Automatic Color Inspection for Colored Wires in Electric Cables

In this paper, an automatic optical inspection system for checking the sequence of colored wires in electric cable is presented. The system is able to inspect cables with flat connectors differing in the type and number of wires. This variability is managed in an automatic way by means of a self-learning subsystem and does not require manual input from the operator or loading new data to the machine. The system is coupled to a connector crimping machine and once the model of a correct cable is learned, it can automatically inspect each cable assembled by the machine. The main contributions of this paper are: (i) the self-learning system; (ii) a robust segmentation algorithm for extracting wires from images even if they are strongly bent and partially overlapped; (iii) a color recognition algorithm able to cope with highlights and different finishing of the wire insulation. We report the system evaluation over a period of several months during the actual production of large batches of different cables; tests demonstrated a high level of accuracy and the absence of false negatives, which is a key point in order to guarantee defect-free productions

Collapse of a semiflexible polymer in poor solvent

We investigate the dynamics and the pathways of the collapse of a single, semiflexible polymer in a poor solvent via 3-D Brownian Dynamics simulations. Earlier work indicates that the condensation of semiflexible polymers generically proceeds via a cascade through metastable racquet-shaped, long-lived intermediates towards the stable torus state. We investigate the rate of decay of uncollapsed states, analyze the preferential pathways of condensation, and describe likelihood and lifespan of the different metastable states. The simulation are performed with a bead-stiff spring model with excluded volume interaction and exponentially decaying attractive potential. The semiflexible chain collapse is studied as functions of the three relevant length scales of the phenomenon, i.e., the total chain length $L$, the persistence length $L_p$ and the condensation length $L_0 = \sqrt{k_B T L_p/u_0}$, where $u_0$ is a measure of the attractive potential per unit length. Two dimensionless ratios, $L/L_p$ and $L_0/L_p$, suffice to describe the decay rate of uncollapsed states, which appears to scale as $(L/L_p)^{1/3} (L_0/L_p)$. The condensation sequence is described in terms of the time series of the well separated energy levels associated with each metastable collapsed state. The collapsed states are described quantitatively through the spatial correlation of tangent vectors along the chain. We also compare the results obtained with a locally inextensible bead-rod chain and with a phantom bead-spring model. Finally, we show preliminary results on the effects of steady shear flow on the kinetics of collapse.Comment: 9 pages, 8 figure

Using an Architecture Description Language to Model a Large- Scale Information System – An Industrial Experience Report

An organisation that had developed a large Information System wanted to embark on a programme of significant evolution for the system. As a precursor to this, it was decided to create a comprehensive architectural description. T his undertaking faced a number of challenges, including a low general awareness of software modelling and software architecture practices . The approach taken for this project included the definition of a simple, specific, architecture description language. This paper describes the experiences of the project and the ADL created as part of it

Experimental assessment of ferritic stainless steel composite slabs

This paper describes investigations into the structural behaviour of ferritic stainless steel floor decking in composite construction. Although commonly used in the automotive and industrial sectors, structural applications of ferritic stainless steels are rare owing to a relative lack of knowledge, performance data and design guidance. These materials display considerably better atmospheric corrosion resistance than carbon steels, as well as having good ductility, formability and excellent impact resistance. As part of a wider investigation into the use of ferritic stainless steels in structural applications, an experimental study has been undertaken to assess the viability of using these materials for the profiled decking in composite floors. The shear connection behaviour between the steel beams and the composite slab is clearly critical and this is influenced by the through-deck welding process of the shear connectors. The practicality of this welding technique is assessed and described in this paper. Furthermore, the results of a series of push tests are presented. These enable the resistance of the shear connectors to be established and compared with the strengths specified in EN 1994-1-1 for composite slabs using galvanized steel decking

Transient thermal modelling of substation connectors by means of dimensionality reduction

This paper proposes a simple, fast and accurate simulation approach based on one-dimensional reduction and the application of the finite difference method (FDM) to determine the temperatures rise in substation connectors. The method discretizes the studied three-dimensional geometry in a finite number of one-dimensional elements or regions in which the energy rate balance is calculated. Although a one-dimensional reduction is applied, to ensure the accuracy of the proposed transient method, it takes into account the three-dimensional geometry of the analyzed system to determine for all analyzed elements and at each time step different parameters such as the incremental resistance of each element or the convective coefficient. The proposed approach allows fulfilling both accuracy and low computational burden criteria, providing similar accuracy than the three-dimensional finite element method but with much lower computational requirements. Experimental results conducted in a high-current laboratory validate the accuracy and effectiveness of the proposed method and its usefulness to design substation connectors and other power devices and components with an optimal thermal behavior.Postprint (published version

