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Vehicle Mechanics
Published in Iqbal Husain, Electric and Hybrid Vehicles, 2021
The fundamentals of a vehicle design are embedded in the basic mechanics of physics, particularly in Newton’s second law of motion relating force and acceleration. Newton’s second law states that the acceleration of an object is proportional to the net force exerted on it. The object accelerates when the net force is non-zero, where the term net force refers to the resultant of the forces acting on the object. In the vehicle system, several forces act on it with the resultant or net force dictating the motion according to Newton’s second law. A vehicle propels forward with the aid of the force delivered by the propulsion unit overcoming the resisting forces due to gravity, air and tire resistance. The acceleration and speed of the vehicle depend on the power available from the traction unit and the existing road and aerodynamic conditions. The acceleration also depends on the composite mass of the vehicle including the propulsion unit, all mechanical and electrical components and the batteries.
Single-Phase Flow in Nuclear Power Plants
Published in Robert E. Masterson, Nuclear Reactor Thermal Hydraulics, 2019
Bernoulli’s equation is one of the most important equations in all of fluid mechanics. Holistically speaking, Bernoulli’s equation is based on Newton’s laws of motion applied to a fluid in motion: Newton’s first law: If an object experiences no net force, then its velocity is constant. The object is either at rest (if its velocity is zero), or it moves in a straight line with constant speed (if its velocity is nonzero).Newton’s second law: The acceleration a of a body is parallel and directly proportional to the net force F acting on the body. The acceleration is in the same direction as the net force, and it is inversely proportional to the mass m of the body, that is, F = ma.Newton’s third law: When a first body exerts a force F1 on a second body, the second body simultaneously exerts a force F2 = −F1 on the first body. This means that F1 and F2 are equal in magnitude and opposite in direction. In other words, for each reaction, there is an equal and opposite reaction.
Measurement of Electrolytic Conductance
Published in Grinberg Nelu, Rodriguez Sonia, Ewing’s Analytical Instrumentation Handbook, Fourth Edition, 2019
Stacy L. Gelhaus, William R. LaCourse
A cation responds to the application of the field by accelerating toward the negative electrode, and an anion responds by accelerating toward the positive electrode. As the ion moves through, the solvent experiences a frictional resisting force, Ffric, proportional to its speed.6 The two forces act in opposite directions, and the ions reach a terminal speed, the drift speed (s), when the accelerating force is balanced by the viscous drag. The net force is zero when s=zeEf
A survey: dynamics of humanoid robots
Published in Advanced Robotics, 2020
Tomomichi Sugihara, Mitsuharu Morisawa
(A) is validated when the robot is in the air or supported only by a point or an edge. This is the strongest natural constraint since the robot behavior is ruled by this regardless of control. (B) is also a natural constraint but has a certain degree of tolerance due to backlashes or elastic deformations of body parts. Regarding (C), the contact points are not strictly constrained but might accept slight sliding on and detaching from the environment, though it is not desirable. (D) is an artificial constraint and is associated with the net force/torque that has to be consistent with the contact condition. It also has a tolerance depending on the supporting region. Allocation of contact points and manipulation of the net contact force are mutually dependent as seen in Section 4, and thus, their priorities are occasionally turned over. Nevertheless, they are less prioritized than (A) and (B). The remaining (E) is artificially given based on the task to be achieved and affects the performance of task executions. Though it is less prioritized than the physical security of the robot in many cases, there can be extreme situations where the robot has to accomplish tasks even by losing its balance, e.g. to catch a falling object by diving to it. Hence, the priority (E) compared to (C) and (D) depends on the context.
Fire extinguishment using a 4 m long flying-hose-type robot with multiple water-jet nozzles
Published in Advanced Robotics, 2020
Hisato Ando, Yuichi Ambe, Tomoka Yamaguchi, Yu Yamauchi, Masashi Konyo, Kenjiro Tadakuma, Shigenao Maruyama, Satoshi Tadokoro
The vector of the net force at the center of the nozzle module i is represented by , and the torque at the detection point of the force sensor is represented by . The reaction force owing to a single jet nozzle is defined as . Therefore, the reaction force acting on the ith nozzle module is expressed using the following equation: Each torque component acting on the nozzle module is expressed using the following equations: As shown in Figure 4, the distances between the detection point and the center of the swinging axis for the pitch and roll directions are defined as and , respectively, and the length of the tube is defined as . The moment arms and are expressed by using the following equations:
Acceleration statistics of prolate spheroidal particles in turbulent channel flow
Published in Journal of Turbulence, 2018
Rafik Ouchene, Juan Ignacio Polanco, Ivana Vinkovic, Serge Simoëns
Particle acceleration is directly related to the net force the particle experiences along its trajectory. This aerodynamic force depends on particle shape and orientation when the particles are non-spherical. Therefore, shape effects on acceleration statistics are investigated here to understand the dynamics of non-spherical particles in turbulent flows. To our knowledge, only Njobuwenwu and Fairweather [22] reported the PDFs of the normalised wall-normal spheroidal particle acceleration at two wall distances, in the channel centre and the buffer region. The authors used large-eddy simulations at a friction Reynolds number of coupled with Lagrangian tracking of needle- and platelet-like particles in a turbulent channel flow. In the case of oblate and prolate particles with respective aspect ratios and 10 and an equivalent Stokes number of St=125, the authors found that the tails of the wall-normal acceleration PDFs are not significantly affected by shape compared to the spherical case, although differences may occur at the peak value.