Flow rate measurements in turbulent liquid metal channel flow using Time-of-Flight Lorentz force velocimetry

Non-contact flow control and flow measurements in hot and aggressive metal melts are big challenges in metallurgical applications. Time-of-Flight Lorentz force velocimetry (ToF LFV) is an electromagnetic measurement technique to meet these challenges. Our experimental results demonstrate that this method is well suited to measure flow rate in turbulent liquid metal channel flow without knowledge of both melt and magnetic field properties. Moreover, the measured flow profiles are in very good agreement with predictions of numerical simulations using the commercial program Package FLUENT MHD. (© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Electromagnetic flow rate measurement in turbulent liquid metal channel flow

Flow control in hot aggressive melts is a big challenge for metallurgical and glass technology applications. For instance, during the production of float glass, the glass melt solidifies on the top of a liquid tin bath. To achieve a spatially homogeneous glass thickness, both global and local control of the thermofluiddynamic transport phenomena in the tin bath are crucial. The concept a global flow control involves the coupling of the non-contact electromagnetic flow rate measurement technique of Lorentz force velocimetry and the non-contact flow driving technique of electromagnetic pumps based on rotating permanent magnets. The paper presents a model experiment using the low-melting test melt GaInSn as well as numerical simulations using the commercial code FLUENT/MHD. (© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

A Lorentz force flow meter for application at blast furnaces: design and calibration

A reference Lorentz force flow meter (LFF) has been developed to measure molten steel mass flow at the end of the runner of an experimental blast furnace. It works according to the principles of Lorentz force velocimetry [1] in which a static magnetic field interacts with a liquid metal stream. The magnetic field lines are generated by an arrangement of permanent magnets and penetrate the entire cross-section of the flow generating eddy currents and a total Lorentz force inside the melt. This force is proportional to the mass flow of the liquid metal and owing Newton's third law, there is a counter force of the same magnitude acting on the magnet system which is connected to a load cell. For accurate flow rate measurements, a “dry and wet calibration” of the LFF needs to be performed [2]. (© 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Mathematical analysis and optimal control of heavy metals phytoremediation techniques

In this work we optimize different issues related to phytoremediation techniques for heavy metals removal from shallow water, by means of a combination of mathematical modeling, optimal control of partial differential equations and numerical optimization. We introduce, analyze and solve a 2D mathematical system of nonlinear partial differential equations representing the concentrations of heavy metals, algae and nutrients in large waterbodies. Then, we formulate an optimal control problem related to the optimization of the phytoremediation process. In particular, we determine the minimal quantity of algae to be used in the heavy metals remediation process, and locate the optimal place for such algal mass. We also propose two different full algorithms for computing the numerical solution of the control problem and, finally, we present several numerical results for a realistic case.     

Congestion control using dynamic routing and flow control

In this paper, the congestion control in store and forward computer com-munication networks is studied, the method employed consists of a combination of a dynamic routing policy that minimizes the delay, and buffer nianagement schemes to control the flow of data. Simulation using liner programming has been carried out, under balanced and transient traffic conditions, on a simple 3–node network , the relative merits and drawbacks of each approach are discussed. Irland [2], showed that with static routing, the SQRT scheme improves the switch performance. In this paper it is shown that in the case of dynamic routing, the SQRT is an excellent solution to remedy the performance degradation caused by CP and CS schemes     

Evaluating environmental performance using statistical process control techniques

This paper builds on recent work on measuring and evaluating environmental performance of a process using statistical process control (SPC) techniques. We propose the CUSUM chart as a tool to monitor emissions data so that abnormal changes can be detected in a timely manner, and we propose using process capability indices to evaluate environmental performance in terms of the risk of non-compliance situations arising. In doing so, the paper fills an important gap in the ISO 14000 and TQEM literatures, which have focused more on environmental management systems and qualitative aspects rather than on quantitative tools. We explore how process capability indices have the potential to be useful as a risk management tool for practitioners and to help regulators execute and prioritize their enforcement efforts. Together, this should help in setting up useful guidelines for evaluating actual environmental performance against the firm's environmental objectives and targets and regulatory requirements, as well as encouraging further development and application of SPC techniques to the field of environmental quality management and data analysis.     

