scholarly journals Experimental investigation of tire performance on slush

2021 ◽  
Vol 23 (1) ◽  
pp. 103-109
Author(s):  
Andrius Ružinskas ◽  
Martin Giessler ◽  
Frank Gauterin ◽  
Klaus Wiese ◽  
Marijonas Bogdevičius
Keyword(s):  
Experimental Investigation ◽  
Standard Deviation ◽  
Road Safety ◽  
Peak Force ◽  
Good Reproducibility ◽  
Force Coefficient ◽  
High Importance ◽  
Opposite Trend ◽  
Tire Friction ◽  
Crushed Ice

An investigation of tires behaviour on winter roads was always a high importance in the context of road safety. This paper presents the experimental investigation of tire performance on slush that is identified as two mixtures: a mixture of snow and water, and a mixture of crushed ice and water. The measurements of longitudinal and lateral performance including tire traction, braking and cornering were performed. Tire traction tests were performed for both mixtures with different amount of material. A decreasing in the tire friction was observed when amount of the mixture of snow and water was increased twice. For the mixture of crushed ice and water, an opposite trend was observed. The standard deviation values for the peak force coefficient showed a good reproducibility and reliability of performed tire tests.

Effect of Trailing-Edge Flap Deflection on a Symmetric Airfoil Over a Wavy Ground

2018 ◽  
Vol 141 (6) ◽  
Author(s):  
V. Tremblay-Dionne ◽  
T. Lee
Keyword(s):  
Experimental Investigation ◽  
Pitching Moment ◽  
Cyclic Variation ◽  
Trailing Edge ◽  
Opposite Trend ◽  
Aerodynamic Properties ◽  
Trailing Edge Flap ◽  
Flap Deflection ◽  
Naca 0015

The effect of trailing-edge flap (TEF) deflection on the aerodynamic properties and flowfield of a symmetric airfoil over a wavy ground was investigated experimentally. This Technical Brief is a continuation of Lee and Tremblay-Dionne (2018, “Experimental Investigation of the Aerodynamics and Flowfield of a NACA 0015 Airfoil Over a Wavy Ground,” ASME J. Fluids Eng., 140(7), p. 071202) in which an unflapped airfoil was employed. Regardless of the flap deflection, the cyclic variation in the sectional lift Cl and pitching moment Cm coefficients over the wavy ground always persists. The Cm also has an opposite trend to Cl. The flap deflection, however, produces an increased maximum and minimum Cl and Cm with a reduced fluctuation compared to their unflapped counterparts. The Cd increase outperforms the Cl increase, leading to a lowered Cl/Cd of the flapped airfoil.

An experimental investigation on the use of a rectangular strut in a scramjet thruster for thrust vector control

2020 ◽  
pp. 095441002097312
Author(s):  
DR Biju Ben Rose ◽  
BTN Sridhar
Keyword(s):  
Experimental Investigation ◽  
Vector Control ◽  
Wall Pressure ◽  
Laboratory Model ◽  
Ambient Atmosphere ◽  
Pitching Moment ◽  
Force Coefficient ◽  
Side Force ◽  
Thrust Vector Control ◽  
Thrust Vector

An experimental investigation was carried out to find the effect of a strut spanning across the width of a single expansion ramp of a laboratory model scramjet thruster as a thrust vector control device. Cold flow tests were conducted with operating total pressures ranging from 4 bar to 10 bar and the thruster exhaust was to ambient atmosphere. The mass flow rate varied from 0.105 kg/s to 0.263 kg/s. Experiments were conducted by varying the strut height at different operational total pressures to find if any thrust vector control could be achieved to supplement the maneuverability of hypersonic vehicle with aerodynamic control. The laboratory model consisted of an isolator, a divergent combustor followed by a single expansion ramp. Except the side walls, the thruster was fabricated with stainless steel. A high quality acrylic sheet was used for internal flow visualization by a schilieren system. The wall pressure was recorded at different locations from the combustor inlet to ramp trailing edge. Shock pattern was studied from the schilieren images and it was observed that an increase in strut height caused a downward deflection of the exhaust. From the wall pressure distribution, two dimensional side force coefficient and pitching moment coefficient were calculated and the effect of strut height variation on the above coefficients was plotted. Results from experiments indicated that the presence of the strut yielded noticeable changes in side force and pitching moment. The increase in strut height provided exhaust stream directional changes which may be useful in maneuvering the vehicles employing scramjet propulsion system.

