In response to the current issues in the construction of software engineering(SE)degree granting program,such as insufficient resource integration,low level of internationalization,and inadequate quality control,we pr...In response to the current issues in the construction of software engineering(SE)degree granting program,such as insufficient resource integration,low level of internationalization,and inadequate quality control,we propose the Software Engineering Degree Granting Program Construction Practice Project at Harbin Institute of Technology(HIT).This project aims to explore new models for software talent cultivation,establish a superior SE degree granting program,and ultimately cultivate outstanding internationalized composite SE professionals to support the high-quality development of the national software industry.To this end,we design a distinctive overall construction idea and plan for the SE degree granting program,which are characterized by“3I3S:three highlights for specialized cultivation and strictness in three aspects to ensure quality control”.After years of practice and validation of the project at the School of Software at HIT,this project has proven effective in optimizing talent cultivation models,enhancing students’practical abilities,promoting international exchange and cooperation,advancing industry-education integration,and meeting industrial needs.展开更多
Accelerating the development of students is the basic goal of postgraduate talent cultivation.The final research results,employment situation and satisfaction of postgraduate students with school education are more im...Accelerating the development of students is the basic goal of postgraduate talent cultivation.The final research results,employment situation and satisfaction of postgraduate students with school education are more important indicators of the quality of talent cultivation in a university.For having a deeper understanding of the satisfaction of postgraduates in Harbin Institute of Technology(Weihai)in terms of motivation,tutor situation,management service and employment situation,a questionnaire survey was conducted on postgraduates.The survey results show that the overall satisfaction of postgraduates is high.In terms of studying motivation,most postgraduates think that their majors are more related to employment;in terms of professors,most of them can get along well with their professors and learn from the advantages of their professors;in terms of school management,they respond well to the"library",but think that the"dormitory"and"canteen"need further improvement;in terms of employment,most of postgraduates choose to be employed,while a few of them choose to further their studies,most of which have applied to study in domestic or foreign universities.展开更多
Graduate student recruitment publicity is a very important link in graduate student recruitment,the quality of students directly affects the quality of graduate education.Taking Harbin Institute of Technology(Weihai)a...Graduate student recruitment publicity is a very important link in graduate student recruitment,the quality of students directly affects the quality of graduate education.Taking Harbin Institute of Technology(Weihai)as the research object,this paper analyzes the internal and external factors affecting the improvement of graduate student quality in the branch campus,and carries out the corresponding countermeasures,puts forward the propaganda strategy of all-round research and recruitment,and effectively improves the quality of graduate student in the branch campus.展开更多
Harbin Institute of Technology(HIT)was established in 1920 in Harbin,Heilongjiang,China.In 1954,HIT became one of China’s first six leading universities.Presently HIT is a member of China’s top nine University Union...Harbin Institute of Technology(HIT)was established in 1920 in Harbin,Heilongjiang,China.In 1954,HIT became one of China’s first six leading universities.Presently HIT is a member of China’s top nine University Union(C9).It is a National Key University with science and engineering as its core and has developed with management,liberal arts,economy.展开更多
The burning of fossil fuels in industry results in significant carbon emissions,and the heat generated is often not fully utilized.For high-temperature industries,thermophotovoltaics(TPVs)is an effective method for wa...The burning of fossil fuels in industry results in significant carbon emissions,and the heat generated is often not fully utilized.For high-temperature industries,thermophotovoltaics(TPVs)is an effective method for waste heat recovery.This review covers two aspects of high-efficiency TPV systems and industrial waste heat applications.At the system level,representative results of TPV complete the systems,while selective emitters and photovoltaic cells in the last decade are compiled.The key points of components to improve the energy conversion efficiency are further analyzed,and the related micro/nano-fabrication methods are introduced.At the application level,the feasibility of TPV applications in high-temperature industries is shown from the world waste heat utilization situation.The potential of TPV in waste heat recovery and carbon neutrality is illustrated with the steel industry as an example.展开更多
Developing effective strategies to regulate graphene’s conduction loss and polarization has become a key to expanding its application in the electromagnetic wave absorption(EMWA)field.Based on the unique energy band ...Developing effective strategies to regulate graphene’s conduction loss and polarization has become a key to expanding its application in the electromagnetic wave absorption(EMWA)field.Based on the unique energy band structure of graphene,regulating its bandgap and electrical properties by introducing heteroatoms is considered a feasible solution.Herein,metal-nitrogen doping reduced graphene oxide(M–N-RGO)was prepared by embedding a series of single metal atoms M–N_(4) sites(M=Mn,Fe,Co,Ni,Cu,Zn,Nb,Cd,and Sn)in RGO using an N-coordination atom-assisted strategy.These composites had adjustable conductivity and polarization to optimize dielectric loss and impedance matching for efficient EMWA performance.The results showed that the minimum reflection loss(RL_(min))of Fe–N-RGO reaches−74.05 dB(2.0 mm)and the maximum effective absorption bandwidth(EAB_(max))is 7.05 GHz(1.89 mm)even with a low filler loading of only 1 wt%.Combined with X-ray absorption spectra(XAFS),atomic force microscopy,and density functional theory calculation analysis,the Fe–N_(4) can be used as the polarization center to increase dipole polarization,interface polarization and defect-induced polarization due to d-p orbital hybridization and structural distortion.Moreover,electron migration within the Fe further leads to conduction loss,thereby synergistically promoting energy attenuation.This study demonstrates the effectiveness of metal-nitrogen doping in regulating the graphene′s dielectric properties,which provides an important basis for further investigation of the loss mechanism.展开更多
