Based on comprehensive analyses of seismic and tog data, this study indicates that mainty four widespread angutar to minor angutar unconformities (Tg8, Tg51, Tg5 and Tg3) were formed during the Pateozoic. Through th...Based on comprehensive analyses of seismic and tog data, this study indicates that mainty four widespread angutar to minor angutar unconformities (Tg8, Tg51, Tg5 and Tg3) were formed during the Pateozoic. Through the interpretation of structural unconformities, calcutation of eroded thickness, correction of pataeo-water depth and compaction and compiration of the Earty Paleozoic structural maps, the Earty Paleozoic stope break bert (geomorphologic unit) of the Tarim Basin is subdivided into uptift area, subaqueous uptift area, rift slope break belt, flexure stope break bert (stope bert), depression area and deep basin area. Pataeogeomorphotogy of the Cambrian-Early Ordovician was approximately in EW trend within which three tectonic units inctuding the Tabei Pataeo-uptift, the northern Depressional Belt and the southern Pataeo-uptift developed respectivety and are grouped into two stope break systems namety as the Tabei Pataeo-uptift and the southern Pataeo-uptift. These tectonic units obviousty controt the deposition of isolated platform, open platform, restricted ptatform and deep basin. Influenced by extrusion in the Mid-Late Ordovician, the southern and northern subaqueous uptifts graduat[y etevated and then were eroded. Resuttant[y two slope break systems devetoped, namely as the northern and central Pataeo-uptifts which obviousty controtled the deposition of provenance area, isolated ptatform, mixed continental shelf, slope and basin facies. The intensive extrusion of the Mid-Late Ordovician reads to significant tectonic deformation of the Tarim Basin: large area of uplifting and erosion and development of EW trending anticline and syncline. Deposition of shore, tidal fiat, delta, shallow marine clastics and deep marine facies is obviously controlled by the Tabei, the southern and the Tadong Palaeo-uplifts. Slope break systems control development of stratigraphic unconformity and thus truncation and onlap unconformity zones become favorable areas in a palaeo-uplift and at a palaeo-slope belt for forming important unconformity traps; Whereas slope (slope break) belt along a palaeo-uplift margin is a geomorphologic unit where high-energy sedimentary facies widely develops, such as reef, oolitic sandy clastics or bioclastic limestone beach bar facies, thus litho-structural composite hydrocarbon accumulations usually develop when tectonic condition is suitable. In addition, large-scale palaeo-uplifts are the most favourable areas for hydrocarbon accumulation development.展开更多
By means of an improved mapping method and a variable separation method, a series of variable separation solutions including solitary wave solutions, periodic wave solutions and rational function solutions) to the (...By means of an improved mapping method and a variable separation method, a series of variable separation solutions including solitary wave solutions, periodic wave solutions and rational function solutions) to the (2+1)-dimensional breaking soliton system is derived. Based on the derived solitary wave excitation, we obtain some special annihilation solitons and chaotic solitons in this short note.展开更多
A submerged cavitation water jet(SCWJ)is an effective method to recycle solid propellant from obsolete solid engines by the breaking method.Solid propellant's breaking modes and mechanical process under SCWJ impac...A submerged cavitation water jet(SCWJ)is an effective method to recycle solid propellant from obsolete solid engines by the breaking method.Solid propellant's breaking modes and mechanical process under SCWJ impact are unclear.This study aims to understand those impact breaking mechanisms.The hydroxyl-terminated polybutadiene(HTPB)propellant was chosen as the research material,and a self-designed test system was used to conduct impact tests at four different working pressures.The high-speed camera characterized crack propagation,and the DIC method calculated strain change during the impact process.Besides,micro and macro fracture morphologies were characterized by scanning electron microscope(SEM)and computed tomography(CT)scanning.The results reveal that the compressive strain concentration region locates right below the nozzle,and the shear strain region distributes symmetrically with the jet axis,which increases to 4% at first 16th ms,the compressive strain rises to 2% and 6% in the axial and transverse direction,respectively.The two tensile cracks formed first at the compression strain concentrate region,and there generate many shear cracks around the tensile cracks,and those shear cracks that develop and aggregate cause the cracks to become wider and cut through the tensile cracks,forming the tensile-shear cracks and the impact parts eventually fail.The HTPB propellant forms a breaking hole shaped conical after impact 10 s.The mass loss increases by 17 times at maximum,with the working pressure increasing by three times.Meanwhile,the damage value of the breaking hole remaining on the surface increases by 7.8 times while 2.9 times in the depth of the breaking hole.The breaking efficiency is closely affected by working pressures.The failure modes of HTPB impacted by SCWJ are classified as tensile crack-dominated and tensile-shear crack-dominated damage mechanisms.展开更多
