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Conceiving Design Solutions
Published in Bahram Nassersharif, Engineering Capstone Design, 2022
As an example of engineering error, in 1999, NASA lost its Mars Climate Orbiter because the engineers failed to perform a unit conversion from engineering units to metric when communicating the critical spacecraft data before launch. The error cost NASA the $125 million spacecraft. The navigation team at NASA’s Jet Propulsion Laboratory (JPL) used millimeters and meters in their calculations. At the same time, design engineers at Lockheed Martin Aeronautics in Denver provided acceleration data in feet and pounds. Lockheed Martin was responsible for the design and build of the orbiter spacecraft. JPL engineers assumed the acceleration data was provided to them in Newton-seconds. A simple error cost the mission years of setback, and much hard work was lost. SI units, also known as the metric system, are the international standard for communicating science, engineering, and technical data.
Mechanical, electrical and trim – MET
Published in Andrew Livesey, Alan Robinson, The Repair of Vehicle Bodies, 2018
SI stands for System International, a system of measurement units which was developed following World War II. There are several different systems in use throughout the world, but for your examinations with UK-based examining bodies, SI only is used. It is worth noting that countries such as Germany and Japan use SI but with amendments and modifications. The Germans use DIN – Deutsch (Germany) Industrial Norm. The Americans use ANSI – American National Standards Institute – as well as SI. We’ll also discuss some of the others, as they are used in America too. The Imperial System – so-called after the British Empire – is now known as the British Commonwealth, although it is very different now in how it operates.
Science terminology
Published in Andrew Livesey, Bicycle Engineering and Technology, 2020
SI stands for System International, a system of measurement units which was developed following World War II. There are several different systems in use throughout the World, but for your examinations with UK based examining bodies, SI only is used. It is worth noting that in countries such as Germany and Japan, they use SI, but with amendments and modifications. The Germans use DIN—Deutsch (Germany) Industrial Norm. The Americans use ANSI—American National Standards Institute, as well as SI. We'll also discuss some of the others as they are used in America too. The Imperial System—so called after the British Empire of the Victorian era.
Accurate nanoparticle size determination using electrical mobility measurements in the step and scan modes
Published in Aerosol Science and Technology, 2022
Kaleb Duelge, George Mulholland, Michael Zachariah, Vincent A. Hackley
Nanoparticle “size,” typically a method-defined measurement and frequently based on the diameter of an equivalent sphere, is an important characteristic that impacts particle transport properties, such as mobility, diffusion, friction, coagulation, and charging. Size also plays an important role in optically active materials and is a critical factor in biodistribution. It is therefore important to accurately measure the size of nanoparticles, which is why size standards are relied on heavily in research and industry. A common method for certifying standards in industry is based on electron microscopy (Particle Technology Technical Notes and Reference Guide – Strategies and Procedures for Bead Optimization 2018). In some cases, the known and unknown particles are mixed and deposited together on a microscope grid. Well-characterized methods, such as light scattering (Mulholland et al. 1985), the calibrated atomic force microscope of the National Institute of Standards and Technology (NIST) (Dixson et al. 1999), and electro-gravitational aerosol balance (Takahata, Sakurai, and Ehara 2020), where the key uncertainty terms have been calculated, can be used for primary certification. It is also ideal for a method to be traceable, where a direct connection is made to an international system of units (SI): most often the meter, but potentially the kilogram if particle mass or volume and density are determined.
Enhanced ferroelectricity for nanoporous barium titanate: a phase-field prediction
Published in Philosophical Magazine Letters, 2021
Chengmin Xie, He Zhao, Lifei Du, Huiling Du, Pingping Wu
BaTiO3 is taken as the aim material in this work. The corresponding coefficients in our simulation are [24]: α1 = 4.124(T - 388) × 105, α11 = −2.097 × 108, α12 = 7.974 × 108, α111 = 1.294 × 109, α112 = −1.905 × 109, α123 = 2.500 × 109, α1111 = 3.863 × 1010, α1112 = 2.529 × 1010, α1122=1.637 × 1010, α1123 = 1.367 × 1010, C11 = 1.78 × 1011, C12 = 0.964 × 1011, C44 = 1.22 × 1011, Q11 = 0.10, Q12 = −0.034, Q44 = 0.029. For simplify, the kinetic coefficient Lp and Lη are chosen to be 1.0. All the units for the parameters are in SI unit and T is in Kelvin. Room temperature of 298.15 K is used in our current simulation.
Application of exergy and entransy concepts to analyses performance of coal fired thermal power plant: a case study
Published in International Journal of Ambient Energy, 2021
The exergy rates for FWHs were calculated as Here Ws and Ww are mass flow rates of steam and cold water in kg/s. Cps and Cpw are specific heats of steam and water in kJ/kg-K. Tsi and Tso are inlet and outlet temperatures of steam in Kelvin. Two and Twi are outlet and inlet temperatures of water in Kelvin respectively, T0 is ambient temperature which was assumed as 301 K and ϕdes is exergy destruction (ExD) in kW. Term entransy, which is used in recent era to analyse the performance of HEx, can be defined as the ability of heat transfer from a HEx and this new term can be understand by analogy between electrical and thermal parameters as in Table 3 (Guo, Zhu, and Liang 2007; Ahmadi and Toghraie 2015; Ahmadi and Toghraie 2016; Ahmadi et al. 2017; Ahmadi, Toghraie, and Akbari 2017b; Geete 2019; Malakar and Geete 2018; Geete 2017a; Geete 2017b; Geete et al. 2017d).