The expansion of a thick-walled hollow cylinder in soil is of non-self-similar nature that the stress/deformation paths are not the same for different soil material points.As a result,this problem cannot be solved by ...The expansion of a thick-walled hollow cylinder in soil is of non-self-similar nature that the stress/deformation paths are not the same for different soil material points.As a result,this problem cannot be solved by the common self-similar-based similarity techniques.This paper proposes a novel,exact solution for rigorous drained expansion analysis of a hollow cylinder of critical state soils.Considering stress-dependent elastic moduli of soils,new analytical stress and displacement solutions for the nonself-similar problem are developed taking the small strain assumption in the elastic zone.In the plastic zone,the cavity expansion response is formulated into a set of first-order partial differential equations(PDEs)with the combination use of Eulerian and Lagrangian descriptions,and a novel solution algorithm is developed to efficiently solve this complex boundary value problem.The solution is presented in a general form and thus can be useful for a wide range of soils.With the new solution,the non-self-similar nature induced by the finite outer boundary is clearly demonstrated and highlighted,which is found to be greatly different to the behaviour of cavity expansion in infinite soil mass.The present solution may serve as a benchmark for verifying the performance of advanced numerical techniques with critical state soil models and be used to capture the finite boundary effect for pressuremeter tests in small-sized calibration chambers.展开更多
We present a stable valley photonic crystal(VPC)unit cell with C_(3v)symmetric quasi-ring-shaped dielectric columns and realize its topological phase transition by breaking mirror symmetry.Based on this unit cell stru...We present a stable valley photonic crystal(VPC)unit cell with C_(3v)symmetric quasi-ring-shaped dielectric columns and realize its topological phase transition by breaking mirror symmetry.Based on this unit cell structure,topological edge states(TESs)and topological corner states(TCSs)are realized.We obtain a new type of wave transmission mode based on photonic crystal zipper-like boundaries and apply it to a beam splitter assembled from rectangular photonic crystals(PCs).The constructed beam splitter structure is compact and possesses frequency separation functions.In addition,we construct a box-shaped triangular PC structures with zipper-like boundaries and discover phenomena of TCSs in the corners,comparing its corner states with those formed by other boundaries.Based on this,we explore the regularities of the electric field patterns of TESs and TCSs,explain the connection between the characteristic frequencies and locality of TCSs,which helps better control photons and ensures low power consumption of the system.展开更多
Critical states in disordered systems,fascinating and subtle eigenstates,have attracted a lot of research interests.However,the nature of critical states is difficult to describe quantitatively,and in general,it canno...Critical states in disordered systems,fascinating and subtle eigenstates,have attracted a lot of research interests.However,the nature of critical states is difficult to describe quantitatively,and in general,it cannot predict a system that hosts the critical state.We propose an explicit criterion whereby the Lyapunov exponent of the critical state should be 0 simultaneously in dual spaces,namely the Lyapunov exponent remains invariant under the Fourier transform.With this criterion,we can exactly predict a one-dimensional quasiperiodic model which is not of self-duality,but hosts a large number of critical states.Then,we perform numerical verification of the theoretical prediction and display the self-similarity of the critical state.Due to computational complexity,calculations are not performed for higher dimensional models.However,since the description of extended and localized states by the Lyapunov exponent is universal and dimensionless,utilizing the Lyapunov exponent of dual spaces to describe critical states should also be universal.Finally,we conjecture that some kind of connection exists between the invariance of the Lyapunov exponent and conformal invariance,which can promote the research of critical phenomena.展开更多
Background: In recent times, there has been an increase in the number of Lassa fever cases resulting from the several episodes of Lassa fever epidemics ravaging Nigeria and other West African countries. The presence o...Background: In recent times, there has been an increase in the number of Lassa fever cases resulting from the several episodes of Lassa fever epidemics ravaging Nigeria and other West African countries. The presence of Lassa virus in rodents other than the major reservoir (Mastomys natalensis) has been a public health concern as to the actual burden of the disease. It is therefore of a public health necessity to explore the LASV RNA habouring potential of several species of rodents in endemic as well as non-endemic areas for proper prevention of emergence of outbreaks in non-endemic areas. Objectives: The aim of this study was to detect the presence of LASV RNA in different species of rodents in Ikorodu, Lagos state and Abeokuta, Ogun state. Methods: A total of ninety one (91) rodents were captured from Ikorodu, Lagos State (61 rodents) and Abeokuta, Ogun State (30 rodents), euthanized, bled, and plasma obtained for the detection of LASV RNA by Reverse Transcriptase Polymerase Chain Reaction. Results: A total of 91 rodents consisting of 77 Rattus rattus and 14 Crocidura spp. The S segment of LASV RNA was not in any of the 91 rodents’ plasma samples. Conclusion: The rodents captured within the rural communities of Ikorodu, Lagos State and Abeokuta, Ogun State were found not to habour the LASV RNA. This study is limited by the relatively small sample size. Similar studies should be encouraged both in endemic and non-endemic areas in order to understand the actual burden of Lassa fever as well as put into check future epidemics.展开更多
The study comparatively analysed the socioeconomic characteristics and digital literacy level of Agricultural Extension personnel (AEP) in Ebonyi and Imo States, South-East, Nigeria. The specific objectives were to de...The study comparatively analysed the socioeconomic characteristics and digital literacy level of Agricultural Extension personnel (AEP) in Ebonyi and Imo States, South-East, Nigeria. The specific objectives were to describe the socioeconomic characteristics of agricultural extension personnel in Ebonyi and Imo States, and to ascertain the digital literacy level of AEP in the studied states. Purposive sampling technique was used to select 312 Agricultural Extension personnel (132 from Ebonyi State Agricultural Development Program and 180 from Imo State Agricultural Development Program) for the study. Data were collected through the use of validated and structured questionnaire, and administered through the help of well-trained enumerators. Data were analysed using simple descriptive statistical tools such as percentages mean score, standard deviation and weighted mean. Findings indicated that they were more male in the both States (55.3% and 57.8%) for Ebonyi and Imo State respectively and that the average age of AEP in Ebonyi and Imo States were 44.7 years and 49.2 years respectively. It was further revealed that the majority (77.3% and 82.8%) had B.Sc./HND as their highest academic qualifications, belonged to professional organisations (62.1% and 75%), and were earning an average monthly income of N58,798 and N62,648 for Ebonyi and Imo State respectively. Also, it was revealed that their mean years of service were 12.4 years and 13.4 years for Ebonyi and Imo State respectively. Almost all of them (87.9% and 95.0%) own a smartphone, had access to the internet (80.3% and 90.0%), but do not own a laptop/ipad (82.6% and 72.8%) for Ebon-yi and Imo State respectively. Results further revealed that Agricultural extension personnel in both Ebonyi and Imo State respectively had low digital literacy level ( = 2.41 and 2.32). The study concluded that AEP in Ebonyi and Imo State respectively had similar socioeconomic characteristics and low level of digital literacy. The study recommended that the management of ADPs in both Ebonyi and Imo State should ensure the training of AEP in digital skills to enhance their digital literacy level to enable them use digital technologies in their work.展开更多
