Diagonal Region Research Articles

Experimental and numerical investigation of a double spiral tube heat exchanger in a novel composite phase change material

Phase change energy storage technology effectively harnesses energy, and phase change materials have been garnered significant attention due to their high latent heat capacity. The heat transfer capacity and phase transition of HCNT − CH3COONa·3H2O/Na2HPO4·12H2O composites in a double spiral tube heat storage unit were investigated. The effects of different flow rates and temperatures on the heat transfer characteristics of phase change materials were studied, and the thermal performance of the storage units was evaluated by calculating the power, energy and energy efficiency ratios. The phase change process of the composite during heat transfer was further revealed via simulation, and the heat storage and heat release of the composite were compared with those of other phase change materials. The results show that the effects of the flow velocity on the transformation time and power of the phase change material are negligible. However, an increase in flow rate can significantly increase the heat storage and heat release of the phase change unit. In particular, when the flow rate is 4 LPM, the energy efficiency ratio can reach 76.6 %. When the temperature increases from 80 °C to 90 °C, the melting time decreases by 30.23 %, indicating that increasing the temperature has a significant effect on the phase transition process. Through simulation calculations, the composite phase change material shows significant performance advantages under the same working conditions; its heat storage capacity is 108 % greater than that of the other materials, and the heat release capacity is 206 % greater, which indicates that it has greater energy storage and release efficiency and a better thermal energy conversion capacity. In addition, the experimental and simulation results also reveal the existence of a diagonal region of slow phase transition in the heat storage unit. In summary, this paper analyses the heat transfer performance of a double spiral tube heat storage device, provides a theoretical basis for practical application, and provides an important reference for improving the performance of a phase–change energy storage system.

DiagSWin: A multi-scale vision transformer with diagonal-shaped windows for object detection and segmentation

Recently, Vision Transformer and its variants have demonstrated remarkable performance on various computer vision tasks, thanks to its competence in capturing global visual dependencies through self-attention. However, global self-attention suffers from high computational cost due to quadratic computational overhead, especially for the high-resolution vision tasks (e.g., object detection and semantic segmentation). Many recent works have attempted to reduce the cost by applying fine-grained local attention, but these approaches cripple the long-range modeling power of the original self-attention mechanism. Furthermore, these approaches usually have similar receptive fields within each layer, thus limiting the ability of each self-attention layer to capture multi-scale features, resulting in performance degradation when handling images with objects of different scales. To address these issues, we develop the Diagonal-shaped Window (DiagSWin) attention mechanism for modeling attentions in diagonal regions at hybrid scales per attention layer. The key idea of DiagSWin attention is to inject multi-scale receptive field sizes into tokens: before computing the self-attention matrix, each token attends its closest surrounding tokens at fine granularity and the tokens far away at coarse granularity. This mechanism is able to effectively capture multi-scale context information while reducing computational complexity. With DiagSwin attention, we present a new variant of Vision Transformer models, called DiagSWin Transformers, and demonstrate their superiority in extensive experiments across various tasks. Specifically, the DiagSwin Transformer with a large size achieves 84.4% Top-1 accuracy and outperforms the SOTA CSWin Transformer on ImageNet with 40% fewer model size and computation cost. When employed as backbones, DiagSWin Transformers achieve significant improvements over the current SOTA modules. In addition, our DiagSWin-Base model yields 51.1 box mAP and 45.8 mask mAP on COCO for object detection and segmentation, and 52.3 mIoU on the ADE20K for semantic segmentation.

Structures and dynamics of 8-oxo-7,8-dihydro-2'-deoxyguanosine in neutral and basic aqueous solutions by spectroscopy.

8-oxo-7,8-dihydro-2'-dexyoguanine (8-oxo-dG) can be tautomerized to a 6-enolate,8-keto tautomer through nearby-NH deprotonation at elevated pH. In this work, the N3-protonated 8-oxo-dG tautomers in deuterated pH-buffer solutions were studied using steady-state UV/Vis, FTIR, and ultrafast two-dimensional IR spectroscopies. The presence of 6,8-diketo and C6-anionic tautomers at neutral to basic conditions (pD = 7.4-12.0) was revealed by UV/Vis and FTIR results and was further confirmed by 2D IR signals in both diagonal and off-diagonal regions. However, the C6-enol tautomer, which may be an intermediate during the transition from 6,8-diketo to C6-enolate,C8-keto, was not observed appreciably due to its extreme low population. Furthermore, the neutral-to-anionic tautomeric transition of N3H-8-oxo-dG studied in this work occurs under more basic conditions than the N1H-8-oxo-dG reported previously, showing a higher pKa value for N3H than N1H. Finally, vibrational relaxation of the carbonyl stretching mode was found to be both molecular site dependent and pD dependent for 8oxo-dG. Taken together, this work shows that the ultrafast infrared spectroscopic method is effective for examining tautomers and their dynamics in nucleic acids.

