This study presents a reflective bibliometric review of 1457 peer-reviewed articles published in the Journal of Psychology in Africa(2008-2024,17 years),using a Meta-Editorial Mapping Framework(MEMF)analysis.The MEMF ...This study presents a reflective bibliometric review of 1457 peer-reviewed articles published in the Journal of Psychology in Africa(2008-2024,17 years),using a Meta-Editorial Mapping Framework(MEMF)analysis.The MEMF integrates citation metrics,keyword novelty ratios,TF-IDF weighting,and cluster-based topic modeling to trace long-term thematic trends and editorial evolution.Findings reveal sustained attention to foundational domains such as mental health,education,and identity,alongside a gradual integration of emergent themes including digital well-being,organizational behavior,and post-pandemic adaptation.Articles with moderate topical novelty(40%-60% new keywords)achieved the highest citation and usage metrics,suggesting that integrative innovation enhances scholarly impact.Clustering analyses indicate that the journal’s content forms overlapping conceptual domains rather than isolated silos.These insights contribute to editorial strategy,authorial positioning,and the future design of regional academic platforms.Moreover,the findings provide evidence supporting the use of the MEMF as a replicable tool for meta-editorial analysis across disciplinary and geographic boundaries.展开更多
Map building by multi-robot is very important to accomplish autonomous navigation,and one of the basic problems and research hotspots is how to merge the maps into a single one in the field of multi-robot map building...Map building by multi-robot is very important to accomplish autonomous navigation,and one of the basic problems and research hotspots is how to merge the maps into a single one in the field of multi-robot map building.A novel approach is put forward based on adaptive differential evolution to map building for the multi-robot system.The multi-robot mapping-building system adopts the methods of decentralized exploration and concentrated mapping.The adaptive differential evolution algorithm is used to search in the space of possible transformation,and the iterative search is performed with the goal of maximizing overlapping regions.The map is translated and rotated so that the two maps can be overlapped and merged into a single global one successfully.This approach for map building can be realized without any knowledge of their relative positions.Experimental results show that the approach is effective and feasibile.展开更多
With the urgent need to resolve complex behaviors in nonlinear evolution equations,this study makes a contribution by establishing the local existence of solutions for Cauchy problems associated with equations of mixe...With the urgent need to resolve complex behaviors in nonlinear evolution equations,this study makes a contribution by establishing the local existence of solutions for Cauchy problems associated with equations of mixed types.Our primary contribution is the establishment of solution existence,illuminating the dynamics of these complex equations.To tackle this challenging problem,we construct an approximate solution sequence and apply the contraction mapping principle to rigorously prove local solution existence.Our results significantly advance the understanding of nonlinear evolution equations of mixed types.Furthermore,they provide a versatile,powerful approach for tackling analogous challenges across physics,engineering,and applied mathematics,making this work a valuable reference for researchers in these fields.展开更多
The hot deformation behavior of GH3230 superalloy under selected deformation conditions ranging from 950 to 1150℃with strain rates ranging from 0.01 to 10 s^(–1)was studied through isothermal hot compression experim...The hot deformation behavior of GH3230 superalloy under selected deformation conditions ranging from 950 to 1150℃with strain rates ranging from 0.01 to 10 s^(–1)was studied through isothermal hot compression experiments.Based on the obtained flow stresses,a strain-compensated Arrhenius-type model was developed for the description of hot deformation behavior,and the consistency of the predicted flow stresses with the experimental values confirms the accuracy of the developed model.Furthermore,the processing maps were constructed and classified into the instability domain,low-dissipation stability domain and high-dissipation stability domain in accordance with the dynamic material model and the instability criterion.Microstructure observations indicated that the instability domain exhibits the adiabatic shear bands formation,and the low-power dissipation domain exhibits partial dynamic recrystallization(DRX),with the temperature increase/strain rate decrease being favorable for the DRX.The high-dissipation stability domain was occupied by uniformly fine equiaxed grains,and was identified as the optimal processing window,which corresponds to the deformation conditions at 1070–1150℃ with strain rates ranging from 0.01 to 0.15 s^(–1).Moreover,various DRX mechanisms are observed to occur during the hot deformation,which include the discontinuous dynamic recrystallization,characterized by nucleation at bulged boundaries,the continuous dynamic recrystallization with subgrain progressive rotation and the particle stimulated nucleation mechanism with stimulated nucleation of carbide particles.展开更多
The Eastern Kunlun Orogenic Belt(EKOB)in the Northern Tibet Plateau hosts a wide variety of metal deposits related to the Late Paleozoic to Mesozoic magmatism.In this study,we investigate the spatiotemporal distributi...The Eastern Kunlun Orogenic Belt(EKOB)in the Northern Tibet Plateau hosts a wide variety of metal deposits related to the Late Paleozoic to Mesozoic magmatism.In this study,we investigate the spatiotemporal distribution of the Late Paleozoic to Mesozoic granitic rocks and associated metal deposits in the EKOB and provide a comprehensive compilation of the geochronological,geochemical and isotopic data on these rocks.We compute regional zircon Hf isotope and crustal thickness maps from the data,based on which a comprehensive model is proposed involving subduction(ca.270–240 Ma),continental collision(ca.240–224 Ma),and post-collisional extension(ca.224–200 Ma)for the Late Paleozoic to Mesozoic Paleo-Tethys evolution in the EKOB.Zircon Hf isotopic and crustal thickness mapping of Late Paleozoic to Mesozoic magmatic rocks was carried out to evaluate their spatio-temporal and genetic links with the regional metallogeny.The polymetallic Fe-skarn and porphyry Cu(Mo)deposits in the EKOB are located above the Moho uplift region,featuring a comparatively thin crust.Granites associated with porphyry Cu(Mo)and polymetallic Fe skarn mineralization are commonly characterized by highε_(Hf)(t)and younger T_(DM)cvalues,whereas granite related to Cu-Mo-Sn skarn deposits exhibit more variableε_(Hf)(t)values,T_(DM)c ages,and the crust thickness,which suggest that more crustal materials contributed to the formation of Cu-Mo-Sn skarn deposits than those for porphyry Cu(Mo)and polymetallic Fe skarn mineralization.In contrast,vein-type Au deposits are located primarily where the Moho surface displays a depression,i.e.,where the continental crust is relatively thick.The magmatic rocks associated with Au mineralization are characterized by lowε_(Hf)(t)and high T_(DM)cvalues,representing reworked ancient crustal components,similar to those associated with porphyry Mo and epithermal Ag-Pb-Zn-(Au)deposits.Our study indicates that the emplacement of magmatic-hydrothermal deposits was controlled by the crustal structure and magma sources.展开更多
