Optimum design of large steel skeletal structures using chaotic firefly optimization algorithm based on the Gaussian map

Structural and Multidisciplinary Optimization - In this paper, a new chaotic firefly algorithm based on Gaussian map (CGFA) is proposed for structural optimization problems. Different chaotic maps...     

The UCR Time Series Archive

The UCR time series archive – introduced in 2002, has become an important resource in the time series data mining community, with at least one thousand published papers making use of at least one data set from the archive. The original incarnation of the archive had sixteen data sets but since that time, it has gone through periodic expansions. The last expansion took place in the summer of 2015 when the archive grew from 45 to 85 data sets. This paper introduces and will focus on the new data expansion from 85 to 128 data sets. Beyond expanding this valuable resource, this paper offers pragmatic advice to anyone who may wish to evaluate a new algorithm on the archive. Finally, this paper makes a novel and yet actionable claim: of the hundreds of papers that show an improvement over the standard baseline (1-nearest neighbor classification), a fraction might be mis-attributing the reasons for their improvement. Moreover, the improvements claimed by these papers might have been achievable with a much simpler modification, requiring just a few lines of code.      

Data workflow to incorporate thermodynamic energies from Calphad databases into grand-potential-based phase-field models

Journal of Materials Science - In order to approximate Gibbs energy functions, a semi-automated framework is introduced for binary and ternary material systems, using Calphad databases. To generate...     

Comparative Behavioral Modeling of POA and TOA Ranging for Location-Awareness Using RFID

How to position a tag is an important and sometimes necessary task for many RFID applications. Traditionally, there are methods using RSS and Phase to ranging a tag in literatures. But in this paper we introduce the principles of multi-tones phase of arrival (POA) based ranging in detail, and firstly compare POA and time of arrival (TOA) based ranging behavior for RFID application in a certain scenario. We characterize the RFID ranging behaviors from the view of Cramer–Rao lower bound (CRLB), Ray Tracing and empirical measurements. First, we introduce the principles of multi-tone POA ranging method, and present the details of POA based ranging CRLBs for different tones and compare it with TOA ranging. Second, we use Ray Tracing method to model the distance and bandwidth influence on POA and TOA based RFID ranging in multipath environments. Third, we establish measurement in a room to validate the noise and multipath influence on POA and TOA based RFID ranging. The ray tracing simulation and empirical experiment results show that in short range application such as RFID, POA based ranging has a comparatively better performance than TOA.     

Structural optimization by gradient‐based neural networks

In this paper a neurocomputing strategy is presented which combines data processing capabilities of neural networks and numerical structural optimization. In this strategy, an improved counterpropagation neural network is used. Two artificial neural networks are trained, one for the constraints and the other for the gradients of the constraints and structural optimization is accomplished by using these nets. All required parameters such as weight matrices in the neural networks or the gradient computations are automated in this neuro‐optimizer strategy. Numerical examples are included to demonstrate the accuracy of the results. Copyright © 1999 John Wiley & Sons, Ltd.     

Microstructural characteristics of tungsten-base nanocomposites produced from micropowders by high-pressure torsion

Micropowder mixtures of W–50% Al, W–50% Ti and W–50% Ni were subjected to severe plastic deformation at 573 K using high-pressure torsion (HPT). The powder mixtures were consolidated and nanocomposites of W/Ti, W/Ti and W/Ni, with average grain sizes as small as ～9, ～15 and ～12 nm, respectively, were formed by imposing large shear strains. The nanocomposites exhibited Vickers microhardness as high as ～900 Hv, a level that has rarely been reported for metal–matrix composites. X-ray diffraction analyses together with high-resolution transmission electron microscopy showed that in addition to grain refinement, an increase in the fraction of grain boundaries up to 20%, the dissolution of elements in each other up to ～15 mol.%, an increase in the lattice strain up to 0.6%, and an increase in density of edge dislocations up to 10¹⁶ m^?2 occurred by HPT. The current study introduces the HPT process as an effective route for the production of ultrahigh-strength W-base nanocomposites, fabrication of which is not generally easy when processing at high temperatures because of interfacial reaction and formation of brittle intermetallics.     

Simplified Numerical and Analytical Approach for Solutes in Turbulent Flow Reacting with Smooth Pipe Walls

A large group of reactions that affect water quality in distribution networks occur on the pipe wall surface. Existing simulation models are usually based on cross-sectionally averaged variables that use mass-transfer coefficients derived for constant-concentration (Dirichlet) boundary conditions to account for cross-sectional variations. In the case of a first-order wall-demand problem, the boundary condition is however of Robin type. We derive a simple one-dimensional (1D) model for the radial concentration profile of a solute of arbitrary Schmidt number (Sc) reacting with pipe walls in a fully developed turbulent flow. A modified van Driest mixing length model was used to approximate the Reynolds-averaged velocity and eddy diffusivity. Numerical solutions of the 1D model agree well with a two-dimensional mass transport model and experimental data. An asymptotic solution for high Sc is derived, which is in excellent agreement with the 1D model for Sc>100. A comparison with the mass-transfer coefficients for constant-concentration boundary conditions shows that the differences between the two boundary conditions are small.     

A new four-node quadrilateral plate bending element for highly sparse and banded flexibility matrices

In this paper, an efficient method is developed for the formation of null bases of four-node quadrilateral plate bending finite element models, corresponding to highly sparse and banded flexibility matrices. This is achieved by introducing a new four-node quadrilateral plate bending element, and using special graphs associated with the finite element models. The results are compared to those of the previously developed graph theoretical and algebraic force methods, and also the displacement approach.     

Success criteria analysis in support of probabilistic risk assessment for nuclear power plants: application on SGTR accident

Success criteria analysis (SCA) bridges the gap between deterministic and probabilistic approaches for risk assessment of complex systems.To develop a risk model,SCA evaluates systems behaviour in response to postulated accidents using deterministic approach to provide required information for the probabilistic model.A systematic framework is proposed in this article for extracting the front line systems success criteria.In this regard,available approaches are critically reviewed and technical challenges are discussed.Application of the proposed methodology is demonstrated on a typical Westinghouse-type nuclear power plant.Steam generator tube rupture is selected as the postulated accident.The methodology is comprehensive and general;therefore,it can be implemented on the other types of plants and complex systems.