Molecular insight into the decomposition mechanism and stability of CO2 hydrate in the symmetric non-flat double-plate porous media system

Unveiling the decomposition mechanism and stability of hydrate in porous media sediments is the fundamental issue related to hydrate-based CO2 capture and sequestration. In this work, Molecular Dynamics (MD) simulations were performed to study the decomposition mechanism and stability of CO2 hydrate in the porous media of symmetric non-flat double-plate system and explore its mass transfer process. The model of CO2 hydrate in porous media possessing symmetric non-flat double-plate structure was constructed using square quartz (SiO2) as the single crystal material of porous media, illustrating the decomposition mechanism and stability law of CO2 hydrate in such media system. Simulation results indicate that there exists no pretty noteworthy discrepancy between CO2 hydrate in the symmetric non-flat double-plate porous media system and pure CO2 hydrate at the aspect of the decomposition process and sequence. The decomposition process can be divided into two stages: initial cage destruction and CO2 bubble evolution. The decomposition order proceeds in an outside to inside manner generally, with CO2 hydrate decomposition in the middle layer and diagonal region taking priority. Furthermore, the distance between media layers exerts a prominent influence on CO2 hydrate decomposition, which larger distance motivates the decomposition of CO2 hydrate easier. The results also indicated that, compared with pure water system, the stability of CO2 hydrate is greater in the symmetric non-flat double-plate porous media system, with the extreme values of DC reaching 0.64 times only than pure water system. Additionally, CO2 hydrate displayed a stronger stability in the confined space. These findings are beneficial for understanding the decomposition mechanism and stability of CO2 hydrate and provide an interesting insight into geological CO2 sequestration in sediments.

An efficient adaptive routing algorithm for the Co-optimization of fault tolerance and congestion awareness based on 3D NoC

In this paper, we propose an adaptive, fault-tolerant, and congestion-aware (AFTC) routing algorithm. It improves the overall network performance of three-dimensional Network-on-Chip (3D NoC) in terms of deadlock-free, adaptability, fault tolerance, and balanced traffic. Firstly, the algorithm proposed 12 turn models to avoid deadlock problems. Then, the adaptability of the algorithm is improved by using the three-dimensional diagonal region division method. At the same time, the AFTC can reduce the number of turn-around steps during fault tolerance. Finally, the AFTC can balance traffic by setting different congestion thresholds. Compared with Vertical-Mesh-Conscious-Dynamic (VMCD) algorithm in terms of average packet delay and throughput, the AFTC algorithm can improve the throughput by an average of 27.29 % and 18.62 % while reducing the average delay time in different fault rates under uniform traffic and hotspot traffic patterns, respectively.

Hybrid Sidelobe Recognition Method Using Boresight Error and Quadrant Signal Difference for Monopulse Array

In this paper, a sidelobe recognition method using boresight error and quadrant signal difference for a monopulse array is proposed. A conventional sidelobe recognition method compares the difference between the sum and delta channels. This method works well for the azimuth and elevation planes. However, the method is prone to many errors in the diagonal region of the two-dimensional plane. To overcome this problem, a method to calculate the deviation of the boresight error difference with different frequency combinations and a threshold to identify the sidelobe is proposed, and the method is validated to significantly reduce the error region. If a four-quadrant signal can be extracted separately, the signal deviation can be calculated and compared with the threshold, and the error region can be further reduced. The effects of each margin and bandwidth on the recognition performance are analyzed, and a slot array antenna is simulated to assess the method’s effectiveness.

