A Coupled Thermomechanical Crack Propagation Behavior of Brittle Materials by Peridynamic Differential Operator

This study proposes a comprehensive,coupled thermomechanical model that replaces local spatial derivatives in classical differential thermomechanical equations with nonlocal integral forms derived from the peridynamic differential operator(PDDO),eliminating the need for calibration procedures.The model employs a multi-rate explicit time integration scheme to handle varying time scales in multi-physics systems.Through simulations conducted on granite and ceramic materials,this model demonstrates its effectiveness.It successfully simulates thermal damage behavior in granite arising from incompatible mineral expansion and accurately calculates thermal crack propagation in ceramic slabs during quenching.To account for material heterogeneity,the model utilizes the Shuffle algorithm andWeibull distribution,yielding results that align with numerical simulations and experimental observations.This coupled thermomechanical model shows great promise for analyzing intricate thermomechanical phenomena in brittle materials.

An extended micromechanical-based plastic damage model for understanding water effects on quasi-brittle rocks

Water effects on the mechanical properties of rocks have been extensively investigated through experiments and numerical models.However,few studies have established a comprehensive link between the microscopic mechanisms of water-related micro-crack and the constitutive behaviors of rocks.In this work,we shall propose an extended micromechanical-based plastic damage model for understanding weakening effect induced by the presence of water between micro-crack’s surfaces on quasi-brittle rocks,based on the Mori-Tanaka homogenization and irreversible thermodynamics framework.Regarding the physical mechanism,water strengthens micro-crack propagation,which induces damage evolution during the pre-and post-stage,and weakens the elastic effective properties of rock matrix.After proposing a special calibration procedure for the determination of model parameters based on the laboratory compression tests,the proposed micromechanical-based model is verified by comparing the model predictions to the experimental results.The model effectively captures the mechanical behaviors of quasibrittle rocks subjected to the weakening effects of water.

The Application of“Problem-Based Learning+Flipped Classroom”Teaching Model in Bilingual Education

This study focuses on the application of the“PBL(problem-based learning)+Flipped Classroom”teaching model in bilingual education,aiming to explore its potential to enhance the quality and effectiveness of bilingual teaching.PBL emphasizes learning through the resolution of real-world problems,while the Flipped Classroom advocates that students acquire basic knowledge through self-study before class,dedicating class time to in-depth discussions and practical activities.The integration of these two teaching models in bilingual education aims to stimulate students’interest in learning,improve their autonomous learning abilities,enhance critical thinking,and foster cross-cultural communication skills.Through literature review,case analysis,and empirical research,this study first examines the current applications and challenges of PBL and the Flipped Classroom in bilingual education.Subsequently,it elaborates on the specific implementation steps of the“PBL+Flipped Classroom”teaching model in bilingual education,including problem design,preview material provision,cooperative learning,classroom activities,and language support.A comparative experiment is then conducted to analyze the impact of this teaching model on students’learning motivation,academic performance,and cross-cultural communication skills.The results indicate that the“PBL+Flipped Classroom”teaching model significantly improves students’learning motivation and participation,enhances academic performance,and effectively boosts their cross-cultural communication skills.Furthermore,this model aids in cultivating students’autonomous learning abilities and critical thinking,providing an innovative and effective approach to bilingual education.This study offers new ideas and insights for the field of bilingual education,which is of great significance for promoting the innovation and development of bilingual teaching models.

云计算中基于模糊聚类的资源调度的应用研究

目前大多数云计算数据中心在资源分配过程中没有充分考虑作业的性能代价问题,采用一种改进的云计算资源分配策略,建立并行任务性能代价模型,利用改进的模糊聚类算法(CBFCM Cost-Based Fuzzy Clustering Algorithm)对云计算资源集进行分组,根据用户服务等级USL进行调度,采用四种资源调度算法进行分析。实验结果表明,采用CBFCM算法对云计算资源进行分类后,AFCFS算法与其他算法相比,可以减少作业响应时间和作业等待时间。

Porosity and permeability variations of a dam curtain during dissolution

During reservoir operation,the erosion effects of groundwater change the porosity and permeability of the dam curtain,causing changes to the seepage field.To understand where the changes take place and to what degree the porosity and permeability change,a multi-field coupling model was built and solved.The model takes into account seepage,solution concentration,and solid structure.The model was validated using uplift pressure monitoring data.Then,the variations in curtain porosity,seepage flow,and loss quantity of Ca(OH)2 were calculated.The key time nodes were obtained through curve fitting of the variation of seepage flow with the BiDoseResp function.The results showed that the model could reflect the attenuation trend of curtain performance well.The process and position of the erosion were not homogeneous.Although erosion mainly occurred at the top and bottom of the curtain,it was most developed at the top.The erosion effects developed slowly during the early stage,much fast during the middle and late stages,and culminated in complete dissolution.The model results and the daily monitoring data can provide a scientific basis for the safe operation and management of reservoirs.

