The prediction and control of enterprise financial risk is an important research topic in the financial field. Over the years, the financial risks of enterprises have seriously affected the healthy ...development of enterprises, credit institutions, securities investors and even the whole country. However, from the current practice and theoretical research of enterprises, how to effectively evaluate and control the financial risk of Chinese enterprises is still very scarce. Therefore, this paper conducts detailed analysis on the prediction and control of financial risk based on regression analysis to better identify the financial risks of enterprises.
The polymer membranes with super-wetting surface have shown promising application for oily wastewater treatment. However, the synergistic separation of multi-component oily wastewater in harsh ...environments is still a big challenge. In this work, we demonstrated a facile strategy to construct the durable super-hydrophilic/underwater super-oleophobic PEN composite membrane for the synergistic treatment of oil-in-water emulsions and dye. First of all, based on the thermally stable carboxyl poly (aryl ether nitrile), the hydrophilic polymer membrane with rough trench surface was prepared by non-solvent phase conversion, using non-woven fabric (NWF) as template. Secondly, the TiO2 nanoparticles were firmly immobilized onto the membrane surface via biomimetic co-deposition of dopamine (DA), aminopropyltriethoxysilane (APTES), and TiO2 nanoparticles. Especially, the physical confinement effect of rough trench surface, strong adhesion of polydopamine, and chemical crosslinking between APTES and DA contributed to the stable super-wetting performance of composite membrane (CA: 0° and UOC: 151°). Meanwhile, the obtained super-wetting composite membrane exhibited promising synergistic separation performance of multi-component oily wastewater (oil-in-water emulsions and dye). For the separation of oil-in-water emulsions containing 50 ppm methylene blue, the flux and rejection ratio reached 552.25 ± 25 L/(m2 h) and 99.38 ± 1.3%, respectively. More importantly, the prepared composite membrane could keep stable super-wetting property and separation efficiency under high-temperature and corrosive environments (80 °C/4 M HCl and 80 °C/1 M NaOH). In addition, the low oil adhesion and high tensile strength endowed the composite membrane with high antifouling resistance and excellent recyclability for the separation of multi-component oily wastewater. This work provides an alternative platform for constructing durable super-wetting composite membrane, which shows the potential application for treating complicated oily wastewater of petro-chemistry industry in harsh environments.
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•A novel super-wetting poly(arylene ether nitrile) composite membrane was designed.•The biomimetic co-deposition was developed for constructing super-hydrophilic/underwater super-oleophobic membrane surface.•The membrane exhibited promising synergistic separation for dye and various oil-in-water emulsions.•The membrane kept stable super-wetting - and separation -performance in high-temperature strongly corrosive environments.
Holes and inclusions can significantly affect the mechanical properties and fracture modes of brittle rocks. This study adopted digital image correlation (DIC), grain-based model, elastic mechanics ...and complex function theory to investigate the influence of hole shape, filling material stiffness and contact surface properties on the mechanical responses and fracture behaviors of granite. The results demonstrated that the macrocracks included primary tensile cracks, secondary or remote cracks and sidewall slabbing fractures. The uniaxial compressive strength (UCS) and local stress drops during the damage and failure stages changed with the shape of the hole or inclusion. Filling material effectively mitigated the stress concentration around the hole, and enhanced the UCS and elastic modulus. The filling material significantly affected the failure modes of the samples, and the rigid material improved the structural integrity of the damaged samples. Moreover, the friction coefficient of the contact surface and the elastic modulus of the inclusion improved the UCS, but the strengthening effects were limited.
The east-west ridge orientation has recently become an important agronomic method to improve mechanization in solar greenhouses. However, these ridge orientation changes shape differences between ...different ridges in crop water consumption, and there is a lack of research on the regulation and adaptation of water consumption. Therefore, this study introduces a variable irrigation decision-making method based on the Internet of Things management and control system for an east-west ridge orientation. To replenish water on demand, this study seting the variable irrigation decision-making (VRI) methods and traditional average irrigation decision-making (URI) methods in the system, and lettuce cultivation experiments were conducted to verify the effectiveness of the model and system. The results show that the difference of accumulated photosynthetically active radiation is the most significant between different ridges of the east-west ridge orientation, and the coefficient of variation is 43.77 %, which can be used as an activating factor for VRI methods. The irrigation water consumption, yield, water-use efficiencies, and irrigation water utilization of lettuce at different levels of irrigation were 307.12 L/m
, 5854.07 kg·ha
, 1391.47 kg·ha
·mm
, and 7.63 kg·cm
, respectively. Compared with the URI methods, the VRI method saved 10.02 % of water, increased yield by 9 %, and enhanced water use efficiency and irrigation water use efficiency by 12 % and 21.32 %, respectively. This study provides a new approach for improving crop production efficiency under an east-west ridge orientation.