Col-OSSOS: The Two Types of Kuiper Belt Surfaces

The Colors of the Outer Solar System Origins Survey (Col-OSSOS) has gathered a high-quality, near-simultaneous, and brightness-complete sample of (g − r) and (r − J) colors for 102 Kuiper Belt objects (KBOs) with (u − g) and (r − z) gathered for some. We present the current state of the survey and data analysis. Recognizing that the optical colors of most icy bodies broadly follow the reddening curve, we present a new projection of the optical−near-IR (NIR) colors, which rectifies the main nonlinear features in the optical−NIR along the ordinates. We find evidence for a bifurcation in the projected colors that presents itself as a diagonal empty region in the optical−NIR. A reanalysis of past color surveys reveals the same bifurcation. We interpret this as evidence for two separate surface classes: the BrightIR class spans the full range of optical colors and broadly follows the reddening curve, while the FaintIR objects are limited in optical color and are less bright in the NIR than the BrightIR objects. We present a two-class model. Objects in each class consist of a mix of separate blue and red materials and span a broad range in color. Spectra are modeled as linear optical and NIR spectra with different slopes that intersect at some transition wavelength. The underlying spectral properties of the two classes reproduce the main observed structures in the UV−optical−NIR color space (0.4 μm ≲ λ ≲ 1.4 μm), including the bifurcation observed in the Col-OSSOS and H/WTSOSS data sets, including the tendency for cold classical KBOs to have lower (r − z) colors than excited objects, and the well-known bimodal optical color distribution.

Prediction of shear strength for CFRP reinforced concrete beams without stirrups

Design guidelines in international codes show noticeable differences with regards to shear strength prediction of concrete beams reinforced with Fiber Reinforced Polymers, (FRP). These discrepancies in shear strength predictions are attributed to many factors affecting the shear behavior, such as shear span/depth ratio (a/d), beam size, rectangular and flanged cross-sectional shape (R-section and T-section), and concrete compressive strength. Shear resistance of beams longitudinally reinforced with carbon FRP, (CFRP), bars is not well defined in the literature compared to beams reinforced with steel bars. This is mainly attributed to the low modulus of elasticity of CFRP compared to traditional steel reinforcement resulting in relatively high strains generated in CFRP reinforcement and consequently wider cracks and lower contribution of the aggregate interlocking mechanism as well as dowel action in shear resistance. This paper numerically investigates the behavior of concrete beams reinforced in flexure with CFRP bars without transverse reinforcement to quantify concrete contribution in shear resistance. Specimens with R and T sections having different shear span-to-depth ratio, concrete compressive strength, and longitudinal CFRP reinforcement ratios are studied to determine the concrete contribution to shear resistance. The nonlinear program ATENA is used to simulate the actual behavior of concrete beams failing in shear and is verified against experimental results gathered from the literature to check the validity of the numerical model. The comparison shows good agreement between experimental and numerical results with a difference of 6% and then a parametric study is conducted to provide a better understanding of the effect of each parameter on the shear behavior of concrete beams reinforced with CFRP bars. The results of numerical models are compared to their counterparts predicted using different equations in codes and guidelines. It is found that the shear capacity of T-section is higher than R-section by about 15% to 25% mainly due to a change in cracking pattern due to the presence of the flange. Furthermore, the shear failure load increased by increasing the longitudinal reinforcement ratio as a result of decreasing strain and enhancement of dowel action. The effect of increasing concrete compressive strength was more pronounced on the shear capacity in arch action as opposed to diagonal tension regions. Finally, an equation is proposed to predict the shear capacity of concrete beams reinforced in flexure with CFRP bars. The shear capacity predicted by the proposed equation provided a good agreement with experimental results for 163 beams with a mean value of 1.01 and COV of 0.17.

Evaluation of multiple reanalyses in reproducing the spatio‐temporal variability of temperature and precipitation indices over southern South America

