Rectangular Cell Research Articles

Two-dimensional Stokes flows in porous medium composed of a large number of circular inclusions

A new approximate approach to solve the two-dimensional boundary-value problems for the Stokes flows in a porous medium composed of a set of circular inclusions is proposed. The idea of the approach, based on the boundary element method (BEM), lies in Fourier series representations of unknown functions on the surfaces of inclusions. It is shown that for small volume concentrations of inclusions, a good accuracy is achieved by taking into account only the first three terms in the Fourier decomposition. Simultaneously, the total number of unknowns, which is equal to the product of the number of inclusions and that of unknowns on every inclusion, is reduced dramatically in comparison with the traditional BEM. The approach is tested by investigating the flow around a circular cylinder in a rectangular periodic cell, the flow in a porous medium with a large number of uniformly or randomly located inclusions. To demonstrate the capacity of the approach, we have calculated the Stokes flows in the porous medium which is modelled by locating 5000 inclusions of two different radii. It is shown that the method can also be used to estimate the properties of the fluid flows in highly porous media formed by non-circular inclusions.

Flower, seed, and fruit development in three Tunisian species of Polygonum: Implications for their taxonomy and evolution ofdistylyin Polygonaceae.

Polygonum is the largest genus of Polygonaceae and 5 species are reported in Tunisia. In order to characterized flower, seed, and fruit development in Polygonum, flower and fruit of Polygonium equisetiforme (var. graecum and peyerinhoffi), P. aviculare and P. maritimum, collected from Tunisia, were examined. Flowers are composed of five oblong tepals. P. equisetiforme and P. aviculare have whitish-pink distylous flowers with dimorphism of style, filament and anther height, pollen diameter and stigma size. In contrast, P. maritimum shows white homostylous flowers. The floral vasculature showed that the tepals are inserted in one whorl and their traces arise independently in 3+2 manner. The eight stamens are arranged in a 5+3 manner and the staminal bundles arise independently in the two whorls. The epidermis and endothecium cells width were higher in P. maritimum and the lowest endothecium width was observed in P. aviculare. Polygonum aviculare and P. equisetiforme showed circular pollen with shallow colpi and trilobite pollen shape with deep colpi, while P. maritimum rarely showed shallow colpi. The ovule is anatropous with basal placentation in P. equisetiforme and P. aviculare and apical placentation in P. maritimum. The young seed coat was formed by an endotesta with thick-walled cells, a mesotesta and exotesta with thin-walled cells and a tegmen composed of radially elongated cells. The fruits of the studied species are trigonous with ovate-lanceolate shape. In P. aviculare, the exocarp is thicker compared to the two other species, in P. equisetiforme, the mature exocarp consists of smaller rectangular cells with narrow cavities, and in P. maritimum showed a thinner exocarpIn conclusion, P. equisetiforme and P. aviculare are a typically distylous species from the morphological point of view and we discussed the significance of heterostyly in Polygonaceae. From this first morpho-anatomical study of Polygonum species in North Africa, we can conclude mainly that there is no significant difference between P. equisetiforme var. graecum and var. peyerinhoffi supporting a taxonomic grouping of these two varieties.

Adsorption of sulfur on Si(111)

The adsorption of S on Si(111)- 7 × 7 has been investigated for different preparation schemes and parameters. S was supplied from an electrochemical Ag2S cell. For room temperature adsorption and subsequent annealing, no ordered S induced reconstruction can be observed with spot profile analysis low-energy electron diffraction (SPALEED). S deposition at temperatures above about 400 ∘C, however, leads to a well-ordered reconstruction. Judging from the LEED pattern, the same reconstruction was already observed by Metzner et al. [Surf. Sci. 377–379 (1997) 71–74] who identified it as 4 × 4 reconstruction. The upper temperature limit for the preparation of this superstructure depends on S flux, which is needed to compensate for desorption. Prolonged S exposure leads to surface roughening, as observed with SPALEED and scanning tunneling microscopy (STM), pointing to surface etching by S. From our SPALEED data, we can conclude that the observed reconstruction is not a 4 × 4 reconstruction, but a (2012) superstructure with a rectangular unit cell that exists in three rotational domains, as confirmed by STM. Different structural trial models have been assessed with density functional theory. Among these model structures, a configuration with dimers adsorbed on bridging sites, with a S coverage of 1 monolayer, is most likely, since it is energetically favorable and is in agreement with all experimental results.

