Analytical modelling of normal and oblique ballistic impact on ceramic/metal lightweight armours

This paper presents a new analytical model developed to simulate ballistic impact of projectiles on ceramic/metal add-on armours. The model is based on Tate and Alekseevskii’s equation for the projectile penetration into the ceramic tile, whilst the response of the metallic backing is modelled following the ideas of Woodward’s and den Reijer’s models. The result is a fully new analytical model that has been checked with data of residual mass and residual velocity of real fire tests of medium caliber projectiles on ceramic/metal add-on armours. Agreement observed between experimental and analytical results confirmed the validity of the model. Therefore, the model developed can be a useful tool for optimisation of ceramic/metal armour design.The authors are indebted to the Research & Development Department of Empresa Nacional Santa Bárbara (Spain) for the performance of the ballistic tests and the X-ray shadowgraphs. This work is part of the EUCLID RTP 3.2 project, supported by the Ministries of Defence of Spain, Denmark, Holland and Italy. The above project has been developed with the collaboration of several companies and research centres of the aforementioned countries.Publicad

Modelling the fracture processes in the ballistic impact on ceramic armours

6 pages, 6 figures.-- Issue title: "EURODYMAT 1997 - 5th International Conference on Mechanical and Physical Behaviour of Materials under Dynamic Loading".-- Published in: Colloque C3, Supplement au Journal de Physique III d'août 1997.[EN] This work examines the essential physical processes in the perforation of metal backed ceramic armours which include projectile erosion, fracture of the ceramic tile and ductile deformation of the metal backing plate. The impact of projectiles onto alumina and aluminium nitride ceramic materials is studied experimentally and numerically. Observations were performed using an X-ray shadowgraph technique to obtain accurate data of the penetration process at different times. From the examination of computer simulations and corresponding impact experiments a simple analytical model is developed by assuming some hypotheses simplifying the actual mechanisms of the penetration process. Material description is simplified by using simple equations and a few material parameters easily obtained experimentally, such as the elastic modulus, the compressive and tensile strength and the rupture strain.[FR] Ce travail examine les procès physiques essentiels qui concernent la perforation des blindages céramique/métal en incluant dans un modèle analytique l'érosion du projectile, la fracture de la céramique et la déformation plastique de la plaque métallique. L'impact de projectiles sur des plaques d'oxide d'aluminium et de nitrure d'aluminium est étudié expérimentale et numériquement. Pour obtenir les donnés expérimentales un appareil photographique à rayons X a été utilisé, permettant observer avec précision le procès de pénétration. À partir de l'analyse des simulations numériques et des données expérimentales un modèle analytique a été développé en assumant une grande simplification des mécanismes de perforation. Le comportement mécanique des matériaux est simplifié en faisant appel à des équations constitutives simples avec quelques paramètres facilement accessibles expérimentalement comme le module d'élasticité, la résistance à compression et la déformation maximale.The authors are indebted to the Research & Development Department of Empresa Nacional Santa Bárbara (Spain) for the performance of the ballistic tests and the obtention of the X-ray shadowgraphs. This work is a part of the EUCLID RTP 3.2 project, supported by the Ministries of Defence of Spain, Denmark, Holland and Italy. The above project is being developed with the collaboration of several companies and research centres of the aforementioned countries.Publicad

Using an analytical model of simulation in the design of light-weight armours

9 pages, 13 figures.This paper presents a model for the simulation of the impact of projectiles of high kinetic energy on lightweight ceramic/metal armours. The work was financed jointly by the Defence Ministries of Spain, Italy, Holland and Denmark as part of a project among nations for the development of tools for the design of this type of armour. The model consists of a series of differential equations incorporating the most essential phenomena of the impact process, formulated after a close study of a series of real fire tests. It features a nucleus of calculation into which the equations may in time be integrated, and may also include a user interface. This practical, preliminary design tool's efficacy is amply confirmed by test results.The authors are indebted to the Research & Development Department of Empresa Nacional Santa Bárbara (Spain) for the performance of the ballistic tests and the X-ray shadowgraphs. This work is part of the EUCLID RTP 3.2 project, supported by the Ministries of Defence of Spain, Denmark, Holland and Italy. The above project has been developed with the collaboration of several companies and research centres of the aforementioned countries.Publicad