Numerical Simulation of the Mechanical Structure of a Helmet Motorcyclist

2013 ◽  
Vol 856 ◽  
pp. 368-372 ◽  
Author(s):  
Bessai Naïma ◽  
Boudjemaa Fatiha ◽  
Lounis Mourad ◽  
Baumgartner Danie
Keyword(s):  
Numerical Simulation ◽  
Kinetic Energy ◽  
Road Safety ◽  
Main Function ◽  
Dynamic Reaction ◽  
Modern Life ◽  
High Importance ◽  
Protective System ◽  
Shock Impact ◽  
The Impact

Road safety is of high importance in our modern life in terms of social and economic. The helmet is the head protective system the most common used. Their main function is to reduce or prevent damage that may occur during an impact due to an accident. The head will be better protected if the more important quantity of the energy caused by the kinetic energy of the impact is absorbed by the helmet. The greater part of the impact energy should be absorbed by the deformations of the different layers of the helmet. The analytic equations of the model of the helmet parts show a realistic dynamic reaction of the different layers after the shock impact. These results will permit a better comprehension of the helmet behaviour to violent impact and the energy distribution in the different layers so a better optimisation of the head helmet in the future.

scholarly journals Regression to the mean correction for Collision Modification Factors

2021 ◽  
Author(s):  
Bernard James
Keyword(s):  
Standard Deviation ◽  
Road Safety ◽  
Relative Number ◽  
Highway Safety ◽  
Regression To The Mean ◽  
Simple Method ◽  
Highway Safety Manual ◽  
The Mean ◽  
Site Population

Collision Modification Factors (CMFs) are a simple method of representing the effectiveness of road safety treatments. With the release of the Highway Safety Manual (HSM) and the recent launching of a CMF Clearinghouse website, CMFs are likely to become more widely used for estimating the effects of potential road safety treatments. The presence of regression to the mean (RTM) bias has long been shown to affect the accuracy of CMFs that did not account for the RTM in their development. The purpose of this research was to study how the RTM depends on the number of years of data used for selecting high collision sites for treatment and on the relative number of sites selected. From this analysis, a function based on the number of years, percentage of high collision sites selected, and the mean and standard deviation of the site population from which the treated sites are drawn was developed to more accurately estimate the magnitude of the RTM effect. This function can be used to adjust CMFs that do not account for RTM, complementing the procedure developed and used to correct CMFs included in the HSM.

An experimental study of the forces generated by the collapse of transient cavities in water

1960 ◽  
Vol 7 (4) ◽  
pp. 596-609 ◽  
Author(s):  
I. R. Jones ◽  
D. H. Edwards
Keyword(s):  
Shock Wave ◽  
Experimental Study ◽  
Experimental Investigation ◽  
Peak Pressure ◽  
Surface Damage ◽  
Peak Force ◽  
Cavity Collapse ◽  
The Moment ◽  
Pressure Bar ◽  
Collapse Process

The paper describes an experimental investigation of the pressures developed at the seat of collapse of cavities in water. Single transient cavities, generated by a spark discharge, are allowed to collapse on the end of a piezoelectric pressure-bar gauge which measures the variation of thrust with time. It is shown that both the peak force and duration of the cavity collapse pulse are functions of the cavity lifetime. From an estimate of the minimum radius attained by the cavity and the peak force, the peak pressure on collapse is found to be at least 10,000 atm. Streak schlieren photographs of the collapse process show that a shock wave is radiated into the water at the moment of collapse and that the cavity rebounds. At the collapse of the rebound cavities the pressures developed are comparable with those developed by the collapse of the initial cavity, and these probably contribute materially to cavitational surface damage.