With the widespread use of Chinese globally, the number of Chinese learners has been increasing, leading to various grammatical errors among beginners. Additionally, as domestic efforts to develop industrial informati...With the widespread use of Chinese globally, the number of Chinese learners has been increasing, leading to various grammatical errors among beginners. Additionally, as domestic efforts to develop industrial information grow, electronic documents have also proliferated. When dealing with numerous electronic documents and texts written by Chinese beginners, manually written texts often contain hidden grammatical errors, posing a significant challenge to traditional manual proofreading. Correcting these grammatical errors is crucial to ensure fluency and readability. However, certain special types of text grammar or logical errors can have a huge impact, and manually proofreading a large number of texts individually is clearly impractical. Consequently, research on text error correction techniques has garnered significant attention in recent years. The advent and advancement of deep learning have paved the way for sequence-to-sequence learning methods to be extensively applied to the task of text error correction. This paper presents a comprehensive analysis of Chinese text grammar error correction technology, elaborates on its current research status, discusses existing problems, proposes preliminary solutions, and conducts experiments using judicial documents as an example. The aim is to provide a feasible research approach for Chinese text error correction technology.展开更多
Hydrogel scaffolds have numerous potential applications in the tissue engineering field.However,tough hydrogel scaffolds implanted in vivo are seldom reported because it is difficult to balance biocompatibility and hi...Hydrogel scaffolds have numerous potential applications in the tissue engineering field.However,tough hydrogel scaffolds implanted in vivo are seldom reported because it is difficult to balance biocompatibility and high mechanical properties.Inspired by Chinese ramen,we propose a universal fabricating method(printing-P,training-T,cross-linking-C,PTC&PCT)for tough hydrogel scaffolds to fill this gap.First,3D printing fabricates a hydrogel scaffold with desired structures(P).Then,the scaffold could have extraordinarily high mechanical properties and functional surface structure by cycle mechanical training with salting-out assistance(T).Finally,the training results are fixed by photo-cross-linking processing(C).The tough gelatin hydrogel scaffolds exhibit excellent tensile strength of 6.66 MPa(622-fold untreated)and have excellent biocompatibility.Furthermore,this scaffold possesses functional surface structures from nanometer to micron to millimeter,which can efficiently induce directional cell growth.Interestingly,this strategy can produce bionic human tissue with mechanical properties of 10 kPa-10 MPa by changing the type of salt,and many hydrogels,such as gelatin and silk,could be improved with PTC or PCT strategies.Animal experiments show that this scaffold can effectively promote the new generation of muscle fibers,blood vessels,and nerves within 4 weeks,prompting the rapid regeneration of large-volume muscle loss injuries.展开更多
Constructed wetlands(CWs)are a promising method to treat effluent from wastewater treatment plants(WWTPs).However,low carbon/nitrogen(C/N)ratios of the influent inhibit denitrification in CWs,resulting in poor nitroge...Constructed wetlands(CWs)are a promising method to treat effluent from wastewater treatment plants(WWTPs).However,low carbon/nitrogen(C/N)ratios of the influent inhibit denitrification in CWs,resulting in poor nitrogen removal efficiency.Herein,we compared traditional(control),biochar(BC),and b-cyclodextrin-functionalized biochar(BC@b-CD)CW systems to investigate nitrogen removal from influent with low C/N ratios,and the mechanisms that enhance this process.The highest nitrogen removal rates were observed in the BC@b-CD group,with rates 45.89%and 42.48%higher than those of the control,accompanied by a 70.57%and 85.45%decrease in nitrous oxide release,when the C/N ratio decreased from 4 to 2,respectively.Metagenomic and enzymatic analyses indicated that BC@b-CD enhances nitrogen removal by coordinately promoting carbon metabolism and increasing denitrification enzyme activities,without affecting microbial species diversity in CWs.Structural equation modeling confirmed that the foremost advantages of BC@b-CD were effective electron generation and transportation resulting from increased activities of nicotinamide adenine dinucleotide(NADH)dehydrogenase and the electron transfer system(ETS),thereby strategically reallocating more carbon metabolic flow to support denitrification.Our results show that the application of BC@b-CD in CWs to optimize the reallocation of electrons from carbon metabolism is a feasible strategy to enhance denitrification under low C/N conditions.展开更多
Lithium-sulfur(Li-S)batteries with high energy density suffer from the soluble lithium polysulfide species,Traditional metal sulfides containing a single metal element used as electrocatalysts for Li-S batteries commo...Lithium-sulfur(Li-S)batteries with high energy density suffer from the soluble lithium polysulfide species,Traditional metal sulfides containing a single metal element used as electrocatalysts for Li-S batteries commonly have limited catalytic abilities to improve battery performance.Herein,based on the Hume-Rothery rule and solvothermal method,the high-entropy sulfide NiCoCuTiVS_(x)derived from Co_(9)S_(8)was designed and synthesized,to realize the combination of small local strain and excellent catalytic performance.With all five metal elements(Ni,Co,Cu,Ti,and V)capable of chemical interactions with soluble polysulfides,NiCoCuTiVS_(x)exhibited strong chemical confinement of polysulfides and promoted fast kinetics for polysulfides conversion.Consequently,the S/NiCoCuTiVS_(x)cathode can maintain a high discharge capacity of 968.9 mA h g^(-1)after 200 cycles at 0.5 C and its capacity retention is 1.3 times higher than that of S/Co_(9)S_(8).The improved cycle stability can be attributed to the synergistic effect originating from the multiple metal elements,coupled with the reduced nucleation and activation barriers of Li_(2)S.The present work opens a path to explore novel electrocatalyst materials based on high entropy materials for the achievement of advanced Li-S batteries.展开更多
