Horizontal Elongation Research Articles

The Similarity of Quasi-geostrophic Vortices Against the Background of Large-Scale Barotropic Currents

The paper proposes a theory of similarity of quasi-geostrophic vortices against the background of large-scale flows. This information is useful when planning laboratory and numerical experiments to study mesoscale and submesoscale vortex dynamics of vortices interacting with currents. Special attention is paid to the study of geometric similarity of phenomena. It is revealed that the complete set of dimensionless similarity numbers of baroclinic vortices includes four dimensionless parameters: the dimensionless intensity of the vortex, the geometric similarity of the background flow (the ratio of relative vorticity to the deformation coefficient of the background flow), the coefficient of horizontal elongation of the vortex core and the coefficient of vertical oblateness of the vortex core coinciding with the Burger number. To describe the similarity of barotropic vortices against the background of barotropic flows, the number of necessary dimensionless parameters is reduced by one number — the coefficient of vertical oblateness of the vortex core is eliminated from consideration. When studying axisymmetric vortices or vortex structures close to axisymmetric, another geometric parameter of the vortex is eliminated from consideration — the coefficient of horizontal elongation of the vortex core. As a result, the maximum possible set of similarity parameters includes four dimensionless numbers, and the minimum is two.

Auricular spoon-shaped crus malformation including variants: Clinical features and a novel surgical approach

BackgroundCertain auricular malformations are uncommon and lack generally accepted diagnostic names. This study investigates an uncommon complex auricular malformation known as auricular spoon-shaped crus malformation providing a detailed description of its external characteristics. Additionally, an effective surgical approach is proposed. MethodsBetween 1991 and 2023, 12 auricles from 11 patients with as the auricular spoon-shaped crus malformation including variants were surgically treated at our center. Patient medical records and photographic data were retrospectively reviewed. ResultsEach auricle exhibited 2 to 4 major structural deformities within the five areas of the superior crus, inferior crus and stem of the antihelix, helical crus, and earlobe. These deformities resulted in depression between the antihelix and antitragus, vertical shortening, horizontal elongation of the auricle, and/or drooping of the ear. Three patients displayed a low positioning of the malformed ear, and eight patients exhibited mild to moderate hemifacial microsomia. Earlier corrections we conducted utilized various methods with variable aesthetic outcomes. Recently, the improved corrective method we implemented yielded consistently promising aesthetic results. We have confidence that adopting the surgical approach we suggest can lead to promising aesthetic results when addressing this malformation. Furthermore, we hope that the presented malformation will be recognized as a primary auricular malformation by auricular surgeons in the future.

Underwater additive manufacturing of 10CrNi3MoV high-strength low-alloy steel by wire-feed laser melting deposition: Effect of microstructure evolution on mechanical properties

The underwater 10CrNi3MoV high-strength low-alloy steel thin-walled part with forming quality up to in-air laser deposition quality was successfully manufactured for the first time. The influencing mechanisms of complicated thermal history and water environment on microstructure evolution and mechanical properties of thin-walled part were researched. Due to austenitization and interlocking effect, the microstructure in the bottom, middle and top (below the 56th layer) areas of underwater sample and the middle area of in-air sample were composed of fine grain ferrite and granular bainite. With the increase of building height, the heat accumulation effect of underwater sample enhanced, resulting in small grain size (GS), high dislocation density, strong solution strengthening effect and low maximum texture strength at the bottom area, while the high proportion of high-angle grain boundaries (HAGBs) at the top area. These resulted in the greatest tensile strength (714 MPa) and microhardness (232 HV) at the bottom area and the highest elongation (11%) at the top area. Due to the cooling effect of water environment, the proportion of HAGBs reduced and there were oxides in fracture. As a result, the horizontal elongation of underwater sample was about 90.9% of in-air sample. Additionally, the GS reduced, and the dislocation density and solution strengthening effect increased, so the microhardness of underwater sample was slightly higher than that of in-air sample. However, due to some microscopic defects, the horizontal and vertical tensile strength of underwater sample were about 97.6% and 90.7% of in-air sample.

