Numerical analysis for design of bioinspired ceramic modular armors for ballistic protections

[EN] The exigent requirements for personal protections in terms of energy absorption and ergonomics have led to increasing interest in bioinspired protections. This work focuses on the numerical analysis of ballistic behavior of different bioinspired geometries under impact loadings. Ceramic armors based on ganoid fish scales (the type exhibited by gars, bichirs and reedfishes), placoid fish scales (characterizing sharks and rays) and armadillo natural protection have been considered. Different impact conditions are studied, including perpendicular and oblique impacts to surface protection, different yaw angle, and multiple impacts. Main conclusion is related to the improved efficiency of modular armors against multiple shots exhibiting more localized damage and crack arrest properties. Moreover, its potential ergonomic is a promising characteristic justifying a deeper study.The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This work has been carried out within the framework of the research program Juan de la Cierva Incorporacion 2015, and research projects DPI2017-88166-R, and RTC-2015-3887-8 of FEDER program financed by the Ministerio de Economia, Industria y Competitividad of Spain. The support of the Generalitat Valenciana, Programme PROMETEO 2016/007 is also acknowledged.González Albuixech, VF.; Rodríguez-Millán, M.; Ito, T.; Loya, JA.; Miguélez, MH. (2019). Numerical analysis for design of bioinspired ceramic modular armors for ballistic protections. International Journal of Damage Mechanics. 28(6):815-837. https://doi.org/10.1177/1056789518795203S815837286Chen, I. H., Kiang, J. H., Correa, V., Lopez, M. I., Chen, P.-Y., McKittrick, J., & Meyers, M. A. (2011). 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Numerical investigation of the impact behaviour of bioinspired nacre-like aluminium composite plates. Composites Science and Technology, 96, 13-22. doi:10.1016/j.compscitech.2014.03.001Grujicic, M., Pandurangan, B., & Coutris, N. (2011). A Computational Investigation of the Multi-Hit Ballistic-Protection Performance of Laminated Transparent-armor Systems. Journal of Materials Engineering and Performance, 21(6), 837-848. doi:10.1007/s11665-011-0004-3Grunenfelder, L. K., Suksangpanya, N., Salinas, C., Milliron, G., Yaraghi, N., Herrera, S., … Kisailus, D. (2014). Bio-inspired impact-resistant composites. Acta Biomaterialia, 10(9), 3997-4008. doi:10.1016/j.actbio.2014.03.022Klasztorny, M., & Świerczewski, M. (2015). NUMERICAL MODELLING AND VALIDATION OF 12.7 MM FSP IMPACT INTO ALFC SHIELD – ARMOX 500T STEEL PLATE SYSTEM. Journal of KONES. Powertrain and Transport, 19(4), 291-299. doi:10.5604/12314005.1138463Liu, P., Zhu, D., Yao, Y., Wang, J., & Bui, T. Q. (2016). 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Tráficos portuarios por mercancía en España (1995-2010): análisis económico a partir de las importaciones y exportaciones

RESUMEN. En esta investigación se analizan las funciones de demanda de importaciones y exportaciones de los tráficos portuarios españoles por tipo de mercancía según Clasificación Uniforme para el Comercio Internacional (CUCI) de las Naciones Unidas. A partir de un modelo teórico convencional se formulan las hipótesis básicas respecto al comportamiento de la demanda para los precios de las mercancías, los precios del transporte y los diferentes niveles de renta. Después de exponer las fuentes estadísticas de los datos, se estiman las elasticidades respecto al precio de la mercancía, al precio del servicio de transporte marítimo y se realizan una serie de previsiones respecto al comportamiento de la demanda.ABSTRACT. This research analyzes the demand functions for imports and exports for Spanish port traffics by type of goods according to the Standard International Trade Classification (United Nations, 2006). From a conventional theoretical model, the basic hypotheses are formulated regarding the behaviour of the demand for goods prices, transport prices and the different levels of income. After that, the price elasticities are estimated respect to the price of the merchandise, the price of shipping service and income. Finally, a series of provisions regarding the behaviour of demand against the changes in prices and income are mad

Distribución y abundancia de Parastichopus parvimensis (Holothuroidea) en islas de la costa occidental de Baja California Sur, México, durante el periodo reproductivo

