Porous Objects Research Articles

Powder bed fusion of solid and permeable Crofer 22 APU parts for applications in chemical process engineering

AbstractAdditive manufacturing of metals has attracted significant attention across various industries. However, its adoption in certain chemical and energy sectors remains constrained by the absence of optimized alloys tailored for high temperatures and corrosive environments. This study explores the laser-based powder bed fusion processing of Crofer 22 APU, a high-temperature, corrosion-resistant alloy ideal for applications such as methane steam reforming reactors, high-temperature fuel cells, and palladium membrane supports. Systematic optimization of laser parameters including laser power, hatch distance, point distance, and building angles was conducted for both dense and porous objects. Dense parts achieved a relative density of 0.9999 and surface roughness of Sa= 41.27±1.48 on a 45$$^\circ$$ ∘ overhang. Porous samples showed a porosity range of 28.655.5% and surface roughness Sa 22.2 $$\upmu$$ μ m to 45.9 $$\upmu$$ μ m as hatch distance increased from 0.12 mm to 0.16 mm. Additionally, an 8YSZ coating applied via screen printing demonstrated the impact of hatch distance and laser power on surface quality. The combination of additive manufacturing of Crofer 22 APU and screen printing of 8YSZ simplifies the preparation of metallic supports for Pd-based membranes, reducing fabrication time and cost by shortening the number of preparation steps. This technique offers a promising approach for scaling up membranes and membrane reactors.

Adsorption of Bichromate and Arsenate Anions by a Sorbent Based on Bentonite Clay Modified with Polyhydroxocations of Iron and Aluminum by the "Co-Precipitation" Method.

The physicochemical properties of natural bentonite and its sorbents were studied. It has been established the modification of natural bentonites using polyhydroxoxides of iron (III) (mod.1_Fe_5-c) and aluminum (III) (mod.1_Al_5-c) by the "co-precipitation" method led to changes in their chemical composition, structure, and sorption properties. It was shown that modified sorbents based on natural bentonite are finely porous (nanostructured) objects with a predominance of pores of 1.5-8.0 nm in size. The modification of bentonite with iron (III) and aluminum compounds by the "co-precipitation" method also leads to an increase in the sorption capacity of the obtained sorbents with respect to bichromate and arsenate anions. A kinetic analysis showed that, at the initial stage, the sorption process was controlled by an external diffusion factor, that is, the diffusion of the sorbent from the solution to the liquid film on the surface of the sorbent. The sorption process then began to proceed in a mixed diffusion mode when it limited both the external diffusion factor and the intra-diffusion factor (diffusion of the sorbent to the active centers through the system of pores and capillaries). To clarify the contribution of the chemical stage to the rate of adsorption of bichromate and arsenate anions by the sorbents under study, kinetic curves were processed using equations of chemical kinetics (pseudo-first-order, pseudo-second-order, and Elovich models). It was found that the adsorption of the studied anions by the modified sorbents based on natural bentonite was best described by a pseudo-second-order kinetic model. The high value of the correlation coefficient for the Elovich model (R2 > 0.9) allows us to conclude that there are structural disorders in the porous system of the studied sorbents, and their surfaces can be considered heterogeneous. Considering that heterogeneous processes occur on the surface of the sorbent, it is natural that all surface properties (structure, chemical composition of the surface layer, etc.) play an important role in anion adsorption.

Design of a soft gripper with negative-pressure actuated synthetic annulus microwedge adhesive

The automation and assembly lines of factories have faced the need for reliable handling of porous, fragile, and soft objects. Current soft grippers have difficulty robustly grasping flat, flexible surfaces without distorting them. This paper proposes a soft gripper based on annulus microwedge adhesive for grasping flat objects using negative pressure actuation mechanisms, which can achieve controllable adhesives to reliably grasp and easily release smooth flat objects. This is achieved through negative pressure actuation, which provides a centripetal load to the annular microwedge adhesives for strong attachment, by returning to normal pressure, the centripetal load is rapidly removed, allowing for easy detachment from the adhesive surface. Additionally, the relationship between the geometrical parameters of the deformation chamber and the contact area of annulus microwedges is investigated by using finite-element method models and experiments. The results show that the wall thickness is a key parameter in designing the deformation chamber. The results of the payload test have determined the geometrical and pressure parameters of the deformation chamber with the best adhesion performance. Finally, a demonstration shows that the gripper can handle various objects for potential applications, such as in clean environmental industries.

