Shape Control

The most stable formula for a rational interpolant for use on a finite interval is the barycentric form [1, 2]. A simple choice of the barycentric weights ensures the absence of (unwanted) poles on the real line [3]. In [4] we indicate that a more refined choice of the weights in barycentric rational interpolation can guarantee comonotonicity and coconvexity of the rational interpolant in addition to a polefree region of interest.In this presentation we generalize the above to the multivariate case. We use a product-like form of univariate barycentric rational interpolants and indicate how the location of the poles and the shape of the function can be controlled. This functionality is of importance in the construction of mathematical models that need to express a certain trend, such as in probability distributions, economics, population dynamics, tumor growth models etc.

This paper presents an analysis of sub-2.5-V topologies and design methodologies for SiGe BiCMOS and sub-90nm CMOS building blocks to be used in the next generation of 40-100 Gb/s wireline transceivers. Examples of optimal designs for 40-80Gb/s broadband low-noise input comparators, low-voltage high-speed MOS- and BiCMOS CML logic gates, 30-100 GHz low-noise oscillators, and 40/80 GHz output drivers with wave shape control are provided.

Nanostructured Fe3O4 nanoparticles were prepared by a simple sonication assisted co-precipitation method. Transmission electron microscopy, X-ray diffraction and BET surface area analysis confirmed the formation of ∼20 nm crystallites that constitute ∼200 nm nanoclusters. Galvanostatic charge–discharge cycling of the Fe3O4 nanoaprticles in half cell configuration with Li at 100 mA g−1 current density exhibited specific reversible capacity of 1000 mAh g−1. The cells showed stability at high current charge–discharge rates of 4000 mA g−1 and very good capacity retention up to 200 cycles. After multiple high current cycling regimes, the cell always recovered to full reversible capacity of ∼1000 mAh g−1 at 0.1 C rate.• A simple and inexpensive ultrasonic assisted co-precipitation route has been followed to make monodisperse Fe3O4 nanoparticles. • Anodes made from the Fe3O4 nanoparticles exhibit specific reversible capacity of ∼1000 mAh g−1. • The anodes could operate at a current density from 100 to 4000 mA gm−1 with coulombic efficiency of almost 100%. • The anodes showed excellent cyclic stability for at least 200 cycles without capacity fade, and returned to specific capacity of 1000 mAh gm−1 at 0.1 C after multiple high current charge–discharge cycles.

This paper presents a reliable method for constructing a control mesh whose Doo-Sabin subdivision surface interpolates the vertices of a given mesh with arbitrary topology. The method improves on existing techniques in two respects: (1) it is guaranteed to always work for meshes of arbitrary topological type; (2) there is no need to solve a system of linear equations to obtain the control points. Extensions to include normal vector interpolation and/or shape adjustment are also discussed.

A new control scheme for induction motors is proposed in the present paper, applying the interconnection and damping assignment-passivity based control (IDA-PBC) method. The scheme is based exclusively on passivity based control, without restricting the input frequency as it is done in field oriented control (FOC). A port-controlled Hamiltonian (PCH) model of the induction motor is deduced to make the interconnection and damping of energy explicit on the scheme. The proposed controller is validated under computational simulations and experimental tests using an inverter prototype.

The thermo-mechanical analysis of a simply supported, functionally graded shell is considered in this work. Refined shell theories are considered to account for grading material variation in the thickness direction. The governing thermodynamical equations are derived from the Principle of Virtual Displacements. The distribution of the temperature field T(z) is not assumed linear in the thickness direction of the layered shells and Fourier's heat conduction equation is solved to provide T(z). Classical and higher order shell theories are implemented in cases of both an equivalent single layer and layer-wise variable description by referring to Carrera's Unified Formulation. The numerical results show temperature, displacement and stress distributions along the thickness direction. Different volume fractions of the metallic and ceramic constituents as well as different shell thickness ratios and orders of expansion are analyzed. These are in good agreement with the quasi-3D solution obtained considering mathematical layers with constant properties in the FGM layer and using high orders of expansion.

An attempt has been made to develop Virtual Training Platform for Pickling Line Tandem Cold Mill (PLTCM) intended to deliver faster and enhanced learning experience of the process operator by leveraging Advanced Data Modelling, Data Science and Digital Twin Technology. Virtual Training Platform has modules for virtual tour of the plant, setup simulation, real-time rolling simulation, performance evaluation. Rolling Simulation has ANN based Automatic gauge control model and DNN based shape prediction model. Platform also comprises of a Natural Language Processing based chatbot for online query related to process line.

Computational complexity is a prohibitive factor in evolutionary optimization of sufficiently large and/or complex problems. Much of this computational complexity is due to the fitness function evaluation that may either not exist or be computationally very expensive. Here, we investigate the use of fitness granulation via an adaptive fuzzy similarity analysis as applied to two different hardware design problems that are evaluated using finite element analysis. The first design problem is a relatively simpler 2-D truss frame design with 36 parameters while the second problem is piezoelectric voltage and pattern arrangement design for static shape control in which 200 parameters are optimized. In comparison with standard application of evolutionary algorithms, statistical analysis reveals that the proposed method significantly decreases the number of fitness function evaluations while finding equally good or better solutions. Additionally, this more improvement is indicated with higher problem complexity.

We present a rotating-tip-based mechanical nanomanufacturing technique, referred to here as nanomilling. An atomic force microscopy (AFM) probe tip that is rotated at high speeds by out-of-phase motions of the axes of a three-axis piezoelectric actuator is used as the nanotool. By circumventing the high-compliance AFM beam and directly attaching the tip onto the piezoelectric actuator, a high-stiffness arrangement is realized. The feeding motions and depth prescription are provided by a nano-positioning stage. It is shown that nanomilling is capable of removing the material in the form of long curled chips, indicating shearing as the dominant material removal mechanism. Feature-size and shape control capabilities of the method are demonstrated.

This article addresses a robust controller design technique for an uncertain linear time invariant plant with input saturation constraint. The uncertainty of the plant is presented in a normalised coprime factorisation framework, which is a general description of the unstructured uncertainty of the system. For controller synthesis, the H ∞ loop-shaping method adopted is new to the actuator saturation control problem. In the presence of input saturation, the H ∞ loop-shaping framework has been transformed into an equivalent Lur'e-type system, and then Popov absolute stability criteria are applied to ensure closed-loop stability against unstructured uncertainty and saturation nonlinearity of the system. For the synthesising controller, a sequence of design steps has been addressed by formulating the design constraints in a bilinear matrix inequality framework. To show the effectiveness of the proposed method, a numerical example has been demonstrated.