Fundamentos de los procedimientos de regeneración: regeneración tisular guiada, regeneración ósea guiada

Múltiples factores y / o condiciones tales como enfermedades periodontales, traumatismos, anomalías congénitas y tumores pueden dar como resultado una pérdida significativa del periodonto y las estructuras circundantes. Si no se proporciona tratamiento, entonces aumenta el riesgo de defectos óseos extensos y esto puede eventualmente comprometer la capacidad de mantener la dentadura o incluso la estructura ósea en general para la futura rehabilitación protésica.Multiple factors and / or conditions such as periodontal diseases, trauma, congenital anomalies and tumors can result in a significant loss of period and surrounding structures. If it is not a treatment, then the risk of defects increases. This can occasionally compromise the ability to maintain the denture or even the physical structure in general for future prosthetic rehabilitatio

Indicadores de gestión del capital intelectual para la banca comercial cubana

Aim: To establish indicators of management of intellectual capital in the framework of Cuban commercial banking. Methods: The methodology of logical approach, consisting in the definition of moments and steps that ensure the design of indicators to measure management of intellectual capital in this sector. Besides, mathematical and statistical methods were applied, along with experimental empirical methods, expert opinion, and content analysis. Main results: To provide the Cuban banking sector with a system of indicators customized to the current development trends, in keeping with international practice. Conclusions: From the total number of 58 indicators (30 quantitative and 28 qualitative), 55 were selected. Although the intellectual capital tends to mix (due to its basically intangible character) with human capital, the structural capital comprised most indicators. This study corroborates the banking trend toward quality and diversification of processes and products through excellence in innovation.Objetivo: Elaborar indicadores para la medición de la gestión del capital intelectual, contextualizados en los bancos comerciales cubanos. Métodos: Se aplicó la metodología del enfoque del marco lógico, consistente en la definición de momentos y pasos que, con una secuencia lógica, posibilitó el diseño de los indicadores de medición de la gestión del capital intelectual para este sector. Se aplicaron métodos estadísticos matemáticos, empíricos experimentales, criterio de expertos y análisis de contenido. Principales resultados: Dotar al sector bancario cubano de un sistema de indicadores contextualizado en sus tendencias actuales de desarrollo y en correspondencia con las prácticas internacionales. Conclusiones: Se propusieron 58 indicadores (30 cuantitativos y 28 cualitativos); de estos los expertos dejaron 55, donde —a pesar de que el capital intelectual tiende a confundirse (por su carácter netamente intangible) con el capital humano—, el componente capital estructural posee la mayor cantidad de indicadores. Se reafirma así la tendencia de la banca hacia la calidad y diversificación de los procesos y productos bancarios, potenciados a través de innovación de excelencia

Búsqueda de modelos QSAR para la actividad repelente de sesquiterpenos naturales frente al mosquito de la Fiebre Amarilla, Aedes aegypti

El objetivo de este trabajo ha sido desarrollar modelos QSAR aplicando la topología molecular y el análisis de regresión multilineal para la predicción de la repelencia espacial frente al mosquito de la Fiebre Amarilla,  Aedesa egypti  de un grupo de sesquiterpenos naturales. Validados los modelos, se realiza un cribado molecular y se seleccionan nuevos sesquiterpenos potencialmente activos

Calibration transfer and drift counteraction in chemical sensor arrays using Direct Standardization

Inherent variability of chemical sensors makes it necessary to calibrate chemical detection systems individually. This shortcoming has traditionally limited usability of systems based on metal oxide gas sensor arrays and prevented mass-production for some applications. Here, aiming at exploring calibration transfer between chemical sensor arrays, we exposed five twin 8-sensor detection units to different concentration levels of ethanol, ethylene, carbon monoxide, or methane. First, we built calibration models using data acquired with a master unit. Second, to explore the transferability of the calibration models, we used Direct Standardization to map the signals of a slave unit to the space of the master unit in calibration. In particular, we evaluated the transferability of the calibration models to other detection units, and within the same unit measuring days apart. Our results show that signals acquired with one unit can be successfully mapped to the space of a reference unit. Hence, calibration models trained with a master unit can be extended to slave units using a reduced number of transfer samples, diminishing thereby calibration costs. Similarly, signals of a sensing unit can be transformed to match sensor behavior in the past to mitigate drift effects. Therefore, the proposed methodology can reduce calibration costs in mass-production and delay recalibrations due to sensor aging. Acquired dataset is made publicly available