Three-dimensional flow around and through a porous screen

We investigate the three-dimensional (3-D) flow around and through a porous screen for various porosities at high Reynolds number $Re = {O}(10^4)$ . Historically, the study of this problem has been focused on two-dimensional cases and for screens spanning completely or partially a channel. Since many recent problems have involved a porous object in a 3-D free flow, we present a 3-D model initially based on Koo & James (J. Fluid Mech., vol. 60, 1973, pp. 513–538) and Steiros & Hultmark (J. Fluid Mech., vol. 853, 2018 pp. 1–11) for screens of arbitrary shapes. In addition, we include an empirical viscous correction factor accounting for viscous effects in the vicinity of the screen. We characterize experimentally the aerodynamic drag coefficient for a porous square screen composed of fibres, immersed in a laminar air flow with various solidities and different angles of attack. We test various fibre diameters to explore the effect of the space between the pores on the drag force. Using PIV and hot wire probe measurements, we visualize the flow around and through the screen, and in particular measure the proportion of fluid that is deviated around the screen. The predictions from the model for drag coefficient, flow velocities and streamlines are in good agreement with our experimental results. In particular, we show that local viscous effects are important: at the same solidity and with the same air flow, the drag coefficient and the flow deviations strongly depend on the Reynolds number based on the fibre diameter. The model, taking into account 3-D effects and the shape of the porous screen, and including an empirical viscous correction factor that is valid for fibrous screens may have many applications including the prediction of water collection efficiency for fog harvesters.

Fabrication of a stacked Archimedean spiral reactor with porous carbon walls using 3D-printed PLA as internal sacrificial template and carbonized whey powder as porous carbon matrix

This study introduces a method to create porous carbon structures with intricate internal voids. 3D-printed PLA acts as an internal sacrificial template, combined with carbonized whey powder as the porous carbon matrix. Sintering whey powder at 150°C yields solid pieces that, upon carbonization, result in highly porous carbon objects while maintaining the original mold shape. Temperature control ensures successful whey powder sintering before PLA melting. The use of PLA sacrificial templates, along with whey carbonization, allows for developing devices with finely tailored internal voids, as demonstrated through a double Archimedean spiral reactor with porous carbon walls.Graphical abstract

Development research of latent fingermarks based on aggregation-induced emission technique.

Fingerprints hold evidential value for individual identification; a sensitive, efficient, and convenient method for visualizing latent fingermarks (LFMs) is of great importance in the field of crime scene investigation. In this study, we proposed an aggregation-induced emission atomization technique (AIE-AT) to obtain high-quality fingermark images. Six volunteers made over 1566 fingerprint samples on 17 different objects. The quality of fingermark development was evaluated using grayscale analysis for quantitative assessment, combining the fluency of fingermark ridges and the degree of level 2 and level 3 features. Both qualitative and quantitative methods were employed to explore the effectiveness of AIE molecule C27H19N3SO in developing fingermarks, its applicability to objects, and its individual selectivity. Additionally, the stability of the AIE molecule was examined. Comparative experimental results demonstrated the high stability of the AIE molecule, making it suitable for long-term preservation. The grayscale ratio of the ridges and furrows was at least 2, with high brightness contrast, the level 2 and level 3 features were clearly observable. The AIE-AT proved to be effective for developing fingermarks on nonporous, porous, and semiporous objects. It exhibited low selectivity on suspects who leave fingermarks and showed better development effects on challenging objects, as well as efficient extraction capability for insitu fingermarks. In summary, AIE-AT can efficiently develop latent fingermarks on common objects and even challenging ones. It locates the latent fingermarks for further accurate extraction of touch exfoliated cells insitu, providing technical support for the visualization of fingermarks and the localization for extraction of touch DNA.

