Flat Region Research Articles

Infrared Dim and Small Target Detection Based on Superpixel Segmentation and Spatiotemporal Cluster 4D Fully-Connected Tensor Network Decomposition

The detection of infrared dim and small targets in complex backgrounds is very challenging because of the low signal-to-noise ratio of targets and the drastic change in background. Low-rank sparse decomposition based on the structural characteristics of infrared images has attracted the attention of many scholars because of its good interpretability. In order to improve the sensitivity of sliding window size, insufficient utilization of time series information, and inaccurate tensor rank in existing methods, a four-dimensional tensor model based on superpixel segmentation and statistical clustering is proposed for infrared dim and small target detection (ISTD). First, the idea of superpixel segmentation is proposed to eliminate the dependence of the algorithm on selection of the sliding window size. Second, based on the improved structure tensor theory, the image pixels are statistically clustered into three types: corner region, flat region, and edge region, and are assigned different weights to reduce the influence of background edges. Next, in order to better use spatiotemporal correlation, a Four-Dimensional Fully-Connected Tensor Network (4D-FCTN) model is proposed in which 3D patches with the same feature types are rearranged into the same group to form a four-dimensional tensor. Finally, the FCTN decomposition method is used to decompose the clustered tensor into low-dimensional tensors, with the alternating direction multiplier method (ADMM) used to decompose the low-rank background part and sparse target part. We validated our model across various datasets, employing cutting-edge methodologies to assess its effectiveness in terms of detection precision and reduction of background interference. A comparative analysis corroborated the superiority of our proposed approach over prevailing techniques.

DERIVATION OF BUILDING STRUCTURES FROM NOISY DIGITAL SURFACE MODELS

Abstract. In this work we present a novel approach for segementation of a noisy DSM to building structures and other non-building structures – normally trees – and the modeling of them. Mostly Digital Surface Models (DSMs) from only a few aerial images or only from one pair of satellite images tend to be very noisy and lack good quality especially in shadow areas. Since actual methods for deriving roofs rely on a valid height information by joining areas of same slope to a roof-plane these fail regularly with such noisy DSMs. In our presented approach we use a slope map of the DSM only to detect flat regions. Since those regions on top of roofs are mostly good illuminated we can derive the ridges of roofs and flat roofs and also ground areas. All narrow, flat, elevated areas are ridges and may occur on roofs or on trees. After connecting ridges in ridge-directions there remain two types of ridges: long, straight ridges of roofs and mixed short ridges in many directions for the trees. Fitting symmetric planes through the roof-ridge-lines gives finally the roof-planes reducing the effects of noise on shadowed parts of the roof. Taking the other tree-ridges as seeds for a watershed transformation will give the trees. Finally the proposed method is applied to a noisy DSM and the results will be discussed.

Route-Based Energy Analysis of Hybrid Rail Consists

Abstract Adding battery locomotives to traditional diesel locomotives to form a hybrid consist has the potential to reduce fuel consumption and emissions in freight rail operations. This paper provides route-based estimates of diesel (hpd/ton) and battery (hpb/ton) power requirements and diesel (gal/ton) and battery (hpbhr/ton) energy requirements for hybrid consists. Given a route-specific power profile, the power split between the battery pack and the diesel engine is optimized to minimize fuel consumption by running the diesel engine at maximum efficiency during the entire route. Simulations for 200-mile round trips between Chicago and Harrisburg show that the diesel power is maximum in low-gradient regions at 1.05 (hpd/ton) and battery power is maximum in hilly regions at 2 (hpb/ton) for discharge and 6.5 (hpb/ton) for charge. Maximum fuel efficiency gains of approximately 60% are seen in the mountains, where 2.09 (hpbhr/ton) of battery energy is needed. Minimum fuel economy gains are observed in flat regions, with 20% fuel consumption reduction. With battery current and voltage limits, the battery pack size increases, and fuel savings decrease.