AbstractSeveral temperature and precipitation indices, with special focus on extremes, were analysed in different sub‐regions of southern South America during 1979–2017 using multiple reanalyses, the CPC gridded data set and the most extended network of meteorological stations employed in regional climate studies up to date. Reanalyses generally well represented the spatial patterns of the indices, although they showed some differences in extreme indices over large portions of southern South America and tended to overestimate precipitation maximums, especially in southern Chile. Furthermore, ERA‐Interim presented clear difficulties in reproducing precipitation near the Andes Mountains, exhibiting the largest overestimations. This seemed to be improved in the new generation of ERA reanalyses (ERA5). When evaluating the long‐term changes, most of the data sets agreed in general warming conditions, stronger and more homogeneous for the maximum temperature. NCEP1 and NCEP2 reanalyses showed contrary temporal changes in almost all the temperature indices. Precipitation indices exhibited less consistent changes among reanalyses, although significant upward trends were detected for precipitation extremes in southeastern South America and downward trends were detected in southern Chile in the observational data sets. In addition, most of the data sets agreed in drier conditions in the arid diagonal region of Argentina as reflected by significant positive trends for dry spells and negative trends for the total annual precipitation. In terms of the inter‐annual correspondence, reanalyses usually presented good correlations to the stations reference in the regional averaged series, mainly for temperature indices and more variable for precipitation indices. Overall, no reanalysis was found to perform best. The use of reanalyses data to perform regional climate studies should consider the existent differences among them and with observational data. Moreover, using multiple sources of information is strongly recommended to account for observational uncertainty, especially in regions like southern South America, where data availability and its resolution are often limited.

A WAVELET BASED COPYRIGHT MARKING ON IMAGE UNDER SUB-BANDS STACKING TECHNIQUE

Watermarking of multimedia gives more attention in research society. This paper presents the non-blind watermarking technique; initially a watermark is reshaped and grouped into odd and even row images. Next, two level decomposition is imposed on an original image and to enrich the robustness of the technique, divide LL2 in to two shares and stack with LH1. Copyright marking process is enabled in the lower diagonal regions of stacked sub-bands wavelet coefficients. Next, the merge sub-bands are back to the original position, inverse wavelet is imposed to obtain the marked cover image. To prove authorship the cover and copyrighted image has subject to the same procedure and acquires the marked information

Security enhancement in video based on gatefold technique for copyright protection

Watermarking of multimedia gives more attention to the research society. This paper presents the non-blind watermarking technique on video; initially, a watermark is reshaped and grouped into odd and even row images. Next, the luminance band of the frame is shared into alternative pixel shares and it is concatenated. Further, gatefold operation is enabled on a concatenated luminance band. Now, single-level decomposition is imposed on the gatefold image and, the copyright marking process is enabled only on the medium level of frequency sub-bands. To enrich the robustness of the technique the marking fashion is in the upper diagonal layer region of wavelet sub-band. Next, an inverse wavelet is imposed to obtain the gate folded marked cover image. Further, the reverse process can be carried out to obtain the watermarked video frame. To prove authorship the cover and copyrighted image has subject to the same procedure and acquires the marked information. The main objective is to design and develop a gatefold based video authentication approaches with ownership information that can be used for copyright protection. Also increase the robustness, payload, and minimize the bit error rate.

A Novel Diagonal Class Entropy-Based Multilevel Image Thresholding Using Coral Reef Optimization

In the normal image thresholding methods based on two-dimensional histogram, the edge information of the regions is not maintained because of the local averaging activity used. Moreover, the computation time increases with the increase in the level of thresholds. This paper focusses on retaining more edge information by calculating the image entropy along the diagonal regions of the gray level co-occurrence matrix inspired from the partitioned design structure matrix, which is a novel idea. In addition, the key to our success is the theoretical investigation of a novel diagonal class entropy (DCE) concept that utilizes the minimum area for computation. The benefits of the proposed method are: 1) improved results; 2) efficient to preserve more precise shape of the edges; and 3) the computation time decreases with the increase in the threshold levels. The optimal thresholds are obtained by minimizing the DCE using coral reef optimization (CRO). A first hand fitness function for multilevel image thresholding is derived. The fight for space and the efficient reproduction characteristics of the CRO makes it attractive for this application. Benchmark images from the Berkley segmentation dataset are taken to experiment. Our results are compared with other state-of-the-art thresholding methods. The results obtained are encouraging and may set the path for further investigation in the domain of multilevel thresholding.