This paper investigates the breaking point between fast- and slow-light in a degenerate two-level atomic system, where fast-light can be converted to slow-light arbitrarily on a single transition line by adjusting the...This paper investigates the breaking point between fast- and slow-light in a degenerate two-level atomic system, where fast-light can be converted to slow-light arbitrarily on a single transition line by adjusting the strength of the pumping field. An equivalent incoherent pumping rate is introduced in this simplified theoretical model which exploits the dependence of this feature. The experimental observation is presented as evidence of the breaking point where the injected power is about 0.08 mW.展开更多
This paper studies the effects of break through state and system rigidity on vibration and noise in blanking, suggests the describtion of the generation state of breakthrough by the unloading gradient obtained from t...This paper studies the effects of break through state and system rigidity on vibration and noise in blanking, suggests the describtion of the generation state of breakthrough by the unloading gradient obtained from the force stroke curve, discusses the effect of the relation between the unloading gradient and the vibration system rigidity on vibration, and gives the optimal relationship between these two factors to efficiently reduce the vibration, and this conclusion is verified by noise experiments done by using two presses of unequal rigidity to carry out the same blanking.展开更多
In the field of automobile manufacture, during the aluminum alloy cutting, chip forming and breaking process are very complicated. It is affected by many facto rs. Automatic machining process can not be carried throug...In the field of automobile manufacture, during the aluminum alloy cutting, chip forming and breaking process are very complicated. It is affected by many facto rs. Automatic machining process can not be carried through if the chip enlaces t he workpiece or the tool. So the chip control and breaking are key technology. P CD tool has many traits, such as high cutting efficiency, machining precision an d wearability. It is desired that it be used for machining coloured metals.The p aper present the study of prediction of chip breaking when PCD Tool cutting alum inum alloy with chip breaker. In the process of cutting, the method of chip brea king is up-curl-dominant chip. Therefore, based on the theory of chip breaking with chip breaker, used the cutting condition of chip breaking, this paper dedu ce the chip breaking mathematical model when cutting aluminum alloy, that is to say, the chip breaker parameters(Angle of chip break,chip groove width, bevel a ngle, the normal rake angle of chip groove, tool cutting edge angle)influence th e critical feed rate. The following conclusion can be made from theoretic analys is. The critical feed rate will decrease when the Angle of chip break and bevel angle and the normal rake angle of chip groove and tool cutting edge angle incre ase. The critical feed rate will increase when chip groove width increase. The e xperimental results are well coincided with the theoretic ones, it is proved tha t the predicting system is correct.展开更多
In this work, starting from the (G'/G)-expansion method and a variable separation method, a new non-traveling wave general solutions of the (2+1)-dimensional breaking soliton system are derived. By selecting appro...In this work, starting from the (G'/G)-expansion method and a variable separation method, a new non-traveling wave general solutions of the (2+1)-dimensional breaking soliton system are derived. By selecting appropriately the arbitrary functions in the solutions, special soliton-structure excitations and evolutions are studied.展开更多
To restore the distribution systems in emergency states with the minimum load shedding, a novel Tabu search approach is put forward. The set of tripped switches is used as candidate solution. Some virtual tripped node...To restore the distribution systems in emergency states with the minimum load shedding, a novel Tabu search approach is put forward. The set of tripped switches is used as candidate solution. Some virtual tripped nodes are defined at the ends of the terminal nodes and by the source nodes. The neighborhood searching is committed by moving a tripped switch to the adjacent node of its upper stream and down stream, respectively. A Tabu list is formed for the tripped switches. The index is to energize as much as possible loads with as less as possible operated times. The electrical limitations and the voltage criterions are used as constrictions. The global aspiration criterion is adopted. An example is given, which shows that the proposed approach is feasible and can deal with complicated indexes.展开更多
Adding a U(1) symmetry breaking term √V(λ1a0 + λ1*a0) + √V(λ2b0 + λ2*b0) to Bogoliubov's truncated Hamiltonian HB for a weakly interacting coupled Bose system, by using the mean-field approximation r...Adding a U(1) symmetry breaking term √V(λ1a0 + λ1*a0) + √V(λ2b0 + λ2*b0) to Bogoliubov's truncated Hamiltonian HB for a weakly interacting coupled Bose system, by using the mean-field approximation rather than the c-number approximation, we And that, via a Feshbach resonance at zero temperature, the states of the coupled Bose system are generalized SU(1,1) SU(1,1) coherent states. The Bose-Einstein condensation occurs in response to the spontaneous U(1) symmetry breaking.展开更多