Unification: Emergent universe followed by inflation and dark epochs from multi-field theory

A two scalar field model that incorporates non Riemannian Measures of integration or usually called Two Measures Theory (TMT) is introduced, in order to unify the early and present universe. In the Einstein frame a K-essence is generated and as a consequence for the early universe, we can have a Non Singular Emergent universe followed by Inflation and for the present universe dark epochs with consistent generation of dark energy (DE), dark matter (DM) and stiff matter. The scale invariance is introduced and then is spontaneously broken from the integration of the degrees of freedom associated with the modified measures. The resulting effective potentials and K-essence in the Einstein frame produce three flat regions corresponding to the different epochs mentioned before. For the first flat region we can associate an emergent and an inflationary universe. Here for a parameter-space region this flat plateau possesses a non singular stable emergent universe solution which characterizes an initial epoch of evolution that precedes the inflationary scenario. Also assuming this first plateau, we study the inflation in the framework of the slow-roll approximation. In this scenario under the slow roll approximation we obtain a linear combination that is a constant. The corresponding cosmological perturbations in our model are determined and we also obtain the different constrains on the parameter-space from the Planck data.In the following flat region DE and also the DM, which does not need to be introduced separately, it is instead a result of a K-essence induced by the multi measures, multi field theory. Also stiff matter component is automatically generated from the K-essence theory from two scalar fields. From the perturbative analysis associated to the perturbation solution of background, we find a correlation between the two scalars. Besides, we obtain that our model during the dark epoch has a behavior of tracking freezing model.

Spatial Coupling of Population and Economic Densities and the Effect of Topography in Anhui Province, China, at a Grid Scale

The spatial coupling of population and economy is an important indicator that reflects regional differences and measures the coordination degree of industrial layouts and environments. To explore the spatial coupling of population and economic densities and the effect of topography in Anhui Province at a grid scale, a land-use impact model was used to spatialize socio-economic indicators in Anhui Province using 2020 county-level data. Geographical concentration and coupling index were used to quantify the spatial relationship between population and economic densities. Then the effects of topography were assessed. The results show the following: (1) the accuracy of the regression models for the individual counties is generally better than that of the models for the whole region. The population and economic densities predicted by the proposed model reflect actual conditions. (2) Topography has a stronger effect on population density and primary industry density than on secondary and tertiary industry density. Slope has the strongest effect on population and economic densities, followed by topographic relief and elevation. (3) A spatial correlation exists between topographic factors and population and economic densities. Although the spatial relationship between population and economic densities is predominantly of the balanced development type in regions with complex topography, population and economic densities are significantly lower in regions with complex rather than flat topography. In addition, economic development in the northern Anhui region, a flat region, lags behind population aggregation. Efforts should be made to improve the economic level of the southern and northern Anhui regions and the Dabie Mountain region in western Anhui.

Ultimate uniaxial compressive resistance of S600E cold-formed stainless steel square tubes

Sorbite stainless steel (S600E, SSS) is a promising alternative for conventional metals in diverse engineering applications due to its exceptional mechanical properties, superior corrosion resistance, weldability, and cost-effectiveness. Nonetheless, its understudied mechanical behavior hinders its widespread employment as a prospective structural element. To enrich the mechanical understanding of SSS, tensile coupons, uniaxial compressive stubs, and long columns with cold-formed square hollow sections (SHS) were examined, elucidating the stress-strain graphs, failure mechanisms, and uniaxial resistance. The yield stress of S600E reaches 700 and 870 MPa in the flat and corner regions. Furthermore, local buckling occurs in all stubs featuring symmetrical bulges at one end, with a mean ultimate compressive resistance of 670 MPa. Conversely, most long columns fail due to global buckling. To determine an appropriate capability estimation, the experimental and finite element model (FEM) data were compared with the theoretical outcomes of presently available methods. The continuous strength method (CSM) and most specifications provide conservative assessments of the load-carrying capacity of stubs, where CECS 410:2015 produces a relatively accurate evaluation, displaying a 1% error. Regarding long columns, the improved direct strength method (DSM) accurately predicts the uniaxial resistance with a 1% error. This study illuminates the mechanical behavior of S600E, providing critical insights that enable more efficient use of this promising material in engineering and construction applications.