Eu-MOF-Based Fluorescent Ratiometric Sensor by Detecting 3,4,5-Trihydroxybenzoic for Fingerprint Visualization on Porous Objects

Latent fingerprints (LFPs) at the crime scene are served as important clues to locate the trajectory of criminal behavior and portray the characteristics of the suspect. Therefore, visualizing LFPs is of considerable significance. In this work, the europium metal-organic framework (Eu-MOF) sensor was successfully constructed for sensitive detection of gallic acid (3,4,5-trihydroxybenzoic acid, GA) and visualization of the sweat LFPs. The boric-acid-modified Eu-MOF was prepared by using the simple one-pot solvothermal method using Eu as the metal ion center and 3,5-dicarboxybenzeneboronic acid (BBDC) as the organic ligand. The sensor showed desirable photoluminescent performance through the chelating of BBDC with Eu3+. The sensor exhibited the satisfactory linear relationship to GA in the range of 1 nM to 20 nM with a low detection limit of 0.34 nM under the optimized conditions. The prepared sensor with ideal selectivity to GA was successfully applied for visualizing LFPs on porous substrates with the high contrast and superior stability. Given the good performance of the sensor, all fingerprint images obtained from 1 200 samples presented clear friction ridges and met the identification criteria. Notably, the sensor had less impact on the subsequent deoxyribonucleic acid (DNA) detection, displaying a promising perspective for applications in extracting physical evidence of site investigation.

Comparative Study of the Physico-Chemical Properties of Sorbents Based on Natural Bentonites Modified with Iron (III) and Aluminium (III) Polyhydroxocations

A comparative study of the physicochemical properties of natural bentonite clays of Pogodayevo (Republic of Kazakhstan, mod. 1) and Dash-Salakhli (Republic of Azerbaijan, mod. 2) deposits and modification of the bentonite clay with polyhydroxocations of iron (III) and aluminium (III). The amount of bentonite in the concentration of iron (aluminum) was 5 mmol Me3+/g. It was established that the modification of natural bentonites using polyhydroxocations of iron (III) (mod. 1_Fe_5-c, mod. 2_Fe_5-c) and aluminum (III) (mod. 1_Al_5-c, mod. 2_Al_5-c) by the method of “co-precipitation” leads to a change in their chemical composition, structural and sorption properties. The results showed that hydroxy-aluminum cations ([Al3O4(OH)24(H2O)12]7+) and poly-hydroxyl-Fe or polyoxo-Fe were intercalated into clay layers, which led to an increase in the values of d001 and specific surface areas compared to those of the original bentonite, from 37 to 120 m2/g for the Pogodaevo bentonite and from 51 to 172 m2/g respectively, for bentonite from the Dash-Salakhli deposit. It is shown that modified sorbents based on natural bentonite are finely porous objects with a predominance of pores of 1.5–8.0 nm in size. As a result, there is a significant increase in the specific surface area of sorbents. Modification of bentonite with polyhydroxocations of iron (III) and aluminum (III) by the “co-precipitation” method also leads to an increase in the sorption capacity of the sorbents obtained with respect to nickel (II) cations. Modified bentonites were used for the adsorption of Ni (II) ions from the model solution. Ni (II) was absorbed in a neutral pH solution. The study of equilibrium adsorption showed that the data are in good agreement with the Langmuir isotherm model. The maximum adsorption capacity of the Ni (II) obtained from the Langmuir equation was 25.0 mg/g (mod. 1_Al_5-c), 18.2 mg/g (mod. 2_Al_5-c) for Al-bentonite and 16.7 mg/g (mod. 1_Fe_5-c), 10.1 (mod. 2_Fe_5-c) for Fe-bentonite. The kinetics of adsorption is considered. The high content of Al-OH anion exchange centers in them determines the higher sorption activity of Al-modified bentonites.

