Growth,X-ray peak broadening studies,and optical properties of Mg-doped ZnO nanoparticles

Undoped and Mg-doped ZnO nanoparticles (NPs) (Zn_1?xMg_xO, x=0.01, 0.03, and 0.05) were grown by the sol–gel method. X-ray results showed that the products were crystalline with a hexagonal wurtzite phase. Microscopy studies revealed that the undoped ZnO NPs and Zn_1?xMg_xO NPs had nearly spherical and hexagonal shapes. The size–strain plot (SSP) method was used to study the individual contributions of crystallite sizes and lattice strain on the peak broadening of the undoped and Mg-doped ZnO NPs. Some physical parameters such as strain, stress, and energy-density values were calculated for all reflection peaks of the XRD corresponding to the wurtzite hexagonal phase of ZnO in the 20–100° range from the SSP results. The effect of doping on the band-gap was also investigated by a photoluminescence (PL) spectrometer. The PL results showed that Mg²⁺ is a good dopant to control band gap of the ZnO properties.     

Palladium-catalysed amination of bromofluorans and an investigation of their thermochromic behaviour

The palladium-catalysed amination of readily accessible bromofluorans and bromobenzo[a]fluorans has been accomplished with a series of anilines and morpholine. The resulting aminofluorans generated intense black shades upon formulation in methyl stearate containing bisphenol A. The route provides an alternative approach to various amino substituted fluorans without the need of a series of individual diphenylamine intermediates.     

Influence of secondary source technologies and energy management strategies on Energy Storage System sizing for fuel cell electric vehicles

Fuel cell electric vehicles (FCEVs) have some limitation which make them less competitor to thermal ones and delay their commercialization. The most important problems as the range, the durability and the cost depend directly on the energy storage problematic issues. In this context, this work presents an optimal sizing methodology for an Energy Storage System (ESS) composed by a fuel cell and an assistant source to supply a lightweight vehicle with 700 km driving range. Firstly, a comparative study between single and hybrid source is carried out to show the benefits of hybridization according to the range in terms of weight, cost and fuel consumption. Moreover, in order to improve the hybrid source characteristics, three technologies of the secondary source are tested and evaluated to be chosen for hybridization with fuel cell system purposes. Furthermore, the influence of three Energy Management Strategies (EMSs) on ESS sizing is studied where an optimal strategy provides the most favorable dimensions of the hybrid system. Simulation results give us the best technology needed for hybridization and allow us adopting the optimal management strategy to design the hybrid source. Finally, in order to show the influence of the driving cycles on the ESS design, a comparison study using the New European Driving Cycle “NEDC” and the Assessment and Reliability of Transport Emission Models Inventory Systems (ARTEMIS) confirms that there is a slow influence of the driving cycle on the ESS sizes.     

Developing electrochemical measurements in order to assess anti-corrosive coatings more effectively

The aim of this project was to check reproducibility of results obtained using NOCS (no connection to the substrate) arrangement of the electrochemical noise method (ENM). NOCS involves taking measurements from three nominally identical areas on the coated surface. Thus, no electrical connection to substrate is required. In practice the areas are not identical and various arrangements for connection of the three cells were tried to see if the individual areas could be separated out and whether the individual resistances could be computed. Also different ways of calculating the R_n (noise resistance) and R_sn (spectral noise resistance) parameters were attempted to see which one gave the best comparison with the more standard EIS measurements. The maximum entropy method was recognized to be the most useful for comparison with EIS, as well as for graphic evaluation of results. Regarding distinguishing three areas using different connection arrangements, it was possible to identify the situation when one of the three values was different to the other two. However further experiments are needed before it will be possible to confidently assign an R_n value to each individual area.     

Free and Open Source Software versus Internet content filtering and censorship: A case study

This study critically investigates the main characteristics and features of anti-filtering packages provided by Free and Open Source Software (FOSS). For over a decade, the digital communities around the globe have used FOSS packages not only as an inexpensive way to access to information available on Internet, but also to disseminate thoughts, opinions and concerns about various socio-political and economic matters. Proxy servers and FOSS played a vital role in helping citizens in repressed countries to bypass the state imposed Internet content filtering and censorship practices. On the one hand, proxy servers act as redirectors to websites, and on the other hand, many of these servers are the main source for downloading FOSS anti-filtering software packages. These packages can provide secure web surfing via anonymous web access, data encryption, IP address masking, location concealment, browser history and cookie clean-ups but they also provide proxy software updates as well as domain name updates.The main objectives of this study are to investigate the role of FOSS packages in combating Internet content filtering and censorship and empowering citizens to effectively participate in communication discourse. By evaluating some of the well known FOSS anti-filtering packages used by Iran's digital community, this study found that despite the success of FOSS in combating filtering and state censorship, the majority of these software packages were not designed to meet the needs of Internet users. In particular, they are poorly adapted to the slow Internet connections in many developing countries such as Iran. In addition, these software packages do not meet the level of sophistication used by authorities to filter the content of the Net. Therefore, this study offers a new model that takes into account not only the existing level of the Internet infrastructure but also the growing number of Internet users demanding more effective FOSS packages for faster access to uncensored information while maintaining anonymity.     

New quadratic solid–shell elements and their evaluation on linear benchmark problems

This paper is concerned with the development of a new family of solid–shell finite elements. This concept of solid–shell elements is shown to have a number of attractive computational properties as compared to conventional three-dimensional elements. More specifically, two new solid–shell elements are formulated in this work (a fifteen-node and a twenty-node element) on the basis of a purely three-dimensional approach. The performance of these elements is shown through the analysis of various structural problems. Note that one of their main advantages is to allow complex structural shapes to be simulated without classical problems of connecting zones meshed with different element types. These solid–shell elements have a special direction denoted as the “thickness”, along which a set of integration points are located. Reduced integration is also used to prevent some locking phenomena and to increase computational efficiency. Focus will be placed here on linear benchmark problems, where it is shown that these solid–shell elements perform much better than their counterparts, conventional solid elements.