Experimental design of 4-point supported belt robot for sanding large convex surfaces

In general, sanding robots that move as if drawing a line along a surface are mainly used when sanding objects with a large area; however, they require a long working time, and it is difficult to secure a uniform sanded area. This study focuses on large-area sanding robots, such as those for ships, storage tanks, and tank lorries, and proposes an adaptive belt tension robot equipped with a 4-point supported belt mechanism capable of sanding variable curved surfaces. In addition, a sanding normal force prediction formula is proposed to describe the sanding performance of the contact surface. This equation consists of the concentrated load function due to the belt movement and the normal force due to the vertical and horizontal elongation of the belt. A video image analysis was performed to calculate the sanding area. Therefore, we determined whether the area was uniformly sanded. The dimensions of the test bench (W ×\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\ imes $$\\end{document} D ×\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\ imes $$\\end{document} H) were 1700 mm ×\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\ imes $$\\end{document} 1450 mm ×\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\ imes $$\\end{document} 900 mm. Experiments were performed using the proposed techniques on convex specimens with radii of 725, 1000, and 2100 mm. The sanding performance was improved by 43 %\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\%$$\\end{document} compared with that of a general belt-sanding robot.

Research on a Locking Device for Power-Off Locking and 2-DOF Backward Motion Suppression of a Piezoelectric Platform

Inertial positioning platforms driven by piezoelectric actuators have been employed in many precision applications. However, challenges including unstable pose keeping and intractable displacement backward still exist. In this study, a locking device is designed and embedded in a piezoelectric inertial rotary platform to achieve the functions of power-off locking and 2-DOF backward motion suppression. The vertical output displacement of the locking end is converted from the horizontal elongation of the PZT stack by the flexible hinge mechanisms of the locking device, which is used to lock the rotor of the rotary platform. Theoretical and simulation analyses of the locking mechanism are performed and its dominant parameters are optimized. A prototype is fabricated and a series of experiments are performed. Compared with the inertial rotary platform without the locking device, the locking ability is increased by 4.55 times and the backward ratio is reduced from over 60% to below 12%. The application of locking device not only improves the pose keeping ability of the inertial positioning platform, but also improves its displacement output characteristics through backward motion suppression.

Hydrophobic self-cleaning micro-nano composite polyethylene-based agricultural plastic film with light conversion and abrasion resistance

Agricultural plastic film (APF) is extensively used in modern agriculture. However, to the best of our knowledge, the self-cleaning property and light transmittance of APF are still the main factors affecting crop yield at present. To solve these problems, for the first time, we developed polyethylene-based dust-proof composite APF with multi-scale micro-nano structure and light conversion performance. By combining the carbon dots (CDs) and hydrophobic silica nanoparticles (FSi-SiO2) with organically modified montmorillonite (OMMT), composite materials with multi-scale micro-nano structure and low surface energy (SFE) were constructed (FSi-SiO2/CDs@OMMT). After blending with linear low-density polyethylene (LLDPE, PE), a self-cleaning dust-proof APF with “lotus-effect” was synthesized (PE/FSi-SiO2/CDs@OMMT). The PE/FSi-SiO2/CDs@OMMT exhibited excellent hydrophobic property, which had a water contact angle (WCA) of 108.9°. The results of the mechanical properties tests showed that the horizontal and portrait tensile strength of PE/FSi-SiO2/CDs@OMMT improved from 25.08 and 27.41 MPa to 33.14 and 42.21 MPa and that the horizontal and portrait elongation at break improved from 273.53 % and 380.23–369.43 % and 480.73 %, respectively. In addition, the anti-fouling and dust-proof performance were studied, and the results showed that the anti-fouling rate and dust removal efficiency of PE/FSi-SiO2/CDs@OMMT were reached to 99.84 % and 99.58 %, respectively. Additionally, PE/FSi-SiO2/CDs@OMMT also possessed excellent thermal stability, anti-algae and anti-bacterial adhesion properties, and light conversion performance. This work could provide a facile approach and strategy to fabricate functional APF for agricultural application.

Ecological factors are likely drivers of eye shape and colour pattern variations across anthropoid primates

External eye appearance across primate species is diverse in shape and colouration, yet we still lack an explanation for the drivers of such diversity. Here we quantify substantial interspecific variation in eye shape and colouration across 77 primate species representing all extant genera of anthropoid primates. We reassess a series of hypotheses aiming to explain ocular variation in horizontal elongation and in colouration across species. Heavier body weight and terrestrial locomotion are associated with elongated eye outlines. Species living closer to the equator present more pigmented conjunctivae, suggesting photoprotective functions. Irises become bluer in species living further away from the equator, adding to existing literature supporting a circadian clock function for bluer irises. These results shift the current focus from communicative, to ecological factors in driving variation in external eye appearance in anthropoid primates. They also highlight the possibility that similar ecological factors contributed to selection for blue eyes in ancestral human populations living in northern latitudes.

