Evaluation and Research Analysis of Marine Ecological Suitability

Whether in the past, present and future, marine ecological environment is the most important part in the history of human development, we can call it the "patron saint" of mankind. It provides all kinds of resources and energy needed for social production, and plays an irreplaceable role in species diversity and ecological balance. However, the weakening of self-purification ability of marine ecosystem, the decline of pollution purification ability, the deterioration of marine ecological environment, and the decline of biological resources and biodiversity ,etc. all these bring fatal impact to coastal areas and even the whole terrestrial ecosystem, it is imminent to strengthen ecological protection. It is our bounden duty to protect the living environment of human. We have the right to enjoy the convenience brought by the natural environment, so we should fulfill the obligation to protect it.[Chinese Library Classification Number]   X31        [Document Code]  

Differences in structural connectivity between diabetic and psychological erectile dysfunction revealed by network-based statistic: A diffusion tensor imaging study

IntroductionType 2 diabetes mellitus (T2DM) has been found to be associated with abnormalities of the central and peripheral vascular nervous system, which were considered to be involved in the development of cognitive impairments and erectile dysfunction (ED). In addition, altered brain function and structure were identified in patients with ED, especially psychological ED (pED). However, the similarities and the differences of the central neural mechanisms underlying pED and T2DM with ED (DM-ED) remained unclear.MethodsDiffusion tensor imaging data were acquired from 30 T2DM, 32 ED, and 31 DM-ED patients and 47 healthy controls (HCs). Then, whole-brain structural networks were constructed, which were mapped by connectivity matrices (90 × 90) representing the white matter between 90 brain regions parcellated by the anatomical automatic labeling template. Finally, the method of network-based statistic (NBS) was applied to assess the group differences of the structural connectivity.ResultsOur NBS analysis demonstrated three subnetworks with reduced structural connectivity in DM, pED, and DM-ED patients when compared to HCs, which were predominantly located in the prefrontal and subcortical areas. Compared with DM patients, DM-ED patients had an impaired subnetwork with increased structural connectivity, which were primarily located in the parietal regions. Compared with pED patients, an altered subnetwork with increased structural connectivity was identified in DM-ED patients, which were mainly located in the prefrontal and cingulate areas.ConclusionThese findings highlighted that the reduced structural connections in the prefrontal and subcortical areas were similar mechanisms to those associated with pED and DM-ED. However, different connectivity patterns were found between pED and DM-ED, and the increased connectivity in the frontal–parietal network might be due to the compensation mechanisms that were devoted to improving erectile function

Multi-Channel Deconvolution for Forward-Looking Phase Array Radar Imaging

The cross-range resolution of forward-looking phase array radar (PAR) is limited by the effective antenna beamwidth since the azimuth echo is the convolution of antenna pattern and targets’ backscattering coefficients. Therefore, deconvolution algorithms are proposed to improve the imaging resolution under the limited antenna beamwidth. However, as a typical inverse problem, deconvolution is essentially a highly ill-posed problem which is sensitive to noise and cannot ensure a reliable and robust estimation. In this paper, multi-channel deconvolution is proposed for improving the performance of deconvolution, which intends to considerably alleviate the ill-posed problem of single-channel deconvolution. To depict the performance improvement obtained by multi-channel more effectively, evaluation parameters are generalized to characterize the angular spectrum of antenna pattern or singular value distribution of observation matrix, which are conducted to compare different deconvolution systems. Here we present two multi-channel deconvolution algorithms which improve upon the traditional deconvolution algorithms via combining with multi-channel technique. Extensive simulations and experimental results based on real data are presented to verify the effectiveness of the proposed imaging methods

Echo Preprocessing to Enhance SNR for 2D CS-Based ISAR Imaging Method

A new CS-based inverse synthetic aperture radar (ISAR) imaging framework is proposed to enhance both the image performance and the robustness at a low SNR. An ISAR echo preprocessing method for enhancing the ISAR imaging quality of compressed sensing (CS) based algorithms is developed by implementing matched filtering, echo denoising and matrix optimization sequentially. After the preprocessing, the two-dimensional (2D) SL0 algorithm is applied to reconstruct an ISAR image in the range and cross-range plane through a series of 2D matrices using the 2D CS theory, rather than converting the 2D convex optimization problem to the one-dimensional (1D) problem in the image reconstruction process. The proposed preprocessing framework is verified by simulations and experiment. Simulations and experimental results show that the ISAR image obtained by the 2D sparse recovery algorithm with our proposed method has a better performance

High Resolution Turntable Radar Imaging via Two Dimensional Deconvolution with Matrix Completion

Resolution is the bottleneck for the application of radar imaging, which is limited by the bandwidth for the range dimension and synthetic aperture for the cross-range dimension. The demand for high azimuth resolution inevitably results in a large amount of cross-range samplings, which always need a large number of transmit-receive channels or a long observation time. Compressive sensing (CS)-based methods could be used to reduce the samples, but suffer from the difficulty of designing the measurement matrix, and they are not robust enough in practical application. In this paper, based on the two-dimensional (2D) convolution model of the echo after matched filter (MF), we propose a novel 2D deconvolution algorithm for turntable radar to improve the radar imaging resolution. Additionally, in order to reduce the cross-range samples, we introduce a new matrix completion (MC) algorithm based on the hyperbolic tangent constraint to improve the performance of MC with undersampled data. Besides, we present a new way of echo matrix reconstruction for the situation that only partial cross-range data are observed and some columns of the echo matrix are missing. The new matrix has a better low rank property and needs just one operation of MC for all of the missing elements compared to the existing ways. Numerical simulations and experiments are carried out to demonstrate the effectiveness of the proposed method