Visualizing Fingerprints on Porous Objects by an Optical Sensor Minimally Destructive to DNA Based on Aggregation‐Induced Emission

AbstractDevelopment of latent fingerprints (LFPs) at the scene played the important role in forensic investigations by reconstructing crime trajectory and individualizing suspect. In this work, the optical sensor named TPE‐LL with aggregation‐induced emission property was constructed and used in LFPs visualization. The sensor exhibited a satisfactory linear relationship to tryptophan (Trp) in the range of 1–20 nM with the low detection limit of 0.15 nM. The samples were collected from 60 volunteers, with a total of 7200 impressed samples and 160 natural samples. Significantly, the high‐resolution fingerprints images with high fidelity and contrast containing pore features were obtained from impressed samples left on porous object for 15 days. Meanwhile, the relative complete STR typing profiles of deposited DNA were obtained and the identification rate of DNA after the develop process was 76.5 %, suggesting that the method was low destructive to DNA. The results indicated that the sensor provided promising perspectives on solving the current technical problems in the field of forensic science and technology

Continuous printing of bone-inspired hierarchical porous objects using video projection-based stereolithography

Bone-inspired porous structures have attracted intense attention in biomedical and mechanical applications due to their unique combination of strength, toughness, and low weight. Although layer-by-layer-based additive manufacturing techniques can build structures with high geometric complexity, it remains challenging to fabricate porous objects with gradient porosity and pore size ranging from nano- to micro-scale. This research investigates the video projection-based stereolithography (VP-SL) process, which is a continuous 3D printing process, also known as Continuous Liquid Interface Production (CLIP), for fabricating hierarchical porous structures with nano-, micro- and macro-scale pores and surface features. This work tested the hypothesis that tuning the printing speed during the VP-SL process can generate an imbalance between curing and resin recoating, resulting in pores in cured polymer. First, the VP-SL process, setup, and the mechanisms of forming micropores and nanowrinkles were introduced. Then, the printing range of the VP-SL process was characterized using curing depth experiments. To validate the efficiency and feasibility of the proposed approach, various three-dimensional hierarchical structures were fabricated with homogeneous and gradient porosity, and the effect of porosity distribution on mechanical properties was studied. Test cases were printed and characterized to validate the feasibility and efficiency of the proposed approach. The results demonstrated the capability of the VP-SL process and its potential in the production of gradient porous objects for various applications, such as scaffolds for custom bone implants.

Gripping Device for Textile Materials

Gripping and manipulating non-rigid and porous objects is an important challenge for manufacturing. Now there are many problems in handling textile materials from a stack or oriented in space. Therefore, the paper presents the design of an improved Bernoulli gripping device with an anti-vibration insert. The inventive gripper structure allows gripping and manipulating textile materials and partially eliminates the shortcomings present in the classic design of the gripper. A technique for theoretical modeling of a gripping device for textile materials has been developed. This made it possible to determine the rational parameters of the gripping device in terms of maximum attraction. Experimental study of power characteristics of gripping device for textile materials has been carried out. The choice of the thickness of the anti-vibration insert made by the 3D printing method is justified. The advantages of the design include enabling gripping of textile materials of manipulation at different position, orientation and from a longer distance. Influence of supply pressure on the beginning of object vibration is analyzed. Parameters of anti-vibration insert are defined for the operation of gripper without object vibration. <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Note to Practitioners</i> —This paper was motivated by the problem of gripping and holding textile materials during manufacturing. There are many approaches to gripping a piece of textile material that have high energy consumption or can damage it. This paper proposes the design of the gripper that uses compressed air to lift the textile material at different orientations. Using the proposed theoretical model, one can calculate the lifting force of the gripper at different porosity of the material. Knowing the mass of the material, one can determine which parameters to choose for the gripper based on experimental results. Positive results are highlighted in the capture of porous objects without the loss of force at different orientations. Negative aspects are shown in the formation of vibration of the material when reaching a certain pressure level in the gripper. Future research plans to improve the design of the gripper by modeling the gripper using the finite element method and proposing effective methods of manipulating textile materials.