Denitrifying Woodchip Bioreactor Leachate Tannic Acid and True Color: Lab and Field Studies

HighlightsOak leached more tannic acid, true color, and chemical oxygen demand (COD) than ash and mixed hardwood chips.The factors became similar (tannic acid, COD) or below stream levels (true color) after flushing.Eleven site-years of field bioreactor data showed decreasing tannic acid and true color over time.Post-startup tannic acid was lower in bioreactor outflow than in area streams.True color did not appear to be a reliable indicator of leachate tannic acid at low concentrations.Abstract. Woodchips have been a preferred denitrifying bioreactor medium to date, but concerns about potential harmful effects of tannins in the leachate have precluded the use of oak chips in many installations. A study was conducted to compare the suitability of oak (genus Quercus) woodchips as a denitrifying bioreactor medium relative to other types of woodchips, both in lab leachate tests and in the context of observed bioreactor leaching in the field. Assessment measures included the content of tannic acid and other compounds in the leachate, as well as leachate color, which can often be high during startup. An 84-day leaching test using rectangular bioreactor cells filled with either oak (Quercus rubra), ash (Fraxinus spp. L.), or a generic hardwood blend showed that oak initially leached higher concentrations of tannic acid, true color, and chemical oxygen demand (COD) than the other two media. The significant differences in leached concentrations among the three wood types were eliminated after a finite leaching period. Tannic acid and true color in 11 site-years of field bioreactor outflow data generally decreased over time, except following a dry period when one of the bioreactors received no drainage inflow for more than two months. The lab and field results indicated the capability of woodchip bioreactors to flush at least these two analytes to ambient stream levels. True color did not appear to be the best parameter for estimating the tannin content of woodchip leachate due to discrepancies at low concentrations. Mass normalized tannic acid leaching ranged from 0.03 to approximately 40 mg tannic acid g-1 woodchip across the lab and field assessments. Oak initially leached more tannic acid, color, and COD than the other wood types, but the eventual similarity among the wood types after flushing with a sufficient number of pore volumes meant that any potentially negative environmental impacts would likely be limited to the startup period or possibly after dry periods. Oak initially eluted higher mean total nitrogen (TN) concentrations than the other wood types, but the treatments were not significantly different by day 3, indicating that biological N removal was not significantly inhibited, even with high concentrations of tannic acid. Keywords: Chemical oxygen demand, Oak, Tannin, Water quality, Wood leachate.

Immiscible liquid-liquid displacement flows in a Hele-Shaw cell including shear thinning effects

We experimentally studied the viscous fingering instability considering a Newtonian oil displacing viscoelastic shear-thinning liquids and vice versa. The non-Newtonian liquids are aqueous solutions of polyacrylamide and xanthan gum, i.e., flexible and rigid polymers, respectively. A rectangular Hele-Shaw cell, connected by two plenum chambers, was developed to evaluate the displacement of a fixed volume. The experiment consists of analyzing the interface time evolution through a digital camera as a function of the geometric, dynamic, and rheological parameters. The displacement efficiency was determined through image processing in order to identify the formation of fingers or plugs. Unlike the Newtonian case, the transition does not occur when the viscosity ratio is roughly equal to one, but nevertheless, it was observed that the stability of the interface depends on the viscosity ratio. Specifically, more branches are observed at low viscosity ratios. Furthermore, a higher stability is observed when the Newtonian liquid displaces the shear thinning liquid, especially when the polymer is more rigid. When the Newtonian liquid is being displaced, elastic effects favor the displacing efficiency.

