Gradient Model Research Articles

A Hybrid Light Gradient Boosting Approach with Deep Boltzmann Machine for Intrusion Detection System

The need for network attack analysis and the number of cyber threats and attacks are increasing. Due to the scalability and adaptability of its internet-based computing resources, cloud computing is gaining popularity among businesses worldwide. Scientists are increasingly interested in cloud data security and face the difficulty of protecting hosts, enterprises, and data against more advanced digital threats. Over the past few decades, researchers have experimented with the Intrusion Detection (ID) paradigm, leading to various methodologies. However, critical to analyze the abnormalities in the intrusion detection framework. This research aims to classify the attacks or abnormalities in the network included in the NSL-KDD dataset using a Hybrid Light Gradient Boosting approach with Deep Boltzmann Machine. A Deep Boltzmann Machine Classifier and an ensemble model of the Light Gradient Boosting technique were used to create this model. Gradient boosting techniques improve the performance of DL classifiers by minimizing the number of errors discovered during network intrusion detection. This work evaluates and contrasts the proposed classifier with recognized classification strategies. The proposed model surpasses previous Recall, F-Measure, Precision, and Accuracy techniques.

Efficient and Selective Construction of 412 Metalla‐links Using Weak C−H⋅⋅⋅Halogen Interactions

AbstractThrough a coordination‐driven self‐assembly method, four metalla‐links and one tetranuclear monocycle were constructed with high selectivity and yield by adjusting the substituent species of the building blocks, as evidenced using X‐ray crystallographic analysis, electrospray ionization‐time‐of‐flight/mass spectrometry (ESI‐TOF/MS), elemental analysis and detailed solution‐state nuclear magnetic resonance (NMR) spectroscopy. Based on X‐ray crystallographic analysis and independent gradient model analysis, a significant factor leading to the formation of metalla‐links was the introduction of F, Cl, Br and I atoms, which generated additional weak C−H⋅⋅⋅X (X=F, Cl, Br and I) interactions. Furthermore, the dynamic conversion of metalla‐links to monocyclic rings in methanol solution was systematically investigated using quantitative 1H NMR techniques.

Efficient and Selective Construction of 41 2 Metalla-links Using Weak C-H⋅⋅⋅Halogen Interactions.

Through a coordination-driven self-assembly method, four metalla-links and one tetranuclear monocycle were constructed with high selectivity and yield by adjusting the substituent species of the building blocks, as evidenced using X-ray crystallographic analysis, electrospray ionization-time-of-flight/mass spectrometry (ESI-TOF/MS), elemental analysis and detailed solution-state nuclear magnetic resonance (NMR) spectroscopy. Based on X-ray crystallographic analysis and independent gradient model analysis, a significant factor leading to the formation of metalla-links was the introduction of F, Cl, Br and I atoms, which generated additional weak C-H⋅⋅⋅X (X=F, Cl, Br and I) interactions. Furthermore, the dynamic conversion of metalla-links to monocyclic rings in methanol solution was systematically investigated using quantitative 1H NMR techniques.

Multilayer heterostructure inhomogeneous model for the functionally graded spherical shell with rotation effect for arbitrarily varying material properties

With the development of functionally graded materials (FGMs) composite technology, structural safety analysis related to FGMs has been widely concerned. An innovative multilayer heterostructure power-law inhomogeneous (MHPI) model is taken to solve the rotating FGMs hollow spherical shell with arbitrarily varying material properties (elastic modulus and density) along the radial direction. The basic idea of MHPI model is that the rotating FGMs spherical shell is divided into multiple sublayers, and two power functions approximate the elastic modulus and density of each sublayer respectively. For each single sublayer, the analytical solutions include two undetermined constants, which can be obtained from the boundary and continuity conditions. Many numerical examples of the rotating FGMs spherical shell are discussed, involving seven property profiles gradient laws assumptions, three boundary conditions, and nine volume fraction gradient models. Finally, this study further discusses the rotating FGMs spherical shell optimization design. The greatest advantage of this study is that the elastic response of the rotating FGMs spherical shell under various gradient assumptions is completely discussed. The numerical results show that the MHPI model can solve the problem of circumferential stress oscillation well and have good convergence and high accuracy. For many numerical examples, the error of the MHPI model results is about 5‰ when sublayer number reaches 15.