Finite element modeling of grasping porous materials in robotics cells

AbstractHandling and manipulating flexible porous objects is one of the main challenges in robotics for household and industrial tasks. Improving the design of grippers for flexible objects of manipulation is an important stage in the development of this topic. This article proposes a method of modeling a gripper for porous objects using the finite element method. It identifies the main parameters of the model that will affect the grasping force and the permeability of porous objects. The power characteristics of the obtained gripper model for different supply pressures, with varying porosity of the manipulated objects, are determined. The obtained characteristics are then used to find the correspondence of channel length for three textile materials with different permeable properties. An experimental study of the lifting force is conducted, and a comparison is made with the obtained modeling data for the presented samples. Additionally, using the obtained simulation data, an analysis of the pressure distribution on the surface of the porous object of manipulation is performed. As a result, it is found that the gripping device must use a design with elements to stabilize the distribution of pressure in its chamber, which will increase the stability of the gripping process.

A Porous Nanostructured ZnO Layer for Ultraviolet Sensing with Quartz Crystal Microbalance Technique.

Porous films of metals and metal oxides have gained growing attention as potential materials for use in applications that require large, specific surface areas, such as sensors, supercapacitors, and batteries. In this study, a "black-metal"-like porous Zn-ZnO composite layer was grown by room temperature co-sputtering of Zn metal and ZnO:Ga (3 at/%) ceramic targets. Following deposition, a porous ZnO layer was obtained by a subsequent thermal annealing process at 400 °C in air. The morphology and structural properties of the obtained porous layered objects were analyzed. The porosity and chemical characteristics of the nanostructured ZnO layer obtained with the method herein described make it suitable to be used as a sensitivity-enhancing active layered element in quartz crystal microbalance (QCM)-based ultraviolet (UV) sensors. The prepared resonant ZnO/QCM sensors under UV radiation exhibited maximum shift up to 35 Hz for several "on-off" UV cycles, excellent response, and recovery times of 11 and 12 s, respectively.

Chemically Customizing Mechanical Properties and Optical Transparency in Underwater Superoleophobic Coating

AbstractThe inherent ability of bio‐inspired underwater superoleophobicity to prevent oil/oily fouling underwater makes it appropriate for a wide range of applications related to environmental remediation, bio‐adhesion, microfluidics, chemical sensing, etc.; however, the co‐association of mechanical durability and optical transparency is essential for realistic performance. While the design of mechanically durable and absolutely optically transparent underwater superoleophobic coating remains challenging, here, a covalently cross‐linked and chemically reactive sol‐gel conversion process is introduced through 1,4‐conjugate addition reaction to achieve a substrate‐independent and tolerant coating for orthogonally modulating the underwater oil wettability, optical transparency, and even mechanical properties of highly deformable porous and fibrous substrates. The post‐modification of residual chemical reactivity in the prepared coating allows to embed underwater superoleophobicity, and the β‐amino‐ester‐cross‐links improve the mechanical property of selected deformable substrates. Moreover, it displayed unperturbed performance even after prolonged (30 days) exposures in practically relevant chemically harsh aquatic conditions—including extremes of pH, artificial seawater, surfactant contaminated water, etc. The approach is successfully applied to coat various substrates—including porous, fibrous, and planar objects, and it would be useful in protecting various relevant marine infrastructures from oil/oily fouling, and various other potential applications.

