4D Tomography for neutron depth profiling applications Neagu, R.; Golenev, S.; Werner, L. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
August 2024, 2024-08-00, Volume:
1065
Journal Article
Peer reviewed
Open access
High-rate Neutron Depth Profiling (NDP) is a very efficient and precise probe for studying the evolution of lithium concentration in thin-layer structures, e.g., battery electrodes. NDP is typically ...limited to a one-dimensional depth analysis summed over the profile area covered by the neutron beam. We developed a detector system based on double-sided silicon strip detectors (DSSSD) with extremely thin and homogeneous entrance windows to provide a new quality of NDP measurements in 3+1 dimensions for the N4DP instrument at the FRM II in Garching, Germany. Using the 6Li(n, α)3H reaction in an experiment conducted at the research reactor in Delft, we achieved a lateral position resolution down to ∼100μm and an energy resolution with FWHM≈10keV for the triton particles at energies of 2.7MeV. High-resolution 3D pictures with a contrast uncertainty <10% per pixel can be achieved faster than 1 picture per minute. This rate can be adjusted individually for each experiment by sacrificing granularity in the position measurement.
Axial Flux Electrodynamic Maglev Motor (AFEMM), which 3D finite element method is time-consuming and analytical model has insufficient accuracy, is presented in this paper. Based on magnetic field ...reconstruction method (FRM) and second order vector potential (SOVP), a 3D calculation model of the motor, which the expression of magnetic field in the air gap, the lift force and torque were derived respectively, was proposed and verified by 3D transient finite element model. Finally, a small-scale prototype is manufactured, and experiments are carried out to verify the predicted results.
•State of the art on the confinement of masonry and concrete with FRM.•State of the art on analytical prediction of the compressive strength of FRM-column.•Two new DOMs for the FRM-confined ...column.•Two simplified versions of the proposed DOMs.
As well known the confinement is an effective intervention for increasing the compressive strength of an axially loaded column. During the decades, different materials have been adopted in order to provide confining action, such as steel, reinforced concrete and latest high-performance fibers. Fibers application resulted a powerful solution mainly because of the high ratio between mechanical properties and weight and the absence of electrochemical corrosion. On the other hand, fiber needs to be impregnated with a matrix in order to be applied around the column and to exert an effective confining pressure. Polymers manifest excellent performance in this role, but unfavorable result if breathability of the structural element is a key-issue as well as reversibility and compatibility of the new materials with the existing substrates (e.g. in historical masonry construction). In this scenario, the interest in non-polymeric matrix has been increased in the last years, as the use of a cement/lime based mortar.
In the present paper, a state-of-art regarding experimental programs on concrete and masonry samples confined by Fiber Reinforced Mortar (FRM) and subjected to pure compressive test is preliminary reported. Therefore, a multiple linear regression analysis was implemented in order to identify the possible influence of the interaction between the properties of the matrix and those of the fibers on the effectiveness of the confining pressure. Two new analytical formulations were assessed and discussed in the present study (the first related to concrete and the second related to masonry columns), evidencing the importance of taking into account the characteristics of the confining mortar besides those of fibers. A deep comparison (experimental vs. predicted) of the proposed formulae with Design-Oriented-Models (DOM) from the literature was also provided in terms of accuracy, precision and correlation. Finally, simplified relationships are also furnished and addressed to a possible contribution for design guidelines on the topic.
A detailed level numerical model for Fibre Reinforced Mortar (FRM) using the free, opensource code OOFEM has been recently calibrated and validated by the authors through comparisonwith experimental ...characterization tests (i.e. pull-off tests, tensile tests and shear bond tests). In thispaper, the developed model is adopted to perform numerical simulations on FRM strengthenedmasonry elements. In particular, out-of-plane and in-plane bending tests and in-plane diagonalcompressiontests are simulated by adopting the same modelling hypostasis and characteristics andthe results are compared with experimental tests available in the literature. Both the masonry and themortar are modeled through solid elements, the yarns of the fibre-based mesh with truss elements andthe interactions among the components (yarns, mortar, masonry) by means of interface elements.Non-linear static analyses are performed, considering the materials and interfaces non-linearity. Thesimulations result capable to realistically reproduce the typical performances of masonry elements interms of global performances and damage pattern and permit to investigate on the resistingmechanisms and on the interactions between the components.