Low earth orbit(LEO)satellites with wide coverage can carry the mobile edge computing(MEC)servers with powerful computing capabilities to form the LEO satellite edge computing system,providing computing services for t...Low earth orbit(LEO)satellites with wide coverage can carry the mobile edge computing(MEC)servers with powerful computing capabilities to form the LEO satellite edge computing system,providing computing services for the global ground users.In this paper,the computation offloading problem and resource allocation problem are formulated as a mixed integer nonlinear program(MINLP)problem.This paper proposes a computation offloading algorithm based on deep deterministic policy gradient(DDPG)to obtain the user offloading decisions and user uplink transmission power.This paper uses the convex optimization algorithm based on Lagrange multiplier method to obtain the optimal MEC server resource allocation scheme.In addition,the expression of suboptimal user local CPU cycles is derived by relaxation method.Simulation results show that the proposed algorithm can achieve excellent convergence effect,and the proposed algorithm significantly reduces the system utility values at considerable time cost compared with other algorithms.展开更多
Magnesium alloys have gained extensive applications across various industries,including aerospace,transportation,and civil construction,owing to their excellent combinations of high specific strength and stiffness[1]....Magnesium alloys have gained extensive applications across various industries,including aerospace,transportation,and civil construction,owing to their excellent combinations of high specific strength and stiffness[1].However,their lim-ited strength due to the lack of effective strengthening phases has hindered their broader industrial applications[2].Never-theless,it has been challenging to achieve significant strength-ening due to the restricted solubility of alloying elements in magnesium[3].Thus,more and more efforts have been made to explore the concept of secondary phase-reinforced magne-sium alloys[2,4,5],where the secondary phase acts as re-inforcing agents within the magnesium matrix,resembling a composite material.展开更多
The inherent brittle behavior and ductile-to-brittle transition(DBT)mechanism of Sn−3.0Ag−0.5Cu(SAC305)solder alloy at the liquid nitrogen temperature(LNT,77 K)were investigated through uniaxial tensile experiments co...The inherent brittle behavior and ductile-to-brittle transition(DBT)mechanism of Sn−3.0Ag−0.5Cu(SAC305)solder alloy at the liquid nitrogen temperature(LNT,77 K)were investigated through uniaxial tensile experiments conducted at different temperatures.Dynamic recovery and recrystallization of SAC305 solder alloy at room temperature(RT,293 K)activate a softening process.Conversely,intersecting and none-intersecting deformation twins,embedded in body-centered tetragonal Sn,enhance tensile strength and stabilize strain hardening rate,while suppressing the elongation of the alloy at LNT.The irreconcilable velocity difference between twin thickening(~8μm/s)and dislocation slip(4μm/s)results in premature brittle fracture,during the linear hardening and DBT.Moreover,the secondary phases degrade the mechanical property of SAC305 solder alloy,and micro-cracks appear between Cu_(6)Sn_(5)and Ag_(3)Sn in the eutectic matrix.展开更多
The excellent irradiation resistance,high strength and plasticity exhibited by high-entropy alloys(HEAs)make it candidate for engin-eering applications.Diffusion bonding of Al_(0.3)CoCrFeNi single-phase HEAs was carri...The excellent irradiation resistance,high strength and plasticity exhibited by high-entropy alloys(HEAs)make it candidate for engin-eering applications.Diffusion bonding of Al_(0.3)CoCrFeNi single-phase HEAs was carried out using electric-assisted diffusion bonding(EADB),and the effect of bonding temperature on the evolution of the interfacial microstructure and the mechanical properties was investigated.The results indicate that as the bonding temperature increases,the pores at the interface gradually decrease in size and undergo closure.The electric current significantly promotes the pore closure mechanism dominated by plastic deformation at the diffusion interface and promotes the recrystallisation behavior at the interface,and the fracture mode changes from intergranular fracture at the interface to jagged fracture along the grains spanning the weld parent material.Due to the activation effect of EADB,higher-strength diffusion bonding of high-entropy alloys can be achieved at the same temperature compared with the conventional hot-pressure diffusion bonding(HPDB)process.展开更多
To quantify the seismic resilience of buildings,a method for evaluating functional loss from the component level to the overall building is proposed,and the dual-parameter seismic resilience assessment method based on...To quantify the seismic resilience of buildings,a method for evaluating functional loss from the component level to the overall building is proposed,and the dual-parameter seismic resilience assessment method based on postearthquake loss and recovery time is improved.A threelevel function tree model is established,which can consider the dynamic changes in weight coefficients of different category of components relative to their functional losses.Bayesian networks are utilized to quantify the impact of weather conditions,construction technology levels,and worker skill levels on component repair time.A method for determining the real-time functional recovery curve of buildings based on the component repair process is proposed.Taking a three-story teaching building as an example,the seismic resilience indices under basic earthquakes and rare earthquakes are calculated.The results show that the seismic resilience grade of the teaching building is comprehensively judged as GradeⅢ,and its resilience grade is more significantly affected by postearthquake loss.The proposed method can be used to predict the seismic resilience of buildings prior to earthquakes,identify weak components within buildings,and provide guidance for taking measures to enhance the seismic resilience of buildings.展开更多
Laser twin-arc GTAW(LTA-GTAW)process has been developed by using the synergic interaction effects of laser and a coupled arc in a weld pool to achieve higher energy efficiency.In this study,bead-on-plate welding was c...Laser twin-arc GTAW(LTA-GTAW)process has been developed by using the synergic interaction effects of laser and a coupled arc in a weld pool to achieve higher energy efficiency.In this study,bead-on-plate welding was conducted on 8-mm-thick Q235B work-pieces to investigate the variation of hybrid arc profile,the influence of hybrid arc profile on weld forming,microstructure and mech-anical properties of the joint during the LTA-GTAW process.The influence of Laser-GTAW and LTA-GTAW methods on weld surface appearance,heat input per unit length,and weld metal microstructure were also demonstrated systematically.The LTA-GTAW can make the distribution of arc energy more reasonable in welding depth and width.When defocus is 0,I_(f)is 330 A,I_(b)is 240 A,laser power is 2.4 kW,and spacing between heat sources of tungsten electrode is 10 mm,the weld shape is better.Compared with Laser-GTAW,LTA-GTAW can achieve lower heat input at the same penetration depth,and the microstructure of the weld is refined.The tensile strength of the welded joint is 121.8%of the base material,and the fracture mode of the welded joint is ductile fracture,the comprehensive mechanical properties are better.展开更多