The band-gap structure of the spectrum in a periodic medium of masonry type

We consider the spectrum of a class of positive, second-order elliptic systems of partial differential equations defined in the plane \begin{document}$ \mathbb{R}^2 $\end{document} . The coefficients of the equation are assumed to have a special form, namely, they are doubly periodic and of high contrast. More precisely, the plane \begin{document}$ \mathbb{R}^2 $\end{document} is decomposed into an infinite union of the translates of the rectangular periodicity cell \begin{document}$ \Omega^0 $\end{document} , and this in turn is divided into two components, on each of which the coefficients have different, constant values. Moreover, the second component of \begin{document}$ \Omega^0 $\end{document} consist of a neighborhood of the boundary of the cell of the width \begin{document}$ h $\end{document} and thus has an area comparable to \begin{document}$ h $\end{document} , where \begin{document}$ h>0 $\end{document} is a small parameter. Using the methods of asymptotic analysis we study the position of the spectral bands as \begin{document}$ h \to 0 $\end{document} and in particular show that the spectrum has at least a given, arbitrarily large number of gaps, provided \begin{document}$ h $\end{document} is small enough.

Broadband Circularly Polarized Microstrip Patch Antenna Using Circular Artificial Ground Structure and Meandering Probe

To enhance axial ratio (AR) bandwidth, this research proposes a circularly polarized (CP) single-fed microstrip patch antenna using a circular artificial ground structure (AGS) and meandering probe. To achieve broader AR bandwidth, the circular AGS is populated with rectangular unit cells and partially cut unit cells along the circular contour, while the meandering probe is used to improve the impedance bandwidth. Simulations are performed and results compared with that of conventional rectangular-AGS antenna. The simulation results show that the circular-AGS antenna, given 62 mm circular ground plane, achieves broader impedance (5.12 - 9.00 GHz and 54%), AR (5.21 - 8.27 GHz and 45%) and gain bandwidths (3.85 - 7.00 GHz and 58.06%), in comparison with the rectangular-AGS antenna (4.50 - 7.45 GHz and 49%; 4.52 - 7.42 GHz and 21%; and 4.00 - 6.80 GHz and 51.58% for impedance, AR and gain bandwidths). The circular-AGS antenna is capable of converting linear polarization in the off-axial ratio band into circular polarization. To verify, a circular-AGS antenna prototype is fabricated and experiments undertaken. The experimental impedance, AR and gain bandwidths of the circular-AGS antenna are 47.82% (5.17 - 8.42 GHz), 43.81% (5.24 - 8.17 GHz) and 60.74% (3.75 - 7.00 GHz). The proposed circular-AGS antenna can achieve broader AR bandwidth and is thus ideal for broadband CP applications. The novelty of this research lies in the use of circular AGS to effectively enhance AR bandwidth, as opposed to rectangular AGS which is conventionally used in CP polarizers.

Conceptualization of the optimal design of a hydroxyl booster dry cell for enhancing efficiency of internal combustion engines

Current internal combustion engines (ICEs) are powered by fossil fuels which create the challenges of low combustion efficiency and the emission of greenhouse gases. This has negatively affected the environment, leading to global warming and climate change. Interim technologies can be implemented to reduce these effects whilst alternative technologies are being explored. This research aimed at selecting the most appropriate geometrical design of a hydroxyl booster dry cell, a device which operates on the principles of electrolysis to produce hydroxyl gas commonly referred to as Brown gas or HHO. When a voltage is applied to a body of water, it splits it into its base components, i.e. hydrogen and oxygen cold plasma, a mixture sometimes referred to as hydroxyl gas. The addition of hydroxyl gas into the combustion chamber of an ICE initiates a more complete combustion due to the explosive and diffusive nature of hydrogen accompanied by the cooling effect of water thus reducing potential for NOx formation. This leads to fuel savings, cost savings and reduced emissions. A rectangular hydroxyl booster dry cell was selected and designed, fabricated and tested for effectiveness. The HHO generator is later connected to the ICE system to check mainly on the positive contributions of this Brown’s gas as HHO is popularly known.