The long-term storage of phosphate tailings will occupy a large amount of land,pollute soil and groundwater,thus,it is crucial to achieve the harmless disposal of phosphate tailings.In this study,high-performance geop...The long-term storage of phosphate tailings will occupy a large amount of land,pollute soil and groundwater,thus,it is crucial to achieve the harmless disposal of phosphate tailings.In this study,high-performance geopolymers with compressive strength of 38.8 MPa were prepared by using phosphate tailings as the main raw material,fly ash as the active silicon-aluminum material,and water glass as the alkaline activator.The solid content of phosphate tailings and fly ash was 60% and 40%,respectively,and the water-cement ratio was 0.22.The results of XRD,FTIR,SEM-EDS and XPS show that the reactivity of phosphate tailings with alkaline activator is weak,and the silicon-aluminum material can react with alkaline activator to form zeolite and gel,and encapsulate/cover the phosphate tailings to form a dense phosphate tailings-based geopolymer.During the formation of geopolymers,part of the aluminum-oxygen tetrahedron replaced the silicon-oxygen tetrahedron,causing the polycondensation reaction between geopolymers and increasing the strength of geopolymers.The leaching toxicity test results show that the geopolymer has a good solid sealing effect on heavy metal ions.The preparation of geopolymer from phosphate tailings is an important way to alleviate the storage pressure and realize the resource utilization of phosphate tailings.展开更多
Numerical simulation is employed to investigate the initial state of avalanche in polydisperse particle systems.Nucleation and propagation processes are illustrated for pentadisperse and triadisperse particle systems,...Numerical simulation is employed to investigate the initial state of avalanche in polydisperse particle systems.Nucleation and propagation processes are illustrated for pentadisperse and triadisperse particle systems,respectively.In these processes,particles involved in the avalanche grow slowly in the early stage and explosively in the later stage,which is clearly different from the continuous and steady growth trend in the monodisperse system.By examining the avalanche propagation,the number growth of particles involved in the avalanche and the slope of the number growth,the initial state can be divided into three stages:T1(nucleation stage),T2(propagation stage),T3(overall avalanche stage).We focus on the characteristics of the avalanche in the T2 stage,and find that propagation distances increase almost linearly in both axial and radial directions in polydisperse systems.We also consider the distribution characteristics of the average coordination number and average velocity for the moving particles.The results support that the polydisperse particle systems are more stable in the T2 stage.展开更多
Ammonia(NH3)serves as a critical component in the fertilizer industry and fume gas denitrification.However,the conventional NH3production process,namely the Haber-Bosch process,leads to considerable energy consumption...Ammonia(NH3)serves as a critical component in the fertilizer industry and fume gas denitrification.However,the conventional NH3production process,namely the Haber-Bosch process,leads to considerable energy consumption and waste gas emissions.To address this,electrocatalytic nitric oxide reduction reaction(NORR)has emerged as a promising strategy to bridge NH3consumption to NH3production,harnessing renewable electricity for a sustainable future.Copper(Cu)stands out as a prominent electrocatalyst for NO reduction,given its exceptional NH3yield and selectivity.However,a crucial aspect that remains insufficiently explored is the effects of morphology and valence states of Cu on the NORR performance.In this investigation,we synthesized CuO nanowires(CuO-NF)and Cu nanocubes(Cu-NF)as cathodes through an in situ growth method.Remarkably,CuO-NF exhibited an impressive NH3yield of 0.50±0.02 mg cm^(-2)h^(-1)at-0.6 V vs.reversible hydrogen electrode(RHE)with faradaic efficiency of29,68%±1,35%,surpassing that of Cu-NF(0.17±0.01 mg cm^(-2)h^(-1),16.18%±1.40%).Throughout the electroreduction process,secondary cubes were generated on the CuO-NF surface,preserving their nanosheet cluster morphology,sustained by an abundant supply of subsurface oxygen(s-O)even after an extended duration of 10 h,until s-O depletion ensued.Conversely,Cu-NF exhibited inadequate s-O content,leading to rapid crystal collapse within the same timeframe.The distinctive current-potential relationship,akin to a volcano-type curve,was attributed to distinct NO hydrogenation mechanisms.Further Tafel analysis revealed the exchange current density(i0)and standard heterogeneous rate constant(k0)for CuO-NF,yielding 3.44×10^(-6)A cm^(-2)and 3.77×10^(-6)cm^(-2)s^(-1)when NORR was driven by overpotentials.These findings revealed the potential of CuO-NF for NO reduction and provided insights into the intricate interplay between crystal morphology,valence states,and electrochemical performance.展开更多
The SiS molecule,which plays a significant role in space,has attracted a great deal of attention for many years.Due to complex interactions among its low-lying electronic states,precise information regarding the molec...The SiS molecule,which plays a significant role in space,has attracted a great deal of attention for many years.Due to complex interactions among its low-lying electronic states,precise information regarding the molecular structure of SiS is limited.To obtain accurate information about the structure of its excited states,the high-precision multireference configuration interaction(MRCI)method has been utilized.This method is used to calculate the potential energy curves(PECs)of the 18Λ–S states corresponding to the lowest dissociation limit of SiS.The core–valence correlation effect,Davidson’s correction and the scalar relativistic effect are also included to guarantee the precision of the MRCI calculation.Based on the calculated PECs,the spectroscopic constants of quasi-bound and bound electronic states are calculated and they are in accordance with previous experimental results.The transition dipole moments(TDMs)and dipole moments(DMs)are determined by the MRCI method.In addition,the abrupt variations of the DMs for the 1^(5)Σ^(+)and 2^(5)Σ^(+)states at the avoided crossing point are attributed to the variation of the electronic configuration.The opacity of SiS at a pressure of 100 atms is presented across a series of temperatures.With increasing temperature,the expanding population of excited states blurs the band boundaries.展开更多
We investigated the one-dimensional diamond ladder in the momentum lattice platform. By inducing multiple twoand four-photon Bragg scatterings among specific momentum states, we achieved a flat band system based on th...We investigated the one-dimensional diamond ladder in the momentum lattice platform. By inducing multiple twoand four-photon Bragg scatterings among specific momentum states, we achieved a flat band system based on the diamond model, precisely controlling the coupling strength and phase between individual lattice sites. Utilizing two lattice sites couplings, we generated a compact localized state associated with the flat band, which remained localized throughout the entire time evolution. We successfully realized the continuous shift of flat bands by adjusting the corresponding nearest neighbor hopping strength, enabling us to observe the complete localization process. This opens avenues for further exploration of more complex properties within flat-band systems, including investigating the robustness of flat-band localized states in disordered flat-band systems and exploring many-body localization in interacting flat-band systems.展开更多