Spectrum Sensing (SS) has been profoundly used in the Cognitive Radio (CR) framework due to its ability to identify spectrum holes and avoid intrusion for Primary Users (PUs). Several SS approaches ...based on filter banks (FBs) have been proposed in the literature. These techniques have the benefit of reusing the sensing filter bank for transmission as well, thereby providing an additional way to communicate at no extra cost. But the implementation complexity issues involved with the filter banks for CR were not taken into account. In this paper, we propose a Wideband Spectrum Sensing (WSS) based on a low complexity reconfigurable Modified FRM filter bank (ModFRM-FB) for detecting multiple active channels simultaneously. The proposed method uniformly divides the wideband signals into multiple-narrowband signals and each sub-band is sensed to evaluate the occupancy status of the sub-band by energy detection. Unlike traditional sensing algorithms, an adaptive threshold paradigm for energy detection is used to modify the threshold according to the noise power. This improves the detection performance even at low Signal-to-Noise Ratio (SNR) levels. The hardware complexity of our proposal is found to be comparatively lower than previous techniques in the literature.
Preaggregation Functions: Construction and an Application Lucca, Giancarlo; Sanz, Jose Antonio; Dimuro, Gracaliz Pereira ...
IEEE transactions on fuzzy systems,
2016-April, 2016-4-00, 20160401, Volume:
24, Issue:
2
Journal Article
Peer reviewed
Open access
In this paper, we introduce the notion of preaggregation function. Such a function satisfies the same boundary conditions as an aggregation function, but, instead of requiring monotonicity, only ...monotonicity along some fixed direction (directional monotonicity) is required. We present some examples of such functions. We propose three different methods to build preaggregation functions. We experimentally show that in fuzzy rule-based classification systems, when we use one of these methods, namely, the one based on the use of the Choquet integral replacing the product by other aggregation functions, if we consider the minimum or the Hamacher product t-norms for such construction, we improve the results obtained when applying the fuzzy reasoning methods obtained using two classical averaging operators such as the maximum and the Choquet integral.
Knowledge about fungi diversity following different planting patterns could improve our understanding of soil processes and thus help us to develop sustainable management strategies. The objective of ...this study was to determine the impact of different furrow-ridge mulching techniques on fungal diversity in rhizosphere soil under continuous cropping system. The investigated treatments were: flat plot without mulch (CK); flat plot with mulch (T1); on-ridge planting with full mulch (T2); on-furrow planting with full mulch (T3); on-ridge planting with half mulch (T4); and on-furrow planting with half mulch (T5). NGS (Illumina) methods and ITS1 sequences were used in monitoring fungi diversity of the potato rhizosphere soil. The fungi diversity in the rhizosphere soil was ranked in the order T5 > T2 > T4 > T1 > CK at the early growth stage and T2 > T3 > T1 > T4 > CK at the late growth stage of potato. The fungal communities found in the rhizosphere soil were Ascomycota, Zygomycota, Basidiomycota, Chytridiomycota, and other unidentified fungal communities. Among the fungal community in the rhizosphere soil, Ascomycota was found to be dominant fungi population, with the highest percentage (89%) in the T5 soil whereas the T2 soils had the lowest percentage (67%). The
abundance in fully-mulched treated soils was higher than in half-mulched treated soil. The dominant genus in the T4 soil was
, whereas lower populations (1-2%) of
,
,
, and
were found in that treatment. Among the eumycetes, the dominant fungal class in all treated soils was the Sordariomycetes, which ranged from 57 to 85% in T2 and T5 soils, respectively. The
percentages in half-mulched treated soils (T4 and T5) were 55 and 28% lower than that of complete mulched treated soils (T2 and T3), respectively. The cluster analysis results showed that, CK, T4, and T5 treated soils and T1, T2, and T3 treated soils had similarities in microbial compositions, respectively. Potato tuber yield was greater under the on-ridge planting with full mulch (T2) treated soil, followed by on-ridge planting with half-mulch (T4) treated soil. The rhizosphere soil under the on-ridge planting with full-mulch (T2) soil had the highest fungal diversity, suggesting that this management was the best environment for fungi, whereas the on-ridge planting with half-mulch (T4) soil had the minimum abundance of
•The effect of different FRM laser powers on weld morphology has been investigated.•The difference in the suppression of welding spatter for different laser combination modes of FRM laser welding has ...been studied.•The relation between microstructure and mechanical properties of the FRM welded joints has been revealed.
