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Euskarazko komunikabideak euskal Pirinioetan
Get PDFEuskarazko komunikabideen mapan pisu handiena duten eskualdeak Gipuzkoa eta Bizkaia badira ere, ezin dira gutxietsi Lapurdo, Nafarroa Beherea, Zuberoa eta Nafarroa Garaiaren iparraldeko komunikabideak ere. Alabaina, kontuan harti behar da eskualde bakoitzeko demografiaren pisua
Labor Induction failure prediction based on B-Mode Ultrasound Image Processing using Multiscale Local Binary Patterns
Get PDFLabor induction is defined as the artificial onset of labor for the purpose of vaginal birth. Cesarean section is one of the potential risks of labor induction as it occurs in about 20% of the inductions. A ripe cervix (soft and distensible) is needed for a successful labor. Changes occurring during the ripening process, will affect the interaction between cervical tissues and sound waves during ultrasound transvaginal scanning and will be perceived as gray level intensity variations in the echography image. Thus, a non-invasive method using image processing of ultrasound images may help in predicting the outcome of labor induction
Thermodiffusion Coefficients of Water/Ethanol Mixtures for Low Water Mass Fractions
Get PDFThe difficulty of measuring the thermodiffusion coefficients by optical properties of water-ethanol binary mixtures of approximately 20 wt % of water has been highlighted by several authors in recent years. This is because the concentration derivative of the refractive index (∂ n/∂ c) p,T is near zero at this concentration. For this reason, we measured the thermodiffusion coefficients by means of density analysis using the thermogravitational column technique from 5 wt % to 50 wt % at 25∘C. In addition, we measured the thermophysical properties such as density, dynamic viscosity, thermal expansion and mass expansion
DC-link Voltage Balancing Strategy based on SVM and Reactive Power Exchange for a 5L-MPC Back-to-Back Converter for Medium Voltage Drives
Get PDFThe reduced capability of multilevel converters with more than one intermediate node to balance the dc-link capacitors voltage, as well as the lack of standard modulation methods to improve their balancing performance, makes these converter topologies unattractive for real power applications. This is especially true when the load demands active power. One of these topologies is the five-level multipoint clamped (5L-MPC) converter. The back-to-back (B2B) configuration of two 5L-MPC converters and the use of a space vector modulation (SVM) that exploits the voltage balancing capability of the redundant switching vectors extend the operation conditions range in which a proper voltage balance can be achieved. However, if practical modulation restrictions are considered (limitation of voltage steps, dead times, switching losses, etc.), the voltage balance cannot be achieved for all operation conditions. In this paper, an SVM which takes into account practical restrictions is proposed. In order to guarantee the voltage balance at any operation condition, the grid-side rectifier exchanges reactive power with the grid-side LCL filter. Thus, the voltage balance of the dc-link is guaranteed while a unity grid-side power factor is achieved. The proposed modulation scheme and the voltage balancing strategy are experimentally validated in a 6.6 kV 1.5 MW 5L-MPC B2B converter
The transformation of society at the centre of a co-operative university’s mission
Get PDFMondragon Unibertsitatea (MU) is a young university created in 1997 whose roots date back to 1943. MU is a non-profit worker-owned co-operative university, of public interest, and a member of MONDRAGON Corporation, with a socially-orientated approach and calling. From the very beginning, MU’s overriding goal has been to play a part in the transformation of society through training of young students and professionals, the generation of knowledge and its subsequent transfer to the business community. Its legal-corporate status as a co-operative and its associated values are the source of its commitment to serve society, shunning any elitist considerations. Furthermore, its decision-making and management bodies include staff, students and businesses and institutions, with equal weightings and elected democratically. In the middle of an increasing public-private debate, the co-operative university claims its public service which puts the focus on its principal values of democracy, transparency, sustainability and solidarity
Evaluating embedded relational databases for large model persistence and query
Get PDFLarge models are increasingly used in Model Driven Development. Different studies have proved that XMI (default persistence in Eclipse Modelling Framework) has some limitations when operating with large models. To overcome them, recent approaches have used databases for the persistence of models. EDBM (Embedded DataBase for Models) is an approach for persisting models in an embedded relational database, providing scalable querying mechanism by runtime translation of modellevel queries to SQL. In this paper, we present an evaluation of EDBM in terms of scalability with existing approaches. GraBaTs 2009 case study (models from 8.8MB to 646MB) is used for evaluation. EDBM is 70% faster than the compared approaches to persist XMI GraBats models into databases and executes the GraBats query faster, as well as having a low memory usage. These results indicate that an embedded relational database, combined with an scalable query mechanism provides a promising alternative for persisting and querying large models