Should a Vehicle Always Deviate to the Tire Blowout Side? - A New Tire Blowout Model with Toe Angle Effects

2021 ◽  
Author(s):  
Ao Li ◽  
Yan Chen ◽  
Xinyu Du ◽  
Wen-Chiao Lin
Keyword(s):  
Road Safety ◽  
Experimental Results ◽  
Vehicle Stability ◽  
Ground Vehicles ◽  
Test Vehicle ◽  
Friction Forces ◽  
Toe Angle ◽  
Tire Forces ◽  
Tire Friction ◽  
First Time

Abstract As a severe tire failure, tire blowout during driving can significantly threaten vehicle stability and road safety. Tire blowout models were developed in the literature to conclude that a vehicle always deviates to the tire blowout side. However, this conclusion is proved to be inaccurate in this paper, since one important factor was largely ignored in the existing tire blowout models. Toe angle, as a basic and widely-applied setup on ground vehicles, can provide preset and symmetric lateral tire forces for normal driving. However, when tire blowout occurs, different toe angle setups can impact vehicle motions in different ways. For the first time, the toe angle is explicitly considered and integrated into a tire blowout model in this paper. For different tire blowout locations, driving maneuvers, and drivetrain configurations, the impacts of different toe angle setups on the variations of tire friction forces and vehicle motions are analyzed. The developed tire blowout model with toe angles is validated through both high-fidelity CarSim® simulation results and experimental results of a scaled test vehicle. Both simulation and experimental results show that a vehicle may not deviate to the tire blowout side, depending on the toe angle setups and driving maneuvers. Moreover, the experimental results also validate that the proposed tire blowout model can accurately evaluate the tire blowout impacts on vehicle dynamics.

Age and contraction type influence motor output variability in rapid discrete tasks

2002 ◽  
Vol 93 (2) ◽  
pp. 489-498 ◽  
Author(s):  
Evangelos A. Christou ◽  
Les G. Carlton
Keyword(s):  
Standard Deviation ◽  
Knee Flexion ◽  
Maximum Voluntary Contraction ◽  
Voluntary Contraction ◽  
Peak Force ◽  
Full Extension ◽  
Old Adults ◽  
Time To Peak ◽  
Impulse Duration ◽  
Young Subjects

The purpose of this study was to examine the ability to control knee-extension force during discrete isometric (IC), concentric (CC), and eccentric contractions (EC) in 24 young (mean age ± SD = 25.3 ± 2.8 yr) and 24 old (mean age ± SD = 73.3 ± 5.5 yr) healthy and active individuals. Subjects were to match a parabola with a time to peak force of 200 ms during IC, CC, and EC at six target levels of force [20, 35, 50, 65, 80, and 90% of the maximum voluntary contraction (MVC)]. ICs were performed at 90° of knee flexion, whereas CCs and ECs ranged from 90 to 80° of knee flexion (0° is full extension) at a slow velocity (25°/s). Results showed that subjects produced similar MVC forces for the three types of contractions. Young subjects produced greater MVC forces than old subjects, and within each age group, men produced greater force than women. The variability (standard deviation) of peak force and impulse in absolute values was greater for young compared with old subjects. When variability was normalized to the force produced [coefficient of variation (CV)], however, old subjects exhibited greater CV than young subjects for peak force and impulse. Both the standard deviation and CV of time to peak force and impulse duration were greater for the old adults. In general, ECs were more variable than ICs and CCs, and old adults exhibited greater CV compared with young adults during rapid, discrete ICs, CCs, and particularly ECs of the quadriceps.

scholarly journals Treasury Single Account Policy and Revenue Generation Among Federal Parastatals in Ekiti-State, Nigeria

2021 ◽  
Vol 12 (4) ◽  
pp. 156
Author(s):  
Oluyinka Ogungbade ◽  
Omowumi Olanike Oshatimi ◽  
Adebola Daniel Kolawole
Keyword(s):  
Standard Deviation ◽  
Federal Government ◽  
Government Policy ◽  
Road Safety ◽  
Empirical Studies ◽  
Descriptive Statistics ◽  
Revenue Generation ◽  
Paired Sample ◽  
Average Revenue ◽  
Inferential Analysis

