The efficiency and stability of catalysts for photocatalytic hydrogen evolution(PHE)are largely governed by the charge transfer behaviors across the heterojunction interfaces.In this study,CuO,a typical semiconductor ...The efficiency and stability of catalysts for photocatalytic hydrogen evolution(PHE)are largely governed by the charge transfer behaviors across the heterojunction interfaces.In this study,CuO,a typical semiconductor featuring a broad spectral absorption range,is successfully employed as the electron acceptor to combine with CdS for constructing a S-scheme heterojunction.The optimized photocatalyst(CdSCuO2∶1)delivers an exceptional hydrogen evolution rate of 18.89 mmol/(g·h),4.15-fold higher compared with bare CdS.X-ray photoelectron spectroscopy(XPS)and ultraviolet-visible diffuse reflection absorption spectroscopy(UV-vis DRS)confirmed the S-scheme band structure of the composites.Moreover,the surface photovoltage(SPV)and electron paramagnetic resonance(EPR)indicated that the photogenerated electrons and photogenerated holes of CdS-CuO2∶1 were respectively transferred to the conduction band(CB)of CdS with a higher reduction potential and the valence band(VB)of CuO with a higher oxidation potential under illumination,as expected for the S-scheme mechanism.Density-functional-theory calculations of the electron density difference(EDD)disclose an interfacial electric field oriented from CdS to CuO.This built-in field suppresses charge recombination and accelerates carrier migration,rationalizing the markedly enhanced PHE activity.This study offers a novel strategy for designing S-scheme heterojunctions with high light harvesting and charge utilization toward sustainable solar-tohydrogen conversion.展开更多
Directional three-dimensional carbon-based foams are emerging as highly attractive candidates for promising electromagnetic wave absorbing materials(EWAMs)thanks to their unique architecture,but their construction usu...Directional three-dimensional carbon-based foams are emerging as highly attractive candidates for promising electromagnetic wave absorbing materials(EWAMs)thanks to their unique architecture,but their construction usually involves complex procedures and extremely depends on unidirectional freezing technique.Herein,we propose a groundbreaking approach that leverages the assemblies of salting-out protein induced by ammonium metatungstate(AM)as the precursor,and then acquire directional three-dimensional carbon-based foams through simple pyrolysis.The electrostatic interaction between AM and protein ensures well dispersion of WC_(1−x)nanoparticles on carbon frameworks.The content of WC_(1−x)nanoparticles can be rationally regulated by AM dosage,and it also affects the electromagnetic(EM)properties of final carbon-based foams.The optimized foam exhibits exceptional EM absorption performance,achieving a remarkable minimum reflection loss of−72.0 dB and an effective absorption bandwidth of 6.3 GHz when EM wave propagates parallel to the directional pores.Such performance benefits from the synergistic effects of macroporous architecture and compositional design.Although there is a directional dependence of EM absorption,radar stealth simulation demonstrates that these foams can still promise considerable reduction in radar cross section with the change of incident angle.Moreover,COMSOL simulation further identifies their good performance in preventing EM interference among different electronic components.展开更多
Developing deep fragmented soft coalbed methane(CBM)can significantly enhance domestic natural gas supplies,reduce reliance on imported energy,and bolster national energy security.This manuscript provides a comprehens...Developing deep fragmented soft coalbed methane(CBM)can significantly enhance domestic natural gas supplies,reduce reliance on imported energy,and bolster national energy security.This manuscript provides a comprehensive review of commonly employed coalbed methane extraction technologies.It then delves into several critical issues in the current stage of CBM exploration and development in China,including the compatibility of existing technologies with CBM reservoirs,the characteristics and occurrence states of CBM reservoirs,critical desorption pressure,and gas generation mechanisms.Our research indicates that current CBM exploration and development technologies in China have reached an internationally advanced level,yet the industry is facing unprecedented challenges.Despite progress in low-permeability,high-value coal seams,significant breakthroughs have not been achieved in exploring other types of coal seams.For different coal reservoirs,integrated extraction technologies have been developed,such as surface pre-depressurisation and segmented hydraulic fracturing of coal seam roof strata.Additionally,techniques like large-scale volume fracturing in horizontal wells have been established,significantly enhancing reservoir stimulation effects and coalbed methane recovery rates.However,all of these technologies are fundamentally based on permeation.These technologies lack direct methods aimed at enhancing the diffusion rate of CBM,thereby failing to fully reflect the unique characteristics of CBM.Current CBM exploration and development theories and technologies are not universally applicable to all coal seams.They do not adequately account for the predominantly adsorbed state of CBM,and the complex and variable gas generation mechanisms further constrain CBM development in China.Finally,continuous exploration of new deep CBM exploration technologies is necessary.Integrating more effective reservoir stimulation technologies is essential to enhance technical adaptability concerning CBM reservoir characteristics,gas occurrence states,and gas generation mechanisms,ultimately achieving efficient CBM development.We conclude that while China possesses a substantial foundation of deep fractured CBM resources,industry development is constrained and requires continuous exploration of new CBM exploration and development technologies to utilize these resources effectively.展开更多
Aiming at mitigating the high risks associated with conventional explosive blasting,this study developed a safe directional fracturing technique,i.e.instantaneous expansion with a single fracture(IESF),using a coal-ba...Aiming at mitigating the high risks associated with conventional explosive blasting,this study developed a safe directional fracturing technique,i.e.instantaneous expansion with a single fracture(IESF),using a coal-based solid waste expanding agent.First,the mechanism of directional fracturing blasting by the IESF was analyzed,and the criterion of directional crack initiation was established.On this basis,laboratory experiments and numerical simulations were conducted to systematically evaluate the directional fracturing blasting performance of the IESF.The results indicate that the IESF presents an excellent directional fracturing effect,with average surface undulation differences ranging from 8.1 mm to 22.7 mm on the fracture surfaces.Moreover,during concrete fracturing tests,the stresses and strains in the fracturing direction are measured to be 2.16-3.71 times and 8 times larger than those in the nonfracturing direction,respectively.Finally,the IESF technique was implemented for no-pillar mining with gob-side entry retaining through roof cutting and pressure relief in an underground coal mine.The IESF technique effectively created directional cracks in the roof without causing severe roadway deformation,achieving an average cutting rate and maximum roadway deformation of 94%and 197 mm,respectively.These on-site test results verified its excellent directional rock fracturing performance.The IESF technique,which is safe,efficient,and green,has considerable application prospects in the field of rock mechanics and engineering.展开更多