Defect existing form and its evolution play an important role in the thermoelectric transport process. Here different forms of Pb into the Sn Se system were introduced in order to improve the thermoelectric and mechan...Defect existing form and its evolution play an important role in the thermoelectric transport process. Here different forms of Pb into the Sn Se system were introduced in order to improve the thermoelectric and mechanical properties of Sn Se. Pb/Sn Se samples were fabricated by vacuum melting, solid phase diffusion,spark plasma sintering and annealing treatment. The element valence mapping diagram and the X-ray photoelectron spectra(XPS) characteristic peaks of Pb show that a certain amount of elemental Pb exists in the initial state, and evolves into Pb^(2+)ion after annealing treatment. The micro-structure evolution leads to significant enhancement of the power factor and the ZT value. The power factor(PF) and the ZT value for Pb/Sn Se increases to 623 μW/m/K^(2) and 1.12 at 773 K after annealing treatment, respectively.Compared with Sn Se matrix, the hardness and fracture toughness of Pb/Sn Se samples increased by about40% and 10%, respectively. Reasonable control of microstructure evolution is expected to be a design idea to improve thermoelectric and mechanical properties of Sn Se.展开更多
In this paper we introduce the evolution law of thinking-neural network attractor in the field of thinking dynamics,a new idea about the attractor evolution using evolutional mapping transformation is given on the ba...In this paper we introduce the evolution law of thinking-neural network attractor in the field of thinking dynamics,a new idea about the attractor evolution using evolutional mapping transformation is given on the bases of generalized isologous concept. The idea is connected with the intuitive thinking.This paper lays a foundation for the further studying of the brain thinking process.展开更多
As a revolutionary industrial technology,additive manufacturing creates objects by adding materials layer by layer and hence can fabricate customized components with an unprecedented degree of freedom.For metallic mat...As a revolutionary industrial technology,additive manufacturing creates objects by adding materials layer by layer and hence can fabricate customized components with an unprecedented degree of freedom.For metallic materials,unique hierarchical microstructures are constructed during additive manufacturing,which endow them with numerous excellent properties.To take full advantage of additive manufacturing,an in-depth understanding of the microstructure evolution mechanism is required.To this end,this review explores the fundamental procedures of additive manufacturing,that is,the formation and binding of melt pools.A comprehensive processing map is proposed that integrates melt pool energy-and geometry-related process parameters together.Based on it,additively manufactured microstructures are developed during and after the solidification of constituent melt pool.The solidification structures are composed of primary columnar grains and fine secondary phases that form along the grain boundaries.The post-solidification structures include submicron scale dislocation cells stemming from internal residual stress and nanoscale precipitates induced by intrinsic heat treatment during cyclic heating of adjacent melt pool.Based on solidification and dislocation theories,the formation mechanisms of the multistage microstructures are thoroughly analyzed,and accordingly,multistage control methods are proposed.In addition,the underlying atomic scale structural features are briefly discussed.Furthermore,microstructure design for additive manufacturing through adjustment of process parameters and alloy composition is addressed to fulfill the great potential of the technique.This review not only builds a solid microstructural framework for metallic materials produced by additive manufacturing but also provides a promising guideline to adjust their mechanical properties.展开更多
High strength β titanium alloys are widely used in large load bearing components in the aerospace field. At present, large parts are generally formed by die forging. Different initial microstructures and deformation ...High strength β titanium alloys are widely used in large load bearing components in the aerospace field. At present, large parts are generally formed by die forging. Different initial microstructures and deformation process parameters will significantly affect the flow behavior. To precisely control the microstructures, researchers have conducted many studies to analyze the microstructure evolution law and deformation mechanism during hot compression. This review focuses on the microstructure evolution of high strength β titanium alloys during hot deformation, including dynamic recrystallization and dynamic recovery in the single-phase region and the dynamic evolution of the α phase in the two-phase region. Furthermore, the optimal hot processing regions, instability regions,and the relationship between the efficiency of power dissipation and the deformation mechanism in the hot processing map are summarized. Finally, the problems and development direction of using hot processing maps to optimize process parameters are also emphasized.展开更多
The hot deformation behavior of Al-Cu-Li alloy was investigated by hot compression tests in the temperature range of 340-500℃ with strain rate of 0.001-10.000 s^(-1).Based on the dynamic materials model(DMM),processi...The hot deformation behavior of Al-Cu-Li alloy was investigated by hot compression tests in the temperature range of 340-500℃ with strain rate of 0.001-10.000 s^(-1).Based on the dynamic materials model(DMM),processing maps of the test alloy were developed for optimizing hot processing parameters.The optimum parameters of hot deformation for Al-Cu-Li alloy are at temperature of 400-430℃and strain rate of about 0.100 s^(-1),with efficiency of power dissipation of around 30%.The microstructural manifestation of the alloy deformed in instability domains is flow localization,and dynamic softening first occurs in flow localizations structure.In stable domains,dynamic recovery(DRV) and dynamic recrystallization(DRX) are the main microstructural evolution mechanism.DRX is gradually strengthened with the increase in deformation temperature and the decrease in strain rate.During hot deformation,the DRX mechanism of Al-Cu-Li alloy is dominated by continuous DRX(CDRX).A DRX model of Al-Cu-Li alloy is proposed based on the microstructural evolution process of the test alloy.展开更多