Interface extension is a continuum property suggesting a linkage between AP contractile and DV lengthening processes.

In the early Drosophila embryo, the elongation of the anterior-posterior (AP) body axis is driven by cell intercalation in the germband epithelium. Neighboring cells intercalate through the contraction of AP interfaces (between AP neighbors) into higher-order vertices, which then resolve through the extension of new dorsal-ventral (DV) interfaces (between DV neighbors). Although interface contraction has been extensively studied, less is known about how new interfaces are established. Here we show that DV interface elongation behaviors initiate at the same time as AP contractions, and that DV interfaces which are newly created from resolution of higher-order vertices do not appear to possess a unique 'identity;' instead, all horizontal interfaces undergo lengthening, elongating through ratchetlike sliding behaviors analogous to those found in AP interfaces. Cortical F-actin networks are essential for high area oscillation amplitudes required for effective ratcheting. Our results suggest that, contrary to canonical models, the elongation of new DV interfaces is not produced by a mechanistically separate process. Instead, medial myosin populations drive oscillating radial forces in the cells to generate transient force asymmetries at all tricellular vertices, which-combined with planar polarized stabilization-produce directional ratcheted sliding to generate both AP interface contraction and DV interface elongation.

Reconstruction of Cymodocea nodosa’s dynamics as a tool to examine the conservation status of a Mediterranean declared marine protected area

Seagrass habitats rank amongst the most valuable ecosystems in the biosphere. They support fisheries production, climate change mitigation, water quality improvement, and coastal protection. Faced with the current global crisis of accelerating losses of this key component of coastal environments, strong efforts have been expended within the conservation movement to flatten their decline curve. Although understanding the functioning of seagrass ecosystems and how they respond to stressors has improved over the last years, major gaps exist for West Africa including basic ecological and distributional knowledge. This study aimed to investigate, for the first time, the structural development and dynamics of two Cymodocea nodosa meadows in Al Hoceima National Park (the unique official marine protected area of the Mediterranean Moroccan coast) using the reconstruction techniques as an indirect measurement of seagrass growth. C. nodosa’s leaves were remarkably invaded by epiphytes while leaf production, shoot density, above and belowground biomass, and vertical and horizontal rhizome elongation were in the lowest recorded values. Shoot age structure showed that since the second-year class, the survival rate of shoots has decreased. Regarding the severely slow recruitment rates, the populations’ net growths declined. Besides this negative growth trend, CymoSkewm biotic index assigned a slightly polluted ecological status to both meadows. The seagrass faces numerous pressures, mainly fishing by trawling and alien species invasion. The primary conservation challenge for C. nodosa of Al Hoceima National Park is ensuring that this marine protected area becomes operationally implemented and actively managed. Until then, the seagrass habitat-forming species is not safeguarded.

Microstructure and mechanical properties of Wire Arc Additive Manufactured (WAAM) Inconel 718 parts via post heat treatments

As-printed Inconel 718 usually cannot meet general requirements on mechanical properties, and post heat treatments are required to homogenize alloying elements and foster uniform precipitation. In this paper, we investigated into post heat treatment plans for WAAM-printed Inconel 718, with optimized solution annealing and single-step age hardening to improve overall mechanical properties. After heat treatment, Laves phase was fully dissolved with well controlled grain size and precipitates. The resulting yield strength along building direction was increased by 85% with average vertical elongation of 27.5% and horizontal elongation of 34%. Moreover, Charpy impact testing was also conducted, and an average impact value of 46 J was achieved at −60 °C, which was 100% higher than the coupon processed with the standard heat treatment plan.

Eye movements elevate crowding in idiopathic infantile nystagmus syndrome.

