Combining machine learning algorithms with traditional methods for resolving the atomic-scale dynamic structure of monolayer MoS_(2) in high-resolution transmission electron microscopy

High-resolution transmission electron microscopy(HRTEM)promises rapid atomic-scale dynamic structure imaging.Yet,the precision limitations of aberration parameters and the challenge of eliminating aberrations in Cs-corrected transmission electron microscopy constrain resolution.A machine learning algorithm is developed to determine the aberration parameters with higher precision from small,lattice-periodic crystal images.The proposed algorithm is then validated with simulated HRTEM images of graphene and applied to the experimental images of a molybdenum disulfide(MoS_(2))monolayer with 25 variables(14 aberrations)resolved in wide ranges.Using these measured parameters,the phases of the exit-wave functions are reconstructed for each image in a focal series of MoS_(2)monolayers.The images were acquired due to the unexpected movement of the specimen holder.Four-dimensional data extraction reveals time-varying atomic structures and ripple.In particular,the atomic evolution of the sulfur-vacancy point and line defects,as well as the edge structure near the amorphous,is visualized as the resolution has been improved from about 1.75?to 0.9 A.This method can help salvage important transmission electron microscope images and is beneficial for the images obtained from electron microscopes with average stability.

Opportunities to Improve the Quality of Environmental Reports and the Effectiveness of Environmental Impact Assessment: A Case of Electric Power Transmission Systems in Brazil

A good quality Environmental Impact Statement (EIS) is key for the effectiveness of Environmental Impact Assessment (EIA) processes and consequently to the acceptability of projects subject to EIA. The international literature has contributed to the understanding of the essential aspects to be verified regarding the quality of EIS, offering a wide spectrum of good practice examples related to the content of the studies. Even so, there is a need for empirical studies that allow the identification of specific aspects related to the context of application of the EIS, which could lead to the identification of opportunities to improve both the quality of the reports and also the effectiveness of EIA. Therefore, the present paper is focused on the quality review of a number of EIS submitted to the Brazilian Federal Environmental Agency (Ibama) to instruct the assessment of electric power transmission systems. Based on the application of the EIS quality review package as proposed by Lee and Colley (1992), the outcomes reveal opportunities for improving the scope of EIA, analysis of alternatives, prediction of magnitude and the assessment of impact significance. Finally, the development and/or adaptation of a similar tool for the systematic review of the quality of EIA reports is recommended.

Identification of the Asymmetric Transmission Error and Gear Mesh Dynamic Parameters using Full-Spectrum Responses in a Geared-Rotor System

A dominant source of vibration in geared-rotor systems is the gear mesh fault parameters.They include the asymmetric transmission error(TE),phases of TE,the gear mesh stiffness,the gear mesh damping,and the gear runouts.The present work deals with the experimental identification of the aforementioned parameters.A mathematical model of a geared-rotor system has been developed using Lagrangian dynamics.Equations of motion are transformed into the frequency domain using the full-spectrum response analysis.These transformed equations are used to develop an identification algorithm(IA)based on least-squares fit to estimate the TE and gear mesh dynamic parameters.The system IA is initially verified using numerical simulations.The robustness of the algorithm is checked by introducing white Gaussian noise in the simulated responses.A geared-rotor experimental rig was developed and used to measure responses at gear locations in two orthogonal directions.Measured responses are transformed in the frequency domain using the full-spectrum analysis and used in the present novel IA to identify the gear parameters.The identified parameters are validated by comparing the numerically generated full-spectrum response using experimentally estimated parameters and that from the experimental rig.

Dynamic Characteristics of Transmission System for the Internal Grinder

The dynamics model of the transmission system of the internal grinder is established on the bases of Riccati transfer matrix. The dynamic characteristics of the internal grinder are obtained by analyzing the relationship between dynamic modal flexibility and modal flexibility, which is used to find out the dangerous model of the transmission system and its weak areas. Then design parameters of weak areas are modified, the new one from the old structure is put forward, and the dynamic characteristics of new ...