Using historical topographic maps and aerospace remote sensing data since the 1930s,this study investigates the spatial and temporal evolution of Dongting Lake beach.The evolution characteristics of the beaches in dif...Using historical topographic maps and aerospace remote sensing data since the 1930s,this study investigates the spatial and temporal evolution of Dongting Lake beach.The evolution characteristics of the beaches in different regions and the related formation mechanism were also analyzed.The results show that Dongting Lake beach expanded from 1622.17 km^(2)in 1938 to 1962.28 km^(2)in 2018.With the addition of 980.96 km^(2)of reclaimed high bay beach,the beach area increased by 1321.07km^(2).However,the change process fluctuated somewhat rather than continuously increased.Substantial expansion of the beach area occurred during 1938-1948 and 1958-1998,while slow contraction of the beach area occurred during 1948-1958 and 1998-2018.Dongting Lake beach was dominated by terrigenous debris,the sedimentary types included lacustrine deposits,river alluvial deposits,floodplain and main channel deposits,and river-lake interaction deposits.The rapid expansion occurred in the estuary delta of the east branch of the Ouchi River,which advanced 38.55 km from the estuary toward the lake over the past 90 years.The causes of the changes in the beach included beach reclamation,sediment changes,and lake sand mining.Seventy embankments(covering 2057.77 km^(2))have been enclosed in the Dongting Lake area since 1930s,of which the high bay beach covered an area of 980.96km^(2).The amount of sediment deposited in Dongting Lake has reached 230857×10^(4) m^(3) since 1950s,which is equivalent to an average deposition height of 0.85 m on the lake's bottom.The mining of lake sand caused the beach to shrink,and the proportion of the beach area decreased from 77.18%in 1998 to 72.60%in 2018.The results of this study provide objective data for protecting the lakeshore's ecosystem and biodiversity and supporting the ecological restoration and environmental protection of the Yangtze River Basin.展开更多
By means of isothermal compression at temperatures in the range of 650-900℃and strain rates in the range of 0.001-1 s^(-1),the dynamic recrystallization behavior and microstructural evolution of a Cu-3.28 Ni-0.6 Si-0...By means of isothermal compression at temperatures in the range of 650-900℃and strain rates in the range of 0.001-1 s^(-1),the dynamic recrystallization behavior and microstructural evolution of a Cu-3.28 Ni-0.6 Si-0.22 Zn-0.11 Cr-0.04 P(wt%)alloy designed by a machine learning method were investigated.A semiempirical constitutive equation,processing maps and an average activation energy were generated.The microstructure under different conditions and the effect of strain rate on the texture of the alloy at 800-900℃were observed.The results show that the suitable temperature is800-900℃;when the strain is less than 0.4,the appropriate strain rate is 0.01-0.5 s^(-1);and when the strain is greater than 0.4,the appropriate strain rate is below0.05 s^(-1).After deformation at 800℃,the main texture changed from{112}<111>of copper to a uniform distribution with the increase in strain rate,but the sample did not have obvious texture after deformation at 850 and900℃.The above results can provide a reference for the selection of process parameters.展开更多
The hot deformation behavior and microstructure evolution of an Fe–30Cr–2Mo ultra-pure super ferritic stainless steel were investigated at the temperature range of 950–1150℃ and strain rate varying from 0.01 to 10...The hot deformation behavior and microstructure evolution of an Fe–30Cr–2Mo ultra-pure super ferritic stainless steel were investigated at the temperature range of 950–1150℃ and strain rate varying from 0.01 to 10 s^(−1).A strain compensated constitutive equation based on the Arrhenius-type model was established to predict the flow stress.The hot processing map based on the dynamic materials model was achieved to identify the optimum processing parameters.In addition,the features of microstructure evolution combined with the processing map were systematically investigated.The experimental results revealed that the flow stress increased with decreasing deformation temperature or increasing strain rate.Dynamic recovery was confirmed to be the predominant softening mechanism.The values of flow stress predicted by the strain compensated constitutive equation agreed well with the experimental values.The extent of dynamic recrystallization and recrystallized grain size increased with increasing deformation temperature or decreasing strain rate,and the continuous dynamic recrystallization was attributed to be the predominant mechanism of recrystallization during hot deformation.The optimum hot working parameters were determined to be the deformation temperature of 1070–1150℃ and strain rate of 0.1–1 s^(−1) with a peak power dissipation efficiency of 42%.展开更多
Ancient marine carbonates experienced complex modifications,making it difficult to identify reservoir genesis and effective porosity before hydrocarbon migration.To solve these issues,we used element mapping and carbo...Ancient marine carbonates experienced complex modifications,making it difficult to identify reservoir genesis and effective porosity before hydrocarbon migration.To solve these issues,we used element mapping and carbonate mineral laser U-Pb radiometric dating techniques to study the diagenetic environments based on geochemistry and diagenesis-porosity evolution based on geochronology of the dolomite reservoir of the Sinian Qigebrak Formation,northwest Tarim Basin.Two major understandings were obtained as follows:(1)Supported by petrographic observations,the element mapping,stable isotopes,strontium isotope,and cathodoluminescence tests were performed on different phases of dolomite cements precipitated in vugs and dissolved fissures.The results show that the dolomite reservoirs of the Qigebrak Formation went through freshwater,marine,extremely shallow burial,burial and hydrothermal diagenetic environments after synsedimentary dolomitization;the reservoir spaces were mainly formed in the synsedimentary period(primary pores)and freshwater environment(supergene dissolution pores)before burial;whereas the marine,burial and hydrothermal environments caused the gradual filling of reservoir space by dolomite cements.(2)Based on the above understandings,each phase of dolomite cement precipitated in the reservoir space was dated by the U-Pb radiometric dating technique,and the diagenesis-porosity evolution curves constrained by geochronology were established.The loss of reservoir porosity mainly occurred in the early Caledonian,and during the peak period of hydrocarbon generation of Yuertusi Formation source rock,the reservoirs still maintained at a porosity of 6%?10%.The above understandings provide a certain basis for the evaluation of accumulation effectiveness of the Sinian Qigebrak Formation,northwestern Tarim Basin,and provide a case for the application of mapping and dating techniques in the study of ancient carbonate reservoirs.展开更多
