The logarithmic spiral, autoisoptic curve

In the Line of Investigation that in the department of “Technical Drawing” in the School of Agriculture Engineering of Madrid, we carry out on the study of The Technical Curves and his singularities, we demonstrate an interesting property of the Logarithmic Spiral. The demonstrated property consists of which the logarithmic spiral is a autoisoptic curve, that is to say that if from a point P anyone of the spiral tangent straight lines draw up to the previous arc, these form a constant angle α. This demonstration is novel and in addition we get to contribute a method to calculate the angle α given the equation of the spiral

Photogrammetry as a New Scientific Tool in Archaeology: Worldwide Research Trends

Archaeology has made significant advances in the last 20 years. This can be seen by the remarkable increase in specialised literature on all archaeology-related disciplines. These advances have made it a science with links to many other sciences, both in the field of experimental sciences and in the use of techniques from other disciplines such as engineering. Within this last issue it is important to highlight the great advance that the use of photogrammetry has brought for archaeology. In this research, through a systematic study with bibliometric techniques, the main institutions and countries that are carrying them out and the main interests of the scientific community in archaeology related to photogrammetry have been identified. The main increase in this field has been observed since 2010, especially the contribution of UAVs that have reduced the cost of photogrammetric flights for reduced areas. The main lines of research in photogrammetry applied to archaeology are close-range photogrammetry, aerial photogrammetry (UAV), cultural heritage, excavation, cameras, GPS, laser scan, and virtual reconstruction including 3D printing

Automation of the shoe last grading process according to international sizing systems

The last is the basic industrial component in footwear manufacturing, from which product development starts. Correct last grading ensures the best fit for the intended group of users of the footwear model to be produced. The size marked on the last should respect the specific intervals defined in the different international sizing systems, like the European, UK, US or Mondopoint systems, which are all described in international standards. New approaches in the field of CAD/CAM have emerged over recent years towards the automation of this process. However, these are partial approaches that neither address the grading process according to the different standards nor consider the various parts of the shoe that are not affected by size increments. This paper presents a new accurate and efficient technique for the automation of the shoe last grading process based on the conjugate gradient method. Through this method, it is possible to obtain a graded shoe last that conforms to the international standards in force relative to shoe sizing and allows for the shoe parts that are not affected by size increments. This technique is based on the target measures of length and perimeter of the last to be graded and aims to minimise the quadratic difference between these values and those obtained from the graded last. This method has been evaluated through a battery of tests performed on a geometrically heterogeneous group of shoe lasts. The results obtained were accurate and the execution time was fast enough to be used for mass production

Nuevo método de cálculo del coeficiente de seguridad de talud, en balsas y presas, mediante la teoría de MOHR-COULOMB

Hasta la fecha y para balsas y presas de uso agrícola, se ha venido utilizando, para el cálculo de este coeficiente de seguridad de talud, el método de las fajas de Fellenius, el cual presenta el inconveniente de los numerosos tanteos que hay que efectuar para poder obtener el coeficiente mínimo de seguridad y la ventaja de que es bastante fiable, sobre todo para presas de tipo homogéneo y heterogéneo. Por este motivo se ha decidido buscar un método alternativo que simplifique enormemente el modus operandi. Para conseguir dicho objetivo, se ha tomado como base la Teoría de Mohr-Coulomb, la cual resuelve el problema de una forma bastante sencilla

In-Field Estimation of Orange Number and Size by 3D Laser Scanning

The estimation of fruit load of an orchard prior to harvest is useful for planning harvest logistics and trading decisions. The manual fruit counting and the determination of the harvesting capacity of the field results are expensive and time-consuming. The automatic counting of fruits and their geometry characterization with 3D LiDAR models can be an interesting alternative. Field research has been conducted in the province of Cordoba (Southern Spain) on 24 ‘Salustiana’ variety orange trees—Citrus sinensis (L.) Osbeck—(12 were pruned and 12 unpruned). Harvest size and the number of each fruit were registered. Likewise, the unitary weight of the fruits and their diameter were determined (N = 160). The orange trees were also modelled with 3D LiDAR with colour capture for their subsequent segmentation and fruit detection by using a K-means algorithm. In the case of pruned trees, a significant regression was obtained between the real and modelled fruit number (R2 = 0.63, p = 0.01). The opposite case occurred in the unpruned ones (p = 0.18) due to a leaf occlusion problem. The mean diameters proportioned by the algorithm (72.15 ± 22.62 mm) did not present significant differences (p = 0.35) with the ones measured on fruits (72.68 ± 5.728 mm). Even though the use of 3D LiDAR scans is time-consuming, the harvest size estimation obtained in this research is very accurate