Idiopathic infantile nystagmus syndrome is a disorder characterised by involuntary eye movements, which leads to decreased acuity and visual function. One such function is visual crowding – a process whereby objects that are easily recognised in isolation become impaired by nearby flankers. Crowding typically occurs in the peripheral visual field, although elevations in foveal vision have been reported in congenital nystagmus, similar to those found with amblyopia. Here, we examine whether elevated foveal crowding with nystagmus is driven by similar mechanisms to those of amblyopia – long-term neural changes associated with a sensory deficit – or by the momentary displacement of the stimulus through nystagmus eye movements. A Landolt-C orientation identification task was used to measure threshold gap sizes with and without either horizontally or vertically placed Landolt-C flankers. We assume that a sensory deficit should give equivalent crowding in these two dimensions, whereas an origin in eye movements should give stronger crowding with horizontal flankers given the predominantly horizontal eye movements of nystagmus. We observe elevations in nystagmic crowding that are above crowding in typical vision but below that of amblyopia. Consistent with an origin in eye movements, elevations were stronger with horizontal than vertical flankers in nystagmus, but not in typical or amblyopic vision. We further demonstrate the same horizontal elongation in typical vision with stimulus movement that simulates nystagmus. Consequently, we propose that the origin of nystagmic crowding lies in the eye movements, either through image smear of the target and flanker elements or through relocation of the stimulus into the peripheral retina.

비신축성 직물의 고무 밴드 봉제 조건에 따른 신장 특성 분석

This study analyzes how sewing conditions for elastic bands on woven fabrics affect elongation. The directions of the elastic bands were vertical, horizontal, vertical and horizontal crossing, and horizontal and vertical crossing. Intervals between the elastic bands were 3.0 cm and 6.0 cm. The woven fabric was tailored for the elastic band sewing using warp, weft, and bias. Consequently, it was possible to visually confirm elongation differences according to the sewing condition of the elastic bands. A detailed examination demonstrated that the horizontal or vertical placement of elastic bands tailored in a crosswise direction produces high vertical elongation and low horizontal contraction. However, elastic bands sewed in crossing directions, regardless of warp and weft directions, resulted in both high vertical elongation and high horizontal contraction. In all cases, the more elastic bands were used, the higher the horizontal elongation. In conclusion, appropriate placements of elastic bands on woven fabric increases motion convenience.

Refined orthotropic beam models based on Castigliano’s theorem and an approximate solution of the compatibility equation

This paper presents an extension of Castigliano’s second theorem for orthotropic beams. The notion “extension” in this context means to find more accurate results not only for the vertical deflection, but also for the horizontal deflection and the rotation angle. For this purpose the Airy stress function is calculated for an orthotropic rectangular strip based on the iterative approximation method from Boley-Tolins when distributed loads or shear tractions are assumed as surface loads. Hence all stress components can be derived from the stress function and may be inserted into the complementary strain energy. Computing the partial derivative of the complementary strain energy with respect to a scalar dummy parameter, the weighted displacement field components over the cross section are obtained. Finally the analytical results from the extended Castigliano theorem (ECT) are verified by two-dimensional (2D) analytical results for an orthotropic cantilever and a clamped-hinged beam and the outcome is also compared to Bernoulli–Euler and to Timoshenko results. The accuracy of the derived results is higher than that derived by the Timoshenko theory because the normal stress in thickness direction is properly taken into account. Moreover it is demonstrated that this lower order normal stress which is caused by distributed loads yields a mean horizontal elongation or shrinkage that is not considered by the Timoshenko beam theory. Hence, highly accurate formulations for laminated composite beams, involving sandwich-structures or multi-layered beams with imperfect bonding, may be derived from the present orthotropic beam model in the future.

Intermittent dynamic bursting in vertically vibrated liquid drops

A previously unreported regime of type III intermittency is observed in a vertically vibrated milliliter-sized liquid drop submerged in a more viscous and less dense immiscible fluid layer supported by a hydrophobic solid plate. As the vibration amplitude is gradually increased, subharmonic Faraday waves are excited at the upper surface of the drop. We find a narrow window of vibration amplitudes slightly above the Faraday threshold, where the drop exhibits an irregular sequence of large amplitude bursting events alternating with intervals of low amplitude activity. Our experimental results and the suggested phenomenological model directly link the onset of the intermittent bursting regime in an isolated liquid drop to the competition between two hydrodynamic modes: the surface Faraday waves and the shape deformation mode, responsible for the horizontal drop elongation.

