Two-Dimensional-Based Hybrid Shape Optimisation of a 5-Element Formula 1 Race Car Front Wing under FIA Regulations

Front wings are a key element in the aerodynamic performance of Formula 1 race cars. Thus, their optimisation makes an important contribution to the performance of cars in races. However, their design is constrained by regulation, which makes it more difficult to find good designs. The present work develops a hybrid shape optimisation approach to obtain an optimal five-element airfoil front wing under the FIA regulations and 17 design parameters. A first baseline design is obtained by parametric optimisation, on which the adjoint method is applied for shape optimisation via Mesh Morphing with Radial Basis Functions. The optimal front wing candidate obtained outperforms the parametric baseline up to a 25% at certain local positions. This shows that the proposed and tested hybrid approach can be a very efficient alternative. Although a direct 3D optimisation approach could be developed, the computational costs would be dramatically increased (possibly unaffordable for such a complex five-element front wing realistic shape with 17 design parameters and regulatory constraints). Thus, the present approach is of strong interest if the computational budget is low and/or a fast new front wing design is desired, which is a frequent scenario in Formula 1 race car design.The authors want to acknowledge the financial support from the Ramón y Cajal 2021 Excellence Research Grant action from the Spanish Ministry of Science and Innovation (FSE/AGENCIA ESTATAL DE INVESTIGACIÓN), the UMA18-FEDERJA-184 grant, and the Andalusian Research, Development and Innovation Plan (PAIDI—Junta de Andalucia) fundings. Partial funding for open access charge: Universidad de Málag

One-Step Enameling and Sintering of Low-Carbon Steels

This article belongs to the Section Powder MetallurgyPowder technology allows manufacturing complex components with small tolerances, saving material without subsequent machining. There is a growing trend in using sintered steel components in the automotive industry. Within 2020, about 2544 million US dollars was invested for manufacturing sintered components. Not only does this industry uses steel components, but the gas cooker industry also uses steel in its burners since they are robust and usually demanded by Americans, with forecasts of 1097 million gas cookers in 2020. Steel gas burners have a ceramic coating on their surface, which means that the burner is manufactured in two stages (casting and enameling). This work aims to manufacture the gas burners by powder metallurgy, enameling and sintering processes in a single step. To achieve this aim, the ASC100.29 iron powder has been characterized (flow rate, relative density and morphology); subsequently, the most suitable parameters for its compaction and an adequate sintering temperature were studied. Single-step sintering and enameling was achieved by compacting iron powder at 500 MPa and sintering at 850 °C for 5 min. The necessary porosity for mechanical anchoring of the coating to the substrate is achieved at this sintering temperature. Bending resistance tests, scratching, degradation under high temperature and basic solution and scanning electron microscopy were used to characterize and validate the obtained samples

Sensitivity analysis of a member under compression via Monte Carlo method

The present work studies the application of a probabilistic methodology in the sensitivity analysis of a steel column to identify the dominant parameters in its load capacity. Monte Carlo type simulations, in combination with the finite element method, was carried out to achieve the proposed objective. The geometric nonlinearity in the model was considered in order to reflect large deflections and initial geometric imperfections. The results show that the sensitivity of the column to a specific input parameter depends on the slenderness ratio and, hence, the column will be more sensitive to one parameter or another depending on that relationship.En este trabajo se presenta un estudio probabilístico para el análisis de sensibilidad de una columna de acero, con el fin de identificar los parámetros que más afectan su capacidad de carga. Se llevaron a cabo simulaciones tipo Monte Carlo, en combinación con simulaciones numéricas, mediante el uso del método de elementos finitos. En el modelo numérico, se consideró la no linealidad geométrica, con el objeto de considerar grandes desplazamientos e imperfecciones geométricas iniciales. Los resultados muestran que la sensibilidad de la columna a una variable de entrada específica depende de la relación de esbeltez, y, por lo tanto, la columna será más sensible a una variable u otra en función de esa relación

Thermal characterization and diffusivity of two mono-component epoxies for transformer insulation

