Maximum Spacing Research Articles

Geoelectrical Exploration of Groundwater by Using Vertical Electrical Sounding Technique at Wadi Morra, South Sinai, Egypt

Wadi Morra area is one of the most important areas targeted by the government for sustainable development. This development depends mainly on groundwater occurrences. This research aims to explore groundwater in this region, which depends on groundwater for its needs. To achieve this aim, the geoelectrical resistivity method was used, represented by Schlumberger Vertical Electrical Soundings (VESs). Seventeen VESs have been carried out with a maximum half current electrode spacing (AB/2) of 700m. The measured VESs are interpreted qualitatively and quantitatively to construct a geoelectrical model. To detect the water-bearing layers and their extensions, three geoelectric cross-sections in addition to a one-panel diagram were constructed using all the available data. Also, both true resistivity and isopach contour maps of waterbearing layers were created based on these data. The interpretation results indicate that there are five geoelectric layers (A, B, C, D, and E), two of them (C and D) are water-bearing layers. The first water-bearing layer is layer C, which represents the Nubian sandstone aquifer, and the second layer is layer D, which represents the fractured basement aquifer. These two aquifers were observed along the northern part of the Saint Catherine - Nuweiba road that dissects the Wadi Morra basin, while it is absent at the southern part of this road. It is due to the presence of a few faults. According to groundwater occurrences, the study area was divided into two zones. The first zone is zone (A) where the groundwater is present, either in the Nubian sandstone aquifer or in the fractured basement aquifer and the second zone is zone (B) where there is no groundwater at all due to the presence of basement rocks at a few depths. This research also recommends that the best places for drilling productive wells be at zone A.

Interactive Effects in Two-Droplets Combustion of RP-3 Kerosene under Sub-Atmospheric Pressure

To improve our understanding of the interactive effects in combustion of binary multicomponent fuel droplets at sub-atmospheric pressure, combustion experiments were conducted on two fibre-supported RP-3 kerosene droplets at pressures from 0.2 to 1.0 bar. The burning life of the interactive droplets was recorded by a high-speed camera and a mirrorless camera. The results showed that the flame propagation time from burning droplet to unburned droplet was proportional to the normalised spacing distance between droplets and the ambient pressure. Meanwhile, the maximum normalised spacing distance from which the left droplet can be ignited has been investigated under different ambient pressure. The burning rate was evaluated and found to have the same trend as the single droplet combustion, which decreased with the reduction in the pressure. For every experiment, the interactive coefficient was less than one owing to the oxygen competition, except for the experiment at L/D0 = 2.5 and P = 1.0 bar. During the interactive combustion, puffing and microexplosion were found to have a significant impact on secondary atomization, ignition and extinction.

Maximum Space around the Typewriter: Yvonne Vera and the Craft of Writing

The late Zimbabwean author Yvonne Vera puts material culture to use throughout her published fiction. Her engagement with the physical stuff that enters her writing reflects less the current wave of political craft scholarship and perhaps more an opportunity to work with the beauty of details provided both by the horrific and the everyday. This article argues that the descriptions Yvonne Vera offers us of her own writing process shed light on her work as a practitioner – a practitioner of the craft of writing – an emphasis often overlooked in studies more national or political in focus. Overall, the article is interested in acknowledging the less predictable nature of the creative process, which in Vera's case sought inspiration through attention to material culture, a process often described by Vera as an embodied, consuming search.

CALCULATION METHOD FOR CRACK WIDTH OF STEEL FIBER-REINFORCED LIGHTWEIGHT AGGREGATE CONCRETE BEAMS REINFORCED WITH FRP BARS CONSIDERING BOND-SLIP BEHAVIOR