Robust multi-scale weighting-based edge-smoothing filter for single image dehazing

The guided image filter (GIF) and weighted guided image filter (WGIF) are local linear model-based good edge-preserving filters. However, due to fixed regularization parameter, they suffer from halo artifacts (morphological artifacts) in the sharp regions. To overcome this issue, a robust multi-scale weighting-based edge-smoothing filter (RMWEF) for single image dehazing is proposed in this paper. It removes morphological artifacts and over-smoothness strongly and preserves edge information precisely in both flat and sharp regions. The proposed dehaze method has four-steps. First, initial transmission map and atmospheric map are estimated by using a novel dark channel prior (DCP) method. Then, the morphological artifacts of initial transmission map are reduced by using non-local haze line averaging (NL-HLA) method. In the third step, transmission map is refined by using the proposed RMWEF. Finally, the haze free image is restored. Theoretical and experimental analysis proves that the proposed algorithm produce effective dehaze results quicker than the existing methods.

Mechanical properties and microstructure characteristics of wire arc additively manufactured high-strength steels

Additive manufacturing is a revolutionary emerging technology in the manufacturing industry. Wire arc additive manufacturing (WAAM) is a metal additive manufacturing technology suitable for the production of medium to large steel elements of structure. The aim of this study is to investigate the microstructural and mechanical behavior of high-strength steels produced by WAAM through experimental program. The test specimens were additively manufactured from three types of feedstock wires (ER100S-G, ER110S-G, ER120S-G). The microstructure characteristics of WAAM high-strength steels were identified. The tensile coupon specimens were extracted from flat regions of the WAAM runway-shaped steel tubes at five orientations θ = 0˚, 30˚, 45˚, 60˚, 90˚ with respect to the print direction to investigate the anisotropy of mechanical properties. Both the milled and as-built specimens were included to study the impact of geometric irregularity. The dimensions of the as-built specimens were measured using 3D laser scanning and the geometric characteristics were discussed. A total of 60 tensile tests were conducted with the assistance of digital image correlation (DIC) system in order to investigate the stress–strain responses of WAAM high-strength steels. Details of test program, including the specimen design, test setup and key test results, are presented. The anisotropy of WAAM high-strength steel specimens in terms of both the geometries and mechanical properties are discussed.

Free‐form reinforced concrete, prestressed concrete, and composite components: Calculation of cross‐section values

AbstractA resource‐efficient use of concrete as a construction material can be achieved by adapting the individual shape of a component under consideration to the stresses that occur and by arranging composite construction materials (e.g., reinforcing steel, prestressing steel, or structural steel) in suitable areas of the component. Due to the advancing digitalization in the construction industry, for example in the context of Building Information Modeling, computer‐aided 3D modeling methods are increasingly being used in the planning of structures. These allow engineers to design components in free form. In reinforced concrete, prestressed concrete, and composite construction, the design of such components is currently still associated with great effort. In the context of the development of a practical method for the calculation of free‐form concrete components, this paper presents a CAD‐integrated method for the calculation of cross‐section values. Cross‐section values are required as an essential calculation basis when real, three‐dimensional structural components are treated using simplified calculation theories, such as the beam theory. In this paper, the mathematical and numerical fundamentals of a method for the calculation of cross‐section values of free‐form concrete, reinforced concrete, prestressed concrete, and compound components are presented. The calculation method is based on flat geometric regions described by Non‐uniform Rational B‐Spline tensor product surfaces, which can be extracted from solid models, for example.

Can smartphones be used for routine dental clinical application? A validation study for using smartphone-generated 3D facial images

