Adjacent Blocks Research Articles

Improving assessment of urban racial segregation by partitioning a region into racial enclaves

Frequently, a single-value metric is needed to rank urban regions with respect to the level of multiracial segregation or to compare a segregation level of a single urban region at two different times. Assessment of segregation depends not only on a metric used but also on a choice of region’s partitioning. The standard practice is to partition the region into single-scale subregions. In the United States, census tracts are the subregions of choice. Census aggregation units including tracts are delineated without a direct regard to racial homogeneity and are in fact heterogeneous. Consequently, using tracts as subdivisions leads to the underestimation of the segregation level of the entire region. Here we propose to partition a region into racial enclaves—units having boundaries that align with transitions between different racial compositions. By reflecting true demographic structure, such units minimize their internal racial inhomogeneity resulting in improved assessment of segregation. Enclaves are defined as aggregates of adjacent census blocks (smallest and the most racially homogeneous census units) of similar composition. In a typical US urban region, effective population size of enclaves is an order of magnitude larger than the size of a census tract and yet the segregation calculated based on enclaves is larger than segregation based on census tracts. The proposed methodology is described and applied to a set of 61 largest cities in the US in their metropolitan statistical areas as well as their urban areas boundaries using 1990 and 2010 block-level data. The method is compared to the standard methodology using correlations between cities’ segregation rankings.

An effective biometric identification system using enhanced palm texture features

Pattern recognition technologies aim to develop new techniques for transforming original data into other representations that honestly illustrate their content and can then be used to analyze and understand the original data. In the field of computer vision based on images, which is the dominant technology for machine vision solutions, image texture is a rich information source, used in many feature extraction techniques to obtain salient and distinctive features that were later used in pattern recognition applications. However, depending on the application, the extracted feature vector may be subject to some constraints such as length and accuracy. This work aims to develop a new texture-based feature extraction technique that can provide a feature vector with a high degree of distinction that can be controlled in terms of length and accuracy. The new scheme, called adjustable local binary pattern (A-LBP) or adjacent block features based LBP, derived from the original LBP, uses neighboring blocks and a linear relationship between the features of these blocks to form a binary codeword’s that can be used to represent the image. In our study, the block feature is extracted using the discrete cosine transform. To evaluate the performance of the proposed scheme, an A-LBP based biometric and bio-watermarking systems were developed.

A Block Aggregation Method for Short-Term Planning of Open Pit Mining with Multiple Processing Destinations

Clustering approaches are widely used to group similar objects and facilitate problem analysis and decision-making in many fields. During short-term planning of open-pit mines, clustering aims to aggregate similar blocks based on their attributes (e.g., geochemical grades, rock types, geometallurgical parameters) while honoring various constraints: i.e., cluster shapes, size, alignment with mining direction, destination, and rock type homogeneity. This approach helps to reduce the computational cost of optimizing short-term mine plans. Previous studies have presented ways to perform clustering without honoring constraints specific to mining. This paper presents a novel block clustering heuristic capable of considering and honoring a set of mining block aggregation requirements and constraints. Constraints can relate to the clustering adjacent blocks, achieving higher destination homogeneities, controlled cluster size, consistency with mining direction, and achieving clusters with mineable shapes and rock types’ homogeneity. The proposed algorithm’s application on two different datasets demonstrates its efficiency and capability in generating reasonable block clusters while meeting different predefined aggregation requirements and constraints.