This article deals with a new fractional nonlinear delay evolution system driven by a hemi-variational inequality in a Banach space.Utilizing the KKM theorem,a result concerned with the upper semicontinuity and measur...This article deals with a new fractional nonlinear delay evolution system driven by a hemi-variational inequality in a Banach space.Utilizing the KKM theorem,a result concerned with the upper semicontinuity and measurability of the solution set of a hemivariational inequality is established.By using a fixed point theorem for a condensing setvalued map,the nonemptiness and compactness of the set of mild solutions are also obtained for such a system under mild conditions.Finally,an example is presented to illustrate our main results.展开更多
In this paper, a new auxiliary equation method is proposed. Combined with the mapping method, abundant periodic wave solutions for generalized Klein-Gordon equation and Benjamin equation are obtained. They are new typ...In this paper, a new auxiliary equation method is proposed. Combined with the mapping method, abundant periodic wave solutions for generalized Klein-Gordon equation and Benjamin equation are obtained. They are new types of periodic wave solutions which are rarely found in previous studies. As <em>m</em> → 0 and <em>m</em> → 1, some new types of trigonometric solutions and solitary solutions are also obtained correspondingly. This method is promising for constructing abundant periodic wave solutions and solitary solutions of nonlinear evolution equations (NLEEs) in mathematical physics.展开更多
With the help of an extended mapping approach and a linear variable separation method,new families ofvariable separation solutions with arbitrary functions for the(3+1)-dimensional Burgers system are derived.Based ont...With the help of an extended mapping approach and a linear variable separation method,new families ofvariable separation solutions with arbitrary functions for the(3+1)-dimensional Burgers system are derived.Based onthe derived exact solutions,some novel and interesting localized coherent excitations such as embed-solitons are revealedby selecting appropriate boundary conditions and/or initial qualifications.The time evolutional properties of the novellocalized excitation are also briefly investigated.展开更多
In this paper, parabolic type differential inclusions with time dependent ape considered and this problem is related to the study of the nonlinear distributed parameter central systems. An existence theorem of mild-so...In this paper, parabolic type differential inclusions with time dependent ape considered and this problem is related to the study of the nonlinear distributed parameter central systems. An existence theorem of mild-solutions is proved, and a property of the solution set is given. The directions and the results by J.P. Aubin et al. are generalized and improved.展开更多
New high throughput DNA technologies resulted in a disproportion between the high number of scored markers for the mapping populations and relatively small sizes of the genotyped populations. Correspondingly, the numb...New high throughput DNA technologies resulted in a disproportion between the high number of scored markers for the mapping populations and relatively small sizes of the genotyped populations. Correspondingly, the number of markers may, by orders of magnitude, exceed the threshold of recombination resolution achievable for a given population size. Hence, only a small part of markers can be genuinely ordered in the map. The question is how to choose the most informative markers for building such a reliable “skeleton” map. We believe that our approach provides a solution to this difficult problem due to: a) powerful tools of discrete optimization for multilocus ordering;b) a verification procedure, which is impossible without fast and high-quality optimization, to control the map quality based on re-sampling techniques;c) an interactive algorithm of marker clustering in complicated situations caused by significant deviation of recombination rates between markers of non-homologous chromosomes from the expected 50% (referred to as quasi-linkage or pseudo-linkage);and d) an algorithm for detection and removing excessive markers to increase the stability of multilocus ordering.展开更多
The seismicity of the Arabian plate, which is the aim of this paper, is controlled by the ZagrosTaurus collision zone in the North, the Indian expansion zone and the Arab golf in the South and the East, the Dead Sea F...The seismicity of the Arabian plate, which is the aim of this paper, is controlled by the ZagrosTaurus collision zone in the North, the Indian expansion zone and the Arab golf in the South and the East, the Dead Sea Fault, the North continuity of the Red Sea, and the Syrian rift, which links the rigid Arabian plate to the mobile ophiolite belt of Cyprus-Southern Turkey in the West. These major elements with their related fracture system, make the Arabian plate an important seismic centre. To attain our purpose, a variable methodology is used in: measurements of movement rate-displacement in the field, the analysis of historical and recent seismic data, and physical effects on the structures. The movement rate-displacement, calculated in the field by different specialists, varies from 2 to 6 mm/year. This rate increases from 2 - 3 mm/year in the North, to 6 mm in the South. These estimations are confirmed by historical seismic data, the recent seismic recorded by the Arab seismic centers, and physical effects on the building structures in the region. The analysis of historical and recent seismic data recorded in the seismic centre show that the seismicity in this plate, tend to fade out with time. This result is in agreement with recent estimations on the movement rate, and in line with the decrease of major seismic intensity, which has occurred during the last millennium. A conclusion of time-evolution seismicity is traced, and a seismic zoning map, for the Arabian plate, using movement rate, seismic data, and tectono-geodynamic analysis, is proposed.展开更多
文摘This study presents a reflective bibliometric review of 1457 peer-reviewed articles published in the Journal of Psychology in Africa(2008-2024,17 years),using a Meta-Editorial Mapping Framework(MEMF)analysis.The MEMF integrates citation metrics,keyword novelty ratios,TF-IDF weighting,and cluster-based topic modeling to trace long-term thematic trends and editorial evolution.Findings reveal sustained attention to foundational domains such as mental health,education,and identity,alongside a gradual integration of emergent themes including digital well-being,organizational behavior,and post-pandemic adaptation.Articles with moderate topical novelty(40%-60% new keywords)achieved the highest citation and usage metrics,suggesting that integrative innovation enhances scholarly impact.Clustering analyses indicate that the journal’s content forms overlapping conceptual domains rather than isolated silos.These insights contribute to editorial strategy,authorial positioning,and the future design of regional academic platforms.Moreover,the findings provide evidence supporting the use of the MEMF as a replicable tool for meta-editorial analysis across disciplinary and geographic boundaries.
