Search results for "Computer Science Applications"
showing 10 items of 3993 documents
Vibration control for adjacent structures using local state information
2014
In this paper, a novel strategy for structural vibration control of multi-structure systems is presented. This strategy pays particular attention to mitigating negative interstructure interactions. Moreover, it is based on recent advances in static output–feedback control, which make possible the efficient computation of decentralized velocity-feedback controllers by solving a single-step optimization problem with Linear Matrix Inequality constraints. To illustrate the main ideas, a local velocity-feedback energy-to-peak controller is designed for the seismic protection of a two-building system. This controller is remarkably effective and extremely simple. Moreover, it can also be implement…
Friction Stir Welding Lap Joint Resistance Optimization Through Gradient Techniques
2007
In recent years, scientific interest on friction stir welding (FSW) has grown more and more since such a joining technique allows one to weld lightweight alloys that are rather difficult to weld or even “unweldable” with the classic fusion welding operations. Furthermore, few industrial applications of the process are already known in different manufacturing fields. In this paper, the optimization problem of a FSW lap joint for automotive applications is investigated, taking into account process parameters such as the tool rotating speed and the tool feed rate; a numerical gradient technique is applied for the optimization procedure reducing the number of experimental tests to be developed.
Least squares and genetic algorithms for parameter identification of induction motors
2001
Abstract This paper deals with off-line parameter identification of induction motors by means of least square (LS) techniques and genetic algorithms (GA), using stator voltages, stator currents and velocity as input–output data. For analytical identification by LS algorithms, filtering of experimental data is performed by means of anticausal filters. Two models useful for identification are derived in which the products of acceleration and rotor fluxes, usually neglected, are taken into account. The GA-based identification method consists of the determination of the best parameters which match input–output behaviour of the motor. Both methods are investigated and compared by means of experi…
Modeling of Wind Turbine Gearbox Mounting
2011
In this paper three bushing models are evaluated to find a best practice in modeling the mounting of wind turbine gearboxes. Parameter identification on measurements has been used to determine the bushing parameters for dynamic simulation of a gearbox including main shaft. The stiffness of the main components of the gearbox has been calculated. The torsional stiffness of the main shaft, gearbox and the mounting of the gearbox are of same order of magnitude, and eigenfrequency analysis clearly reveals that the stiffness of the gearbox mounting is of importance when modeling full wind turbine drivetrains.
Innovative modeling of tuned liquid column damper controlled structures
2016
In this paper a different formulation for the response of structural systems controlled by Tuned Liquid Column Damper (TLCD) devices is developed, based on the mathematical tool of fractional calculus. Although the increasing use of these devices for structural vibration control, it has been demonstrated that existing model may lead to inaccurate prediction of liquid motion, thus reflecting in a possible imprecise description of the structural response. For this reason the recently proposed fractional formulation introduced to model liquid displacements in TLCD devices, is here extended to deal with TLCD controlled structures under base excitations. As demonstrated through an extensive expe…
Offshore Wind Payload Transfer Using Flexible Mobile Crane
2015
This article presents an offshore-simulated loading and unloading of a payload from a floating platform to a fixed structure. The experiments are performed in a dry-lab, where a Stewart platform is used to simulate the motion of the vessel. A hydraulically actuated vehicle loader crane is used to perform the tasks of payload transfer. The crane includes a hydraulic winch where the wire force is measured by a load cell. A mathematical model of the winch is derived and is experimentally verified. The control strategies include a heave compensation and a constant tension mode. A motion reference unit is used to generate the reference motion of the moving platform. Experimental results show the…
A force measuring based strategy for failure prevention in incremental forming
2006
Abstract Incremental forming processes show a number of advantages compared to the traditional processes but, at the same time, some drawbacks are clearly known. Current problems, include the slowness of the process, low accuracy and a lack of knowledge in the field of material formability. This paper is focused on the latter issue: an industrially oriented methodology for detecting the approach of failure in incremental forming is proposed. The approach is based on the analysis of the trend of the forming force in order to assess whether the process can be run safely. If not, a proper strategy, to avoid material failure, is proposed and experimentally validated.
Business models to offer customized output in electronic commerce
2003
Seller-driven business models (e.g. online bookstores) have been successfully implemented and concretized in Electronic Commerce both in practice and science in the last years. In contrast to this we can depict that more customer-driven business models are implemented in the beginning. One major problem of customizable products and services in Electronic Commerce can be found in the adaptation of the human advisory activity which is inevitable in the traditional sale. For this reason we depict the customization in the customer's view and the corresponding business models in electronic markets. Main focus will be on the improvement of the communication interface between customer and seller i…
Coordination policies to support decision making in distributed production planning
2003
Abstract Distributed production networks are considered organizational structures able to match agility and efficiency necessary to compete in the global market. Performances of such organization structures heavily depend on the ability of the network actors of coordinating their activities. The research proposes to model and design coordination problems within production network by using the Multiple Agent Technology. In particular, the paper proposes new strategies for coordinating production-planning activities within production networks. Such models have been developed and tested by using a proper simulation environment developed by using open source code and architecture. The results o…
Problems in the interplay of development and IT operations in system development projects: A Delphi study of Norwegian IT experts
2011
ContextThe assumption of the presented work is that the ability of system developers and IT operations personnel to cooperate effectively in system development projects has great impact on the quality of the final system solution, as well as on the service level of its subsequent operation. ObjectiveThe present research explores the interplay of system development and IT operations and the challenges they are meeting. We are especially interested in identifying problems encountered between these two parties in system development projects. MethodWe identify and rank problems by using a ranking-type Delphi study. We involved 42 Norwegian IT experts and split them into three expert panels: sys…