Comparative study on different cooling techniques for photovoltaic thermal management: Hollow fins, wavy channel and insertion of porous object with hybrid nanofluids

The present work considers performance of different cooling methods applicable to photovoltaic (PV) panels. Hollow fins and two different channel cooling systems are considered. Flat and hollow fins types are used while cooling channels with wavy wall and with porous layer insert are compared. Effects of different fin numbers (between 2 and 16), hollow fin radius (between 0.8h and 3.2h, h-panel height), Reynolds number (between 100 and 500), wavy channel amplitude (between 0.01H and 0.5H, H-channel height), porous insert permeability (Darcy number between 10−6 and 10−1), porous layer size (between 0.1L and 0.7L, L-channel length) and nanoparticle volume fraction (between 0 and 0.02) on the cooling performance are numerically assessed. When nanofluid is used in the cooling channels, additional improvements in the cooling performance are obtained while temperature drop of 2.5 °C is achieved at the highest loading. When different cooling systems are compared, channel cooling with porous layer and wavy walls provide the highest cooling performance followed by hollow fin and flat fin systems while 37.6 °C , 37 °C, 33.6 °C and 29 °C temperature drops are obtained as compared to reference panel case without cooling system. When compared to flat fins, hollow fins perform better and additional temperature drop of 8.5 °C can be obtained by using 16 number of fins. It also provides a lightweight design as less material is used. Artificial neural networks are successfully used for performance estimation of wavy cooling channel system with 15 neurons in the hidden layer. The outcomes of this work is useful in further optimization and system development of PV cooling technologies as the need for thermal management in renewable energy sources is increasing due to the energy cost and environmental side concerns.

An assessment of the scalings for the streamwise evolution of turbulent quantities in wakes produced by porous objects

Experimental results are presented for the evolution of three turbulent quantities in the wake of a porous object, analogous to a wind-turbine wake. These are the mean velocity deficit, the turbulence intensity, and the characteristic wake width. It is noted that characteristic wake widths can be defined both in terms of the mean velocity deficit profile and the profile of turbulence intensity. Both definitions of wake width are observed to grow linearly, although not at the same rate, with that defined by turbulence intensity growing more rapidly than velocity deficit. The streamwise scaling of both wake width, and velocity deficit is found to conform to a non-equilibrium dissipation scaling in which the dissipation rate within the wake is out of equilibrium with the inter-scale energy flux within the mean cascade of turbulent kinetic energy. The cumulative effect of turbulence intensity produced by N upstream porous objects is also considered. It is shown that when the object spacing is sufficiently large that the wake-added turbulence decays substantially only consideration of the most immediately upstream wake is important. Contrastingly, when the spacing between adjacent objects is small then summing the contributions from all upstream wakes in the array is necessary.

Thermal performance assessment by using a wavy porous obstacle in a circular vented cavity under non-uniform magnetic field during forced convection of hybrid nanofluids

In this study, effects of using a wavy porous object on the thermal performance improvement in circular vented cavity are numerically assessed during hybrid nanofluid convection under non-uniform magnetic field. Numerical analysis is conducted for varying values of Reynolds number (Re, between 200 and 1000), Hartmann number (Ha between 0 and 50), magnetic field inclination (γ between 0 and 90) while Darcy number is taken between and . The amplitude is considered between 0 and 0.5 while wave number of the corrugated porous object is taken between 2 and 16. Significant impacts of the porous object parameters and permeability on the flow pattern distribution and thermal performance improvements are obtained. The magnetic field improves the heat transfer for the lower permeability object case at Ha = 10 while the average Nusselt number (Nu) is reduced for the case with higher permeability object case. Average Nu number improvement up to 33.5 is obtained with the imposed non-uniform magnetic field effects. Average Nu variations of 27.3 and 15 are obtained when the corrugation wave number and amplitude are varied. The Constrained Optimization BY Linear Approximations optimization is used to achieve the highest thermal performance of the configurations.

