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Published in Samuel C. Sugarman, HVAC Fundamentals, 2020
temperature sensor: (Control) A control component to sense a change in temperature. There are various types of temperature sensing elements for pneumatic and electrical/electronic systems. See Chapter 10. Thermal expansion elements such as bimetal or metal rod and tube elements, and vapor or liquid-filled elements such as sealed bellows, remote bulb or capillary fast response or averaging elements. Bimetal elements are commonly used in room thermostats. Rod and tube elements are generally used in insertion and immersion temperature controllers, such as those located in boilers or storage tanks. Sealed bellows elements are commonly used in room thermostats. Remote bulb elements are used where the temperature measuring point is a distance from the controller location, such as in a duct or pipe. Fast response and averaging capillary elements are used instead of the bulb in a remote bulb element. The fast response element is a tightly coiled capillary with a response time many times faster than the standard remote bulb. The averaging element is a capillary evenly strung across a duct to obtain the average temperature in the duct. Change of temperature can be sensed with changes in electrical resistance (thermistor) or voltage (thermocouple).
B
Published in Philip A. Laplante, Comprehensive Dictionary of Electrical Engineering, 2018
where x is the state vector, u the control vector with components u i , i = 1, 2, . . . , m, A, B, Di are matrices of the appropriate dimensions. See also population dynamics. bilinear interpolation interpolation of a value in 2-D space from four surrounding values by fitting a hyperbolic paraboloid. The value at (x, y), denoted f (x, y) is interpolated using f (x, y) = ax +by +cx y +d, where a, b, c and d are obtained by substituting the four surrounding locations and values into the same formula and solving the system of four simultaneous equations so formed. bilinear transformation (1) conformal mapping of the complex plane of the form f (z) = az + bcz + d, where the real values a, b, c, d satisfy ad - bc = 0. Also called linear fractional transformation or Mübius transformation. o (2) a special case of (1) is a mapping from the j axis in the s-plane to the unit circle |z| = 1 in the z-plane, given by x = 2T 1 - z -1 1 + z -1 , where T is the time interval between samples. Such bilinear transformations are used in the design of recursive digital filters from equivalent analogue filters in the following procedure: · define characteristic digital frequencies i . · prewarp these to analog frequencies i using 2 i i = T tan 2T ; 1 i k. · design a suitable analog filter with frequencies i . · use the bilinear transformation to replace s 2 1-z -1 in the analog filter with s = T 1+z -1 . bimetal overload device an overload device that employs a bimetal strip as the actuating element. The bimetal strip consists of two metals bonded together. When heated, the bimetal strip will bend due to the different coefficients of linear
E
Published in Splinter Robert, Illustrated Encyclopedia of Applied and Engineering Physics, 2017
[computational, electromagnetism, general] The amount of work needed to transport a positive electric charge of 1 C from infinity to the point of electric interest. When a cumulative charge is located at this point then work is performed, otherwise no work is performed and no electric potential exists in this point. In case an artificial potential difference is maintained between two points, a galvanic mechanism needs to maintain a current from the higher electric potential to the lower electric potential, note current is the flow of charge. An electric potential can, for instance, be generated by means of the photoelectric effect, using electromagnetic radiation to release electrons from their atomic/molecular orbit and hence providing the mechanism of action (the work) to create a potential difference. Other means involve making surface contact between two or more metals (bimetal). The metal-plate electric potential series is a function of both the nature of the metals and the localized temperature. The electric potential exists under the condition of no current (also seebatteryandthermocouple). Animals such as the electric eel and electric manta-ray create a high electrical potential by chemical means, reaching several hundred volt. A similar electrochemical process is used in nerves and muscle cells (seeNernst potential) for signal propagation by electrical potentials and muscle contraction.
Investigation wavy interface forming and stretching in severe plastic deformed copper/steel bimetallic rod
Published in Mechanics of Advanced Materials and Structures, 2021
The main challenge in the preparation of bimetal materials is weak bonding between the contacted surfaces of two dissimilar metals. In systems like copper/steel bimetal composite, the metallurgical bonding is hindered because they form an immiscible binary system. As a result, mechanical adhesion with low strength is obtained during copper-clad steel preparation by conventional methods. To improve the interfacial bonding strength of bimetallic materials, one beneficial way is the use of SPD processes. Eivani and his colleague [15] indicated that the interfacial bonding strength of copper clad aluminum subjected to two passes of equal channel angular extrusion was 12.5% higher than that samples produced by general extrusion process. According to the work of Shen et al. [16], it is possible to achieve metallurgical bonding between copper clad and substrate steel using the FSW process. In addition to the FSW method, fabrication of bimetallic rods via equal channel angular pressing (extrusion) [15, 17–19], multilayered sheets by accumulative roll-bonding [20–22], and bimetallic tubes by modified high-pressure tube twisting process [23] have been investigated by researchers over the past decade. It is conjectured that the other SPD methods are also capable of producing bimetallic materials. For example, continuous high-pressure torsion [24] can be used for bimetallic wires production.
Processing of Al/Cu bimetal via a novel compound casting method
Published in Materials and Manufacturing Processes, 2019
Wenming Jiang, Feng Guan, Guangyu Li, Haixiao Jiang, Junwen Zhu, Zitian Fan
Currently, Al/Cu bimetal has an expansive application prospect in automobile, electricity as well as decoration fields[1,2], because it combines the advantages of the good electrical and thermal conductivities of the Cu with the merits of the low density, excellent castability, superior corrosion resistance as well as low cost of the Al, which can decrease about 40% weight and 60% cost and offer an equivalent conductivity in comparison with the monolithic Cu.[3,4]