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In the last years, even more attention was paid to the alternative fuels that allow both reducing the fossil fuel consumption and the pollutant emissions. Gaseous fuels like methane and hydrogen are the most interesting in terms of engine application. This paper reports a comparison between methane and different methane/hydrogen mixtures in a single-cylinder Port Fuel/Direct Injection spark ignition (PFI/DI SI) engine operating under steady state conditions. It is representative of the gasoline engine for automotive application. Engine performance and exhaust emissions were evaluated. Moreover, 2D-digital cycle resolved imaging was performed with high spatial and temporal resolution in the combustion chamber. In particular, it allows characterizing the combustion by means of the flame propagation in terms of mean radius and velocity. Moreover, the interaction of turbulence with the local flame was evaluated. For both the engine configurations, it was observed that the addition of hydrogen results in a more efficient combustion, even though the engine configuration plays an important role. In PFI mode, the lower density of hydrogen causes a lower energy input. In DI mode, instead, the larger hydrogen diffusivity counteracts the charge stratification especially for larger hydrogen content. © 2016 Elsevier Ltd. All

Using 40-year experiment data from a mono-modal rainfall area of northern Togo, we analyzed soil fertility dynamics when 2 and 3-year fallows were alternated with 3-year rotation of groundnut, cotton and sorghum. The control treatment consisted to continuous cultivate the soil in a rotation of groundnut/cotton/sorghum without fallow periods. For each rotation, two fertilisation rates were applied: no fertilisation and mineral fertiliser application during the cropping and/or the fallow periods. Yields of unfertilised crops, which averaged 1 t ha-1 during the first years of cultivation, were often nil in the long-term. In the long-term, yields of fertilised cotton and sorghum decreased by 32 and 50 %, respectively compared to the average of 2.4 and 1.6 t ha-1 obtained during the first decade of cultivation. The long-term decline in crop productivity was mitigated when fallow periods were alternated with cropping periods, and consequently there was partial compensation in terms of production for the unproductive fallowed plots. Long-term yields of fertilised cotton and sorghum in the periodically fallowed plots were 40 and 50 % higher than those in continuously cropped plots, respectively; they were 90 and 60 % higher than those in continuously cropped plots without fertilisation. Like for crop productivity, soil C, N and exchangeable Ca and Mg decreased less in periodically fallowed plots than in continuously cropped plots. The limited soil C decline when fallows were alternated with crops appears to be the consequence of no-tillage period rather than the effect of the highest C inputs to the soil.

Responses to recent climatic changes in the sediment of subarctic Lake Saanajärvi in northwestern Finnish Lapland are studied by comparison of various biological and sedimentological proxies with the 200-year long climate record, specifically reconstructed for the site using a data-set of European-wide meteorological data. The multi-proxy evidence of simultaneously changing diatom, Cladocera, and chrysophyte assemblages along with the increased rates of organic matter accumulation and pigment concentrations suggest that the lake has undergone a distinct typological change starting from the turn of the 20th century. This change, indicating an increase in lake productivity, parallels a pronounced rise in the meteorologically reconstructed mean annual and summer temperatures in the region between ca. 1850 and 1930's. We postulate that, during the Little Ice Age, the lake was not, or was only weakly, thermally stratified during summer, whereas the subsequent increase in air and hence epilimnetic water temperatures resulted in the development of the present summer stratification. The increased thermal stability of the lake created more suitable conditions for the growth of phyto- and zooplankton and changed the overall primary production from benthos to plankton. Mineral magnetic and carbonaceous particle records suggest long-distance pollution, particularly since the 1920's, yet the observed changes in lake biota and productivity can hardly be explained by this very minor background pollution; the 20th century species configurations are typical of neutral waters and do not indicate any response to pollution.

Chemical looping combustion allows a simple separation of CO2 during the combustion of fossil fuels, thanks to the use of regenerable oxygen carriers. In this work, novel materials containing manganese and iron/manganese oxides have been developed via geopolymerization, and characterized in thermogravimetric apparatus and fixed bed reactor. The materials demonstrated suitable characteristics for chemical looping combustion (CLC). The tests conducted in the temperature range 800-900 °C revealed the good performance of the developed oxygen carriers, which also exhibited the ability to release O2 in inert conditions. Efficiencies in CO conversion up to 99% were achieved, as well as some synergies between Fe and Mn oxides gave a beneficial effect toward the oxygen yield. X-ray diffraction analyses of the samples confirmed the effective reduction/oxidation behavior of the materials, as well as the morphological characterization did not reveal dramatic changes of the internal microstructure up to 900 °C

The most widely used process for hydrogen production is steam methane reforming. It can be carried out using a membrane reactor in which simultaneous hydrogen production and purification occur. Mathematical modeling of these reactors plays a key role in the selection of the design and operating parameters that yield high performance for the reactor. This review study discusses, synthesizes, and compares different mathematical modeling studies on the packed bed membrane reactors for hydrogen production from methane found in the literature. Different approaches used in these modeling studies for the hydrogen permeation steps, reaction kinetic expressions, phases involved (pseudo-homogeneous and heterogeneous), and spatial dimensions (one, two, and three dimensional) are given.

The reversible dissociation/carbonation of metal carbonates, performed in fluidized bed reactors, is one of the most promising technological solution for thermochemical energy storage (TCES) in concentrating solar power plants (CSP). In this framework, the SrCO3/SrO system is receiving increasing interest due to its high energy density (4 GJ/m3) and working temperatures (up to 1200 ?C). As the more investigated CaCO3/CaO couple, also SrO undergoes a dramatic drop of reactivity over multiple carbonation/calcina- tion cycles due to sintering. Even though the potentiality of this system has already been proved by thermo-gravimetric analyses, its actual reaction performances in a fluidized bed are strongly dependent on the gas-solid contact efficiency and heat/mass transfer between the gaseous and solid phase. In this work, the cyclic carbonation/calcination of the SrO/SrCO3 system for TCES-CSP has been investigated by thermo-gravimetric analysis and, for the first time, in a lab-scale fluidized bed rig, thus providing useful applicative insights. A new Al2O3-stabilized composite has been synthesized, i.e. Al2O3 has been added to SrO/SrCO3 system as both sintering inhibitor and flow conditioner. In particular, composite materials with different Al2O3/SrO composition have been synthesized to investigate the ef- fect of the inhibitor amount on both the fluidizability and energy storage performances.

Intention of this work is to investigate the opportunity and feasibility of energy efficient networking in Home and Building automation protocols. Wired HBAS have traditionally devoted a relatively little attention to this point, especially if compared to wireless networks. This paper will try to address the issue by evaluating the introduction of power state switching in a real scenario and proposing the concept of functional and spatial adjacency among packets.

Il volume contiene gli abstract dei lavori accettati per i contributi orali e i poster presentati a HYPOTHESIS XII