Regarding the crack development of concrete beams reinforced with fiber-reinforced polymer (FRP) bars as a process wherein the FRP bars are pulled out from concrete on both sides, a differential equation of crack width of lightweight aggregate concrete beams reinforced with FRP bars considering bond-slip behavior was established. According to the crack width limits provided by the design codes, the upper limit of slip was reasonably determined and constitutive models for bond-slip relationship between FRP bars and steel fiber reinforced-lightweight aggregate concrete in ‘low slip’ stage which were suitable to the service stage of the beams were proposed and introduced. The maximum crack spacing, lmax, amplification factor of crack width, h2/h1, and residual stress of fiber reinforced-concrete in cracked sections, σfib, were specified. On this basis, a crack width model of steel fiber reinforced-lightweight aggregate concrete beams reinforced with FRP bars was proposed using iterative algorithm and its accuracy was evaluated based on measured data of maximum crack width in service stage. It is shown that within crack width limit of 0.5 mm, the proposed model generates accurate maximum crack width predictions for steel fiber-reinforced lightweight aggregate concrete beams reinforced with FRP bars.

Hydrogeophysical characterization of aquifers in Upper Denkyira East and West Districts, Ghana

Hydrogeophysical assessment of aquifers in the Upper Denkyira East and West Districts of Ghana has been carried out for groundwater potential and protective capacity of the overburden rocks determination. The data for the study were obtained from the Regional office of Community Water and Sanitation Agency (CWSA), Cape Coast. A total of thirty-seven VES probed using a Schlumberger array with maximum current electrode spacing (AB/2) of 100 m at each point using the Abeam Terameter was used. The data were interpreted using the partial curve matching and WINRESIST computer iteration program techniques. The thickness and resistivities of the various overburden layers, basement resistivity, reflection coefficient and longitudinal conductance were used for the assessment of the groundwater potential and the protective capability of the overburden layers. The study revealed three-to-six layers with an average of four (4) layers including laterite (0.34–3.57 m); clay (0.64–8.84 m); sandy-clay (0.67–27.09 m) and slightly-to-highly weathered bedrock which includes phyllites and granite (3.09–86.89 m) that show high level of heterogeneity of electrical resistivity of the geologic materials within the study area. The weathered layers serve as the aquiferous zones. About 21.6%, 62.2%, 2.7% and 13.5% showed high, medium, low and very low potential for groundwater, respectively, with higher groundwater potentials at the western and south-eastern corner of the study area underlain by the Birimian and Tarkwaian formations, respectively, indicating that the two formations have similar groundwater potentials in the study area. The lowest groundwater potential was observed at the point underlain by the granitic intrusion. The assessment of the protective capacity of the aquifer showed very good (5%), good (27%), moderate (19%), weak (22%) and poor (27%) indicating that the study area is overlain mostly by materials of different protective capacities. This study presents information on the aquifer protective capacity evaluation by using geophysical technique and it has revealed that the Birimian formation has a good aquifer protective capacity than the Tarkwaian formation and has also confirmed the effectiveness of using geophysical techniques in ground investigation.

Approximations of density matrices in N-electron valence state second-order perturbation theory (NEVPT2). I. Revisiting the NEVPT2 construction.

Over the last decade, the second-order N-electron valence state perturbation theory (NEVPT2) has developed into a widely used multireference perturbation method. To apply NEVPT2 to systems with large active spaces, the computational bottleneck is the construction of the fourth-order reduced density matrix. Both its generation and storage become quickly problematic beyond the usual maximum active space of about 15 active orbitals. To reduce the computational cost of handling fourth-order density matrices, the cumulant approximation (CU) has been proposed in several studies. A more conventional strategy to address the higher-order density matrices is the pre-screening approximation (PS), which is the default one in the ORCA program package since 2010. In the present work, the performance of the CU, PS, and extended PS (EPS) approximations for the fourth-order density matrices is compared. Following a pedagogical introduction to NEVPT2, contraction schemes, as well as the approximations to density matrices, and the intruder state problem are discussed. The CU approximation, while potentially leading to large computational savings, virtually always leads to intruder states. With the PS approximation, the computational savings are more modest. However, in conjunction with conservative cutoffs, it produces stable results. The EPS approximation to the fourth-order density matrices can reproduce very accurate NEVPT2 results without any intruder states. However, its computational cost is not much lower than that of the canonical algorithm. Moreover, we found that a good indicator of intrude states problems in any approximation to high order density matrices is the eigenspectra of the Koopmans matrices.

