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Ocean Hydrodynamics
Published in Victor Raizer, Optical Remote Sensing of Ocean Hydrodynamics, 2019
There are several types of flow that occur in practice: uniform and non-uniform flow, steady and unsteady flow, laminar and turbulent flow. Figure 2.2 shows types of fluid flow. Uniform flow is flow with constant section area along the flow path (the velocity at given time does not change with respect to space); non-uniform flow is flow with a variable section area (the velocity at any time changes with respect to space). Steady flow is time-independent; unsteady flow is time-dependent. Laminar flow, also known as streamline flow, is smoother, and fluid particles move very orderly along parallel layers. Turbulent flow is more chaotic, motion is locally completely random, and complex flow patterns constantly change and take form of vortexes or eddies. There is a category of flow known as the transitional flow, which is a mixture of laminar and turbulent flow (this flow mostly occurs in the pipe).
Some recent developments in interactive computer graphics for 3-D nonlinear geotechnical FEM analysis
Published in G. Swoboda, Numerical Methods in Geomechanics Innsbruck 1988, 2017
Fred H. Kulhawy, Kirk L. Gunsallus, Anthony R. Ingraffea, Patrick C.-W. Wong
The engineering analysis and design process for complex problems often relies on the results of finite element analyses. However, the preparation of input data and presentation of output results can be very frustrating for the creative engineer. To avoid being overwhelmed by input and output concerns, the engineer often delegates the analysis to computer or systems people and simply responds to their presentations. Another alternative is to utilize simplified closed form solutions or estimations based on similar problems examined in the literature. In either case, the design engineer is not dealing directly with the analysis of the actual problem.
Time-dependent reliability analysis for a set of RC T-beam bridges under realistic traffic considering creep and shrinkage
Published in European Journal of Environmental and Civil Engineering, 2022
Fatima El Hajj Chehade, Rafic Younes, Hussein Mroueh, Fadi Hage Chehade
Some analytical and numerical approaches are used to estimate the lateral live load distribution on Girder Bridge. For example AASHTO and Henry’s methods give load distribution factors, but they are considered greatly simplified and are mainly intended for design purpose, they may not be indicative also in case of in-service behaviour (Harris, 2010). Nowadays, finite element methods are widely used especially with the development of finite element software that allows predicting the actual behaviour of complex structures based on a refined modelling. In this study, the lateral distribution of vehicle loads on the girders is predicted according to Guyon-Massonnet method which is an analytical method based on the orthotropic plate theory (Massonnet, 1962), (Bondonet & Corfdir, 2005). A corresponding Matlab code was developed that allows generating the profile of lateral distribution for each girder. Therefore, this code will be simply linked to the probabilistic code and permits an accurate calculation of the load effect under time-variant random traffic loading. The structural analysis is then reduced to the analysis of a beam component in longitudinal direction.
A unified ensemble of surrogates with global and local measures for global metamodelling
Published in Engineering Optimization, 2021
Jian Zhang, Xinxin Yue, Jiajia Qiu, Muyu Zhang, Xiaomei Wang
High-fidelity computer simulations such as finite element analysis play an important role in the design and optimization of complex engineering systems. Despite the rapid development of computing technology, the need to obtain more accurate and reliable simulation results with ever-increasing complexity of numerical models still makes engineering system analysis time-consuming. Hence, surrogate models (also known as metamodels) are widely used to replace computationally expensive high-fidelity simulations for efficient estimation of system characteristics. Commonly used surrogate models in engineering design and optimization include polynomial response surface (PRS) (Wang, Dong, and Aitchison 2001; Wang 2003; Myers, Montgomery, and Anderson-Cook 2016), radial basis function (RBF) (Fang and Horstemeyer 2006; Liu et al. 2006; Sun et al. 2011; Shi et al. 2016), kriging (KRG) (Martin and Simpson 2005; Regis 2016; Huang et al. 2019) and support vector regression (SVR) (Clarke, Griebsch, and Simpson 2005; Wang, Li, and Li 2010; Wang et al. 2011). More information on surrogate modelling techniques and applications can be found in the relevant references (e.g. Wang and Shan 2007; Shan and Wang 2010; Wang et al. 2017; Chen et al. 2019).
A Framework Utilizing Augmented Reality to Enhance the Teaching–Learning Experience of Linear Control Systems
Published in IETE Journal of Research, 2021
Deepti Prit Kaur, Archana Mantri, Ben Horan
Control System is defined as the interconnection of interacting components which form a system configuration to provide a desired system response. Such systems are used to achieve increased productivity and improved performance of a device or system. The basis for analysis of a control system is governed by linear system theory, which assumes the cause and effect relationship for the components of a system [31]. A control system that satisfies the requirement of linearity (if system output is linear with respect to input and follows the rule of superposition) and time invariance (if the relation between system input and output is independent of the passage of time) is termed as LTI Control System. An LTI system can be open loop or closed loop based on its classification. While an open loop system is a simple yet less accurate system, a closed loop is complex but self-correcting and more accurate control system. Despite having many advantages over open loop system, a closed loop system tends to become unstable due to the presence of feedback which was used for the purpose of reducing the error between reference input and desired output of the system.