2,788 research outputs found
Electromagnetic wave absorption and structural properties of wide-band absorber made of graphene-printed glass-fibre composite
Lightweight composites combining electromagnetic wave absorption and excellent mechanical properties are required in spacecraft and aircraft. A one- dimensional metamaterial absorber consisting of a stack of glass fibre/epoxy layers and graphene nanoplatelets/epoxy films was proposed and fabricated through a facile air-spraying based printing technology and a liquid resin infusion method. The production process allows an optimum dispersion of graphene nanoplatelets, promoting adhesion and mechanical integration of the glass fibre/epoxy layers with the graphene nanoplatelets/epoxy films. According to experimental results, the proposed wide-band absorber provides a reflection coefficient lower than â10 dB in the range 8.5â16.7 GHz and an improvement of flexural modulus of more than 15%, with a total thickness of âŒ1 mm. Outstanding electromagnetic wave absorption and mechanical performance make the proposed absorber more competitive in aeronautical and aerospace applications
Assessing the volcanic hazard for Rome. 40Ar/39Ar and In-SAR constraints on the most recent eruptive activity and present-day uplift at Colli Albani Volcanic District
We present new 40Ar/39Ar data which allow us to refine the recurrence time for the most recent eruptive activity occurred at Colli Albani Volcanic District (CAVD) and constrain its geographic area. Time elapsed since the last eruption (36 kyr) overruns the recurrence time (31 kyr) in the last 100 kyr. New interferometric synthetic aperture radar data, covering the years 1993â2010, reveal ongoing inflation with maximum uplift rates (>2 mm/yr) in the area hosting the most recent (<200 ka) vents, suggesting that the observed uplift might be caused by magma injection within the youngest plumbing system. Finally, we frame the present deformation within the structural pattern of the area of Rome, characterized by 50 m of regional uplift since 200 ka and by geologic evidence for a recent (<2000 years) switch of the local stress-field, highlighting that the precursors of a new phase of volcanic activity are likely occurring at the CAVD
Propagation of Chaos for a Thermostated Kinetic Model
We consider a system of N point particles moving on a d-dimensional torus.
Each particle is subject to a uniform field E and random speed conserving
collisions. This model is a variant of the Drude-Lorentz model of electrical
conduction. In order to avoid heating by the external field, the particles also
interact with a Gaussian thermostat which keeps the total kinetic energy of the
system constant. The thermostat induces a mean-field type of interaction
between the particles. Here we prove that, starting from a product measure, in
the large N limit, the one particle velocity distribution satisfies a self
consistent Vlasov-Boltzmann equation.. This is a consequence of "propagation of
chaos", which we also prove for this model.Comment: This version adds affiliation and grant information; otherwise it is
unchange
Advances in Food Processing Through Radio Frequency Technology: Applications in Pest Control, Microbial and Enzymatic Inactivation
Foodborne illnesses occur due to contamination by pathogenic microorganisms. Therefore, decontaminating food is vital before marketing and circulation. Radio frequency (RF) heating stands out in several branches of industry, mainly food processing, as an alternative method to conventional pasteurization which takes long process times and overheating. RF heating functions without relying on heat conduction. It generates internal heat by inducing the rotation of polar molecules and the motion of ions. The advantages of dielectric heating with greater wave penetration include rapid, uniform and volumetric heating, presenting high energy efficiency. Furthermore, it is an effective, validated method for eliminating pathogens in agricultural products and is free from chemical residues. Although many reviews have discussed this technology, few reviews have covered the research trends in this field in the recent years, during which the number of studies discussing RF treatment of foods have increased. Therefore, this review focuses on the RF applications in the food industry for pest control, microbial and enzymatic inactivation of solid, liquid, and powdered foods in the last five years. Besides covering the fundamental aspects of RF technology, we also examine its benefits and drawbacks, address the challenges it presents, and explore future prospect
Accurate Modeling of Weak Lensing with the sGL Method
We revise and extend the stochastic approach to cumulative weak lensing
(hereafter the sGL method) first introduced in Ref. [1]. Here we include a
realistic halo mass function and density profiles to model the distribution of
mass between and within galaxies, galaxy groups and galaxy clusters. We also
introduce a modeling of the filamentary large-scale structures and a method to
embed halos into these structures. We show that the sGL method naturally
reproduces the weak lensing results for the Millennium Simulation. The strength
of the sGL method is that a numerical code based on it can compute the lensing
probability distribution function for a given inhomogeneous model universe in a
few seconds. This makes it a useful tool to study how lensing depends on
cosmological parameters and its impact on observations. The method can also be
used to simulate the effect of a wide array of systematic biases on the
observable PDF. As an example we show how simple selection effects may reduce
the variance of observed PDF, which could possibly mask opposite effects from
very large scale structures. We also show how a JDEM-like survey could
constrain the lensing PDF relative to a given cosmological model. The updated
turboGL code is available at turboGL.org.Comment: PRD style: 20 pages, 10 figures; replaced to match the improved
version accepted for publication in PRD. The updated turboGL code can be
downloaded at http://www.turbogl.org
Conditional Adversarial Camera Model Anonymization
The model of camera that was used to capture a particular photographic image
(model attribution) is typically inferred from high-frequency model-specific
artifacts present within the image. Model anonymization is the process of
transforming these artifacts such that the apparent capture model is changed.