Time-like solutions to the Lorentz force equation in time-dependent electromagnetic and gravitational fields

We find existence and multiplicity results for time-like spatially periodic trajectories of massive particles carrying an electric charge q and subjected to time-dependent gravitational and electromagnetic fields. Such trajectories are obtained by projecting, on the base space-time, time-like geodesics with respect to a suitable Kaluza-Klein metric.     

Evaluating environmental regulation in Spain using process control and preventive techniques

Because environmental regulations may be adjusted over time to reflect updated understanding or new circumstances, there may be scope for strategic behaviour too. Regulations affect not only current emission levels, but also the effect on investment in R&D or new plant and equipment and, consequently, on competitive priorities. Although most of the literature devoted to the environmental regulation highlights the effects that legislation has on the adoption of decisions related to the environment as a competitive opportunity, there is actually no strong empirical evidence which supports that argument. This is why the present paper has as its aim to identify (1) how the regulation concerning the natural environment differs across sectors and (2) how it can influence managerial perceptions of the role to be played by the natural environment as a competitive opportunity. The research work has been carried out in two phases. The first phase involved comparative case studies of eight Spanish firms; during the second, the propositions emerging from the first phase were tested through a structural equation model of 239 hotels and 208 firms affected by the IPPC law in Spain. This paper has made a contribution to the existing research literature through the examination of the similarities and differences concerning managerial decision-making in the field of natural environment regulations. Moreover, a contact point between the Porter hypothesis and its criticism is offered. In relation to practical implications, updated information about the European, National and Community environmental legislation is presented that affects firms from eight sectors. In this context, legal environmental requirements are identified so as to make easier the adoption of managerial decisions which guarantee compliance with the law and avoidance of fines.     

Robust position/force control of multiple robots using neural networks

The control of multiple redundant robots, whose end-effectors grasp an object, involves complex control tasks. First, the multiple robotic system, for a cooperative task, forms closed kinematic chains that impose additional kinematic and dynamic constraints. Second, the interactive actions among the robots through the object lead to the essential need to control position and interactive force, simultaneously. Finally, the structured and unstructured uncertainties of the system may cause the system to be unstable. In this paper, a robust controller, which compensates the uncertainties of the dynamic system of the multiple robotic system, is presented in order to obtain good tracking performance of position and force, simultaneously, while satisfying the constraint conditions among the robots. A neural network architecture is proposed as one approach to the design and implementation of the robust controller. In particular, an on-line learning rule is provided for reportedly assigned tasks so that the system is robust to the structured/unstructured uncertainties; and the controller adjusts itself repeatedly to improve the performance progressively for each repeated task.     

Numerical solution of singular control problems using multiple shooting techniques

Algorithms for calculating the junction points between optimal nonsingular and singular subarcs of singular control problems are developed. The algorithms consist in formulating appropriate initialvalue and boundary-value problems; the boundary-value problems are solved with the method of multiple shooting. Two examples are detailed to illustrate the proposed numerical methods.The author would like to thank Professor Dr. R. Bulirsch, who stimulated and encouraged this work, which is part of the author's dissertation.     

Controlling chaos in tapping mode atomic force microscopes using improved minimum entropy control

Minimum entropy control technique, an approach for controlling chaos without using the dynamical model of the system, can be improved by being combined with a nature-based optimization technique. In this paper, an ACO-based optimization algorithm is employed to minimize the entropy function of the chaotic system. The feedback gain of a delayed feedback controller is adjusted in the ACO algorithm. The effectiveness of the idea is investigated on suppressing chaos in the tapping-mode atomic force microscope equations. Results show a good performance. The PSO-based version of the minimum entropy control technique is also used to control the chaotic behavior of the AFM, and corresponding results are compared showing almost a same functionality for the two optimization algorithms of PSO and ACO as the minimizing engines of the minimum entropy strategy.     

