New thermosets obtained by cationic copolymerization of DGEBA with γ‐caprolactone with improvement in the shrinkage. II. Time–temperature–transformation (TTT) cure diagram

Mixtures of diglycidylether of bisphenol A (DGEBA) with different proportions of γ‐caprolactone (γ‐CL) were cured with ytterbium triflate as initiator. The curing was studied with differential scanning calorimetry (DSC) and thermo mechanical analysis (TMA). The results are presented in the form of a time–temperature–transformation diagram. The kinetic analysis was performed by means of the isoconversional integral procedure and the kinetic model was also determined using the Coats–Redfern method. Gelation was determined by means of combined experiences of DSC and TMA. The relationship between the glass transition temperature (T_g) and the degree of conversion α was determined by DSC. Using the isoconversional lines and the T_g‐α relationship, the vitrificacion curve was obtained. The methodology developed makes it possible to obtain the TTT diagram using only no‐isothermal experiments with equivalent results to those using classical isothermal procedures. The addition of γ‐CL accelerates the curing and reduces the shrinkage after gelation and consequently the internal stresses in the material. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

A new methodology towards determining building performance under modified outdoor conditions

Great efforts have been made to establish the influence of the urban climate upon the energy consumption of buildings. While many scientific articles present measured data of increased energy consumption due to building surroundings, this paper aims to present a straightforward methodology for the assessment of building performance under modified outdoor conditions. Designers and urban planners should benefit from the results of this paper in their evaluation of proposals to decrease building energy consumption. A number of examples are discussed in order to illustrate the methodology outlined.     

Climatic zoning and its application to Spanish building energy performance regulations

The main requirements of European Directive 2002/91/EC on the energy performance of buildings (EPBD) are the application of minimum energy performance requirements for new buildings and certification of the energy performance of buildings. Its transposition into the national law of member states of the European Union has signified the appearance of new and more onerous requirements in terms of construction quality from the point of view of energy performance, and in terms of the procedure for certification of the energy performance of buildings. In both cases, the levels required tend to be based on climatic conditions, fundamentally in countries such as Spain, where the climatic variability is very pronounced. This paper presents a methodology developed for the climatic zoning of the localities not included in the above-mentioned regulations in order to facilitate their application. By way of example, the method is shown which was used to generate the climatic files and carry out the subsequent climatic zoning of all the municipalities of the region of Andalusia in southern Spain.     

Cement content determination through selective stain in hardened concrete

A cement quantification method has been developed in Ø 15 × 30 cm concrete specimens applying selective stain. A tannic acid–tartaric acid solution was used to stain the cement paste.This paper explains the procedure to determine the quantity of cement in the samples: the reagents utilised for the stain, preparation, cutting and stain of the specimens, the capture and treatment of images of the stained samples, and the preparation of the calibration curves.Next, we assess the accuracy of this method and include the resolution of a practical case in which a comparison is drawn between the values obtained through the application of this method and those obtained using a ‘reference’ method.     

Revision of the Trombe wall calculation method proposed by UNE-EN ISO 13790

The European and International Standard UNE-EN ISO 13790 presents a set of calculation methods for the evaluation and design of energy and thermal performance of buildings. These methods have diverse range of details for calculating the energy use of heating and cooling in different building zones, as well as for calculating the heat transfer and solar heat gains of special elements, such as ventilated solar walls (Trombe walls). In this article, the authors have revised the aforementioned document in order to check the proposed mathematical models and their implementation within Mediterranean climates. This assessment pinpoints the existence of some errors in the equations provided in EN ISO 13790 under steady state conditions. Concurrently, the corrected equations are shown and new correlations are proposed for the ratios δ and ω which are more suitable for Mediterranean climates.     

Solar radiation calculation methodology for building exterior surfaces

The present article shows a new methodology of calculation of the direct, diffuse and reflected incident solar radiation, in all type of surfaces, either in open urban environments or inside buildings. This methodology is applicable in problems related to solar access (space heating in buildings, shadowing of open spaces), solar gains (space cooling in buildings), and daylighting. Solar radiation is the most important contribution to the surface and volumetric energy balance during the daytime. Particularly, solar radiation is the main contributor to heat gains in buildings, especially in residential buildings, where internal gains are very low. Utilization of daylight in buildings may result in significant savings in electricity consumption for lighting while creating a higher quality indoor environment. Additional energy savings may also be realized during cooling season, when reduction of internal heat gains due to electric lighting results in a corresponding reduction of cooling energy consumption.The analysis of the existing calculation methods and proposed in the scientific bibliography for the calculation of the solar radiation in problems of solar access in winter, solar gains in summer, and daylighting, takes us to the necessity of outlining a new and complete methodology. This new methodology is applicable to all these problems with a great accuracy and calculation speed.     

A Programmable Imager for Very High Speed Cellular Signal Processing

In this paper a programmable imager with averaging will be described which is intended for averaging of different groups or sets of pixels formed by n × n kernels, n × m kernels or independent pixels of the array. This imager is a 64 × 64 array which uses passive pixels that can be randomly accessed. The read-outstage includes a sole charge amplifier with programmable gain, a sample-and-hold structure and an analog buffer. This read-out structure is different from other existing imagers with variable resolution since it uses a sole charge amplifier, whereas the normal structure is an operational amplifier per column plus a global operational amplifier. This structure will be described in detail indicating the advantages and disadvantages with respect to other imagers with averaging capabilities. This programmable resolution architecture can be more appropriate, and eventually, more efficient, when implementing very high speed Cellular Neural Network (CNN) processors in a CNN chipset—a mixed-signal hardware platform for CNN-based image processing. A significant processing time reduction can be obtained when decreasing the image resolution, and therefore the amount of information to be transferred to the CNN processor. This programmable resolution can also be used for fast image recognition and ulterior windowing at full resolution in a reduced area of the image, permitting a more accurate processing of the region of interest. In addition, full resolution images can still be obtained, as in commercial imagers which are usually included in CNN chipsets.