Enhanced room‐temperature magnetoelectric coupling effects in c‐axis oriented polycrystalline BaSrCo2‐xMgxFe11AlO22

AbstractThe influence of applied magnetic field during annealing process as well as of Mg doping on the room‐temperature magnetoelectric coupling effects in BaSrCo2‐xMgxFe11AlO22 are experimentally studied through the magnetization, magnetodielectric, and magnetoelectric current measurements. Hexaferrite samples of Co2Y were found to be highly oriented by an applied magnetic field (Ho) during the annealing process, leading to an enhancement of the room‐temperature magnetoelectric coupling effects. Although the substitution of nonmagnetic Mg ions in Co sites tends to reduce the ferromagnetism at macroscopic scale, a proper amount of Mg doping content facilitates the superexchange interaction between the adjacent magnetic blocks; meanwhile modulates the magnetic anisotropy in the samples. An appropriate adjustment of the competition between the anisotropy and the superexchange could enhance the magnetoelectric coupling at room temperature, which can be confirmed by the magnetic‐field‐induced dielectric constant and current density study.

A proposal for an approach for meso scale modeling for concrete based on rigid body spring model

Existing meso-scale models of concrete need to refine the mesh grids of aggregate and cement mortar, which may greatly reduce the computational efficiency. To overcome this problem, a novel meso-scale modeling strategy, which is based on rigid body spring method and Voronoi diagram, is proposed in this study to establish the meso-scale model of concrete. Firstly, establish numerical aggregate models according to user-defined programs. Circle aggregates are adopted due to their high efficiency in generation and packing process, and the grading of aggregate are determined according to the distribution curve proposed by Full and Thompson; Secondly, extract the centroids of aggregates, and then develop the Voronoi diagram in which aggregate centroids are defined as initial scatters; Finally, establish the rigid body spring model for concrete based on the Voronoi diagram. Aggregates are represented by rigid blocks, and assumed to be unbreakable. Cement mortar is concentrated into the interface between adjacent blocks and represented by two uniform springs. The number of grids is consistent with that of aggregates in specimens, and no mesh-refinement of aggregates and cement mortar is required. The accuracy and efficiency of the proposed modeling strategy are firstly identified by comparing the numerical results with the experimental ones, and then the applicability of the proposed strategy with different volume percentage occupied by aggregates is investigated.

IPD-Based Miniaturized Wideband Bandpass Filter With Frequency-Dependent Complex Source and Load

In this article, an ultraminiaturized bandpass-filtering matching network based on GaAs substrate integrated passive device (IPD) technology is proposed, which is suitable for frequency-dependent complex source and load. The presented bandpass filter (BPF) is derived from an equal-ripple Chebyshev low-pass filter prototype through frequency transformation and impedance scaling. The susceptance required by the source and load is extracted from the adjacent susceptance blocks, and the final reactance/susceptance block is equivalent to a series/parallel LC circuit at the two edge frequencies. Therefore, the proposed design has both bandpass high-selectivity and impedance matching functions, and simultaneously, the bandwidth can be flexibly controlled. Finally, a wideband BPF example with the center frequency of 3.5 GHz was simulated and fabricated with the IPD process, showing satisfactory performances.

Factors Controlling Shale Reservoirs and Development Potential Evaluation: A Case Study

The shale of the Lower Silurian Longmaxi Formation is an important gas-producing layer for shale gas development in southern China. This set of shale reservoir characteristics and shale gas development potential provide an important foundation for shale gas development. This study takes wellblock XN111 in the Sichuan Basin, China, as an example and uses X-ray diffraction (XRD), scanning electron microscopy (SEM), isothermal adsorption, and other techniques to analyze the shale reservoir characteristics of the Lower Silurian Longmaxi Formation. The results show that the Lower Silurian Longmaxi Formation was deposited in a deep-water shelf environment. During this period, carbonaceous shale and siliceous shale characterized by a high brittle mineral content ( quartz > 40 wt . % , carbonate mineral > 10 wt . % ) and a low clay mineral content (<30 wt.%, mainly illite) were widely deposited throughout the region. The total organic carbon (TOC) content reaches up to 6.07 wt.%, with an average of 2.66 wt.%. The vitrinite reflectance is 1.6–2.28%, with an average of 2.05%. The methane adsorption capacity is 0.84–4.69 m3/t, with an average of 2.92 m3/t. Pores and fractures are developed in the shale reservoirs. The main reservoir space is composed of connected mesopores with an average porosity of 4.78%. The characteristics and development potential of the shale reservoirs in the Lower Silurian Longmaxi Formation are controlled by the following factors: (1) the widespread deep-water shelf deposition in wellblock XN111 was a favorable environment for the development of high-quality shale reservoirs with a cumulative thickness of up to 50 m; (2) the high TOC content enabled the shale reservoir to have a high free gas content and a high adsorptive gas storage capacity; and (3) the shale’s high maturity or over maturity is conducive to the development of pores and fractures in the organic matter, which effectively improves the storage capacity of the shale reservoirs. The reservoir characteristic index was constructed using the high-quality shale’s thickness, gas content, TOC, fracture density, and clay content. Using production data from shale gas wells in adjacent blocks, a mathematical relationship was established between the Estimated Ultimate Recovery (EUR) of a single well and the Reservoir Characteristics Index (Rci). The EUR of a single well in wellblock XN111 was estimated.