Long-term effects of elevated CO2 on the population dynamics of the seagrass Cymodocea nodosa: Evidence from volcanic seeps

Population reconstruction techniques was used to assess for the first time the population dynamics of a seagrass, Cymodocea nodosa, exposed to long-term elevated CO2 near three volcanic seeps and compared them with reference sites away from the seeps. Under high CO2, the density of shoots and of individuals (apical shoots), and the vertical and horizontal elongation and production rates, were higher than at the reference sites. Nitrogen limitation effects on rhizome elongation and production rates and on biomass were more evident than CO2 as these were highest at the location where the limitation of nitrogen was highest. At the seep where the availability of CO2 was highest and nitrogen lowest, density of shoots and individuals were highest, probably due to CO2 effects on shoot differentiation and induced reproductive output, respectively. At the three seeps, there was higher short- and long-term shoot recruitment than at the reference sites, and growth rates was around zero, indicating that elevated CO2 increases the turnover of C. nodosa shoots.

DEFORMATIONS IN THE MIDDLE AMERICA TRENCH ACCORDING TO EARTHQUAKE FOCAL MECHANISMS AND THEIR FEATURES IN THE AREA OF THE 2017 МW 8.2 CHIAPAS EARTHQUAKE, MEXICO

Seismotectonic deformations in the Middle America Trench and their features in the area of preparation of the Chiapas earthquake, М W =8.2, 08 September 2017, were determined using the data on 2244 focal mechanisms of earthquakes for the period of 1977–2017. The distribution of seismicity with depth was studied in detail. The decrease in the depth of the Benioff zone in the north-western subduction segments and the increase in the south-eastern segments is associated with the age of the subducting parts of the Cocos plate and the angle of their immersion. The latter mechanism can also explain the presence of earthquakes with normal focal mechanism on the oceanic uplift in the south-eastern segments of the subduction zone and their absence in the north-western ones. In general, the typical character of subduction deformations has a number of features in the Middle America Trench. The predominance of shortening by horizontal components and elongation by vertical ones at depths up to 35 km is replaced by the transitional type with mosaic distribution of deformations of different signs in the depth range of 36–70 km. Even lower, in the depth range of 70–105 km, the type of deformation changes to the opposite with respect to the upper horizon. The Chiapas earthquake occurred on the border of regions with different types of deformation, which indicates softening of the block’s medium to the west of the hypocenter and its hardening to the east. Such a state of the lithospheric medium may indicate the presence of a deformation shadow zone in the Chiapas earthquake preparation area.

Effect of Mg Content on Microstructure and Properties of Al-Mg Alloy Produced by the Wire Arc Additive Manufacturing Method.

In this study, an Al–Mg alloy was fabricated by wire arc additive manufacture (WAAM), and the effect of Mg content on the microstructure and properties of Al–Mg alloy deposits was investigated. The effects on the deposition surface oxidation, geometry, burn out rate of Mg, pores, microstructure, mechanical properties and fracture mechanisms were investigated. The results show that, when the Mg content increased, the surface oxidation degree increased; a “wave”-shaped deposition layer occurred when the Mg content reached 8%. When the Mg content was more than 6%, the burning loss rate of the Mg element increased significantly. With the increase of Mg content, the number of pores first decreased and then increased, and the size first decreased and then increased. When the Mg content reached 7% or above, obvious crystallization hot cracks appeared in the deposit bodies. When the Mg content increased, the precipitated phase (FeMn)Al6 and β(Mg2Al3) increased, and the grain size increased. When the Mg content was 6%, the comprehensive mechanical properties were best. The horizontal tensile strength, yield strength and elongation were 310 MPa, 225 MPa and 17%, respectively. The vertical tensile strength, yield strength and elongation were 300 MPa, 215 MPa and 15%, respectively. The fracture morphology was a ductile fracture.

Directive surface wave on nanoplasmonic film: the roles of photonic spin-Hall effect and optical interactions

Interaction of the spin and orbital angular momentum of light, occurring in the photonic spin Hall effect (PSHE), leads to the separation of photons with opposite spins (two different forms of circularly polarized wave) toward opposite directions perpendicular to the pump light-beam path. As photons with two opposite spins illuminate a nanoparticle (NP) near a metal–dielectric interface (MDI), the associated evanescent fields excite spin-dependent directional surface plasmon polaritons (SPPs) with transverse spins. We show that a circularly polarized incident optical beam, which contains only one spin state, causes the directional scattering of SPPs on the nanoplasmonic-film surface, following the PSHE. Here, Green’s tensor approach in conjunction with the mode-matching technique are developed and employed to describe this effect. Based on quasi-static modeling, the effects of crucial parameters on the directive propagating of the confined surface wave and on its corresponding directional pattern are theoretically and numerically studied. Interestingly, the theoretical results, adequately confirmed by the computations, demonstrate that an excited plasmonic NP with a little horizontal elongation to modify internal electric polarization of the NP remarkably enhances the PSHE, resulting in almost unidirectional scattering of the launched SPP on the MDI. The findings pave a way for SPP-based engineering applications and multichannel photonic communications.