Background: Nigeria, a nation grappling with rapid population growth, economic intricacies, and complex healthcare challenges, particularly in Lagos State, the economic hub and most populous state, faces the challenge...Background: Nigeria, a nation grappling with rapid population growth, economic intricacies, and complex healthcare challenges, particularly in Lagos State, the economic hub and most populous state, faces the challenge of ensuring quality healthcare access. The overview of the effect of quality improvement initiatives in this paper focuses on private healthcare providers in Lagos State, Nigeria. The study assesses the impact of donor-funded quality improvement projects on these private healthcare facilities. It explores the level of participation, perceived support, and tangible effects of the initiatives on healthcare delivery within private healthcare facilities. It also examines how these initiatives influence patient inflow and facility ratings, and bring about additional benefits and improvements, provides insights into the challenges faced by private healthcare providers in implementing quality improvement projects and elicits recommendations for improving the effectiveness of such initiatives. Methods: Qualitative research design was employed for in-depth exploration, utilizing semi-structured interviews. Private healthcare providers in Lagos involved in the SP4FP Quality Improvement Project were purposively sampled for diversity. Face-to-face interviews elicited insights into participation, perceived support, and project effects. Questions covered participation levels, support perception, changes observed, challenges faced, and recommendations. Thematic analysis identified recurring themes from interview transcripts. Adherence to ethical guidelines ensured participant confidentiality and informed consent. Results: Respondents affirmed active involvement in the SP4FP Quality Improvement Project, echoing literature emphasizing private-sector collaboration with the public sector. While acknowledging positive influences on facility ratings, respondents highlighted challenges within the broader Nigerian healthcare landscape affecting patient numbers. Respondents cited tangible improvements, particularly in staff management and patient care processes, validating the positive influence of quality improvement projects. Financial constraints emerged as a significant challenge, aligning with existing literature emphasizing the pragmatic difficulties faced by private healthcare providers. Conclusions: This study illuminates the complex landscape of private healthcare provision in Lagos State, emphasizing the positive impact of donor-funded quality improvement projects. The findings provide nuanced insights, guiding policymakers, healthcare managers, and practitioners toward collaborative, sustainable improvements. As Nigeria progresses, these lessons will be crucial in shaping healthcare policies prioritizing population well-being.展开更多
We study the chiral bound states in a coupled-resonator array with staggered hopping strengths,which interacts with a two-level small atom through a single coupling point or two adjacent ones.In addition to the two ty...We study the chiral bound states in a coupled-resonator array with staggered hopping strengths,which interacts with a two-level small atom through a single coupling point or two adjacent ones.In addition to the two typical bound states found above and below the energy bands,this system presents an extraordinary chiral bound state located within the energy gap.We use the chirality to quantify the breaking of the mirror symmetry.We find that the chirality value undergoes continuous changes by tuning the coupling strengths.The preferred direction of the chirality is controlled not only by the competition between the intracell and the intercell hoppings in the coupled-resonator array,but also by the coherence between the two coupling points.In the case with one coupling point,the chirality values varies monotonously with difference between the intracell hopping and the intercell hoppings.While in the case with two coupling points,due to the coherence between the two coupling points the perfect chiral states can be obtained.展开更多
Information about electronic excited states of molecular anions plays an important role in investigating electron attachment and detachment processes.Here we present a high-level theoretical study of the electronic st...Information about electronic excited states of molecular anions plays an important role in investigating electron attachment and detachment processes.Here we present a high-level theoretical study of the electronic structures of 12 alkali-metal-containing diatomic anions MX-(MX = LiH,LiF,LiCl,NaF,NaCl,NaBr,RbCl,KCl,KBr,RbI,KI and CsI).The equation-of-motion electron-attachment coupled-cluster singles and doubles(EOM-EA-CCSD) method is used to calculate the electron binding energies(EBEs) of 10 electronic excited states of each of the 12 molecule anions.With addition of different s-/p-/d-type diffusion functions in the basis set,we have identified possible excited dipole bound states(DBSs) of each anion.With the investigation of EBEs on the 12 MXs with dipole moment(DM) up to 12.1 D,we evaluate the dependence of the number of anionic excited DBSs on molecular DM.The results indicate that there are at least two or three DBSs of anions with a molecular DM larger than 7 D and a molecule with DM > 10 D can sustain a π-DBS of the anion.Our study has some implications for the excited DBS electronic states of alkali-metal-containing diatomic molecules.展开更多
Plants play an essential role in matter and energy transformations and are key messengers in the carbon and energy cycle. Net primary productivity (NPP) reflects the capability of plants to transform solar energy into...Plants play an essential role in matter and energy transformations and are key messengers in the carbon and energy cycle. Net primary productivity (NPP) reflects the capability of plants to transform solar energy into photosynthesis. It is very sensible for factors affecting on vegetation variability such as climate, soils, plant characteristics and human activities. So, it can be used as an indicator of actual and potential trend of vegetation. In this study we used the actual NPP which was derived from MODIS to assess the response of NPP to climate variables in Gadarif State, from 2000 to 2010. The correlations between NPP and climate variables (temperature and precipitation) are calculated using Pearson’s Correlation Coefficient and ordinary least squares regression. The main results show the following 1) the correlation Coefficient between NPP and mean annual temperature is Somewhat negative for Feshaga, Rahd, Gadarif and Galabat areas and weakly negative in Faw area;2) the correlation Coefficient between NPP and annual total precipitation is weakly negative in Faw, Rahd and Galabat areas and somewhat negative in Galabat and Rahd areas. This study demonstrated that the correlation analysis between NPP and climate variables (precipitation and temperature) gives reliably result of NPP responses to climate variables that is clearly in a very large scale of study area.展开更多
We revisited the vortex states of 2H-NbSe_(2) towards zero fields by a low-temperature scanning tunneling microscope.Fine structures of the anisotropic vortex states were distinguished, one is a spatially non-splittin...We revisited the vortex states of 2H-NbSe_(2) towards zero fields by a low-temperature scanning tunneling microscope.Fine structures of the anisotropic vortex states were distinguished, one is a spatially non-splitting zero bias peak, and the other is an in-gap conductance anomaly resembling evolved crossing features around the center of the three nearest vortices.Both of them distribute solely along the next nearest neighboring direction of the vortex lattice and become unresolved in much higher magnetic fields, implying an important role played by the vortex–vortex interactions. To clarify these issues,we have studied the intrinsic vortex states of the isolated trapped vortex in zero fields at 0.45 K. It is concluded that the anisotropic zero bias peak is attributed to the superconducting gap anisotropy, and the spatially evolved crossing features are related to the vortex–vortex interaction. The vortex core size under the zero-field limit is determined. These results provide a paradigm for studying the inherent vortex states of type-II superconductors especially based on an isolated vortex.展开更多
