A rapidly changing market leads to software systems with highly volatile requirements. In many cases, new demands in software can often be met by extending the functionality of systems already in operation. By modularizing volatile requirements that can be altered at the client’s initiative or according to market demands, we can build a stepping-stone for management of requirements change. The volatility must be managed in a way that reduces the time and costs associated with updating a system to meet the new requirements. In this chapter, we present an approach for handling volatile concerns during early life cycle software modeling. The key insight is that techniques for aspect-oriented software development can be applied to modularize volatility and to weave volatile concerns into the base software artifacts.

Li2O-BaO-Al2O3-La2O 3-P2O5 glasses optically activated with rare earth ions with the 4f5, and 4f8 electronic configuration (Sm3+ and Tb3+, respectively) were analyzed by Raman spectroscopy, absorption, excitation photoluminescence, decay curves and temperature dependent photoluminescence. The spectroscopic characteristics of the as-prepared and heat treated samples at temperatures below and above T g were studied as well as their room temperature photometric properties under ultraviolet excitation. All the doped glasses exhibit typical signatures of the lanthanides in their trivalent charge state. For the samarium doped glass heat treated at 250 C (<Tg) the Sm2+ luminescence was also observed. The analysis of the luminescence efficiency was performed in the interval range of 14 K to room temperature, where the integrated intensity of the luminescence was found to decrease for the Sm 3+ and Tb3+ ions in the studied temperature range. Luminescence decay curves were found to be non-exponential for the 4G5/2 → 6H7/2 and 5D3 → 7F4 transitions of the Sm3+ and Tb3+ ions, respectively. The results strongly suggest the occurrence of energy transfer processes through cross relaxation phenomena, mediated by dipole-dipole interaction in all the studied samples. The decay of the 5D4 → 7F5 emission of the Tb3+ ions was found to be single exponential with a time constant of ∼3.1 ms. Based on the spectroscopic characteristics, models for recombination processes are proposed. The room temperature luminance photometric properties with ultraviolet excitation show that the samarium doped glasses have much lower luminance intensity (around 0.3 Cd/m2) when compared with the 6-7 Cd/m2 observed for the terbium doped ones. © 2013 Elsevier B.V. All rights reserved.

Hydroxyapatite [Hap; Ca10(PO4)6(OH)2) and b-tricalcium phosphate [b-TCP; Ca3(PO4)2] are biocompatible calcium phosphates used in skeletal surgery. The natural HAp is one of the main components of bone and, as a synthetic material, has been widely used for bone replacement presenting good bioactivity. Nevertheless synthetic HAp presents a slow in vivo degradation rate which is disadvantageous for bone’s reparative process. b-TCP has also good osteogenic characteristics presenting the ability to form strong bonds with the bone however, its degradation rate is too fast [1]. Therefore, a composite combining these two ceramics is valuable as it exhibits a suitable degradation rate. Because of the piezoelectric properties of bone it is known that electrical polarization of calcium phosphates can enhance the bioactivity and biointegration of implants [2]. Previous studies have already showed that HAp/b-TCP ceramics can be electrically polarized and that electrical polarization enhances osteogenesis in the early stage of the implantation process. However further studies are required to understand, optimize and improve the polarization technique [1]. In this work a commercial biphasic ceramic powders were pressed in a mold at 200 MPa to produce disc shaped samples. Afterwards, the samples were sintered at temperatures from 950ºC to 1150ºC and the influence of the heat treatment in the electrical polarization and subsequent bioactivity was investigated. The samples were polarized under a high DC electric field at relatively lower temperature (200oC) compared to previous studies and the stability of polarization was tested using TSDC (thermally depolarization currents) measurements. It was studied the influence of the water, initially present in the material, in the total charge deposited during polarization, its stability and its relation with heat treatment after pressing. The influence of the addition of b-TCP on sample’s stored charge was also evaluated. Finally bioactivity tests in a simulated body fluid solution were made taking into account the signal of the charge in each surface of the disc samples so that the results could be compared to previous ones.