Electrical-Elastic Joint Inversion Method for Fracture Characterization in Anisotropic Media

Fracture networks are omnipresent in unconventional energy reservoirs. The inversion of fractures is of vital importance to oil and gas exploration and production. Most of the existing inversion methods are developed based on homogeneous media theory and rely on a solitary physical descriptor. For instance, one commonly employed single-property inversion approach is the determination of water saturation through the use of the media's electrical conductivity. With the fast development of multiphysics geological survey, a joint inversion framework that is suitable for anisotropic fractured media is needed. In this article, we propose an electrical-elastic joint inversion method involving both electrical tensor and elastic tensor to invert the fracture characteristics (e.g., fracture shape, inclination angle, and porosity). We conduct numerical experiments with two-phase geometries containing idealized ellipsoidal fractures. The resistivity tensor and Young's moduli of different directions are calculated and used to construct an anisotropy diagram and a joint inversion chart. The method is validated by comparing the predicted fracture geometry with the actual geometry of the fracture embedded in media. Both ideal homogeneous media and digital rock samples are used to test the inversion framework. A comparison between the single- and the joint-property inversion is also presented, and the joint-property inversion shows a higher accuracy in predicting fracture volume and tilting angle. This work indicates that the proposed electrical-elastic joint method can capture the anisotropy of the formation rock, and the multiphysics inversion framework exhibits the potential to recover fracture features with high fidelity

A Fast and Accurate Sparse Continuous Signal Reconstruction by Homotopy DCD with Non-Convex Regularization

In recent years, various applications regarding sparse continuous signal recovery such as source localization, radar imaging, communication channel estimation, etc., have been addressed from the perspective of compressive sensing (CS) theory. However, there are two major defects that need to be tackled when considering any practical utilization. The first issue is off-grid problem caused by the basis mismatch between arbitrary located unknowns and the pre-specified dictionary, which would make conventional CS reconstruction methods degrade considerably. The second important issue is the urgent demand for low-complexity algorithms, especially when faced with the requirement of real-time implementation. In this paper, to deal with these two problems, we have presented three fast and accurate sparse reconstruction algorithms, termed as HR-DCD, Hlog-DCD and Hlp-DCD, which are based on homotopy, dichotomous coordinate descent (DCD) iterations and non-convex regularizations, by combining with the grid refinement technique. Experimental results are provided to demonstrate the effectiveness of the proposed algorithms and related analysis

The Effect of Bottom Ash Ball-Milling Time on Properties of Controlled Low-Strength Material Using Multi-Component Coal-Based Solid Wastes

As the conventional disposal method for industrial by-products and wastes, landfills can cause environmental pollution and huge economic costs. However, some secondary materials can be effectively used to develop novel underground filling materials. Controlled low-strength material (CLSM) is a highly flowable, controllable, and low-strength filling material. The rational use of coal industry by-products to prepare CLSM is significant in reducing environmental pollution and value-added disposal of solid waste. In this work, five different by-products of the coal industry (bottom ash (BA), fly ash, desulfurized gypsum, gasification slag, and coal gangue) and cement were used as mixtures to prepare multi-component coal industry solid waste-based CLSM. The microstructure and phase composition of the obtained samples were analyzed by scanning electron microscopy and X-ray diffraction. In addition, the particle size/fineness of samples was also measured. The changes in fresh and hardened properties of CLSM were studied using BA after ball milling for 20 min (BAI group) and 45 min (BAII group) that replaced fly ash with four mass ratios (10 wt%, 30 wt%, 50 wt%, and 70 wt%). The results showed that the CLSM mixtures satisfied the limits and requirements of the American Concrete Institute Committee 229 for CLSM. Improving the mass ratio of BA to fly ash and the ball-milling time of the BA significantly reduced the flowability and the bleeding of the CLSM; the flowability was still in the high flowability category, the lowest bleeding BAI70 (i.e., the content of BA in the BAI group was 70 wt%) and BAII70 (i.e., the content of BA in the BAII group was 70 wt%) decreased by 48% and 64%, respectively. Furthermore, the 3 d compressive strengths of BAI70 and BAII70 were increased by 48% and 93%, respectively, compared with the group without BA, which was significantly favorable, whereas the 28 d compressive strength did not change significantly. Moreover, the removability modulus of CLSM was calculated, which was greater than 1, indicating that CLSM was suitable for structural backfilling that requires a certain strength. This study provides a basis for the large-scale utilization of coal industry solid waste in the construction industry and underground coal mine filling

Cellulose Dissolution in a Mixed Solvent of Tetra(<i>n</i>‑butyl)ammonium Hydroxide/Dimethyl Sulfoxide via Radical Reactions

9.19 wt % of microcrystalline cellulose (MCC) could be dissolved in a new mixed solvent of tetra­(<i>n</i>-butyl)­ammonium hydroxide (TBAH; 20 wt %) and dimethyl sulfoxide (DMSO; 80 wt %) within 5 min at room temperature. The ratio of TBAH in the mixed solvent (<i>W</i>_TBAH) is found to exert great influence on the solubility of cellulose. Dissolution mechanism relative to radical reactions has been proposed according to electron spin resonance (ESR) and UV–vis results, showing positive correlation between cellulose solubility and the radical amount produced in the mixed solvent (i.e., <i>W</i>_TBAH). Partial degradation of the reducing AGU terminals via radical attack could be observed, followed by recombination of cellulose chain radicals, resulting in amorphous structures of all regenerated cellulose with higher average degree of polymerization values. Therefore, dissolution mechanism with regard to radical reactions has been proposed in this letter, supplementing the predominant electron donor–acceptor complexation theory