Research of Efficient Particle Tracking Method for DSMC

To advance recent research on super low-altitude satellites, it is necessary to investigate atmospheric drag, which is approximately 1000 times stronger in low- than in high-altitude satellites. The Direct Simulation Monte Carlo (DSMC) method is widely used to analyze this. However, the present DSMC method is extremely time consuming and costly due to high air density. In this study, we propose a new particle tracking method to reduce that cost by algebraic calculation using rectangular cell to create calculation cell. As a result, we reduced the cost of molecular movement up to 1/300.

Toward an interdisciplinary integration between multi-agents systems and multi-robots systems: a case study

Abstract Multi-Robot System (MRS) is composed of a group of robots that work cooperatively. However, Multi-Agent System (MAS) is computational systems consisting of a group of agents that interact with each other to solve a problem. The central difference between MRS and MAS is that in the first case, the agent is a robot, and in the second, it is a software. Analyzing the scientific literature, it is possible to notice that few studies address the integration between MAS and MRS. In order to achieve the interdisciplinary integration, the theoretical background of these areas must be considered in this paper, so that the integration can be applied using a case study of decentralized MRS. The objective of this MRS is to track and surround a stationary target. Also, it has been implemented and validated in the robot simulator called Virtual Robot Experimentation Platform (V-REP). In the validation of the proposed MRS, a scenario with three robots and a stationary target were defined. In the tracking task, the robot can detect the target whose position is not known a priori. When the detection occurs, the V-REP informs the target position to the robot because the environment is discretized into a grid of rectangular cells. After that, all the robots are directed to the target, and the surround task is realized. In this task, a mathematical model with direct communication between the robots was used to keep the robots equidistant therefrom and from each other.

Superconvergence of $$C^0$$-$$Q^k$$ Finite Element Method for Elliptic Equations with Approximated Coefficients

We prove that the superconvergence of $$C^0$$-$$Q^k$$ finite element method at the Gauss–Lobatto quadrature points still holds if variable coefficients in an elliptic problem are replaced by their piecewise $$Q^k$$ Lagrange interpolants at the Gauss–Lobatto points in each rectangular cell. In particular, a fourth order finite difference type scheme can be constructed using $$C^0$$-$$Q^2$$ finite element method with $$Q^2$$ approximated coefficients.

Group-IV monochalcogenide monolayers: Two-dimensional ferroelectrics with weak intralayer bonds and a phosphorenelike monolayer dissociation energy

We performed density functional theory calculations with self-consistent van der Waals corrected exchange-correlation (XC) functionals to capture the structure of black phosphorus and twelve monochalcogenide monolayers and find the following results: (a) The in-plane unit cell changes its area in going from the bulk to a monolayer. The change of in-plane distances implies that bonds weaker than covalent or ionic ones are at work within the monolayers themselves. This observation is relevant for the prediction of the critical temperature $T_c$. (b) There is a hierarchy of independent parameters that uniquely define a ground state ferroelectric unit cell (and square and rectangular paraelectric unit cells as well): only 5 optimizable parameters are needed to establish the unit cell vectors and the four basis vectors of the ferroelectric ground state unit cell, while square and rectangular paraelectric structures are defined by only 3 or 2 independent optimizable variables, respectively. (c) The reduced number of independent structural variables correlates with larger elastic energy barriers on a rectangular paraelectric unit cell when compared to the elastic energy barrier of a square paraelectric structure. This implies that $T_c$ obtained on a structure that keeps the lattice parameters fixed (for example, using an NVT ensemble) should be larger than the transition temperature on a structure that is allowed to change in-plane lattice vectors (for example, using the NPT ensemble). (d) The dissociation energy (bulk cleavage energy) of these materials is similar to the energy required to exfoliate graphite and MoS$_2$. (e) There exists a linear relation among the square paraelectric unit cell lattice parameter and the lattice parameters of the rectangular ferroelectric ground state unit cell. These results highlight the subtle atomistic structure of these novel 2D ferroelectrics.

