi.org/10.1093/geroni/igac059.2738.
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Abstract There are an estimated 37 million people with diabetes mellitus (DM) in the United States, including 16 million older adults. DM can impair patients’ driving safety due to diabetic peripheral neuropathy, hypoglycemia, or hyperglycemia, and eye diseases. However, few studies have examined the association between DM and driving safety based on naturalistic driving data. Data for this study came from the Longitudinal Research on Aging Drivers (LongROAD) project, a multisite naturalistic driving study of 2990 drivers aged 65–79 years at baseline. Driving data for the study participants were recorded by in-vehicle recording devices for up to 44 months. We used multivariable negative binomial modeling to estimate the incidence rate ratios (IRRs) and 95% confidence intervals (CIs) of hard braking events (i.e., proxies for unsafe driving behavior defined as maneuvers with deceleration rates ≥ 0.4 g) associated with DM. Of the 2856 study participants eligible for this study, 482 (16.9%) reported having DM at baseline. The overall incidence rate of hard braking events was 1.16 per 1000 miles. Adjusted for age, race/ethnicity, marital status, education level, annual household income, urbanicity, history of stroke, and number of medications, drivers with DM had a 10% increased rate of hard braking events compared to drivers without DM (adjusted IRR 1.10; 95% CI: 1.08, 1.12). Results of this study indicates that DM is associated with a significantly increased rate of hard braking events in older drivers, suggesting less safe driving. Driving safety should be incorporated into DM management and care programs.
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Murugan, N., C. Sagong, A. S. Cuamatzi Castelan, K. Moss, T. Roth, C. L. Drake, and P. Cheng. "0203 To and From the Night Shift: Risky On-the-Road Driving in Night Shift Workers." Sleep 43, Supplement_1 (April 2020): A79—A80. http://dx.doi.org/10.1093/sleep/zsaa056.201.
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Abstract Introduction Drowsy driving is a common occupational hazard for night shift workers (NSWs). While sleep loss is commonly identified as the primary culprit of drowsy driving, another critical factor to consider is circadian phase. However, the role of circadian phase in driving safety has not been well characterized in NSWs. This study examined if dim light melatonin offset (DLMOff, i.e. the cessation of melatonin secretion) is also a relevant phase marker of susceptibility to four different subtypes of risky on-the-road driving behaviors. Methods On-the-road driving was monitored over 8 weeks via a mobile application that tracked risky driving behaviors using accelerometer and GPS data from cell phones (N=15; 3052 total driving events recorded). Risky driving behaviors included: 1) frequency of hard-braking events, 2) frequency of aggressive-acceleration events, 3) duration of excessive-speeding, and 4) duration of phone-usage. At week 2, participants spent 24 hours in-lab where hourly saliva samples were collected and assayed for melatonin, and DLMOff was calculated. Phase angle of driving events relative to DLMOff was used as the predictor in nested mixed-effects regressions, with risky driving behaviors as the outcome variables. Results The most common occurrences of risky driving were phone-usage and hard-braking. On average, NSWs had 46.7% and 42.0% of driving events with at least one occurrence of phone-usage and hard-braking, respectively. Rates of aggressive-acceleration and speeding were 24.4% and 20.4%. Positive phase angles (i.e. driving after DLMOff) were associated with reduced rates of hard-braking and aggressive-acceleration, but not of phone-usage and excessive-speeding. Specifically, rates of hard-braking and aggressive-acceleration decreased by 4.5% (p<.01) and 3.4% (p=.05) every two hours following DLMOff, respectively. Conclusion The study suggests DLMOff appears to be an important variable for predicting accident risk in NSWs. If replicated, circadian phase should be considered in recommendations to increase occupational health and safety of NSWs. Support Support for this study was provided to PC by NHLBI (K23HL138166).
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Lee, Suzanne E., Sarah B. Brown, Miguel A. Perez, Zachary R. Doerzaph, and Vicki L. Neale. "Normal and Hard Braking Behavior at Stop Signs and Traffic Signals." Proceedings of the Human Factors and Ergonomics Society Annual Meeting 49, no. 22 (September 2005): 1897–901. http://dx.doi.org/10.1177/154193120504902203.
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A testbed intersection violation warning system was developed to address the problem of intersection crashes. The effectiveness of such systems is fundamentally dependent on the driver-braking model used to decide if a warning should be issued to the driver. If the model is unrealistic, drivers can either be annoyed due to assumed braking levels that are too low, or can be warned too late if braking expectations are too high. Initial algorithm development relied on data from the Collision Avoidance Metrics Partnership (CAMP) Forward Collision Warning (FCW) project. However, it was unknown whether the CAMP data (collected in the presence of stopped lead vehicles) would be applicable to the intersection problem (e.g., will drivers respond similarly to red traffic signals and stopped lead vehicles). Braking profile and performance tests were thus conducted to determine the applicability of the CAMP FCW results to the intersection violation warning.
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Koylu, Hakan, and Ali Cinar. "Development of control algorithm for ABS–suspension integration to reduce rotational acceleration oscillations of wheel." Transactions of the Institute of Measurement and Control 40, no. 3 (November 13, 2016): 1018–34. http://dx.doi.org/10.1177/0142331216677318.
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In this study, we aimed to obtain smoother wheel rotational acceleration during braking with an activated anti-lock brake system (ABS). This produces effective and easily controlled rotational acceleration of a wheel by an ABS control unit. For this, the wheel load is changed by considering the interaction between the brake pressure change rates and rotational acceleration of the wheel. This is provided by means of the control strategy developed in this study. The rules of the control strategy are based on ABS test results. These tests are conducted with soft, medium-hard and hard dampers on wet and slippery road surfaces. Therefore, the control strategy changes the wheel load by setting the damper stage according to agreement between brake pressure and wheel rotational acceleration. Here, the control strategy constantly applies the damping force of the damper providing the shortest braking distance under wet or slippery road conditions. All results show that the control strategy considerably improves wheel rotational acceleration oscillations during braking with an activated ABS.
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Fu, Long Fei, Yu Ren Li, Guang Lai Tian, Bo Liang, and Hong Ling Wang. "Slid Mode VSC for Aircraft Anti-Skid Braking System with Index Reaching Law." Applied Mechanics and Materials 336-338 (July 2013): 973–77. http://dx.doi.org/10.4028/www.scientific.net/amm.336-338.973.
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Aircraft anti-skid braking system providing protection for the safety of the aircraft landed by controlling the brake pressure to be maintained slip ratio in best condition. The aircraft anti-skid braking system is hard to control as the nonlinear model of the aircraft dynamics, the uncertainty of friction between the tires and the ground of braking process. With the study of slip ratio and research of aircraft anti-skid braking system dynamics model, the sliding mode variable structure controller is designed. Then index reaching law is adopted to eliminate the system chattering and the performance is analyzed, further more the robustness is strengthen. Simulation results indicate that: the slip ratio follows the optimum slip ratio, the input signal is smooth, achieve the purpose.
