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Nomograms and graphs used for thermal radiation calculations
Published in Seán M. Stewart, R. Barry Johnson, Blackbody Radiation, 2016
Seán M. Stewart, R. Barry Johnson
An altogether different graph used for estimating the fractional function of the first kind for the radiometric case within finite spectral bands was given by V. I. Matveev in 1985 [430]. Concerned at the time with infrared vision devices, Matveev gave a figure that could be used to estimate the fractional amount radiated within the two principal atmospheric transmission bands in the infrared of 3.5–5 μm (midwave band) and 8–14 μm (longwave band) over terrestrial temperatures between −40°C to 100°C. Two curves were drawn; one for each spectral band. Selecting a temperature on the abscissa, to find the fractional amount a vertical line is drawn. Its intersection with the midwave band curve, the ordinate to the left is read, while for the longwave band curve, the ordinate to the right is read.
Recent Trends in Adaptive Control Applications
Published in V. V. Chalam, Adaptive Control Systems, 2017
Karnik and Sinha [101a] discuss the application of robots for arc welding processes and consider the problems encountered and different approaches for solving the same. The quality of the weld joint depends on (1) shape and local variation of the seam to be welded, (2) relative position of the welding arc and the joint, (3) arc length, (4) shape and size of the molten weld pool, and (5) position of the arc center relative to the pool. The primary objective of the positional control of the robot arm is to ensure that the path traced by the robot arm is exactly on the seam of the two workpieces. The position of the seam can be sensed by three principal methods, namely, (1) arc sensing, (2) tactile or proximity sensors, and (3) vision or scanning sensors. The last method is the most popular since it is noncontacting and does not require weaving. From the coordinates of the end point obtained from the sensors, signals required for the motors are evaluated and applied. However, the end point of the robot arm does not usually coincide with the desired location because of several factors. For acceptable welding, this positional error should be minimized so that welding is done properly on the seam. Several approaches to compensate for positional error along with their merits and demerits are discussed. Among these, it is shown that the self-tuning regulator, signal-synthesis MRAC, and vernier robot approach are most suitable for the control of the robot arm. The time between the updates depends on the speed of welding, which in turn depends on the type of material, type of joint, and so on. A discussion on the choice of the appropriate microprocessors for implementing the adaptive controller is presented. Details are given of the modified UNIMATE 2000 robot, which has five degrees of freedom. The movement of the robot is achieved by applying the required voltages to the motors corresponding to each axis. The desired position of the gun is the input to the master controller which evaluates the voltages required by the individual motors to attain the position. Each of the five slave controllers receives data from the encoder, closes the positional loop, and controls the acceleration, velocity, and position of the servo for the corresponding axis. Also see the papers by Cook et al. [101b], who consider microcomputer control of an adaptive positioning system for robotic arc welding and Begin and Boillot [101c], who discuss infrared vision applied to adaptive welding.
A system dynamics-based approach for risk analysis of waterway transportation in a mixed traffic environment
Published in Maritime Policy & Management, 2023
Chengpeng Wan, Yinxiang Zhao, Di Zhang, Liang Fan
The perception stage is the stage of inputting information. This stage collects the information on navigation environments and ships through sensing equipment. A remote-control ship mainly uses solid-state radar, laser radar, panoramic infrared vision, sound recognition, remote sensing, 3D reconstruction of digital scenes, and multimedia technologies to sense ship navigation environments and obtain the necessary navigation data. The data includes ship information and environmental information. In addition to the traditional detection instruments (such as radar and electronic sea maps), conventional ships can also obtain information of surrounding environment through crew.