Fault Diagnosis of Vehicle Transmission System Based on Rough Set Theory

Rough set theory is used to treat the data of vehicle transmission system faults. The minimum fault feature vector can be obtained by calculating the importance and dependency of each attribute. Real time diagnosis, as a result, can be actualized. Ultimate decision making can be done by analyzing the consistency of decision information. The result shows that rough set theory is useful and possesses its unique merits in this field.

STUDY OF ROLLING FORCE DISTRIBUTION ALONG THE ROLLING OF PAIR CROSS MILL

The theory of three-dimensional deformation is used.Based on rigid plastic assumption, the theory of stick friction and the sheet crown curve at the entry and the exit are used. The mathematical analytical formula of the rolling force in lateral distribution is deriven.

Targeting harmful effects of non-excitatory amino acids as an alternative therapeutic strategy to reduce ischemic damage

The involvement of the excitatory amino acids glutamate and aspartate in ce rebral ischemia and excitotoxicity is well-documented.Nevertheless,the role of non-excitatory amino acids in brain damage following a stroke or brain trauma remains largely understudied.The release of amino acids by necrotic cells in the ischemic core may contribute to the expansion of the penumbra.Our findings indicated that the reversible loss of field excitato ry postsynaptic potentials caused by transient hypoxia became irreversible when exposed to a mixture of just four non-excitatory amino acids(L-alanine,glycine,L-glutamine,and L-serine)at their plasma concentrations.These amino acids induce swelling in the somas of neurons and astrocytes during hypoxia,along with permanent dendritic damage mediated by N-methyl-D-aspartate receptors.Blocking N-methyl-D-aspartate receptors prevented neuronal damage in the presence of these amino acids during hypoxia.It is likely that astroglial swelling caused by the accumulation of these amino acids via the alanine-serine-cysteine transporter 2 exchanger and system N transporters activates volume-regulated anion channels,leading to the release of excitotoxins and subsequent neuronal damage through N-methyl-D-aspartate receptor activation.Thus,previously unrecognized mechanisms involving non-excitatory amino acids may contribute to the progression and expansion of brain injury in neurological emergencies such as stroke and traumatic brain injury.Understanding these pathways co uld highlight new therapeutic targets to mitigate brain injury.

Microstructure evolution and strengthening mechanism of high -performance powder metallurgy TA15 titanium alloy by hot rolling

Hot deformation of sintered billets by powder metallurgy(PM)is an effective preparation technique for titanium alloys,which is more significant for high-alloying alloys.In this study,Ti–6.5Al–2Zr–Mo–V(TA15)titanium alloy plates were prepared by cold press-ing sintering combined with high-temperature hot rolling.The microstructure and mechanical properties under different process paramet-ers were investigated.Optical microscope,electron backscatter diffraction,and others were applied to characterize the microstructure evolution and mechanical properties strengthening mechanism.The results showed that the chemical compositions were uniformly dif-fused without segregation during sintering,and the closing of the matrix craters was accelerated by increasing the sintering temperature.The block was hot rolled at 1200℃ with an 80%reduction under only two passes without annealing.The strength and elongation of the plate at 20–25℃ after solution and aging were 1247 MPa and 14.0%,respectively,which were increased by 24.5%and 40.0%,respect-ively,compared with the as-sintered alloy at 1300℃.The microstructure was significantly refined by continuous dynamic recrystalliza-tion,which was completed by the rotation and dislocation absorption of the substructure surrounded by low-angle grain boundaries.After hot rolling combined with heat treatment,the strength and plasticity of PM-TA15 were significantly improved,which resulted from the dense,uniform,and fine recrystallization structure and the synergistic effect of multiple slip systems.

