Evolución de la planta de concentración de la mina de estaño "El cubito" Salamanca

[Resumen] Durante los últimos diez años la mina de estaño "El Cubito", en la provincia de Salamanca, ha mantenido una producción regular e importante dentro del contexto español, pese a constituir un criadero de los habitualmente clasificados como "marginales" por su escasa ley media. La utilización de los recursos técnicos disponibles, que ha conseguido el elevado grado de eficacia necesario para hacer rentable la explotación del yacimiento, ha estado basada en la experiencia como método y la simplificación de procesos como objetivos.[Abstract] For the last ten years the tin mine "El Cubito" , in the province of Salamanca, has kept a regular and important production, within the Spanish context, in spite of to belong to mineral deposits classified as "marginal" because of their short grade. The use of the available technical means, which has made possible the high degree of efficacy needed to make profitable the exploitation, has been based on the experience as method and on a simplification of processes as objetives

El yacimiento detritico-estannifero de "El cubito" (Salamanca)

[Resumen] En este trabajo se describen los caracteres geológi!cos de la mina «El Cubito» (Grupo Minero Las Españas, Salamanca.). A continuación se hace un estudio granulométrico, mineralógico y mineralotécnico del único yacimiento detrítico de estaño conocido en los sedimentos terciarios de la Cuenca del Duero, deduciéndose y discutiéndose sus condiciones metalogénicas[Abstract] The geological characteristics of the Cubito Mine (Mining Group « Las Españas», Salamanca) are described in this papero To continue a granulometric, mineraloglcal and mineralotechnical study is done of the only detritic deposit of tin known in the tertiary terrains of the Duero Basin making deductions and discussing its metallogenic condition

Distribución de elementos menores y trazas en casiteritas de distintos tipos de yacimientos españoles

[Resumen] En este trabajo se presenta, por primera vez, la composición química de muestras de casi teri tas pertenecientes a distintos tipos de yacimientos españoles, local izados a lo largo del Macizo Hespérico. Se establecen correlaciones entre los caracteres geoquímicos y genéticos, así como, entre el hábito y el color con la tipología del yacimiento: Bipirámides de tonalidades oscuras, junto con una escasa ó nula maclación, son típicas de los depósitos de diseminación y pegmatíticos. Prismas apuntados en pirámides, con una extensa gama de color y abundante maclación I son característicos de yacimientos filonianos.[Abstract] This study presents the chemical composi tion of cassi teri tes samples from different kinds of Spanish deposi ts, for first time. The correlations between geochemical and genetic characteristics are presented, and also, between habi t and colour wi th the type of deposit: Bipyramids of dark tonali ties wi th a li ttle or null twining are characteristic of dissemination and pegmati tic deposits. Pointed prims in pyramid wi th a wide range of colours and abundant twining are characteristic of lode deposit

Crustal processes sustain Arctic abiotic gas hydrate and fluid flow systems

The Svyatogor Ridge and surroundings, located on the sediment-covered western flank of the Northern Knipovich Ridge, host extensive gas hydrate and related fluid flow systems. The fluid flow system here manifests in the upper sedimentary sequence as gas hydrates and free gas, indicated by bottom simulating reflections (BSRs) and amplitude anomalies. Using 2D seismic lines and bathymetric data, we map tectonic features such as faults, crustal highs, and indicators of fluid flow processes. Results indicate a strong correlation between crustal faults, crustal highs and fluid accumulations in the overlying sediments, as well as an increase in geothermal gradient over crustal faults. We conclude here that gas generated during the serpentinization of exhumed mantle rocks drive the extensive occurrence of gas hydrate and fluid flow systems in the region and transform faults act as an additional major pathway for fluid circulation

Dispersal of aphids, whiteflies and their natural enemies under photoselective nets

Integrated Pest Management of insects includes several control tactics, such as the use of photoselective nets, which may reduce the flight activity of insects. Limiting the dispersal of pests such as aphids and whiteflies is important because of their major role as vectors of plant viruses, while a minor impact on natural enemies is desired. In this study, we examined for the first time the dispersal ability of three vector species, Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae), Macrosiphum euphorbiae (Thomas) (Hemiptera: Aphididae) and Myzus persicae (Sulzer) (Hemiptera: Aphididae), in cages covered with photoselective nets. Contrary to the results obtained with aphids, the ability of the whitefly B. tabaci, to reach the target plant was reduced by photoselective nets. In a second set of experiments, the impact of UV-absorbing nets on the visual cues of two important predator species, Orius laevigatus (Fieber) (Hemiptera: Anthocoridae) and Amblyseius swirskii Athias-Henriot (Acari: Phytoseiidae), was evaluated. The anthocorid was caught in higher numbers in traps placed under regular nets, whereas the mites preferably chose environments in which the UV radiation was attenuated. We have observed a wide range of effects that impedes generalization, although photoselective nets have a positive effect on pest management of whiteflies and aphids under protected environments

Concept of finite limit of a function at a point: meanings and specific terms

In this paper, we present some results of an exploratory study performed with students aged 16-17. We investigate the different uses that these students make of terms such as ‘to approach’, ‘to tend’, ‘to reach’, ‘to exceed’ and ‘limit’ that describe the basic notions related to the concept of the finite limit of a function at a point. We use the interpretive framework of conceptual analysis to infer the meanings that students associate with these specific terms in connection with the effective use of terms in their answers.This study was performed with aid and financing from Fellowship FPU AP2010-0906 (MEC-FEDER), Projects EDU2009-11337 and EDU2012-33030 of the National Plan for R&D&R (MICIN), Subprogram EDUC and Group FQM-193 of the 3rd Andalusian Research Plan (PAIDI).This chapter is derived in part from an article published in International Journal of Mathematical Education in Science and Technology 05 Jul 2013, available online: http://www.tandfonline.com/10.1080/0020739X.2013.80588

AngularGrad: A New Optimization Technique for Angular Convergence of Convolutional Neural Networks

Convolutional neural networks (CNNs) are trained using stochastic gradient descent (SGD)-based optimizers. Recently, the adaptive moment estimation (Adam) optimizer has become very popular due to its adaptive momentum, which tackles the dying gradient problem of SGD. Nevertheless, existing optimizers are still unable to exploit the optimization curvature information efficiently. This paper proposes a new AngularGrad optimizer that considers the behavior of the direction/angle of consecutive gradients. This is the first attempt in the literature to exploit the gradient angular information apart from its magnitude. The proposed AngularGrad generates a score to control the step size based on the gradient angular information of previous iterations. Thus, the optimization steps become smoother as a more accurate step size of immediate past gradients is captured through the angular information. Two variants of AngularGrad are developed based on the use of Tangent or Cosine functions for computing the gradient angular information. Theoretically, AngularGrad exhibits the same regret bound as Adam for convergence purposes. Nevertheless, extensive experiments conducted on benchmark data sets against state-of-the-art methods reveal a superior performance of AngularGrad. The source code will be made publicly available at: https://github.com/mhaut/AngularGrad