The distribution and abundance of the warty sea cucumber Parastichopus parvimensis in the islands Natividad (NI), Asunción (AI) and San Roque (SRI) on the western coast of Baja California Sur (BCS), Mexico, were examined based in independent data from commercial fishing in March and April 2009. The density was estimated from 345 sample units (SU = 10 m2 ) random selected between 2 and 30 m of depth. In NI, AI and SRI was found an average density and standard deviation (S) of 1.1 (1.02), 0.82 (1.06) and 0.83 (0.9) org/m2, and an average gutted weight of 158, 176, and 149g respectively. Changes in density were analyzed using a generalized linear model (GLM) with Gamma error structure, using the variables of depth and zone (islands) as well as the interaction effect, which was significant (p < 0.01). The analysis revealed a pattern of increasing density with the depth in SRI (p < 0.01) and non-significant in NI and AI. The variability of the density was high at all depths in NI (S = 10.2) and AI (S = 10.6), while SRI was only in >10 m depth (S = 9.0), but much less in water shallow (S = 2.7). The way in which the density varies on each island seems to be modulated by physical and biological characteristics related to the substrate, since 85% of the sampling units were associated with rocky substrate. We discuss possible factors that could influence the density changes with depth.Se estudió la distribución y abundancia del pepino de mar Parastichopus parvimensis, utilizando datos independientes de la pesca comercial en las islas Natividad (IN), Asunción (IA) y San Roque (ISR) de la costa occidental de Baja California Sur (BCS), México, en marzo y abril de 2009. La densidad se estimó a partir de 345 unidades de muestra de 10 m2 (UM) distribuidas al azar entre 2 y 30 m de profundidad. En IN, IA e ISR se encontró una densidad promedio y desviación estándar (S) de 1.1 (1.02), 0.82 (1.06) y 0.83 (0.9) org/m2 , y un peso eviscerado promedio de 158, 176, y 149 g respectivamente. Los cambios en densidad se analizaron con un Modelo Lineal Generalizado (MLG) con estructura de error Gamma, en función de las variables de profundidad y zona, así como del efecto de interacción entre ambas, el cual resultó significativo (p < 0.01). El análisis reveló un patrón de densidad creciente con la profundidad en ISR (p < 0.01) y no significativo en IN e IA. La variabilidad de la densidad fue alta en todas las profundidades en IN (S = 10.2) e IA (S = 10.6), mientras que en ISR solamente fue en más de 10 m de profundidad (S = 9.0), y mucho menor en aguas someras (S = 2.7). La forma en que varió la densidad en cada isla, parece estar modulada por características físicas y biológicas relacionadas al sustrato, ya que el 85% de las unidades de muestreo estuvieron asociadas a sustrato rocoso. Se discuten posibles factores que pueden influir en los cambios de la densidad con la profundidad

Análisis numérico de blindajes cerámicos modulares inspirados en la naturaleza para protecciones balísticas

Comunicación presentada en el XXXIV Encuentro del Grupo Español de Fractura celebrado en Santander del 29 al 31 de marzo de 2017.The requirements increase of the protections used by the security forces, which should combine a high capacity for protection and ergonomics, have determined an interest on bioinspired protections. This work presents a numericalstudy numerical of its role performance against impact. We have considered ceramic armours based on ganoid fishscales (gars, bichirs and reedfishes), placoid fish scales (sharks and rays) and armadillos. Perpendicular impacts tosurface protection, oblique and double impacts are considered. It is concluded that the localized damaging and crack arrest properties, associated with its modular configuration, improve their efficiency on multihit situations, besides itspotential ergonomic, convert them in suitable candidates for a deeper study.El aumento en los requerimientos de las protecciones que emplean las fuerzas de seguridad, que deben combinar una alta capacidad de protección y de ergonomía han determinado un creciente interés por el estudio y diseño de protecciones inspiradas en la naturaleza. En este trabajo, se presenta un estudio numérico de la respuesta ante impacto que presentan blindajes cerámicos inspirados en escamas tipo ganoide (esturiones y bichires) y placoide (tiburones y rayas) y la protección de los armadillos. Se consideran impactos perpendiculares a la superficie de protección, oblicuos e impactos dobles. Se concluye que las propiedades de limitar el daño y la fractura asociada a su configuración modular, mejoran su eficacia ante sucesivos impactos, lo que unido a su potencial ergonómico las convierten en candidatas para un estudio más profundo.Los autores desean agradecer, por el soporte económico, al trabajo al programa Juan de la Cierva Incorporación 2015, IJCI-2015-23245 y al proyecto RTC-2015-3887-8 del programa FEDER del Ministerio de Economía, Industria y Competitividad de España

The use of compression stockings during a marathon competition to reduce exercise-induced muscle damage: are they really useful?