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Malvezzi, M., P. Presciani, B. Allotta, and P. Toni. "Probabilistic analysis of braking performance in railways." Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit 217, no. 3 (May 1, 2003): 149–65. http://dx.doi.org/10.1243/095440903769012867.
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To increase safety and efficiency in the management of railway traffic, a new speed control system, named SCMT, is currently being developed by RFI and Trenitalia for the Italian Railways. Other innovative speed supervision systems are being developed in Europe, such as the ETCS/ERTMS, which will also be installed on the new high-speed line Roma-Napoli. All traffic management systems are generally based on a set of supervision curves relating the allowed velocity of the train to the running distance, in order to ensure the respect of speed restrictions on the line by ‘soft’ or ‘hard’ intervention such as an acoustic and visual warning to the driver (soft) and/or service or emergency braking (hard) in the case of train velocity exceeding the permitted one. To elaborate this set of supervision curves, the on-board unit requires train deceleration depending on time and speed as basic information about the braking behaviour of the train. The implementation of a speed supervision system requires a preliminary definition of braking models that allow the conversion of the general parameters affecting the braking performances of trains (such as a braked weight percentage, goods/passenger brake position, brake equipment, train length, etc.) into a basic deceleration profile as a function of time, during the deceleration rise phase, and of speed, during fully developed braking. The deceleration used to evaluate braking curves is obtained by applying a proper safety margin to the nominal deceleration value (which depends on train characteristics). In this paper a probabilistic analysis of train deceleration is carried out, starting from probability distributions of parameters affecting the braking. For the major parameters, the probability distribution was determined on the basis of technical knowledge and experimental results. The aim of this work is to determine the probability that the real deceleration is lower than the nominal value multiplied by a given safety margin.
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Świder, Jerzy, Kamil Szewerda, Krzysztof Herbuś, and Jerzy Jura. "Testing the Impact of Braking Algorithm Parameters on Acceleration and Braking Distance for a Suspended Monorail with Regard to Acceptable Travel Speed in Hard Coal Mines." Energies 14, no. 21 (November 3, 2021): 7275. http://dx.doi.org/10.3390/en14217275.
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Increasing the maximum speed limit of suspended monorails, which became a very popular means of auxiliary transport, is one of the aspects of improving the efficiency of work in underground coal mines. It is especially important to enable higher (than allowed by the law) travel speed, when moving the crew to and from the workplace, which is often very distant from the shaft, and can take more than one hour of travel. Increasing this speed will make it possible to extend the effective working time of miners, which should have a positive impact on the economics of the mine. However, driving at a higher speed is also associated with increased risk of a negative impact of dynamic overload to people, e.g., during emergency braking of the suspended monorail. The concept of sequential emergency braking was developed in order to avoid excessive deceleration affecting passengers and the operator of the monorail, as well as to minimize the dynamic loads acting on the rail suspensions and on the roadway support frames, which could cause serious accidents. The developed assumptions with regard to the new method of braking are innovative in the area related to hard coal mining, where there are currently no such solutions. According to the principles of the developed concept, the total braking force was divided into two stages. The activation of the second stage depends on the deceleration measured after the time delay from activation of the first stage of braking. We present the results of the numerical simulations, which aimed to analyze the impact of changing the parameters of the braking algorithm on the braking deceleration, the braking time, and the braking distance. The possibility of changing the braking force and downward emergency braking on a high inclination angle were also taken into account during the numerical simulations. Use of the developed emergency braking algorithm enables the optimization of this process at a higher speed than is currently used. This aspect is also very important in increasing the safety for people travelling at a higher speed limit. The numerical simulations provide knowledge for safety in terms of the dynamic overload during emergency braking, without injury risk to miners or damage to equipment.
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Koylu, Hakan, and Ali Cinar. "Experimental design of control strategy based on brake pressure changes on wet and slippery surfaces of rough road for variable damper setting during braking with activated anti-lock brake system." Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 226, no. 10 (May 9, 2012): 1303–24. http://dx.doi.org/10.1177/0954407012443443.
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In this study, the control strategy based on experimental study is established for a variable damper setting with activated anti-lock brake system. For this, anti-lock brake system braking tests have been conducted by using hard, medium–hard and soft dampers on a rough road which has wet and slippery surfaces. In anti-lock brake system tests, brake pressure has been measured. The brake pressure increasing and decreasing rates have been obtained using measured brake pressure. The control strategy has been designed by using threshold values acquired from these test results related to brake pressure. For this, firstly, the brake pressure change thresholds of damper providing the shortest braking distance are determined. Then, the damping capacity stage rules are designed by depending on the brake pressure thresholds corresponding to the road conditions. The control strategy performance has been evaluated during transitions between wet and slippery roads. The results show that this control strategy is effectively applied to passenger cars without any change in electronic control unit configuration of anti-lock brake system. For this control strategy, it is considerably important that the damper setting to provide the shortest braking distance is detected.
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Sakhare, Rahul Suryakant, Jairaj Desai, Howell Li, Mischa A. Kachler, and Darcy M. Bullock. "Methodology for Monitoring Work Zones Traffic Operations Using Connected Vehicle Data." Safety 8, no. 2 (June 1, 2022): 41. http://dx.doi.org/10.3390/safety8020041.
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The National Work Zone Safety Information Clearinghouse estimated there were approximately 115,000 work zone crashes with 842 fatalities in 2019. There is broad consensus that it is important for agencies to develop near real-time risk assessment of work zone traffic operations to proactively identify improvement opportunities. Due to the huge spatial distribution and relatively low frequency of crashes, legacy techniques of monitoring crash locations do not scale well for identifying all but the most severe construction zone operational problems. Past research identified hard braking and congestion as strong predictors for crashes in and around work zones. This paper presents scalable methodologies that can be used to systematically analyze hard-braking and speed data obtained from connected vehicles. These techniques have been applied to over 205 billion records in Indiana since 2019. These statewide data analytics are fused into concise graphics to identify work zones with emerging anomalies in congestion and/or hard braking. Weekly screening reports, institutionalized in Indiana for the past two years, provide information for agile agency monitoring and response. Case studies show quantitative changes in work zone performance measures, and corresponding surveillance video images illustrate the significance of these changes. During this period of near real-time monitoring and agile agency response, Indiana interstate crash rates have been reduced by 31% from 2019 to 2021, even though most 2021 interstate traffic volumes have rebounded to pre-pandemic 2019 volumes.
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Vaibhav, R., N. Amutha Prabha, V. Indragandhi, M. Bharathidasan, S. Vasantharaj, and J. Sam Alaric. "Autonomous Braking System Using Linear Actuator." Journal of Sensors 2022 (November 22, 2022): 1–8. http://dx.doi.org/10.1155/2022/7707600.