To investigate the effects of the maximum principal stress direction(θ)and cross-section shape on the failure characteristics of sandstone,true-triaxial compression experiments were conducted using cubic samples with...To investigate the effects of the maximum principal stress direction(θ)and cross-section shape on the failure characteristics of sandstone,true-triaxial compression experiments were conducted using cubic samples with rectangular,circular,and D-shaped holes.Asθincreases from 0°to 60°in the rectangular hole,the left failure location shifts from the left corner to the left sidewall,the left corner,and then the floor,while the right failure location shifts from the right corner to the right sidewall,right roof corner,and then the roof.Furthermore,the initial failure vertical stress first decreases and then increases.In comparison,the failure severity in the rectangular hole decreases for variousθvalues as 30°>45°>60°>0°.With increasingθ,the fractal dimension(D)of rock slices first increases and then decreases.For the rectangular and D-shaped holes,whenθ=0°,30°,and 90°,D for the rectangular hole is less than that of the D-shaped hole.Whenθ=45°and 60°,D for the rectangular hole is greater than that of the D-shaped hole.Theoretical analysis indicates that the stress concentration at the rectangular and D-shaped corners is greater than the other areas.The failure location rotates with the rotation ofθ,and the failure occurs on the side with a high concentration of compressive stress,while the side with the tensile and compressive stresses remains relatively stable.Therefore,the fundamental reason for the rotation of failure location is the rotation of stress concentration,and the external influencing factor is the rotation ofθ.展开更多
To enhance the recuperation rate of the mine and comply with the stipulations of green mining technology, it is vital to expeditiously recuperate the coal pillar resources in the final stage, thus preventing the consi...To enhance the recuperation rate of the mine and comply with the stipulations of green mining technology, it is vital to expeditiously recuperate the coal pillar resources in the final stage, thus preventing the considerable squandering of resources. The coal pillar resource of the main roadway and its branch roadway constitutes a significant recovery subject. Its coal pillar shape is regular and possesses a considerable strike distance, facilitating the arrangement of the coal pillar recovery working face (CPRWF) for mining operations. However, for the remaining coal pillars with a thick and hard roof (THF) and multiple tectonic zones, CPRWF encounters challenges in selecting an appropriate layout, managing excessive roof pressure, and predicting mining stress. Aiming at the roadway coal pillar group with THF and multi-structural areas in specific projects, a method of constructing multi-stage CPRWF by one side gob-side entry driving (GSED) and one side roadway reusing is proposed. Through theoretical calculation of roof fracture and numerical simulation verification, combined with field engineering experience and economic analysis, the width of the narrow coal pillar (NCP) in the GSED is determined to be 10 m and the length of the CPRWF is 65 m. Concurrently, the potential safety hazard that the roof will fall asymmetrically and THF is difficult to break during CPRWF mining after GSED is analyzed and verified. Then, a control method involving the pre-cutting of the roof in the reused roadway before mining is proposed. This method has been shown to facilitate the complete collapse of THF, reduce the degree of mine pressure, and facilitate the symmetrical breaking of the roof. Accordingly, a roof-cutting scheme based on a directional drilling rig, bidirectional shaped polyvinyl chloride (PVC) pipe, and emulsion explosive was devised, and the pre-splitting of 8.2 m THF was accomplished. Field observations indicate that directional cracks are evident in the roof, the coal wall is flat during CPRWF mining, and the overall level of mining pressure is within the control range. Therefore, the combined application of GSED and roof-cutting technology for coal pillar recovery has been successfully implemented, thereby providing new insights and engineering references for the construction and pressure relief mining of CPRWF.展开更多
Accuracy allocation is crucial in the accuracy design of machining tools.Current accuracy allocation methods primarily focus on positional deviation,with little consideration for tool direction deviation.To address th...Accuracy allocation is crucial in the accuracy design of machining tools.Current accuracy allocation methods primarily focus on positional deviation,with little consideration for tool direction deviation.To address this issue,we propose a geometric error cost sensitivity-based accuracy allocation method for five-axis machine tools.A geometric error model consisting of 4l error components is constructed based on homogeneous transformation matrices.Volumetric points with positional and tool direction deviations are randomly sampled to evaluate the accuracy of the machine tool.The sensitivity of each error component at these sampling points is analyzed using the Sobol method.To balance the needs of geometric precision and manufacturing cost,a geometric error cost sensitivity function is developed to estimate the required cost.By allocating error components affecting tool direction deviation first and the remaining components second,this allocation scheme ensures that both deviations meet the requirements.We also perform numerical simulation of a BC-type(B-axis and C-axis type)five-axis machine tool to validate the method.The results show that the new allocation scheme reduces the total geometric error cost by 27.8%compared to a uniform allocation scheme,and yields the same positional and tool direction machining accuracies.展开更多
Professor Paul Crosthwaite,from the School of Literature,Languages,and Cultures at the University of Edinburgh,is a prominent scholar in the interdisciplinary field of literature and economics.He is a co-editor of the...Professor Paul Crosthwaite,from the School of Literature,Languages,and Cultures at the University of Edinburgh,is a prominent scholar in the interdisciplinary field of literature and economics.He is a co-editor of the Palgrave Studies in Literature,Culture,and Economics series and The Cambridge Companion to Literature and Economics(2022).In recent years,he has significantly influenced the intersection of literature and economics,advocating particularly for a shift towards the Economic Humanities.This interview covers:1.The definition and theoretical origin of the Economic Humanities;2.The internal heterogeneity and critical limitations of the New Economic Criticism,and the theoretical advantages and potential development of the Economic Humanities;3.What research paradigms do Environmental Humanities,Medical Humanities,and Digital Humanities provide for the Economic Humanities;4.How literary researchers can work at the interface of the Economic Humanities research.As a novel interdisciplinary interface between literature and economics,Professor Paul Crosthwaite’s concept of the Economic Humanities not only pioneers methodological tools for interdisciplinary studies of literature and economics but also underscores the interpretative potential and disciplinary benefits of literary viewpoints on economics.This underscores the vital role of literature in human knowledge,meriting attention from the literary research academia.展开更多
According to the measurement principle of the traditional interferometer,a narrowband signal model is established and used,however,for wideband signals or multiple signals,this model is invalid.For the problems of dir...According to the measurement principle of the traditional interferometer,a narrowband signal model is established and used,however,for wideband signals or multiple signals,this model is invalid.For the problems of direction finding with interferometer for wideband signals and multiple signals scene,a frequency domain phase interferometer is proposed and the concrete implementation scheme is given.The proposed method computes the phase difference in frequency domain,and finds multi-target results with judging the spectrum amplitude changing,and uses the frequency phase difference to compute the arrival angle.Theoretical analysis and simulation results show that the proposed method effectively solves the problem of the angle estimation with phase interferometer for wideband signals,and has good performance in multiple signals scene with nonoverlapping spectrum or partially overlapping.In addition,the wider the signal bandwidth,the better direction finding performance of this algorithm.展开更多
Interval-valued pre-aggregation functions are a hot topic in the research of aggregation functions and have received considerable attention in recent years.As a special class of interval-valued pre-aggregation functio...Interval-valued pre-aggregation functions are a hot topic in the research of aggregation functions and have received considerable attention in recent years.As a special class of interval-valued pre-aggregation functions,(light)interval-valued pre-t-norms were initially proposed by Wang and Hu,but their properties were not further discussed by the authors.The main purpose of this paper is to study in depth the properties and generation of(light)intervalvalued pre-t-norms.Firstly,several properties of(light)interval-valued pre-t-norms and their relationship with(light)pre-t-norms are presented.Then,two different generation methods for(light)interval-valued pre-t-norms are introduced.Finally,it demonstrates a specific application of(light)interval-valued pre-t-norms in constructing interval-valued directional monotonic fuzzy implications,namely,using the(light)interval-valued pre-t-norm IT,interval-valued fuzzy negations IN,and(light)interval-valued pre-t-conorm IS to construct interval-valued QL-directional monotonic operations.展开更多