Reduced scale feasibility of temperature rise tests in substation connectors

Due to the important increase of the power of electrical transmission and distribution grids expected for the following years, especially in developing countries such as Kenya, Brazil, Philippines or Mexico among others, that have planes of generating energy from clean sources far away from the centres of consumption [1] it becomes a matter of special importance adapting and developing new substation connectors’ testing methods according to the power and temperature regimes at which they are expected to work. The international normative frame of substation connectors established both by the International Electrotechnical Committee (IEC) [2] and the National Electrical Manufacturers Association (NEMA) [3] sets standardized tests for the evaluation of high voltage connectors. These tests are routinely done within the quality plans of the manufacturers. At the moment, testing of substation connectors –and in general switchgear and fittings- is time demanding and costly due to the energy consumed by such tests. The expectations for the following years are that the power consumption of these tests will not do nothing but grow due to expected increase of power of worldwide overhead lines. For instance, today temperature rise tests in substation connectors involve power ranges up to 100 kVA, which are applied in cycles that can last several weeks. These tests are only feasible in few laboratories and at a very high cost: temporary, monetary, energetic and environmental. For this reason, following the line of other technologies such as aeronautics, naval engineering, or automotive as well as other studies done in the field of electrical engineering specially related to the corona effect [4], this study proposes to develop a reduced scale test system to perform temperature rise tests for substation connectors. Both, a theoretical framework based on analytical formulas, finite element method (FEM) simulations and experimental data has been developed to conduct reduced scale temperature rise tests and to set the conditions at which they provide comparable results to those attained in the original scale tests. Firstly, two circular loops (original and reduced scale loops) composed of a power conductor and two terminal connectors were analysed. The aim of this first study was to determine in an easy and trustful way the voltage and current values to be applied in experimental reduced scale tests to achieve the same steady-state temperature as in the original scale temperature rise test. The scale relationship between tests was set in 1:1.8, although the method proposed in this study can deal with any other scale factor. This study was useful in order to have a first sight of the final results of the procedure using substation connectors.Postprint (published version

Smart Solutions: Smart Grid Demokit

Treball desenvolupat dins el marc del programa 'European Project Semester'.The purpose of this report is to justify the design choices of the smart grid demo kit. Something had to be designed to make a smart grid clear for people who have little knowledge about smart grids. The product had to be appealing and clear for people to understand. And eventually should be usable, for example, on an information market. The first part of the research consisted of looking how to shape the whole system. How the 'tiles' had to look to be interactive for users and what they should feature. One part of this was doing research to get to know more about the already existing knowledge amount users. Another research investigated what appeals the most to the users. After this, a concept was created in compliance with the group and the client. The concept consists of hexagonal tiles, each with a different function: houses, solar panels, wind turbines, factories and energy storages. These tiles are all different parts of a smart grid. When combining these tiles, it can be made clear to users how smart grids work. The tiles are fabricated using a combination of 3D printing and laser cutting. The tiles have laser cut symbols on top of them to show what part of the smart grid they are. Digital LED strips are on top of the tiles to show the direction of the energy flow, and the colors indicate if the tile is producing or consuming power from the grid. The tiles are connected to each other by the so called “grid blocks”. These blocks make up the central power grid and are also lighting up by LED strips. Each tile is equipped with a microcontroller which controls the LED strips and makes it possible for the different tiles to “talk” with each other. Using this, the central tile knows which tiles are connected to the system. The central tile controls all tiles and runs the simulation of the smart grid. For further development of the project, it can be investigated how to control and adjust the system from an external system, for example by a tablet. The final product consists of five tiles connected by seven grid blocks which show how a smart grid works

Analysis of Shear Lag in Steel Angle Connectors

Previous research has found an empirically based method for calculating the effective net area defined by stress distributions created by tensile loads in steel connections. Based on the results from that method a theoretical alternative is explored to simplify the process of determining the effective net area