基金Supported by the National Natural Science Foundation of China(No.90820302,60805027)the Provincial Natural Science Foundation of Hunan(No.12JJ3064)+1 种基金the Construct Program of the Key Discipline in Hunan Province(No.201176)the Planned Science and Technology Project of Hunan Province(No.2011SK3135,2012FJ3059)
文摘Map building by multi-robot is very important to accomplish autonomous navigation,and one of the basic problems and research hotspots is how to merge the maps into a single one in the field of multi-robot map building.A novel approach is put forward based on adaptive differential evolution to map building for the multi-robot system.The multi-robot mapping-building system adopts the methods of decentralized exploration and concentrated mapping.The adaptive differential evolution algorithm is used to search in the space of possible transformation,and the iterative search is performed with the goal of maximizing overlapping regions.The map is translated and rotated so that the two maps can be overlapped and merged into a single global one successfully.This approach for map building can be realized without any knowledge of their relative positions.Experimental results show that the approach is effective and feasibile.
基金Supported by the National Natural Science Foundation of China(12201368,62376252)Key Project of Natural Science Foundation of Zhejiang Province(LZ22F030003)Zhejiang Province Leading Geese Plan(2024C02G1123882,2024C01SA100795).
文摘With the urgent need to resolve complex behaviors in nonlinear evolution equations,this study makes a contribution by establishing the local existence of solutions for Cauchy problems associated with equations of mixed types.Our primary contribution is the establishment of solution existence,illuminating the dynamics of these complex equations.To tackle this challenging problem,we construct an approximate solution sequence and apply the contraction mapping principle to rigorously prove local solution existence.Our results significantly advance the understanding of nonlinear evolution equations of mixed types.Furthermore,they provide a versatile,powerful approach for tackling analogous challenges across physics,engineering,and applied mathematics,making this work a valuable reference for researchers in these fields.
基金the National Key Research and Development Program of China(No.2016YFB0700505)the National Natural Science Foundation of China(No.51571020).
文摘The hot deformation behavior of GH3230 superalloy under selected deformation conditions ranging from 950 to 1150℃with strain rates ranging from 0.01 to 10 s^(–1)was studied through isothermal hot compression experiments.Based on the obtained flow stresses,a strain-compensated Arrhenius-type model was developed for the description of hot deformation behavior,and the consistency of the predicted flow stresses with the experimental values confirms the accuracy of the developed model.Furthermore,the processing maps were constructed and classified into the instability domain,low-dissipation stability domain and high-dissipation stability domain in accordance with the dynamic material model and the instability criterion.Microstructure observations indicated that the instability domain exhibits the adiabatic shear bands formation,and the low-power dissipation domain exhibits partial dynamic recrystallization(DRX),with the temperature increase/strain rate decrease being favorable for the DRX.The high-dissipation stability domain was occupied by uniformly fine equiaxed grains,and was identified as the optimal processing window,which corresponds to the deformation conditions at 1070–1150℃ with strain rates ranging from 0.01 to 0.15 s^(–1).Moreover,various DRX mechanisms are observed to occur during the hot deformation,which include the discontinuous dynamic recrystallization,characterized by nucleation at bulged boundaries,the continuous dynamic recrystallization with subgrain progressive rotation and the particle stimulated nucleation mechanism with stimulated nucleation of carbide particles.
基金financed by the National Natural Science Foundation of China(No.42172084)China Postdoctoral Science Foun dation(2021M693191)+1 种基金Geological Exploration Fund of the Qinghai Provincial,China(No.2021074001ky001)China Scholarship Council(CSC)。
文摘The Eastern Kunlun Orogenic Belt(EKOB)in the Northern Tibet Plateau hosts a wide variety of metal deposits related to the Late Paleozoic to Mesozoic magmatism.In this study,we investigate the spatiotemporal distribution of the Late Paleozoic to Mesozoic granitic rocks and associated metal deposits in the EKOB and provide a comprehensive compilation of the geochronological,geochemical and isotopic data on these rocks.We compute regional zircon Hf isotope and crustal thickness maps from the data,based on which a comprehensive model is proposed involving subduction(ca.270–240 Ma),continental collision(ca.240–224 Ma),and post-collisional extension(ca.224–200 Ma)for the Late Paleozoic to Mesozoic Paleo-Tethys evolution in the EKOB.Zircon Hf isotopic and crustal thickness mapping of Late Paleozoic to Mesozoic magmatic rocks was carried out to evaluate their spatio-temporal and genetic links with the regional metallogeny.The polymetallic Fe-skarn and porphyry Cu(Mo)deposits in the EKOB are located above the Moho uplift region,featuring a comparatively thin crust.Granites associated with porphyry Cu(Mo)and polymetallic Fe skarn mineralization are commonly characterized by highε_(Hf)(t)and younger T_(DM)cvalues,whereas granite related to Cu-Mo-Sn skarn deposits exhibit more variableε_(Hf)(t)values,T_(DM)c ages,and the crust thickness,which suggest that more crustal materials contributed to the formation of Cu-Mo-Sn skarn deposits than those for porphyry Cu(Mo)and polymetallic Fe skarn mineralization.In contrast,vein-type Au deposits are located primarily where the Moho surface displays a depression,i.e.,where the continental crust is relatively thick.The magmatic rocks associated with Au mineralization are characterized by lowε_(Hf)(t)and high T_(DM)cvalues,representing reworked ancient crustal components,similar to those associated with porphyry Mo and epithermal Ag-Pb-Zn-(Au)deposits.Our study indicates that the emplacement of magmatic-hydrothermal deposits was controlled by the crustal structure and magma sources.