Image Encryption Scheme Based on Block Scrambling, Closed-Loop Diffusion, and DNA Molecular Mutation

A new image encryption scheme is proposed with a combination of block scrambling, closed-loop diffusion, and DNA molecular mutation. The new chaotic block scrambling mechanism is put forward to replace the traditional swapping rule by combining the rectangular-ambulatory-plane cyclic shift with the bidirectional random disorganization. The closed-loop diffusion strategy is designed to form a feedback system, which improves the anti-interference capacity of the algorithm. To further destroy the blocks characteristics and eliminate the correlations among adjacent blocks, two efficient methods of DNA molecular mutation are adopted in the mutation stage. Moreover, the proposed algorithm possesses a large key space and the keys are highly related with the plaintext image. Experimental results demonstrate that the suggested image encryption strategy is practicable and has strong ability against a variety of common attacks.

Design of coaxial magnetic gear utilising a novel permanent magnet Halbach array structure

Mechanical gears are constrained due to wear and tear and call for lubrication. A magnetic gear, utilising permanent magnet (PM) arrays, facilitates the mechanical gear roles. It can withstand high-speeds and large loads with zero friction. The magnetic gear is more efficacious on account of the least noise, performance, overload protection, and physical isolation between parts than conventional mechanical gears. The quantity of PMs in magnetic structures plays a principal role in its total price, which necessitates optimal arrangements for PMs. Halbach array provides a bigger torque density according to its one-sided flux. In this research, proposing a novel Halbach array structure, leads to intensification in the one-sided flux in a much sinusoidally waveform that consequently increases the magnetic torque. These all lead to gain higher torques in constant volumes of magnets. Besides, the magnetic torque ripple and the modulators’ losses are decremented. The new model is based on the variation of the magnetisation angles of the adjacent permanent magnet blocks, in the array. Various states of the magnetisation angles in the array are optimised based on a heuristic method. This is studied in the whole trigonometric range for magnetisation angles characteristics. The prototype is fabricated based on the optimised magnetic gear design and complies with the results.

1-Aminobicyclo[2.2.2]octane-2-carboxylic Acid and Derivatives As Chiral Constrained Bridged Scaffolds for Foldamers and Chiral Catalysts