Influence of symmetric and asymmetric rolling on texture evolution of work-hardened AA 5xxx aluminium alloy

The textures and microstructures of hot-and cold-rolled sheets of an AA 5454 aluminium alloy were studied,with special attention paid to comparing the texture development for the symmetric and asymmetric cold rolling.Scanning electron microscopy with electron-backscatter diffraction was used to monitor the development of the microstructure in the differently deformed and additionally annealed samples.Details of the formations and transformations of individual texture components occurring during the rolling processes were observed and discussed.The average grain sizes,textures and mechanical properties were correlated and explained for the symmetric and asymmetric cold-rolled samples.The asymmetric rolling is beneficial in terms of deep drawability because it reduces the planar anisotropy of the annealed material due to the decrease of the Cube,Goss,rotated-Cube and η-fibre texture components and at the same time strengthens X1-and X2-fibre texture components which are shear texture components and improve deep drawability.During the asymmetric cold rolling,the temperature increases due to friction,triggering recrystallisation processes and leading to larger grains.It is also confirmed that asymmetric cold rolling uses less rolling force and consequently less energy to produce a final material with better formability,particularly earing.

Inhibitory gamma-aminobutyric acidergic neurons in the anterior cingulate cortex participate in the comorbidity of pain and emotion

Pain is often comorbid with emotional disorders such as anxiety and depression.Hyperexcitability of the anterior cingulate cortex has been implicated in pain and pain-related negative emotions that arise from impairments in inhibitory gamma-aminobutyric acid neurotransmission.This review primarily aims to outline the main circuitry(including the input and output connectivity)of the anterior cingulate cortex and classification and functions of different gamma-aminobutyric acidergic neurons;it also describes the neurotransmitters/neuromodulators affecting these neurons,their intercommunication with other neurons,and their importance in mental comorbidities associated with chronic pain disorders.Improving understanding on their role in pain-related mental comorbidities may facilitate the development of more effective treatments for these conditions.However,the mechanisms that regulate gamma-aminobutyric acidergic systems remain elusive.It is also unclear as to whether the mechanisms are presynaptic or postsynaptic.Further exploration of the complexities of this system may reveal new pathways for research and drug development.

Short-Term Rolling Prediction of Tropical Cyclone Intensity Based on Multi-Task Learning with Fusion of Deviation-Angle Variance and Satellite Imagery

Tropical cyclones(TCs)are one of the most serious types of natural disasters,and accurate TC activity predictions are key to disaster prevention and mitigation.Recently,TC track predictions have made significant progress,but the ability to predict their intensity is obviously lagging behind.At present,research on TC intensity prediction takes atmospheric reanalysis data as the research object and mines the relationship between TC-related environmental factors and intensity through deep learning.However,reanalysis data are non-real-time in nature,which does not meet the requirements for operational forecasting applications.Therefore,a TC intensity prediction model named TC-Rolling is proposed,which can simultaneously extract the degree of symmetry for strong TC convective cloud and convection intensity,and fuse the deviation-angle variance with satellite images to construct the correlation between TC convection structure and intensity.For TCs'complex dynamic processes,a convolutional neural network(CNN)is used to learn their temporal and spatial features.For real-time intensity estimation,multi-task learning acts as an implicit time-series enhancement.The model is designed with a rolling strategy that aims to moderate the long-term dependent decay problem and improve accuracy for short-term intensity predictions.Since multiple tasks are correlated,the loss function of 12 h and 24 h are corrected.After testing on a sample of TCs in the Northwest Pacific,with a 4.48 kt root-mean-square error(RMSE)of 6 h intensity prediction,5.78 kt for 12 h,and 13.94 kt for 24 h,TC records from official agencies are used to assess the validity of TC-Rolling.