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The most frequent cause of vehicle accidents (car, bike, truck, etc.) is the unexpected existence of barriers while driving. An automated braking system will assist and minimize such collisions and save the driver and other people’s lives and have a substantial influence on driver safety and comfort. An autonomous braking system is a complicated mechatronic system that incorporates a front-mounted ultrasonic wave emitter capable of creating and transmitting ultrasonic waves. In addition, a front-mounted ultrasonic receiver is attached to gather ultrasonic wave signals that are reflected. The distance between the impediment and the vehicle is determined by the reflected wave. Then, a microprocessor is utilized to control the vehicle’s speed depending on the detected pulse information, which pushes the brake pedal and applies the vehicle’s brakes extremely hard for safety. For work-energy at surprise condition for velocity 20 km/hr, the braking distance is 17.69 m, and for velocity 50 km/hr, the braking distance is 73.14.
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Fambro, Daniel B., Rodger J. Koppa, Dale L. Picha, and Kay Fitzpatrick. "Driver Braking Performance in Stopping Sight Distance Situations." Transportation Research Record: Journal of the Transportation Research Board 1701, no. 1 (January 2000): 9–16. http://dx.doi.org/10.3141/1701-02.
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Assumed driver braking performance in emergency situations is not consistent in the published literature. A 1955 study stated that in an emergency situation “it is suspected that drivers apply their brakes as hard as possible.” This idea differs from a 1984 report that states drivers will “modulate”their braking to maintain directional control. Thus, additional information is needed about driver braking performance when an unexpected object is in the roadway. In this research driver braking distances and decelerations to both unexpected and anticipated stops were measured. The study design allowed for differences in vehicle handling and driver capabilities associated with antilock braking systems (ABS), wet and dry pavement conditions, and the effects of roadway geometry. Vehicle speeds, braking distances, and deceleration profiles were determined for each braking maneuver. The research results show that ABS result in shorter braking distances by as much as 30 m at 90 km/h. These differences were most noticeable on wet pavements where ABS resulted in better control and shorter braking distances. Braking distances on horizontal curves were slightly longer than on tangent sections; however, they were not large enough to be of practical significance. Maximum deceleration during braking is independent of initial velocity, at least in the range of speeds tested. Differences were noted in individual driver performance in terms of maximum deceleration. Although maximum deceleration was equal to the pavement’s coefficient of friction for some drivers, the average maximum deceleration was about 75 percent of that level. Overall, drivers generated maximum decelerations from 6.9 to 9.1 m/s2. The equivalent constant deceleration also varied among drivers. Based on the 90-km/h data, 90 percent of all drivers without ABS chose equivalent constant decelerations of at least 3.4 m/s2 under wet conditions, and 90 percent of all drivers with ABS chose equivalent constant deceleration of at least 4.7 m/s2 on dry pavements.
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Botzer, Assaf, Oren Musicant, and Yaniv Mama. "Relationship between hazard-perception-test scores and proportion of hard-braking events during on-road driving – An investigation using a range of thresholds for hard-braking." Accident Analysis & Prevention 132 (November 2019): 105267. http://dx.doi.org/10.1016/j.aap.2019.105267.
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Anderson, Jeffery R., John Adcox, Beshah Ayalew, Mike Knauff, Tim Rhyne, and Steve Cron. "Interaction of a Slip-Based Antilock Braking System with Tire Torsional Dynamics." Tire Science and Technology 43, no. 3 (September 1, 2015): 182–94. http://dx.doi.org/10.2346/tire.15.430303.
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ABSTRACT This paper presents simulation and experimental results that outline the interaction between a tire's torsional dynamic properties and antilock braking system (ABS) during a hard braking event. Previous work has shown the importance of the coupled dynamics of the tire's belt, sidewall, and wheel/hub assembly on braking performance for a wheel acceleration-based ABS controller. This work presents findings based on a proprietary slip-based ABS controller. A comprehensive system model including tire torsional dynamics, dynamics of the tread–ground friction (LuGre friction model), and dominant brake system hydraulic dynamics was developed for simulation studies on this slip-based controller. Results from key sensitivity studies of tire torsional parameters are presented along with experimental results obtained on a quarter car braking test rig. In this work, it was found that within a reasonable tire design space (with respect to tire torsional properties), the ABS algorithm tested was extremely robust to changing these parameters. The main conclusion of this result is that when a consumer replaces his or her tires with different (than original equipment) tires, there should be little effect on braking performance.
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Pan, Gongyu, and Rongyu Cai. "Thermal Stress Coupling Analysis of Ventilated Disc Brake Based on Moving Heat Source." Advances in Materials Science and Engineering 2018 (December 13, 2018): 1–11. http://dx.doi.org/10.1155/2018/8162028.
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There is a thermomechanical coupling phenomenon in the braking process of vehicle disc brakes. Since the solution time of the direct coupling method is long and it is hard to converge, it is not suitable for analyzing heavy-load braking conditions with long braking time. Meanwhile, the sequential coupling method based on fixed heat source cannot achieve the rotation of friction heat source of the brake disc or accurately simulate the change of temperature. Therefore, Abaqus user subroutine is invoked to achieve the heat source rotation. The results of the simulated temperature field are compared with the results of the complete thermodynamic coupling method, the sequential coupling method based on fixed heat source and dyno test. The comparison shows that the new method combines the advantages of the first two methods and has a better engineering value.
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Mortimer, Rudolf G. "Motorcyclists' Brake Operation, Motorcycle Brake Controls and a Case Study: The Need for Human Factors Engineering." Proceedings of the Human Factors and Ergonomics Society Annual Meeting 46, no. 10 (September 2002): 890–94. http://dx.doi.org/10.1177/154193120204601003.
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A survey was made of the braking techniques reportedly used by 180 motorcyclists in a variety of conditions. Overall, the motorcyclists indicated that they used both front and rear brakes in hard braking 75% of the time on dry pavement and 47% on wet, but in other conditions they mostly used the rear brake first or exclusively. That the rear brake is preferred is not surprising because of the design of the brake controls and other reasons. Reliance on the rear brake at the expense of the front wheel brake leads to reduced deceleration. A crash case study exemplifies the effect. Integrated brakes, in which each brake control simultaneously activates the brakes on the front and rear wheels, are indicated by good human factors design and by motorcyclist's braking performance and should improve safety, especially when the brakes incorporate anti-locking mechanisms
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Kannan, Kasi Rajesh, Ramalingam Vaira Vignesh, Kota Pavan Kalyan, and Myilsamy Govindaraju. "Development and tribological characterization of fly ash reinforced iron based functionally gradient friction materials." Engineering review 41, no. 3 (2021): 20–28. http://dx.doi.org/10.30765/er.1501.