Columnar grains offer considerable advantages in terms of microstructure for resisting high-temperature low-cycle fatigue. In additive manufacturing, the formation of fine columnar grains is common. However, post-heat...Columnar grains offer considerable advantages in terms of microstructure for resisting high-temperature low-cycle fatigue. In additive manufacturing, the formation of fine columnar grains is common. However, post-heat treatment often transforms these grains into equiaxed grains. This study aimed to tailor the grain morphology by controlling the precipitation of carbides. By balancing the restraining effects of carbide pinning and grain growth, we achieved carbide-assisted in situ-directional recrystallization. This process preserved the columnar grains created via laser powder bed fusion, even after high-temperature heat treatment. The approach emphasizes promoting the longitudinal growth of columnar grains while preventing their broadening. Additionally, we characterized the evolution of carbides and γ′ precipitates and examined their role in nucleation and growth during recrystallization. This study supports the viability of carbide-assisted in situ-directional recrystallization in additive manufacturing alloys, introducing an innovative strategy for microstructure customization. The implementation of carbon stabilization (CS) treatment to control the carbide distribution led to a 40 % improvement in the creep life at 900 ℃ and 150 MPa.展开更多
Mental healthcare in Ethiopia is underutilized due to a lack of resources and skilled practitioners.Psychological counselling offers unique intervention possibilities because of its focus on a wide range of mental hea...Mental healthcare in Ethiopia is underutilized due to a lack of resources and skilled practitioners.Psychological counselling offers unique intervention possibilities because of its focus on a wide range of mental health and social justice issues.This literature review tracks the historical development of the profession of psychological counselling in Ethiopia to establish what has been achieved to date and the development challenges.Key achievements include recognition of the profession by the Ministry of Education,growing public awareness,and increasing capacity of practitioners skilled in psychological counselling.Challenges include limited contextually relevant training,poor representation of the profession within Ministry of Health policies,poor public and government mental health literacy,and a lack of regulatory frameworks.Postgraduate training would benefit from more culturally,contextually,and linguistically appropriate evidence-based,indigenous psychology practices.The profession would benefit from engagement in government policy development that promotes mental health,and professional regulatory bodies to hold practitioners accountable to professional standards and ethical practice.展开更多
Aiming at the problem that infrared small target detection faces low contrast between the background and the target and insufficient noise suppression ability under the complex cloud background,an infrared small targe...Aiming at the problem that infrared small target detection faces low contrast between the background and the target and insufficient noise suppression ability under the complex cloud background,an infrared small target detection method based on the tensor nuclear norm and direction residual weighting was proposed.Based on converting the infrared image into an infrared patch tensor model,from the perspective of the low-rank nature of the background tensor,and taking advantage of the difference in contrast between the background and the target in different directions,we designed a double-neighborhood local contrast based on direction residual weighting method(DNLCDRW)combined with the partial sum of tensor nuclear norm(PSTNN)to achieve effective background suppression and recovery of infrared small targets.Experiments show that the algorithm is effective in suppressing the background and improving the detection ability of the target.展开更多
Microporosity formed in the solidification process of Al alloys is detrimental to the alloy properties.A two-dimensional cellular automaton(CA)model was developed to simulate the microstructure and microporosity forma...Microporosity formed in the solidification process of Al alloys is detrimental to the alloy properties.A two-dimensional cellular automaton(CA)model was developed to simulate the microstructure and microporosity formation in Al-Cu alloys,considering variations in Cu content and solidification rate.The results indicate that the Cu content primarily influences the growth of microporosity.To validate the model,directional solidification experiments were conducted on Al-Cu alloys with varing Cu contents and withdrawal rates.The experimental results of dendrites and microporosity characteristics agree well with the predictions from the developed model,thus confirming the validity of the model.The alloy’s liquidus temperature,dendrite morphology,and hydrogen saturation solubility arising from different Cu contents have significant effects on microporosity morphology.The withdrawal rate primarily affects the nucleation of hydrogen microporosity by altering cooling rates and dendritic growth rates,resulting in different microporosity characteristics.展开更多
Direct propane dehydrogenation(DPDH)represents a highly attractive route for on-purpose propylene production,a key building block in the petrochemical industry.In particular,among various catalytic platforms,vanadium-...Direct propane dehydrogenation(DPDH)represents a highly attractive route for on-purpose propylene production,a key building block in the petrochemical industry.In particular,among various catalytic platforms,vanadium-based catalysts have emerged as promising candidates due to their tunable properties including redox ability,surface acidity,and resistance to coking.Although the catalytic community has obtained great achievement in this area,how to promote vanadium-based catalysts towards the next step in DPDH applications like industrial-level implementations is still challenging.Moreover,there are still several controversial theories in our community,meaning it is necessary to clarify these indistinct points to pave the way for the next generation of research.Herein,the pivotal modification strategies of vanadium-based catalysts have been summarized via introducing representative works.In addition,the current unclear mechanism and research gaps,especially in the issues of deactivation and selectivity control,are also revealed so that the potential research directions are well-founded proposed.By integrating fundamental understanding and practical considerations,this review aims to inspire the further development of vanadium-based DPDH catalysts for in-depth academic research and next-generation industrial deployment.展开更多
Passive imaging through intense atmospheric scattering is a critical yet formidable challenge in optical imaging,with profound implications across various applications.Conventional cameras struggle under severe scatte...Passive imaging through intense atmospheric scattering is a critical yet formidable challenge in optical imaging,with profound implications across various applications.Conventional cameras struggle under severe scattering conditions,fundamentally limiting their effectiveness.We propose a groundbreaking directional atmospheric scattering model that revolutionizes passive imaging capabilities,converting a conventional camera to a super-camera.The model precisely characterizes directional photon propagation through scattering media,transforming this historically ill-posed problem into a well-posed solution,based on which a 4D spatial-angular scattering reconstruction method is proposed,which leverages both ballistic photons and directionally resolved scattered light,without relying on any scene-specific priors,to achieve unprecedented passive imaging performance enabling color imaging through over 12 transport mean free paths at distances up to 1.76 km.Our system recovers targets contributing as little as 0.00016%of the total detected signal,enhancing a standard camera’s signal recovery capacity by nearly 200×.To validate our approach,we introduce the first-ever real-world multiperspective scattering dataset,providing a critical benchmark for future research.We mark a paradigm shift in passive imaging,offering transformative potential for real-world applications under extreme atmospheric scattering conditions.展开更多