Tailoring the texture and mechanical properties of 3%Y_(2)O_(3)p/ZGK200 composites fabricated by unidirectional and cross rolling followed by annealing

3%Y_(2)O_(3)p/ZGK200 composites were subjected to unidirectional rolling(UR)and cross rolling(CR)at 400℃and 350℃followed by annealing at 300℃for 1 h.The microstructure,texture and mechanical properties of rolled and annealed composites were systematically studied.The rolled composites exhibited a heterogeneous microstructure,consisting of deformed grains elongated along rolling direction(RD)and Y_(2)O_(3)particles bands distributed along RD.After annealing,static recrystallization(SRX)occurred and most deformed grains transformed into equiaxed grains.A non-basal texture with two strong T-texture components was obtained after UR while a non-basal elliptical/circle texture with circle multi-peaks was obtained after CR,indicating that rolling path had great influences on texture of the composites.After annealing process,R-texture component disappeared or weakened,as results,a non-basal texture with double peaks tilting from normal direction(ND)to transverse direction(TD)and a more random non-basal texture with circle multi-peaks were obtained for UR and CR composites,respectively.The yield strength of rolled composites after UR showed obvious anisotropy along RD and TD while a low anisotropic yield strength was obtained after CR.Some Y_(2)O_(3)particles broke during rolling.The fracture of the composites was attributed to the existence of Y_(2)O_(3)clusters and interfacial debonding between particles and matrix during tension,as a result,the ductility was not as superior as matrix alloy.

Mother-to-Child Transmission of Human Papillomavirus in Burkina Faso

Introduction: Human papillomavirus (HPV) infection is the most widespread sexually transmitted infection in the world. Today, there is growing evidence that HPV can be transmitted early in life, and one potential route is mother-to-child transmission. Data on this route of HPV transmission are scarce in Africa and particularly in Burkina Faso, where no data on the subject are yet available. The aim of our study was to estimate the rate of mother-to-child transmission of HPV infection and to identify circulating genotypes. Methodology: Cervico-uterine samples were collected from 100 full-term pregnant women and, buccal samples were obtained from their newborns at Hopital Saint Camille de Ouagadougou (HOSCO) by the specialist physician. HPV DNA amplification and genotyping were performed by PCR followed by hybridization using the HPV Direct Flow Chips kit, detecting 36 genotypes including 18 high-risk and 18 low-risk. Results: The prevalence of HPV in newborns was 8% (8/100). Six (6) HPV-positive neonates had HPV-positive mothers, while 2 HPV-positive neonates had HPV-negative mothers. The vertical transmission rate was 26.09% (6/23). Mother-newborn genotypes were concordant. However, the genotype profile of the newborns was more restricted than that of the mothers. Conclusion: HPV DNA was found in 8% of newborns in our study. The genotype profile of the mother-newborn pair was concordant. Asymptomatic HPV infection in a pregnant woman could constitute a risk factor for vertical transmission.

Effects of cross-Kerr coupling on transmission spectrum of double-cavity optomechanical system

We theoretically study the transmission spectrum of the cavity field in a double-cavity optomechanical system with cross-Kerr(CK) effect. The system consists of two tunneling coupling optomechanical cavities with a mechanical resonator as a coupling interface. By doping CK medium into the mechanical resonator, CK couplings between the cavity fields and the mechanical resonator are introduced. We investigate the effects of CK coupling strength on the transmission spectrum of the cavity field, including the transmission rate, nonreciprocity and four-wave mixing(FWM). We find that the transmission spectrum of the probe field can show two obvious transparent windows, which can be widened by increasing the CK coupling strength. For the transmission between the two cavity fields, the perfect nonreciprocity and reciprocity are present and modulated by CK coupling and phase difference between two effective optomechanical couplings. In addition, the effects of the optomechanical and CK couplings on FWM show that the single peak of FWM is split into three symmetrical peaks due to the introduction of the CK effect.