OBJECTIVES: To examine the efficacy of wearing compression stockings to prevent muscle damage and to maintain running performance during a marathon competition. BACKGROUND: Exercise-induced muscle damage has been identified as one of the main causes of the progressive decrease in running and muscular performance found during marathon races. METHODS: Thirty-four experienced runners were pair-matched for age, anthropometric data, and best race time in the marathon, and randomly assigned to a control group (n = 17) of runners who wore conventional socks or to a group of runners who wore foot-to-knee graduated compression stockings (n = 17). Before and after the race, a sample of venous blood was obtained, and jump height and leg muscle power were measured during a countermovement jump. Serum myoglobin and creatine kinase concentrations were determined as blood markers of muscle fiber damage

The use of energy drinks in sport: perceived ergogenicity and side effects in male and female athletes

The use of caffeine containing energy drinks has dramatically increased in the last few years, especially in the sport context because of its reported ergogenic effect. The ingestion of low to moderate doses of caffeinated energy drinks has been associated with adverse side effects such as insomnia or increased nervousness. The aim of the present study was to assess psycho-physiological changes and the prevalence of side effects resulting from the ingestion of 3 mg caffeine/kg body mass in the form of an energy drink. In a double-blind and placebo controlled experimental design, ninety experienced and low-caffeine-consuming athletes (fifty-three male and thirty-seven female) in two different sessions were provided with an energy drink that contained 3 mg/kg of caffeine or the same decaffeinated energy drink (placebo; 0 mg/kg). At 60 min after the ingestion of the energy drink, participants completed a training session. The effects of ingestion of these beverages on psycho-physiological variables during exercise and the rate of adverse side effects were measured using questionnaires. The caffeinated energy drink increased self-perceived muscle power during exercise compared with the placebo beverage (6·41 (sd 1·7) v. 5·66 (sd 1·51); P= 0·001). Moreover, the energy drink produced a higher prevalence of side effects such as insomnia (31·2 v. 10·4 %; P0·05). The ingestion of an energy drink with 3 mg/kg of caffeine increased the prevalence of side effects. The presence of these side effects was similar between male and female participants

Efectos de una maratón en valores hematológicos

Introducción: La maratón lleva asociado un estrés fi siológico en el organismo, si bien existe carencia de información sobre cómo afecta a los parámetros sanguíneos en corredores populares y si existe relación con variables de rendimiento, entrenamiento y experiencia deportiva. Propósito: Evaluar los cambios producidos en variables hematológicas en corredores populares tras participar en una maratón en ambiente caluroso. Un segundo objetivo fue analizar la relación entre la experiencia deportiva, el nivel de entrenamiento y el tiempo de carrera con los cambios hematológicos. Métodos: Se extrajo sangre venosa a 41 maratonianos, 35 hombres y 6 mujeres, antes y después de una maratón. Su edad fue de 41,15+8,1 años, y entrenaban como media 55,917,12 kilómetros semanales. El tiempo en meta fue de 3:40:410:32:02. Las muestras fueron medidas con analizadores bioquímicos estándar para determinar los valores de la serie roja y serie blanca

Acute consumption of a caffeinated energy drink enhances aspects of performance in sprint swimmers

This study investigated the effect of a caffeinated energy drink on various aspects of performance in sprint swimmers. In a randomised and counterbalanced order, fourteen male sprint swimmers performed two acute experimental trials after the ingestion of a caffeinated energy drink (3 mg/kg) or after the ingestion of the same energy drink without caffeine (0 mg/kg; placebo). After 60 min of ingestion of the beverages, the swimmers performed a countermovement jump, a maximal handgrip test, a 50 m simulated competition and a 45 s swim at maximal intensity in a swim ergometer. A blood sample was withdrawn 1 min after the completion of the ergometer test. In comparison with the placebo drink, the intake of the caffeinated energy drink increased the height in the countermovement jump (49·4 (SD 5·3) v. 50·9 (SD 5·2) cm, respectively; P<0·05) and maximal force during the handgrip test with the right hand (481 (SD 49) v. 498 (SD 43) N; P<0·05). Furthermore, the caffeinated energy drink reduced the time needed to complete the 50 m simulated swimming competition (27·8 (SD 3·4) v. 27·5 (SD 3·2) s; P0·05). A caffeinated energy drink increased some aspects of swimming performance in competitive sprinters, whereas the side effects derived from the intake of this beverage were marginal at this dosag