Microstructures and properties of mortar using ammonium phosphate and potassium phosphate were tested and compared in this case.Moreover,two cementitious additions and two lightweight aggregates,including fly ash,redi...Microstructures and properties of mortar using ammonium phosphate and potassium phosphate were tested and compared in this case.Moreover,two cementitious additions and two lightweight aggregates,including fly ash,redispersible latex powder,ceramsite sand,and rubber powder,were respectively tried to be applied in magnesium ammonium phosphate cement mortar in order to modify the microstructures and properties.The experimental results show that potassium phosphate is not suitable for magnesium phosphate cement mortar for cold region construction purpose.Although fly ash can bring positive modification in the condition of normal temperature curing,it brings negative effects in the condition of sub-zero temperature curing.Either redispersible latex powder or ceramsite sand can improve the freeze-thaw cycling resistance of magnesium phosphate cement mortar in the conditions of low temperature coupled with freeze-thaw cycling,but only the ceramsite sand can improve both mechanical properties and freeze-thaw cycling resistance.The modification caused by ceramsite sand is mainly due to the exceptional bonding strength between hardened cement paste and the porous surface of ceramsite and the porous structure of ceramsite for the release of frost heave stress.展开更多
In this study,the rotary movement of the tungsten needle in gas tungsten arc welding(GTAW)process was realized by direct current motor.The arc characteristics,the flow of molten pool and the microstructure and propert...In this study,the rotary movement of the tungsten needle in gas tungsten arc welding(GTAW)process was realized by direct current motor.The arc characteristics,the flow of molten pool and the microstructure and properties of the weld bead were studied.The results showed that the rotary motion of the tungsten needle transferred circumferential momentum to the arc as well as the molten pool,thereby conferring the latter with rotating fluid flow characteristics.Under the action of a relatively spiraling shielding gas,arc constriction occurred,and molten pool width dropped considerably.A finer and more uniform precipitated phase in the matrix,as well as a fewer large-medium pores,were achieved in the 5A06 aluminum alloy weld metal using this modified GTAW process,which noticeably increased the bending strength and tensile strength of weld metal and the microhardness of fusion zone.展开更多
While laser surface texturing(LST)is a promising manufacturing technique for surface functionalization,simultaneously realizing high precision and high efficiency in the LST of complex curved surface is challenging,du...While laser surface texturing(LST)is a promising manufacturing technique for surface functionalization,simultaneously realizing high precision and high efficiency in the LST of complex curved surface is challenging,due to continuously varied geometries of laser-matter incidence.In the present work,we propose a novel manufacturing system of 7-axis on-the-fly LST for complex curved surface,based on the integrated synchronization of 5-axis linkage motion platform with 2-axis galvanometer.Specifically,the algorithm for decomposing spatial texture trajectory on curved surface into low-frequency and high-frequency parts is established,based on which the kinematic model of synchronized 7-axis system is developed to derive the motion of each axis in both 5-axis linkage motion platform and 2-axis galvanometer simultaneously.Subsequently,the synchronized 7-axis LST system is experimentally realized,including the setup of mechanical stages integrated with optical path,the configuration of numerical control unit,and the development of processing software.Finally,case study of 7-axis on-the-fly LST of freeform aluminum surface is performed,and the advantages in terms of processing efficiency and texturing accuracy over 5-axis linkage LST are demonstrated.The correlation of reduced following errors between mechanical stages with the promoted performance of curved surface texturing by the 7-axis on-the-fly LST is further analyzed.Current work provides a feasible solution for establishing the manufacturing system for high performance LST of complex curved surface.展开更多
High thermal conductivity and high strength Mg-1.5Mn-2.5Ce alloy with a tensile yield strength of 387.0 MPa,ultimate tensile strength of 395.8 MPa,and thermal conductivity of 142.1 W/(m·K)was successfully fabrica...High thermal conductivity and high strength Mg-1.5Mn-2.5Ce alloy with a tensile yield strength of 387.0 MPa,ultimate tensile strength of 395.8 MPa,and thermal conductivity of 142.1 W/(m·K)was successfully fabricated via hot extrusion.The effects of La and Ce additions on the microstructure,thermal conductivity,and mechanical properties of the Mg-1.5Mn alloy were investigated.The results indicated that both the as-extruded Mg-1.5Mn-2.5La and Mg-1.5Mn-2.5Ce alloys exhibited a bimodal grain structure,with dynamically precipitated nano-scaleα-Mn phases.In comparison with La,the addition of Ce enhanced the dynamic precipitation more effectively during hot extrusion,while its influence on promoting the dynamic recrystallization was relatively weaker.The high tensile strength obtained in the as-extruded Mg-1.5Mn-2.5RE alloys can be attributed to the combined influence of the bimodal grain structure(with fine dynamic recrystallized(DRXed)grain size and high proportion of un-dynamic recrystallized(unDRXed)grains),dense nano-scale precipitates,and broken Mg12RE phases,while the remarkable thermal conductivity was due to the precipitation of Mn-rich phases from the Mg matrix.展开更多
基金supported in part by the Education Reform Key Projects of Heilongjiang Province under Grant Nos.SJGZ20220011,SJGZ20220012,and SJGZY2024008。
文摘In response to the current issues in the construction of software engineering(SE)degree granting program,such as insufficient resource integration,low level of internationalization,and inadequate quality control,we propose the Software Engineering Degree Granting Program Construction Practice Project at Harbin Institute of Technology(HIT).This project aims to explore new models for software talent cultivation,establish a superior SE degree granting program,and ultimately cultivate outstanding internationalized composite SE professionals to support the high-quality development of the national software industry.To this end,we design a distinctive overall construction idea and plan for the SE degree granting program,which are characterized by“3I3S:three highlights for specialized cultivation and strictness in three aspects to ensure quality control”.After years of practice and validation of the project at the School of Software at HIT,this project has proven effective in optimizing talent cultivation models,enhancing students’practical abilities,promoting international exchange and cooperation,advancing industry-education integration,and meeting industrial needs.