ObjectivesTo compare the accuracy of smartphone-generated three-dimensional (3D) facial images to that of direct anthropometry (DA) and 3dMD with the aim of assessing the validity and reliability of smartphone-generated 3D facial images for routine clinical applications. Materials and methodsTwenty-five anthropometric soft-tissue facial landmarks were labelled manually on 22 orthognathic surgery patients (11 males and 11 females; mean age 26.2 ± 5.3 years). For each labelled face, two imaging operations were performed using two different surface imaging systems: 3dMDface and Bellus3D FaceApp. Next, 42 inter-landmark facial measurements amongst the identified facial landmarks were measured directly on each labelled face and also digitally on 3D facial images. The measurements obtained from smartphone-generated 3D facial images (SGI) were statistically compared with those from DA and 3dMD. ResultsSGI had slightly higher measurement values than DA and 3dMD, but there was no statistically significant difference between the mean values of inter-landmark measures across the three methods. Clinically acceptable differences (≤3 mm or ≤5°) were observed for 67 % and 74 % of measurements with good agreement between DA and SGI, and 3dMD and SGI, respectively. An overall small systematic bias of ± 0.2 mm was observed between the three methods. Furthermore, the mean absolute difference between DA and SGI methods was highest for linear (1.41 ± 0.33 mm) as well as angular measurements (3.07 ± 0.73°). ConclusionsSGI demonstrated fair trueness compared to DA and 3dMD. The central region and flat areas of the face in SGI are more accurate. Despite this, SGI have limited clinical application, and the panfacial accuracy of the SGI would be more desirable from a clinical application standpoint. Clinical significanceThe usage of SGI in clinical practice for region-specific macro-proportional facial assessment involving central and flat regions of the face or for patient education purposes, which does not require accuracy within 3 mm and 5° can be considered.

Experimental investigation on deformation and failure mechanism of waste dump with partial-weak basement

A non-uniform basement condition usually causes dump disasters. Two sets of base friction tests were carried out to discuss the deformation mechanism of the waste dump with partial-weak and total-hard basement. By the image speckle analysis and point-tracking technology, dump displacements and strains were obtained, and the deformation mechanism, stability, failure process of the waste dump were analysed. We could concluded that: (1) a waste dump with total-hard basement has higher stability than that with partial-weak basement. (2) The dump displacement exhibits a distribution of five flat regions that are connected by four steep increasing regions. (3) The dump deformation could be categorized into three phases: continuous deformation phase, crack-failure phase and final stability phase. In crack-failure phase, the deformation process of a total-hard basement waste dump presents a traction-crack-slide feature, but that of a partial-weak basement waste dump exhibits a subsidence-crack-rotation pattern. (4) In the deformation process, a total-hard basement waste dump is mainly affected by tensile stress, and its crack type is classified as tensile crack. While a partial-weak basement waste dump is subject to the coupling action of tensile and shear stress, and its crack type is shear crack. Both total-hard and partial-weak basement waste dumps show volume expansion. (5) With regard to the deformation control project of partial-weak basement waste dumps, strengthening the weak basement and increasing the anti-sliding force of the dump slope are recommended to reduce the vertical and horizontal deformation. These results have guiding significance for the deformation mechanism, stability evaluation and reinforcement measures of partial-weak basement waste dumps.

Constructing traversable wormhole solutions in [formula omitted] theory

This paper aims to explore the viable and stable geometry of traversable wormholes in the framework of f(R,Lm) theory. For this purpose, we build a shape function using the Karmarkar condition that determines the geometry of the wormhole. The resulting shape function meets all the fundamental requirements and successfully establishes a connection between two asymptotically flat regions of the spacetime. We then formulate the field equations corresponding to two different models of this theory, representing static spherically symmetric anisotropic fluid distribution. We also check feasibility of the obtained wormhole solutions by graphically analyzing the behavior of null energy conditions. Finally, we examine the stability of these solutions through the speed of sound and adiabatic index criteria. We conclude that both our resulting models are well-agreed with the requirements needed for the existence of wormholes for chosen parametric values.

Plausible photomolecular effect leading to water evaporation exceeding the thermal limit.

We report in this work several unexpected experimental observations on evaporation from hydrogels under visible light illumination. 1) Partially wetted hydrogels become absorbing in the visible spectral range, where the absorption by both the water and the hydrogel materials is negligible. 2) Illumination of hydrogel under solar or visible-spectrum light-emitting diode leads to evaporation rates exceeding the thermal evaporation limit, even in hydrogels without additional absorbers. 3) The evaporation rates are wavelength dependent, peaking at 520 nm. 4) Temperature of the vapor phase becomes cooler under light illumination and shows a flat region due to breaking-up of the clusters that saturates air. And 5) vapor phase transmission spectra under light show new features and peak shifts. We interpret these observations by introducing the hypothesis that photons in the visible spectrum can cleave water clusters off surfaces due to large electrical field gradients and quadrupole force on molecular clusters. We call the light-induced evaporation process the photomolecular effect. The photomolecular evaporation might be happening widely in nature, potentially impacting climate and plants' growth, and can be exploited for clean water and energy technologies.