Optimising Maintenance: What are the expectations for Cyber Physical Systems
Get PDFThe need for maintenance is based on the wear of components of machinery. If this need can be defined reliably beforehand so that no unpredicted failures take place then the maintenance actions can be carried out economically with minimum disturbance to production. There are two basic challenges in solving the above. First understanding the development of wear and failures, and second managing the measurement and diagnosis of such parameters that can reveal the development of wear. In principle the development of wear and failures can be predicted through monitoring time, load or wear as such. Monitoring time is not very efficient, as there are only limited numbers of components that suffer from aging which as such is result of chemical wear i.e. changes in the material. In most cases the loading of components influences their wear. In principle the loading can be stable or varying in nature. Of these two cases the varying load case is much more challenging than the stable one. The monitoring of wear can be done either directly e.g. optical methods or indirectly e.g. vibration. Monitoring actual wear is naturally the most reliable approach, but it often means that additional investments are needed. The paper discusses the above issues and what are the requirements that follow from these for optimising maintenance based of the use of Cyber Physical Systems
Heat transferred to the workpiece based on temperature measurements by IR technique in dry and lubricated drilling of Inconel 718
Get PDFIn manufacturing aeronautical critical components, such as turbine discs commonly made of Inconel 718, surface integrity is crucial to ensure their fatigue life. Among the machining processes used, the drilling operation is one of the most critical as overheating can occur causing thermal damage to the hole. The amount of heat dissipated could determine the nature of deformation in the machining of Inconel 718. Nevertheless no detailed studies have determined experimentally the differences between the fractions of heat transferred to the workpiece (β) for dry and lubricated drilling. In this context, the thermal and mechanical loads (measured by IR technique and a piezoelectric dynamometer) affecting the drilling of Inconel 718 have been studied. Four different cutting conditions both in dry and lubricated conditions were tested. In order to obtain β, the study presents a model based on a new experimental method. The maximum β values were achieved in the unlubricated tests (around 0.20). By contrast, in the lubricated tests β range from 0.065 to 0.078. Therefore the fraction of heat conducted to the workpiece show maximum differences of 72% and minimum of 57% depending on the application or not application of coolant. Additionally, the obtained trends of β relative to Peclet number (that is dependent on the cutting speed, feed and drill diameter) are shown
Robustness of inventory replenishment policies and client selection methods for the stochastic and dynamic inventory-routing problem
Get PDFWhen inventory management, distribution and routing decisions are determined simultaneously, implementing a vendor-managed inventory strategy, a difficult combinatorial optimization problem must be solved to determine which customers to visit, how much to replenish, and how to route the vehicles around them. This is known as the inventory-routing problem. We analyze a distribution system with one depot, one vehicle and many customers under the most commonly used inventory policy, namely the (s,S), for different values of s. In this paper we propose three different customer selection methods: big orders first, lowest storage first, and equal quantity discount. Each of these policies will select a different subset of customers to be replenished in each period. The selected customers must then be visited by a vehicle in order to deliver a commodity to satisfy the customers' demands. The system was analyzed using public benchmark instances of different sizes regarding the number of customers involved. We compare the quality and the robustness of our algorithms and detailed computational experiments show that our methods can significantly improve upon existing solutions from the literature
Influence of the pressure dependent coefficient of friction on deep drawing springback predictions
Get PDFThe aim of this work is to show the influence of defining a pressure dependent friction coefficient onnumerical springback predictions of a DX54D mild steel, a HSLA380 and a DP780 high strength steel. Thepressure dependent friction model of each material wasfitted to the experimental data obtained by StripDrawing tests and then implemented in the numerical simulation of an industrial automotive partdrawing process. The results showed important differences between defining a pressure dependent or aconstant friction coefficient. Finally, the experimental part was produced to compare the real geometrywith the predictions obtained with the different simulation strategies. An improvement of 20–25% inspringback prediction was achieved when using the pressure dependent friction model