In this paper, the problem of pre-specified performance fault-tolerant cluster consensus control and fault direction identification is solved for the human-in-the-loop(HIL) swarm unmanned aerial vehicles(UAVs) in the ...In this paper, the problem of pre-specified performance fault-tolerant cluster consensus control and fault direction identification is solved for the human-in-the-loop(HIL) swarm unmanned aerial vehicles(UAVs) in the presence of possible nonidentical and unknown direction faults(NUDFs) in the yaw channel.The control strategy begins with the design of a pre-specified performance event-triggered observer for each individual UAV.These observers estimate the outputs of the human controlled UAVs, and simultaneously achieve the distributed design of actual control signals as well as cluster consensus of the observer output.It is worth mentioning that these observers require neither the high-order derivatives of the human controlled UAVs' output nor a priori knowledge of the initial conditions. The fault-tolerant controller realizes the pre-specified performance output regulation through error transformation and the Nussbaum function. It should be pointed out that there are no chattering caused by the jump of the Nussbaum function when a reverse fault occurs. In addition, to provide a basis for further solving the problem of physical malfunctions, a fault direction identification algorithm is proposed to accurately identify whether a reverse fault has occurred. Simulation results verify the effectiveness of the proposed control and fault direction identification strategies when the reverse faults occur.展开更多
In order to gain a deeper understanding of the effect of pulsed current on the mechanical properties and size effect of nanocrystalline Ni foils,nanocrystalline Ni foils with different grain thickness-to-grain size ra...In order to gain a deeper understanding of the effect of pulsed current on the mechanical properties and size effect of nanocrystalline Ni foils,nanocrystalline Ni foils with different grain thickness-to-grain size ratios(λ)were prepared using pulsed electrodeposition in this paper and unidirectional tensile experiments were carried out at room temperature with different currents and their applied directions.The experimental results show that the nanocrystalline Ni foil produces an obvious electroplasticity effect after applying the current field,and when 300<λ<1100,the current weakens the size effect of nanocrystalline Ni foils to a certain extent,and the angle between the current direction and the deformation direction also affects the mechanical response of nanocrystalline Ni foils,and when the angle between the current direction and the deformation direction is 0°,electroplasticity effect is the best,and the current has the most significant effect of abating the size effect of the material.The mechanism of unidirectional tensile deformation of nanocrystalline Ni foils under the effect of pulsed current was analyzed using TEM and TKD.It was found that the applied pulse current increased the activity of the nanocrystalline boundaries,promoted the movement of dislocations,and reduced the tendency of dislocation entanglement.The higher the peak current density and the smaller the angle between the direction of the current and the direction of deformation,the smaller the grain boundary orientation difference,the more dispersed the grain orientation,and the lower the density of geometrically necessary dislocations(GND)in the deformed nanocrystalline foil,the more significant the effect on material plasticity improvement.展开更多
Surface recrystallization(RX) is a typical grain defect observed in directionally solidified(DS) Ni-based superalloys. Most studies have focused on the RX behavior and its impact on the mechanical properties of single...Surface recrystallization(RX) is a typical grain defect observed in directionally solidified(DS) Ni-based superalloys. Most studies have focused on the RX behavior and its impact on the mechanical properties of single-crystal(SC) superalloys, with limited research on its influence on the high-temperature mechanical properties of DS superalloys. This study systematically investigated the effect of RX on the high-temperature tensile properties of a DS DZ409 superalloy. The results show that at 650℃, the yield strength decreases almost linearly with an increase in RX fraction. A significant reduction in elongation is observed as the RX fraction increases from 0% to 4.9%. However, beyond this point, further increase in RX fraction leads to minimal changes in elongation. At 950℃, both yield strength and elongation decrease as the RX fraction increases from 0% to 4.9%. At 650℃, fractures in the RX DS superalloys exhibit a mixed mode of transgranular and intergranular cleavage fracture, while at 950℃, it features a combination of ductile and intergranular dimple fractures. The failure mechanism of the RX DS superalloy is associated with the introduction of transverse grain boundaries(GBs) during RX. In the early stages of tensile testing at intermediate and high temperatures, cracks can easily initiate at these GBs. Subsequently, the cracks propagate along the GBs into the DS matrix, ultimately leading to failure of the DS superalloy.展开更多
We proposed a new technique route of directional solidification for the manufacture of super slab.A 7-t laboratory-scale thick slab was casted and characterised for trial.To further understand the process,the evolutio...We proposed a new technique route of directional solidification for the manufacture of super slab.A 7-t laboratory-scale thick slab was casted and characterised for trial.To further understand the process,the evolution of the multiple physical fields during the directional solidification was simulated and verified.Similar to the convectional ingot casting,a negative segregated cone of equiaxed grains was formed at the bottom,and a seriously positive segregated region was formed beneath the top surface of the slab.Specific measures on the lateral walls,base plate,and free surface were strongly recommended to ensure that the slab is relatively directionally casted.A water-cooling copper base plate accelerates the solidification rate and the columnar growth along the vertical direction.It inhibits the sedimentation of equiaxed grains and enlarges the columnar zone.Based on the simulation analysis,it can be concluded that the directional solidification technique route is promising to manufacture super slab with lower segregation level,and less porosities and inclusions.展开更多
文摘The efficiency and stability of catalysts for photocatalytic hydrogen evolution(PHE)are largely governed by the charge transfer behaviors across the heterojunction interfaces.In this study,CuO,a typical semiconductor featuring a broad spectral absorption range,is successfully employed as the electron acceptor to combine with CdS for constructing a S-scheme heterojunction.The optimized photocatalyst(CdSCuO2∶1)delivers an exceptional hydrogen evolution rate of 18.89 mmol/(g·h),4.15-fold higher compared with bare CdS.X-ray photoelectron spectroscopy(XPS)and ultraviolet-visible diffuse reflection absorption spectroscopy(UV-vis DRS)confirmed the S-scheme band structure of the composites.Moreover,the surface photovoltage(SPV)and electron paramagnetic resonance(EPR)indicated that the photogenerated electrons and photogenerated holes of CdS-CuO2∶1 were respectively transferred to the conduction band(CB)of CdS with a higher reduction potential and the valence band(VB)of CuO with a higher oxidation potential under illumination,as expected for the S-scheme mechanism.Density-functional-theory calculations of the electron density difference(EDD)disclose an interfacial electric field oriented from CdS to CuO.This built-in field suppresses charge recombination and accelerates carrier migration,rationalizing the markedly enhanced PHE activity.This study offers a novel strategy for designing S-scheme heterojunctions with high light harvesting and charge utilization toward sustainable solar-tohydrogen conversion.