Repercusión del empleo de la proyección UTM en el cálculo de la superficie de fincas

La representación de la Tierra o de una parte de ella lleva asociada una serie de limitaciones. La forma y dimensiones de la misma hacen que, cuando se trata de representar de forma métrica un territorio de cierta extensión, haya que trabajar con sistemas y superficies de referencia (elipsoides, esferas, etc.), así como con sistemas de representación o cartográficos (proyecciones cartográficas como UTM, Lambert, etc.). El hecho de trabajar con programas informáticos cada vez más potentes no debe enmascarar el trasfondo de conocimientos necesarios para dar resultados lo más correctos posibles o, en cualquier caso, saber qué limitaciones tiene el resultado aportado. El empleo de sistemas de representación conlleva una deformación (anamorfosis) aun cuando las proyecciones utilizadas son generalmente conformes (las formas se mantienen, pero no así las distancias – anamorfosis lineal– ni las superficies), por lo que esto deriva en que el valor de las distancias y superficies se ve alterado, siendo este valor el proporcionado por los programas de cálculo. En este trabajo, se analiza la repercusión de la ubicación de una finca en el cálculo de la superficie de la misma, cuando se trabaja con la proyección UTM, frente al valor que podría considerarse “sin deformación” a través de una serie de ejemplos.Representation of the Earth or a part of the same implies some restrictions. Its shape and size mean that, when representing a territory of a certain size in a metric manner, reference systems and surfaces must be used (ellipsoids, spheres, etc.), as well as representation or cartographic systems (cartographic projections such as UTM, Lambert, etc.). The use of increasingly powerful computer programs must not mask the background of knowledge that is necessary in order to reach the most accurate results possible or, in any case, to understand the limitations of the results obtained. The use of representation systems involves deformation (distortion) even when the projections used generally conformal (the shapes are maintained, but distances (lineal distortion) and surfaces are not), which leads to alteration of the values of the distances and surfaces, with this value being provided by the calculation programs. This work analyzes the impact of the location of an estate when calculating the surface of the same with UTM projection, in comparison with the value that could be considered "deformation-free" through a series of examples

Optimal design of prestressed concrete hollow core slabs taking into account its fire resistance

[EN] Prestressed hollow core slabs are a concrete element widely used as construction floor product, which manufacturing process has greatly been improved in recent years. Several research studies focused on hollow core slab performance, mainly related to its fire behavior, have provided new limit states to be assessed throughout its life cycle. Therefore, the hollow core slab design needs to be reviewed to allow for these improvements, a process which may involve changes to its geometry. In order to deal with this review, modern computational optimization techniques offer an alternative approach to traditional structural product design procedure, mainly based on the engineer's prior experience. This paper proposes a hollow core slab model (including variables and constraints) to develop heuristic search algorithms, such as simulated annealing, in order to find the most economical slab design including the fire resistant constraint and taking into account all available manufacturing technologies. The optimal designs obtained by this process save up to 20% in cross-section area compared with common circular void designs from market, which is taken as a comparison pattern. The results show that traditional designs are deficient when the fire resistant constraint is considered, so that precast manufacturers and machinery designers should use optimization techniques to modify their hollow core slab geometry.Albero Gabarda, V.; Saura Arnau, H.; Hospitaler Pérez, A.; Montalva Subirats, JM.; Romero, ML. (2018). Optimal design of prestressed concrete hollow core slabs taking into account its fire resistance. Advances in Engineering Software. 122:81-92. doi:10.1016/j.advengsoft.2018.05.001S819212

Caracterización de electrolitos poliméricos basados en líquidos iónicos y diferentes concentraciones de ZnTf2 para su uso en baterías de Zn