The main aim of this study is the thermal characterization of an organic insulation. This insulation is a compound of two mono-component epoxy resins: Epoxylite® primer and Elmotherm® varnish. A mono-component epoxy resin usually needs a high temperature to cure; through differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA), non-isothermal curves are obtained, allowing the estimation of activation energies of curing and decomposition processes respectively. If Model Free Kinetic (MFK) is used from DSC curves, it is possible to simulate isothermal curves at different temperatures and times, plotting activation energy as a function of the conversion degree. The simulation from TGA curves can be used to estimate lifetime of the resins and compare them following the Toop method. DSC also allows measurement of thermal conductivity, the melting peak of metallic gallium being used for this measurement. Finally, water diffusion in resins is studied. Currently, the Materials Performance research group of UC3M is working on the European project named "Essial", where this organic insulation is used to protect the windings and the whole transformer from the environment. The results obtained will be used to determinate the optimal operating range for this insulator, demonstrating that both epoxies are required to achieve the insulating performance of the transformer and long curing times are required for full curing of Epoxylite®.This research was funded by European Union's Horizon 2020 research and innovation programme under grant agreement No 766437 (ESSIAL project)

Estimation of the aerodynamic tortuosity of woven/wire screens

The use of wire/woven screens (WSs) is frequent in applications such as particle or insect-proof screen in home/greenhouse/farm with natural ventilation. Although this passive element has been studied for decades, most previous works have focused on relating the airflow performance only to porosity. However, most recent investigations have demonstrated that other pore-related parameters such as constriction factor and tortuosity are necessary for the characterisation of screens. Tortuosity of WSs is a parameter that has been broadly estimated in the literature, whose calculations to date are not physics-based and yield a constant value without dependence on airflow velocity. The present investigation proposes a novel method to calculate tortuosity of WS. The new approach uses the flow potential flow theory to estimate realistic curvatures of the streamlines around the inclined threads of the WS. The calculated tortuosity has been made also velocity-dependent, because its value changes for Reynolds numbers below 200, generally. The accurate estimation of tortuosity is a very important contribution to the field, because it is a missing link to develop a universal model to estimate pressure drop for any WS performance. This calculation has been added to AeroScreen software, which allows to obtain porosity, constriction and tortuosity from geometry data

The Use of Silica Microparticles to Improve the Efficiency of Optical Hyperthermia (OH)

Although optical hyperthermia could be a promising anticancer therapy, the need for high concentrations of light-absorbing metal nanoparticles and high-intensity lasers, or large exposure times, could discourage its use due to the toxicity that they could imply. In this article, we explore a possible role of silica microparticles that have high biocompatibility and that scatter light, when used in combination with conventional nanoparticles, to reduce those high concentrations of particles and/or those intense laser beams, in order to improve the biocompatibility of the overall procedure. Our underlying hypothesis is that the scattering of light caused by the microparticles would increase the optical density of the irradiated volume due to the production of multiple reflections of the incident light: the nanoparticles present in the same volume would absorb more energy from the laser than without the presence of silica particles, resulting either in higher heat production or in the need for less laser power or absorbing particles for the same required temperature rise. Testing this new optical hyperthermia procedure, based on the use of a mixture of silica and metallic particles, we have measured cell mortality in vitro experiments with murine glioma (CT-2A) and mouse osteoblastic (MC3T3-E1) cell lines. We have used gold nanorods (GNRs) that absorb light with a wavelength of 808 nm, which are conventional in optical hyperthermia, and silica microparticles spheres (hereinafter referred to as SMSs) with a diameter size to scatter the light of this wavelength. The obtained results confirm our initial hypothesis, because a high mortality rate is achieved with reduced concentrations of GNR. We found a difference in mortality between CT2A cancer cells and cells considered non-cancer MC3T3, maintaining the same conditions, which gives indications that this technique possibly improves the efficiency in the cell survival. This might be related with differences in the proliferation rate. Since the experiments were carried out in the 2D dimensions of the Petri dishes, due to sedimentation of the silica particles at the bottom, whilst light scattering is a 3D phenomenon, a large amount of the energy provided by the laser escapes outside the medium. Therefore, better results might be expected when applying this methodology in tissues, which are 3D structures, where the multiple reflections of light we believe will produce higher optical density in comparison to the conventional case of no using scattering particles. Accordingly, further studies deserve to be carried out in this line of work in order to improve the optical hyperthermia technique.This study was partially supported by CIBER-BBN (Spain) and the NEUROCENTRO-CM (B2017/BMD-3760) Consortium. Characterization of the MNPs was performed by the ICTS ‘NANBIOSIS’, Unit 15, Functional Characterization of Magnetic Nanoparticles of the CIBER in Bioengineering, Biomaterials & Nanomedicine (CIBER-BBN) at the Center for Biomedical Technology (CTB) of the ‘Universidad Politécnica de Madrid’ (UPM). This work was carried out as a part of Project PGC2018-097531-B-I00, funded by the Ministry of Science of Spain