Development of a low-frequency accelerometer based on symmetric multi-stage triangular beam fiber Bragg grating

In order to meet the needs of accelerometers for low-frequency seismic exploration, a fiber-optic grating accelerometer based on a symmetric multi-stage triangular hinge is proposed. The sensitivity of the accelerometer is improved by the symmetrical multi-stage triangular beam structure, and experimental verification is carried out. The resonant frequency and sensitivity equations of the accelerometer are given based on theoretical analysis, while the finite element analysis software is used to simulate and analyze the characteristics of the accelerometer such as resonant frequency, stress distribution, and amplitude-frequency response. The structural parameters of the accelerometer are optimized by numerical analysis software, and the influence of the structural parameters on the sensitivity and resonant frequency of the accelerometer is analyzed. The experimental results show that the accelerometer has a resonant frequency of 140 Hz and a linearity of 99.9 % in the flat region of 1–70 Hz, a sensitivity of 337.325 pm/g, and an interference immunity of 5.39 % in the lateral direction in the working axis direction. This indicates that the accelerometer shows good linearity and lateral interference immunity in the flat interval, which well meets the needs of seismic wave signal monitoring in the field of low-frequency oil and gas exploration.

Image Defogging Based on Regional Gradient Constrained Prior

Foggy days limit the functionality of outdoor surveillance systems. However, it is still a challenge for existing methods to maintain the uniformity of defogging between image regions with a similar depth of field and large differences in appearance. To address above problem, this article proposes a regional gradient constrained prior (RGCP) for defogging that uses the piecewise smoothing characteristic of the scene structure to achieve accurate estimation and reliable constraint of the transmission. RGCP first derives that when adjacent similar pixels in the fog image are aggregated and spatially divided into regions, clusters of region pixels in RGB space conform to a chi-square distribution. The offset of the confidence boundary of the clusters can be regarded as the initial transmission of each region. RGCP further uses a gradient distribution to distinguish different regional appearances and formulate an interregional constraint function to constrain the overestimation of the transmission in the flat region, thereby maintaining the consistency between the estimated transmission map and the depth map. The experimental results demonstrate that the proposed method can achieve natural defogging performance in terms of various foggy conditions.

Study of viable charged wormhole solutions in [formula omitted] theory

In this paper, we investigate how charge and modified terms affect the viability and stability of traversable wormhole geometry in the framework of f(R,G) theory, where R is the Ricci scalar and G is the Gauss–Bonnet term. For this purpose, we develop a shape function through the Karmarkar condition to examine the wormhole geometry. The resulting shape function satisfies all the necessary conditions and establishes a connection between the asymptotically flat regions of the spacetime. The behavior of energy conditions and sound speed is checked in the presence of higher-order curvature terms and electromagnetic field to analyze the existence of stable traversable wormhole geometry. It is found that the traversable wormhole solutions are viable and stable in this modified theory.

Unraveling the interplay between antibiotic resistance genes and microbial communities in water and sediments of the intensive tidal flat aquaculture

Tidal flats are formed valuably resources by the interaction of terrestrial and marine processes. Aquaculture on tidal flats has brought significant economic profits, but the over usage of antibiotics has resulted in the prevalence antibiotic resistance genes (ARGs) which pose serious threats to ecosystems. However, ARG abundances and bacterial community assemblies in the overlying water and sediments of tidal flat aquaculture areas have not been fully explored. Thus, antibiotic concentrations, ARG abundances, microbial communities and the influences of environmental factors in the Jiangsu tidal flat aquaculture ponds were investigated using high-throughput sequencing and qPCR. The concentrations of antibiotics at sampling ranged from not detectable to 2322.4 ng g−1, and sulfamethazine and ciprofloxacin were the dominant antibiotics. The sul1 and sul2 abundances were highest and the ARG abundances were higher in sediment than in water. Meanwhile, bacterial community diversities and structures were significantly different (P < 0.05) between water and sediment samples. Network analysis identified Sphingomonadacear, Pseudomonas, and Xanthobacteraceae as potential ARG-carrying pathogens. A positive correlation between ARGs and intI1 indicated that horizontal gene transfer occurred in water, while antibiotics and TN significantly influenced ARG abundances in sediment. Neutral modeling showed that deterministic and stochastic processes contributed most to the bacterial community assemblies of water and sediment samples, respectively. This study comprehensively illustrates the prevalence of ARGs in intensive tidal flat aquaculture regions and provides an effective foundation for the management of antibiotics usage.