基金was supported by Postgraduate Education and Teaching Reform Project of Shandong Province(SDYJG21018)Postgraduate Education and Teaching Reform Project of Harbin Institute of Technology at Weihai(WH2019002)Postgraduate Education and Teaching Reform Project of Harbin Institute of Technology(21HX1001).
文摘Accelerating the development of students is the basic goal of postgraduate talent cultivation.The final research results,employment situation and satisfaction of postgraduate students with school education are more important indicators of the quality of talent cultivation in a university.For having a deeper understanding of the satisfaction of postgraduates in Harbin Institute of Technology(Weihai)in terms of motivation,tutor situation,management service and employment situation,a questionnaire survey was conducted on postgraduates.The survey results show that the overall satisfaction of postgraduates is high.In terms of studying motivation,most postgraduates think that their majors are more related to employment;in terms of professors,most of them can get along well with their professors and learn from the advantages of their professors;in terms of school management,they respond well to the"library",but think that the"dormitory"and"canteen"need further improvement;in terms of employment,most of postgraduates choose to be employed,while a few of them choose to further their studies,most of which have applied to study in domestic or foreign universities.
基金This research was supported by Postgraduate Education and Teaching Reform Project of Shandong Province(SDYJG21018)Postgraduate Education and Teaching Reform Project of Harbin Institute of Technology at Weihai(WH2019002)Postgraduate Education and Teaching Reform Project of Harbin Institute of Technology(21HX1001).
文摘Graduate student recruitment publicity is a very important link in graduate student recruitment,the quality of students directly affects the quality of graduate education.Taking Harbin Institute of Technology(Weihai)as the research object,this paper analyzes the internal and external factors affecting the improvement of graduate student quality in the branch campus,and carries out the corresponding countermeasures,puts forward the propaganda strategy of all-round research and recruitment,and effectively improves the quality of graduate student in the branch campus.
文摘Harbin Institute of Technology(HIT)was established in 1920 in Harbin,Heilongjiang,China.In 1954,HIT became one of China’s first six leading universities.Presently HIT is a member of China’s top nine University Union(C9).It is a National Key University with science and engineering as its core and has developed with management,liberal arts,economy.
基金supported by the National Natural Science Foundation of China(No.52227813)China Postdoctoral Science Foundation(Nos.2023M740905,2023T160164)+3 种基金National Key ResearchDevelopment Program of China(No.2022YFE0210200)Natural Science Foundation of Heilongjiang Province(No.LH2023E043)the Fundamental Research Funds for the Central Universities(Nos.2022ZFJH04,HIT.OCEF.2021023)。
文摘The burning of fossil fuels in industry results in significant carbon emissions,and the heat generated is often not fully utilized.For high-temperature industries,thermophotovoltaics(TPVs)is an effective method for waste heat recovery.This review covers two aspects of high-efficiency TPV systems and industrial waste heat applications.At the system level,representative results of TPV complete the systems,while selective emitters and photovoltaic cells in the last decade are compiled.The key points of components to improve the energy conversion efficiency are further analyzed,and the related micro/nano-fabrication methods are introduced.At the application level,the feasibility of TPV applications in high-temperature industries is shown from the world waste heat utilization situation.The potential of TPV in waste heat recovery and carbon neutrality is illustrated with the steel industry as an example.
基金supported by National Natural Science Foundation of China(NSFC 52432002,52372041,52302087)Heilongjiang Touyan Team Program,the Fundamental Research Funds for the Central Universities(Grant No.HIT.OCEF.2021003)the Shanghai Aerospace Science and Technology Innovation Fund(SAST2022-60).