Comprehensive Transcriptome Reveals an Opposite Regulatory Effect of Plant Growth Retardants in Controlling Seedling Overgrowth between Roots and Shoots.

Seedling overgrowth always develops in undernourished plants due to biotic or abiotic stresses, which significantly decrease the yield of crops and vegetables. It is known that the plant growth retardants paclobutrazol (PBZ) and chlormequat chloride (CCC) are the most commonly used chemicals in controlling seedling height in plants by regulating the gibberellin (GA) biosynthesis pathway. However, the exact molecular regulation mechanism remains largely unknown. This study performed a comprehensive transcriptome profile to identify significantly differentially expressed genes after adding CCC and PBZ to the water culture seedling raising system for the first time. According to the obviously restrained shoots and roots, the GA biosynthesis genes were significantly decreased, as well as the endogenous GA content being reduced. Intriguingly, the GA signaling pathway genes were affected in opposite ways, increasing in roots but decreasing in shoots, especially regarding the phytochrome interacting factor SlPIF1 and the downstream genes expansins (SlEXPs), which promote cell wall remodeling. Further study found that the most down-regulated genes SlEXPA5 and SlEXPA15 were expressed specifically in shoot tissue, performing the function of repressing elongation, while the up-regulated genes SlEXPB2 and SlEXPB8 were proven to be root-specific expressed genes, which may promote horizontal elongation in roots. This research reported the comprehensive transcriptome profiling of plant growth retardants in controlling seedling overgrowth and restraining GA biosynthesis through the regulation of the GA signaling-related genes SlPIF1 and SlEXPs, with an opposite expression pattern between roots and shoots.

Three-dimensional kernel-based coda attenuation imaging of caldera structures controlling the 1982-84 Campi Flegrei unrest

Coda-wave attenuation imaging has risen as a state-of-the-art technique to depict volcanic structures using their dispersion effects. The 1982–84 seismic and deformation unrest at Campi Flegrei caldera (Italy) is a unique example of non-eruptive volcanic activity in a structured caldera. Here, we propose the first application of 3D coda-attenuation kernels to image caldera structures at multiple frequencies during unrest. Using sensitivity kernels is necessary to assess the effective resolution of coda imaging in highly heterogeneous volcanoes. The technique relies on the solution of Paasschens' equations in the framework of radiative transfer theory. The results map coda attenuation in the 3D space without need of pre-existent velocity models. The resolution and stability of the inversion solutions were examined by changing the damping parameters and outputting the corresponding images, inverting for different node spacings and performing checkerboard tests. These tests show that the resolution of the multiple-scattering model is much lower than that provided by a standard isotropic-scattering and/or single scattering technique. The best resolution in our model is obtained between depths of 1 km and 3 km in the centre of the model, between Pozzuoli town and Solfatara crater. The results are discussed at a frequency of 3 Hz, due to both longer coda durations and broader kernel illumination: in this frequency range, coda-based 3D imaging had so far failed to provide stable results. The interpretation is performed based on the extensive geological and geophysical knowledge of the caldera. High-attenuation anomalies below Solfatara and Monte Nuovo mark areas either saturated with water or enriched in molten rocks, feeding the respective fumarole fields. The flattening and horizontal elongation of these anomalies below 2 km depth is a manifestation of the blocking and spreading around of the rising hot magmatic fluids below a previously-inferred high-velocity, low-attenuation and highly-deforming caprock. This caprock is not uniform, likely due to the remnants of erupted structure. A SW-to-NE-trending low-attenuation and high-velocity anomaly deeps down to 3 km under Pozzuoli. We infer that the high seismicity in the region is a consequence of the stress sustained by the caprock from a 4-km-deep deformation source in 1983–84. On top of this source, high coda attenuation corresponds to high Vp/Vs ratios and high direct-wave attenuation. The region's characteristics are likely due to the accumulation of magmatic fluids above a magmatic sill.