基金financially supported by the National Natural Science Foundation of China(Nos.22475057 and No.52373262).
文摘Directional three-dimensional carbon-based foams are emerging as highly attractive candidates for promising electromagnetic wave absorbing materials(EWAMs)thanks to their unique architecture,but their construction usually involves complex procedures and extremely depends on unidirectional freezing technique.Herein,we propose a groundbreaking approach that leverages the assemblies of salting-out protein induced by ammonium metatungstate(AM)as the precursor,and then acquire directional three-dimensional carbon-based foams through simple pyrolysis.The electrostatic interaction between AM and protein ensures well dispersion of WC_(1−x)nanoparticles on carbon frameworks.The content of WC_(1−x)nanoparticles can be rationally regulated by AM dosage,and it also affects the electromagnetic(EM)properties of final carbon-based foams.The optimized foam exhibits exceptional EM absorption performance,achieving a remarkable minimum reflection loss of−72.0 dB and an effective absorption bandwidth of 6.3 GHz when EM wave propagates parallel to the directional pores.Such performance benefits from the synergistic effects of macroporous architecture and compositional design.Although there is a directional dependence of EM absorption,radar stealth simulation demonstrates that these foams can still promise considerable reduction in radar cross section with the change of incident angle.Moreover,COMSOL simulation further identifies their good performance in preventing EM interference among different electronic components.
基金supported by the National Natural Science Foundation of China(52074045,52274074)the Science Fund for Distinguished Young Scholars of Chongqing(CSTB2022NSCQ-JQX0028).
文摘Developing deep fragmented soft coalbed methane(CBM)can significantly enhance domestic natural gas supplies,reduce reliance on imported energy,and bolster national energy security.This manuscript provides a comprehensive review of commonly employed coalbed methane extraction technologies.It then delves into several critical issues in the current stage of CBM exploration and development in China,including the compatibility of existing technologies with CBM reservoirs,the characteristics and occurrence states of CBM reservoirs,critical desorption pressure,and gas generation mechanisms.Our research indicates that current CBM exploration and development technologies in China have reached an internationally advanced level,yet the industry is facing unprecedented challenges.Despite progress in low-permeability,high-value coal seams,significant breakthroughs have not been achieved in exploring other types of coal seams.For different coal reservoirs,integrated extraction technologies have been developed,such as surface pre-depressurisation and segmented hydraulic fracturing of coal seam roof strata.Additionally,techniques like large-scale volume fracturing in horizontal wells have been established,significantly enhancing reservoir stimulation effects and coalbed methane recovery rates.However,all of these technologies are fundamentally based on permeation.These technologies lack direct methods aimed at enhancing the diffusion rate of CBM,thereby failing to fully reflect the unique characteristics of CBM.Current CBM exploration and development theories and technologies are not universally applicable to all coal seams.They do not adequately account for the predominantly adsorbed state of CBM,and the complex and variable gas generation mechanisms further constrain CBM development in China.Finally,continuous exploration of new deep CBM exploration technologies is necessary.Integrating more effective reservoir stimulation technologies is essential to enhance technical adaptability concerning CBM reservoir characteristics,gas occurrence states,and gas generation mechanisms,ultimately achieving efficient CBM development.We conclude that while China possesses a substantial foundation of deep fractured CBM resources,industry development is constrained and requires continuous exploration of new CBM exploration and development technologies to utilize these resources effectively.
基金supported by the National Natural Science Foundation of China(Grant No.52404155)State Key Laboratory of Mining Disaster Prevention and Control(Shandong University of Science and Technology)+1 种基金Ministry of Education(Grant No.JMDPC202402)supported by the opening project of State Key Laboratory of Explosion Science and Safety Protection(Beijing Institute of Technology).The opening project number is KFJJ24-20M.
文摘Aiming at mitigating the high risks associated with conventional explosive blasting,this study developed a safe directional fracturing technique,i.e.instantaneous expansion with a single fracture(IESF),using a coal-based solid waste expanding agent.First,the mechanism of directional fracturing blasting by the IESF was analyzed,and the criterion of directional crack initiation was established.On this basis,laboratory experiments and numerical simulations were conducted to systematically evaluate the directional fracturing blasting performance of the IESF.The results indicate that the IESF presents an excellent directional fracturing effect,with average surface undulation differences ranging from 8.1 mm to 22.7 mm on the fracture surfaces.Moreover,during concrete fracturing tests,the stresses and strains in the fracturing direction are measured to be 2.16-3.71 times and 8 times larger than those in the nonfracturing direction,respectively.Finally,the IESF technique was implemented for no-pillar mining with gob-side entry retaining through roof cutting and pressure relief in an underground coal mine.The IESF technique effectively created directional cracks in the roof without causing severe roadway deformation,achieving an average cutting rate and maximum roadway deformation of 94%and 197 mm,respectively.These on-site test results verified its excellent directional rock fracturing performance.The IESF technique,which is safe,efficient,and green,has considerable application prospects in the field of rock mechanics and engineering.