文摘Developing effective strategies to regulate graphene’s conduction loss and polarization has become a key to expanding its application in the electromagnetic wave absorption(EMWA)field.Based on the unique energy band structure of graphene,regulating its bandgap and electrical properties by introducing heteroatoms is considered a feasible solution.Herein,metal-nitrogen doping reduced graphene oxide(M–N-RGO)was prepared by embedding a series of single metal atoms M–N_(4) sites(M=Mn,Fe,Co,Ni,Cu,Zn,Nb,Cd,and Sn)in RGO using an N-coordination atom-assisted strategy.These composites had adjustable conductivity and polarization to optimize dielectric loss and impedance matching for efficient EMWA performance.The results showed that the minimum reflection loss(RL_(min))of Fe–N-RGO reaches−74.05 dB(2.0 mm)and the maximum effective absorption bandwidth(EAB_(max))is 7.05 GHz(1.89 mm)even with a low filler loading of only 1 wt%.Combined with X-ray absorption spectra(XAFS),atomic force microscopy,and density functional theory calculation analysis,the Fe–N_(4) can be used as the polarization center to increase dipole polarization,interface polarization and defect-induced polarization due to d-p orbital hybridization and structural distortion.Moreover,electron migration within the Fe further leads to conduction loss,thereby synergistically promoting energy attenuation.This study demonstrates the effectiveness of metal-nitrogen doping in regulating the graphene′s dielectric properties,which provides an important basis for further investigation of the loss mechanism.
文摘With the widespread use of Chinese globally, the number of Chinese learners has been increasing, leading to various grammatical errors among beginners. Additionally, as domestic efforts to develop industrial information grow, electronic documents have also proliferated. When dealing with numerous electronic documents and texts written by Chinese beginners, manually written texts often contain hidden grammatical errors, posing a significant challenge to traditional manual proofreading. Correcting these grammatical errors is crucial to ensure fluency and readability. However, certain special types of text grammar or logical errors can have a huge impact, and manually proofreading a large number of texts individually is clearly impractical. Consequently, research on text error correction techniques has garnered significant attention in recent years. The advent and advancement of deep learning have paved the way for sequence-to-sequence learning methods to be extensively applied to the task of text error correction. This paper presents a comprehensive analysis of Chinese text grammar error correction technology, elaborates on its current research status, discusses existing problems, proposes preliminary solutions, and conducts experiments using judicial documents as an example. The aim is to provide a feasible research approach for Chinese text error correction technology.
基金supported by the Innovative Research Group Project of the National Natural Science Foundation of China(T2121004)Key Programme(52235007)National Outstanding Youth Foundation of China(52325504).
文摘Hydrogel scaffolds have numerous potential applications in the tissue engineering field.However,tough hydrogel scaffolds implanted in vivo are seldom reported because it is difficult to balance biocompatibility and high mechanical properties.Inspired by Chinese ramen,we propose a universal fabricating method(printing-P,training-T,cross-linking-C,PTC&PCT)for tough hydrogel scaffolds to fill this gap.First,3D printing fabricates a hydrogel scaffold with desired structures(P).Then,the scaffold could have extraordinarily high mechanical properties and functional surface structure by cycle mechanical training with salting-out assistance(T).Finally,the training results are fixed by photo-cross-linking processing(C).The tough gelatin hydrogel scaffolds exhibit excellent tensile strength of 6.66 MPa(622-fold untreated)and have excellent biocompatibility.Furthermore,this scaffold possesses functional surface structures from nanometer to micron to millimeter,which can efficiently induce directional cell growth.Interestingly,this strategy can produce bionic human tissue with mechanical properties of 10 kPa-10 MPa by changing the type of salt,and many hydrogels,such as gelatin and silk,could be improved with PTC or PCT strategies.Animal experiments show that this scaffold can effectively promote the new generation of muscle fibers,blood vessels,and nerves within 4 weeks,prompting the rapid regeneration of large-volume muscle loss injuries.
基金supported by the National Natural Science Foundation of China(52321005)the Guangdong Basic and Applied Basic Research Foundation(2023A1515012383 and 2024A1515030138)+1 种基金the State Key Laboratory of Urban Water Resource and Environment(Harbin Institute of Technology,2021TS30)the Shenzhen Science and Technology Program(KQTD20190929172630447 and KCXFZ20211020163404007).
文摘Constructed wetlands(CWs)are a promising method to treat effluent from wastewater treatment plants(WWTPs).However,low carbon/nitrogen(C/N)ratios of the influent inhibit denitrification in CWs,resulting in poor nitrogen removal efficiency.Herein,we compared traditional(control),biochar(BC),and b-cyclodextrin-functionalized biochar(BC@b-CD)CW systems to investigate nitrogen removal from influent with low C/N ratios,and the mechanisms that enhance this process.The highest nitrogen removal rates were observed in the BC@b-CD group,with rates 45.89%and 42.48%higher than those of the control,accompanied by a 70.57%and 85.45%decrease in nitrous oxide release,when the C/N ratio decreased from 4 to 2,respectively.Metagenomic and enzymatic analyses indicated that BC@b-CD enhances nitrogen removal by coordinately promoting carbon metabolism and increasing denitrification enzyme activities,without affecting microbial species diversity in CWs.Structural equation modeling confirmed that the foremost advantages of BC@b-CD were effective electron generation and transportation resulting from increased activities of nicotinamide adenine dinucleotide(NADH)dehydrogenase and the electron transfer system(ETS),thereby strategically reallocating more carbon metabolic flow to support denitrification.Our results show that the application of BC@b-CD in CWs to optimize the reallocation of electrons from carbon metabolism is a feasible strategy to enhance denitrification under low C/N conditions.
