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Equations of motion
Published in Mohammad H. Sadraey, Aircraft Performance, 2017
In terms of speed, one knot is equal to one nautical mile per hour. For cars and trains, statute mile is used in the United States, since statute mile is different from nautical mile. Relationships between various units of speed are as follows: Knot=Nautical mileHour
Air pollution modelling
Published in Abhishek Tiwary, Ian Williams, Air Pollution, 2018
Wind speed is measured in m s−1 or knots (one knot is one nautical mile per hour; one nautical mile is 6080 ft, or 1.15 statute miles). Although the use of SI units is encouraged in all scientific work, some professions have stuck with earlier systems. Thus mariners, pilots and meteorologists are all comfortable with knots. Mariners also use the Beaufort Scale, which relates wind speed to its effects on the sea.
Overview and introduction
Published in Tom Denton, Automobile Mechanical and Electrical Systems, 2018
Velocity is the speed of an object in a given direction. Velocity is a ‘vector quantity’, meaning that its direction is important as well as its speed. The velocity v of an object travelling in a fixed direction may be calculated by dividing the distance s it has travelled by the time taken t. It is expressed as miles per hour (mph) or m/s (metres per second).
Biomechanical effects of a halo orthotic on a pediatric anthropomorphic test device in a simulated frontal motor vehicle collision
Published in Traffic Injury Prevention, 2022
Eric A. Sribnick, Julie A. Mansfield, Carrie Rhodes, Vera Fullaway, John H. Bolte
Kinematics were recorded using high speed video (1000 frame/s) and analyzed using TEMA Motion software (v3.8, Image Systems AB, Linköping, Sweden). Sample video from all tests are available as Appendix C. Head and knee displacement data were calculated from the initial position of each test. Biomechanical data were obtained from the ATD from the following instrumentation: head and chest accelerometers (Meggitt Sensing Systems, Irvine, CA), head angular rate sensors (Diversified Technical Systems, Seal Beach, CA), a six-axis upper neck load cell (Humanetics), and chest linear potentiometer (Servo Instrument Corporation, Baraboo, WI). Data from ATD channels were processed in accordance with Society of Automotive Engineers (SAE) J211 guidelines (SAE International 2007). For analysis of the resulting forces, biomechanical injury thresholds are shown as a reference (Mertz et al. 2016). Sled acceleration is reported as standard gravity (g), and sled velocity is reported as miles per hour (mph). Metrics of sled pulses are reported as mean plus/minus standard deviation, and coefficient of variation (CV) is also reported. Statistical analysis was performed using GraphPad Prism (version 8.2, San Diego, CA).
Quantifying greenhouse gas emission of asphalt pavement preservation at construction and use stages using life-cycle assessment
Published in International Journal of Sustainable Transportation, 2020
Hao Wang, Israa Al-Saadi, Pan Lu, Abbas Jasim
The life-cycle impact of pavement preservation on emission was analyzed for different treatments as compared to the control pavement section (do-nothing scenario). At the current stage of analysis, it is assumed that only one preservation treatment is applied before IRI reaches the terminal value. The study assumed that there is no treatment before the pavement is three years old because pavement condition is good at the beginning and there is no need for preservation. After that, pavement preservation treatment can be applied one time at any year before IRI reaches the terminal value. Since the pavement section with preservation treatment reaches the terminal IRI value at a later time, the IRI at control pavement section is kept unchanged after reaching the terminal IRI value in order to have the same analysis period between control section and treatment sections. The initial and terminal IRI values were set to be 1.0 m/km and 2.714 m/km for the reference case, respectively. It is assumed that average annual daily traffic (AADT) is 15,000 and the percentages of passenger car, passenger truck, and combination long-haul truck in the traffic stream are 45%, 45%, and 10%, respectively. Assuming that combination truck has truck factor of 1.0, the AADTT in ESALs will be 1500 for the reference case. The analysis was conducted for one lane-mile asphalt pavement segment with speed limit of 65 mph.
A network design problem formulation and solution procedure for intercity transit services
Published in Transportmetrica A: Transport Science, 2020
Andisheh Ranjbari, Mark Hickman, Yi-Chang Chiu
As a note, we tried = 4.47, but since the TPTT term dominates over the DT term in the objective function, and the latter consists of a very small fraction of the objective function value, the solutions found with = 4.47 were the same as when = 1. The value of = 4.47 was calculated as follows. Considering $30 per hour for labor cost (including wage and fringe benefits) (Kay et al. 2011), $0.7 per mile for energy and maintenance cost for battery electric buses (USDOT FTA 2017), and an average speed of 78.5 mph for Flexpress (150 mph on the high-speed section and 20 mph in the urban areas), the operating cost would be $85 per hour: 0.7*78.5 + 30 = 85. Assuming a $19 per hour value of time for passengers (USDOT 2015), = 85/19 = 4.47. The solution times with = 4.47 were higher than those with = 1 (between 1.2 and 5 times higher), but the solutions were the same. So, what is reported in the next section are the outputs of model runs with = 1.