基金financially supported by the National Natural Science Foundation of China (No. 51772176)the Science and Technology Development Project of Shandong Province (No.2019JZZY010303)the Shandong Natural Science(No. ZR2015EM013)。
文摘Defect existing form and its evolution play an important role in the thermoelectric transport process. Here different forms of Pb into the Sn Se system were introduced in order to improve the thermoelectric and mechanical properties of Sn Se. Pb/Sn Se samples were fabricated by vacuum melting, solid phase diffusion,spark plasma sintering and annealing treatment. The element valence mapping diagram and the X-ray photoelectron spectra(XPS) characteristic peaks of Pb show that a certain amount of elemental Pb exists in the initial state, and evolves into Pb^(2+)ion after annealing treatment. The micro-structure evolution leads to significant enhancement of the power factor and the ZT value. The power factor(PF) and the ZT value for Pb/Sn Se increases to 623 μW/m/K^(2) and 1.12 at 773 K after annealing treatment, respectively.Compared with Sn Se matrix, the hardness and fracture toughness of Pb/Sn Se samples increased by about40% and 10%, respectively. Reasonable control of microstructure evolution is expected to be a design idea to improve thermoelectric and mechanical properties of Sn Se.
文摘In this paper we introduce the evolution law of thinking-neural network attractor in the field of thinking dynamics,a new idea about the attractor evolution using evolutional mapping transformation is given on the bases of generalized isologous concept. The idea is connected with the intuitive thinking.This paper lays a foundation for the further studying of the brain thinking process.
基金financial support of National Natural Science Foundation of China(No.51971149)the funding from Science and Technology Innovation Commission of Shenzhen(Nos.KQJSCX20180328095612712,GJHZ20190822095418365)+1 种基金Guangdong Basic and Applied Basic Research Foundation(Nos.2020A1515110869 and 2019A1515110515)Shenzhen-Hong Kong Science and Technology Innovation Cooperation Zone Shenzhen Park Project(No.HZQB-KCZYB-2020030)。
文摘As a revolutionary industrial technology,additive manufacturing creates objects by adding materials layer by layer and hence can fabricate customized components with an unprecedented degree of freedom.For metallic materials,unique hierarchical microstructures are constructed during additive manufacturing,which endow them with numerous excellent properties.To take full advantage of additive manufacturing,an in-depth understanding of the microstructure evolution mechanism is required.To this end,this review explores the fundamental procedures of additive manufacturing,that is,the formation and binding of melt pools.A comprehensive processing map is proposed that integrates melt pool energy-and geometry-related process parameters together.Based on it,additively manufactured microstructures are developed during and after the solidification of constituent melt pool.The solidification structures are composed of primary columnar grains and fine secondary phases that form along the grain boundaries.The post-solidification structures include submicron scale dislocation cells stemming from internal residual stress and nanoscale precipitates induced by intrinsic heat treatment during cyclic heating of adjacent melt pool.Based on solidification and dislocation theories,the formation mechanisms of the multistage microstructures are thoroughly analyzed,and accordingly,multistage control methods are proposed.In addition,the underlying atomic scale structural features are briefly discussed.Furthermore,microstructure design for additive manufacturing through adjustment of process parameters and alloy composition is addressed to fulfill the great potential of the technique.This review not only builds a solid microstructural framework for metallic materials produced by additive manufacturing but also provides a promising guideline to adjust their mechanical properties.
基金supported by the Project of National Key Laboratory for Precision Hot Processing of Metals, Harbin Institute of Technology, China (No. 6142909190207)Shaanxi Key Laboratory of High-performance Precision Forming Technology and Equipment (SKL-HPFTE), China (No. PETE-2019-KF-01)。
文摘High strength β titanium alloys are widely used in large load bearing components in the aerospace field. At present, large parts are generally formed by die forging. Different initial microstructures and deformation process parameters will significantly affect the flow behavior. To precisely control the microstructures, researchers have conducted many studies to analyze the microstructure evolution law and deformation mechanism during hot compression. This review focuses on the microstructure evolution of high strength β titanium alloys during hot deformation, including dynamic recrystallization and dynamic recovery in the single-phase region and the dynamic evolution of the α phase in the two-phase region. Furthermore, the optimal hot processing regions, instability regions,and the relationship between the efficiency of power dissipation and the deformation mechanism in the hot processing map are summarized. Finally, the problems and development direction of using hot processing maps to optimize process parameters are also emphasized.