Revealing the microstructures of metal halide perovskite thin films via advancedtransmission electron microscopy

Metal halide perovskites (MHPs) are excellent semiconductors that have led to breakthroughs in applications in thinfilmsolar cells, detectors, and light-emitting diodes due to their remarkable optoelectronic properties and defect tolerance.However, the performance and stability of MHP-based devices are significantly influenced by their microstructures includingthe formation of defects, composition fluctuations, structural inhomogeneity, etc. Transmission electron microscopy(TEM) is a powerful tool for direct observation of microstructure at the atomic-scale resolution and has been used to correlatethe microstructure and performance of MHP-based devices. In this review, we highlight the application of TEMtechniques in revealing the microstructures of MHP thin films at the atomic scale. The results provide critical understandingof the performance of MHP devices and guide the design of strategies for improving the performance and stability ofMHP devices.

Unveiling the rolling texture variations ofα-Mg phases in a dual-phase Mg-Li alloy

LZ91 Mg-Li alloy plates with three types of initial texture were rolled by 70%reduction at both room temperature and 200℃to explore the rolling texture formation ofα-Mg phase.The results showed that the rolling texture is largely affected by the initial texture.All the samples exhibited two main texture components as RD-split double peaks texture and TD-split double peaks texture after large strain rolling.The intensity of the two texture components was strongly influenced by the initial orientation and rolling temperature.Extension twinning altered the large-split non-basal orientation to a near basal one at low rolling strain.The basal orientation induced by twinning is unstable,which finally transmitted to the RD-split texture.The strong TD-split texture formed due to slip-induced orientation transition from its initial orientation.The competition between prismatic and basal slip determined the intensity and tilt angle of the TD-split texture.By increasing the rolling temperature,the TD-split texture component was enhanced in all three samples.Limitation of extension twinning behavior and the promotion of prismatic slip at elevated temperature are the main reasons for the difference in hot and cold rolling texture.

Design,preparation,microstructure and mechanical property of the lightweight radiation-shielding Mg-Ta-Al composites basing differential temperature hot rolling

A novel lightweight,radiation-shielding Mg-Ta-Al layered metal-matrix composite(LMC)was successful designed by doping the extremely refractory metal(Ta)into Mg sheets.These Mg-based LMCs sheets shows excellent radiation-dose shield effect,about 145 krad·a^(−1),which is about 17 times of traditional Mg alloy,while its surface density is only about 0.9 g·cm^(−2),reducing by 60%than that of pure Ta.The quantitate relationship between radiation-dose and the materials’thickness was also confirmed to the logistic function when the surface density is in the range of 0.6-1.5 g·cm^(−2).Meantime,the rolling parameters,interface microstructure and mechanical properties in both as-rolled and annealing treated samples were evaluated.The sheets possess a special dissimilar atoms diffusion transitional zone containing an obvious inter-diffusion Mg-Al interface and the unique micro-corrugated Ta-Al interface,as well as a thin Al film with a thickness of about 10μm.The special zone could reduce the stress concentration and enhance the strength of Mg-Ta-Al LMCs.The interface bonding strength reaches up to 54-76 MPa.The ultimate tensile strength(UTS)and yield strength(TYS)of the Mg-Ta-Al sheet were high to 413 MPa and 263 MPa,respectively,along with an elongation of 5.8%.The molecular dynamics(MD)analysis results show that the two interfaces exhibit different formation mechanism,the Mg-Al interface primarily depended on Mg/Al atoms diffusion basing point defects movement,while the Ta-Al interface with a micro-interlock pining shape formed by close-packed planes slipping during high temperature strain-induced deformation process.

