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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
We must include several other constituents, besides the field equations, to make the postulate complete. To form a complete field theory we need a source field, a mediating field, and a set of field differential equations. This allows us to mathematically describe the relationship between effect (the mediating field) and cause (the source field). In a well-posed postulate we must also include a set of constitutive relationships and a specification of some field relationship over a bounding surface and at an initial time. If the electromagnetic field is to have physical meaning, we must link it to some observable quantity such as force. Finally, to allow the solution of problems involving mathematical discontinuities we must specify certain boundary, or “jump,” conditions.
Concurrent multiscale topology optimisation towards design and additive manufacturing of bio-mimicking porous structures
Published in Virtual and Physical Prototyping, 2023
Tian Lan, Truong Do, Oraib Al-Ketan, Kate Fox, Phuong Tran
The density field is essential in the numerical-based evaluation of the design. For the geometric component-based approach, the focus is on the bridge between the geometric design variables and the density of each element in the discretised design space. Figure 3 shows the projection mechanism to generate the density field. The projection is applied to each component before further process. As Figure 3(a) shows, the design space has been discretised into fixed eight-node cubic elements. The minimum distances between the boundary of geometric components and each element are utilised as inputs to further generate the density field via the projection function shown in Figure 3(d). In the proposed method, the inverse density fields of the core region of the bar, the shell region of the bar, and the sphere components are obtained separately at first. As Figure 3(e) shows, the inverse density fields that belong to different regions are then processed to obtain the complete field of the component. The inverse density fields for each component are assembled with further Boolean operations to obtain the inverse density field of the designed structure.
Artificial Neural Network (ANN) based Soil Temperature model of Highly Plastic Clay
Published in Geomechanics and Geoengineering, 2022
Mohammad Sadik Khan, John Ivoke, Masoud Nobahar, Farshad Amini
A complete field investigation was conducted at the monitoring area of the slope in addition to the instrumentation of the slope. Individually, at the crest, middle, and toe of each slope, three boreholes were drilled at 30 ft (9.1 m), 25 ft (7.6 m), and 20 ft (6 m) depth, respectively. The shallow to deep principal strata were the formation of weathered (the light orange to yellow clay) and unweathered (light blue to grey-blue) Yazoo clay soil (high plasticity clay). The grain size distribution, plasticity index, and liquid limit (laboratory physical properties) of the slope at different depths were determined from the soil samples collected at the sites (Table 2). The particle size distribution indicated that the samples have over 80% clay content. The soil samples were determined as high-plastic clay (CH), based on the Atterberg limits and graduation, concerning the Unified Soil Classification System (USCS). The local Yazoo clay soil has a specific gravity ranging between 2.68 and 2.72.
Non-contact temperature measurement at the Physikalisch-Technische Bundesanstalt (PTB)
Published in Quantitative InfraRed Thermography Journal, 2021
I. Müller, A. Adibekyan, K. Anhalt, C. Baltruschat, B. Gutschwager, S. König, E. Kononogova, C. Monte, M. Reiniger, S. Schiller, D. R. Taubert, D. Urban, J. Hollandt
On the one hand, the measuring set-up thus enables us to calibrate the thermographic cameras directly at the heat-pipe cavity radiators and surface radiators of PTB. On the other hand, we are able to calibrate surface radiators for customers in comparison with the heat-pipe cavity radiators by using the transfer radiation thermometers as comparison instruments. Every thermographic camera shows a pixel-to-pixel variation in its spectral response to infrared radiation. In general, this camera-specific nonuniformity is individually corrected for every camera by the manufacturer as part of the initial adjustment and calibration process. Usually, a surface radiator with a sufficiently large area to fill the complete field of view of the camera is used for this nonuniformity-correction (NUC) procedure. However, the NUC of the response of a camera cannot be better than the temperature homogeneity of the surface radiator used. In order to improve this limiting factor, PTB has developed a method for determining and correcting the nonuniformity of cameras which does not need a homogeneous radiation source.