Granite exhibits obvious meso-geometric heterogeneity. To study the influence of grain size and preferred grain orientation on the damage evolution and mechanical properties of granite, as well as to ...reveal the inner link between grain size‚ preferred orientation, uniaxial tensile strength (UTS) and damage evolution, a series of Brazilian splitting tests were carried out based on the combined finite-discrete element method (FDEM), grain-based model (GBM) and inverse Monte Carlo (IMC) algorithm. The main conclusions are as follows: (1) Mineral grain significantly influences the crack propagation paths, and the GBM can capture the location of fracture section more accurately than the conventional model. (2) Shear cracks occur near the loading area, while tensile and tensile-shear mixed cracks occur far from the loading area. The applied stress must overcome the tensile strength of the grain interface contacts. (3) The UTS and the ratio of the number of intergrain tensile cracks to the number of intragrain tensile cracks are negatively related to the grain size. (4) With the increase of the preferred grain orientation, the UTS presents a “V-shaped” characteristic distribution. (5) During the whole process of splitting simulation, shear microcracks play the dominant role in energy release; particularly, they occur in later stage. This novel framework, which can reveal the control mechanism of brittle rock heterogeneity on continuous-discontinuous trans-scale fracture process and microscopic rock behaviour, provides an effective technology and numerical analysis method for characterizing rock meso-structure. Accordingly, the research results can provide a useful reference for the prediction of heterogeneous rock mechanical properties and the stability control of engineering rock masses.
In this paper, the graphene oxide loaded with nano titanium dioxide (TiO
-GO) was synthesized through 3-isocyanatopropyltrimethoxysilane (IPTMS) and characterized by Fourier transform infrared ...spectroscopy (FTIR), X-ray diffraction analysis (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and dispersion test. The results illustrated our modification was successful and TiO
-GO was transferred from hydrophilic to hydrophobic. That greatly enhanced the dispersity of TiO
-GO in epoxy through the observation of the coating morphology test. Moreover, the impact of TiO
-GO on anti-corrosion property in epoxy was investigated by Electrochemical Impedance Spectroscopy (EIS). Comparing to pristine particles including GO and TiO
, TiO
-GO could more significantly improve the resistance of corrosion with the help of IPTMS. Furthermore, the anti-corrosion mechanism of TiO
-GO in epoxy was tentatively proposed and discussed.
In this paper, we consider Power Line Communications (PLC) for Smart Grid (SG) using Multiple-Input Multiple-Output and Orthogonal Frequency Division Multiplexing (MIMO-OFDM). We investigate a ...<inline-formula> <tex-math notation="LaTeX">2\times 2 </tex-math></inline-formula> MIMO-OFDM system and propose a novel nonzero comb pilot (NZCP) design for channel estimation that can cope with pilot contamination without the need for zero-pilot insertion in adjacent channels. The Bit Error Rate (BER) performance vs. <inline-formula> <tex-math notation="LaTeX">E_{b}/N_{0} </tex-math></inline-formula> is demonstrated using numerical simulations for uncoded and coded systems using Low Parity Density Check (LDPC) error correcting codes. The performance is compared with conventional Zero-comb pilot (ZCP) and the block pilot methods through frequency-selective multipath PLC channels and in the presence of Additive White Gaussian Noise (AWGN) and symmetric <inline-formula> <tex-math notation="LaTeX">\alpha </tex-math></inline-formula>-stable (<inline-formula> <tex-math notation="LaTeX">\text{S}\alpha \text{S} </tex-math></inline-formula>) type of impulsive noise. Additionally, a novel averaging method is introduced to reduce the effects of AWGN, <inline-formula> <tex-math notation="LaTeX">\text{S}\alpha \text{S} </tex-math></inline-formula> and Mean Square Error (MSE) metric is used to assess the quality of the channel estimation. The numerical results presented demonstrate that the NZCP approach using averaging outperforms all the methods considered, e.g. for the uncoded system at a BER of <inline-formula> <tex-math notation="LaTeX">10^{-5} </tex-math></inline-formula> an improvement in <inline-formula> <tex-math notation="LaTeX">E_{b}/N_{0} </tex-math></inline-formula> of 3.6 and 4 dB against ZCP and block approaches, respectively. In contrast, in the coded system, the coding gain is of the order of 20 dB compared to the uncoded cases with the NZCP proposed method outperforming all the other considered approaches by at least 0.5 dB. Furthermore, the presented BER results demonstrate that the <inline-formula> <tex-math notation="LaTeX">\text{S}\alpha \text{S} </tex-math></inline-formula> impulsive noise has a greater impact on the performance of the MIMO-PLC system. It is shown that when utilizing a hardlimiter to limit the effects of <inline-formula> <tex-math notation="LaTeX">\text{S}\alpha \text{S} </tex-math></inline-formula>, the BER can reach <inline-formula> <tex-math notation="LaTeX">8\times 10^{-5} </tex-math></inline-formula> at an <inline-formula> <tex-math notation="LaTeX">E_{b}/N_{0} </tex-math></inline-formula> of 45 dB when <inline-formula> <tex-math notation="LaTeX">\alpha =1.5 </tex-math></inline-formula>. In contrast, when <inline-formula> <tex-math notation="LaTeX">\alpha =1 </tex-math></inline-formula>, which represents a more severe case of <inline-formula> <tex-math notation="LaTeX">\text{S}\alpha \text{S} </tex-math></inline-formula>, a BER level of <inline-formula> <tex-math notation="LaTeX">3.5\times 10^{-4} </tex-math></inline-formula> is attained at an <inline-formula> <tex-math notation="LaTeX">E_{b}/N_{0} </tex-math></inline-formula> of 90 dB. However, the proposed averaging-NZCP system can robustly estimate the channel frequency responses (CFR) of the MIMO-PLC channel over <inline-formula> <tex-math notation="LaTeX">\text{S}\alpha \text{S} </tex-math></inline-formula> noise outperforming other commonly used pilot approaches.