The cavitation cloud impingement of the jet in the rock breaking process was experimentally investigated to reveal the jet erosion mechanism in drilling of petroleum exploitation. Serial erosion tests and flow visuali...The cavitation cloud impingement of the jet in the rock breaking process was experimentally investigated to reveal the jet erosion mechanism in drilling of petroleum exploitation. Serial erosion tests and flow visualization were performed, where the cavitation cloud motion in the erosion crater was obtained with the designed transparent specimen. Various erosion patterns were identified in the whole erosion process based on the eroded specimen topography. The shallow eroded crater with a shrinking erosion area is generated by the combination of impinging and scattering cavitation clouds. The increase of l_(d) promotes the development of cavitation cloud σ_(c) but reduces the impingement frequency f_(d), suggesting that the jet aggressive ability is enhanced when the balance between σ_(c) and f_(d) is reached. The cavitation cloud motion in the erosion crater was investigated with the transparent specimen. The erosion in the crater at shorter exposure periods T_(e) is generated by the combination of impingement and restricted scattering of cavitation clouds. With the continuous development of the erosion damage, the jet's aggressive ability is diminished due to the erosion expansion on sandstone, where the cavitation clouds impinge on the target and then collapse and vanish without restricted scattering.展开更多
Topologically nontrivial Fe-based superconductors attract extensive attentions due to their ability of hosting Majorana zero modes(MZMs)which could be used for topological quantum computation.Topological defects such ...Topologically nontrivial Fe-based superconductors attract extensive attentions due to their ability of hosting Majorana zero modes(MZMs)which could be used for topological quantum computation.Topological defects such as vortex lines are required to generate MZMs.Here,we observe the robust edge states along the surface steps of CaKFe_(4)As_(4).Remarkably,the tunneling spectra show a sharp zero-bias peak(ZBP)with multiple integerquantized states at the step edge under zero magnetic field.We propose that the increasing hole doping around step edges may drive the local superconductivity into a state with possible spontaneous time-reversal symmetry breaking.Consequently,the ZBP can be interpreted as an MZM in an effective vortex in the superconducting topological surface state by proximity to the center of a tri-junction with different superconducting order parameters.Our results provide new insights into the interplay between topology and unconventional superconductivity,and pave a new path to generate MZMs without magnetic field.展开更多
Biogeographical barriers to gene flow are central to plant phylogeography.In East Asia,plant distribution is greatly influenced by two phylogeographic breaks,the Mekong-Salween Divide and Tanaka-Kaiyong Line,however,f...Biogeographical barriers to gene flow are central to plant phylogeography.In East Asia,plant distribution is greatly influenced by two phylogeographic breaks,the Mekong-Salween Divide and Tanaka-Kaiyong Line,however,few studies have investigated how these barriers affect the genetic diversity of species that are distributed across both.Here we used 14 microsatellite loci and four chloroplast DNA fragments to examine genetic diversity and distribution patterns of 49 populations of Populus rotundifolia,a species that spans both the Mekong-Salween Divide and the Tanaka-Kaiyong Line in southwestern China.Demographic and migration hypotheses were tested using coalescent-based approaches.Limited historical gene flow was observed between the western and eastern groups of P.rotundifolia,but substantial flow occurred across both the Mekong-Salween Divide and Tanaka-Kaiyong Line,manifesting in clear admixture and high genetic diversity in the central group.Wind-borne pollen and seeds may have facilitated the dispersal of P.rotundifolia following prevalent northwest winds in the spring.We also found that the Hengduan Mountains,where multiple genetic barriers were detected,acted on the whole as a barrier between the western and eastern groups of P.rotundifolia.Ecological niche modeling suggested that P.rotundifolia has undergone range expansion since the last glacial maximum,and demographic reconstruction indicated an earlier population expansion around 600 Ka.The phylogeographic pattern of P.rotundifolia reflects the interplay of biological traits,wind patterns,barriers,niche differentiation,and Quaternary climate history.This study emphasizes the need for multiple lines of evidence in understanding the Quaternary evolution of plants in topographically complex areas.展开更多