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The tribological and thermal properties enable iron based sintered materials with hard phase ceramic reinforcements as promising friction material for heavy-duty wind turbines. In wind turbines, the braking system consists of aerodynamic and mechanical braking systems. During application of mechanical brakes, the friction materials are pressed against the rotating low-speed shaft. The desired braking efficiency is achieved by utilizing a number of friction materials, which in turn are joined in a steel backing plate. Though this arrangement increases the braking efficiency, the hard phase ceramic reinforcement particles reduces the bonding strength between the friction material and steel backing plate. The joint failure leads to catastrophic failure of wind turbine. Therefore, the need of the hour is to develop friction materials with functional gradients that have high wear resistance (contact area) and high bond strength (interface). In this study, an attempt is made to fabricate and characterize a friction material with gradient profile of composition along the cross section to provide functional gradient property. The functional gradient friction material is synthesized by gradient deposition of Fe, Cu, Cg, SiC and fly ash powders which is then compacted and sintered. The prepared functional gradient friction material was characterized in terms of microstructure and microhardness. The tribological performance (wear rate and coefficient of friction) of the developed functionally gradient friction material was investigated at various loads using pin-on disc apparatus. The results show that as the load increases, the wear rate decreases and at the same time the COF tends to increase at higher loads. The predominant wear mechanism was deduced from the morphology of the worn surface.
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Abdul Hamid, Mohd Kameil, and Gwidon W. Stachowiak. "The Effects of Grit Particle Size on Frictional Characteristics of Automotive Braking System." Advanced Materials Research 189-193 (February 2011): 3511–16. http://dx.doi.org/10.4028/www.scientific.net/amr.189-193.3511.
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The effect of grit particle size on frictional characteristics was investigated using a vertically oriented brake test rig. Silica sand of grit sizes 50-180 µm, 180-355 µm and 355-500 µm were used in drag mode application. Results showed that the presence of hard particles from environment can influence the friction response significantly. Basically, once the hard particles enter the gap, the value and amplitude of friction coefficient tend to decrease. However, slight increase in friction with smaller particles was recorded due to more hard particles involved in mixing and changing the effective contact area. Better friction stability was related to the presence of smaller grit particles and compacted wear debris to form frictional film on the braking interface.
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Nasaruddin, M. A., Mohd Kameil Abdul Hamid, Ahmad Razimi Mat Lazim, and Abd Rahim Abu Bakar. "Effects of External Hard Particles on Brake Noise of Disc Braking System." Applied Mechanics and Materials 388 (August 2013): 213–16. http://dx.doi.org/10.4028/www.scientific.net/amm.388.213.
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The open design and position of disc brake that is closed to road surfaces enable contaminants to enter the brake gap and caused noise and tribological disturbance at the brake interface. Contaminants such as dirt and soil can be present and are expected to influence the occurrence of brake squeal that produce an annoying sound during braking action. The objective of this study was to examine the effect of external hard particles at different disc sliding speed on generation of brake squeal using a brake dynamometer. Different rotational speed of disc brake was selected and the experiments squeal noise data was collected and analyzed using the Fast Fourier Transformation (FFT) analyzer. From the experiments, the presence of external particle and the rotation speed of disc brake promotes the generation of brake squeal phenomenon by changing the surface roughness and effective contact of brake interface. Results obtained from the experiment also showed that higher rotating disc generate higher sound level meter or squeal frequency and increase numbers of squeal noise generated.
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Liu, Luyang, David Racz, Kara Vaillancourt, Julie Michelman, Matt Barnes, Stefan Mellem, Paul Eastham, et al. "Smartphone-based hard-braking event detection at scale for road safety services." Transportation Research Part C: Emerging Technologies 146 (January 2023): 103949. http://dx.doi.org/10.1016/j.trc.2022.103949.
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Feng, Nenglian, Jiawang Yong, and Ziqi Zhan. "A direct multiple shooting method to improve vehicle handling and stability for four hub-wheel-drive electric vehicle during regenerative braking." Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 234, no. 4 (August 6, 2019): 1047–56. http://dx.doi.org/10.1177/0954407019867510.
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Regenerative braking is an important technology to improve fuel economy for electric vehicles. Apart from improving energy recovery efficiency and vehicle stability, the arithmetic speed of the algorithm is also essential for an automotive-qualified micro control units. This paper presents a direct multiple shooting method–based algorithm to achieve multiple objectives for four hub-wheel-drive electric vehicle during mild braking situations. Mathematical models of the system are generated for numerical simulations in MATLAB, including a vehicle dynamics model, a modified tire model, a single-point preview driver model, and a regenerative braking motor efficiency map. With the limitation of hard constraint and minimization of adjustment rate in cost function, optimization tends to be accomplished by distribution of braking torque in front and rear wheels. Furthermore, the control strategy has been realized using a direct multiple shooting method to convert the nonlinear optimal control problem to a nonlinear programming problem, which will be settled by adopting a sequential quadratic programming method in each subintervals. The effectiveness and adaptation of the control strategy for four hub-wheel-drive electric vehicle has been evaluated by conducting many simulations during mild braking situations, and the simulation results also demonstrated that the direct multiple shooting–based strategy exhibits a better performance than that of proportional-integral-based or nonlinear model predictive control–based controller.
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Bradshaw, Elizabeth J., and W. A. Sparrow. "The Effects of Target Length on the Visual Control of Step Length for Hard and Soft Impacts." Journal of Applied Biomechanics 18, no. 1 (February 2002): 57–73. http://dx.doi.org/10.1123/jab.18.1.57.
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Adjustments to gait were examined when positioning the foot within a narrow target at the end of an approach for two impact conditions, hard and soft. Participants (6 M, 6 F) ran toward a target of three lengths along a 10-m walkway consisting of two marker strips with alternating black and white 0.5-m markings. Five trials were conducted for each target length and impact task, with trials block randomized between the 6 participants of each gender. A 50Hz digital video camera panned and filmed each trial from an elevated position adjacent to the walkway. Video footage was digitized to deduce the gait characteristics. A linear speed/accuracy tradeoff between target length and approach time was found for both impact tasks (hard, r = 0.99, p < 0.01; soft, r = 0.96, p < 0.05). For the hard-impact task, visual control time increased linearly (r = 0.99, p < 0.05) when whole-body approach velocity decreased. Visual control time was unaffected by whole-body approach velocity in the soft-impact task. A constant tau-margin of 1.08 describes the onset of visual control when approaching a target while running, with the control of braking during visual control described by a tau-dot of –0.85. Further research is needed to examine the control of braking in different targeting tasks.
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Imbeau, Daniel, Joseph-Jean Paques, Sylvie Bergeron, and Réal Bourbonnière. "Crane movement limiting device design for safe operation near power lines." Occupational Ergonomics 1, no. 2 (April 1, 1998): 95–105. http://dx.doi.org/10.3233/oer-1998-1202.
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Performance of experienced crane operators in stopping rotational movements of a crane platform was compared with that of an automatic braking system. Sixteen certified crane operators performed boom movements towards a segment of a typical power line using a 100 tons lifting capacity crane equipped with a fixed-length 18 m long boom, a single lifting cable, and hard ball hook. The 18 m boom was later replaced with a 49 m boom to vary crane geometry and motion response. In all trials, a 1500 kg (3500 lb) load was hooked to the lifting cable. In critical operating conditions, the control input strategy used by the experienced crane operators could yield a stopping angle comparable to that of the automatic braking system. However, when compared with the automatic braking system, the operators had a better control on the oscillations of the load during the stopping maneuver. The data collected in this experiment were used to specify two key parameters in the design of a crane movement limiting device.