基金supported by the National Natural Science Foundation of China (Grant Nos.52304227 and 52104133)Scientific and Technological Research Platform for Disaster Prevention and Control of Deep Coal Mining (Anhui University of Science and Technology) (Grant No.DPDCM2208).
文摘To investigate the effects of the maximum principal stress direction(θ)and cross-section shape on the failure characteristics of sandstone,true-triaxial compression experiments were conducted using cubic samples with rectangular,circular,and D-shaped holes.Asθincreases from 0°to 60°in the rectangular hole,the left failure location shifts from the left corner to the left sidewall,the left corner,and then the floor,while the right failure location shifts from the right corner to the right sidewall,right roof corner,and then the roof.Furthermore,the initial failure vertical stress first decreases and then increases.In comparison,the failure severity in the rectangular hole decreases for variousθvalues as 30°>45°>60°>0°.With increasingθ,the fractal dimension(D)of rock slices first increases and then decreases.For the rectangular and D-shaped holes,whenθ=0°,30°,and 90°,D for the rectangular hole is less than that of the D-shaped hole.Whenθ=45°and 60°,D for the rectangular hole is greater than that of the D-shaped hole.Theoretical analysis indicates that the stress concentration at the rectangular and D-shaped corners is greater than the other areas.The failure location rotates with the rotation ofθ,and the failure occurs on the side with a high concentration of compressive stress,while the side with the tensile and compressive stresses remains relatively stable.Therefore,the fundamental reason for the rotation of failure location is the rotation of stress concentration,and the external influencing factor is the rotation ofθ.
基金Project(52204164) supported by the National Natural Science Foundation of ChinaProject(2023ZKPYSB01) supported by the Fundamental Research Funds for the Central Universities,China。
文摘To enhance the recuperation rate of the mine and comply with the stipulations of green mining technology, it is vital to expeditiously recuperate the coal pillar resources in the final stage, thus preventing the considerable squandering of resources. The coal pillar resource of the main roadway and its branch roadway constitutes a significant recovery subject. Its coal pillar shape is regular and possesses a considerable strike distance, facilitating the arrangement of the coal pillar recovery working face (CPRWF) for mining operations. However, for the remaining coal pillars with a thick and hard roof (THF) and multiple tectonic zones, CPRWF encounters challenges in selecting an appropriate layout, managing excessive roof pressure, and predicting mining stress. Aiming at the roadway coal pillar group with THF and multi-structural areas in specific projects, a method of constructing multi-stage CPRWF by one side gob-side entry driving (GSED) and one side roadway reusing is proposed. Through theoretical calculation of roof fracture and numerical simulation verification, combined with field engineering experience and economic analysis, the width of the narrow coal pillar (NCP) in the GSED is determined to be 10 m and the length of the CPRWF is 65 m. Concurrently, the potential safety hazard that the roof will fall asymmetrically and THF is difficult to break during CPRWF mining after GSED is analyzed and verified. Then, a control method involving the pre-cutting of the roof in the reused roadway before mining is proposed. This method has been shown to facilitate the complete collapse of THF, reduce the degree of mine pressure, and facilitate the symmetrical breaking of the roof. Accordingly, a roof-cutting scheme based on a directional drilling rig, bidirectional shaped polyvinyl chloride (PVC) pipe, and emulsion explosive was devised, and the pre-splitting of 8.2 m THF was accomplished. Field observations indicate that directional cracks are evident in the roof, the coal wall is flat during CPRWF mining, and the overall level of mining pressure is within the control range. Therefore, the combined application of GSED and roof-cutting technology for coal pillar recovery has been successfully implemented, thereby providing new insights and engineering references for the construction and pressure relief mining of CPRWF.
基金supported by the Key R&D Program of Zhejiang Province(Nos.2023C01166 and 2024SJCZX0046)the Zhejiang Provincial Natural Science Foundation of China(Nos.LDT23E05013E05 and LD24E050009)the Natural Science Foundation of Ningbo(No.2021J150),China.
文摘Accuracy allocation is crucial in the accuracy design of machining tools.Current accuracy allocation methods primarily focus on positional deviation,with little consideration for tool direction deviation.To address this issue,we propose a geometric error cost sensitivity-based accuracy allocation method for five-axis machine tools.A geometric error model consisting of 4l error components is constructed based on homogeneous transformation matrices.Volumetric points with positional and tool direction deviations are randomly sampled to evaluate the accuracy of the machine tool.The sensitivity of each error component at these sampling points is analyzed using the Sobol method.To balance the needs of geometric precision and manufacturing cost,a geometric error cost sensitivity function is developed to estimate the required cost.By allocating error components affecting tool direction deviation first and the remaining components second,this allocation scheme ensures that both deviations meet the requirements.We also perform numerical simulation of a BC-type(B-axis and C-axis type)five-axis machine tool to validate the method.The results show that the new allocation scheme reduces the total geometric error cost by 27.8%compared to a uniform allocation scheme,and yields the same positional and tool direction machining accuracies.
文摘Professor Paul Crosthwaite,from the School of Literature,Languages,and Cultures at the University of Edinburgh,is a prominent scholar in the interdisciplinary field of literature and economics.He is a co-editor of the Palgrave Studies in Literature,Culture,and Economics series and The Cambridge Companion to Literature and Economics(2022).In recent years,he has significantly influenced the intersection of literature and economics,advocating particularly for a shift towards the Economic Humanities.This interview covers:1.The definition and theoretical origin of the Economic Humanities;2.The internal heterogeneity and critical limitations of the New Economic Criticism,and the theoretical advantages and potential development of the Economic Humanities;3.What research paradigms do Environmental Humanities,Medical Humanities,and Digital Humanities provide for the Economic Humanities;4.How literary researchers can work at the interface of the Economic Humanities research.As a novel interdisciplinary interface between literature and economics,Professor Paul Crosthwaite’s concept of the Economic Humanities not only pioneers methodological tools for interdisciplinary studies of literature and economics but also underscores the interpretative potential and disciplinary benefits of literary viewpoints on economics.This underscores the vital role of literature in human knowledge,meriting attention from the literary research academia.