Urea-assisted natural seawater electrolysis is an emerging technology that is effective for grid-scale carbon-neutral hydrogen mass production yet challenging.Circumventing scaling relations is an effective strategy t...Urea-assisted natural seawater electrolysis is an emerging technology that is effective for grid-scale carbon-neutral hydrogen mass production yet challenging.Circumventing scaling relations is an effective strategy to break through the bottleneck of natural seawater splitting.Herein,by DFT calculation,we demonstrated that the interface boundaries between Ni_(2)P and MoO_(2) play an essential role in the selfrelaxation of the Ni-O interfacial bond,effectively modulating a coordination number of intermediates to control independently their adsorption-free energy,thus circumventing the adsorption-energy scaling relation.Following this conceptual model,a well-defined 3D F-doped Ni_(2)P-MoO_(2) heterostructure microrod array was rationally designed via an interfacial engineering strategy toward urea-assisted natural seawater electrolysis.As a result,the F-Ni_(2)P-MoO_(2) exhibits eminently active and durable bifunctional catalysts for both HER and OER in acid,alkaline,and alkaline sea water-based electrolytes.By in-situ analysis,we found that a thin amorphous layer of NiOOH,which is evolved from the Ni_(2)P during anodic reaction,is real catalytic active sites for the OER and UOR processes.Remarkable,such electrode-assembled urea-assisted natural seawater electrolyzer requires low voltages of 1.29 and 1.75 V to drive 10 and600 mA cm^(-2)and demonstrates superior durability by operating continuously for 100 h at 100 mA cm^(-2),beyond commercial Pt/C||RuO_(2) and most previous reports.展开更多
This paper aims to investigate a dam break in a channel with a bend in the presence of several obstacles.To accurately determine the flood zones,it is necessary to take into account many factors such as terrain,reserv...This paper aims to investigate a dam break in a channel with a bend in the presence of several obstacles.To accurately determine the flood zones,it is necessary to take into account many factors such as terrain,reservoir volume.Numerical modeling was used to determine the flood zone.Numerical modeling based on the Navier-Stokes equations with a turbulent k-epsilon RNG model,the Volume of Fluid(VOF)method and the PISO algorithm were used to analyze the flow in a bend channel at an angle of 10 with the obstacles.To verify the numerical model,a test on dam break in the 450 channel was conducted.The simulation results were compared with experimental data and with the numerical data of existing data.Having been convinced of the correctness of the mathematical model,the authors carried out a numerical simulation of the main problem in three versions:without barriers,with one obstacle,with two obstacles.According to the obtained numerical results,it can be noted that irregular landforms held the flow,a decrease in water level and a slower time for water emergence could be seen.Thus,the water flow without an obstacle,with one obstacle and with two obstacles showed 4.2 s,4.4 s and 4.6 s of the time of water appearance,respectively.This time shift can give a certain advantage when conducting various events to evacuate people.展开更多
In the present work,we utilize the approach of the ab initio valence-space in-medium similarity renormalization group(VS-IMSRG)to investigate isospin-symmetry breaking in medium mass nuclei.The adopted nuclear force i...In the present work,we utilize the approach of the ab initio valence-space in-medium similarity renormalization group(VS-IMSRG)to investigate isospin-symmetry breaking in medium mass nuclei.The adopted nuclear force incorporates charge-symmetry and charge-independence breakings.We focus on computing mirror energies of sd-and pf-shell nuclei and discuss the inuence of single-particle states,particularly those with s-wave character,on weakly bound and unbound nuclear states of sd-shell nuclei.展开更多
China’s Olympic delegation at the Paris 2024,with 404 athletes competing in 232 events across 30 sports,clinched 40 gold,27 silver,and 24 bronze medals,marking their best performance at an Olympics held abroad.The su...China’s Olympic delegation at the Paris 2024,with 404 athletes competing in 232 events across 30 sports,clinched 40 gold,27 silver,and 24 bronze medals,marking their best performance at an Olympics held abroad.The success of these athletes across various disciplines demonstrates the country’s efforts to expand its athletic prowess while also marks a new chapter for Chinese sportsmanship on the international stage.展开更多
Making use of the Z2×Z2 symmetry,we could study the structure near multiple S-treaking turning points.In particular,we show that there exist two kinds of singular point path through double S breaking turning poin...Making use of the Z2×Z2 symmetry,we could study the structure near multiple S-treaking turning points.In particular,we show that there exist two kinds of singular point path through double S breaking turning points and triple S bieaking turning points,one ts quadratic turning pornt path and one is quadratic pitch fork bifurcation point path.Some simple regular extended systems to corn pute double and triple S-breaking turning points are proposed.Numerical examples are also展开更多
Smartex,a trailblazing leader in textile industry innovation,was proud to announce its return to ITM 2024,showcasing unparalleled advancements in quality control and production efficiency.Building on the success of pr...Smartex,a trailblazing leader in textile industry innovation,was proud to announce its return to ITM 2024,showcasing unparalleled advancements in quality control and production efficiency.Building on the success of previous exhibitions at ITM 2022 and ITMA Milan 2023,Smartex emerges stronger than ever,presenting its complete Smartex System tailored to transform textile manufacturing.展开更多
大学生科研训练(Student Research Training,SRT)计划是提高大学生科研能力的重要途径之一,也是培养国家理科基地创新性人才的重要举措。为了解决在实施SRT过程中出现的老师与学生交流不足的问题,南京农业大学引入了以Coffee Break...大学生科研训练(Student Research Training,SRT)计划是提高大学生科研能力的重要途径之一,也是培养国家理科基地创新性人才的重要举措。为了解决在实施SRT过程中出现的老师与学生交流不足的问题,南京农业大学引入了以Coffee Break和Seminar为主体的交流模式。经过近四年的实践探索,该模式有力地完善和保障了SRT的顺利实施,大大促进了创新型人才的培养。文章对此进行了详细的阐述。展开更多