Application of 2D temperature measurement to a coal-fired furnace using CT-TDLAS

The measurement of temperature and species concentration in combustion fields is very significant for the development of highly efficient combustion technologies for energy conservation and emission reduction. There are various measurement technologies, including contact and non-contact measurement. Tunable diode laser absorption spectroscopy (TDLAS) technology is a proven non-contact method for detection of the temperature and species concentration by absorption measurement. To enable two-dimensional (2D) representation of temperature and species concentration in combustion fields, the TDLAS technology is usually combined with computed tomography (CT). The latter is, however, considerably new in combustion research, especially in the solid fuel reaction environment. In this paper, a 32-path 2D CT-TDLAS system for temperature measurement in a pilot-scale coal-fired furnace was developed. The accuracy of the CT algorithm in the reconstruction of 2D temperature distributions in different laser-path arrangements was first analyzed using the sum of squared difference (SSD) and zero-mean normalized cross-correlation (ZNCC) by comparing it to the 2D temperature distribution of a full-scale coal-fired furnace simulated using computational fluid dynamics (CFD). The accuracy was improved by 32-path reconstruction. The study was then progressed to investigate its measurement accuracy in a simple CH4–air burner configuration with rounded and rectangular cells as well as sensitivity for flame shift detection, whereby the reconstructed temperature distribution was compared to the temperature measured using a thermocouple. It is verified that this CT reconstruction was feasible for various measurement areas, even if the center of the flame was shifted. Finally, a 32-path 2D CT-TDLAS system with a rectangular-structured cell was developed and applied for temperature measurement in a Tenaga Nasional Berhad (TNB) Research’s pilot-scale coal-fired furnace. The 2D temperature distribution in the coal-fired furnace was reconstructed according to the experimental results. The potential of the CT-TDLAS for online 2D temperature measurement for actual applications is demonstrated.

MORPHOLOGICAL, ANATOMICAL AND GEOGRAPHICAL DISTRIBUTION STUDIES OF SPECIES Horwoodia dicksoniae (Turrill) IN IRAQ

This research aims to study the morphological anatomical characteristics and geographical distribution of the species Horwoodia dicksoniae (Turrill) belong to Brassicaceae family in Iraq. The results were revealed the morphological characteristics of the root, stem, leaves, fruits and seeds, abaxial surface of the leaf characterized by covered with simple hairs. The fruits were circular in shape with wide wing and have one seed. The seeds were conical shape and pustular surface configuration. The anatomical characteristics of the root, stem, and leaf were studied and the cross-section of the root was characterized by thick periderm layer and cortex layer consisting primarily of parenchyma cells, stem cross section was characterized by thick layer of cuticle, as well as epidermis layer that followed the cuticle layer was double epidermis, but the layer of phloem is composed of rectangular cells and arranged in a continuous ring. Cross section of leaf was bifacial , leaf contains palisade cells in the form of a rectangle at the top surface of the leaf and irregular spongy cells at the low surface and distinguish the middle vein of the leaf as a circular shape. The epidermis was characterized by an Anisocytic type. The study of geographical distribution has been shown that the species is widespread in the desert region of Iraq.

Anisotropy in Polyurethane Pre-Insulated Pipes.