Se han sintetizado membranas de electrolito polimérico compuestas de poli (fluoruro de vinilideno-co-hexafluoropropeno) (PVdF-HPF), un liquido iónico (1-etil-3-metilimidazolio bis (trifluorometilsulfonil) imida [EMIM]+ [TFSI]-) y diferentes concentraciones de sal de trifluorometanosulfonato de Zinc (ZnTf2). Además se caracterizaron utilizando técnicas experimentales como difracción de Rayos X (DRX), Espectroscopía de Infrarrojo (FTIR), y por último se realizó un estudio de la conductividad iónica con la temperatura donde se obtuvo que el polielectrólito sigue un comportamiento tipo Arrhenius, lo que nos permite obtener los valores de Energía de activación para cada una de las membranas compuestas por diferentes concentraciones de sal.Centro Universitario de la Defensa. Escuela de Turismo de Cartagena. Escuela Técnica Superior de Ingeniería Industrial UPCT. Escuela Técnica Superior de Ingeniería de Telecomunicación (ETSIT). Escuela de Ingeniería de Caminos y Minas (EICM). Escuela de Arquitectura e Ingeniería de Edificación (ARQ&IDE). Parque Tecnológico de Fuente Álamo. Navantia. Campus Mare Nostrum. Estación Experimental Agroalimentaria Tomás Ferr

Graphene Derivatives: Controlled Properties, Nanocomposites, and Energy Harvesting Applications

Graphene is a ground‐breaking two‐dimensional (2D) material that possesses outstanding electrical, optical, thermal, and mechanical properties and that promises a new generation of devices. Despite all these, some applications require graphene‐based materials with different characteristics, such as good solubility in organic solvents and a specific band gap to be dispersible in polymer nanocomposite matrix and applied as active layer, electron transport layer (ETL) or hole transport layer (HTL) in organic photovoltaics. Chemically modified graphene derivatives are studied, searching for better dispersions and even more properties for different applications. Most of the attention has been drawn to dispersions of graphene oxides or highly reduced graphene oxides. Therefore, this allows an opportunity to study the characteristics of materials with intermediate oxidation degrees and its applications

Implementation of Project-Based Learning at a Multidisciplinary Level of the Specialization in Design and Manufacture of Machines and Prototypes in the Degree of Mechanical Engineering

[EN] Since the implementation of the Bologna Process, universities have been incorporating into the European Higher Education Area, adapting and unifying educational criteria for all the European centers. Although mobility and bilingualism have been clearly promoted in universities by increasing performance in certain areas, it is necessary to improve other areas such as the implementation of novel active learning methodologies to promote deep learning. For this reason, Universitat Politècnica de València is putting faith in the implementation of active methodologies that integrate the development and acquisition of competences making the students the center of the learning-teaching process. Moreover, the lack of coordination among different subjects of the specialization in design and manufacture of machines and prototypes in the degree of Mechanical Engineering, is another important issue to be considered as it makes students to find difficulties in solving real problems. In light of all these identified difficulties, the objective of this work is to design a project-based learning (PBL) model among the different subjects of the aforementioned specialization. The use of PBL will make students to actively participate in higher-level of cognitive processes. The most important premise when designing the project, in this case a gearbox casing, is the multidisciplinary aspects as the same project will have continuity and will cover different contents throughout the different subjects in the specialization. The methodology used for defining and implementing the PBL model consists of: (i) the identification of the current main difficulties; (ii) the definition of the PBL model; (iii) the identification of the necessary contents per subject to be applied in the solving process of the PBL model; and (iv) the evaluation/assessment of the PBL model implementation. Finally, both the project and the different activities to be carried out in the different subjects involved in the PBL model are presented. In addition, the results obtained through a satisfaction survey performed by the students to collect their opinion will be also analysed to provide feedback for further improvement of the PBL model.This article has been supported by Universitat Politècnica de València, particularly by the Vice-rectorate for Digital Resources and Documentation (Vicerrectorado de Recursos Digitales y Documentación) and Vice-Rectorate for Studies, Quality and Accreditation (Vicerrectorado de Estudios, Calidad y Acreditación) under the Call for Learning + Teaching (Convocatoria A+D2019: Aprendizaje + Docencia. Proyectos de Innovación y Mejora Educativa) and Project Code: A157. The authors would like to acknowledge the support of the Institute of Educational Sciences (Instituto de Ciencias de la Educación), the Evaluation and Monitoring Commission for Educational Innovation and Improvement Projects (Comisión de Evaluación y Seguimiento de Proyectos de Innovación y Mejora Educativa (CESPIME) and Escuela Politécnica Superior de AlcoyMontava-Jorda, S.; Colomer Romero, V.; Martínez Sanz, AV.; Reig-Pérez, MJ.; López Esteve, FM. (2021). Implementation of Project-Based Learning at a Multidisciplinary Level of the Specialization in Design and Manufacture of Machines and Prototypes in the Degree of Mechanical Engineering. EDULEARN Proceedings (Internet). 7477-7483. https://doi.org/10.21125/edulearn.2021.1518S7477748