China
Africa
Explore chapters and articles related to this topic
Solar Power Fields
Published in Anco S. Blazev, Solar Technologies for the 21st Century, 2021
There are a number of materials in the PV module that act and interact differently with adjacent materials, depending on temperature, pressure and other factors. The major mechanical forces determining the interaction between the different layers in the module are: Coefficient of friction is the force that resists the lateral motion of solid surfaces in contact with each other and moving in different directions. This includes the types of materials (substrates and layers of materials stacked on top of each other) of which PV modules are made.Coefficient of thermal expansion (linear and volumetric) is the way different materials expand and shrink under different temperature gradients. In other words, all materials tend to change shape and size along the surface and across their volume, with changes in temperature, which ultimately results in mechanical friction if in contact with other materials.
Crystalline Silicon Photovoltaic Technologies
Published in Anco S. Blazev, Photovoltaics for Commercial and Utilities Power Generation, 2020
There are a number of materials in the PV module that act and interact differently with adjacent materials, depending on temperature, pressure and other factors. The major mechanical forces determining the interaction between the different layers in the module are: Coefficient of friction is the force that resists the lateral motion of solid surfaces in contact with each other and moving in different directions. This includes the types of materials (substrates and layers of materials stacked on top of each other) of which PV modules are made.Coefficient of thermal expansion (linear and volumetric) is the way different materials expand and shrink under different temperature gradients. In other words, all materials tend to change shape and size along the surface and across their volume, with changes in temperature, which ultimately results in mechanical friction if in contact with other materials.
Slip-and-Fall Accidents
Published in Randall Noon, Introduction to Forensic Engineering, 2020
The coefficient of friction is defined as the ratio of the force needed to overcome the friction to the force perpendicular to the contact surface. For example, if the box weighs 200 pounds, and it takes 75 pounds of force directed parallel to the floor to "break it loose" and get it going, then the COF between the box and the floor is COF=frictional force/weight
Robust indirect adaptive control of electromechanical servo systems with uncertain time-varying parameters
Published in International Journal of Control, 2023
Xiao Chen, Wenxiang Deng, Jianyong Yao, Xianglong Liang, Zhendong Zhang
In practice, the friction coefficient B and Af are varying. Temperature, lubrication, wear of materials, position changes, and other factors may influence the friction coefficient in a very complicated way. Hence, the friction parameters are marked as B(t), Af(t). Moreover, the unstructured uncertainties can be split as , where dn(t) is the low-frequency part that can be estimated by adaptive law and is the remainder. In this paper, the uncertain friction coefficients and part of unstructured uncertainties are captured by indirect adaptive law. Thus, we define the unknown parameter vector as .
Proposed Modification for ADAS Damper to Eliminate Axial Force and Improve Seismic Performance
Published in Journal of Earthquake Engineering, 2022
Mohammadreza Khoshkalam, Mohamad Hosein Mortezagholi, Seyed Mehdi Zahrai
The coefficient of friction will include two types, static, and dynamic, the static type of which is always greater than the dynamic one. The direction of the force created at these points is due to the fact that rolling friction (related to static friction coefficient) dominates sliding friction (related to dynamic friction coefficient). So that the bars begin to roll within the slits rather than slide (like the movement of car wheels on a normal road) and cause a significant tensile force in MADAS plates. The interaction of the tensile force created by the moment will increase the shear force level and an abrupt jump will be observed in the diagram. But in areas where the shear force growth is almost constant in the diagram, the deformation of damper and combination of forces provide bars with conditions for sliding through the slits (like the slipping of cars on a frozen road when the wheels are locked) and as a result, the tensile forces in plates decline significantly. This mechanical behavior is of the contact type and it is necessary to evaluate experimental behavior in the future research for more detailed results. Yielded areas of triangular plates are shown in Fig. 12. Obviously, a uniform yielding occurs throughout the plates. According to Fig. 11, three zones may be defined to determine the maximum shear force produced by the damper and the appropriate shear force can be used given the prediction of maximum possible displacement in the damper.
Experimental study on lubrication performance of main components of biodiesel
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2022
Yonghui Wu, Fashe Li, Wenchao Wang, Zihao Ni, Baoping Ding, Huicong Zhang
Coefficient of friction is the ratio of the friction between the two surfaces and the vertical force applied to the surface (Liang et al. 2019). The length of the saturated ester-based chain had influence on its friction coefficient (as shown in Table 5). Methyl palmitate has the maximum average friction coefficient of 0.13. As the alkyl chain length increased, the average coefficient of friction esters (palmitate and stearate esters) decreased gradually. The minimum average coefficient of friction amyl palmitate and amyl stearate was 0.02, while amyl stearate had the smallest wear spot diameter and the best lubricity. Figure 7 uses palmitic acid esters as an example to show the changes of friction coefficients of five kinds of esters during friction and wear. The palmitate ester with biggest coefficient of friction was methyl palmitate, followed by ethyl palmitate, propyl palmitate, butyl palmitate, and amyl palmitate. The friction coefficients of stearates varied in the same trend.