文摘Based on comprehensive analyses of seismic and tog data, this study indicates that mainty four widespread angutar to minor angutar unconformities (Tg8, Tg51, Tg5 and Tg3) were formed during the Pateozoic. Through the interpretation of structural unconformities, calcutation of eroded thickness, correction of pataeo-water depth and compaction and compiration of the Earty Paleozoic structural maps, the Earty Paleozoic stope break bert (geomorphologic unit) of the Tarim Basin is subdivided into uptift area, subaqueous uptift area, rift slope break belt, flexure stope break bert (stope bert), depression area and deep basin area. Pataeogeomorphotogy of the Cambrian-Early Ordovician was approximately in EW trend within which three tectonic units inctuding the Tabei Pataeo-uptift, the northern Depressional Belt and the southern Pataeo-uptift developed respectivety and are grouped into two stope break systems namety as the Tabei Pataeo-uptift and the southern Pataeo-uptift. These tectonic units obviousty controt the deposition of isolated platform, open platform, restricted ptatform and deep basin. Influenced by extrusion in the Mid-Late Ordovician, the southern and northern subaqueous uptifts graduat[y etevated and then were eroded. Resuttant[y two slope break systems devetoped, namely as the northern and central Pataeo-uptifts which obviousty controtled the deposition of provenance area, isolated ptatform, mixed continental shelf, slope and basin facies. The intensive extrusion of the Mid-Late Ordovician reads to significant tectonic deformation of the Tarim Basin: large area of uplifting and erosion and development of EW trending anticline and syncline. Deposition of shore, tidal fiat, delta, shallow marine clastics and deep marine facies is obviously controlled by the Tabei, the southern and the Tadong Palaeo-uplifts. Slope break systems control development of stratigraphic unconformity and thus truncation and onlap unconformity zones become favorable areas in a palaeo-uplift and at a palaeo-slope belt for forming important unconformity traps; Whereas slope (slope break) belt along a palaeo-uplift margin is a geomorphologic unit where high-energy sedimentary facies widely develops, such as reef, oolitic sandy clastics or bioclastic limestone beach bar facies, thus litho-structural composite hydrocarbon accumulations usually develop when tectonic condition is suitable. In addition, large-scale palaeo-uplifts are the most favourable areas for hydrocarbon accumulation development.
基金The project supported by the Natural Science Foundation of Zhejiang Province under Grant No. Y604106, the Foundation of New Century 151 Talent Engineering of Zhejiang Province, and the Natural Science Foundation of Zhejiang Lishui University under Grant No. KZ05010 Acknowledgments The authors would like to thank professor Chun-Long Zheng for his fruitful and helpful suggestions.
文摘By means of an improved mapping method and a variable separation method, a series of variable separation solutions including solitary wave solutions, periodic wave solutions and rational function solutions) to the (2+1)-dimensional breaking soliton system is derived. Based on the derived solitary wave excitation, we obtain some special annihilation solitons and chaotic solitons in this short note.
基金supported by the Program for National Defense Science and Technology Foundation Strengtheningthe Youth Foundation of Rocket Force University of Engineering(Grant No.2021QN-B014)。
文摘A submerged cavitation water jet(SCWJ)is an effective method to recycle solid propellant from obsolete solid engines by the breaking method.Solid propellant's breaking modes and mechanical process under SCWJ impact are unclear.This study aims to understand those impact breaking mechanisms.The hydroxyl-terminated polybutadiene(HTPB)propellant was chosen as the research material,and a self-designed test system was used to conduct impact tests at four different working pressures.The high-speed camera characterized crack propagation,and the DIC method calculated strain change during the impact process.Besides,micro and macro fracture morphologies were characterized by scanning electron microscope(SEM)and computed tomography(CT)scanning.The results reveal that the compressive strain concentration region locates right below the nozzle,and the shear strain region distributes symmetrically with the jet axis,which increases to 4% at first 16th ms,the compressive strain rises to 2% and 6% in the axial and transverse direction,respectively.The two tensile cracks formed first at the compression strain concentrate region,and there generate many shear cracks around the tensile cracks,and those shear cracks that develop and aggregate cause the cracks to become wider and cut through the tensile cracks,forming the tensile-shear cracks and the impact parts eventually fail.The HTPB propellant forms a breaking hole shaped conical after impact 10 s.The mass loss increases by 17 times at maximum,with the working pressure increasing by three times.Meanwhile,the damage value of the breaking hole remaining on the surface increases by 7.8 times while 2.9 times in the depth of the breaking hole.The breaking efficiency is closely affected by working pressures.The failure modes of HTPB impacted by SCWJ are classified as tensile crack-dominated and tensile-shear crack-dominated damage mechanisms.
