2,485 research outputs found
Cluster Approximation for the Farey Fraction Spin Chain
We consider the Farey fraction spin chain in an external field . Utilising
ideas from dynamical systems, the free energy of the model is derived by means
of an effective cluster energy approximation. This approximation is valid for
divergent cluster sizes, and hence appropriate for the discussion of the
magnetizing transition. We calculate the phase boundaries and the scaling of
the free energy. At we reproduce the rigorously known asymptotic
temperature dependence of the free energy. For , our results are
largely consistent with those found previously using mean field theory and
renormalization group arguments.Comment: 17 pages, 3 figure
Modelling fire-fighter responses to exercise and asymmetric infrared radiation using a dynamic multi-mode model of human physiology and results from the Sweating Agile thermal Manikin
Abstract : In this study, predicted dynamic physiological responses are compared with wear trials results for firefighter suits: impermeable (A), semi-permeable (B) and permeable (C), and underwear. Wear trials consisted of three rest phases and two moderate work phases, with a frontal infrared (IR) radiation exposure of 500W/m2 for the last 15min of each work phase. Simulations were performed by detailed modelling of the experimental boundary conditions, including the inhomogeneous IR radiation combined with clothing properties for still and walking conditions measured using the Sweating Agile thermal Manikin. Accounting for the effect of sweat gland activity suppression with increased skin wettedness, the predicted total moisture loss was insignificantly different (P<0.05) from the wear trial value for suits B and C but was 37% too high for suit A. Predicted evolution of core, mean skin and local skin temperatures agreed well with the wear trial results for all clothing. Root mean square deviations ranged from 0.11°C to 0.26°C for core temperatures and from 0.28°C to 0.38°C for mean skin temperatures, which where typically lower than the experimental error. Transient thermodynamic processes occurring within suit A may account for the delayed/reduced fall in core temperature following exercis
Estimation of carbon storage of forest biomass for voluntary carbon markets: preliminary results
Estimating the carbon storage of forests is essential to support climate change mitigation and promote the transition into a low-carbon emission economy. To achieve this goal, voluntary carbon markets (VCMs) are essential. VCMs are promoted by a spontaneous demand, not imposed by binding targets, as the regulated ones. In Italy, only in Veneto and Piedmont Regions (Northern Italy), VCMs through forestry activities were carried out. Valle Camonica District (Northern Italy, Lombardy Region) is ready for a local VCM, but carbon storage of its forests was never estimated. The aim of this work was to estimate the total carbon storage (TCS; t C ha 121) of forest biomass of Valle Camonica District, at the stand level, taking into account: (1) aboveground biomass, (2) belowground biomass, (3) deadwood, and (4) litter. We developed a user-friendly model, based on site-specifc primary (measured) data, and we applied it to a dataset of 2019 stands extracted from 45 Forest Management Plans. Preliminary results showed that, in 2016, the TCS achieved 76.02 t C ha 121. The aboveground biomass was the most relevant carbon pool (48.86 t C ha 121; 64.27% of TCS). From 2017 to 2029, through multifunctional forest management, the TCS could increase of 2.48 t C ha 121 (+3.26%). In the same period, assuming to convert coppices stands to high forests, an additional TCS of 0.78 t C ha 121 (equal to 2.85 t CO2 ha 121) in the aboveground biomass could be achieved without increasing forest areas. The additional carbon could be certifed and exchanged on a VCM, contributing to climate change mitigation at a local level
High Accuracy Site-Specific Secondary Data for Mechanical Field Operations to Support LCA Studies