Treasury Single Account (TSA) is a new government policy to fight corruption in the Nigerian public sector. The policy has received a lot of compliments from many Nigerians; however, empirical studies have produced mixed results. The study examined the effects of Treasury Single Accounts (TSA) on the revenue generation of federal government parastatals in Ekiti state. The study specifically examined the effect of TSA on revenue generation of Federal University Oye-Ekiti, Federal Teaching Hospital Ido, Federal Road Safety Commission Ado-Ekiti and Federal Polytechnics Ado-Ekiti. Both Descriptive and inferential statistics were used. The descriptive statistics include mean, standard deviation, minimum and maximum while the study employed paired sample t-test for inferential analysis. The study reveals that TSA has not enhanced the revenue generation among federal government parastatals in Ekiti state. The research further shows that TSA is counterproductive since average revenue generated after the implementation of TSA is lower than the average revenue that the parastatals generated before the implementation of TSA. The study recommends that the federal government of Nigeria should investigate the reasons why the TSA is counterproductive in Ekiti state and adequately monitor its implementation.

Crush Characteristics and Energy Absorption of Thin-Walled Tubes with Through-Hole Crush Initiators

2014 ◽  
Vol 606 ◽  
pp. 181-185 ◽  
Author(s):  
S. Kanna Subramaniyan ◽  
Arun Kumar Kananasan ◽  
Mohd Radzi Mohamed Yunus ◽  
Shahruddin Mahzan ◽  
Mohd Imran Ghazali
Keyword(s):  
Experimental Investigation ◽  
Energy Absorption ◽  
Static Loading ◽  
Absorption Capacity ◽  
Peak Force ◽  
Energy Absorption Capacity ◽  
Steel Tubes ◽  
Thin Walled ◽  
Through Hole ◽  
Initial Peak

An experimental investigation was conducted to compare the crush characteristics and energy absorption capacity of circular and square tubes with located through-hole crush initiator. Circular through-holes were fabricated at three different configurations based on location into steel tubes which had a length of 200 mm. Furthermore, two different side configurations along the tube were considered for introducing the crush initiators. The results found that adding crush initiator onto the tubes were effectively reduced the initial peak force of a thin-walled circular and square tubes under axial quasi-static loading. The peak crush force was reduced within a range 3-10% and 5-16% for circular and square tubes respectively when compared with corresponding tubes without crush initiator. Moreover, the energy absorption capacity of the tubes was independent with the incorporation of through-hole crush initiators. However, the energy absorption of circular and square tubes were slightly decreases when compared with the tubes fabricated four sided crush initiation and tubes without crush initiator. Overall, the effect of location and number of crush initiation proved significantly influences the initial peak forces while maintain the energy absorbed.

scholarly journals Regression to the mean correction for Collision Modification Factors

2021 ◽  
Author(s):  
Bernard James
Keyword(s):  
Standard Deviation ◽  
Road Safety ◽  
Relative Number ◽  
Highway Safety ◽  
Regression To The Mean ◽  
Simple Method ◽  
Highway Safety Manual ◽  
The Mean ◽  
Site Population

Collision Modification Factors (CMFs) are a simple method of representing the effectiveness of road safety treatments. With the release of the Highway Safety Manual (HSM) and the recent launching of a CMF Clearinghouse website, CMFs are likely to become more widely used for estimating the effects of potential road safety treatments. The presence of regression to the mean (RTM) bias has long been shown to affect the accuracy of CMFs that did not account for the RTM in their development. The purpose of this research was to study how the RTM depends on the number of years of data used for selecting high collision sites for treatment and on the relative number of sites selected. From this analysis, a function based on the number of years, percentage of high collision sites selected, and the mean and standard deviation of the site population from which the treated sites are drawn was developed to more accurately estimate the magnitude of the RTM effect. This function can be used to adjust CMFs that do not account for RTM, complementing the procedure developed and used to correct CMFs included in the HSM.

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