SOLVING DIAGONAL SUDOKU PUZZLE 9X9 GRID BY JAVA PROGRAMMING ALGORITHM

Sudoku is one of the well-known puzzle game that has been played worldwide. There are many types of Sudoku puzzle that exist to be played such as diagonal, diagonal even, diagonal odd, is sudoku, lucky seven, parquet and others. This paper focuses on solving the diagonal Sudoku by using Java Programming Algorithm for 9x9 grid. For normal Sudoku, the number 1-9 must be filled up in all grids with no number duplication conflict in the row, column and 3x3 grid inside the Sudoku puzzle itself. While the diagonal Sudoku has one extra condition to be considered that is the number 1-9 must also be filled in the diagonal place which starts from the most upper-left or bottom-left to the most upper-right or bottom-right of the puzzle. There is no conflict with other grid in its diagonal region. In order to solve the puzzle, we have to construct an algorithm and translate it using Java Programming Language. The guessing method with backtrack approach has been selected to construct the algorithm. This Java Programming is designed to solve the diagonal Sudoku puzzle for a 9x9 grid.

Modeling Methods for Collapse Analysis of Reinforced Concrete Frames with Infill Walls

Progressive collapse behavior of RC infilled frames is studied experimentally under quasi-static loading and numerically by using macro (strut) and micro (finite-element) models to simulate the damage propagation within infill walls. A three-strut model is proposed to simulate the overall behavior of infill walls based on the observation that corner regions of infill walls play an important role even after the cracking of the diagonal region in infill walls. The proposed three-strut model is implemented using commercially available software. The accuracy of the proposed method is evaluated by comparing the experimental data with simulated responses from detailed finite-element models and simplified strut models. The modified three-strut model is also compared with other widely used strut models. The comparison shows that the proposed three-strut model predicts the maximum resistance force with higher accuracy. Finally, a simpler model is developed based on the proposed three-strut model for infill walls. This simpler model can easily be implemented by practicing engineers to predict the overall behavior of the infilled frame with acceptable accuracy.

Cross-Layered Embedding of Watermark on Image for High Authentication

Watermarking on multimedia gives more attention in research society. In this non-blind watermarking approach a watermark is reshaped and grouped into odd and even images. Next, wavelet is imposed on an original image and to enrich the robustness of the technique, watermarking process is enabled only in the upper diagonal regions of middle level wavelet coefficients. Further, the backward process is taken place to obtain the watermarked image. To prove ownership, original and watermarked image have undergone the same operation and acquire the copyright information. Experimental results indicate that the quality of the watermarked image is better also this algorithm is robust against filtering and geometrical attacks.

Polarization Reconfigurable Square Patch Antenna for Wireless Communications

In this paper, a single fed polarization reconfigurable antenna is proposed. The antenna consists of a radiating patch incorporated with a diagonal-shaped slot at its center. Four p-i-n diodes are used for polarization reconfiguration. The p-i-n diodes are placed in diagonal slot region. The proposed antenna is designed to operate in three states – linear polarization (LP), left-hand circular polarization (LHCP) and right-hand circular polarization (RHCP) by biasing corresponding p-i-n diodes. The antenna gives measured peak gain of 6.2 dBi for LP state and 5.82 dBic for both RHCP and LHCP states. It also achieves 3-dB axial ratio bandwidth of 5.95% for both RHCP and LHCP configurations. The antenna finds application in areas of modern wireless communication.

Ground- and Excited-State Interactions of a Psoralen Derivative with Human Telomeric G-Quadruplex DNA.

G-quadruplex DNA has been a recent target for anticancer agents, and its binding interactions with small molecules, often used as anticancer drugs, have become an important area of research. Considering that psoralens have long been studied in the context of duplex DNA but that very little is known about their potential as G-quadruplex binders and their excited-state interaction with the latter has not been explored, we have studied herein the binding of a planar water-soluble psoralen derivative, 4'-aminomethyl-4,5',8-trimethylpsoralen (AMT), with the 22-mer human telomeric G-quadruplex-forming sequence, AGGG(TTAGGG)3, labeled here as (hTel22), and investigated the consequences of photoexcitation of AMT by calorimetric and spectroscopic techniques. The results show an enthalpy-driven 1:1 binding of AMT with hTel22 via end-stacking mode. Fluorescence quenching experiments on 6-fluorescein amidite-labeled oligomers indicate that the binding site is nearer to the 3' end of hTel22 in the diagonal loop region. Femtosecond time-resolved transient absorption measurements indicate electron transfer from the guanine moiety of hTel22 to photoexcited AMT, leading to the formation of a radical pair species (AMT•-G•+), which survives for 30 ps and is favored by a parallel/quasi-parallel orientation between the two. The findings reveal psoralens as a prospective class of compounds for the development of anticancer therapeutics by targeting the G-quadruplex DNA.