Quantitative analysis of the effect of the PAY1 gene on rice canopy structure during different reproductive stages

The leaf and stem types are core structural characteristics of the rice phenotype that determine the light interception ability of the canopy and directly affect crop yield.The PLANT ARCHITECTURE AND YIELD 1(PAY1)gene has been shown to alter the prostrate growth habit of wild rice and to inhibit the wild rice prostrate growth gene PROSTRATE GROWTH 1(PROG1).In this paper,the wild rice introgression line YIL55,which contains the PROG1 gene;its mutant,PAY1;and its parent,TQ,were used as test varieties to construct three-dimensional(3D)canopy structure models based on 3D digital assay technology.On this basis,quantitative analyses of the PAY1 gene and the plant leaf and stem types at the jointing,heading and filling stages were performed.Under the influence of the PAY1 gene,the plant stem and leaf angles from vertical decreased significantly;the plants were upright,with larger leaves;the culm angle changed from loose to compact;and the average tiller angle during the three key reproductive stages decreased from 44.9,28.5 and 21.3°to 17.6,8.4 and 10.5°,respectively.Moreover,the PAY1 mutant retained the PROG1 gene characteristic of exhibiting dynamic changes in the tiller angle throughout the growth period,and its culm angle changed from loose during the jointing stage to compact during the heading stage.The measurements of photosynthetically active radiation(PAR)in the canopy also showed that the mutant PAY1 allowed more PAR to reach the bottom of the canopy than the other varieties.The light-extinction coefficients for PAY1 at the jointing,heading and filling stages were 0.535,0.312 and 0.586,respectively,which were lower than those of the other two varieties.In this study,the influence of the PAY1 gene on rice canopy structural characteristics was quantitatively analyzed to provide effective canopy structure parameters for breeding the ideal plant type.

ConvLSTM Based Temperature Forecast Modification Model for North China

The correction of model forecast is an important step in evaluating weather forecast results.In recent years,post-processing models based on deep learning have become prominent.In this paper,a deep learning model named EDConvLSTM based on encoder-decoder structure and ConvLSTM is developed,which appears to be able to effectively correct numerical weather forecasts.Compared with traditional post-processing methods and convolutional neural networks,ED-ConvLSTM has strong collaborative extraction ability to effectively extract the temporal and spatial features of numerical weather forecasts and fit the complex nonlinear relationship between forecast field and observation field.In this paper,the post-processing method of ED-ConvLSTM for 2 m temperature prediction is tested using The International Grand Global Ensemble dataset and ERA5-Land data from the European Centre for Medium-Range Weather Forecasts(ECMWF).Root mean square error and temperature prediction accuracy are used as evaluation indexes to compare ED-ConvLSTM with the method of model output statistics,convolutional neural network postprocessing methods,and the original prediction by the ECMWF.The results show that the correction effect of EDConvLSTM is better than that of the other two postprocessing methods in terms of the two indexes,especially in the long forecast time.

The effects of co-utilizing green manure and rice straw on soil aggregates and soil carbon stability in a paddy soil in southern China

The co-utilization of green manure (GM) and rice straw (RS) in paddy fields has been widely applied as an effective practice in southern China.However,its effects on soil aggregate and soil organic carbon (SOC) stability remain unclear.In the present study,the effect of GM,RS,and co-utilization of GM and RS on particle size distribution of soil aggregates and SOC density fractions were measured in a field experiment.The experiment included six treatments,i.e.,winter fallow (WF) without RS return (Ctrl),WF with 50%RS return (1/2RS),WF with 100%RS return (RS),GM without RS return (GM),GM with 50%RS return (GM1/2RS) and GM with 100%RS return (GMRS).The results showed that the proportion of small macro-aggregates (0.25–2 mm) and the mean weight diameter (MWD) of aggregates in the GMRS treatment was greater (by 18.9 and 3.41%,respectively) than in the RS treatment,while the proportion of silt+clay particles (<0.053 mm) was lower (by 14.4%).The concentration of SOC in microaggregates (0.053–0.25 mm)and silt+clay particles was higher in the GMRS treatment than in GM and RS treatments individually.The concentration and proportion of free light organic carbon (fLOC) in aggregates of various particle sizes and bulk soil was greater in the GMRS treatment than the RS treatment,whereas the concentration and proportion of mineral-associated organic carbon in small macroaggregates,microaggregates,and bulk was lower in the GMRS treatment than in the RS treatment.The proportion of intra-aggregate particulate organic carbon (iPOC) was greater in the GMRS treatment than in GM treatment.The GMRS treatment had strong positive effects on iPOC in small macroaggregates,suggesting that SOC was transferred from fLOC to iPOC.In conclusion,co-utilizing green manure and rice straw cultivated the SOC pool by increasing the concentration of fLOC and improved soil carbon stability by promoting the sequestration of organic carbon in iPOC as a form of physical protection.