基金Project supported by the Key Program of the National Natural Science Foundation of China (Grant No.60837004)the Key Project of Jiangxi Electric Power Company (Grant Nos.200950801 and 200950802)
文摘This paper investigates the breaking point between fast- and slow-light in a degenerate two-level atomic system, where fast-light can be converted to slow-light arbitrarily on a single transition line by adjusting the strength of the pumping field. An equivalent incoherent pumping rate is introduced in this simplified theoretical model which exploits the dependence of this feature. The experimental observation is presented as evidence of the breaking point where the injected power is about 0.08 mW.
文摘This paper studies the effects of break through state and system rigidity on vibration and noise in blanking, suggests the describtion of the generation state of breakthrough by the unloading gradient obtained from the force stroke curve, discusses the effect of the relation between the unloading gradient and the vibration system rigidity on vibration, and gives the optimal relationship between these two factors to efficiently reduce the vibration, and this conclusion is verified by noise experiments done by using two presses of unequal rigidity to carry out the same blanking.
文摘In the field of automobile manufacture, during the aluminum alloy cutting, chip forming and breaking process are very complicated. It is affected by many facto rs. Automatic machining process can not be carried through if the chip enlaces t he workpiece or the tool. So the chip control and breaking are key technology. P CD tool has many traits, such as high cutting efficiency, machining precision an d wearability. It is desired that it be used for machining coloured metals.The p aper present the study of prediction of chip breaking when PCD Tool cutting alum inum alloy with chip breaker. In the process of cutting, the method of chip brea king is up-curl-dominant chip. Therefore, based on the theory of chip breaking with chip breaker, used the cutting condition of chip breaking, this paper dedu ce the chip breaking mathematical model when cutting aluminum alloy, that is to say, the chip breaker parameters(Angle of chip break,chip groove width, bevel a ngle, the normal rake angle of chip groove, tool cutting edge angle)influence th e critical feed rate. The following conclusion can be made from theoretic analys is. The critical feed rate will decrease when the Angle of chip break and bevel angle and the normal rake angle of chip groove and tool cutting edge angle incre ase. The critical feed rate will increase when chip groove width increase. The e xperimental results are well coincided with the theoretic ones, it is proved tha t the predicting system is correct.
文摘In this work, starting from the (G'/G)-expansion method and a variable separation method, a new non-traveling wave general solutions of the (2+1)-dimensional breaking soliton system are derived. By selecting appropriately the arbitrary functions in the solutions, special soliton-structure excitations and evolutions are studied.
文摘To restore the distribution systems in emergency states with the minimum load shedding, a novel Tabu search approach is put forward. The set of tripped switches is used as candidate solution. Some virtual tripped nodes are defined at the ends of the terminal nodes and by the source nodes. The neighborhood searching is committed by moving a tripped switch to the adjacent node of its upper stream and down stream, respectively. A Tabu list is formed for the tripped switches. The index is to energize as much as possible loads with as less as possible operated times. The electrical limitations and the voltage criterions are used as constrictions. The global aspiration criterion is adopted. An example is given, which shows that the proposed approach is feasible and can deal with complicated indexes.
文摘Adding a U(1) symmetry breaking term √V(λ1a0 + λ1*a0) + √V(λ2b0 + λ2*b0) to Bogoliubov's truncated Hamiltonian HB for a weakly interacting coupled Bose system, by using the mean-field approximation rather than the c-number approximation, we And that, via a Feshbach resonance at zero temperature, the states of the coupled Bose system are generalized SU(1,1) SU(1,1) coherent states. The Bose-Einstein condensation occurs in response to the spontaneous U(1) symmetry breaking.