A parallelizable direct solution of integral equation methods for electromagnetic analysis

A parallelizable direct solution of integral equation methods is proposed for electromagnetic scattering analysis in low to intermediate frequency regime. There are mainly two parts of the proposed direct solution: forward decomposition and backward substitution. For the forward decomposition, the dense impedance matrix is decomposed of the product of several block diagonal matrices implicitly, which is shown to be O(Nlog2N) for both memory and CPU time cost. The final solutions are obtained with several matrix vector products (MVPs) in the part of backward substitution with O(Nlog2N) complexity as well. Both forward decomposition and backward substitution can be parallelized because of the group independence. Furthermore, an effective preconditioner with a reasonable selection criterion of the diagonal blocks region is proposed to accelerate the convergence of the iterative solver. The proposed solution is independent of the Green's function, and it is suitable for all the integral equation methods. Without loss of generality, the solution is proposed to solve the electric field integral equation (EFIE) in this work. Numerical tests demonstrate the effectiveness of the proposed solution for the electromagnetic analysis, especially for multiscale structures.

Covariance J-resolved spectroscopy: Theory and application in vivo.

Magnetic resonance spectroscopy (MRS) is a powerful tool capable of investigating the metabolic status of several tissues in vivo. In particular, single-voxel-based 1 H spectroscopy provides invaluable biochemical information from a volume of interest (VOI) and has therefore been used in a variety of studies. Unfortunately, typical one-dimensional MRS data suffer from severe signal overlap and thus important metabolites are difficult to distinguish. One method that is used to disentangle overlapping resonances is the two-dimensional J-resolved spectroscopy (JPRESS) experiment. Due to the long acquisition duration of the JPRESS experiment, a limited number of points are acquired in the indirect dimension, leading to poor spectral resolution along this dimension. Poor spectral resolution is problematic because proper peak assignment may be hindered, which is why the zero-filling method is often used to improve resolution as a post-processing step. However, zero-filling leads to spectral artifacts, which may affect visualization and quantitation of spectra. A novel method utilizing a covariance transformation, called covariance J-resolved spectroscopy (CovJ), was developed in order to improve spectral resolution along the indirect dimension (F1 ). Comparison of simulated data demonstrates that peak structures remain qualitatively similar between JPRESS and the novel method along the diagonal region (F1 = 0 Hz), whereas differences arise in the cross-peak (F1 ≠0 Hz) regions. In addition, quantitative results of in vivo JPRESS data acquired on a 3T scanner show significant correlations (r2 >0.86, p<0.001) when comparing the metabolite concentrations between the two methods. Finally, a quantitation algorithm, 'COVariance Spectral Evaluation of 1 H Acquisitions using Representative prior knowledge' (Cov-SEHAR), was developed in order to quantify γ-aminobutyric acid and glutamate from the CovJ spectra. These preliminary findings indicate that the CovJ method may be used to improve spectral resolution without hindering metabolite quantitation for J-resolved spectra.

Multihole edge states in Su-Schrieffer-Heeger chains with interactions

We address the effect of nearest-neighbor (NN) interactions on the topological properties of the Su-Schrieffer-Heeger (SSH) chain, with alternating hopping amplitudes t1 and t2. Both numerically and analytically, we show that the presence of interactions induces phase transitions between topologically different regimes. In the particular case of one-hole excitations in a half-filled SSH chain, the V=t2 vs. t1=t2 phase diagram has topological phases at diagonal regions of the phase plane. The interaction acts in this case as a passivation potential. For general filling of the SSH chain, different eigensubspaces of the SSH Hamiltonian may be classified as topologically trivial and non-trivial. The two-hole case is studied in detail in the large interaction limit, and we show that a mapping can be constructed of the two-hole SSH eigensubspaces into one-particle states of a non-interacting one-dimensional (1D) tight-binding model, with interfaces between regions with different hopping constants and local potentials. The presence of topological edge states in the equivalent chain can be readily identifed, as well as their correspondence to the original two-hole states. Furthermore, we found that the presence of the NN interaction generates a state where two holes occupy two consecutive edge states. Such many-body states should also occur for arbitrary filling leading to the possibility of a macroscopic hole gathering at the surface (at consecutive edge states).