The polyurethane foam in district heating pre-insulated pipes has a critical role to play both as thermal insulation and as load bearing element, as it serves as bond between the medium pipe and the casing. Hence, knowledge on how the foam behaves under multiaxial stresses is of great importance for the design as well as for aging predictions of the network. It is known that cell shape anisotropy in polymeric foams leads to anisotropy in its mechanical properties. In this study, we evaluate and quantify the microstructural anisotropy of PU foam from pre-insulated pipes as well as its mechanical behaviour under compression in the three orthogonal directions. We cover rigid and flexible PU foam, batch and continuous manufacturing, and different pipe diameters. The results were compared with those predicted by available rectangular and Kelvin cell shape models. We have found that PU from pre-insulated pipes is orthotropic and present stronger anisotropy than that typically found in PU slabs. The traditional bonded pipes under consideration behaved in a similar way. However, when comparing the two flexible pipes in this study, despite no significant differences in cell shape anisotropy were found, a significantly different behaviour for the E modulus ratio was observed. This shows that while the manufacturing process exerts the main influence on cell shape anisotropy, to explain the difference in stiffness behaviour other factors need to be taken into consideration, such as cell size and cell size variability.

LoSI: Large scale location inference through FM signal integration and estimation

In this paper we present a large scale, passive positioning system that can be used for approximate localization in Global Positioning System (GPS) denied/spoofed environments. This system can be used for detecting GPS spoofing as well as for initial position estimation for input to other GPS free positioning and navigation systems like Terrain Contour Matching (TERCOM). Our Location inference through Frequency Modulation (FM) Signal Integration and estimation (LoSI) system is based on broadcast FM radio signals and uses Received Signal Strength Indicator (RSSI) obtained using a Software Defined Radio (SDR). The RSSI thus obtained is used for indexing into an estimated model of expected FM spectrum for the entire United States. We show that with the hardware for data acquisition, a single point resolution of around 3 miles and associated algorithms, we are capable of positioning with errors as low as a single pixel (more precisely around 0.12 mile). The algorithm uses a largescale model estimation phase that computes the expected FM spectrum in small rectangular cells (realized using geohashes) across the Contiguous United States (CONUS). We define and use Dominant Channel Descriptor (DCD) features, which can be used for positioning using time varying models. Finally we use an algorithm based on Euclidean nearest neighbors in the DCD feature space for position estimation. The system first runs a DCD feature detector on the observed spectrum and then solves a subset query formulation to find Inference Candidates (IC). Finally, it uses a simple Euclidean nearest neighbor search on the ICs to localize the observation. We report results on 1500 points across Florida using data and model estimates from 2015 and 2017. We also provide a Bayesian decision theoretic justification for the nearest neighbor search.

Influence of cell geometrical parameters on the mechanical properties of 3D integrally woven spacer sandwich composites

Woven spacer fabrics of rectangular (RECT), trapezoidal (TPZ) and triangular (TR) cell geometry with woven cross-links were produced and converted to composite forms. The cell height and width were varied in RECT structures, while in TPZ and TR structures, cell wall opening angle was changed keeping all other parameters almost constant. These composites were characterized for their out-of-plane compressive and flexural properties to compare their failure loads and energy absorbing capability. In RECT structures, specific compressive load decreased with increase in cell width (at similar cell height) and increase in cell height (at similar cell width), while the same in TPZ and TR structures increased with increase in cell wall opening angle. Compressive energy per unit volume was observed to be highest at particular cell width in RECT structures, while the same decreased with increase in the cell height of RECT structures. Similarly, energy/volume was higher for TR structure with 42.5° cell wall opening angle. For TPZ structures, energy/volume increased with increase in cell wall opening angle. Flexural properties followed the same trend as that of specific compressive load for these structures. Findings of this research can be used to engineer sandwich composites having woven cross-links with desired mechanical performance.