Aplicación de la topología molecular para la predicción de biodegradación anaerobia de clorofenoles

Se ha aplicado la topología molecular y el análisis de regresión multilineal en la búsqueda de un modelo de relación cuantitativa estructura-actividad (QSAR) capaz de predecir la capacidad de biodegradación anaerobia de un grupo de clorofenoles. Tomando el valor de la constante de velocidad de desaparición del derivado clorofenólico ,log k, como variable dependiente y los descriptores topológicos como variables independientes, se obtuvo una ecuación con tres variables y coeficientes de correlación y de predicción , R2=0.9291 y Q2=0.870. El modelo fue validado a través de una validación interna y un test de aleatoriedad. Los resultados obtenidos muestran una alta capacidad de predicción para la biodegradación de los compuestos analizados

Short Wave Ultraviolet Light (UV-C) Effectiveness in the Inactivation of Bacterial Spores Inoculated in Turbid Suspensions and in Cloudy Apple Juice

Liquid foods might present interferences in their optical properties that can reduce the effectiveness of short-wave ultraviolet radiation (UV-C) treatments used for sterilization purposes. The effect of turbidity as UV-C interference factor against the inactivation of bacterial spores was analysed by using phosphate-buffered saline solutions (PBS) of different turbidity values (2000, 2500, and 3000 NTU) which were adjusted with the addition of apple fibre. These suspensions were inoculated with spores of Bacillus subtilis and Alicyclobacillus acidoterrestris. While higher UV-C doses increased the inactivation rates of spores, these were reduced when turbidity values increased; a dose of 28.7 J/mL allowed inactivation rates of B. subtilis spores of 3.96 Log in a 2000-NTU suspension compared with 2.81 Log achieved in the 3000-NTU one. Spores of B. subtilis were more UV-C-resistant than A. acidoterrestris. Cloudy apple juice inoculated with A. acidoterrestris spores was processed by UV-C at different doses in a single pass and with recirculation of the matrix through the reactor. Inactivation increased significantly with recirculation, surpassing 5 Log after 125 J/mL compared with 0.13 Log inactivation after a single-pass treatment at the same UV-C dose. UV-C treatments with recirculation affected the optical properties (absorption coefficient at 254 nm and turbidity) of juice and increased browning as UV-C doses became higher

Analysis and evaluation of the operational characteristics of a new photodynamic therapy device

One of the key aspects of photodynamic therapy is the light source that is used to irradiate the lesion to be treated. The devices used must ensure that their emission spectrum matches the absorption spectrum of the photosensitizer, so that treatment radiation is delivered only on the target area, without irradiating healthy tissue at superficial or deep levels. Irradiance values must be adequate in order to avoid thermal damage, exceed the oxygen replenishment rate and avoid long treatment times. Furthermore, the device should be user-friendly, inexpensive, and able to be adapted to different photosensitizers. We have developed an easy-to-use and highly customizable device based on LED technology. Its innovative geometric design allows radiation to be delivered to a small treatment surface, since the LEDs are arranged in three arms, the configuration of which directs their radiation on the treatment point. Different high-power color LEDs are disposed on the arms, and can be independently selected based on the most effective wavelengths for exciting the different photodynamic therapy photosensitizers. We have tested the prototype in 5 different patients (1 actinic keratose, 1 actinic cheilitis, 1 superficial basal cell carcinoma and 2 Bowen's disease) and after 1-2 sessions of total cumulative dose of 25-50 J / cm2, 100% clearance of lesions were obtained. Our device can be used by any professional in the field, whether for medical or research purposes. It facilitates the development of treatment protocols and trials with different photosensitizers