This paper deals with combustion of premixed and diffusion methane flames. Temperature and emission measurements of premixed and diffusion methane flames have been carried out in the present study. A new combustion system including burners and combustor has been designed and manufactured in order to determine the temperature and emission values of methane flames throughout the combustor. This combustion system includes burners, combustor, gas and air lines, regulators, manometers, flowmeters and so on. Premixed and diffusion burners with a capacity of 10 kW have been used so as to burn the methane during the experiments. Temperatures have been determined by using thermocouples throughout the combustor. Emission values have also been measured via a flue gas analyzer throughout the combustor. The results show that the maximum flame temperatures have been measured as of 1230°C under the premixed flame conditions and as of 1193°C under the diffusion flame conditions. When it comes to emission measurements, it may be said that the maximum NOX and CO2 emission levels form in the flame region while minimum CO formations emerge in the same region under the premixed combustion conditions due to the complete combustion conditions in the premixed burner. Therefore, it can be concluded that complete combustion has been nearly achieved by the premixed methane burner.

Tensegrity structures are an innovative class of lightweight structures, which have gained the interest of researchers in many different fields, including but not limited to engineering. In particular, such interest is due to their aesthetic value, their large stiffness-to-mass ratio, the possible deployability, together to their reliability and controllability. Tensegrity structures, made of struts in compression and cables necessarily in tension, are innovative structures by itself: they are similar only in appearance to conventional pin-joint structures (trusses), and their mechanical behavior is strongly related to initial feasible self-stress states induced in absence of external loads. In particular, from a kinematical point of view, these self-stress states avoid the activation of possible infinitesimal mechanisms. In this paper, we study an innovative class of tensegrity beam-like grids, obtained by a suitable assembly of three elementary V-Expander tensegrity cells along a longitudinal axis (named x-axis) in the three-dimensional space. In particular, by means of a numerical study, we analyze the feasible self-stress states for seven tensegrity beam-like grids, with increasing degree of complexity, made by an arrangement of V-Expander elementary cells. Moreover, we analyze the influence on the feasible self-stress states of the addition of elements starting from the simplest V-Expander tensegrity configuration.

We present a theoretical and experimental approach for the characterization of the damage induced anisotropy superimposed to the constitutive anisotropy of fiber-reinforced composite materials. The theoretical model here employed has been developed in the framework of the Continuum Damage Mechanics theory and allows for determining a tensorial damage measure based on the change of the elastic moduli of the composite material. Moreover, the model is general since it is applicable independently of the fibers reinforcement nature, of the presence of cracks, interlaminar voids and delamination, of the geometry of this cracks, and from of failure mechanisms of the composite materials. We perform damage experiments by using an innovative goniometric device designed and built at our laboratory (Laboratorio “M. Salvati”), and aimed at the mechanical characterization of materials. In particular, by rotating the sample into a water tank, we measure the ultrasonic “natural” velocities of the undamaged composite material along suitable propagation directions. This allows us for classifying the degree of symmetry of the material and for determining the elastic constants, also in highly anisotropic materials. Then we measure the ultrasonic velocities of the artificially damaged composite and we determine again the elastic moduli. The comparison between the elastic moduli of the damaged and the undamaged composite allows us for the characterization of the above cited anisotropic tensorial damage measure.

The Response Spectrum Analysis of the structures is based on the allowable ductility considered for that structure. In the case of multi-degree-of-freedom buildings, the required ductility cannot be the same with the allowable ductility; furthermore, the required ductility values are different for different storey. In the case of first soft/weak storey building, the required ductility of this storey is much higher compared to allowable ductility and impossible to achieve. Nowadays there are many cases of existing reinforced concrete structures with the possibility of soft/weak storey. Even new structures are required to have open space at ground floor level as the owners want them for shops or garages usage. This paper analysis the influence of base isolation to the required storey ductility of weak storey buildings. A five storey shear frame type structure is considered as the model. The elastic and elasto-plastic modeling of the structural elements and bilinear modeling of rubber isolators are used. Linear Response Spectrum analysis and Nonlinear Time History analysis are performed in order to determine the required storey ductility for the existing and new soft/weak storey buildings using the SAP2000 computer program. The analysis results show the reduction of the required storey ductility due to the application of base isolation not only in new structures, but in existing structures too. This means that the base isolation technique is a good alternative to be applied in buildings with first soft/weak storey structure.

Geopolymer is a new development in the world of concrete in which cement is totally replace by pozzolanic material like fly ash and activated by highly alkaline solutions to act as a binder in the concrete mix. Experimental investigation has been carried out to find the effect of fineness of fly ash and alkaline solutions ratio on the mechanical properties of fly ash based geopolymer concrete. Geopolymer concrete is produced by activating fly ash with a highly alkaline solution of sodium silicate containing 16.32% Na2O, 32.75% SiO2 and 50.93% H2O and sodium hydroxide solution having 13 molar concentrations is maintained constant throughout the study. Compressive strength, split-tensile strength and flexural strength are obtained using three samples of fly ash with fineness of 364, 442 and 610 m2/kg. Alkaline ratio (i.e., Na2SiO3/NaOH ratio) of 1, 1.5, 2, 2.5, 3 and solution to fly ash ratio of 0.35 is considered. The specimens are cured in an oven for 110 oC for 7 hrs and tested after 7 and 28 days rest period. It is observed that the fineness of fly ash in terms of specific surface area (m2/kg) increases the strength of geopolymer concrete and optimize at alkaline solution ratio at 1.5.