基金funded by the National Key R&D Program of China (Grant No. 2021YFB3401500)Engineering research 2023-GCKY-001the National Natural Science Foundation of China(Grant Nos. 52004018, 52304119)。
文摘The cavitation cloud impingement of the jet in the rock breaking process was experimentally investigated to reveal the jet erosion mechanism in drilling of petroleum exploitation. Serial erosion tests and flow visualization were performed, where the cavitation cloud motion in the erosion crater was obtained with the designed transparent specimen. Various erosion patterns were identified in the whole erosion process based on the eroded specimen topography. The shallow eroded crater with a shrinking erosion area is generated by the combination of impinging and scattering cavitation clouds. The increase of l_(d) promotes the development of cavitation cloud σ_(c) but reduces the impingement frequency f_(d), suggesting that the jet aggressive ability is enhanced when the balance between σ_(c) and f_(d) is reached. The cavitation cloud motion in the erosion crater was investigated with the transparent specimen. The erosion in the crater at shorter exposure periods T_(e) is generated by the combination of impingement and restricted scattering of cavitation clouds. With the continuous development of the erosion damage, the jet's aggressive ability is diminished due to the erosion expansion on sandstone, where the cavitation clouds impinge on the target and then collapse and vanish without restricted scattering.
基金supported by the National Key Research and Development Program of China(Grant No.2019YFA0308500)the National Natural Science Foundation of China(Grant Nos.62488201,52072401,11888101,12234016,and 12174317)+4 种基金the Chinese Academy of Sciences(Grant No.YSBR-003)the Innovation Program of Quantum Science and Technology(Grant No.2021ZD0302700)the New Cornerstone Science Foundationthe China Postdoctoral Science Foundation(Grant No.2022M723111)the Fellowship of China National Postdoctoral Program for Innovative Talents(Grant No.BX20230358)。
文摘Topologically nontrivial Fe-based superconductors attract extensive attentions due to their ability of hosting Majorana zero modes(MZMs)which could be used for topological quantum computation.Topological defects such as vortex lines are required to generate MZMs.Here,we observe the robust edge states along the surface steps of CaKFe_(4)As_(4).Remarkably,the tunneling spectra show a sharp zero-bias peak(ZBP)with multiple integerquantized states at the step edge under zero magnetic field.We propose that the increasing hole doping around step edges may drive the local superconductivity into a state with possible spontaneous time-reversal symmetry breaking.Consequently,the ZBP can be interpreted as an MZM in an effective vortex in the superconducting topological surface state by proximity to the center of a tri-junction with different superconducting order parameters.Our results provide new insights into the interplay between topology and unconventional superconductivity,and pave a new path to generate MZMs without magnetic field.
基金funded by the National Natural Science Foundation of China(grants 41571054 and 31622015)the National Basic Research Program of China(grant 2014CB954100)+1 种基金Sichuan University(Fundamental Research Funds for the Central Universities,SCU2021D006 and SCU2022D003Institutional Research Funds,2021SCUNL102).
文摘Biogeographical barriers to gene flow are central to plant phylogeography.In East Asia,plant distribution is greatly influenced by two phylogeographic breaks,the Mekong-Salween Divide and Tanaka-Kaiyong Line,however,few studies have investigated how these barriers affect the genetic diversity of species that are distributed across both.Here we used 14 microsatellite loci and four chloroplast DNA fragments to examine genetic diversity and distribution patterns of 49 populations of Populus rotundifolia,a species that spans both the Mekong-Salween Divide and the Tanaka-Kaiyong Line in southwestern China.Demographic and migration hypotheses were tested using coalescent-based approaches.Limited historical gene flow was observed between the western and eastern groups of P.rotundifolia,but substantial flow occurred across both the Mekong-Salween Divide and Tanaka-Kaiyong Line,manifesting in clear admixture and high genetic diversity in the central group.Wind-borne pollen and seeds may have facilitated the dispersal of P.rotundifolia following prevalent northwest winds in the spring.We also found that the Hengduan Mountains,where multiple genetic barriers were detected,acted on the whole as a barrier between the western and eastern groups of P.rotundifolia.Ecological niche modeling suggested that P.rotundifolia has undergone range expansion since the last glacial maximum,and demographic reconstruction indicated an earlier population expansion around 600 Ka.The phylogeographic pattern of P.rotundifolia reflects the interplay of biological traits,wind patterns,barriers,niche differentiation,and Quaternary climate history.This study emphasizes the need for multiple lines of evidence in understanding the Quaternary evolution of plants in topographically complex areas.