Semi-Analytical Calculation of Pore-Related Parameters of Wire/Woven Screens

Wire/woven screens have a wide range of applications, from being used as simple mechanical screening device to nanoscreen wicking with nanofluids. The vast number of applications makes important to study these screens with high accuracy, to reduce errors in characterisation and performance predictions. Previous works to date focused either on the study of these screens as a two-dimensional surface (e.g. in ventilation openings as insect-proof screens) or as three-dimensional structures under important assumptions (symmetric mesh, thickness of two times their diameter, linear evolution of the pore area along the thickness). These incomplete modellings introduce errors in applications such as the estimation of permeability of the porous media (two-dimensional porosity is identical for two meshes with the same projected area of pore but different thickness) or computational simulations of ventilation in buildings/greenhouses, where these parameters are imposed as boundary condition. The present investigation shows a method to calculate three-dimensional pore related structural properties semi-analytically for the first time and for any plain square mesh. We found that when sweeping the mesh with a plane parallel to it there are up to six different zones or stretches which can be integrated by a piece-wise approach (here named Discretisation Method). Results demonstrated high accuracy in the calculation of three-dimensional porosity and constriction factor (a parameter that is calculated by integration over the pore volume). Due to the mathematical complexity in the method, a software (AeroScreen v1.0) is available to obtain pore-related structural parameters from diameters, separations and thickness of the screen

Mechanical properties and fire-resistance of composites with marble particles

The main aim of this work is to manufacture a composite material based on a natural material (marble) with acceptable mechanical properties and fire resistance, for being used in habitat industry as floor or wall in buildings. Marble used as raw material is the waste powder of quarry or plate manufacturing. To achieve this objective, polyester matrix composites with 50 wt.% of marble and 3 wt.% of glass fiber (short fiber or mesh) were prepared. The novelty of this study is the high percentage of ceramic material added to a polymer matrix composite and the fire resistance study. Samples were characterized mechanically through flexural test, Charpy impact test, compression test and wear resistance by pin-on-disk test. Fracture surfaces were analyzed by scanning electron microscope (SEM), and wear tracks were studied by SEM and 3D optical profilometer. Besides, samples were subjected to fire test using a Bunsen burner at 900 °C for 20 min. Sample temperature at the opposite-to-fire test side was measured with an infrared thermometer. Results show that marble improves mechanical properties of polyester and the effect of the glass fiber depends on its morphology (fiber or mesh). Fire resistance is high, and the fire goes out when the flame is turned off. Furthermore, the mesh maintains the integrity of the sample.This research received funding from the SUDOE project SOE1/P1/E307

2nd National Study of Pressure Ulcer Prevalence in Spain, 2005: epidemiology and definitory wound and patient variables