The improvement of molecular diversity is one of the major concerns of chemists since the continuous development of original synthetic molecules provides unique scaffolds usable in organic and bioorganic chemistry. The challenge is to develop versatile platforms with highly controlled chemical three-dimensional space thanks to controlled chirality and conformational restraints. In this respect, cyclic β-amino acids are of great interest with applications in various fields of chemistry. In addition to their intrinsic biological properties, they are important precursors for the synthesis of new generations of bioactive compounds such as antibiotics, enzyme inhibitors, and antitumor agents. They have also been involved in asymmetric synthesis as efficient organo-catalysts in their free form and as derivatives. Finally, constrained cyclic β-amino acids have been incorporated into oligomers to successfully stabilize original structures in foldamer science with recent successes in health, material science, and catalysis. Over the last ∼10 years, we focused on bicyclic β-amino acids possessing a bicyclo[2.2.2]octane structure. This latter is a structural key element in numerous families of biologically active natural and synthetic products and is an interesting template for asymmetric synthesis. Nonetheless, reported studies on bicyclic carbo-bridged compounds are rather limited compared to those on bicyclic-fused and heterobridged derivatives. In this Account, we particularly focused on the synthesis and applications of the 1-aminobicyclo[2.2.2]octane-2-carboxylic acid, named, ABOC, and its derivatives. This highly constrained bicyclic β-amino acid, with a sterically hindered bridgehead primary amine and an endocyclic chiral center, displays drastically reduced conformational freedom. In addition, its high bulkiness strongly impacts the spatial orientation of the appended functionalities and the conformation of adjacent building blocks. Thus, we have first expanded a fundamental synthetic work by a wide ranging study in the field of foldamers, in the design of various stable peptide/peptidomimetic helical structures incorporating the ABOC residue (11/9-, 18/16-, 12/14/14-, and 12/10-helices). In addition, such bicyclic residue was fully compatible with and stabilized the canonical oligourea helix, whereas very few cyclic β-amino acids have been incorporated into oligoureas. In addition, we have pursued with the synthesis of some ABOC derivatives, in particular the 1,2-diaminobicyclo[2.2.2]octane chiral diamine, named DABO, and its investigation in chiral catalytic systems. Covalent organo-catalysis of the aldol reaction using ABOC-containing tripeptide catalysts provided a range of aldol products with high enantioselectivity. Moreover, the double reductive condensation of DABO with various aldehydes allowed the building of new chiral ligands that proved their efficiency in the copper-catalyzed asymmetric Henry reaction.

Polyoxotungstates-supported NiII/CoII-containing 3D inorganic-organic hybrids as supercapacitor electrodes toward boosting capacitor performance

Herein, five new polyoxotungstates (POTs)-based NiII/CoII-containing 3D inorganic-organic hybrid compounds, [H5(SiW9VIW3VO40)3Ni8(H2O)12(atrz)12]·12H2O (SiW12-Ni8), [H2(PW9VIW3VO40)3Ni8(H2O)12(atrz)12]1/3·4H2O (PW12-Ni8), [H11(CoW9VIW3VO40) 3Ni8(H2O)12(atrz]12]·12H2O (CoW12-Ni8), [H11 (CoW9VIW3VO40) 3Co8(H2O)12(atrz)12]·12H2O (CoW12-Co8), [H2(PW9VIW3VO40)3Co8(H2O)12(atrz)12] 1/3·4H2O (PW12-Co8) (atrz = 4-amino-1,2,4-triazole) have been synthesized via hydrothermal reaction and explored as pseudocapacitive electrode materials. Single-crystal X-ray diffraction displays these compounds have isostructural three-dimensional (3D) configuration and possess a (3,4)-connected (83)4(72. 82)3 topology structrue. Compared to others, CoW12-Ni8 as electrode materials shows the highest specific capacitance (526.1 F g−1 at 1.0 A g−1) and only experiences 16% capacitance loss at a high charge/discharge current density of 10 A g−1 after 1000 cycles. The capacitance ability of these POTs-based compounds is mainly dominated by the substituted heteroatoms (Co, Si, or P) in POTs and the coordinated metal (NiII or CoII) in the adjacent building blocks. This work may develop a new path to optimize the performance of POTs-based energy functional materials.

