Solar radiation numerical models need the implementation of an accurate method for determining cast shadows on the terrain or on solar collectors. The aim of this work is the development of a new methodology to detect the shadows on a particular terrain. The paper addresses the detection of self and cast shadows produced by the orography as well as those caused by clouds. The paper presents important enhancements on the methodology proposed by the authors in previous works, to detect the shadows caused by the orography. The domain is the terrain surface discretised using an adaptive mesh of triangles. A triangle of terrain will be under cast shadows when, looking at the mesh from the Sun, you can find another triangle that covers all or partially the first one. For each time step, all the triangles should be checked to see if there are cast or self shadows on it. The computational cost of this procedure eventually resulted unaffordable when dealing with complex topography such as that in Canary Islands thus, a new methodology was developed. This one includes a filtering system to identify which triangles are those likely to be shadowed. If there are no self shadowed triangles, the entire mesh will be illuminated and there will not be any shadows. Only triangles that have their backs towards the Sun will be able to cast shadows on other triangles. Detection of shadows generated by clouds is achieved by a shadow algorithm using satellite images. In this paper, Landsat 8 images have been used. The code was done in python programming language. Finally, the outputs of both approaches, shadows generated by the topography and generated by clouds, can be combined in one map. The whole problem has been tested in Gran Canaria and Tenerife Island (Canary Islands-Spain), and in the Tatra Mountains (Poland and Slovakia).

We describe a semi-analytical method to calculate the total radiance received form a black body, between two frequencies. As has been done before, the method takes advantage of the fact that the solution simplifies with the use of polylogarithm functions. We then use it to study the amount of radiation from the sun received by bodies at Earths surface.

Titanium possesses an excellent corrosion resistance in biological environments because the titanium dioxide formed on its surface is extremely stable. When aluminium and vanadium are added to titanium in small quantities, the alloy achieves considerably higher tensile properties than of pure titanium and this alloy is used in high stress-bearing situations. But these metals may also influence the chemostatic mechanisms that are involved in the attraction of biocells. V presence can be associated with potential cytotoxic effects and adverse tissue reactions. The alloys with aluminium and iron or with aluminium and niobium occur to be more suitable for implant applications: it possesses similar corrosion resistance and mechanical properties to those of titanium-aluminium-vanadium alloy; moreover, these alloys have no toxicity.In this paper, pure Ti, Ti-6Al-7Nb and Ti-6Al-4Fe were studied. The implant materials were prepared by chemical treatment consisting in immersion in 10M aqueous NaOH solution at 60º C for 24 hours. After the attack, were washed with distilled water and dried at 40°C during 24 hours.Data about mechanical behaviour are presented. The mechanical behaviour was determined using optical metallography (Figure 1), tensile strength ( Figure 2) and Vickers microhardness.For the electrochemical measurements a conventional three-electrode cell with a Pt grid as counter electrode and saturated calomel electrod (SCE) as reference electrode was used. AC impedance data were obtained at open circuit potential using a PAR 263 A potentiostat connected with a PAR 5210 lock-in amplifier. The amplitude of the AC potential was 10 mV and single sine wave measurements at frequencies between 10 -1 and 10 5 Hz were performed for each sample. The spectra were interpreted using the non-linear least square fitting procedure.The ESEM and EDAX observations were carried out with an environmental scanning electron microscope Fei XL30 ESEM with LaB6-cathode attached with an energy-dispersive electron probe X-ray analyzer (EDAX Sapphire) For the cross section of passive layer, the sample was sputter-coated with gold for analysis. After 3 days of immersion in simulated body fluid the nucleation of the bone growth was observed on the implant surface (Figure 3).It resulted that the tested oxide films presented passivation tendency and a very good stability and no form of local corrosion was detected. The electrochemical behaviour of these films is described by an equivalent circuit with two time constants. The mechanical data confirm the presence of an outer porous passive layer and an inner compact and protective passive layer. EIS confirms the mechanical results. The thicknesses of these layers were measured. SEM photographs of the surface and EDX profiles for the samples illustrate the appearance of a microporous layer made up of an alkaline titanate hydrogel. It can be observed that the Na concentration is bigger just under the surface and starts to decrease as is analysed deeper in the passive layer. The apatite-forming abili...