CFD Study of MHD and Elastic Wall Effects on the Nanofluid Convection Inside a Ventilated Cavity Including Perforated Porous Object

Cost-effective, lightweight design alternatives for the thermal management of heat transfer equipment are required. In this study, porous plate and perforated-porous plates are used for nanoliquid convection control in a flexible-walled vented cavity system under uniform magnetic field effects. The finite element technique is employed with the arbitrary Lagrangian–Eulerian (ALE) method. The numerical study is performed for different values of Reynolds number (200≤Re≤1000), Hartmann number (0≤Ha≤50), Cauchy number (10−8≤Ca≤10−4) and Darcy number (10−6≤Da≤0.1). At Re = 600, the average Nusselt number (Nu) is 6.3% higher by using a perforated porous plate in a cavity when compared to a cavity without a plate, and it is 11.2% lower at Re = 1000. At the highest magnetic field strength, increment amounts of Nu are in the range of 25.4–29.6% by considering the usage of plates. An elastic inclined wall provides higher Nu, while thermal performance improvements in the range of 3.6–6% are achieved when varying the elastic modulus of the wall. When using a perforated porous plate and increasing its permeability, 22.8% increments of average Nu are obtained. A vented cavity without a plate and elastic wall provides the highest thermal performance in the absence of a magnetic field, while using a porous plate with an elastic wall results in higher Nu when a magnetic field is used.

Enhanced Branch Simulation to Improve RAPID in Optical Region Using RAMI Scenes

To improve the simulation accuracy of vegetation canopy reflectance in optical bands, the Radiosity Applicable to Porous IndiviDual objects (RAPID) model has been upgraded to better deal with branches in the latest RAPID4. Previous versions of RAPID (RAPID1 and RAPID3) neglected branches in porous objects in optical bands, while RAPID2 emphasized them in microwave bands. This inconsistency needed to be addressed to establish a unified radiosity-based simulation framework. By incorporating branches in RAPID4, we have improved several aspects of the model, including the random dynamic projection process, the equivalent reflectance or transmittance, the single scattering estimation, the multiple scattering solution, and the bidirectional reflectance factor (BRF) calculation. Three-dimensional trees from the fifth RAdiation transfer Model Intercomparison (RAMI-V) have been used to test the contribution of branches on BRF. Comparisons with a ray-tracing-based LESS model (the LargE-Scale remote sensing data and image Simulation framework) on RAMI-V scenes show a general agreement on BRF ( R 2 ≥ 0.96 and root mean square error ranging from 0.014 to 0.054). The major biases occur in a realistic scene (i.e., HET51_WWO_TLS) created from terrestrial laser scanning data. Sensitivity analysis has been conducted to show the branch contribution on BRF in optical domain. Without considering dense branches, the BRF error can exceed 0.1.

Абляция мелких метеорных тел: сравнение модели сплошного и пористого тела

An ablation model is used to describe the interaction of small meteoroids with the Earth’s atmosphere. In this model, the mass loss of a meteoroid is determined using the saturated vapor pressure of the assumed meteoroid substance. The meteoroid is considered in two modifications as a solid and a porous object. An automated method for estimating the parameters of meteoroids (mass, size, and density) from light curves is developed based on the model of small meteor body ablation, which has been used to estimate the parameters of the Perseid meteors with a brightness of -2m to +2m. The effect of the dependence for saturated vapor pressure and the residual on the parameters of the meteoric body is analyzed. It is shown that for the same meteor, the use of different dependences for pressure or different residuals leads to the dispersion of the meteor mass estimate of not more than 10-15% of the average value, and for the meteor size not more than 35-40%. The difference between the maximum and minimum density estimates can be up to five times. The selected dependence for the saturation vapor pressure strongly affects the shape of the light curve, the quality of its approximation, and the density estimate. The average porosity for all meteoroids is 86±5%, which is close to the values for IDP. The density of meteoroids is determined with a large error. The selected model better describes meteoroids with the degree of skewness of the light curve in the range of 0.4 - 0.5. The use of the porous body model has little effect on the mass estimate, while the density estimates increase by up to 2 times.