Ionic liquid-assisted extractive distillation for separating of ethyl acetate/isopropanol from chemical wastewater: Molecular insights and process intensification

The effective separation of ethyl acetate (EAC)/isopropanol(IPA)/water azeotrope from industrial wastewater significantly reduces environmental risks and recycling resources. An azeotrope separation technique was proposed, combining ionic liquid mixed entrainer and dividing wall column extractive distillation (DWC-ED). The selectivity and solubility of 225 ionic liquids were calculated based on the COSMO-RS model. The molecular polarity of EAC, IPA, H2O, dimethyl sulfoxide (DMSO), and [EMIM][AC] was studied, and 1-ethyl-3-methylimidazolium acetate ([EMIM][AC]) was determined as the best solvent. In addition, the interaction mechanism between [EMIM][AC] (or DMSO) and EAC/IPA/H2O was studied using the quantum chemistry (QC) theory. Independent gradient model (IGM), interaction energy, and atoms in molecules (AIM) analysis showed that hydrogen bonds and vdW forces were formed between [AC]− anion and H2O/IPA/EAC, and the interaction energy was gradually weakened, which significantly improved the performance of extractive distillation process. The results showed that the total annual cost (TAC) and energy consumption of IL-based mixed solvent extractive distillation were reduced by 36.04 % and 37.72 %, respectively, compared to the single DMSO extractive distillation process. The TAC and energy consumption of the DWC-ED process were 44.61 % and 51.43 % lower than the benchmark processes.

Halogen Bond via an Electrophilic π-Hole on Halogen in Molecules: Does It Exist?

This study reveals a new non-covalent interaction called a π-hole halogen bond, which is directional and potentially non-linear compared to its sister analog (σ-hole halogen bond). A π-hole is shown here to be observed on the surface of halogen in halogenated molecules, which can be tempered to display the aptness to form a π-hole halogen bond with a series of electron density-rich sites (Lewis bases) hosted individually by 32 other partner molecules. The [MP2/aug-cc-pVTZ] level characteristics of the π-hole halogen bonds in 33 binary complexes obtained from the charge density approaches (quantum theory of intramolecular atoms, molecular electrostatic surface potential, independent gradient model (IGM-δginter)), intermolecular geometries and energies, and second-order hyperconjugative charge transfer analyses are discussed, which are similar to other non-covalent interactions. That a π-hole can be observed on halogen in halogenated molecules is substantiated by experimentally reported crystals documented in the Cambridge Crystal Structure Database. The importance of the π-hole halogen bond in the design and growth of chemical systems in synthetic chemistry, crystallography, and crystal engineering is yet to be fully explicated.

Understanding the interactions between anticancer active molecules Cp2TiCl2 and Cp2VCl2 and E@Al12 (E = C, Si) clusters using density functional theory calculations

This work investigated the interaction between E@Al12 (E = C, Si) clusters and titanocene dichloride (TDC) and vanadocene dichloride (VDC) anticancer drugs using BP86. Corrected interaction energy values of the complexes were computed. Interaction effect on the frontier orbital energy values of the pure nano-cluster and drugs were illustrated. Also, electrophilicity-based charge transfer (ECT) was indicated charge flow from anticancer drug to nano-cluster. Cl⋅⋅⋅Al weak non-covalent interactions in the studied systems were explored with Independent gradient model analysis based on Hirshfeld partition of molecular density (IGMH) and Non-covalent interaction (NCI). QTAIM analysis was considered to exploring of bond critical point of Al…Cl.