文摘According to the measurement principle of the traditional interferometer,a narrowband signal model is established and used,however,for wideband signals or multiple signals,this model is invalid.For the problems of direction finding with interferometer for wideband signals and multiple signals scene,a frequency domain phase interferometer is proposed and the concrete implementation scheme is given.The proposed method computes the phase difference in frequency domain,and finds multi-target results with judging the spectrum amplitude changing,and uses the frequency phase difference to compute the arrival angle.Theoretical analysis and simulation results show that the proposed method effectively solves the problem of the angle estimation with phase interferometer for wideband signals,and has good performance in multiple signals scene with nonoverlapping spectrum or partially overlapping.In addition,the wider the signal bandwidth,the better direction finding performance of this algorithm.
基金the National Natural Science Foundation of China(Grant No.12171294)。
文摘Interval-valued pre-aggregation functions are a hot topic in the research of aggregation functions and have received considerable attention in recent years.As a special class of interval-valued pre-aggregation functions,(light)interval-valued pre-t-norms were initially proposed by Wang and Hu,but their properties were not further discussed by the authors.The main purpose of this paper is to study in depth the properties and generation of(light)intervalvalued pre-t-norms.Firstly,several properties of(light)interval-valued pre-t-norms and their relationship with(light)pre-t-norms are presented.Then,two different generation methods for(light)interval-valued pre-t-norms are introduced.Finally,it demonstrates a specific application of(light)interval-valued pre-t-norms in constructing interval-valued directional monotonic fuzzy implications,namely,using the(light)interval-valued pre-t-norm IT,interval-valued fuzzy negations IN,and(light)interval-valued pre-t-conorm IS to construct interval-valued QL-directional monotonic operations.
基金supported by the National Key Research and Development Program of China(Grant No.2019YFA0705300)the National Natural Science Foundation of China(Grant No.51974057)the Fundamental Research Funds for the Central Universities。
文摘Columnar grains offer considerable advantages in terms of microstructure for resisting high-temperature low-cycle fatigue. In additive manufacturing, the formation of fine columnar grains is common. However, post-heat treatment often transforms these grains into equiaxed grains. This study aimed to tailor the grain morphology by controlling the precipitation of carbides. By balancing the restraining effects of carbide pinning and grain growth, we achieved carbide-assisted in situ-directional recrystallization. This process preserved the columnar grains created via laser powder bed fusion, even after high-temperature heat treatment. The approach emphasizes promoting the longitudinal growth of columnar grains while preventing their broadening. Additionally, we characterized the evolution of carbides and γ′ precipitates and examined their role in nucleation and growth during recrystallization. This study supports the viability of carbide-assisted in situ-directional recrystallization in additive manufacturing alloys, introducing an innovative strategy for microstructure customization. The implementation of carbon stabilization (CS) treatment to control the carbide distribution led to a 40 % improvement in the creep life at 900 ℃ and 150 MPa.
文摘Mental healthcare in Ethiopia is underutilized due to a lack of resources and skilled practitioners.Psychological counselling offers unique intervention possibilities because of its focus on a wide range of mental health and social justice issues.This literature review tracks the historical development of the profession of psychological counselling in Ethiopia to establish what has been achieved to date and the development challenges.Key achievements include recognition of the profession by the Ministry of Education,growing public awareness,and increasing capacity of practitioners skilled in psychological counselling.Challenges include limited contextually relevant training,poor representation of the profession within Ministry of Health policies,poor public and government mental health literacy,and a lack of regulatory frameworks.Postgraduate training would benefit from more culturally,contextually,and linguistically appropriate evidence-based,indigenous psychology practices.The profession would benefit from engagement in government policy development that promotes mental health,and professional regulatory bodies to hold practitioners accountable to professional standards and ethical practice.
基金Supported by the Key Laboratory Fund for Equipment Pre-Research(6142207210202)。
文摘Aiming at the problem that infrared small target detection faces low contrast between the background and the target and insufficient noise suppression ability under the complex cloud background,an infrared small target detection method based on the tensor nuclear norm and direction residual weighting was proposed.Based on converting the infrared image into an infrared patch tensor model,from the perspective of the low-rank nature of the background tensor,and taking advantage of the difference in contrast between the background and the target in different directions,we designed a double-neighborhood local contrast based on direction residual weighting method(DNLCDRW)combined with the partial sum of tensor nuclear norm(PSTNN)to achieve effective background suppression and recovery of infrared small targets.Experiments show that the algorithm is effective in suppressing the background and improving the detection ability of the target.
基金financially supported by the National Natural Science Foundation of China(Grant No.51875211)the Beijing Natural Science Foundation(Grant No.L223001)。
文摘Microporosity formed in the solidification process of Al alloys is detrimental to the alloy properties.A two-dimensional cellular automaton(CA)model was developed to simulate the microstructure and microporosity formation in Al-Cu alloys,considering variations in Cu content and solidification rate.The results indicate that the Cu content primarily influences the growth of microporosity.To validate the model,directional solidification experiments were conducted on Al-Cu alloys with varing Cu contents and withdrawal rates.The experimental results of dendrites and microporosity characteristics agree well with the predictions from the developed model,thus confirming the validity of the model.The alloy’s liquidus temperature,dendrite morphology,and hydrogen saturation solubility arising from different Cu contents have significant effects on microporosity morphology.The withdrawal rate primarily affects the nucleation of hydrogen microporosity by altering cooling rates and dendritic growth rates,resulting in different microporosity characteristics.
基金support from Liaoning Revitalization Talents Program(XLYC2203068)National Natural Science Foundation of China(21902116)2024 Fundamental Research Funding of the Educational Department of Liaoning Province.Y.L.acknowledges the Program of China Scholarships Council(No.202206250016).
文摘Direct propane dehydrogenation(DPDH)represents a highly attractive route for on-purpose propylene production,a key building block in the petrochemical industry.In particular,among various catalytic platforms,vanadium-based catalysts have emerged as promising candidates due to their tunable properties including redox ability,surface acidity,and resistance to coking.Although the catalytic community has obtained great achievement in this area,how to promote vanadium-based catalysts towards the next step in DPDH applications like industrial-level implementations is still challenging.Moreover,there are still several controversial theories in our community,meaning it is necessary to clarify these indistinct points to pave the way for the next generation of research.Herein,the pivotal modification strategies of vanadium-based catalysts have been summarized via introducing representative works.In addition,the current unclear mechanism and research gaps,especially in the issues of deactivation and selectivity control,are also revealed so that the potential research directions are well-founded proposed.By integrating fundamental understanding and practical considerations,this review aims to inspire the further development of vanadium-based DPDH catalysts for in-depth academic research and next-generation industrial deployment.