基金financially supported by the National Program on Key Basic Research Project of China (No.2012CB619504)the National Natural Science Foundation of China (No.51274046)
文摘The hot deformation behavior of Al-Cu-Li alloy was investigated by hot compression tests in the temperature range of 340-500℃ with strain rate of 0.001-10.000 s^(-1).Based on the dynamic materials model(DMM),processing maps of the test alloy were developed for optimizing hot processing parameters.The optimum parameters of hot deformation for Al-Cu-Li alloy are at temperature of 400-430℃and strain rate of about 0.100 s^(-1),with efficiency of power dissipation of around 30%.The microstructural manifestation of the alloy deformed in instability domains is flow localization,and dynamic softening first occurs in flow localizations structure.In stable domains,dynamic recovery(DRV) and dynamic recrystallization(DRX) are the main microstructural evolution mechanism.DRX is gradually strengthened with the increase in deformation temperature and the decrease in strain rate.During hot deformation,the DRX mechanism of Al-Cu-Li alloy is dominated by continuous DRX(CDRX).A DRX model of Al-Cu-Li alloy is proposed based on the microstructural evolution process of the test alloy.
基金supported by the Hunan Provincial Natural Science Foundation Project(No.2024JJ8320)the Hunan Province Natural Resources Science and Technology Plan Project(No.20230151ST)+1 种基金the Hunan Province Science Popularization Special Plan(Science and Technology Talent Support Project)(No.2023TJ-N16)the Open Fund of Hunan Provincial Key Laboratory for Remote Sensing Monitoring of Ecological Environment in Dongting Lake Area(No.DTH Key Lab.2021-28)。
文摘Using historical topographic maps and aerospace remote sensing data since the 1930s,this study investigates the spatial and temporal evolution of Dongting Lake beach.The evolution characteristics of the beaches in different regions and the related formation mechanism were also analyzed.The results show that Dongting Lake beach expanded from 1622.17 km^(2)in 1938 to 1962.28 km^(2)in 2018.With the addition of 980.96 km^(2)of reclaimed high bay beach,the beach area increased by 1321.07km^(2).However,the change process fluctuated somewhat rather than continuously increased.Substantial expansion of the beach area occurred during 1938-1948 and 1958-1998,while slow contraction of the beach area occurred during 1948-1958 and 1998-2018.Dongting Lake beach was dominated by terrigenous debris,the sedimentary types included lacustrine deposits,river alluvial deposits,floodplain and main channel deposits,and river-lake interaction deposits.The rapid expansion occurred in the estuary delta of the east branch of the Ouchi River,which advanced 38.55 km from the estuary toward the lake over the past 90 years.The causes of the changes in the beach included beach reclamation,sediment changes,and lake sand mining.Seventy embankments(covering 2057.77 km^(2))have been enclosed in the Dongting Lake area since 1930s,of which the high bay beach covered an area of 980.96km^(2).The amount of sediment deposited in Dongting Lake has reached 230857×10^(4) m^(3) since 1950s,which is equivalent to an average deposition height of 0.85 m on the lake's bottom.The mining of lake sand caused the beach to shrink,and the proportion of the beach area decreased from 77.18%in 1998 to 72.60%in 2018.The results of this study provide objective data for protecting the lakeshore's ecosystem and biodiversity and supporting the ecological restoration and environmental protection of the Yangtze River Basin.
基金financially supported by the National Key Research and Development Program of China(No.2016YFB0301300)the National Natural Science Foundation of China(Nos.51974028 and U1602271)。
文摘By means of isothermal compression at temperatures in the range of 650-900℃and strain rates in the range of 0.001-1 s^(-1),the dynamic recrystallization behavior and microstructural evolution of a Cu-3.28 Ni-0.6 Si-0.22 Zn-0.11 Cr-0.04 P(wt%)alloy designed by a machine learning method were investigated.A semiempirical constitutive equation,processing maps and an average activation energy were generated.The microstructure under different conditions and the effect of strain rate on the texture of the alloy at 800-900℃were observed.The results show that the suitable temperature is800-900℃;when the strain is less than 0.4,the appropriate strain rate is 0.01-0.5 s^(-1);and when the strain is greater than 0.4,the appropriate strain rate is below0.05 s^(-1).After deformation at 800℃,the main texture changed from{112}<111>of copper to a uniform distribution with the increase in strain rate,but the sample did not have obvious texture after deformation at 850 and900℃.The above results can provide a reference for the selection of process parameters.
基金This work is supported by the Liaoning Province Programs of Science and Technology Development(No.2019JH2/10100009).
文摘The hot deformation behavior and microstructure evolution of an Fe–30Cr–2Mo ultra-pure super ferritic stainless steel were investigated at the temperature range of 950–1150℃ and strain rate varying from 0.01 to 10 s^(−1).A strain compensated constitutive equation based on the Arrhenius-type model was established to predict the flow stress.The hot processing map based on the dynamic materials model was achieved to identify the optimum processing parameters.In addition,the features of microstructure evolution combined with the processing map were systematically investigated.The experimental results revealed that the flow stress increased with decreasing deformation temperature or increasing strain rate.Dynamic recovery was confirmed to be the predominant softening mechanism.The values of flow stress predicted by the strain compensated constitutive equation agreed well with the experimental values.The extent of dynamic recrystallization and recrystallized grain size increased with increasing deformation temperature or decreasing strain rate,and the continuous dynamic recrystallization was attributed to be the predominant mechanism of recrystallization during hot deformation.The optimum hot working parameters were determined to be the deformation temperature of 1070–1150℃ and strain rate of 0.1–1 s^(−1) with a peak power dissipation efficiency of 42%.