A Trusted Multi-Task Distribution Mechanism for Internet of Vehicles Based on Smart Contract

In this paper,a trusted multi-task distribution mechanism for Internet of Vehicles based on smart contract is proposed to improve the security and efficiency for the task distribution in Internet of Vehicles.Firstly,a three-tier trusted multi-task distribution framework is presented based on smart contract.The smart contract will be triggered by the task request.As the important part of the smart contract,the task distribution algorithm is stored on the blockchain and run automatically.In the process of the task distribution,the cost of the task distribution and the system stability play a critical role.Therefore,the task distribution problem is formulated to minimize the cost of the task distribution whilst maintaining the stability of the system based on Lyapunov theorem.Unfortunately,this problem is a mixed integer nonlinear programming problem with NP-hard characteristics.To tackle this,the optimization problem is decomposed into two sub problems of computing resource allocation and task distribution decision,and an effective task distribution algorithm is proposed.Simulation results show that the proposed algorithm can effectively improves system performance.

Numerical Analysis on the Seismic Performance of Plane Irregular Structure Based on ABAQUS

Rod element and shell element were used in finite element software ABAQUS to establish dynamic elastic-plastic analysis model of the structure,the seismic performance of an irregular plane complex overrun structure numerical simulation,the structure was calculated under different input level and displacement response of the acceleration response,and analyses the force of the wear layer column and the floor of the open hole stress level.The results were compared with the shaking table test to verify the accuracy of the numerical simulation results.The results of numerical calculation were basically consistent with the experimental results,and the finite element model basically reflected the response of the structure under the simulated earthquake.

大学英语教学研究的生态语言学视角

生态语言学关注语言学习的动态性和系统性,为语言教学研究提供了新的视角并为其教学模式的构建提供了积极的理论支持,对改变中国大学英语教学现状具有一定的启示作用。本研究从生态语言学视角,将语言的教与学过的程视为一个微观生态系统,对英语教学进行全面的动态研究,从多角度研究学习者、教师、语言和学习环境之间的系统互动。从教学目标、教学内容、教学方法、教学评价体系等方面对英语教学进行生态设计,以改进大学英语教学方法,提高大学英语学习者的学习效率。

Application of BIM Technology in Rapid Modeling of Residential Building Design

Combining with engineering examples,this paper introduces BIM into architectural design model and adopts Revit rapid modeling.It focuses on realizing rapid combination modeling of similar components through secondary development,improving information conversion efficiency between engineering CAD and Revit building structure modeling,and quickly generating BIM structure construction drawings.

Research on the Abilities of Community Education Study Tour Instructors

Community education study tour instructors are important action elements of community education tours.It is necessary to sort out the abilities of community education study tour instructors as well as construct a scientific and reasonable professional ability index system for community education study tour instructors,so as to promote the high-quality development of community education as well as the modernization of lifelong education governance system and governance ability.Based on the practice of community education in Jiangsu and the basic theory of pedagogy,this paper puts forward five core vocational abilities of community education,including travel education and teaching ability,curriculum development ability,management and research ability,training and guidance ability,as well as study tour guarantee ability.This paper attempts to sort out the ability of community education study tour instructors through research and analysis.A three-dimensional and multi-dimensional framework of community education instructors’ability has been constructed to provide a path for the professional development of community education study tour instructors.

In Situ Liquid Cell Transmission Electron Microscopy Observations of Growth and Anticorrosion Behaviors of AuCl3 Shell on Au Nanobipyramids

Comprehensive Summary Designing new materials and architectures to maintain activity and stability requires a better understanding on the anticorrosion dynamics of nanoparticles.Under-coordinated atoms on the surface of nanoparticles can be protected by deposited shells.Real-time observation on how protective shells grow and play a role is challenging but worthwhile.Here,protective effects of AuCl_(3) shells on Au nanobipyramids(NBPs)are studied in HAuCl_(4) aqueous solutions by in-situ liquid cell transmission electron microscopy(LCTEM).This study is the first to observe the formation of Au-AuCl_(3) core-shell nanostructure and the corresponding anticorrosion behaviors of AuCl_(3) deposited shell.The presence of CTAB can substantially influence the growth mode and structure of AuCl_(3) shell,by a direct or indirect way,intervene the dissolution of Au NBP.These growth or dissolution kinetics here revealed at the nanoscale provide insights towards engineering of the surface anticorrosion to pursue Au nanoparticles with improved stability in acidic environment.