基金supported by the Shenzhen Science and Technology Project,China(Grant No.KCXFZ20240903094301003).
文摘Passive imaging through intense atmospheric scattering is a critical yet formidable challenge in optical imaging,with profound implications across various applications.Conventional cameras struggle under severe scattering conditions,fundamentally limiting their effectiveness.We propose a groundbreaking directional atmospheric scattering model that revolutionizes passive imaging capabilities,converting a conventional camera to a super-camera.The model precisely characterizes directional photon propagation through scattering media,transforming this historically ill-posed problem into a well-posed solution,based on which a 4D spatial-angular scattering reconstruction method is proposed,which leverages both ballistic photons and directionally resolved scattered light,without relying on any scene-specific priors,to achieve unprecedented passive imaging performance enabling color imaging through over 12 transport mean free paths at distances up to 1.76 km.Our system recovers targets contributing as little as 0.00016%of the total detected signal,enhancing a standard camera’s signal recovery capacity by nearly 200×.To validate our approach,we introduce the first-ever real-world multiperspective scattering dataset,providing a critical benchmark for future research.We mark a paradigm shift in passive imaging,offering transformative potential for real-world applications under extreme atmospheric scattering conditions.
基金supported in part by the National Natural Science Foundation of China(62173028,62233015,62173024)the Guangdong Basic and Applied Basic Research Foundation(2024A1515011493)+3 种基金the Science,Technology&Innovation Project of Xiongan New Area(2023XAGG0062)Beijing Natural Science Foundation(4232060)the International Scientists Project,Beijing Natural Science Foundation(IS23065)the Brazilian Research Council(303289/2022-8)
文摘In this paper, the problem of pre-specified performance fault-tolerant cluster consensus control and fault direction identification is solved for the human-in-the-loop(HIL) swarm unmanned aerial vehicles(UAVs) in the presence of possible nonidentical and unknown direction faults(NUDFs) in the yaw channel.The control strategy begins with the design of a pre-specified performance event-triggered observer for each individual UAV.These observers estimate the outputs of the human controlled UAVs, and simultaneously achieve the distributed design of actual control signals as well as cluster consensus of the observer output.It is worth mentioning that these observers require neither the high-order derivatives of the human controlled UAVs' output nor a priori knowledge of the initial conditions. The fault-tolerant controller realizes the pre-specified performance output regulation through error transformation and the Nussbaum function. It should be pointed out that there are no chattering caused by the jump of the Nussbaum function when a reverse fault occurs. In addition, to provide a basis for further solving the problem of physical malfunctions, a fault direction identification algorithm is proposed to accurately identify whether a reverse fault has occurred. Simulation results verify the effectiveness of the proposed control and fault direction identification strategies when the reverse faults occur.
基金Project(51975167)supported by the National Natural Science Foundation of China。
文摘In order to gain a deeper understanding of the effect of pulsed current on the mechanical properties and size effect of nanocrystalline Ni foils,nanocrystalline Ni foils with different grain thickness-to-grain size ratios(λ)were prepared using pulsed electrodeposition in this paper and unidirectional tensile experiments were carried out at room temperature with different currents and their applied directions.The experimental results show that the nanocrystalline Ni foil produces an obvious electroplasticity effect after applying the current field,and when 300<λ<1100,the current weakens the size effect of nanocrystalline Ni foils to a certain extent,and the angle between the current direction and the deformation direction also affects the mechanical response of nanocrystalline Ni foils,and when the angle between the current direction and the deformation direction is 0°,electroplasticity effect is the best,and the current has the most significant effect of abating the size effect of the material.The mechanism of unidirectional tensile deformation of nanocrystalline Ni foils under the effect of pulsed current was analyzed using TEM and TKD.It was found that the applied pulse current increased the activity of the nanocrystalline boundaries,promoted the movement of dislocations,and reduced the tendency of dislocation entanglement.The higher the peak current density and the smaller the angle between the direction of the current and the direction of deformation,the smaller the grain boundary orientation difference,the more dispersed the grain orientation,and the lower the density of geometrically necessary dislocations(GND)in the deformed nanocrystalline foil,the more significant the effect on material plasticity improvement.
基金supported by the National Science and Technology Major Project(No.HT-J2019-VI-0020-0136)the National Youth Talent Support Program,and the Fundamental Research Funds for the Central Universities(No.xtr072024004).
文摘Surface recrystallization(RX) is a typical grain defect observed in directionally solidified(DS) Ni-based superalloys. Most studies have focused on the RX behavior and its impact on the mechanical properties of single-crystal(SC) superalloys, with limited research on its influence on the high-temperature mechanical properties of DS superalloys. This study systematically investigated the effect of RX on the high-temperature tensile properties of a DS DZ409 superalloy. The results show that at 650℃, the yield strength decreases almost linearly with an increase in RX fraction. A significant reduction in elongation is observed as the RX fraction increases from 0% to 4.9%. However, beyond this point, further increase in RX fraction leads to minimal changes in elongation. At 950℃, both yield strength and elongation decrease as the RX fraction increases from 0% to 4.9%. At 650℃, fractures in the RX DS superalloys exhibit a mixed mode of transgranular and intergranular cleavage fracture, while at 950℃, it features a combination of ductile and intergranular dimple fractures. The failure mechanism of the RX DS superalloy is associated with the introduction of transverse grain boundaries(GBs) during RX. In the early stages of tensile testing at intermediate and high temperatures, cracks can easily initiate at these GBs. Subsequently, the cracks propagate along the GBs into the DS matrix, ultimately leading to failure of the DS superalloy.
基金the National Natural Science Foundation of China(No.52074182)Joint Funds of the National Natural Science Foundation of China(No.U23A20612).
文摘We proposed a new technique route of directional solidification for the manufacture of super slab.A 7-t laboratory-scale thick slab was casted and characterised for trial.To further understand the process,the evolution of the multiple physical fields during the directional solidification was simulated and verified.Similar to the convectional ingot casting,a negative segregated cone of equiaxed grains was formed at the bottom,and a seriously positive segregated region was formed beneath the top surface of the slab.Specific measures on the lateral walls,base plate,and free surface were strongly recommended to ensure that the slab is relatively directionally casted.A water-cooling copper base plate accelerates the solidification rate and the columnar growth along the vertical direction.It inhibits the sedimentation of equiaxed grains and enlarges the columnar zone.Based on the simulation analysis,it can be concluded that the directional solidification technique route is promising to manufacture super slab with lower segregation level,and less porosities and inclusions.
