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Water Hydraulics
Published in Frank R. Spellman, Handbook of Water and Wastewater Treatment Plant Operations, 2020
Water exerts force and pressure against the walls of its container, whether it is stored in a tank or flowing in a pipeline. Force and pressure are different, although they are closely related. Force is the push or pull influence that causes motion. In the English system, force and weight are often used in the same way. The weight of a cubic foot of water is 62.4 lb. The force exerted on the bottom of a one-foot cube is 62.4 lb. If we stack two cubes on top of one another, the force on the bottom will be 124.8 pounds. Pressure is a force per unit of area. In equation form, this can be expressed as: P=FA
Introduction and Background
Published in Kazuhisa Miyoshi, Solid Lubrication Fundamentals and Applications, 2019
The technical function of numerous engineering systems, such as machines, instruments, and vehicles, depends on processes of motion. According to its basic physical definition the term “motion” denotes the change in the position of an object with time. Many processes in nature and technology depend on the motion and the dynamic behavior of solids, liquids, and gases (Table 1.1, [1.3, 1.4]). For example, bearings and gears permit smooth, low-friction rotary or linear movement between two surfaces (Fig. 1.2). Bearings employ either sliding or rolling action and gears have both sliding and rolling action. In these cases a strong attempt is made to provide enough lubrication to keep the bearing and gear teeth surfaces separated by a film of solid lubricant, oil, or other lubricant such as grease. The absence of physical contact provides most bearings and gears with long service lives.
Mechanical Structure Including Mechanisms and Load Analysis
Published in Seong-woo Woo, Design of Mechanical Systems Based on Statistics, 2021
A variety of mechanisms in automobiles, refrigerators, bicycles, etc. are a mechanical portion that can transfer motion and forces from a power source to the other. Most mechanisms are designed to provide a mechanical advantage. They also form a kinematic chain in which at least one link is attached to a frame of reference (ground) and makes four different motions, namely, rotary motion, oscillation, linear motion, and reciprocating motion. Rotary motion is the starting point for many mechanisms, mostly provided by an engine or dc motors. Oscillation is a back and forth motion about a pivot point. Linear motion is a one-dimensional motion along a straight line. Reciprocating motion is again a back and forth motion.
Investigation of Transient Stability in Power System with Improved FRT Capable Solar PV Inverters
Published in Electric Power Components and Systems, 2023
C. Nithya, J. Preetha Roselyn, D. Devaraj
The main reason behind the stability of power system and making it rigid is due to rotational inertia of synchronous machines. The tendency of an object to remain in motion and keep the system operating for a certain time is known as inertia. During steady state conditions, the supply of power from all the generators meets the demand and the frequency remains constant. If there is a generator loss in the power plant, the power will drop instantly. As the demand remains the same, the energy is provided from the inertia of the generators and hence the frequency is constant. The governor of power system detects changes in frequency and regulates system to increase/decrease the speed. But this control action will take some time to act in the generators. During this time, stored kinetic energy of synchronous machines is supplied to meet the demand. When the power system is integrated more with inverter fed PV systems, this rotational kinetic energy is reduced and hence inertia of the power system is reduced. To address this issue without affecting the power grid reliability, a FRT capable solar PV system is integrated into the power plant.
Skin-textiles friction: importance and prospects in skin comfort and in healthcare in prevention of skin injuries
Published in The Journal of The Textile Institute, 2021
Ruksana Baby, Kavita Mathur, Emiel DenHartog
Friction is a surface property defined as the tangential force that opposes relative motion when one body slides over another (Gupta, 2008). It is an essential part of all physical phenomenon in daily life that works in many different forms, including but not limited to, the force we exert in performing mechanical work, electrical power and fuel we use in running equipment, the wear damage we find on surfaces, the temperature rise we observe in materials and devices during use, and the sound we hear in most industrial and non-industrial operations. Friction in textiles has been studied as it affects the efficiency of processing, mechanical integrity and dimensional stability of assemblies, wear of textiles and guides, and tactile comfort and drape of apparel. This section will provide an understanding of relevant friction theories for textile materials and how factors associated with textiles impact the frictional characteristics of textiles in performance or end-use.
Slip safety risk analysis of surface properties using the coefficients of friction of rocks
Published in International Journal of Occupational Safety and Ergonomics, 2019
Gültekin Çoşkun, Gencay Sarıışık, Ali Sarıışık
Studies aiming to reduce accidents due to slipperiness have increased as a result of increasing numbers of pedestrian slipping accidents [23]. The importance of surface roughness (SR) in slip resistance (SLR) measurements and its role as one of the factors determining optimal material and floor covering have been emphasized in many studies since 1988 [24–30]. The SLR depends on friction, and SR has an effect on friction. Friction is the resistance to relative motion between two bodies in contact with each other. These bodies are the slider and test specimens, or the base of the shoe and the surface upon which it is moved. Friction force is the force acting tangentially in the contact area [31–34]. Determining the role of SR on friction can benefit floor producers and designers. Increase of SR increases the SLR of floor covering, thereby reducing slipperiness [35–37]. Note that every surface has some degree of roughness, although the scale of the roughness might be microscopic [38].