Optimal hydropower generation of Maithon multi‐purpose reservoir system

AbstractThe present study focuses on optimizing the hydropower generation capacity of a multi‐purpose reservoir system considering various constraints, including reservoir water mass balance, minimization of sediment, maximum and minimum reservoir water storage, maximum and minimum reservoir water releases, reservoir water drawdown levels, reservoir overflows, maximum flood zone space, and maximum and minimum storage constraints under 50%, 70% and 90% dependable inflow conditions The focus is the Maithon multi‐purpose reservoir system located at Maithon, a distance of 40.2 km from Dhanbad, the coal capital of India, in the State of Jharkhand. The study results indicate the derived policy is capable of producing maximum annual hydropower of 146,519.48 MWh/year for a 50% dependable inflow condition, 105,512.02 MWh/year for a 70% dependable inflow condition and 58,924.38 MWh/year for a 90% dependable inflow condition, compared to the existing hydropower generation of 129,428.4 MWh/year (average of last 10 years). A trade‐off between reservoir release water releases, mostly for meeting irrigation water needs and maximizing energy generation, was determined for use by various stakeholders and managers of reservoir operations.

Injection of positrons into a dense electron cloud in a magnetic dipole trap

The creation of an electron space charge in a dipole magnetic trap and the subsequent injection of positrons have been experimentally demonstrated. Positrons (5 eV) were magnetically guided from their source and injected into the trapping field generated by a permanent magnet (0.6 T at the poles) using a cross field E × B drift, requiring tailored electrostatic and magnetic fields. The electron cloud is created by thermionic emission from a tungsten filament. The maximum space charge potential of the electron cloud reaches −42 V, which is consistent with an average electron density of (4±2)×1012 m−3 and a Debye length of (2±1) cm. We demonstrate that the presence of this space potential does not hamper efficient positron injection. Understanding the effects of the negative space charge on the injection and confinement of positrons represents an important intermediate step toward the production of a confined electron–positron pair plasma.

Enhanced Anti-Corrosion Performances of Epoxy Resin Using the Addition of Sodium Dodecylbenzene Sulfonate-Modified Graphene

The improvement of anti-corrosive property of epoxy resin is significant for the development of coatings to avoid metal corrosion and thus to reduce the economic loss in many industries. The superior properties of graphene, a two-dimensional material, make it possibly suitable to fulfill this task. However, this is hindered by the easy agglomeration of graphene layers in solvents. In the present work, we report the modification and stabilization of graphene in water using sodium dodecylbenzene sulfonate (SDBS) and the enhancement of the anti-corrosive properties of epoxy resin by mixing such SDBS-modified graphene layers. The influence of the dosage of SDBS on the modification effect of graphene was studied in detail and an optimized dosage, i.e., 50 mg SDBS for 10 mg graphene, was obtained. The SDBS modification could effectively reduce graphene thickness, and the minimum thickness of the modified graphene was 3.50 nm. The modified graphene had increased layer spacing, and the maximum layer spacing was 0.426 nm. When the modified graphene was added into the epoxy resin, the electrochemical impedance modulus value evidently increased compared to pure epoxy resin and those incorporated by pure graphene, indicating that the anti-corrosion performance was significantly improved. These results clarified that SDBS could effectively modify graphene and the SDBS-modified graphene could subsequently largely improve the anti-corrosive property of epoxy resin, which is of significance for the anti-corrosive coatings.

