Search results for "Variable"
showing 10 items of 1674 documents
A DC current transformer for large bandwidth and high common-mode rejection
1999
A review of known magnetic-coupled current-sensing techniques is presented, Subsequently, a novel technique is introduced, based on a configuration discussed in a previous paper. The previous technique made use of a galvanomagnetic device (Hall effect sensor) to sense the magnetization of a current transformer core, so that the sum of the Hall voltage and the voltage across the secondary shunt resistor would yield a faithful copy of the input current. The technique described in this paper makes use of the same principle to obtain a high bandwidth (from DC to 1 MHz) and very high common-mode rejection current transformer, without the need for a Hall effect probe. This is achieved by subtract…
ECONOMIC-STATISTICAL DESIGN APPROACH FOR A VSSI X-BAR CHART CONSIDERING TAGUCHI LOSS FUNCTION AND RANDOM PROCESS SHIFTS
2014
Economic design approaches of control charts are commonly based on the assumption that various cost parameters values and the occurrence risk of assignable causes have to be a priori known with precision. However, in real operative contexts, such parameters can be really difficult to accurately estimate, especially considering costs arising from out-of-control conditions of the process. As consequence, pure economic design approaches can involve chart schemes with low statistical performance. To overcome such limitation, it is herein proposed a multi-objective economic-statistical design approach for an adaptive X-bar chart. In particular, such approach aims at the minimization of both the…
Robust Predictive Control of a variable speed wind turbine using the LMI formalism
2014
This paper proposes a Robust Fuzzy Multivariable Model Predictive Controller (RFMMPC) using Linear Matrix Inequalities (LMIs) formulation. The main idea is to solve at each time instant, an LMI optimization problem that incorporates input, output and Constrained Receding Horizon Predictive Control (CRHPC) constraints, and plant uncertainties, and guarantees certain robustness properties. The RFMMPC is easily designed by solving a convex optimization problem subject to LMI conditions. Then, the derived RFMMPC applied to a variable wind turbine with blade pitch and generator torque as two control inputs. The effectiveness of the proposed design is shown by simulation results.
Robust Design of Automated Guided Vehicles System in an FMS
1996
Automated Guided Vehicles (AGV), as material handling systems, are widely diffused in FMS environment. The design of such a system involves the selection of the most suitable lay-out on one hand, and the choice of the “optimal” level of some parameters such as the number of vehicles. machine buffer capacity, the number of pallets, vehicle and part dispatching rules, etc. on the other. The optimal combination of these factor levels, that maximises a certain output variable, could be uncovered by Response Surface Methodology (RSM). But two are the problems that immediately arise in the application of such a technique: how to consider the qualitative variables, like dispatching or loading rule…
Risk Assessment of a compound feed process based on HAZOP analysis and linguistic terms
2016
[EN] The size and complexity of industrial plants, along with the characteristics of the products used, require a study, analysis and control of the existing risks in every industrial process. In this paper, a methodology for risk assessment in industrial plants, based on the combination of risks identification through the Hazard and Operability (HAZOP) analysis and the risks evaluation through linguistic variables and fuzzy numbers is applied to a case study consisting on a compound feed plant located in the town of Silla (Valencia, Spain). The results from this study show that the main risk in the compound feed production process is the formation of explosive atmospheres (ATEX). Therefore…
Feasibility issues in static output-feedback controller design with application to structural vibration control
2014
Recent results in output-feedback controller design make possible an efficient computation of static output-feedback controllers by solving a single-step LMI optimization problem. This new design strategy is based on a simple transformation of variables, and it has been applied in the field of vibration control of large structures with positive results. There are, however, some feasibility problems that can compromise the effectiveness and applicability of the new approach. In this paper, we present some relevant properties of the variable transformations that allow devising an effective procedure to deal with these feasibility issues. The proposed procedure is applied in designing a static…
Analysis, Modeling and Simulation of Complex Regional Clusters Activities, Using Arena Simulation Software
2014
Process modelling is the concise description of the total variation in one quantity, y, by partitioning it into a deterministic component given by a mathematical function of one or more other quantities, x1, x2... plus a random component that follows a particular probability distribution. The models are material or immaterial systems, which represent other systems, so that it may be possible to manipulate the built structures and their states. The main elements of a simulation are: attributes (describe and differentiate entities), variables (system characteristics), resources (whose capacity can be variable), tails (seen in case of unavailability of resources) and statistical accumulators (…
Analysis of the maximization of wind turbine energy yield using a continuously variable transmission system
2017
Abstract In this paper, an analytic study of the subject of mechanical power transmission in HAWT wind turbine has been carried out. For the most part, the study analyzes the use of continuously variable transmission (CVT) in order to allow the turbine and the electric generator to couple, allowing in turn, an unremitting transmission ratio adjustment. In low-wind sites, the design criteria suggest an oversizing of the wind turbine in order to generate adequate electrical power even at low wind speed. The proposed solution enhances the space of operating points since it allows the electric generator to release the rotational speed from the turbine one (limited due to structural integrity). …
Exploring the uncertainty in capacity estimation at roundabouts
2017
Abstract Purpose In gap-acceptance theory the critical and the follow-up headways have a significant role in determining roundabout entry capacities which in turn depend on circulating flow rates under a specified arrival headway distribution. Calculation considers single mean values of the gap-acceptance parameters, neglecting the inherent variations in these random variables and providing a single value of entry capacity. The purpose of this paper is to derive the entry capacity distribution which accounts for the variations of the contributing (random) variables and suggest how to consider this issue in the operational analysis of the roundabouts. Methods We performed a Monte Carlo simul…
Rendezvous Guidance Trajectories via Multiple-Subarc Sequential Gradient-Restoration Algorithm
2009
We consider the three-dimensional rendezvous between a target spacecraft in a circular orbit and a chaser spacecraft with an initial separation distance and an initial separation velocity. We assume that the chaser spacecraft has variable mass and that its trajectory is governed by three controls, one determining the thrust magnitude and two determining the thrust direction. We employ the Clohessy–Wiltshire equations, describing the relative motion of the chaser vis-a-vis the target, and the multiple-subarc sequential gradient-restoration algorithm to produce first optimal trajectories and then guidance trajectories for the following problems: P1—minimum time, fuel free; P2—minimum fuel, ti…