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Vivas-Lopez, Carlos A., Juan C. Tudon-Martinez, Diana Hernandez-Alcantara, and Ruben Morales-Menendez. "Global Chassis Control System Using Suspension, Steering, and Braking Subsystems." Mathematical Problems in Engineering 2015 (2015): 1–18. http://dx.doi.org/10.1155/2015/263424.
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A novelGlobal Chassis Control(GCC) system based on a multilayer architecture with three levels: top: decision layer, middle: control layer, and bottom: system layer is presented. The main contribution of this work is the development of a data-based classification and coordination algorithm, into a single control problem. Based on a clustering technique, the decision layer classifies the current driving condition. Afterwards, heuristic rules are used to coordinate the performance of the considered vehicle subsystems (suspension, steering, and braking) using local controllers hosted in the control layer. The control allocation system uses fuzzy logic controllers. The performance of the proposed GCC system was evaluated under different standard tests. Simulation results illustrate the effectiveness of the proposed system compared to an uncontrolled vehicle and a vehicle with a noncoordinated control. The proposed system decreases by 14% the braking distance in the hard braking test with respect to the uncontrolled vehicle, the roll and yaw movements are reduced by 10% and 12%, respectively, in the Double Line Change test, and the oscillations caused by load transfer are reduced by 7% in a cornering situation.
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Zhao, Shaodi, Jiusheng Bao, Qingjin Zhang, Yan Yin, Xiaoyang Wang, and Junwei Ai. "Preparation process optimization of hard magnetic brake friction material based on NdFeB additive." Industrial Lubrication and Tribology 74, no. 2 (January 27, 2022): 258–64. http://dx.doi.org/10.1108/ilt-07-2021-0243.
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Purpose This study aims to develop magnetic field-controlled friction braking technology, the preparation process of hard magnetic brake friction material was optimized and analyzed in this paper. Design/methodology/approach NdFeB, a rigid magnetic material, was selected as additive. Magnetic field orientation, a part of material preparation, was added to the preparation process. Experiments investigated the tribological properties of each brake lining sample. The preparation process of the hard magnetic friction material was optimized based on fuzzy theory by using analytic hierarchy process (AHP) methods and SPSS software. The microscopic morphology and the distribution and content of elements of friction lining samples prepared with or without orientation excitation voltage were analyzed by scanning electron microscope and energy dispersive X-ray microanalysis. Findings The results showed that the tribological properties of brake lining samples could be improved by process optimization and the oriented excitation voltage can effectively improve the properties of the brake lining. Originality/value The magnetic field orientation was added into the traditional preparation process, and a set of process parameters with the best tribological properties were obtained through optimization. It is believed that this research will be of great theoretical and practical significance to develop both new brake materials and active control technology of the braking process in the future.
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Aghasizade, Sajjad, Mehdi Mirzaei, and Sadra Rafatnia. "Novel constrained control of active suspension system integrated with anti-lock braking system based on 14-degree of freedom vehicle model." Proceedings of the Institution of Mechanical Engineers, Part K: Journal of Multi-body Dynamics 232, no. 4 (January 18, 2018): 501–20. http://dx.doi.org/10.1177/1464419317752612.
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This paper deals with a novel method for integration of the active suspension system and the anti-lock braking system. In the proposed method, a new nonlinear controller with state constraints is developed for the active suspension system based on the response prediction of 14-degree of freedom vehicle model. The proposed controller isolates the vehicle from road roughness in normal conditions and assists the anti-lock braking system by ensuring a good contact between the tyre and road during hard braking. In addition, the tyre deflection is limited to prevent the threat of tyre bursting. To develop the active suspension system controller, at first, a performance index consisting of a weighted combination of predicted responses of suspension system is expanded as a function of current control input. At the same time, the state constraints of tyre normal force and tyre deflection are transformed to the equivalent constraints of control input by the same prediction approach. Then, the control law is found by minimizing the expanded performance index in the presence of input constraints. The Karush–Kuhn–Tucker theorem is employed to solve the performed constrained optimization problem analytically. The performance of the proposed active suspension system controller integrated with the designed nonlinear anti-lock braking system controller is evaluated for a full vehicle model including roll and pitch motions during braking on irregular random roads. The results show that both the body acceleration and the vehicle stopping distance are decreased for the proposed integrated strategy compared with other conventional strategies.
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Njobelo, Gwamaka, Thobias Sando, Soheil Sajjadi, Enock Mtoi, Eren Erman Ozguven, and John Sobanjo. "Safety Evaluation of the Advanced Stop Assist System in Connected Vehicle Environment." Transportation Research Record: Journal of the Transportation Research Board 2672, no. 22 (October 23, 2018): 47–57. http://dx.doi.org/10.1177/0361198118797831.
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Although traffic signals are installed to reduce the overall number of collisions at intersections, certain types, in particular, rear-end collisions are increasing due to signalization. One dominant factor associated with rear-end crashes is the indecisiveness of the driver, especially in the dilemma zone. An advisory system to help the driver make the stop-or-pass decision would greatly improve intersection safety. This study proposes and evaluates an Advanced Stop Assist System (ASAS) at signalized intersections by using Vehicle-to-Infrastructure (V2I) communication. The proposed system utilizes communication data, received from roadside equipment, to provide approaching vehicles with vehicle-specific advisory speed messages to prevent vehicle hard-braking at a yellow or red signal. A simulation test bed was modeled using VISSIM, a microscopic simulation software, to evaluate the effectiveness of the proposed system. The results demonstrate that at full market penetration (100% saturation of vehicles equipped with on-board communication equipment), the proposed system reduces the number of hard-braking vehicles by nearly 50%. Sensitivity analyses of market penetration rates also show a degradation in safety conditions at penetration rates lower than 40%. The results suggest that a penetration rate of at least 60% is required for the proposed system to minimize rear-end collisions and improve safety at the signalized intersections.
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Itani, Khaled, and Alexandre De Bernardinis. "Electrothermal Multicriteria Comparative Analysis of Two Competitive Powertrains Applied to a Two Front Wheel Driven Electric Vehicle during Extreme Regenerative Braking Operations." Energies 15, no. 22 (November 14, 2022): 8506. http://dx.doi.org/10.3390/en15228506.