We explore the entanglement features of pure symmetric N-qubit states characterized by N-distinct spinors with a particular focus on the Greenberger-Horne-Zeilinger (GHZ) states and , an equal superposition of W and o...We explore the entanglement features of pure symmetric N-qubit states characterized by N-distinct spinors with a particular focus on the Greenberger-Horne-Zeilinger (GHZ) states and , an equal superposition of W and obverse W states. Along with a comparison of pairwise entanglement and monogamy properties, we explore the geometric information contained in them by constructing their canonical steering ellipsoids. We obtain the volume monogamy relations satisfied by states as a function of number of qubits and compare with the maximal monogamy property of GHZ states.展开更多
We investigate the nonlocal transport modulated by Coulomb interactions in devices comprising two interacting Majorana wires,where both nanowires are in proximity to a mesoscopic superconducting(SC)island.Each Majoran...We investigate the nonlocal transport modulated by Coulomb interactions in devices comprising two interacting Majorana wires,where both nanowires are in proximity to a mesoscopic superconducting(SC)island.Each Majorana bound state(MBS)is coupled to one lead via a quantum dot with resonant levels.In this device,the nonlocal correlations can be induced in the absence of Majorana energy splitting.We find that the negative differential conductance and giant current noise cross correlation could be induced,due to the interplay between nonlocality of MBSs and dynamical Coulomb blockade effect.This feature may provide a signature for the existence of the MBSs.展开更多
1-hexene aromatization is a promising technology to convert excess olefin in fluid catalytic cracking(FCC)gasoline to high-value benzene(B),toluene(T),and xylene.Besides,the increasing market demand of xylene has put ...1-hexene aromatization is a promising technology to convert excess olefin in fluid catalytic cracking(FCC)gasoline to high-value benzene(B),toluene(T),and xylene.Besides,the increasing market demand of xylene has put forward higher requirements for new generation of catalyst.For increasing xylene yield in 1-hexene aromatization,the effect of mesopore structure and spatial distribution on product distribution and Zn loading was studied.Catalysts with different mesopore spatial distribution were prepared by post-treatment of parent HZSM-5 zeolite,including NaOH treatment,tetra-propylammonium hydroxide(TPAOH)treatment,and recrystallization.It was found the evenly distributed mesopore mainly prolongs the catalyst lifetime by enhancing diffusion properties but reduces the aromatics selectivity,as a result of damage of micropores close to the catalyst surface.While the selectivity of high-value xylene can be highly promoted when the mesopore is mainly distributed interior the catalyst.Besides,the state of loaded Zn was also affected by mesopores spatial distribution.On the optimized catalyst,the xylene selectivity was enhanced by 12.4%compared with conventional Zn-loaded parent HZSM-5 catalyst at conversion over 99%.It was attributed to the synergy effect of mesopores spatial distribution and optimized acid properties.This work reveals the role of mesopores in different spatial positions of 1-hexene aromatization catalysts in the reaction process and the influence on metal distribution,as well as their synergistic effect two on the improvement of xylene selectivity,which can improve our understanding of catalyst pore structure and be helpful for the rational design of high-efficient catalyst.展开更多
The high entropy alloys(HEAs)are the newly developed high-performance materials that have gained significant importance in defence,nuclear and aerospace sector due to their superior mechanical properties,heat resistan...The high entropy alloys(HEAs)are the newly developed high-performance materials that have gained significant importance in defence,nuclear and aerospace sector due to their superior mechanical properties,heat resistance,high temperature strength and corrosion resistance.These alloys are manufactured by the equal mixing or larger proportions of five or more alloying elements.HEAs exhibit superior mechanical performance compared to traditional engineering alloys because of the extensive alloying composition and higher entropy of mixing.Solid state welding(SSW)techniques such as friction stir welding(FSW),rotary friction welding(RFW),diffusion bonding(DB)and explosive welding(EW)have been efficiently deployed for improving the microstructural integrity and mechanical properties of welded HEA joints.The HEA interlayers revealed greater potential in supressing the formation of deleterious intermetallic phases and maximizing the mechanical properties of HEAs joints.The similar and dissimilar joining of HEAs has been manifested to be viable for HEA systems which further expands their industrial applications.Thus,the main objective of this review paper is to present a critical review of current state of research,challenges and opportunities and main directions in SSW of HEAs mainly CoCrFeNiMn and Al_xCoCrFeNi alloys.The state of the art of problems,progress and future outlook in SSW of HEAs are critically reviewed by considering the formation of phases,microstructural evolution and mechanical properties of HEAs joints.展开更多
Assessment of past-climate simulations of regional climate models(RCMs)is important for understanding the reliability of RCMs when used to project future regional climate.Here,we assess the performance and discuss pos...Assessment of past-climate simulations of regional climate models(RCMs)is important for understanding the reliability of RCMs when used to project future regional climate.Here,we assess the performance and discuss possible causes of biases in a WRF-based RCM with a grid spacing of 50 km,named WRFG,from the North American Regional Climate Change Assessment Program(NARCCAP)in simulating wet season precipitation over the Central United States for a period when observational data are available.The RCM reproduces key features of the precipitation distribution characteristics during late spring to early summer,although it tends to underestimate the magnitude of precipitation.This dry bias is partially due to the model’s lack of skill in simulating nocturnal precipitation related to the lack of eastward propagating convective systems in the simulation.Inaccuracy in reproducing large-scale circulation and environmental conditions is another contributing factor.The too weak simulated pressure gradient between the Rocky Mountains and the Gulf of Mexico results in weaker southerly winds in between,leading to a reduction of warm moist air transport from the Gulf to the Central Great Plains.The simulated low-level horizontal convergence fields are less favorable for upward motion than in the NARR and hence,for the development of moist convection as well.Therefore,a careful examination of an RCM’s deficiencies and the identification of the source of errors are important when using the RCM to project precipitation changes in future climate scenarios.展开更多
基金funding support from the National Key Research and Development Program of China(Grant No.2023YFB2604004)the National Natural Science Foundation of China(Grant No.52108374)the“Taishan”Scholar Program of Shandong Province,China(Grant No.tsqn201909016)。
文摘The expansion of a thick-walled hollow cylinder in soil is of non-self-similar nature that the stress/deformation paths are not the same for different soil material points.As a result,this problem cannot be solved by the common self-similar-based similarity techniques.This paper proposes a novel,exact solution for rigorous drained expansion analysis of a hollow cylinder of critical state soils.Considering stress-dependent elastic moduli of soils,new analytical stress and displacement solutions for the nonself-similar problem are developed taking the small strain assumption in the elastic zone.In the plastic zone,the cavity expansion response is formulated into a set of first-order partial differential equations(PDEs)with the combination use of Eulerian and Lagrangian descriptions,and a novel solution algorithm is developed to efficiently solve this complex boundary value problem.The solution is presented in a general form and thus can be useful for a wide range of soils.With the new solution,the non-self-similar nature induced by the finite outer boundary is clearly demonstrated and highlighted,which is found to be greatly different to the behaviour of cavity expansion in infinite soil mass.The present solution may serve as a benchmark for verifying the performance of advanced numerical techniques with critical state soil models and be used to capture the finite boundary effect for pressuremeter tests in small-sized calibration chambers.