Neoproterozoic magmatic and metamorphic imprints in the East Kunlun Orogenic Belt, North Tibetan Plateau, NW China: Implications for the assembly and initial breakup of the Rodinia supercontinent

The East Kunlun Orogenic Belt (EKOB), located on the northern margin of the Tibetan Plateau, experienced intense, long-lasting,and complicatedmulti-stage orogeny from the Neoproterozoic to Early Mesozoic. Neoproterozoic magmatic and metamorphic events recorded critical information on Precambrian tectonic evolutionary history. Zircon U-Pb ages of 914 ± 6.5, 902 ± 5.3, and 856 ± 6.8 Ma were determined for granitic gneiss, monzogranite, and charnockite, respectively. Geochemical and petrological studies reveal high SiO2, Al2O3, and K2O content with abundant Al-rich minerals, such as garnet and muscovite, which show typical S-type granite properties. The εHf(t) values ranging from − 6.5 to + 5.6 (TDM2 = 1.4–2.2 Ga) indicate a primarily Paleoproterozoic metagreywackes and metapelitic derivation with mantle contribution. Zircon U-Pb results show that amphibolite yielded ages of 846 ± 5.2 Ma. Geochemistry andεHf(t) values ranging from 10.5 to 15.9 (TDM1 = 0.8–0.9 Ga) suggest that the mafic magma originated from depleted mantle metasomatized by subduction fluid. We propose that the Neoproterozoic rocks in this study were generated in syn-orogenesis and incipient continental rift-related extension environment, whichcorresponds to the assembly and initial breakup of the Rodinia supercontinent. In the EKOB, The initial breakup-related extension of the supercontinent affected by super plume occurred at ca. ~ 0.85 Ga. East Kunlun and its adjacent blocks were within a single tectonic domain and recorded important evolutionary history of the Rodinia supercontinent.

“Frame Wobbling” Causing Crustal Deformation Around the Ordos Block

AbstractAn accurate and dense GPS velocity field across the Ordos block is presented based on extensive observations. We utilized velocities from evenly distributed GPS stations within the block to estimate the parameters of rigid block motion and internal strain. Our results indicate that the Ordos block behaves rigidly, with a negligible anticlockwise rotation. The velocity profiles, strain, and block motion suggest that: the interior of the block undergoes no differential motion and internal strain is insignificant; relative to the Ordos, the adjacent blocks move in different directions and at different rates, and exert varying forces on it; the adjacent blocks deform the Ordos block along its boundaries of grabens and fold‐thrust fault zones. The Ordos block accommodates the forces exerted by the adjacent blocks through strain and deformation across its boundaries, which should be high strain or strain gradient zones. This pattern of deformation is illustrated by frame wobbling.

ALMNet: Adjacent Layer Driven Multiscale Features for Salient Object Detection

Nowadays, the usage of deep learning-based approaches for salient object detection (SOD) is increasing exponentially to detect and localize visually distinct regions in static images. However, the variability in scales of salient objects requires further attention given the abstract nature of the multilayer feature hierarchy of convolution neural networks (CNNs). First, feature maps of different layers in CNNs embed abstract information about objects that changes with the object’s scale. Second, the progressive feature fusion in models, such as the feature pyramid network, loses its effectiveness in detecting sharp boundaries due to the late fusion of detailed features. This work proposes two modules namely, adjacent layer attention block and partial encoder–decoder (PED) block to handle the aforementioned issues. The proposed adjacent layer attention block facilitates communication among the layers of closest abstraction to mine abundant scale features at the current resolution. The resultant integrated feature at a resolution contains detailed and semantic information from interaction among the adjacent layers useful to extract scale information of complex objects. A PED module utilizes the resolution-specific integrated features from the adjacent layer attention block of its corresponding encoder to generate multiscale features, and fuse them in a top-down manner. This level-specific distribution of aggregated features within a PED helps coarser layers of the network to acquire boundary information. Experimental results on five broadly used SOD datasets are compared with recent 20 state-of-the-art SOD models. The proposed method performs favorably against its competitors without any preprocessing or postprocessing.