Room-temperature ferromagnetism and piezoelectricity in metalfree 2D semiconductor crystalline carbon nitride

Two-dimensional(2D)materials that combine ferromagnetic,semiconductor,and piezoelectric properties hold significant potential for both fundamental research and spin electronic devices.However,the majority of reported 2D ferromagnetic-semiconductor-piezoelectric materials rely on d-electron systems,which limits their practical applications due to a Curie temperature lower than room temperature(RT).Here,we report a high-crystallinity carbon nitride(CCN)material based on sp-electrons using a chemical vapor deposition strategy.CCN exhibits a band gap of 1.8 eV and has been confirmed to possess substantial in-plane and out-of-plane piezoelectricity.Moreover,we acquired clear evidences of ferromagnetic behavior at room temperature.Extensive structural characterizations combined with theoretical calculations reveal that incorporating structural oxygen into the highly ordered heptazine structure causes partial substitution of nitrogen sites,which is primarily responsible for generating room-temperature ferromagnetism and piezoelectricity.As a result,the strain in wrinkles can effectively modulate the domain behavior and piezoelectric potential at room temperature.The addition of RT ferromagnetic-semiconductor-piezoelectric material based on sp-electrons to the family of two-dimensional materials opens up numerous possibilities for novel applications in fundamental research and spin electronic devices.

A fault diagnosis model based on weighted extension neural network for turbo-generator sets on small samples with noise

In data-driven fault diagnosis for turbo-generator sets,the fault samples are usually expensive to obtain,and inevitably with noise,which will both lead to an unsatisfying identification performance of diagnosis models.To address these issues,this paper proposes a fault diagnosis model for turbo-generator sets based on Weighted Extension Neural Network(W-ENN).WENN is a novel neural network which has three types of connection weights and an improved correlation function.The performance of the proposed model is validated against Extension Neural Network(ENN),Support Vector Machine(SVM),Relevance Vector Machine(RVM)and Extreme Learning Machine(ELM)based models.The results indicate that,on noisy small sample sets,the proposed model is superior to the other models in terms of higher identification accuracy with fewer samples and strong noise-tolerant ability.The findings of this study may serve as a powerful fault diagnosis model for turbo-generator sets on noisy small sample sets.

Flexural and longitudinal shear performance of precast lightweight steel-ultra-high performance concrete composite beam

In this study,the flexural and longitudinal shear performances of two types of precast lightweight steel–ultra-high performance concrete(UHPC)composite beams are investigated,where a cluster UHPC slab(CUS)and a normal UHPC slab(NUS)are connected to a steel beam using headed studs through discontinuous shear pockets and full-length shear pockets,respectively.Results show that the longitudinal shear force of the CUS is greater than that of the NUS,whereas the interfacial slip of the former is smaller.Owing to its better integrity,the CUS exhibits greater flexural stiffness and a higher ultimate bearing capacity than the NUS.To further optimize the design parameters of the CUS,a parametric study is conducted to investigate their effects on the flexural and longitudinal shear performances.The square shear pocket is shown to be more applicable for the CUS,as the optimal spacing between two shear pockets is 650 mm.Moreover,a design method for transverse reinforcement is proposed;the transverse reinforcement is used to withstand the splitting force caused by studs in the shear pocket and prevent the UHPC slab from cracking.According to calculation results,the transverse reinforcement can be canceled when the compressive strength of UHPC is 150 MPa and the volume fraction of steel fiber exceeds 2.0%.

Heating properties of bridge decks using hydronic heating systems with internal or external circulation tubes

A comparison analysis of the heating properties of the hydronic heating system of bridge decks with external(exchange tubes installed at the bottom of the existing bridge deck with voids inside)or internal(exchange tubes embedded in pavement of the newly built bridge deck)tubes was carried out through field tests.Two heating methods(constant heating power and constant inlet fluid temperature)were used to analyze the heat exchange flux and the temperature increments as well as thermally induced stress of the slab.Numerical simulation was conducted to model the bridge deck heating process to analyze the temperature distribution of the bridge surface.The results shows that the heat exchange flux are the same under the same constant heating powers for the two embedded tube position heating systems;the maximum temperature increment of the bridge deck surface obtained by the external heating system is 0.46 times that obtained by the internal heating system;the maximum thermally induced stress caused by the external heating is 20.4%of the concrete strength(19.1 MPa),which is much higher than that caused by the internal heating under the same heating powers.The thermal efficiencies of the external and internal heating systems are approximately 24.4%and 47.9%,respectively.Under the same constant inlet temperatures,the temperature increment of the bridge deck caused by the external heating is 20.4%of that of the internal heating.