The aim of the study was to quantify site-specific secondary data of mechanical field operations for EU barley cropping. By the model ENVIAM v2, each operation was subdivided into 13 working times and, for each of them, the amount of total consuming inputs (fuel, lubricant and AdBlue\uae) and emissions of exhaust gases into the atmosphere were calculated. The amount of partial consuming inputs (machinery mass) and emissions of heavy metals into the soil were also quantified. Three scenarios (S) were identified: S1\u2009=\u200950 ha, S2\u2009=\u2009100 ha, S3\u2009=\u2009200 ha, with the same: agronomic conditions, operations sequence, type of machines used and cropping inputs. For each scenario, two barley ideotypes were analyzed: (i) currently in use (BarNow, 2018) and (ii) future (BarPlus, 2030). BarPlus is characterized by: (i) higher grain and straw yield, Nitrogen fertilization rate and machinery Effective Field Capacity, (ii) use of TIER 5 fuel engines, (iii) lower specific minimum fuel consumption. BarNow inputs (kg\ub7ha 121) were: fuel\u2009=\u200967 \uf7 74, lubricant\u2009=\u20090.56 \uf7 0.73, mass\u2009=\u20097.9 \uf7 8.8. BarPlus inputs (kg\ub7ha 121) were: fuel\u2009=\u200955 \uf7 60, lubricant\u2009=\u20090.53 \uf7 0.69, AdBlue\uae\u2009=\u20092.8 \uf7 3.0, mass\u2009=\u20097.2 \uf7 8.0. The highest fuel and mass consumptions were in both cases related to tillage operations
Asymptotics of the Farey Fraction Spin Chain Free Energy at the Critical Point
We consider the Farey fraction spin chain in an external field . Using
ideas from dynamical systems and functional analysis, we show that the free
energy in the vicinity of the second-order phase transition is given,
exactly, by
Here is a reduced
temperature, so that the deviation from the critical point is scaled by the
Lyapunov exponent of the Gauss map, . It follows that
determines the amplitude of both the specific heat and susceptibility
singularities. To our knowledge, there is only one other microscopically
defined interacting model for which the free energy near a phase transition is
known as a function of two variables.
Our results confirm what was found previously with a cluster approximation,
and show that a clustering mechanism is in fact responsible for the transition.
However, the results disagree in part with a renormalisation group treatment
Marker based Thermal-Inertial Localization for Aerial Robots in Obscurant Filled Environments
For robotic inspection tasks in known environments fiducial markers provide a
reliable and low-cost solution for robot localization. However, detection of
such markers relies on the quality of RGB camera data, which degrades
significantly in the presence of visual obscurants such as fog and smoke. The
ability to navigate known environments in the presence of obscurants can be
critical for inspection tasks especially, in the aftermath of a disaster.
Addressing such a scenario, this work proposes a method for the design of
fiducial markers to be used with thermal cameras for the pose estimation of
aerial robots. Our low cost markers are designed to work in the long wave
infrared spectrum, which is not affected by the presence of obscurants, and can
be affixed to any object that has measurable temperature difference with
respect to its surroundings. Furthermore, the estimated pose from the fiducial
markers is fused with inertial measurements in an extended Kalman filter to
remove high frequency noise and error present in the fiducial pose estimates.
The proposed markers and the pose estimation method are experimentally
evaluated in an obscurant filled environment using an aerial robot carrying a
thermal camera.Comment: 10 pages, 5 figures, Published in International Symposium on Visual
Computing 201
On the Development of Agricultural Mechanization to Ensure a Long- Term World Food Supply
Rosana G. Moreira, Editor-in-Chief; Texas A&M UniversityThis is an Invited Paper from International Commission of Agricultural Engineering (CIGR, Commission Internationale du Genie Rural) E-Journal Volume 4 (2002): J. Pawlak, G. Pellizzi and M. Fiala. On the Development of Agricultural Mechanization to Ensure a Long- Term World Food Supply. Club of Bologna. Vol. IV. June 200
Project FACCE-JPI "Modifying canopy architecture and photosynthesis to maximize barley biomass and yield for different end-uses (BARPLUS)". III meeting 8th - 9th March 2018, Lleida (Spain). WP4 - Task 4.3: Environmental Assessment - preliminary results
- …