A multi-agent architecture for plug and produce on an industrial assembly platform

Modern manufacturing companies face increased pressures to adapt to shorter product life cycles and the need to reconfigure more frequently their production systems to offer new product variants. This paper proposes a new multi-agent architecture utilising “plug and produce” principles for configuration and reconfiguration of production systems with minimum human intervention. A new decision-making approach for system reconfiguration based on tasks re-allocation is presented using goal driven methods. The application of the proposed architecture is described with a number of architectural views and its deployment is illustrated using a validation scenario implemented on an industrial assembly platform. The proposed methodology provides an innovative application of a multi-agent control environment and architecture with the objective of significantly reducing the time for deployment and ramp-up of small footprint assembly systems.     

Etude des propriétés des films préparés par evaporation des solutions d'un polymére dans différents solvants

Films of a plasticized random terpolymer were prepared by evaporation of solutions in several solvents. The glass transition temperatures of the films were determined and were found to follow the Fox's equation. Their tensile modulus, measured just below the glass transition temperature, was found to depend on the residual solvent content of the films.     

Kinetics of scrap melting in liquid steel

The melting rate of steel bars with various sizes, shapes, and initial temperatures in a 70 kg liquid steel bath (1650 °C) was measured to investigate the kinetics involved in steel scrap melting. Our measurements revealed that a solidified shell was formed around the original bar immediately after it was immersed into the liquid steel. This shell and an associated interfacial gap generated between it and the original bar were found to be critical to the melting kinetics. We also found that the total melting time decreased linearly with increasing initial bar temperature. The melting process was simulated using a two-dimensional phase-field model that considered heat convection with a constant heat-transfer coefficient. Our simulations were in good agreement with our experiments and showed that the heat conduction associated with the interfacial gap was one of the most important physical aspects controlling the melting of steel scrap.     

Transport properties of porous media from the microgeometry of a three-dimensional voronoi network

In this work a way of calculating effective transport coefficients from the microgeometry of a porous medium is presented. The model material consists of a random packing of uniform spheres, and by applying the Voronoi—Delaunay tessellation technique the void between the spheres is simulated as a network of cylindrical pores. The tessellation yields all the necessary information for the structural characterization, such as the pore diameter, pore angle and pore length distribution functions and the topological interconnection. The effective transport coefficients of ordinary diffusion, Knudsen flow and viscous flow are calculated numerically by mass balancing at each network node and over all nodes of the system. The results obtained agree very well with the experimental ones, especially for ordinary diffusion. For Knudsen and viscous flow, inaccuracies in the estimation of the pore overlapping volume cause a relative error between the numerical and experimental results of the order of 16%–33%.     

Structure and development of causal€xperimental thought: From early adolescence to youth.

Investigated the structure and development of causal–experimental thought. 260 Ss (aged 12–16 yrs) were examined by 3 test batteries. The batteries involved items addressing combinatorial, hypothesis handling, experimentation, and model construction abilities. Confirmatory factor analysis indicated that these abilities, although distinct from each other, do share a common functional core, and they are organized in a higher order causal–experimental specialized structural system. Rasch scaling indicated that these 4 kinds of abilities follow overlapping developmental trajectories. Saltus modeling suggested that development is continuous rather than discontinuous. Individual differences were found in the rate of acquisition but not in the structure of abilities. A model of synergic developmental causality was proposed to account for this pattern of development. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Signaling Performance Trials and Evaluation Results on a GPRS Platform

Generic Packet Radio Service (GPRS) enhances data transfers up to occasional transmission of large amounts of user data. Signaling procedures are specified for the provision of connection oriented services and the establishment of data channels between mobile subscribers. The time-overhead introduced with the performance of end-to-end signaling operations is a crucial performance factor that determines the provided Quality of Service (QoS). A significant time-overhead associated with the high rate establishment and release of many short-lived data channels, required during hand-over or for Internet access, would result in network performance degradation.Nevertheless, despite its main significance, there is a lack of papers in the Internet community that either investigate the issue of GPRS signaling performance or present GPRS trials and measurements. This lack becomes even more obvious and gets more importance from the moment that the deployment of GPRS, at least in the first phase, revealed significant performance delays in the connection setup times.To this respect, this paper presents the experiments conducted at a GPRS testing platform focusing on the performance assessment of signaling functionality. The trials focus on the performance evaluation of the GPRS signaling operations related to the establishment and release of user data channels through the Gn and Gi interfaces. Timing results that quantify the overall delay under diverse conditions of signaling load, rate and subscribers are presented.     

Entwicklung eines Transformationsmodells – Modularisierung schrittweise gedacht

For some years now, the process industry has been meeting the challenges of the markets with modular production and logistics concepts. This article presents this development process in the form of a four-stage transformation model. It is shown that the path towards modular production environments can be taken step by step. The motto is “evolution instead of revolution”. First, an overview of the state of the art of modularized production and logistics systems is given. Based on this, the article describes and classifies the four different stages of modularization.     

Optimized capacitive active ripple compensation topology for a 3.7 kW single-phase high power density on-board charger of electric vehicles

Electrical Engineering - In this paper, a comprehensive investigation of the capacitive active ripple compensation (ARC) techniques is made to conclude which one is optimal to be used in on-board...     

Automated experience-based learning for plug and produce assembly systems

This paper presents a self-learning technique for adapting modular automated assembly systems. The technique consists of automatically analysing sensor data and acquiring experience on the changes made on an assembly system to cope with new production requirements or to recover from disruptions. Experience is generalised into operational knowledge that is used to aid engineers in future adaptations by guiding them throughout the process. At each step, applicable changes are presented and ranked based on: (1) similarity between the current context and those in the experience base; (2) estimate of the impact on system performance. The experience model and the self-learning technique reflect the modular structure of the assembly machine and are particularly suitable for plug and produce systems, which are designed to offer high levels of self-organisation and adaptability. Adaptations can be performed and evaluated at different levels: from the smallest pluggable unit to the whole assembly system. Knowledge on individual modules can be reused when modules are plugged into other systems. An experimental evaluation has been conducted on an industrial case study and the results show that, with experience-based learning, adaptations of plug and produce systems can be performed in a shorter time.     

Direct measurement of the spectral transfer function of a laser based anemometer

The effect of a continuous-wave (cw) laser based anemometer's probe volume on the measurement of wind turbulence is studied in this paper. Wind speed time series acquired by both a remote sensing cw laser anemometer, whose line-of-sight was aligned with the wind direction, and by a reference sensor (sonic anemometer) located in the same direction, were used. The spectral transfer function, which describes the attenuation of the power spectral density of the wind speed turbulence, was calculated and found to be in good agreement with the theoretical exponential function, which is based on the properties of the probe volume of a focused Gaussian laser beam. Parameters such as fluctuations of the wind direction, as well as the overestimation of the laser Doppler spectrum threshold, were found to affect the calculation of the spectral transfer function by introducing high frequency noise.