Marinobacter hydrocarbonoclasticus is a marine bacterium widespread in the Mediterranean sea and Atlantic Ocean, and growing at temperate temperatures. This bacterium can perform complete denitrification, reducing nitrate to molecular nitrogen under anaerobic conditions. Here the nitrite concentration, pH and nitrous oxide reductase activity was monitored during bacterial growth, showing that this bacterium can also perform complete denitrification under low oxygen tension, using lactate as carbon source, in the presence of nitrate as alternative electron acceptor. Nitrous oxide reductase activity was observed after 7 h of growth under low oxygen tensions, and is maintained constant after 48h. Nitrite concentration reaches its maximum at mid-exponential phase and in the stationary phase, at lower oxygen tensions is almost non-existent.

A transient heat transfer model was developed to numerically predict the thermal behaviour of the external walls of a room under realistic outdoor conditions. The excitation is not simply sinusoidal even though it is considered to have daily periodicity. The numerical model is based on the finite difference method and handles one-dimensional heat conduction through multilayered walls. The boundary condition at the outer surface of the wall is described with the sol-air temperature concept. The temperatures of indoor air and of other internal surfaces in the room are assumed to be equal and constant. The numerical results were used to calculate values of the decrement factor and time lag of several walls. The calculation followed two methods found in literature, in which these parameters are assumed constant, distinguished by the temperature evolution used: the sol-air or the wall's outer surface. Additionally, the inner surface temperature is used in both methods. The walls investigated range from low to high mass construction, face towards various directions and have light or dark coloured sunlit outer surfaces. The heat fluxes at the inner surface of the walls predicted by numerical modelling and estimated by the simplified methods are compared in detail to conclude on the validity of these simplified methods. As a by-product it is also possible to conclude on the dependence of the decrement factor and of the time lag on the outer surface colour and on the orientation of different types of walls. The results show that both simplified methods have poor accuracy in a significant number of cases. Also, it was found that the wall's azimuth significantly affects the time lag.© 2013 Published by Elsevier B.V.

The Cooling Load Temperature Difference (CLTD) values available in the literature for using the simplified CLTD method only apply to rooms under constant indoor air temperature. Due to this limitation, the present paper extends the application of this simplified approach to cooling and heating loads estimation of rooms with daily and weekend setback and setup thermostats, and introduces the term thermal load temperature difference (TLTD). To generate the values of TLTD, a transient heat transfer model, and the corresponding numerical tool, has been developed to predict the thermal behaviour of multilayered walls and flat roofs. The sol-air temperature concept is used. The internal thermal capacity of the room is assumed negligible. The TLTD evolutions have been generated for a wall and a roof, of high mass construction, with setback and setup thermostats in winter and summer scenarios. The periods in which the room is unoccupied have been taken in due account. The TLTD evolutions allowed the estimation of: the energy transferred at the inner surface and the maximum thermal load. Among the cases studied, the relative difference found in the energy transferred through the sunlit envelope, roof or wall under summer conditions, is about 20% when the temperature control strategy is changed from A to B. © 2012 Elsevier Ltd. All rights reserved.

In this work Laponite was combined with a modified abundant natural polymer, (caboxymethyl cellulose), acrylic sodium salt polymer and lithium perchlorate aiming to produce inexpensive and sustainable nanocomposite electrolytes for functional electrochemical devices. Optical, electrochemical, structural, morphological and rheological characterization was performed in order to evaluate their properties and potential advantages as electrolyte. It was verified that the addition of Laponite led to an ionic conductivity at room temperature (25 C) in the range of 6 to 9 × 10- 5 Scm - 1 this value being then determined by the composition of the nanocomposite. These electrolytes were applied to electrochromic devices using evaporated nickel oxide thin film as the electrochromic layer. The devices exhibited a significant transmittance modulation that exceeds 45 % at 600 nm. © 2013 Elsevier B.V.