Salt tolerance and survival of the freshwater bioinvasive gastropod Melanoides tuberculata (Thiariidae): when different methodologies tell us different stories

ABSTRACT The study of the ecophysiology of invasive species is one of the main steps in understanding the dynamics of territorial expansion of these species and establishing prevention, control, and combat measures and protocols. For freshwater molluscs, one of the main limiting factors is salinity. Laboratory tests closer to reality are needed to make more efficient models. Melanoides tuberculata is an invasive freshwater snail monitored worldwide, and it also has implications for human health. Recent studies supported that its rapid expansion has been enabled through its adaptation to both estuarine conditions and saline waters. The present study aims to determine the real tolerance range of M. tuberculata through a stepwise acclimation test as a more realistic model of a transitional gradient from a lentic to an estuarine environment and so determine the real potential for salinity adaptation. It also aims to check differences in the tolerance responses between age groups and life history, using two distinct populations subject to distinct ambient conditions. The stepwise acclimation test was effective in proving that M. tuberculata may be highly adaptable to salinity variation, contrasting with all previous tests. Thus, the results support the hypothesis of dispersion via estuaries by salinity-tolerant M. tuberculata juveniles.

Molecular Insights into the Dual Promotion-Inhibition Effects of NaCl at Various Concentrations on the CO2 Hydrate Growth: A Molecular Simulation Study.

Hydrate-based CO2 storage in the ocean is considered a potential method for mitigating the greenhouse effect. Numerous studies demonstrated that NaCl exhibited the dual effects of promotion and inhibition in the nucleation and growth processes of CO2 hydrate, whose mechanisms remain unclear. In this study, the effects of NaCl at various concentrations on the CO2 hydrate growth and crystal are investigated. The independent gradient model based on Hirshfeld partition, electrostatic potential, and binding energy is conducted to study the interaction between ions and water molecules. The motion trajectories of ions are observed at the molecular level to reflect the impact of ion motion on hydrate growth. The results show that the influence of NaCl on hydrate growth depends on a delicate balance of dual promotion-inhibition effects. NaCl can combine more water molecules and provide a transport channel of CO2 to promote hydrate growth at low concentrations. Meanwhile, the promoting effects shift toward inhibition with increasing NaCl concentrations. In a word, this paper proposes a novel mechanism for the dual promotion-inhibition effects of NaCl on hydrate growth, which is significant for further research on hydrate-based CO2 storage in the ocean.

Mechanism analysis and energy-saving intensified exploration of green mixed solvents extractive distillation to separate ether-containing azeotropes

2-Methoxyethanol is an important solvent with wide application prospects. Recovering 2-Methoxyethanol from wastewater has significant environmental and economic benefits. In this work, quantum chemistry methods are used to calculate the surface electrostatic potential, mutual penetration analysis, and reduced density gradient-independent gradient model of solvents and azeotrope. From the perspective of the mechanism of action, suitable extractants are selected. With the minimum total annual cost as the goal, the splendid process parameters and the excellent ratio of mixed solvents (30 % 1-ethyl-3-methylimidazole acetate + 70 % N, N-dimethyl acetamide) are acquired. Moreover, two reinforcing processes for energy saving and consumption reduction are also researched. All processes are appraised from three aspects: economy, environment and exergy. The results show that the total annual cost and gas emission of mixed solvent extraction distillation are reduced by 26.79 % and 35.45 %, respectively, compared with the process with NMP as an entrainer. Compared with the process with [EMIM][AC] as an entrainer, the total annual cost and gas emissions are reduced by 44.99 % and 25.04 %, respectively. Relative to mixed solvent, the total annual cost and gas emissions of the heat pump combined with mixed solvent extractive distillation technology decreased by 6.77 % and 21.78 % respectively, while that of the heat integration process decreased via 9.93 % and 12.30 % respectively. From the point of view of environmental sustainability, the process effect combined with the heat pump is better, and from the point of view of economic benefits, the heat integration process has better performance. This study reveals the intrinsic relationship between the structure of mixed solvents and explores the intensification of the process, which provides a theoretical basis for the industrial separation of 2-Methoxyethanol/water azeotrope.