基金supported by the Vietnam National University,Ho Chi Minh City (Grant No.TX2024-50-01)partial supported by National Natural Science Foundation of China (Grant No.22209186)。
文摘Urea-assisted natural seawater electrolysis is an emerging technology that is effective for grid-scale carbon-neutral hydrogen mass production yet challenging.Circumventing scaling relations is an effective strategy to break through the bottleneck of natural seawater splitting.Herein,by DFT calculation,we demonstrated that the interface boundaries between Ni_(2)P and MoO_(2) play an essential role in the selfrelaxation of the Ni-O interfacial bond,effectively modulating a coordination number of intermediates to control independently their adsorption-free energy,thus circumventing the adsorption-energy scaling relation.Following this conceptual model,a well-defined 3D F-doped Ni_(2)P-MoO_(2) heterostructure microrod array was rationally designed via an interfacial engineering strategy toward urea-assisted natural seawater electrolysis.As a result,the F-Ni_(2)P-MoO_(2) exhibits eminently active and durable bifunctional catalysts for both HER and OER in acid,alkaline,and alkaline sea water-based electrolytes.By in-situ analysis,we found that a thin amorphous layer of NiOOH,which is evolved from the Ni_(2)P during anodic reaction,is real catalytic active sites for the OER and UOR processes.Remarkable,such electrode-assembled urea-assisted natural seawater electrolyzer requires low voltages of 1.29 and 1.75 V to drive 10 and600 mA cm^(-2)and demonstrates superior durability by operating continuously for 100 h at 100 mA cm^(-2),beyond commercial Pt/C||RuO_(2) and most previous reports.
基金supported by the grant from the Ministry of science and Higher education of the Republic of Kazakhstan(AP23489948).
文摘This paper aims to investigate a dam break in a channel with a bend in the presence of several obstacles.To accurately determine the flood zones,it is necessary to take into account many factors such as terrain,reservoir volume.Numerical modeling was used to determine the flood zone.Numerical modeling based on the Navier-Stokes equations with a turbulent k-epsilon RNG model,the Volume of Fluid(VOF)method and the PISO algorithm were used to analyze the flow in a bend channel at an angle of 10 with the obstacles.To verify the numerical model,a test on dam break in the 450 channel was conducted.The simulation results were compared with experimental data and with the numerical data of existing data.Having been convinced of the correctness of the mathematical model,the authors carried out a numerical simulation of the main problem in three versions:without barriers,with one obstacle,with two obstacles.According to the obtained numerical results,it can be noted that irregular landforms held the flow,a decrease in water level and a slower time for water emergence could be seen.Thus,the water flow without an obstacle,with one obstacle and with two obstacles showed 4.2 s,4.4 s and 4.6 s of the time of water appearance,respectively.This time shift can give a certain advantage when conducting various events to evacuate people.
基金National Natural Science Foundation of China(12205340,12175281,11975282,11921006,11835001,12035001)Gansu Natural Science Foundation(22JR5RA123)Strategic Priority Research Program of Chinese Academy of Sciences(XDB34000000)。
文摘In the present work,we utilize the approach of the ab initio valence-space in-medium similarity renormalization group(VS-IMSRG)to investigate isospin-symmetry breaking in medium mass nuclei.The adopted nuclear force incorporates charge-symmetry and charge-independence breakings.We focus on computing mirror energies of sd-and pf-shell nuclei and discuss the inuence of single-particle states,particularly those with s-wave character,on weakly bound and unbound nuclear states of sd-shell nuclei.
文摘China’s Olympic delegation at the Paris 2024,with 404 athletes competing in 232 events across 30 sports,clinched 40 gold,27 silver,and 24 bronze medals,marking their best performance at an Olympics held abroad.The success of these athletes across various disciplines demonstrates the country’s efforts to expand its athletic prowess while also marks a new chapter for Chinese sportsmanship on the international stage.
基金This work is supported by NSFC amd Slate Major Key Project for Baslc Research
文摘Making use of the Z2×Z2 symmetry,we could study the structure near multiple S-treaking turning points.In particular,we show that there exist two kinds of singular point path through double S breaking turning points and triple S bieaking turning points,one ts quadratic turning pornt path and one is quadratic pitch fork bifurcation point path.Some simple regular extended systems to corn pute double and triple S-breaking turning points are proposed.Numerical examples are also
文摘Smartex,a trailblazing leader in textile industry innovation,was proud to announce its return to ITM 2024,showcasing unparalleled advancements in quality control and production efficiency.Building on the success of previous exhibitions at ITM 2022 and ITMA Milan 2023,Smartex emerges stronger than ever,presenting its complete Smartex System tailored to transform textile manufacturing.
文摘大学生科研训练(Student Research Training,SRT)计划是提高大学生科研能力的重要途径之一,也是培养国家理科基地创新性人才的重要举措。为了解决在实施SRT过程中出现的老师与学生交流不足的问题,南京农业大学引入了以Coffee Break和Seminar为主体的交流模式。经过近四年的实践探索,该模式有力地完善和保障了SRT的顺利实施,大大促进了创新型人才的培养。文章对此进行了详细的阐述。