Flexible Ring Mode (FRM) laser welding is a relatively new composite laser welding technology. The present study focused on the FRM laser welded joints produced from 4.5 mm-thick 304 stainless steel. The effects of various laser modes on the macroscopic morphology, microstructure, microhardness, and tensile properties of the produced welded joints were systematically investigated. The results showed that, when the ring laser power was set at 1000 W and the center laser power at 3000 W, a maximum weld area of 6.23 mm2 was obtained. Employing a composite laser with a center laser power greater than the ring laser power resulted in the fewest number of welding spatter particles on both sides of the weld bead, indicating an effective inhibition of welding spatter by the ring laser. Conversely, using a composite laser with a center laser power equal to the ring laser power still led to the presence of small welding spatter particles, indicating differences in the laser combination modes in suppressing welding spatter for the welding of 304 stainless steel. Increased cooling and a large presence of small turbulence contributed to the grain refinement in the fusion zone of the welded joints produced using a composite laser with a central laser power greater than the ring laser power. Consequently, this welded joint exhibited the highest maximum tensile strength among all tensile test specimens reaching 95.2 % of the base metal’s maximum tensile strength. However, the fractured surfaces of the tensile test specimens produced using a composite laser with a center laser power equal to the ring laser power exhibited the highest number density and largest size of oxide particles, resulting in a joint elongation of only 77.3 % of the base metal’s elongation. This study emphasizes the potential application of this FRM laser and provides theoretical guidance for selecting the optimal laser combination mode for FRM laser welding of stainless steel.
•In its natural distribution area Turkish hazel has been overexploited because of its valuable wood and can only be found in small and isolated populations.•Therefore, we examined the genetic ...structure and variation of Turkish hazel covering most of its natural distribution area in Asia Minor, the Caucasus, and the Balkan Peninsula.•Altogether, 689 Turkish hazel trees from 25 populations based on 15 nuclear and five chloroplast microsatellite markers were studied.•Both data sets revealed distinct genetic structures of Turkish hazel in its natural distribution range, suggesting separate refugia and migration pathways during the Holocene.•Medium to high level genetic variation was found, with somewhat lower values in Georgia and Turkey compared to the Balkan populations.•Overall, our results highlight needs to delineate provenance regions, identify conservation units and seed stands for Turkish hazel which are essential for species conservation, provenance research and possible assisted migration attempts.•Based on our results each country is able now to start the conservation programs and select GCUs for Turkish hazel.
Climate change is already affecting all forest ecosystems and threatening species therein. By establishing mixed forests incorporating other tree species (e. g. scattered broadleaves) adaptation of forest stands to changing environmental conditions can be improved and the risks minimized. Turkish hazel (Corylus colurna L.) has been currently discussed as a valuable so-called alternative tree species in some European regions because it is well adapted to difficult environmental conditions. However, in its natural distribution area Turkish hazel has been overexploited because of its valuable wood and can only be found in small and isolated populations. Therefore, we examined the genetic structure and variation of Turkish hazel covering most of its natural distribution range in Asia Minor, the Caucasus, and the Balkan Peninsula. Altogether, 689 Turkish hazel trees from 25 populations were analysed at 15 nuclear and five chloroplast microsatellite markers. Both data sets revealed distinct genetic clusters of Turkish hazel in its natural distribution range, suggesting separate refugia and migration pathways during the Holocene. Medium to high level genetic variation was found, with somewhat lower values in Georgia and Turkey compared to the Balkan populations. Overall, our results highlight the need to delineate provenance regions, identify gene conservation units (GCUs) and seed stands for Turkish hazel which are essential for species conservation, provenance research and possible assisted migration attempts. Based on our results each country is able now to start conservation programs and select GCUs for Turkish hazel.
Exploring the neural encoding mechanism and decoding of motion state switching during flight can advance our knowledge of avian behavior control and contribute to the development of avian robots. ...However, limited acquisition equipment and neural signal quality have posed challenges, thus we understand little about the neural mechanisms of avian flight.
We used chronically implanted micro-electrode arrays to record the local field potentials (LFPs) in the formation reticularis medialis mesencephali (FRM) of pigeons during various motion states in their natural outdoor flight. Subsequently, coherence-based functional connectivity networks under different bands were constructed and the topological features were extracted. Finally, we used a support vector machine model to decode different flight states.
Our findings indicate that the gamma band (80-150 Hz) in the FRM exhibits significant power for identifying different states in pigeons. Specifically, the avian brain transmitted flight related information more efficiently during the accelerated take-off or decelerated landing states, compared with the uniform flight and baseline states. Finally, we achieved a best average accuracy of 0.86 using the connectivity features in the 80-150 Hz band and 0.89 using the fused features for state decoding.
Our results open up possibilities for further research into the neural mechanism of avian flight and contribute to the understanding of flight behavior control in birds.
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