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Maxwell’s theory of electromagnetism
Published in Edward J. Rothwell, Michael J. Cloud, Electromagnetics, 2018
Edward J. Rothwell, Michael J. Cloud
along the helix axis. This distance p is called the pitch of the helix. The pitch angleα $ \alpha $ is the angle made between the direction of motion and the ab-plane, or tanα=p2πrc=v‖ωcrc=v‖v⊥. $$ \tan \alpha = \frac{p}{2\pi r_c} = \frac{v_\parallel }{\omega _c r_c}=\frac{v_\parallel }{v_\perp }. $$
Fabrication Processes
Published in Manas Chanda, Plastics Technology Handbook, 2017
The screw consists of a steel cylinder with a helical channel cut into it (Figure 2.18). The helical ridge formed by the machining of the channel is called the flight, and the distance between the flights is called the lead. The lead is usually constant for the length of the screw in single-screw machines. The helix angle is called pitch. Helix angles of the screw are usually chosen to optimize the feeding characteristics. An angle of 17.5° is typical, though it can be varied between 12 and 20°. The screw outside diameter is generally just a few thousandths of an inch less than the ID of the barrel. The minimal clearance between screw and barrel ID prevents excessive buildup of resin on the inside barrel wall and thus maximizes heat transfer.
Power Screws
Published in Keith L. Richards, Design Engineer's Sourcebook, 2017
Helix Angle θ: The helix angle is the angle that is made by the thread with a line drawn perpendicular to the centerline of the thread. It is also the slope of the inclined plane if the helix were unwrapped and laid on a flat surface. It is given by: tanθ=Lπd
Study on the stability for non-uniform helix angle tools in the milling process
Published in Journal of Industrial and Production Engineering, 2020
Qiang Guo, Ming-Yang Zhang, Yuan-Shin Lee, Zhi-Bo Yang, Yan Jiang, Cong-Hui Feng
Firstly, the non-uniform helix angle is closely related to the variable pitch angle. Earlier studies proposed that the “Regeneration factor” (RF) affects the chatter suppression under an arbitrary vibration frequency. The RF is controlled by the regeneration process. It is calculated by dividing each flute along the axial direction into small elements. The non-uniform helix and pitch angle can decrease the value of RF. On the other hand, the regenerative effect is positively correlated with the RF value. Accordingly, decreasing the value of RF can reduce regeneration and increase stability. Thus, when RF = 0, regeneration or chatter is completely suppressed.
Enhancement of surface temperature distribution of solar receiver tube using coil winding
Published in International Journal of Ambient Energy, 2020
The helix angle is defined as the angle between any helix and an axial line on its right, circular cylinder or cone. In this paper, the helix angle is 82°. The pitch of a helical coil is defined as the distance from centre to centre of two adjacent coils. The pitch for this case is calculated as 68.5 mm. Here, from the equation of total length of wounded coil it is found to be 6.2 m. The properly designed helical coil used for wounding the straight solar receiver tube in this experiment is shown in Figure 1.
Broadband reflection prepared by loading chiral dopants in white carbon black
Published in Liquid Crystals, 2021
Fangfang Li, Yuzhen Zhao, Hong Gao, Dong Wang, Zongcheng Miao, Hui Cao, Zhou Yang, Wanli He
Cholesteric liquid crystals are of great interest for many applications, due to the unique optical characteristics. Examples include reflective colour displays, fibre optic communications, integrated highways, biosensors, laser radiation, tunable light–reflector, tunable metamaterial absorber [1–3], and so on. Among these optical characteristics, the selective reflection characteristics of cholesteric liquid crystals have the widest application range [4,5]. For example, the reflected light range is in the visible light range, which can be used in e-books, liquid crystal display panel light enhancement films, etc. On the other hand, cholesteric liquid crystals with a wide reflection band in the infrared range can be used in the field of building energy conservation and laser protection devices. There are two ways to form cholesteric liquid crystals (ChLC). One is that the molecule itself contains chiral carbon atoms, the other is the incorporation of chiral dopant in the nematic liquid crystal [6–8]. The effect can be tuned to practically any spectral regions in UV, visible and IR by chiral additives of different twisting power or concentrations. By doping different types and concentration of chiral dopant, the pitch P of the chiral nematic liquid crystal will have different effects. The pitch was defined as the length of one complete rotation of the helix. According to the Bragg reflection formula: Δλ = Δn × P, Δλ is the reflection bandwidth of selective reflection of cholesteric liquid crystal, Δn is the birefringence of cholesteric liquid crystal. Since the birefringence Δn of cholesteric liquid crystal is generally less than 0.4 [9–13]. The single-pitch cholesteric liquid crystal selectively only reflects the narrow bandwidth, which limits its practical application in life. It is difficult to adjust the reflected bandwidth by adjusting Δn, so it is necessary to adjust the pitch gradient or make the pitch non-uniform pitch distribution in order to widen the reflection bandwidth [14–17].