基金Project supported by the Suzhou Basic Research Project (Grant No.SJC2023003)Suzhou City University National Project Pre-research Project (Grant No.2023SGY014)。
文摘We present a stable valley photonic crystal(VPC)unit cell with C_(3v)symmetric quasi-ring-shaped dielectric columns and realize its topological phase transition by breaking mirror symmetry.Based on this unit cell structure,topological edge states(TESs)and topological corner states(TCSs)are realized.We obtain a new type of wave transmission mode based on photonic crystal zipper-like boundaries and apply it to a beam splitter assembled from rectangular photonic crystals(PCs).The constructed beam splitter structure is compact and possesses frequency separation functions.In addition,we construct a box-shaped triangular PC structures with zipper-like boundaries and discover phenomena of TCSs in the corners,comparing its corner states with those formed by other boundaries.Based on this,we explore the regularities of the electric field patterns of TESs and TCSs,explain the connection between the characteristic frequencies and locality of TCSs,which helps better control photons and ensures low power consumption of the system.
基金supported by the Natural Science Foundation of Jiangsu Province(Grant No.BK20200737)the Natural Science Foundation of Nanjing University of Posts and Telecommunications(Grant No.NY223109)+1 种基金the Innovation Research Project of Jiangsu Province(Grant No.JSSCBS20210521)the China Postdoctoral Science Foundation(Grant No.2022M721693)。
文摘Critical states in disordered systems,fascinating and subtle eigenstates,have attracted a lot of research interests.However,the nature of critical states is difficult to describe quantitatively,and in general,it cannot predict a system that hosts the critical state.We propose an explicit criterion whereby the Lyapunov exponent of the critical state should be 0 simultaneously in dual spaces,namely the Lyapunov exponent remains invariant under the Fourier transform.With this criterion,we can exactly predict a one-dimensional quasiperiodic model which is not of self-duality,but hosts a large number of critical states.Then,we perform numerical verification of the theoretical prediction and display the self-similarity of the critical state.Due to computational complexity,calculations are not performed for higher dimensional models.However,since the description of extended and localized states by the Lyapunov exponent is universal and dimensionless,utilizing the Lyapunov exponent of dual spaces to describe critical states should also be universal.Finally,we conjecture that some kind of connection exists between the invariance of the Lyapunov exponent and conformal invariance,which can promote the research of critical phenomena.
文摘Background: In recent times, there has been an increase in the number of Lassa fever cases resulting from the several episodes of Lassa fever epidemics ravaging Nigeria and other West African countries. The presence of Lassa virus in rodents other than the major reservoir (Mastomys natalensis) has been a public health concern as to the actual burden of the disease. It is therefore of a public health necessity to explore the LASV RNA habouring potential of several species of rodents in endemic as well as non-endemic areas for proper prevention of emergence of outbreaks in non-endemic areas. Objectives: The aim of this study was to detect the presence of LASV RNA in different species of rodents in Ikorodu, Lagos state and Abeokuta, Ogun state. Methods: A total of ninety one (91) rodents were captured from Ikorodu, Lagos State (61 rodents) and Abeokuta, Ogun State (30 rodents), euthanized, bled, and plasma obtained for the detection of LASV RNA by Reverse Transcriptase Polymerase Chain Reaction. Results: A total of 91 rodents consisting of 77 Rattus rattus and 14 Crocidura spp. The S segment of LASV RNA was not in any of the 91 rodents’ plasma samples. Conclusion: The rodents captured within the rural communities of Ikorodu, Lagos State and Abeokuta, Ogun State were found not to habour the LASV RNA. This study is limited by the relatively small sample size. Similar studies should be encouraged both in endemic and non-endemic areas in order to understand the actual burden of Lassa fever as well as put into check future epidemics.
文摘The study comparatively analysed the socioeconomic characteristics and digital literacy level of Agricultural Extension personnel (AEP) in Ebonyi and Imo States, South-East, Nigeria. The specific objectives were to describe the socioeconomic characteristics of agricultural extension personnel in Ebonyi and Imo States, and to ascertain the digital literacy level of AEP in the studied states. Purposive sampling technique was used to select 312 Agricultural Extension personnel (132 from Ebonyi State Agricultural Development Program and 180 from Imo State Agricultural Development Program) for the study. Data were collected through the use of validated and structured questionnaire, and administered through the help of well-trained enumerators. Data were analysed using simple descriptive statistical tools such as percentages mean score, standard deviation and weighted mean. Findings indicated that they were more male in the both States (55.3% and 57.8%) for Ebonyi and Imo State respectively and that the average age of AEP in Ebonyi and Imo States were 44.7 years and 49.2 years respectively. It was further revealed that the majority (77.3% and 82.8%) had B.Sc./HND as their highest academic qualifications, belonged to professional organisations (62.1% and 75%), and were earning an average monthly income of N58,798 and N62,648 for Ebonyi and Imo State respectively. Also, it was revealed that their mean years of service were 12.4 years and 13.4 years for Ebonyi and Imo State respectively. Almost all of them (87.9% and 95.0%) own a smartphone, had access to the internet (80.3% and 90.0%), but do not own a laptop/ipad (82.6% and 72.8%) for Ebon-yi and Imo State respectively. Results further revealed that Agricultural extension personnel in both Ebonyi and Imo State respectively had low digital literacy level ( = 2.41 and 2.32). The study concluded that AEP in Ebonyi and Imo State respectively had similar socioeconomic characteristics and low level of digital literacy. The study recommended that the management of ADPs in both Ebonyi and Imo State should ensure the training of AEP in digital skills to enhance their digital literacy level to enable them use digital technologies in their work.