Controlling martensitic transformation characteristics in defect-free NiTi shape memory alloys fabricated using laser powder bed fusion and a process optimization framework

Laser Powder Bed Fusion (L-PBF) was utilized to fabricate fully dense, near-equiatomic (Ni50.1Ti49.9) and Ni-rich NiTi (Ni50.8Ti49.2) shape memory alloy (SMA) parts which exhibited tensile ductility up to 16%, shape memory strain of 6%, and tensile superelasticity up to 4%. Annealing heat treatments marginally improved the superelasticity of the as-fabricated Ni-rich NiTi parts due to the formation of a small volume fraction of Ni4Ti3 precipitates. The selection of optimum processing parameters that yielded fully dense parts was guided by a process optimization framework based on a computationally inexpensive analytical model used to predict the melt pool dimensions. The framework also included single-track experiments to validate the model predictions and a criterion for the maximum allowable hatch spacing to prevent the formation of lack of fusion porosity. This framework allowed for constructing L-PBF processing maps for the present NiTi SMAs and revealed that fully dense parts could be printed over a wide range of process parameters. By controlling the L-PBF process parameters, in particular laser power, laser scan speed, and volumetric energy density, in the processing space that result in fully dense parts, it was demonstrated systematically that the composition of the printed parts could be precisely changed by controlling the evaporation of Ni. The flexibility of parameter selection to print defect-free NiTi SMAs and composition control by preferential evaporation of Ni opens the possibility to print functional NiTi SMA parts or devices without post-processing.

Towards fundamentally based heap leaching scale-up

A procedure is proposed for the extrapolation of laboratory column leaching kinetics for commercial heap leaching design. It employs previously published models based on dual-porosity hydrology and chemical reactions occurring during diffusion via the regions holding immobile solution. Case studies were analysed for which both the column leaching and heap leaching performance had been recorded on acid-soluble copper, sulphide-copper and gold ores. Theoretical relationships were developed for the manner in which bulk density and dripper spacing were expected to affect the diffusional path length via the immobile solution of the column/heap. The resulting correlations were fitted to the case study data by means of a single empirical constant, p, to which an average value of 4.5 (a dimensionless value) could be assigned. The magnitude of p suggests that densification, i.e. compaction of the ore particle bed, results in a slight increase in the spacing of solution flow channels but a large increase of the tortuosity of diffusion pathways. In the case of narrow dripper spacing, the decrease in leaching kinetics upon scale-up can be attributed to the increase in bulk density. The proposed method identifies the maximum dripper spacing that can be used before the width of the dripper spacing has a stronger effect on the diffusional path length than the increase in bulk density. The effect of dripper spacing on the asymptotic extractions (extrapolated to time infinity) of the case studies was quantified. Confidence in the reliability of the method can be further improved if more case study data can be accessed.

Electro-geohydraulic estimation of shallow aquifers of Owerri and environs, Southeastern Nigeria using multiple empirical resistivity equations

Estimates of the geohydraulic parameters of the aquifers of Owerri and environs were carried out using different empirical resistivity equations with the objective of evaluating the predictive capabilities of the various equations. Forty Vertical Electrical Sounding (VES) data were acquired with a maximum half-current electrode spacing of 500 m using the Schlumberger electrode configuration. Aquifer resistivity across the study area varies from 330 to 78,100 Ωm with a mean value of 9465.8 Ωm. Aquifer depth ranges from 22.5 to 91.8 m with a mean value of 61.79 m while aquifer thickness across the study area ranges from 10.8 to 77.0 m with an average value of 36.72 m. The Dar-Zarrouk parameters revealed that the transverse resistance ranges from 12,276 to 2,297,120 Ωm2 with a mean value of 330,297.01 Ωm2 while the longitudinal conductance ranges between 0.000214 and 0.529231 Ω−1 with a mean value of 0.01323Ω−1. Aquifer hydraulic conductivity values vary from about 2.97–58.55 m/day with a mean value of 15.55 m/day while aquifer transmissivity values vary from about 37.433–7004.61 m2/day with a mean value of 1007.18 m2/day. Aquifer storativity values across the study area vary from 0.0000324 to 0.000231 with a mean value of 0.00011 while aquifer hydraulic diffusivity values ranged between 335,425 and 79,383,443.33 with a mean value of 9,621,354.647. Model ranking using statistical analysis revealed that out of the three different equations used for estimating hydraulic conductivity in the study area, the New Model equation is the best alternative in the absence of pumping test data.