基金Supported by the China National Science and Technology Major Project(2016ZX05004-002)the PetroChina Science and Technology Major Project(2018A-0103)
文摘Ancient marine carbonates experienced complex modifications,making it difficult to identify reservoir genesis and effective porosity before hydrocarbon migration.To solve these issues,we used element mapping and carbonate mineral laser U-Pb radiometric dating techniques to study the diagenetic environments based on geochemistry and diagenesis-porosity evolution based on geochronology of the dolomite reservoir of the Sinian Qigebrak Formation,northwest Tarim Basin.Two major understandings were obtained as follows:(1)Supported by petrographic observations,the element mapping,stable isotopes,strontium isotope,and cathodoluminescence tests were performed on different phases of dolomite cements precipitated in vugs and dissolved fissures.The results show that the dolomite reservoirs of the Qigebrak Formation went through freshwater,marine,extremely shallow burial,burial and hydrothermal diagenetic environments after synsedimentary dolomitization;the reservoir spaces were mainly formed in the synsedimentary period(primary pores)and freshwater environment(supergene dissolution pores)before burial;whereas the marine,burial and hydrothermal environments caused the gradual filling of reservoir space by dolomite cements.(2)Based on the above understandings,each phase of dolomite cement precipitated in the reservoir space was dated by the U-Pb radiometric dating technique,and the diagenesis-porosity evolution curves constrained by geochronology were established.The loss of reservoir porosity mainly occurred in the early Caledonian,and during the peak period of hydrocarbon generation of Yuertusi Formation source rock,the reservoirs still maintained at a porosity of 6%?10%.The above understandings provide a certain basis for the evaluation of accumulation effectiveness of the Sinian Qigebrak Formation,northwestern Tarim Basin,and provide a case for the application of mapping and dating techniques in the study of ancient carbonate reservoirs.
基金supported by the National Natural Science Foundation of China(11471230,11671282)。
文摘This article deals with a new fractional nonlinear delay evolution system driven by a hemi-variational inequality in a Banach space.Utilizing the KKM theorem,a result concerned with the upper semicontinuity and measurability of the solution set of a hemivariational inequality is established.By using a fixed point theorem for a condensing setvalued map,the nonemptiness and compactness of the set of mild solutions are also obtained for such a system under mild conditions.Finally,an example is presented to illustrate our main results.
文摘In this paper, a new auxiliary equation method is proposed. Combined with the mapping method, abundant periodic wave solutions for generalized Klein-Gordon equation and Benjamin equation are obtained. They are new types of periodic wave solutions which are rarely found in previous studies. As <em>m</em> → 0 and <em>m</em> → 1, some new types of trigonometric solutions and solitary solutions are also obtained correspondingly. This method is promising for constructing abundant periodic wave solutions and solitary solutions of nonlinear evolution equations (NLEEs) in mathematical physics.
基金the Natural Science Foundation of Zhejiang Province under Grant Nos.Y604106 and Y606181the Foundation of New Century"151 Talent Engineering"of Zhejiang Province+1 种基金the Scientific Research Foundation of Key Discipline of Zhejiang Provincethe Natural Science Foundation of Zhejiang Lishui University under Grant No KZ06006
文摘With the help of an extended mapping approach and a linear variable separation method,new families ofvariable separation solutions with arbitrary functions for the(3+1)-dimensional Burgers system are derived.Based onthe derived exact solutions,some novel and interesting localized coherent excitations such as embed-solitons are revealedby selecting appropriate boundary conditions and/or initial qualifications.The time evolutional properties of the novellocalized excitation are also briefly investigated.
文摘In this paper, parabolic type differential inclusions with time dependent ape considered and this problem is related to the study of the nonlinear distributed parameter central systems. An existence theorem of mild-solutions is proved, and a property of the solution set is given. The directions and the results by J.P. Aubin et al. are generalized and improved.
文摘New high throughput DNA technologies resulted in a disproportion between the high number of scored markers for the mapping populations and relatively small sizes of the genotyped populations. Correspondingly, the number of markers may, by orders of magnitude, exceed the threshold of recombination resolution achievable for a given population size. Hence, only a small part of markers can be genuinely ordered in the map. The question is how to choose the most informative markers for building such a reliable “skeleton” map. We believe that our approach provides a solution to this difficult problem due to: a) powerful tools of discrete optimization for multilocus ordering;b) a verification procedure, which is impossible without fast and high-quality optimization, to control the map quality based on re-sampling techniques;c) an interactive algorithm of marker clustering in complicated situations caused by significant deviation of recombination rates between markers of non-homologous chromosomes from the expected 50% (referred to as quasi-linkage or pseudo-linkage);and d) an algorithm for detection and removing excessive markers to increase the stability of multilocus ordering.
文摘The seismicity of the Arabian plate, which is the aim of this paper, is controlled by the ZagrosTaurus collision zone in the North, the Indian expansion zone and the Arab golf in the South and the East, the Dead Sea Fault, the North continuity of the Red Sea, and the Syrian rift, which links the rigid Arabian plate to the mobile ophiolite belt of Cyprus-Southern Turkey in the West. These major elements with their related fracture system, make the Arabian plate an important seismic centre. To attain our purpose, a variable methodology is used in: measurements of movement rate-displacement in the field, the analysis of historical and recent seismic data, and physical effects on the structures. The movement rate-displacement, calculated in the field by different specialists, varies from 2 to 6 mm/year. This rate increases from 2 - 3 mm/year in the North, to 6 mm in the South. These estimations are confirmed by historical seismic data, the recent seismic recorded by the Arab seismic centers, and physical effects on the building structures in the region. The analysis of historical and recent seismic data recorded in the seismic centre show that the seismicity in this plate, tend to fade out with time. This result is in agreement with recent estimations on the movement rate, and in line with the decrease of major seismic intensity, which has occurred during the last millennium. A conclusion of time-evolution seismicity is traced, and a seismic zoning map, for the Arabian plate, using movement rate, seismic data, and tectono-geodynamic analysis, is proposed.