基金Project(202202AG050010)supported by the Yunnan Major Scientific and Technological Projects,ChinaProject(202103AA080007)supported by the Key R&D Project of Science and Technology Department of Yunnan Province,ChinaProject(NECP2023-06)supported by the Open Project Fund of National Engineering and Technology Research Center for Development&Utilization of Phosphorous Resources,China。
文摘The long-term storage of phosphate tailings will occupy a large amount of land,pollute soil and groundwater,thus,it is crucial to achieve the harmless disposal of phosphate tailings.In this study,high-performance geopolymers with compressive strength of 38.8 MPa were prepared by using phosphate tailings as the main raw material,fly ash as the active silicon-aluminum material,and water glass as the alkaline activator.The solid content of phosphate tailings and fly ash was 60% and 40%,respectively,and the water-cement ratio was 0.22.The results of XRD,FTIR,SEM-EDS and XPS show that the reactivity of phosphate tailings with alkaline activator is weak,and the silicon-aluminum material can react with alkaline activator to form zeolite and gel,and encapsulate/cover the phosphate tailings to form a dense phosphate tailings-based geopolymer.During the formation of geopolymers,part of the aluminum-oxygen tetrahedron replaced the silicon-oxygen tetrahedron,causing the polycondensation reaction between geopolymers and increasing the strength of geopolymers.The leaching toxicity test results show that the geopolymer has a good solid sealing effect on heavy metal ions.The preparation of geopolymer from phosphate tailings is an important way to alleviate the storage pressure and realize the resource utilization of phosphate tailings.
基金Project supported by the Qingdao National Laboratory for Marine Science and Technology(Grant No.2015ASKJ01)the National Natural Science Foundation of China(Grant Nos.11972212,12072200,and 12002213).
文摘Numerical simulation is employed to investigate the initial state of avalanche in polydisperse particle systems.Nucleation and propagation processes are illustrated for pentadisperse and triadisperse particle systems,respectively.In these processes,particles involved in the avalanche grow slowly in the early stage and explosively in the later stage,which is clearly different from the continuous and steady growth trend in the monodisperse system.By examining the avalanche propagation,the number growth of particles involved in the avalanche and the slope of the number growth,the initial state can be divided into three stages:T1(nucleation stage),T2(propagation stage),T3(overall avalanche stage).We focus on the characteristics of the avalanche in the T2 stage,and find that propagation distances increase almost linearly in both axial and radial directions in polydisperse systems.We also consider the distribution characteristics of the average coordination number and average velocity for the moving particles.The results support that the polydisperse particle systems are more stable in the T2 stage.
基金supported by the Fundamental Research Funds for the Central Universities(FRF-EYIT-23-07)。
文摘Ammonia(NH3)serves as a critical component in the fertilizer industry and fume gas denitrification.However,the conventional NH3production process,namely the Haber-Bosch process,leads to considerable energy consumption and waste gas emissions.To address this,electrocatalytic nitric oxide reduction reaction(NORR)has emerged as a promising strategy to bridge NH3consumption to NH3production,harnessing renewable electricity for a sustainable future.Copper(Cu)stands out as a prominent electrocatalyst for NO reduction,given its exceptional NH3yield and selectivity.However,a crucial aspect that remains insufficiently explored is the effects of morphology and valence states of Cu on the NORR performance.In this investigation,we synthesized CuO nanowires(CuO-NF)and Cu nanocubes(Cu-NF)as cathodes through an in situ growth method.Remarkably,CuO-NF exhibited an impressive NH3yield of 0.50±0.02 mg cm^(-2)h^(-1)at-0.6 V vs.reversible hydrogen electrode(RHE)with faradaic efficiency of29,68%±1,35%,surpassing that of Cu-NF(0.17±0.01 mg cm^(-2)h^(-1),16.18%±1.40%).Throughout the electroreduction process,secondary cubes were generated on the CuO-NF surface,preserving their nanosheet cluster morphology,sustained by an abundant supply of subsurface oxygen(s-O)even after an extended duration of 10 h,until s-O depletion ensued.Conversely,Cu-NF exhibited inadequate s-O content,leading to rapid crystal collapse within the same timeframe.The distinctive current-potential relationship,akin to a volcano-type curve,was attributed to distinct NO hydrogenation mechanisms.Further Tafel analysis revealed the exchange current density(i0)and standard heterogeneous rate constant(k0)for CuO-NF,yielding 3.44×10^(-6)A cm^(-2)and 3.77×10^(-6)cm^(-2)s^(-1)when NORR was driven by overpotentials.These findings revealed the potential of CuO-NF for NO reduction and provided insights into the intricate interplay between crystal morphology,valence states,and electrochemical performance.
基金Project supported by the Natural Science Foundation of Heilongjiang Province,China(Grant No.LH2022A026)the National Key Research and Development Program of China(Grant No.2022YFA1602500)+2 种基金the National Natural Science Foundation of China(Grant No.11934004)Fundamental Research Funds in Heilongjiang Province Universities,China(Grant No.145109309)Foundation of National Key Laboratory of Computational Physics(Grant No.6142A05QN22006)。
文摘The SiS molecule,which plays a significant role in space,has attracted a great deal of attention for many years.Due to complex interactions among its low-lying electronic states,precise information regarding the molecular structure of SiS is limited.To obtain accurate information about the structure of its excited states,the high-precision multireference configuration interaction(MRCI)method has been utilized.This method is used to calculate the potential energy curves(PECs)of the 18Λ–S states corresponding to the lowest dissociation limit of SiS.The core–valence correlation effect,Davidson’s correction and the scalar relativistic effect are also included to guarantee the precision of the MRCI calculation.Based on the calculated PECs,the spectroscopic constants of quasi-bound and bound electronic states are calculated and they are in accordance with previous experimental results.The transition dipole moments(TDMs)and dipole moments(DMs)are determined by the MRCI method.In addition,the abrupt variations of the DMs for the 1^(5)Σ^(+)and 2^(5)Σ^(+)states at the avoided crossing point are attributed to the variation of the electronic configuration.The opacity of SiS at a pressure of 100 atms is presented across a series of temperatures.With increasing temperature,the expanding population of excited states blurs the band boundaries.