Intra Prediction-Based Measurement Coding Algorithm for Block-Based Compressive Sensing Images

Block-based compressive image sensor (BCIS) captures light and represents them as compressed data called measurement. It has potential to revolutionize conventional image and video acquisition system that builds upon high complexity and redundant process. However, by comparing the compression performance between these two systems, BCIS cannot reduce bitrate to similar factor as the compressed media by pixel-based compression algorithms. It still requires enormous amounts of bit to store and transmit data. In this work, we introduce intra prediction based measurement coding algorithm for giving an extra compression performance to measurement. Moreover, importantly, there is a requirement that sensing matrix for BCIS must not be derived from non-uniform distribution in order to control prediction accuracy and quality. Therefore, we use structural sensing matrix made of sequency-ordered Walsh-Hadamard. Furthermore, it allows boundary pixels of adjacent blocks to be accessible through measurement, which helps intra prediction to generate its candidates accurately. The algorithm encodes prediction error between target measurement and multiple prediction candidates, resulting in smaller data size. This work can significantly reduce bpp by 10.90% and simultaneously increase 3.95 dB in PSNR compared to the state-of-the-art works. Moreover, we implemented the proposal on FPGA. It gave 10 times higher throughput than software. The core power consumption is at 50 mW and working at 88 MHz when processing 3840×2160 pixels with the sampling rate of 1/4.

Determination of Proper Water Supply Rate for Emergency Interconnection Plan

The deterioration of water supply networks leads to frequent accidents, such as pipe failure, which result in water service interruptions. Depending on the type of accident, a large-scale water service interruption can occur. Therefore, an emergency interconnection plan has been established to prevent interruptions in water service. However, most emergency interconnection plans only consider whether water can be supplied to the region of water service interruption. The area that can actually supply water, emergency water supply area (EWSA), and the possible time required to supply water, emergency water supply time (EWST) are not usually considered. Furthermore, in cases wherein the adjacent local governments or adjacent water supply blocks have insufficient water for the region of water service interruption, it is a good practice to increase the possible water supply time by the reducing the water supply rate (WSR) in order to minimize the damage from the water service interruption. In this study, a method is suggested to determine the proper WSR required to minimize the damage when the amount of emergency water is insufficient. Since it is a case where the amount of emergency water is not sufficient, A-PDA is used to simulate EWSA and EWSA for each WSR. The simulation results are subsequently converted into the customer satisfaction index for each WSR. Through this procedure, the proper WSR can be determined, thereby improving both customer satisfaction and water supply time. Finally, this method is applied to a real water supply network to verify its applicability.

Another way of looking at an Alkaline Province

The Mesozoic Alkaline Magmatism on the South American Platform is related to the Gondwana breakup and the opening of the South Atlantic Ocean. This event, known as the Mesozoic Activation phase, was responsible for five magmatic pulses, among them the Late Cretaceous-Eocene Alkaline Magmatism, which implemented ten alkaline provinces, eight of which are in the south-central portion of Brazil. Some authors claim that the reactivation of old zones of weakness from the Precambrian basement, Brasiliano orogeny, may have been responsible for the structuring of few bodies in these provinces. This work used geophysical processing techniques to interpret magnetic and gravity data and 2.5 D forward modeling to contribute with the knowledge on the tectonic control over the Goiás Alkaline Province. The geophysical data processing show a tectonic control over the Goiás Alkaline Province, along the Brasiliano and Mesozoic structures, and there was no predominance of alkaline bodies along the Azimuth 125. We find that the Brasiliano orogeny structures limited the crustal block that contains this Province and Gondwana breakup possibly created and reactivated these structures. We discuss the continuity of large structures, at different depths, related to the Tocantins Province, mainly in the Brasília belt, and some of them can be observed down to approximately 20 km depth. The forward gravity modeling beneath the Goiás Alkaline Province shows a thicker crust and we propose that the primitive lithospheric mantle below this province was not altered during the Brasiliano orogeny stages, as in the adjacent crustal blocks, thus allowing for generation of alkaline rocks. Along the modelled section the Arenópolis Magmatic Arc was separated into two different crustal blocks; the western arc whitin the Goias Alkaline Province, and the eastern arc where the mantle was altered due to its collision with the São Francisco Paleocontinent.