Research on the application of Ti-MoTe2 in cable condition assessment as gas sensor: A First-principles study

XLPE cables inevitably have defects that can cause them to deteriorate. The operational condition of cables can be assessed by detecting gases from overheating and discharge. Ti doped MoTe2 has excellent adsorption properties for gas molecules which leads to the application potential in gas sensors. In this paper, the doping process of Ti on MoTe2 is simulated, and the doping properties of Ti are analyzed. The adsorption properties of Ti-MoTe2 on four pyrolytic components (CO, CH4, C2H4 and C2H6) are investigated based on adsorption configuration, electron localization function (ELF), independent gradient model based on Hirshfeld partition (IGMH), and density of states (DOS) analyses. Finally, the potential application of Ti-MoTe2 as a sensing material is comprehensively evaluated in conjunction with the sensing properties. The results showed that the adsorption energy and transfer charge of Ti-MoTe2 to CO are −0.891 eV and −0.239 e, respectively The ELF between CO and Ti-MoTe2 is as high as 0.6 with a significant electronic localization. The IGMH results also show a significant chemical bonding force between CO and Ti. Meanwhile, the sensitivity and recovery time of Ti-MoTe2 for CO are ideal, and it can be used as a gas sensor for CO, which in turn can be used for cable condition assessment. However, the adsorption properties of Ti-MoTe2 for CH4, C2H4 and C2H6 are poor, which makes it unsuitable for the detection of these gases. The research results in this paper can provide theoretical basis and data support for the application of Ti-MoTe2 sensors.

Shedding light on the strength, nature, and cooperativity/anti-cooperativity between intermolecular H…N hydrogen and Cl…C halogen bonds in the competitive binary and ternary complexes

In equimolar mixture of monomers N≡C-Cl (M−1) and C=N-H (M−2), formation of N…H hydrogen-bonded complex HB-Dim and C…Cl halogen-bonded complex XB-Dim compete with each other. Values of counterpoise-corrected interaction energy indicate that HB-Dim is absolute winner in such a competition. Existence of N…H HB- and C…Cl XB-interactions is characterized through geometrical parameters analysis, Quantum theory of atoms-in-molecules descriptors, and Independent gradient model based on Hirshfeld partition of molecular density. Interaction energy decomposition reveals that electrostatic with orbital interactions and, electrostatic with dispersion interactions are main driving forces for the formation of, respectively, HB- and XB-Dim. Moreover, substantially stronger electrostatic and orbital interactions characterized with Molecular electrostatic potential and Extended Transition State-Natural Orbitals for Chemical Valence analyses explain why formation of HB-Dim is quite preferred over that of XB-Dim. Two N…H HB- and C…Cl XB-interactions, present at the same time, make each other slightly strength in ternary complex Trim.

A Novel Threshold Pressure Gradient Model and Its Influence on Production Simulation for Shale Oil Reservoirs

A Novel Threshold Pressure Gradient Model and Its Influence on Production Simulation for Shale Oil Reservoirs