基金Project supported by the National Natural Science Foundation of China (Grant No.12074367)Anhui Initiative in Quantum Information Technologies,the National Key Research and Development Program of China (Grant No.2020YFA0309804)+3 种基金Shanghai Municipal Science and Technology Major Project (Grant No.2019SHZDZX01)the Strategic Priority Research Program of Chinese Academy of Sciences (Grant No.XDB35020200)Innovation Program for Quantum Science and Technology (Grant No.2021ZD0302002)New Cornerstone Science Foundation。
文摘We investigated the one-dimensional diamond ladder in the momentum lattice platform. By inducing multiple twoand four-photon Bragg scatterings among specific momentum states, we achieved a flat band system based on the diamond model, precisely controlling the coupling strength and phase between individual lattice sites. Utilizing two lattice sites couplings, we generated a compact localized state associated with the flat band, which remained localized throughout the entire time evolution. We successfully realized the continuous shift of flat bands by adjusting the corresponding nearest neighbor hopping strength, enabling us to observe the complete localization process. This opens avenues for further exploration of more complex properties within flat-band systems, including investigating the robustness of flat-band localized states in disordered flat-band systems and exploring many-body localization in interacting flat-band systems.
文摘Background: Nigeria, a nation grappling with rapid population growth, economic intricacies, and complex healthcare challenges, particularly in Lagos State, the economic hub and most populous state, faces the challenge of ensuring quality healthcare access. The overview of the effect of quality improvement initiatives in this paper focuses on private healthcare providers in Lagos State, Nigeria. The study assesses the impact of donor-funded quality improvement projects on these private healthcare facilities. It explores the level of participation, perceived support, and tangible effects of the initiatives on healthcare delivery within private healthcare facilities. It also examines how these initiatives influence patient inflow and facility ratings, and bring about additional benefits and improvements, provides insights into the challenges faced by private healthcare providers in implementing quality improvement projects and elicits recommendations for improving the effectiveness of such initiatives. Methods: Qualitative research design was employed for in-depth exploration, utilizing semi-structured interviews. Private healthcare providers in Lagos involved in the SP4FP Quality Improvement Project were purposively sampled for diversity. Face-to-face interviews elicited insights into participation, perceived support, and project effects. Questions covered participation levels, support perception, changes observed, challenges faced, and recommendations. Thematic analysis identified recurring themes from interview transcripts. Adherence to ethical guidelines ensured participant confidentiality and informed consent. Results: Respondents affirmed active involvement in the SP4FP Quality Improvement Project, echoing literature emphasizing private-sector collaboration with the public sector. While acknowledging positive influences on facility ratings, respondents highlighted challenges within the broader Nigerian healthcare landscape affecting patient numbers. Respondents cited tangible improvements, particularly in staff management and patient care processes, validating the positive influence of quality improvement projects. Financial constraints emerged as a significant challenge, aligning with existing literature emphasizing the pragmatic difficulties faced by private healthcare providers. Conclusions: This study illuminates the complex landscape of private healthcare provision in Lagos State, emphasizing the positive impact of donor-funded quality improvement projects. The findings provide nuanced insights, guiding policymakers, healthcare managers, and practitioners toward collaborative, sustainable improvements. As Nigeria progresses, these lessons will be crucial in shaping healthcare policies prioritizing population well-being.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11975095,12075082,11935006,and 12247105)the Major Sci-Tech Program of Hunan Province,China(Grant No.2023ZJ1010)the Natural Science Foundation of Guangdong Province,China(Grant Nos.2019A1515011400 and 2023A151501223).
文摘We study the chiral bound states in a coupled-resonator array with staggered hopping strengths,which interacts with a two-level small atom through a single coupling point or two adjacent ones.In addition to the two typical bound states found above and below the energy bands,this system presents an extraordinary chiral bound state located within the energy gap.We use the chirality to quantify the breaking of the mirror symmetry.We find that the chirality value undergoes continuous changes by tuning the coupling strengths.The preferred direction of the chirality is controlled not only by the competition between the intracell and the intercell hoppings in the coupled-resonator array,but also by the coherence between the two coupling points.In the case with one coupling point,the chirality values varies monotonously with difference between the intracell hopping and the intercell hoppings.While in the case with two coupling points,due to the coherence between the two coupling points the perfect chiral states can be obtained.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.12274178 and 12174148)Support of High Performance Computing Center of Jilin Universitythe high-performance computing cluster Tiger@IAMP。
文摘Information about electronic excited states of molecular anions plays an important role in investigating electron attachment and detachment processes.Here we present a high-level theoretical study of the electronic structures of 12 alkali-metal-containing diatomic anions MX-(MX = LiH,LiF,LiCl,NaF,NaCl,NaBr,RbCl,KCl,KBr,RbI,KI and CsI).The equation-of-motion electron-attachment coupled-cluster singles and doubles(EOM-EA-CCSD) method is used to calculate the electron binding energies(EBEs) of 10 electronic excited states of each of the 12 molecule anions.With addition of different s-/p-/d-type diffusion functions in the basis set,we have identified possible excited dipole bound states(DBSs) of each anion.With the investigation of EBEs on the 12 MXs with dipole moment(DM) up to 12.1 D,we evaluate the dependence of the number of anionic excited DBSs on molecular DM.The results indicate that there are at least two or three DBSs of anions with a molecular DM larger than 7 D and a molecule with DM > 10 D can sustain a π-DBS of the anion.Our study has some implications for the excited DBS electronic states of alkali-metal-containing diatomic molecules.
文摘Plants play an essential role in matter and energy transformations and are key messengers in the carbon and energy cycle. Net primary productivity (NPP) reflects the capability of plants to transform solar energy into photosynthesis. It is very sensible for factors affecting on vegetation variability such as climate, soils, plant characteristics and human activities. So, it can be used as an indicator of actual and potential trend of vegetation. In this study we used the actual NPP which was derived from MODIS to assess the response of NPP to climate variables in Gadarif State, from 2000 to 2010. The correlations between NPP and climate variables (temperature and precipitation) are calculated using Pearson’s Correlation Coefficient and ordinary least squares regression. The main results show the following 1) the correlation Coefficient between NPP and mean annual temperature is Somewhat negative for Feshaga, Rahd, Gadarif and Galabat areas and weakly negative in Faw area;2) the correlation Coefficient between NPP and annual total precipitation is weakly negative in Faw, Rahd and Galabat areas and somewhat negative in Galabat and Rahd areas. This study demonstrated that the correlation analysis between NPP and climate variables (precipitation and temperature) gives reliably result of NPP responses to climate variables that is clearly in a very large scale of study area.