Active control of combustion instability using fuel flow modulation

Phase-shift control was applied to an atmospheric premix combustor test rig equipped with a swirl-stabilized burner by modulating the pilot fuel flow. The employed closed loop control circuit incorporated condenser microphones recording the pressure oscillations inside the combustion chamber and valves controlling the fuel mass flow. The microphone signals were processed and command signals were sent to the valves. The rms of the pressure oscillations was reduced by up to 12 dB, the peak amplitude by up to 20 dB. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Mathematical modelling of flow control in a tundish using electro-magnetic forces

The control of flow in a tundish is important for improving the quality of the steel. Dams, Wiers and Pouring chamber are some of the devices used for controlling the flow in the tundish. The investigation about the role of electromagnetic forces as a replacement for these devices is an objective for the present work. Thus, 3-D MHD simulation was performed to study the effect of electromagnetic forces on flow behaviour in the tundish. The MHD model developed for carrying out the simulation was validated with the analytical solution of the Hartman problem. The results obtained shows improvement in the desired characteristics for inclusion flotataion with magnetic flow modifier of optimum strength of magnetic field.     

Analytical estimation of liquid film thickness in two-phase annular flow using electrical resistance measurement

This paper presents an analytical solution to estimate the liquid film thickness in two-phase annular flow through a circular pipe using electrical resistance tomography. Gas–liquid flow with circular gas core surrounded by a liquid film is considered. Conformal mapping is employed to obtain the analytic solution for annular flow with an eccentric circular gas core. The liquid film thickness for an arbitrary annular flow is estimated by comparing the resistance values for concentric and eccentric annular flows. The film thickness estimation has a good performance when the normalized distance between the gas core center and the flow center is less than 0.2 and the void fraction is greater than 0.4, the estimated error of the normalized thickness is less than 0.04.     

One inverse problem in the theory of liquid metals

The possibility of direct determination of the Fourier component of the model potential of the electron-ion interaction, as well as the polarization and structural characteristics of a degenerate electron liquid, based on the condition of the availability of experimental information about partial structural factors, is demonstrated using the model of a one-component plasma as an initial approximation. The possibility for self-consistent calculations of the volume and surface properties of liquid metals is also shown.Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 105, No. 3, pp. 462–470, December, 1995.     

Simulation of mass transfer in liquid/liquid slug flow

The mass transport for a liquid/liquid extraction system is examined using a numerical concept following the idea of the interface-tracking method. Separate, body-fitted, static computational domains are arranged around an imported steady-state interface topology. The domains are coupled at the free interface to capture the behaviour of the conjugated system. The steady-state hydrodynamics are the basis for the simulation of the transient mass transport, which is calculated as a passive scalar concentration or one-way coupling. The investigation is restricted to the extraction from the disperse to the continuous phase. Simulation results for an extraction from the disperse to the continuous phase show that most of the mass is transferred through the wall-film region into the continuous phase. (© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Measure change techniques in optimal control

Fully and partially observed stochastic control of systems with nonlinear dynamics and terminal and running costs are considered. Measure changes are introduced which allow both state and observation dynamics to be thought of as linear. In the case when the terms of the cost have a special form the measure change transformation “cancels out” the nonlinearities and changes the original nonlinear problem into a classical LQG one and standard results can be applied. We also consider unnormalized conditional densities of the whole path as state variables and obtain dynamic programming and verification results. R. J. Elliott wishes to acknowledge support of the Natural Sciences and Engineering Research Council of Canada, Grant A7964.     

Control of hydrothermal waves in a thermocapillary flow using a gradient-based control strategy

The problem of controlling the hydrothermal waves in a thermocapillary flow is addressed using a gradient based control strategy. The control is a spatially and temporally varying heat flux boundary condition at the free surface. The control which minimizes the hydrothermal waves is found using a conjugate gradient method, where the gradient of the objective function with respect to the control variables is obtained from solving a set of adjoint equations. (© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Stabilization of the incompressible 2D Euler equations in a simply connected domain utilizing the Lorentz force

In this paper, the null asymptotic stabilization of the 2D Euler equations of incompressible fluids in a simply connected bounded domain is investigated by utilizing the Lorentz force given by the Maxwell equations with Ohm's law.