Isotope impact on Alfvén eigenmodes and fast ion transport in DIII-D

Measurements of beam driven Alfvén Eigenmode (AE) activity in matched deuterium (D) and hydrogen (H) DIII-D plasmas show a dramatic difference in unstable mode activity and fast ion transport for a given injected beam power. The dependence of the unstable AE spectrum in reversed magnetic shear plasmas on beam and thermal species is investigated in the current ramp by varying beam power in a sequence of discharges for fixed thermal and beam species at fixed density. In general, a spectrum of Reversed Shear Alfvén Eigenmodes (RSAEs) and Toroidal Alfvén Eigenmodes (TAEs) are driven unstable with sub-Alfvénic D beam injection while primarily only RSAEs are driven unstable for the H beam cases investigated. Further, for a given beam power, the driven AE amplitude is always reduced with H beams relative to D and for H thermal plasma relative to pure D or mixed D/H plasmas. Estimates of the fast ion stored energy combined with modeling using the hybrid kinetic-MHD code MEGA indicate that the dominant mechanism contributing to the difference between H and D beam drive is the faster classical slowing down of H beam ions relative to D and the resultant lower beam ion pressure. Calculations of the AE induced stored energy deficits using the reduced critical gradient model TGLFEP show quantitative agreement with the observed dependencies on injected power, isotope and minimum safety factor.

Variability and loss of uniqueness of numerical solutions in FEM×DEM modeling with second gradient enhancement

AbstractIn the last decade, a new multi‐scale FEM×DEM approach has been developed using Finite Element Method (FEM) coupled with Discrete Element Method (DEM) as a constitutive law to account for the specificities of the mechanical behavior of granular materials. In FEM×DEM model, a DEM calculation is performed on a particle assembly (volume element—VE) at each Gauss point. Recent publications have demonstrated that FEM×DEM approach naturally captures the discrete and anisotropic nature of granular materials. Despite its advantages, FEM×DEM with classical FEM, suffers from mesh dependency, especially when material enters softening phase and exhibits strain localization. To overcome this limitation, FEM×DEM model has been enriched by incorporating a local second gradient model. Nevertheless, the existence of multiple possible solutions is observed. In this paper, we study the variability and loss of uniqueness of numerical solutions to a boundary value problem. Different VEs with equivalent mechanical properties are generated and used to model the pressuremeter tests by means of FEM×DEM. The modeling results show a great variability of the numerical results, both in shape of borehole and in different modes of shear bands. For the same VE, the loss of uniqueness of numerical solutions is evidenced by a slight modification of loading history at the level of the internal pressure applied to the borehole. Finally, we show that when a certain heterogeneity is introduced by using different VEs within the same BVP, even if the uniqueness of the solution is not guaranteed, the set of possible solutions seems more restrained.

Subsidence-induced early doming at a large ignimbrite caldera

Uplift at many well-documented resurgent calderas started only after completion of the associated ignimbrite eruption, but arching of the large Bachelor caldera in the Southern Rocky Mountain volcanic field, Colorado (USA), began during the eruption. A well-defined arched or domical structure, initiated within thickly accumulating ignimbrite as the caldera subsided, is documented by growth of keystone faults as the caldera filled, rheomorphism and local diapiric mobilization of early-erupted tuff, decreased dips in upper welding zones, and wedging of a late-erupted dacitic phase against flanks of the growing dome. Early subsidence-induced doming may have been triggered by preferential magma draw-down along ring-fault vents, relatively impermeable vesiculation and differential magma buoyancy centrally within the caldera, peripheral loading at caldera margins by landslides and talus from caldera walls, or some combination of factors. Early inception of caldera doming has implications for models of magma withdrawal and residual compositional gradients in non-erupted magma.

Vibrational analysis of graphyne-based nanoplates using a hybrid nonlocal strain gradient-atomistic simulation model

By employing a hybrid atomistic-continuum model, we can combine the advantages of atomic and continuum models. In this approach, resonance frequencies are matched to those obtained from the continuum model using the size effect and Young’s modulus as fit parameters. Our proposed method examines how radius affects the elastic modulus, size effect parameters, and resonance frequency values of the graphyne family, taking into account both macro and nano-scale models. The non-local strain gradient model has been calibrated to achieve optimal error. In contrast, the error is highest when the non-local strain gradient effect is not considered in the continuum mechanics model.