基金Project supported by the National Key R&D Program of China (Grant No. 2022YFA1403203)the Innovation Program for Quantum Science and Technology (Grant No. 2021ZD0302802)+3 种基金the National Natural Science Foundation of China (Grant Nos. 12074002, 12374133, and 11804379)the Major Basic Program of Natural Science Foundation of Shandong Province (Grant No. ZR2021ZD01)the supports of the National Natural Science Foundation of China (Grant No. 12274001)the Natural Science Foundation of Anhui Province (Grant No. 2208085MA09)。
文摘We revisited the vortex states of 2H-NbSe_(2) towards zero fields by a low-temperature scanning tunneling microscope.Fine structures of the anisotropic vortex states were distinguished, one is a spatially non-splitting zero bias peak, and the other is an in-gap conductance anomaly resembling evolved crossing features around the center of the three nearest vortices.Both of them distribute solely along the next nearest neighboring direction of the vortex lattice and become unresolved in much higher magnetic fields, implying an important role played by the vortex–vortex interactions. To clarify these issues,we have studied the intrinsic vortex states of the isolated trapped vortex in zero fields at 0.45 K. It is concluded that the anisotropic zero bias peak is attributed to the superconducting gap anisotropy, and the spatially evolved crossing features are related to the vortex–vortex interaction. The vortex core size under the zero-field limit is determined. These results provide a paradigm for studying the inherent vortex states of type-II superconductors especially based on an isolated vortex.
文摘We explore the entanglement features of pure symmetric N-qubit states characterized by N-distinct spinors with a particular focus on the Greenberger-Horne-Zeilinger (GHZ) states and , an equal superposition of W and obverse W states. Along with a comparison of pairwise entanglement and monogamy properties, we explore the geometric information contained in them by constructing their canonical steering ellipsoids. We obtain the volume monogamy relations satisfied by states as a function of number of qubits and compare with the maximal monogamy property of GHZ states.
基金supported by the National Natural Science Foundation of China(Grant Nos.12074209 and 12274063)the Fundamental Research Funds for the Central Universities(Grant No.ZYGX2019J100)the Open Project of State Key Laboratory of Low-Dimensional Quantum Physics(Grant No.KF202008)。
文摘We investigate the nonlocal transport modulated by Coulomb interactions in devices comprising two interacting Majorana wires,where both nanowires are in proximity to a mesoscopic superconducting(SC)island.Each Majorana bound state(MBS)is coupled to one lead via a quantum dot with resonant levels.In this device,the nonlocal correlations can be induced in the absence of Majorana energy splitting.We find that the negative differential conductance and giant current noise cross correlation could be induced,due to the interplay between nonlocality of MBSs and dynamical Coulomb blockade effect.This feature may provide a signature for the existence of the MBSs.
基金supported by National Natural Science Foundation of China(22021004).
文摘1-hexene aromatization is a promising technology to convert excess olefin in fluid catalytic cracking(FCC)gasoline to high-value benzene(B),toluene(T),and xylene.Besides,the increasing market demand of xylene has put forward higher requirements for new generation of catalyst.For increasing xylene yield in 1-hexene aromatization,the effect of mesopore structure and spatial distribution on product distribution and Zn loading was studied.Catalysts with different mesopore spatial distribution were prepared by post-treatment of parent HZSM-5 zeolite,including NaOH treatment,tetra-propylammonium hydroxide(TPAOH)treatment,and recrystallization.It was found the evenly distributed mesopore mainly prolongs the catalyst lifetime by enhancing diffusion properties but reduces the aromatics selectivity,as a result of damage of micropores close to the catalyst surface.While the selectivity of high-value xylene can be highly promoted when the mesopore is mainly distributed interior the catalyst.Besides,the state of loaded Zn was also affected by mesopores spatial distribution.On the optimized catalyst,the xylene selectivity was enhanced by 12.4%compared with conventional Zn-loaded parent HZSM-5 catalyst at conversion over 99%.It was attributed to the synergy effect of mesopores spatial distribution and optimized acid properties.This work reveals the role of mesopores in different spatial positions of 1-hexene aromatization catalysts in the reaction process and the influence on metal distribution,as well as their synergistic effect two on the improvement of xylene selectivity,which can improve our understanding of catalyst pore structure and be helpful for the rational design of high-efficient catalyst.
基金financially supported by Ministry of Science and Higher Education of the Russian Federation(Grant No.FENU-2023-0013)。
文摘The high entropy alloys(HEAs)are the newly developed high-performance materials that have gained significant importance in defence,nuclear and aerospace sector due to their superior mechanical properties,heat resistance,high temperature strength and corrosion resistance.These alloys are manufactured by the equal mixing or larger proportions of five or more alloying elements.HEAs exhibit superior mechanical performance compared to traditional engineering alloys because of the extensive alloying composition and higher entropy of mixing.Solid state welding(SSW)techniques such as friction stir welding(FSW),rotary friction welding(RFW),diffusion bonding(DB)and explosive welding(EW)have been efficiently deployed for improving the microstructural integrity and mechanical properties of welded HEA joints.The HEA interlayers revealed greater potential in supressing the formation of deleterious intermetallic phases and maximizing the mechanical properties of HEAs joints.The similar and dissimilar joining of HEAs has been manifested to be viable for HEA systems which further expands their industrial applications.Thus,the main objective of this review paper is to present a critical review of current state of research,challenges and opportunities and main directions in SSW of HEAs mainly CoCrFeNiMn and Al_xCoCrFeNi alloys.The state of the art of problems,progress and future outlook in SSW of HEAs are critically reviewed by considering the formation of phases,microstructural evolution and mechanical properties of HEAs joints.
文摘Assessment of past-climate simulations of regional climate models(RCMs)is important for understanding the reliability of RCMs when used to project future regional climate.Here,we assess the performance and discuss possible causes of biases in a WRF-based RCM with a grid spacing of 50 km,named WRFG,from the North American Regional Climate Change Assessment Program(NARCCAP)in simulating wet season precipitation over the Central United States for a period when observational data are available.The RCM reproduces key features of the precipitation distribution characteristics during late spring to early summer,although it tends to underestimate the magnitude of precipitation.This dry bias is partially due to the model’s lack of skill in simulating nocturnal precipitation related to the lack of eastward propagating convective systems in the simulation.Inaccuracy in reproducing large-scale circulation and environmental conditions is another contributing factor.The too weak simulated pressure gradient between the Rocky Mountains and the Gulf of Mexico results in weaker southerly winds in between,leading to a reduction of warm moist air transport from the Gulf to the Central Great Plains.The simulated low-level horizontal convergence fields are less favorable for upward motion than in the NARR and hence,for the development of moist convection as well.Therefore,a careful examination of an RCM’s deficiencies and the identification of the source of errors are important when using the RCM to project precipitation changes in future climate scenarios.