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The powertrain performance in an electric vehicle is fully dependent on the electrical and thermal constraints of the static converters ensuring the power transfer taking place between the energy storage systems and the electromechanical machines. These constraints depend on the architectures of the power converters, and their control strategies. Particularly, the maximal limits are reached in maneuvers such as hard regenerative braking circumstances. Indeed, braking recovery is a critical phase in the vehicle’s operation, and its duration and intensity may strongly impact the vehicle’s battery behavior or integrated hybrid storage system. The innovative objective of the paper is to propose an electrothermal multicriteria comparative study based on electrical and thermal criteria for two competitive powertrains. These semi-active power configurations (a 3-level DC/DC converter-based, and a Z-source converter-based) are implemented in a two-front wheel driven electric vehicle during extreme regenerative braking conditions. Open-loop and closed-loop controls were implemented in the Z-source using the maximal constant boost control with 3rd harmonic injection modulation technique. We considered two paralleled IGBT modules instead of the single shoot-through structure. Our approach is based on simulation during an extreme braking maneuver leading to heavy repercussions on the overall powertrain system. The aim is to investigate the challenging structure of the Z-source. Results showed that the proposed 3-level DC/DC-based topology has better performances in terms of power losses, efficiency, thermal behavior, and electromagnetic interference.
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Žukas, Artūras, Jurijus Zaranka, and Kristina Kemzūraitė. "COMPARISONAL ANALYSIS OF MANUEVERING AND BRAKING." Mokslas - Lietuvos ateitis 2, no. 6 (December 31, 2010): 90–93. http://dx.doi.org/10.3846/mla.2010.119.
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This article covers the possibility of avoiding a traffic accident considering a car driver who is fallen in a dangerous situation. In such a case, the driver can choose one of the following ways: hard braking or one of the types of maneuvering, including turning off, turning with straightening or changing a line regarding road surface type (dry asphalt, wet asphalt or snowy asphalt). The article also proposes formulas for calculating road distance the car travels till dead stop. Moreover, the tables display theoretical values taking into account various car speeds and road surfaces. The pictures help with determining the most suitable type of action in light of road and weather conditions as well as car speed. The pictures clearly show the dependence of road length on movement speed. At the end of the article, conclusions are proposed.
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Sharke, Paul. "No Breaks for Noise." Mechanical Engineering 121, no. 08 (August 1, 1999): 62–63. http://dx.doi.org/10.1115/1.1999-aug-5.
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This article highlights the fact that engineers who design and test anti-lock brake systems (ABS) have been trying to come up with ways to minimize the noise and vibration that drivers hear and feel when they stomp on the brake pedals. The ABS engineers want drivers to do during a panic stop is to let their feet off the brakes. According to the engineers, braking should be the concern, because the less time the driver worries about stopping the car, the more time there is to concentrate on steering it. The mechanical components in both systems are functionally identical, consisting of a brake pedal, a master cylinder and booster, hydraulic lines and fluid, wheel calipers, brake pads, and rotors. In fact, unless the system is actuated by hard braking, ABS acts just like an ordinary disc brake system. Engine noise would only mask the ABS noise reaching the binaural head, which sits inside the passenger compartment where a driver would normally be.
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Vrabel, J., T. Skrucany, L. Bartuska, and J. Koprna. "Movement analysis of the semitrailer with the tank-container at hard braking -the case study." IOP Conference Series: Materials Science and Engineering 710 (December 19, 2019): 012025. http://dx.doi.org/10.1088/1757-899x/710/1/012025.
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Liu, Xin Tian, Li Hui Zhao, Hu Huang, Yan Song Wang, and Hao Chen. "Influence of Outer Rubber Bushing Stiffness of the under Control Arm on Multi-Link Independent Suspension Performance." Applied Mechanics and Materials 52-54 (March 2011): 578–82. http://dx.doi.org/10.4028/www.scientific.net/amm.52-54.578.
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Multi-link independent suspension is built according to the hard point parameters of a car. According to the multi-body dynamics and Suspension Kinematics theory, with the working condition of wheel travel and braking, the suspension performance is analyzed and discussed by changing rubber bushing stiffness of under control arm. The conclusion is drawn that axial stiffness of rubber bushing has almost no effect on the suspension performance, but radical stiffness has a little effect and torsion stiffness has the biggest effect on the suspension performance of these three parameters.
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Coux, Martin, and John M. Kolinski. "Surface textures suppress viscoelastic braking on soft substrates." Proceedings of the National Academy of Sciences 117, no. 51 (December 4, 2020): 32285–92. http://dx.doi.org/10.1073/pnas.2008683117.
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A gravity-driven droplet will rapidly flow down an inclined substrate, resisted only by stresses inside the liquid. If the substrate is compliant, with an elastic modulusG< 100 kPa, the droplet will markedly slow as a consequence of viscoelastic braking. This phenomenon arises due to deformations of the solid at the moving contact line, enhancing dissipation in the solid phase. Here, we pattern compliant surfaces with textures and probe their interaction with droplets. We show that the superhydrophobic Cassie state, where a droplet is supported atop air-immersed textures, is preserved on soft textured substrates. Confocal microscopy reveals that every texture in contact with the liquid is deformed by capillary stresses. This deformation is coupled to liquid pinning induced by the orientation of contact lines atop soft textures. Thus, compared to flat substrates, greater forcing is required for the onset of drop motion when the soft solid is textured. Surprisingly, droplet velocities down inclined soft or hard textured substrates are indistinguishable; the textures thus suppress viscoelastic braking despite substantial fluid–solid contact. High-speed microscopy shows that contact line velocities atop the pillars vastly exceed those associated with viscoelastic braking. This velocity regime involves less deformation, thus less dissipation, in the solid phase. Such rapid motions are only possible because the textures introduce a new scale and contact-line geometry. The contact-line orientation atop soft pillars induces significant deflections of the pillars on the receding edge of the droplet; calculations confirm that this does not slow down the droplet.
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Safronov, Oleksandr, Yurii Vodiannikov, Pavlo Khozia, and Anton Mozheiko. "BRAKING EFFICIENCY OF QUARRY TRAINS WITH SIX-BOGIES DUMP CARS OF THE INCREASED AXIAL LOAD UP TO 27.7 TF." Railbound Rolling Stock, no. 23 (December 16, 2021): 111–26. http://dx.doi.org/10.47675/2304-6309-2021-23-111-126.
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Improving the technical level of railway transport of industrial enterprises is expressed in the introduction of advanced types of traction (locomotives and electric locomotives), four and six-axle specialized cars, including self-unloading, automation and telemechanics. To increase the productivity of quarry trains at PJSC "Kryukiv Railway Car Building Plant" a six-axle dump car model 33-7141 for quarry railway transport was designed. The car is designed for transportation from quarries of open cut hard rocks, ore and other bulk and lump cargo with density (1.75-4.0) t/m3, as well as mechanized unloading on dumping sites or crushing units of opencast mining. A distinctive feature of innovative dump cars from typical ones is the increase of cargo weight by 10 t and axial load to 271.6 (27.7) kN (ts). In this regard, the issues of assessing the braking efficiency of a quarry train with innovative dump cars that meet the requirements for railway industrial transport are becoming relevant. The article presents the study results of the braking efficiency of a quarry train composition of 10 and 14 cars. Locomotive TEM7 and unit OPE1AM with one and two motor cars were considered as traction units. The maximum permissible speeds were determined in a given range of slopes of the railway track, and the maximum possible descent was set provided that the braking distance does not exceed or will be equal to 300. As a result of research, it was found that the maximum allowable deviations ranged from 34 ‰ to 38 ‰ depending on the number of cars and traction units. The speed of trains with innovative dump trucks on the site is 42 km/h. Key words: dump car, tipping wagon, maximum slope, permissible speed, braking distance, traction unit.