Transmission and Dissipation of Vibration in a Dynamic Vibration Absorber-Roller System Based on Particle Damping Technology

The research of rolling mill vibration theory has always been a scientific problem in the field of rolling forming,which is very important to the quality of sheet metal and the stable operation of equipment.The essence of rolling mill vibration is the transfer of energy,which is generated from inside and outside.Based on particle damping technology,a dynamic vibration absorber(DVA)is proposed to control the vertical vibration of roll in the rolling process from the point of energy transfer and dissipation.A nonlinear vibration equation for the DVA-roller system is solved by the incremental harmonic balance method.Based on the obtained solutions,the effects of the basic parameters of the DVA on the properties of vibration transmission are investigated by using the power flow method,which provides theoretical guidance for the selection of the basic parameters of the DVA.Furthermore,the influence of the parameters of the particles on the overall dissipation of energy of the particle group is analyzed in a more systematic way,which provides a reference for the selection of the material and diameter and other parameters of the particles in the practical application of the DVA.The effect of particle parameters on roll amplitude inhibition is studied by experiments.The experimental results agree with the theoretical analysis,which proves the correctness of the theoretical analysis and the feasibility of the particle damping absorber.This research proposes a particle damping absorber to absorb and dissipate the energy transfer in rolling process,which provides a new idea for nonlinear dynamic analysis and stability control of rolling mills,and has important guiding significance for practical production.

A Novel Fractional Dengue Transmission Model in the Presence of Wolbachia Using Stochastic Based Artificial Neural Network

The purpose of this research work is to investigate the numerical solutions of the fractional dengue transmission model(FDTM)in the presence of Wolbachia using the stochastic-based Levenberg-Marquardt neural network(LM-NN)technique.The fractional dengue transmission model(FDTM)consists of 12 compartments.The human population is divided into four compartments;susceptible humans(S_(h)),exposed humans(E_(h)),infectious humans(I_(h)),and recovered humans(R_(h)).Wolbachia-infected and Wolbachia-uninfected mosquito population is also divided into four compartments:aquatic(eggs,larvae,pupae),susceptible,exposed,and infectious.We investigated three different cases of vertical transmission probability(η),namely when Wolbachia-free mosquitoes persist only(η=0.6),when both types of mosquitoes persist(η=0.8),and when Wolbachia-carrying mosquitoes persist only(η=1).The objective of this study is to investigate the effectiveness of Wolbachia in reducing dengue and presenting the numerical results by using the stochastic structure LM-NN approach with 10 hidden layers of neurons for three different cases of the fractional order derivatives(α=0.4,0.6,0.8).LM-NN approach includes a training,validation,and testing procedure to minimize the mean square error(MSE)values using the reference dataset(obtained by solving the model using the Adams-Bashforth-Moulton method(ABM).The distribution of data is 80% data for training,10% for validation,and,10% for testing purpose)results.A comprehensive investigation is accessible to observe the competence,precision,capacity,and efficiency of the suggested LM-NN approach by executing the MSE,state transitions findings,and regression analysis.The effectiveness of the LM-NN approach for solving the FDTM is demonstrated by the overlap of the findings with trustworthy measures,which achieves a precision of up to 10^(-4).

Review of the Configuration and Transient Stability of Large-scale Renewable Energy Generation through Hybrid DC Transmission

Based on the complementary advantages of Line Commutated Converter(LCC)and Modular Multilevel Converter(MMC)in power grid applications,there are two types of hybrid DC system topologies:one is the parallel connection of LCC converter stations and MMC converter stations,and the other is the series connection of LCC and MMC converter stations within a single station.The hybrid DC transmission system faces broad application prospects and development potential in large-scale clean energy integration across regions and the construction of a new power system dominated by new energy sources in China.This paper first analyzes the system forms and topological characteristics of hybrid DC transmission,introducing the forms and topological characteristics of converter-level hybrid DC transmission systems and system-level hybrid DC transmission systems.Next,it analyzes the operating characteristics of LCC and MMC inverter-level hybrid DC transmission systems,provides insights into the transient stability of hybrid DC transmission systems,and typical fault ride-through control strategies.Finally,it summarizes the networking characteristics of the LCC-MMC series within the converter station hybrid DC transmission system,studies the transient characteristics and fault ridethrough control strategies under different fault types for the LCC-MMC series in the receiving-end converter station,and investigates the transient characteristics and fault ride-through control strategies under different fault types for the LCC-MMC series in the sending-end converter station.