China 
Africa 
Explore chapters and articles related to this topic
A
Published in Philip A. Laplante, Comprehensive Dictionary of Electrical Engineering, 2018
AGI linear systems both continuous-time and discretetime state aggregation is obtained by linear transformation of the original state represented by an aggregation matrix G endowed with the following properties: G A = A G; G B = B ; C G = C ; where A, B, C are original system matrices (respectively state, input, and output ones) and A , B , C are aggregated system matrices. The aggregation is an eigenvalues-preservation approach and it provides order reduction by neglecting some of the system modes. For uncertainties, the aggregation defines some deterministic measures for a set of uncertain variables. For stochastic model of uncertainty the aggregation may be given by mean value, higher stochastic models or other statistical characteristics, while set membership uncertainties could be aggregated by their maximal or minimal values, mass center of the set or higher inertial moments. AGI See address generation interlock. metalization in spiral inductors off of the semiconducting substrate in a way that can lead to improved performance in some cases. air capacitor a fixed or variable capacitor in which air is the dielectric material between the capacitor's plates. air circuit breaker a power circuit breaker where the power contacts operate in air. Some versions employ an air blast to extend and clear the arc on contact opening, while others employ arc chutes with magnetic or thermal assists. air core transformer two or more coils placed so that they are linked by the same flux with an air core. With an air core the flux is not confined. air gap See magnetic recording air gap. a device used to mon-
Fire safety
Published in Phil Hughes, Ed Ferrett, Introduction to Health and Safety in Construction, 2015
They normally consist of a central insulated core, sandwiched between an inner and outer metal skin. There is no air gap. The external surface is then normally coated with a PVC covering to improve weather resistance or the aesthetic appeal of the panel. The central core can be made of various insulating materials, ranging from virtually non-combustible through to highly combustible. Differing fire hazards are associated with common types of insulation, when the panels are subjected to certain temperatures. Typical examples are: Mineral rock/modified phenolic will produce surface char and little smoke or gaseous combustion products, at temperatures above 230°C.Polyisocyanurate (PIR)/polyurethane (PUR) will char and will generate smoke and gaseous combustion products, at temperatures above 430°C PIR and 300°C PUR.▶ Expanded polystyrene (EPS) will melt and will generate smoke and gaseous combustion products, at temperatures above 430°C.
Multi-channel non-destructive testing of steel strip stress based on magneto-elastic effect
Published in Nondestructive Testing and Evaluation, 2023
Mingyang Yu, Bin Wang, Bo Li, Boyang Zhang, Qingdong Zhang
Figure 20 shows that when the sensor moves at a certain speed relative to the strip, the relationship between the output voltage signal and the loading force is remains linear, and the output signals at different speeds do not differ much. However, compared with the sensor at rest, the voltage signal curve during the sensor movement is still subject to a certain degree of fluctuation due to the lift-off effect [42]. The vibration of the mechanical system causes the air gap between the sensor and the steel strip to change, and the induced current inside the steel strip will also change. When the air gap is small, the increase of the air gap increases the magnetoresistance, and the intensity of the induced voltage signal is inversely proportional to the air gap. When the air gap is large, the system is affected by magnetic leakage, and the detection accuracy is greatly reduced. In actual production, the sensor is kept stationary, and the vibrations generated during the movement of the strip can be substantially eliminated by arranging the pinch rollers on the production line before and after the stress test, thus reducing the impact of strip runout on the test accuracy during the test [43]. If the induced signal is too weak to obtain, the excitation voltage should be increased, while the frequency and air gap would have to be reduced to improve the signal strength.
Investigation of sinusoidal shaped rotor to reduce torque ripple in axial flux permanent magnet machine
Published in International Journal of Ambient Energy, 2022
Muhadus Nazir, Junaid Ikram, Muhammad Yousuf, Syed Sabir Hussain Bukhari, Madad Ali Shah, Ali Asghar Memon, Jong-Suk Ro
2D comparison of conventional, arced, and sinusoidal trapezoidal shape magnets are done to clarify the difference between three shapes of the magnet, their effect on air gap flux density, and the magnitude of cogging torque. In Figure 3(a) conventional trapezoidal magnet, the length of the air gap is constant resulting in the constant airgap flux density. The air gap is the smallest in this case and the air gap flux density is maximum. In Figure 3(b) arced trapezoidal shape magnet has varying air gap due to which the length of the effective air gap increased. The air gap on the side edges of the magnet is maximum and in the middle of the magnet, it is minimum. The overall effective gap increases and reduces the air gap flux density. From 3(c), airgap in the sinusoidal trapezoidal shape magnet is peakier as compared to both conventional and arced trapezoidal shape magnet. Due to this the effective airgap is maximum in this case.
Development of heat and moisture transfer model for predicting skin burn of firefighter in fire environments
Published in The Journal of The Textile Institute, 2022
Yun Su, Miao Tian, Jun Li, Xianghui Zhang
The importance of the air gap between the fabric and the skin surface on the thermal protective performance of the clothing system was proved by a large number of experimental (Li et al., 2013; Wang et al., 2012) and numerical studies (Ghazy & Bergstrom, 2012, 2013) under flames or radiant heat exposures. It is assumed that the air gap can absorb thermal radiation, but ignores the impacts of emitting and scattering of thermal radiation (Ghazy & Bergstrom, 2012, 2013). The conduction and radiation heat transfer within the air gap are coupled in the air gap. The governing equation is written as (Su et al., 2016): where ρair, (cp)air and kair are the density, specific heat, and thermal conductivity of air, respectively, and qrad, air is the absorbed portion of the radiant heat flux from the thermal barrier to the skin surface. κair is the radiative absorptivity in the air gap, which is determined by the radiative properties of air and water vapor (Fu et al., 2015). The calculative equations are written as (Prasad et al., 2002): where αair is the absorptivity of air, Lair is the air gap thickness, ρg, ρa and ρv are the concentrations of the total gas, the air and the water vapor, respectively, and κa and κv are the absorptivity coefficients of the dry air and the water vapor.