基金financially supported by the National Natural Science Foundation of China(U22A20113,52261135543)。
文摘Lithium-sulfur(Li-S)batteries with high energy density suffer from the soluble lithium polysulfide species,Traditional metal sulfides containing a single metal element used as electrocatalysts for Li-S batteries commonly have limited catalytic abilities to improve battery performance.Herein,based on the Hume-Rothery rule and solvothermal method,the high-entropy sulfide NiCoCuTiVS_(x)derived from Co_(9)S_(8)was designed and synthesized,to realize the combination of small local strain and excellent catalytic performance.With all five metal elements(Ni,Co,Cu,Ti,and V)capable of chemical interactions with soluble polysulfides,NiCoCuTiVS_(x)exhibited strong chemical confinement of polysulfides and promoted fast kinetics for polysulfides conversion.Consequently,the S/NiCoCuTiVS_(x)cathode can maintain a high discharge capacity of 968.9 mA h g^(-1)after 200 cycles at 0.5 C and its capacity retention is 1.3 times higher than that of S/Co_(9)S_(8).The improved cycle stability can be attributed to the synergistic effect originating from the multiple metal elements,coupled with the reduced nucleation and activation barriers of Li_(2)S.The present work opens a path to explore novel electrocatalyst materials based on high entropy materials for the achievement of advanced Li-S batteries.
基金supported by National Natural Science Foundation of China No.62231012Natural Science Foundation for Outstanding Young Scholars of Heilongjiang Province under Grant YQ2020F001Heilongjiang Province Postdoctoral General Foundation under Grant AUGA4110004923.
文摘Low earth orbit(LEO)satellites with wide coverage can carry the mobile edge computing(MEC)servers with powerful computing capabilities to form the LEO satellite edge computing system,providing computing services for the global ground users.In this paper,the computation offloading problem and resource allocation problem are formulated as a mixed integer nonlinear program(MINLP)problem.This paper proposes a computation offloading algorithm based on deep deterministic policy gradient(DDPG)to obtain the user offloading decisions and user uplink transmission power.This paper uses the convex optimization algorithm based on Lagrange multiplier method to obtain the optimal MEC server resource allocation scheme.In addition,the expression of suboptimal user local CPU cycles is derived by relaxation method.Simulation results show that the proposed algorithm can achieve excellent convergence effect,and the proposed algorithm significantly reduces the system utility values at considerable time cost compared with other algorithms.
基金supported by the Guangdong Major Project of Basic and Applied Basic Research(No.2020B0301030006)the Guangdong Basic and Applied Basic Research Foundation[Grant No.2021B1515120071]R.Shi would like to thank the financial support from the open research fund of Songshan Lake Materials Laboratory(2021SLABFK06)and start-up funding from Harbin Institute of Technology(Shenzhen).
文摘Magnesium alloys have gained extensive applications across various industries,including aerospace,transportation,and civil construction,owing to their excellent combinations of high specific strength and stiffness[1].However,their lim-ited strength due to the lack of effective strengthening phases has hindered their broader industrial applications[2].Never-theless,it has been challenging to achieve significant strength-ening due to the restricted solubility of alloying elements in magnesium[3].Thus,more and more efforts have been made to explore the concept of secondary phase-reinforced magne-sium alloys[2,4,5],where the secondary phase acts as re-inforcing agents within the magnesium matrix,resembling a composite material.
基金supported by the National Natural Science Foundation of China(No.51775141)。
文摘The inherent brittle behavior and ductile-to-brittle transition(DBT)mechanism of Sn−3.0Ag−0.5Cu(SAC305)solder alloy at the liquid nitrogen temperature(LNT,77 K)were investigated through uniaxial tensile experiments conducted at different temperatures.Dynamic recovery and recrystallization of SAC305 solder alloy at room temperature(RT,293 K)activate a softening process.Conversely,intersecting and none-intersecting deformation twins,embedded in body-centered tetragonal Sn,enhance tensile strength and stabilize strain hardening rate,while suppressing the elongation of the alloy at LNT.The irreconcilable velocity difference between twin thickening(~8μm/s)and dislocation slip(4μm/s)results in premature brittle fracture,during the linear hardening and DBT.Moreover,the secondary phases degrade the mechanical property of SAC305 solder alloy,and micro-cracks appear between Cu_(6)Sn_(5)and Ag_(3)Sn in the eutectic matrix.
基金support from National Natural Science Foundation of China(NSFC,Grant numbers U22A20185,U21A20128,52175302 and 52305353)Aeronautical Science Foundation(ASFC-20230036077001)Fundamental Research Funds for the Central Universities(2022FRFK060009,HIT.DZI1.2023012).
文摘The excellent irradiation resistance,high strength and plasticity exhibited by high-entropy alloys(HEAs)make it candidate for engin-eering applications.Diffusion bonding of Al_(0.3)CoCrFeNi single-phase HEAs was carried out using electric-assisted diffusion bonding(EADB),and the effect of bonding temperature on the evolution of the interfacial microstructure and the mechanical properties was investigated.The results indicate that as the bonding temperature increases,the pores at the interface gradually decrease in size and undergo closure.The electric current significantly promotes the pore closure mechanism dominated by plastic deformation at the diffusion interface and promotes the recrystallisation behavior at the interface,and the fracture mode changes from intergranular fracture at the interface to jagged fracture along the grains spanning the weld parent material.Due to the activation effect of EADB,higher-strength diffusion bonding of high-entropy alloys can be achieved at the same temperature compared with the conventional hot-pressure diffusion bonding(HPDB)process.
基金The National Key Research and Development Program of China(No.2023YFC3805003)。
文摘To quantify the seismic resilience of buildings,a method for evaluating functional loss from the component level to the overall building is proposed,and the dual-parameter seismic resilience assessment method based on postearthquake loss and recovery time is improved.A threelevel function tree model is established,which can consider the dynamic changes in weight coefficients of different category of components relative to their functional losses.Bayesian networks are utilized to quantify the impact of weather conditions,construction technology levels,and worker skill levels on component repair time.A method for determining the real-time functional recovery curve of buildings based on the component repair process is proposed.Taking a three-story teaching building as an example,the seismic resilience indices under basic earthquakes and rare earthquakes are calculated.The results show that the seismic resilience grade of the teaching building is comprehensively judged as GradeⅢ,and its resilience grade is more significantly affected by postearthquake loss.The proposed method can be used to predict the seismic resilience of buildings prior to earthquakes,identify weak components within buildings,and provide guidance for taking measures to enhance the seismic resilience of buildings.