Dynamics of a general jerky equation Tang, Diandian; Zhang, Shirui; Ren, Jingli
Journal of vibration and control,
02/2019, Letnik:
25, Številka:
4
Journal Article
Recenzirano
Some classic nonlinear dynamical systems, such as Rössler's toroidal model, the Genesio model, and 19 Sprott's models, can be classified into seven distinct basic classes of jerky dynamics, labeled ...by
J
D
1
-
J
D
7
. This paper is devoted to the dynamics of a general jerky equation which contains
J
D
1
-
J
D
7
as parameters vary. It is shown that the system undergoes fold, Hopf, zero-Hopf, and Bogdanov–Takens bifurcations based on the center manifold theorem and normal form theory. Numerical simulations are also given to make the theoretical results visible and to detect more complicated dynamical behaviors, including degenerate Hopf bifurcation, fold bifurcation of cycle, and limit cycles. Especially, an apple-like attractive portrait is discovered near the zero-Hopf bifurcation point for the first time. Finally, according to the conclusions of the general jerky equation, exact conditions are summarized by two tables on how bifurcations will occur for
J
D
1
-
J
D
7
, respectively.
The growth and yield of crops are highly dependent on irrigation. Implementing irrigation plans that are tailored to the specific water requirements of crops can enhance crop yield and improve the ...quality of tomatoes. The mastery and prediction of transpiration rate (Tr) is of great significance for greenhouse crop water management. However, due to the influence of multiple environmental factors and the mutual coupling between environmental factors, it is challenging to construct accurate prediction models. This study focuses on greenhouse tomatoes and proposes a data-driven model configuration based on the Competitive adaptive reweighted sampling (CARS) algorithm, using greenhouse environmental sensors that collect six parameters, such as air temperature, relative humidity, solar radiation, substrate temperature, light intensity, and CO2 concentration. In response to the differences in crop transpiration changes at different growth stages and time stages, the t-Distributed Stochastic Neighbor Embedding (t-SNE) algorithm was used to identify three characteristic intervals: florescence stage, fruiting stage daytime, and fruiting stage night-time. Based on this, a greenhouse tomato Tr prediction model (CARS-CatBoost model) based on the CatBoost machine learning algorithm was constructed. The experimental verification shows that the coefficient of determination (R2) of the constructed CARS-CatBoost single model for the whole growth stage is 0.92, which is higher than the prediction accuracy of the traditional single crop coefficient model (R2 = 0.54). Among them, the prediction accuracy at night during the fruiting stage is the highest, and the Root Mean Square Error (RMSE) drops to 0.427 g·m−2·h−1. This study provides an intelligent prediction method based on the zonal modeling of crop growth characteristics, which can be used to support precise irrigation regulation of greenhouse tomatoes.
Spiral phase plate (SPP) is the widely used method in the generation of vortex beam (VB) with fixed topological charges (TCs) for specific wavelength. Although VB with large TCs can be directly ...generated by using the SPP with high vortex order. The fabrication of high-quality SPPs with high vortex orders usually requires complex manufacturing process and high machining accuracy. An alternative method to generate VBs with large TCs is cascaded multiple SPPs with low order. In this study, we numerically calculate the transmitted light field of cascaded multiple SPPs according to the Huygens–Fresnel diffraction integral, and perform the experimental verifications. Based on cascading 6 SPPs (3 SPPs with TCs of 2, and 3 SPPs with TCs 4, respectively), an VB with TCs as high as 18 is generated. Furthermore, The TCs of the generated VB are detected by coaxial and off-axis interfering with fundamental Gaussian beam or its conjugate beam, respectively. The generated fork and spiral patterns allow us to distinguish the value and sign of TCs carried by the VB. The experimental results coincide well with the theoretical simulations. The fork pattern shows better resolution than the spiral one, and the petal pattern with small spiral allows us to distinguish large TCs with a higher resolution.
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