An Innovative Service Load-Agnostic Structural Light-Weighting Design Optimization Methodology

<div class="section abstract"><div class="htmlview paragraph">A myriad of topology optimization tools exist today in the market that use automated under-the-hood structural simulations. All the user needs is to provide is the current shape of the part, or the maximum space that the part is allowed to occupy, and the maximum loads that it will experience. Though this technology has existed for over 25 years, recent advances in Additive Manufacturing (AM) have now enabled fabrication of hitherto-infeasible parts, both quickly and inexpensively.</div><div class="htmlview paragraph">A quick cursory literature search on successful implementation of topology optimization reveals that a majority of the attention has been focused on structural components and assemblies subjected to known service load(s) [<span class="xref">1</span>,<span class="xref">2</span>,<span class="xref">3</span>]. Therein lies one of the disadvantages experienced in the state-of-the-art today, especially for the military industry. The <i>magnitudes</i> of these loads are unknown <i>a priori</i> during design development, but rather only after vehicles are physically available, which is in much later design stages, and often too late to reap the benefits of optimization. In addition, enormous resources are required to measure loads in key components in physical tests, simply for performing topology optimization. In this study, a modeling and simulation (M&S) approach to optimization of structures in the absence of knowledge of service loads is described to determine the best weight save while simultaneously maintaining a similar or better “performance”.</div><div class="htmlview paragraph">Since the targets are with respect to zero or minimal performance gradation with respect to the baseline design, the premise of this research is that the optimization exercise can be carried out with relative loads, and knowledge of the absolute values are not necessary. This hypothesis has been successfully borne out in this paper, and the two design spaces explored meet all the set performance criteria compared to the baseline, and are able to achieve a weight save of up to 20%.</div></div>

Spatial assemblage and interference competition of introduced Brown Trout (Salmo trutta) in a Himalayan river network: Implications for native fish conservation

AbstractOften regarded as a potential threat to the native fish fauna worldwide, the Brown Trout (Salmo trutta), has successfully established its population in the majority of the Himalayan rivers post its introduction dating back to the eighteenth century. Over the years, the species has gained infamy as a sport fish and is considered a profitable source of income to the locals ensuing a heightened propagule pressure due to lack of appropriate management actions. No comprehensive study has been conducted to date in order to understand the mechanism by which the Brown Trout poses threat to the native fish populations. Through the present study, we could assess its competition with the native Snow Trout (Schizothorax richardsonii) to understand the spatial assemblage of both the species across space in Tirthan, a pristine high-altitude river of the western Himalaya. River Tirthan is one of the major tributaries of River Beas traversing for most of its stretch within the protected boundaries of the Great Himalayan National Park Conservation Area. A total of 108 sampling points were chosen from confluence to origin of rivers/streams, ranging from 989 to 3677msl. A total of 28 explanatory variables were recorded at each point. Overall, the Brown Trout adults were found to be greater in relative abundance (66.1%) than the Snow Trout adults (33.9%). The fingerlings of Snow Trout on the other hand, were distinctively high in relative abundance (61.9%) than those of the invasive Brown Trout (38.1%). Non-native trout showed higher abundance in the higher stream orders i.e. in the main streams while natives mostly restricted themselves to the lower order streams. Redundancy analysis (RDA) for species and environmental covariates resulted in 40.75% of constrained variance with higher eigen values for Redundancy analysis1 and Redundancy analysis2. Ward’s minimum variance clustering of Hellinger transformed data revealed sites agglomerating into six reasonable distinct subgroups with respect to species abundances. Immature individuals of non-native and native trout used similar habitat conditions, but they differed in using habitats at adult stage. Our results show a competitive dominance of Brown Trout in terms of higher abundance and maximum space utilization that highlight an urgent action for preventing its introductions to new areas. We recommend a national policy of ‘The Indian Invasive Species Act’ and management level interventions to control overstocking in the areas of established population.