Tidal energy extraction modifies tidal asymmetry and transport in a shallow, well-mixed estuary

Tidal energy extraction is increasingly being studied as a potential renewable energy resource in estuaries worldwide. Although it is understood that energy extraction via tidal stream turbines can modify currents and transport within estuaries, it is not clear how the underlying nonlinear physical mechanisms dictating tidal hydrodynamics are modulated. This research investigates the influence of a hypothetical tidal stream turbine array on barotropic tidal processes in a shallow, well-mixed system: the Piscataqua River – Great Bay (PRGB) estuary, using a numerical model. The modeled turbine farm includes 180 turbines which would extract an estimated 44.7 GWh of energy, annually. The tidal hydrodynamic model for the existing condition is validated with in-situ observations of currents and water level before analyzing tidal asymmetry and transport with and without tidal turbines. Results indicate that the tidal turbine array will decrease tidal elevation and current magnitudes system-wide, but generally reduce ebb currents and transport more than flood over most of the estuary footprint, thereby diminishing tidal asymmetry. The smaller asymmetric distortion compared to the no-turbine case is attributed to reductions in the storage volume of water over the estuary’s extensive tidal flat regions between low and high waters which decreases the associated nonlinear intertidal storage mechanism up to 25%. This leads to weakened ebb dominance over estuary sections from the mouth to mid-reaches, where depths are deep enough to keep the combined nonlinear shallow water and frictional effects from asserting control over the storage mechanism. Even in upstream shallow regions where depth-dependent friction controls asymmetry in both cases, the frictional mechanism is reduced only by 10% with turbines. Some environmental considerations of this work are discussed, with focus on sediment transport, water quality, and ecology.

Reversible adversarial steganography for security enhancement

In adaptive steganography, existing universal stego post-processing methods can enhance security, but suffer from incorrect extraction of messages and undesired visual defects, especially in flat regions. To address this issue, a reversible adversarial steganography method is proposed by modifying the LSB or 2ndLSB of stego-images, which has promising visual quality and security. To that end, the content-adaptive adversarial perturbations are first generated, which consider image texture with noise residual features to counter deep learning-based steganalyzers. Then, a data compression strategy of adversarial perturbations is designed by applying lossless run-length encoding based on the sparse nature of non-zero elements in the perturbations to reduce the perturbation’s quantity. Finally, reversible data hiding based on ternary coding is applied to embed and extract stego images with compressed adversarial perturbations. Extensive experimental results demonstrate that the proposed method can effectively enhance security and visual quality compared with state-of-the-art methods.

Regiospecific Cellulose Orientation and Anisotropic Mechanical Property in Plant Cell Walls.

Cellulose microfibrils (CMFs) are a major load-bearing component in plant cell walls. Thus, their structures have been studied extensively with spectroscopic and microscopic characterization methods, but the findings from these two approaches were inconsistent, which hampers the mechanistic understanding of cell wall mechanics. Here, we report the regiospecific assembly of CMFs in the periclinal wall of plant epidermal cells. Using sum frequency generation spectroscopic imaging, we found that CMFs are highly aligned in the cell edge region where two cells form a junction, whereas they are mostly isotropic on average throughout the wall thickness in the flat face region of the epidermal cell. This subcellular-level heterogeneity in the CMF alignment provided a new perspective on tissue-level anisotropy in the tensile modulus of cell wall materials. This finding also has resolved a previous contradiction between the spectroscopic and microscopic imaging studies, which paves a foundation for better understanding of the cell wall architecture, especially structure-geometry relationships.