A Partially Coherent Approach for Modeling Polar Ice Sheet 0.5–2-GHz Thermal Emission

The Ultra-Wideband Software Defined Microwave Radiometer (UWBRAD) is a wideband radiometer operating from 0.5 to 2 GHz for remote sensing of polar ice sheet temperature profiles. Small-scale (cm to m) fluctuations in firn density in the upper portion of the ice sheet significantly impact observed brightness temperatures. Previously, a fully coherent model based on solving Maxwell’s equations for thousands of layers throughout the entire ice sheet was developed. Density profiles in the model are described as the sum of a smooth average density profile with a spatially correlated random process that represents density fluctuations. In this article, we develop a “partially coherent” implementation of the coherent model that captures the impact of variations in ice density on predicted brightness temperatures while improving computational efficiency. The partially coherent model divides the ice sheet into blocks. Within each block, the coherent model is applied to take into account coherence among the contributions of closely spaced layers. A Monte Carlo procedure is used to calculate the average block reflection and transmission parameters. Between adjacent blocks, interactions are assumed to be incoherent, and the radiative transfer theory is used to incoherently cascade block parameters. Results of the partially coherent model are in good agreement with the fully coherent model and also with Soil Moisture Ocean Salinity (SMOS) and UWBRAD brightness temperature observations.

Experimental and Modelling Study of Gravity Drainage in a Three-Block System

Gravity drainage is known as the controlling mechanism of oil recovery in naturally fractured reservoirs. The efficiency of this mechanism is controlled by block-to-block interactions through capillary continuity and/or reinfiltration processes. In this study, at first, several free-fall gravity drainage experiments were conducted on a well-designed three-block apparatus and the role of tilt angle, spacers’ permeability, wettability and effective contact area (representing a different status of the block-to-block interactions between matrix blocks) on the recovery efficiency were investigated. Then, an experimental-based numerical model of free-fall gravity drainage process was developed, validated and used for monitoring the saturation profiles along with the matrix blocks. Results showed that gas wetting condition of horizontal fracture weakens the capillary continuity and in consequence decreases the recovery factor in comparison with the original liquid wetting condition. Moreover, higher spacers’ permeability increases oil recovery at early times, while it decreases the ultimate recovery factor. Tilt angle from the vertical axis decreases recovery factor, due to greater connectivity of matrix blocks to vertical fracture and consequent channelling. Decreasing horizontal fracture aperture decreases recovery at early times but increases the ultimate recovery due to a greater extent of capillary continuity between the adjacent blocks. Well match observed between the numerical model results and the experimental data of oil recovery makes the COMSOL multiphysics model attractive for application in multi-blocks fractured systems considering block-to-block interactions. The findings of this research improve our understanding of the role of different fracture properties on the block-to-block interactions and how they change the ultimate recovery of a multi-block system.

Fast and robust image watermarking method in the spatial domain

To solve the copyright protection problem of a colour image, a new blind colour image watermarking method combining a discrete cosine transform (DCT) in the spatial domain is presented in this study. The advantages of the spatial-domain watermarking algorithm and frequency-domain one are made full use in this scheme. Based on the different quantisation steps in red, green, and blue three-layer images, the processes of watermark embedding and blind extraction are completed in the spatial domain without a real DCT domain. The scheme is realised by using the unique features of the direct current (DC) coefficient and the relativity of DC coefficients between adjacent pixel blocks. This scheme can effectively solve the problems of the large-capacity colour image watermarking algorithm, such as long-running time and weak robustness. Comparing with other advanced watermarking algorithms, the presented scheme has better invisibility, stronger robustness, and higher real-time performance.