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Yan, Xiaonan, Liangliang Tao, Junqin Peng, Yanhua Zeng, Yong Fang, and Yun Bai. "Behavior of Piston Wind Induced by Braking Train in a Tunnel." Energies 13, no. 23 (December 4, 2020): 6420. http://dx.doi.org/10.3390/en13236420.
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It is critical to discover the behavior of piston wind induced by a braking train in a tunnel, but there is little research on the theoretical derivation for piston wind behavior. Predicting piston wind behavior as an unsteady airflow by a theoretical formula is hard work due to the complexity of train running states and airflow fields. Herein, we develop a mathematical model to investigate the behavior of piston wind as an unsteady airflow, considering the variation of wind direction in the annular area. In general, the theoretical model is validated by experiments. However, experimental studies about piston wind are scarce. In this study, we simulated the emergent braking process of a train to validate the mathematical model by establishing a 1/50 scaled experimental configuration. The piston wind data tested in the experiment have good agreement with the results calculated by theoretical formulas. In addition, sensitivity analysis of the effect parameters of piston wind (i.e., tunnel length, train length, train speed and blockage ratio) was conducted. The theoretical formulas derived in this paper are applicable to similar train running conditions in railway tunnels or subway tunnels.
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Pytlik, Andrzej. "Tests of steel arch and rock bolt support resistance to static and dynamic loading induced by suspended monorail transportation." Studia Geotechnica et Mechanica 41, no. 2 (June 28, 2019): 81–92. http://dx.doi.org/10.2478/sgem-2019-0009.
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AbstractAt present, the suspended monorail systems constitute a very common means of transportation in the Polish hard coal mines. The main advantages of the suspended monorail include the independence of the route from the working floor surface irregularities and the possibility to transport cargo of significant mass and size.The masses and dimensions of machines and devices transported via monorail have increased considerably in recent times. This particularly concerns the transport of longwall system elements. In Poland, the maximum speed of suspended monorail travel is 2 m/s. Due to the fact that preparations are currently underway to increase the maximum speed above 2 m/s, it is necessary to inspect what influence it will have on work safety and mining support stability.Current operational experience and tests have shown that dynamic loads induced by the suspended monorail transportation have a significant influence on the roadway support stability, working protection durability and on the monorail operators. This is particularly true during the emergency braking of a suspended monorail by means of a braking trolley, where the overloads reach 3g.Bench tests of the selected steel arch and rock bolt support elements utilised in the Polish hard coal mines were conducted in order to determine the resistance of steel arch and rock bolt supports to static and dynamic loads.The article presents the results of the tests conducted on a steel arch support in the form of the sliding joints of an ŁP/V29 yielding roadway support, which is commonly employed in the Polish hard coal mines. Tests of elements of the threaded bolts with trapezoidal threads over the entire rod length were conducted as well.The conducted strength tests of steel arch and rock bolt support elements under static and dynamic loading have shown that dynamic loading has decisive influence on the support’s retaining of its stability. Support element stability decreases along with the increase of the impact velocity. This concerns both the steel arch support and the rock bolt support.
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Kılıç, Halil, Cenk Mısırlı, İbrahim Mutlu, and Mustafa Timur. "Mechanical and tribological properties of a WC-based HVOF spray coated brake disc." Materials Testing 64, no. 8 (August 1, 2022): 1150–61. http://dx.doi.org/10.1515/mt-2022-0077.
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Abstract Thermally sprayed WC-based coating systems are generally used to increase engineering components’ wear resistance. This research presents the results of a comparative study conducted to examine the tribological characteristics of a new brake disc created with thermal sprayed WC-10Co4Cr coating. This study implemented braking tests on the WC-10Co4Cr coated brake disc against commercial friction material on a laboratory scale disc-pad tester and compared the findings with the reference disc. The coating system was created with a high velocity oxygen-fuel spraying on a cast iron disc. The braking tests followed the sections of the SAE-J2430 test procedure. The microstructure, phase composition and properties of the coating were characterized by SEM/EDS, XRD and Vickers microstructure. The effect of carbide coating on the friction and wear behaviour of the tribological system was examined. The WC-10Co4Cr coating has increased the hardness by 3 times with a thickness of 300 μm compared to the cast iron surface. The amount of wear in the coated disc (CD) was reduced by about 85% compared to the reference disc (BD). The coefficient of frictions of BD and CD was found to be in the range of 0.43–0.61 and 0.47–0.62, respectively. The inclusion of hard phases (WC and W2C) in the disc coating played an important role in improving the sliding wear resistance by maintaining the coefficient of friction of the brake disc at an acceptable level. In brief, carbide coating could be claimed to be promising for challenging braking implementations.
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Saka, Anthony A., and Richard A. Glassco. "Modeling Traffic Safety Benefits of Intelligent Transportation System Technologies at Truck Inspection Facilities: Microscopic Simulation." Transportation Research Record: Journal of the Transportation Research Board 1779, no. 1 (January 2001): 173–81. http://dx.doi.org/10.3141/1779-23.
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A microscopic simulation model was developed to capture the traffic safety benefits of using intelligent transportation system (ITS) technologies, including weigh-in-motion scales with variable message signs, at truck inspection facilities. The development of the simulation model was motivated by prevalent safety concerns at congested truck inspection facilities nationwide. Three primary safety components (roadway, driver, and vehicle) were considered in the model. The roadway component focuses on the varying size of truck queues at inspection facilities and safety implications. The driver component captures key human factor elements and their variability, including distributions for perception-reaction time, speed, gap acceptance, headway, and braking characteristics. The vehicular component incorporates the size distribution of vehicles (trucks and nontrucks), proportion of trucks with defective braking systems, and their safety implications with respect to stopping distance. The primary objective for the model is to depict variations in traffic pattern for baseline (pre-ITS) and post-ITS situations. Measures of effectiveness used for evaluating traffic benefits of using ITS technologies include percent reduction in sudden deceleration of vehicles resulting from shock wave phenomena and percent reduction in duration of truck-queue overflow resulting from a high traffic intensity. Results from simulation runs support the hypothesis that the use of ITS technologies at truck inspection facilities significantly reduces the frequency of experiencing the high-risk traffic phenomena (e.g., hard braking and truck-queue overflow). The postulation is made that the reduction in the frequency of high-risk phenomena will translate into a decrease in the likelihood of experiencing crash-related incidents in the vicinity of truck inspection facilities.
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Babulal, Ganesh M., Sarah H. Stout, Tammie L. S. Benzinger, Brian R. Ott, David B. Carr, Mollie Webb, Cindy M. Traub, et al. "A Naturalistic Study of Driving Behavior in Older Adults and Preclinical Alzheimer Disease: A Pilot Study." Journal of Applied Gerontology 38, no. 2 (January 29, 2017): 277–89. http://dx.doi.org/10.1177/0733464817690679.