Development of a new rotational irrigation model in an arid basin based on ecological zoning and sluice regulation

Precise and efficient allocation of existing water resources is of great significance to protect and restore desert riparian forests in inland river basins. However, the lack of detailed ecological zoning in most basins hinders the optimization of the current ecological sluice regulation scheme, leading to low effectiveness in vegetation restoration and water resources management. To address this problem, we proposed for the first time an ecological zoning method that integrates the vegetation gradient model and control of ecological sluices. Specifically, the mainstream of Tarim River basin (China) was classified into three types of ecological functional zones, i.e., key protection, key restoration, and ecologically sensitive zones, based on the kernel NDVI (kNDVI) gradient detection framework. On this basis, the basin was divided into 27 sluice group control areas determined by the control range of ecological sluices and the study area was further divided into five grades zones of ecological rotation irrigation. Based on the results of ecological zoning and the priorities of rotational irrigation, this study proposes a new rotational irrigation model in the basin to further promote vegetation recovery. The results showed that guarantee rate of ecological water supply to vegetation protection and restoration increased from 82.3% to 101.7% before and after rotational irrigation, respectively, indicating the effectiveness of this new method. The results of this study have a practical value and may significantly contribute to the optimal allocation and management of water resources in global arid basins.

Enantioselective domino alkyl arylation of vinyl phosphonates by combining photoredox and nickel catalysis

A nickel/photoredox mediated asymmetric domino alkyl arylation of vinyl phosphonates to generate a diverse array of enantioenriched α-aryl phosphonates is disclosed. This asymmetric three-component difunctionalization couples aryl halides and alkyl bromides with vinyl phosphonates, exhibiting excellent chemo- and regioselectivity under mild reaction conditions. The method avoids the need for pre-formed organometallics and phosphorus halides. Mechanistic and DFT studies suggest that photoexcited [4CzIPN]* oxidizes diethyl 1,4-dihydro-2,6-dimethyl-3,5-pyridinedicarboxylate (HEH) to generate the [4CzIPN]•–, which then reduces the alkyl bromide to form alkyl radicals that undergo Giese addition to the vinyl phosphonate. At the same time, Ni0 oxidatively adds the aryl bromide followed by enantiodetermining oxidative radical trapping of the phosphonate-based radical by the tetrahedral NiII center followed by reductive elimination. Independent gradient model based on Hirshfeld partition (IGMH) analysis suggests that the orientation of the phosphonate group (P=O…π interaction) is expected to play an essential role in controlling the enantioselectivity.

Self-assembly of metal-polyphenolic network on biomass for enhanced organic contaminant capturing from water with a high cost-to-benefit ratio

Nanomaterials present a vast potential as functional materials in environmental engineering. However, there are challenges with nanocomplex for recyclability, reliable/stable, and scale-up industrial integration. Here, a versatile, low-cost, stable and recycled easily metal-polyphenolic-based material carried by wood powder (bioCar-MPNs) adsorption platform was nano-engineered by a simple, fast self-assembly strategy, in which wood powder is an excellent substrate serving as a scaffold and stabilizer to prevent the nanocomplex from aggregating and is easier to recycle. Life cycle analysis highlights a green preparation process and environmental sustainability for bioCar-MPNs. The metal-polyphenolic nanocomplex coated on the wood surface in bioCar-MPNs presents a remarkable surface adsorption property (1829.4 mg/g) at a low cost (2.4 US dollars per 1000 g bioCar-MPNs) for organic dye. Quartz crystal microbalance analysis (QCM) demonstrates an existing strong affinity between polyphenols and organic dyes. Furthermore, Independent Gradient Model (IGM) and Hirshfeld surface analysis reveal the presence of the electrostatic interactions, π-π interactions, and hydrogen bonding. Meanwhile, adsorption efficiency of bioCar-MPNs maintains over 95% in the presence of co-existing ions (Na+, 0.5 M). Importantly, the reasonable utilization of biomass for water treatment can contribute to achieving the high-value and resource utilization of biomass materials.