Modeling of groundwater yield by the electrical method case of the Triassic sandstone aquifer (Tataouine South-Eastern Tunisia)

Abstract The method of electrical resistivity has proven very effective in the evaluation of groundwater. This specialized technique uses Dar-Zarrouk (D-Z) parameters in the estimation of longitudinal unit conductance, transverse unit resistance, and longitudinal resistivity to examine the groundwater level, to distinguish the fresh, brackish, and saline water interface, and to assess the storage capacity of groundwater in the Triassic sandstone aquifer system in the Tataouine region (South-Eastern Tunisia). In this context, 23 vertical electrical soundings (VESs) were carried out in the Tataouine region using the Schlumberger configuration with a current electrode with a maximum spacing of the current electrodes (AB) of 500–600 m. The results indicate that the study area consists of three types of aquifers: (i) silt/clay saline water (<20 Ωm), (ii) a mixture of sand and clay freshwater (20–40 Ωm), and (iii) sand freshwater (40–200 Ωm). These sand freshwater aquifers are characterized by low longitudinal unit conductance (0–2.8 S), high values of transverse unit resistance (more than 9,000 Ωm2), and longitudinal resistivity (more than 35 Ωm) and are mainly concentrated in the north, south, and south-west regions of the study area. It should also be noted that the coefficient of anisotropy (λ) overlaps and does not clearly differentiate the characteristics of the aquifers of fresh, brackish, and saline water. An interpretation of VESs can also determine the storage capacity of groundwater by determining yield index values. Groundwater supply for the entire study area was classified as low yield, with a percentage of 13% and a maximum of 31% of the study area and 56% of moderate yield. Lastly, the real data from the drilling confirm all these results presented previously. The findings suggest that D-Z parameters are useful for making a distinction of various aquifer zones.

Concrete crushing based on the high-voltage pulse discharge technology

High-voltage pulse discharge (HVPD) technology has a broad prospect in concrete crushing. The model of concrete beam sections is established by ANSYS/LS-DYNA finite element software. The shock wave, caused by the electrohydraulic effect of HVPD with 50 kJ energy, is equivalent to an explosive blast shock load. The analysis of concrete beam sections throughout loading was carried out. The section size of each beam segment is width × height = 400 mm × 800 mm, and the lengths of beams are: 600 mm, 700 mm, 800 mm, 900 mm, 1000 mm and 1100 mm respectively. The influence of aperture and spacing of holes on the crushing effect of the concrete beam segment was investigated. Two holes were drilled vertically on the wide and length surface of the concrete beam section, and the corresponding drilling spacing for each length of beam section is 200 mm, 300 mm, 400 mm, 500 mm, 600 mm and 700 mm respectively. The depth of holes in each beam is 450 mm, and the diameters of holes are 30 mm, 50 mm and 70 mm respectively. The analysis results show that with the increase of the hole diameter and the decrease of the hole spacing, the crushing effect of the concrete beam section is gradually enhanced. Depending on the crushing effect of the beam section, the optimal layout scheme is determined that the hole diameter is 50 mm, the hole spacing is 400 mm and the hole end (edge) spacing is 250 mm. A scheme is proposed to set multiple rows of holes in the width direction for the beams which have a large size. And the maximum row spacing of holes is the same as the maximum spacing of holes. The models of beam segments with width of 900 mm, 1300 mm and 1700 mm are established to verify the rationality of the arrangement scheme. Of the beam, the section size is 800 mm × 900 mm, the hole diameter is 50 mm, the hole spacing is 400 mm, and the hole row spacing is 400 mm. The analysis results show that the concrete beam segment is effectively crushed under the multi-row hole layout scheme.