We propose a conditional adversarial approach for learning such
transformations. In contrast to previous works, we cast model anonymization as
the process of transforming both high and low spatial frequency information. We
augment the objective with the loss from a pre-trained dual-stream model
attribution classifier, which constrains the generative network to transform
the full range of artifacts. Quantitative comparisons demonstrate the efficacy
of our framework in a restrictive non-interactive black-box setting.Comment: ECCV 2020 - Advances in Image Manipulation workshop (AIM 2020
Cold-Sprayed Al6061 coatings. Online spray monitoring and influence of process parameters on coating properties
Process optimization and quality control are important issues in cold spraying and coating development. Because the cold spray processing is based on high kinetic energy by high particle velocities, online spray monitoring of particle inflight properties can be used as an assisting process tool. Particle velocities, their positions in the spray jet, and particle size measurements give valuable information about spraying conditions. This, in turn, improves reproducibility and reliability of coating production. This study focuses on cold spraying of Al6061 material and the connections between particle inflight properties and coating characteristics such as structures and mechanical properties. Furthermore, novel 2D velocity scan maps done with theHWCS2 online spray monitoring system are presented as an advantageous powder and spray condition controlling tool. Cold spray processing conditions were similar using different process parameters, confirmed with the online spray monitoring prior to coating production. Higher particle velocities led to higher particle deformation and thus, higher coating quality, denser structures, and improved adhesions. Also, deposition efficiency increased significantly by using higher particle velocities
A database of ocean primary productivity from the 14C method
The database on ocean primary productivity comprises over two decades (1985â2008) of data that the authors have participated in collecting, using the assimilation of inorganic 14C through photosynthesis, in incubations carried out in situ. The dataset is perhaps unique in that it uses, overwhelmingly, consistent methodology while covering a wide geographic range. Ancillary data are included. Using the database, it is hoped that investigators can test for the relationships among the environmental drivers for ocean productivity, the meaning of the 14C method in terms of phytoplankton physiology and the dynamics in the water column, and as a resource for further development of productivity algorithms using satellite ocean color imagery
Transcriptomic Analysis of the Pistacia vera (L.) Fruits Enable the Identification of Genes and Hormone-Related Gene Linked to Inflorescence Bud Abscission
Pistacia vera (L.) is an alternate bearing species. The tree produces axillary inflorescence buds every year. Still, they abscise in âONâ overloaded shoots, causing a limited production in the following âOFFâ year, causing a significant and unfavorable production fluctuation. In this work, we carried out de novo discovery and transcriptomic analysis in fruits of âONâ and âOFFâ shoots of the cultivar Bianca. We also investigated whether the fruit signaling pathway and hormone biosynthesis directly or indirectly linked to the premature fall of the inflorescence buds causing alternate bearing. We identified 1536 differentially expressed genes (DEGs) in fruits of âONâ vs. âOFFâ shoots, which are involved primarily in sugar metabolism, plant hormone pathways and transcription factors. The premature bud abscission linked to the phenomenon is attributable to a lack of nutrients (primarily sugar) and the possible competition between the same branchesâ sinks (fruits vs. inflorescence buds). Hormone pathways are involved as a response to signals degradation and remobilization of carbon and nutrients due to the strengthening of the developing embryos. Genes of the secondary metabolism and transcription factors are also involved in tailoring the individual branches response to the nutritional stress and sink competition. Crosstalk among sugar and various hormone-related genes, e.g., ethylene, auxin, ABA and cytokinin, were determined. The discovery of putative biomarkers like callose synthase 5, trehalose-6-phosphate synthase, NAD(P)-linked oxidoreductase and MIOX2, Jasmonate, and salicylic acid-related genes can help to design precision farming practices to mitigate the alternate bearing phenomenon to increase farming profitability. The aim of the analysis is to provide insight into the gene expression profiling of the fate of âONâ and âOFFâ fruits associated with the alternate bearing in the pistachio
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