Desde el año 1999 el GNEAUPP consideró de vital interés para rescatar y mantener el valor real del problema de las úlceras por presión (UPP), la constitución de un observatorio permanente de la evolución epidemiológica de estos procesos, cuyo siguiente paso ha sido el desarrollo de este 2º Estudio Nacional de Prevalencia que presentamos. Se definieron como objetivos de la investigación obtener indicadores epidemiológicos que permitiesen dimensionar el problema de las UPP en España, así como algunos aspectos relacionados con las tendencias de prevención de las mismas en instituciones de Atención Primaria, atención hospitalaria y asistencia sociosanitaria. Elaboramos un cuestionario postal para estimar la prevalencia puntual y media de UPP a partir de una muestra no aleatoria. En estos cuestionarios se solicitaba a los profesionales de Atención Primaria que informasen acerca de su lista de usuarios mayores de 14 años (Unidades básicas asistenciales de Medicina General) y a los profesionales de unidades de hospitalización o de centros sociosanitarios que informasen acerca de los pacientes de sus respectivas unidades. Se definió la prevalencia como “prevalencia puntual” (información en un solo momento del tiempo). Se calculó la prevalencia cruda (PC) y media (PM). Los cuestionarios contenían preguntas para obtener datos sobre los pacientes con UPP (numerador del indicador), sobre el total de pacientes de esa unidad a estudio (denominador del indicador), sobre las lesiones mismas, así como información de las tendencias de prevención de UPP en las instituciones de los receptores de los cuestionarios. Se reportaron 1.791 pacientes con UPP (39% en hospital, 27% en Atención Primaria y 34% en centros sociosanitarios). En Atención Primaria la PC fue de 3,73% y la PM de 9,11% ± 10,9% para los pacientes mayores de 14 años incluidos en el programa de atención domiciliaria; en las unidades de hospital, la PC fue de 8,24% y la PM de 8,91% ± 12,20%, y en los centros sociosanitarios la PC fue de 6,10% y la PM de 10,9% ± 11,9%. En todos los niveles asistenciales, el grupo de población mayoritariamente afecto era el de los mayores de 65 años (84,7%). Los cuestionarios recibidos proporcionaron información sobre 2.837 lesiones: 23,2% de estadio I, 37,5% de estadio II, 27,0% de estadio III, 11,8% de estadio IV y un 0,5% sin estadiar. La localización más frecuente fue el sacro seguido de los talones, en todos los niveles asistenciales. Puede concluirse que las UPP siguen constituyendo, todavía, un importante problema de salud pública que afecta de manera primordial a personas mayores.Since 1999, GNEAUPP considered it vital to create a permanent observatory of the epidemiological evolution of these processes, in order to rescue and maintain the real value of the problem of Pressure Ulcers, which has given way to the next step, the 2nd National Prevalence Study we now present. The objectives set forth in this study were to obtain epidemiological indicators that would allow us to find the extent of the pressure ulcer problem in Spain, as well as some aspects related to the prevention of such in primary care centers, hospitals and socio-sanitary institutions. We sent out a questionnaire in order to estimate the punctual and average prevalence of PU (initials UPP in Spanish) using non-random sampling. Primary Care professionals were asked to give information about their patients who were over 14 years of age (General Practitioner Surgeries) and professionals from Hospital Units and socio-sanitary centers were asked about their patients respectively. Prevalence was defined as ‘punctual prevalence’ (information in a specific moment in time). The crude prevalence (initials PC in Spanish) and average prevalence (PM) were calculated. The questionnaires only included questions on patients with PU (numerator of the indicator) over the total of patients of the unit being studied (denominator of the indicator) about the wounds caused as well as information on PU prevention in the institutions where each respondant worked. 1,791 patients were reported to have pressure ulcers (39% in hospital, 27% in primary care centers and 34% in socio-sanitary centers). In Primary Care, the PC was 3.73% and the PM was 9.11% ± 10.9% for patients over 14 years who were included in the home care program. In the hospital units, the PC was 8.24% and the PM was 8.91% ± 12.20% and in the socio-sanitary centers, the PC was 6.10% and the PM was 10.9% ± 11.9%. The group most affected of each health care level was the one over 65 years of age (84.7%). The completed questionnaires provided information about 2,837 wounds: 23.2% were stage I, 37.5% stage II, 27.0% stage III, 11.8% stage IV and 0.5% did not state the stage. PU most frequently affected the sacral region, followed by the heels, in all health care levels. It can be concluded that PU are still an important public health problem that affect mainly elderly people