Geo-electrical investigation of the groundwater potential of Ogidi and environs, Anambra State, South-eastern Nigeria

The electrical resistivity method was used to determine the groundwater potential of Ogidi and its environs. Thirteen soundings were carried out at thirteen different locations using the ABEM terrameter (SAS 1000), and adopting the Schlumberger configuration with maximum current electrode spacing of 1000 m. The lithologic logs for the boreholes were used to delineate the geologic sections. The results revealed six to nine geo-electric layers comprising laterite, clayey sandstone, sandstone, water-saturated sandstone and shale. The water-saturated sandstone forms the aquiferous unit. This unit was found to have resistivity values ranging from 363Ωm to 9107Ωm. It is deeply seated in some areas with a depth of 33.2–103 m. It was observed that the hydraulic conductivity varies between 0.001 and 0.066 m/day, while the transmissivity values vary between 0.01 and 4.7 m2/day. Among all the VES points studied, it was observed that VES 1 has the highest transmissivity value and the highest aquifer thickness. In view of the foregoing, it is expected that water will flow more from aquifer in VES 1 since groundwater flow from an aquifer is directly proportional to transmissivity.

Quantitative discovery and geophysical estimation of limestone deposits at Takowangwa area, Mokwa, North-Central Nigeria

Takowangwa area in Mokwa, Niger State, North-Central Nigeria was probed using Electrical Resistivity (ER) and Induced Potential (IP) methods to discover possible limestone deposits. The probe was conducted at five profiles, within which 25 Vertical Electrical Soundings (VES) were carried out. The Terrameter SAS 4000 for which the maximum current electrode spacing AB/2 was 100 m and the Schlumberger array were adopted for the soundings. The results from the computer modelling software (IP2WIN) revealed the occurrence of limestone deposits in all the five probed profile locations. This was inferred from the exhibited low resistivity and chargeability values which characterised all the profiles in their first and second geoelectric layers. The characterised low resistivity and chargeability values ranged respectively from 43 to 155 Ωm and 1.12 to 155 msec, while the thickness range was from 20.69 to 86.53 m. These two geophysical approaches (Electrical Resistivity and Induced Polarization) showed a good degree of correlation in the resistivity and chargeability values of the limestone and their varying quantities. This research work estimated the occurrence of vast limestone deposits of the magnitude 2.0 x 106 t which can be of very much economic importance in domestic, mining and industrial purposes. More detailed integrated geological, geophysical studies and drillholes to cover the study area and even with further extension beyond the probed area for better understanding of the economic potential of the study area were recommended.

Assessing the brittle crust thickness from strike-slip fault segments on Earth, Mars and Icy moons

Segment lengths along major strike-slip faults exhibit a size dependency related to the brittle crust thickness. These segments result in the formation of the localized “P-shear” deformation crossing and connecting the initial Riedels structures (i.e. en-echelon fault structures) which formed during the genesis stage of the fault zone. Mechanical models show that at all scales, the geometrical characteristics of the Riedels exhibit dependency on the thickness of the brittle layer. Combining the results of our mechanical discrete element model with several analogue experiments using sand, clay and gypsum, we have formulated a relationship between the orientation and spacing of Riedels and the thickness of the brittle layer. From this relationship, we derive that for a pure strike-slip mode, the maximum spacing between the Riedels is close to three times the thickness of the layer. For a transtensional mode, as the extensive component becomes predominant, the spacing distance at the surface becomes much smaller than the thickness. Applying this relationship to several well-characterized strike-slip faults on Earth, we show that the predicted brittle thickness is consistent with the seismogenic depth. Supposing the ubiquity of this phenomenon, we extented this relationship to characterize en-echelon structures observed on Mars, in the Memnonia region located West of Tharsis. Assuming that the outer ice shells of Ganymede, Enceladus and Europa, exhibit a brittle behavior, we suggest values of the corresponding apparent brittle thicknesses.

Maximum spacing estimation for continuous time Markov chains and semi-Markov processes

In this article, the maximum spacing (MSP) method is extended to continuous time Markov chains and semi-Markov processes and consistency of the MSP estimator is proved. For independent and identically distributed univariate observations the idea behind the MSP method is to approximate the Kullback–Leibler information so that each contribution is bounded from above. Following the same idea, the MSP function in this article is defined as an approximation of the relative entropy rate for semi-Markov processes and continuous time Markov chains. The MSP estimator is defined as the parameter value that maximizes the MSP function. Consistency of the MSP estimator is also studied when the assigned model is incorrect.