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A clinical consequence of symptomatic Alzheimer’s disease (AD) is impaired driving performance. However, decline in driving performance may begin in the preclinical stage of AD. We used a naturalistic driving methodology to examine differences in driving behavior over one year in a small sample of cognitively normal older adults with ( n = 10) and without ( n = 10) preclinical AD. As expected with a small sample size, there were no statistically significant differences between the two groups, but older adults with preclinical AD drove less often, were less likely to drive at night, and had fewer aggressive behaviors such as hard braking, speeding, and sudden acceleration. The sample size required to power a larger study to determine differences was calculated.
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Jian, Qifei, and Yan Shui. "Numerical and experimental analysis of transient temperature field of ventilated disc brake under the condition of hard braking." International Journal of Thermal Sciences 122 (December 2017): 115–23. http://dx.doi.org/10.1016/j.ijthermalsci.2017.08.013.
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Cham, D. M., M. Shanmugavel, and V. R. Sampathkumar. "Simulation of Vehicle Steering Angle and Lateral Acceleration in Mitigating Potential Run-Off-Road Crashes." Journal of the Society of Automotive Engineers Malaysia 1, no. 3 (April 28, 2021): 251–61. http://dx.doi.org/10.56381/jsaem.v1i3.60.
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This paper proposes and presents the preliminary results of an integrated safety warning system for road vehicles based on lateral g-force monitoring. The proposed system issues a warning to the driver when the lateral load increases above a threshold level thereby reducing the risk of run-off-road crashes and loss of control. From the vehicles dynamic model, soft and hard speed limits are obtained. When the soft limit is breached, it warns the driver using a LED, and when the hard limit is breached, assistive braking is activated. Simulations were conducted to obtain the safe vehicle speed for various steering angle to ensure the lateral g-force remains in the range of 0.7 and 0.9. Vehicle parameters of the Proton Saga 1.3L were used for simulation. Simulation runs to study the effects of changes in steering-wheel angle and vehicle speed on the variation of lateral acceleration was performed, based on which a safe speed is obtained. Simulations were also conducted on both banked and unbanked roads. The results of this study would help in the design of a working prototype of the safety system.
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Venkatachalam, G., and A. Kumaravel. "Mechanical Behaviour of Aluminium Alloy Reinforced with Sic/Fly Ash/Basalt Composite for Brake Rotor." Polymers and Polymer Composites 25, no. 3 (March 2017): 203–8. http://dx.doi.org/10.1177/096739111702500304.
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Gray cast iron is the most commonly used material in automobile brake rotors. It generates heat easily during braking which affects its mechanical properties and the Coefficient of friction varies depending on the type of material used for the brake rotor. Aluminium (Al) based metal matrix composite can be an efficient and effective braking material compared to cast iron and matrix alloy. In the present investigation, Al6082 composites were fabricated by stir casting method by varying weight percentage of reinforcements for Sample1 (Al 90% + SiC 10%), Sample 2 (Al 90% + SiC 5% + fly ash 5%) and Sample 3 (Al 90% + SiC 5% + basalt 5%). Chemical compositions, micro hardness, wear test and tensile test were performed to study the mechanical behavior of all the test specimens. The surface morphology was studied using microscopic inspection to indicate the distribution of reinforcement particles and bonding between the matrixes. Composites containing hard oxides (like SiC) are preferred for high wear resistance along with increased hardness and high temperature oxidation resistance. The result reveals that wear rates of the composite materials is lower than that of the matrix alloy and friction coefficient was minimum. Also, it improves the micro hardness and tensile strength. The addition of fly ash and basalt decreases the wear and it acquired density almost three times lower than that of gray cast iron. In this investigation, the alternate materials for automobile brake rotors with Al reinforced composites were studied.
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Klauer, Sheila G., Vicki L. Neale, Thomas A. Dingus, David Ramsey, and Jeremy Sudweeks. "Driver Inattention: A Contributing Factor to Crashes and Near-Crashes." Proceedings of the Human Factors and Ergonomics Society Annual Meeting 49, no. 22 (September 2005): 1922–26. http://dx.doi.org/10.1177/154193120504902208.
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Driver distraction, or inattention, has been receiving wide media attention recently as many state legislatures are considering various levels of restricting cell phone use. Research has been conducted using a variety of experimental methods to determine the level of risk associated with driving inattention. While most of this research suggests that inattention impairs driving, there have been no studies to directly link driving inattention to crashes. Data from the 100-Car Naturalistic Driving Study, an instrumented vehicle study for which data was collected on 100 drivers in the Washington, DC metropolitan area for 12 months, were used in the following analyses. Crashes and near-crashes were identified in the data using post-hoc triggers based upon driving performance metrics, (i.e. hard braking). Results suggest that inattention contributed to 78% of all crashes collected over the 12 month data collection period.
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Aarseth, Sverre J. "Star Cluster Simulations on HARP." Symposium - International Astronomical Union 174 (1996): 161–70. http://dx.doi.org/10.1017/s0074180900001492.
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We describe some aspects of implementing star cluster simulations on HARP. The code NBODY4 employs the Hermite scheme with hierarchical block-steps for direct integration. The algorithms have been optimized for parallel processing with the eight pipeline HARP-2 delivering a peak performance of about 1.7 Gflops for N = 104 particles. Hard binaries are studied by KS regularization which also uses the Hermite scheme, whereas strong interactions between 3–5 particles are treated by chain regularization. Astrophysical processes modelled include mass loss by stellar evolution, two-body tidal interaction, Roche lobe mass transfer, common envelope evolution, magnetic braking and gravitational radiation. Consistent values of stellar radii and evolution type are obtained by fast look-up. A new formulation of collision outcomes yields blue stragglers and other exotic objects. Some recent results for an open cluster model are presented.
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Szafran, Krzysztof Stanisław, and Ireneusz Kramarski. "Fatigue Degradation of the Ram-Air Parachute Canopy Structure." Fatigue of Aircraft Structures 2019, no. 11 (December 1, 2019): 103–12. http://dx.doi.org/10.2478/fas-2019-0010.
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AbstractIn this work, the authors continue researching issues related to fatigue of aircraft structures made of fabrics. Parachute systems are widely used in military, sport and recreational aviation. Braking parachutes as well as skydiving and troop parachutes are characterized by the repeated use of parachute canopies, which are exposed to wear and fatigue. Until now, parachutes were difficult to design aviation systems due to their complex and unsteady opening characteristics, large changes in the geometry of canopies, suspension lines and tape risers as well as exposure to stochastic atmospheric turbulence. The fatigue of the canopy fabric, suspension lines and tape risers is a problem that must be addressed by textile designers and designers of reusable parachute systems. The authors of this work demonstrate the complexity of operating a parachute in hard multiple use conditions and propose ways to extend the parachute’s service life without compromising safety.