Variations in seed micromorphology and morphometry of native Indonesian Phalaenopsis and Paphiopedilum orchids

Abstract. Hariyanto S. 2019. Variations in seed micromorphology and morphometry of native Indonesian Phalaenopsis and Paphiopedilum orchid. Biodiversitas 20: 3559-3567. Seeds of ten taxa of the genera Phalaenopsis and Paphiopedilum orchids were studied using light and scanning electron microscopy (SEM). Qualitative characters (seed and embryo shape, seed and embryo colour, ornamentation of testa cell, testa cell wall shape) as well as quantitative data (seed and embryo length, seed and embryo width, seed and embryo volume, seed length/seed width, embryo length/embryo width, seed volume/embryo volume and air space) were analysed. Seeds of all studied taxa were fusiform in shape and had smooth testa surfaces. Phalaenopsis testa cells were elongated with cylindrical cell walls, while Paphiopedilum testa cells were polygonal with thin and flat rectangular cell walls. The shape of the embryos was generally ovoid in Phalaenopsis and prolate in Paphiopedilum. Seed colors ranged from brown to dark brown. Embryo colors varied from light yellow, yellowish-brown, dark brown, black and white. Based on our investigation, there are variations in seed and embryo length, seed and embryo width, seed and embryo volume as well as the percentage of the air space, both in Phalaenopsis and Paphiopedilum. In general, the values of seed volume, embryo volume and air space in Paphiopedilum are higher than in Phalaenopsis. Together, the results of the study indicate that morphological and morphometric features can serve to identify live forms and distinguish between species.

Design and study on the tailorable directional thermal expansion of dual-material planar metamaterial

Current studies on tailoring the coefficient of thermal expansion of metamaterials focused on either complex bending-dominated lattice or the stretching-dominated lattice which transforms the spaces of triangle and tetrahedron. This paper proposes a kind of dual-material rectangular cell of tailorable thermal expansion, which reduces the complexities of design, calculation, and manufacture of lattice materials. The theoretical derivation using the matrix displacement method is adopted to study the thermal expansion properties of rectangular cell in the direction of height, the analytical expressions of coefficient of thermal expansion and optimization model are used to design the sizes of rectangular cell, and experimental verification is carried out. It is found that the middle cell of lattice had the same thermal expansion law as that of the unit cell. The rectangular cells of negative coefficient of thermal expansion −7 ppm/℃, zero coefficient of thermal expansion, and large positive coefficient of thermal expansion 36.2 ppm/℃ in the direction of height were realized, respectively. The consistency of theory, simulation, and experiment verifies that rectangular lattice material made of two kinds of common materials with a different coefficient of thermal expansions can achieve the design of coefficient of thermal expansion in the direction of height by choosing different material distribution and geometric parameters.

Two dimensional joint inversion of direct current resistivity and radiomagnetotelluric data based on unstructured mesh

Using the unstructured mesh, a new two-dimensional joint inversion algorithm has been developed for Radiomagnetotelluric and Direct current resistivity data. The unstructured mesh is generated with triangular cells, whose vertical and lateral lengths increase towards the depths. The Finite Element Method (FEM) has been used in the forward modelling part of the developed joint inversion algorithm. In the previous studies, structured grid-based joint inversion algorithms have been developed using the Finite Difference Method (FDM). In the structured grid-based algorithms, when the mesh is being generated with rectangular cells, the vertical lengths of the cells get bigger towards the depths while the lateral lengths remain constant. With the structured mesh, the undulated surface topography cannot be represented well enough. Also, because of the incompatible aspect ratio of model cell sizes in deeper model sections, the resolution of the model parameters will get smaller and cannot be resolved well with the structured grids. Imaging of surface topography and underground resistivity structures by the new algorithm requires fewer elements than those using structured grids. Therefore, the developed algorithm is faster than traditional 2D inversion algorithms. Furthermore, the resolution of the deeper model parameters has been increased by using the definition of the unstructured grid. A regularized inversion scheme with a smoothness-constrained stabilizer has been employed to invert the data. First, we have tested the developed joint inversion algorithm using synthetic data simplified from archaeological and mine site scenario and the results have been compared with the conventional algorithms using structured grids. We have also tested our algorithm with the real data which were collected from mineral investigation site at approximately 10 km east of the Elbistan district of Kahramanmaraş province, in the west of the Taurus Mountains, Turkey. The results show that the developed joint inversion algorithm is a powerful tool to detect both resistive and conductive targets.