A Quasi‐Sliding Mode Observer‐based Controller for PMSM Drives

In this paper a quasi‐sliding mode control for a permanent magnet synchronous motor (PMSM) is proposed where a cascade control scheme based on a properly designed state observer provides accurate speed tracking performance. The ultimate boundedness of both the observation error and the speed tracking error is proven. The controller performance has been validated using hardware in the loop (HIL) tests on a simulator based on the model of a commercial PMSM drive. Tests show that the proposed observer‐based controller produces good speed trajectory tracking performance and it is robust in the presence of disturbances affecting the system.     

An integrated modelling framework to support manufacturing system diagnosis for continuous improvement

This paper proposes an integrated modelling framework for the analysis of manufacturing systems that can increase the capacity of modelling tools for rapidly creating a structured database with multiple detail levels and thus obtain key performance indicators (KPIs) that highlight possible areas for improvement. The method combines five important concepts: hierarchical structure, quantitative/qualitative analysis, data modelling, manufacturing database and performance indicators. It enables methods to build a full information model of the manufacturing system, from the shopfloor functional structure to the basic production activities (operations, transport, inspection, etc.). The proposed method is based on a modified IDEF model that stores all kind of quantitative and qualitative information. A computer-based support tool has been developed to connect with the IDEF model, creating automatically a relational database through a set of algorithms. This manufacturing datawarehouse is oriented towards obtaining a rapid global vision of the system through multiple indicators. The developed tool has been provided with different scorecard panels to make use of KPIs to decide the best actions for continuous improvement. To demonstrate and validate both the proposed method and the developed tools, a case study has been carried out for a complex manufacturing system.     

Marine paints: The particular case of antifouling paints

The authors present a general overview of marine paints, paying particular attention to the case of antifouling paints. After locating these paints in the anticorrosive protection systems used on the underwater parts of ships and/or other moving structures, a summary is made of the main types of antifouling products used through history up to the present time. This is complemented by a systematic assessment of the main types of living organisms that fix themselves to the underwater parts of ships. Consideration is also briefly made of the main basic mechanisms by which the different types of antifouling paints work. Finally a number of current research lines on antifouling technologies are mentioned.     

Development of stress-crystallized morphology during melt-spinning of polypropylene fibers

Melt-spinning of isotactic polypropylene was performed in an effort to assess how the flow field that exists within a filament affects final as-spun fiber morphology. It was concluded that the molten filament deforms chiefly by elongational flow, with some small amount of shearing flow bearing localized near the filament periphery. The resulting crystal texture is mostly comprised of lamellae oriented perpendicular (chain direction parallel) to the fiber axis, but a minority population of crystallites whose orientation is orthogonal (chain direction perpendicular) to the primary population is also present in these fibers. Post-drawing steps initially cause crystallites to rotate toward the axial direction, while the chains within them undergo intralamellar slip and become better oriented parallel to the fiber axis. At larger extensions, lamellar crystallites are pulled into microfibrillar units.     

A new way to conduct enzymatic synthesis in an active membrane using ionic liquids as catalyst support

Several active membranes were prepared by immobilization of Candida antarctica lipase B (CALB) onto the surface of ceramic membranes via three different ionic liquids (ILs): [bmim⁺][PF₆⁻], [emim⁺][NTf₂⁻] and [bmim⁺][NTf₂⁻] and compared to an active membrane obtained by simple enzyme adsorption. The performances of these various membranes were evaluated by studying the synthesis of butyl laurate by the acidolysis between butyl acetate and lauric acid in a hexane/water mixture (98:2, v/v). The results obtained show that all the membranes prepared with or without ILs were active and maintained their activity after several runs and during some months.     

Effect of synthesis conditions on the rheological properties of styrene butyl acrylate copolymers

The chemical and physical properties of synthetic polymers depend strongly on the polymerization process. This fact is even more determinant when dealing with copolymers. Styrene/butyl acrylate copolymers were synthesized using an emulsion copolymerization process. The amount of initiator, emulsifier, and transfer agent were varied in a systematic way in order to establish the relationship between polymerization conditions and rheological properties of the molten copolymers. Rheological and molecular weight results show that the different polymerization conditions have important effects on the properties of the final copolymers mainly through the development of different sequence distributions of the monomeric units in the copolymer chain. These results have been interpreted in terms of the kinetic mechanisms that explain the emulsion copolymerization processes. Furthermore, the rheological characterization is used as an additional tool in establishing the different structure of the resulting copolymers.     

Analysis of transfer procedures in elastoplasticity based on the error in the constitutive equations: Theory and numerical illustration

The aim of this work is to illustrate a methodology for the assessment of adaptive strategies for the solution of associative rate‐independent plasticity problems solved by employing the incremental displacement conforming finite element method. This is the first step towards a more rational definition of transfer operators in terms of the ensuing error. The motivating idea is the observation that change of data and/or finite element mesh from one time interval to the other can be both related to a discontinuity jump of the approximate solution across the time instant t_n. Thus, reliable a posteriori estimates will have to depend not only on the time step and finite element mesh size but also on the value of the jump. A new error estimate based on the error in the constitutive equations is developed which allows characterization of the discontinuity jump. Copyright © 2004 John Wiley & Sons, Ltd.     

Alternative Modeling Strategies for Characterizing Radio Performance

Historically, the application of logistic and Poisson regression has been focused in the social science and medical fields where the response variable typically has only a few possible outcomes. These techniques are not commonly applied to characterize military operations even though response variables that measure success or failure are commonly encountered in this field. This paper explores the application of ordinal logistic and Poisson regression as alternatives to ordinary least squares estimation for modeling operational performance in a military testing environment. The operational test planners chose a nested face‐centered experimental design, which was executed to collect test data. Three modeling techniques were employed in the analysis: multiple linear regression, ordinal logistic regression, and Poisson regression. The purpose of the study was to determine which regression technique best fits the test data. Cross validation and model goodness comparison were accomplished by assessing that the model fits for each model type in combination with a comparison of significant main effects and interactions. Finally, contrasts are provided relative to the ease of implementing each technique. Copyright © 2016 John Wiley & Sons, Ltd.     

Fully sensorless robust control of variable-speed wind turbines for efficiency maximization

This paper focuses on a sensorless robust power generation control strategy for a variable speed wind energy conversion system based on a permanent magnet synchronous generator. The proposed control strategy combines a robust observer of the aerodynamic torque, a simple technique for extracting rotor position using electrical signals, a robust observer of rotor speed, and a sliding mode based field oriented control strategy. The robust vanishing of the observation errors and tracking error is proved. Reported numerical simulations show that the proposed control policy is effective in terms of efficiency maximization and it is robust with respect to bounded parameter variations affecting the mechanical system.     

An observer based switching control strategy for the stabilization of uncertain multi-input–multi-output plants

The paper proposes a stabilizing dynamic output switching control policy, based on variable structure control, which extends recently published results to a wider class of systems, and further improves the controller performances in terms of transient duration. It is worthy of note that the proposed observer based variable structure controller, exploiting the features of the coupled switching control, is based on less restrictive conditions with respect to those traditionally assumed. The proposed controller has been tested by simulation on IFAC benchmark problem no. #90-09.