基金supported by the Industrial Innovation Major Technology Global Unveiling Project of Jining City(2022JBZP004)Taishan Scholars Project.
文摘Laser twin-arc GTAW(LTA-GTAW)process has been developed by using the synergic interaction effects of laser and a coupled arc in a weld pool to achieve higher energy efficiency.In this study,bead-on-plate welding was conducted on 8-mm-thick Q235B work-pieces to investigate the variation of hybrid arc profile,the influence of hybrid arc profile on weld forming,microstructure and mech-anical properties of the joint during the LTA-GTAW process.The influence of Laser-GTAW and LTA-GTAW methods on weld surface appearance,heat input per unit length,and weld metal microstructure were also demonstrated systematically.The LTA-GTAW can make the distribution of arc energy more reasonable in welding depth and width.When defocus is 0,I_(f)is 330 A,I_(b)is 240 A,laser power is 2.4 kW,and spacing between heat sources of tungsten electrode is 10 mm,the weld shape is better.Compared with Laser-GTAW,LTA-GTAW can achieve lower heat input at the same penetration depth,and the microstructure of the weld is refined.The tensile strength of the welded joint is 121.8%of the base material,and the fracture mode of the welded joint is ductile fracture,the comprehensive mechanical properties are better.
基金Funded by the National Natural Science Foundation of China(No.51878227)。
文摘Microstructures and properties of mortar using ammonium phosphate and potassium phosphate were tested and compared in this case.Moreover,two cementitious additions and two lightweight aggregates,including fly ash,redispersible latex powder,ceramsite sand,and rubber powder,were respectively tried to be applied in magnesium ammonium phosphate cement mortar in order to modify the microstructures and properties.The experimental results show that potassium phosphate is not suitable for magnesium phosphate cement mortar for cold region construction purpose.Although fly ash can bring positive modification in the condition of normal temperature curing,it brings negative effects in the condition of sub-zero temperature curing.Either redispersible latex powder or ceramsite sand can improve the freeze-thaw cycling resistance of magnesium phosphate cement mortar in the conditions of low temperature coupled with freeze-thaw cycling,but only the ceramsite sand can improve both mechanical properties and freeze-thaw cycling resistance.The modification caused by ceramsite sand is mainly due to the exceptional bonding strength between hardened cement paste and the porous surface of ceramsite and the porous structure of ceramsite for the release of frost heave stress.
基金supported by National Natural Science Foundation of China(52175305)National Natural Science Foundation of China(U22B20127)Taishan Scholars Project(tstp20230618).
文摘In this study,the rotary movement of the tungsten needle in gas tungsten arc welding(GTAW)process was realized by direct current motor.The arc characteristics,the flow of molten pool and the microstructure and properties of the weld bead were studied.The results showed that the rotary motion of the tungsten needle transferred circumferential momentum to the arc as well as the molten pool,thereby conferring the latter with rotating fluid flow characteristics.Under the action of a relatively spiraling shielding gas,arc constriction occurred,and molten pool width dropped considerably.A finer and more uniform precipitated phase in the matrix,as well as a fewer large-medium pores,were achieved in the 5A06 aluminum alloy weld metal using this modified GTAW process,which noticeably increased the bending strength and tensile strength of weld metal and the microhardness of fusion zone.
基金the support by the Harbin Manufacturing Science and Technology Innovation Talent Project(No.2023CXRCGD035)the Open Research Foundation of State Key Laboratory of Digital Manufacturing Equipment and Technology in Huazhong University of Science and Technology,China(No.IMETKF2023012).
文摘While laser surface texturing(LST)is a promising manufacturing technique for surface functionalization,simultaneously realizing high precision and high efficiency in the LST of complex curved surface is challenging,due to continuously varied geometries of laser-matter incidence.In the present work,we propose a novel manufacturing system of 7-axis on-the-fly LST for complex curved surface,based on the integrated synchronization of 5-axis linkage motion platform with 2-axis galvanometer.Specifically,the algorithm for decomposing spatial texture trajectory on curved surface into low-frequency and high-frequency parts is established,based on which the kinematic model of synchronized 7-axis system is developed to derive the motion of each axis in both 5-axis linkage motion platform and 2-axis galvanometer simultaneously.Subsequently,the synchronized 7-axis LST system is experimentally realized,including the setup of mechanical stages integrated with optical path,the configuration of numerical control unit,and the development of processing software.Finally,case study of 7-axis on-the-fly LST of freeform aluminum surface is performed,and the advantages in terms of processing efficiency and texturing accuracy over 5-axis linkage LST are demonstrated.The correlation of reduced following errors between mechanical stages with the promoted performance of curved surface texturing by the 7-axis on-the-fly LST is further analyzed.Current work provides a feasible solution for establishing the manufacturing system for high performance LST of complex curved surface.
基金supported by National Key Research&Development Program of China(Grant Nos.2021YFB3703300,2021YFE010016 and 2020YFA0405900)National Natural Science Foundation(Grant Nos.52220105003 and 51971075)+2 种基金the Fundamental Research Funds for the Central Universities(Grant No.FRFCU5710000918)Natural Science Foundation of Heilongjiang Province-Outstanding Youth Fund(Grant No.YQ2020E006)JSPS KAKENHI(Grant No.JP21H01669).
文摘High thermal conductivity and high strength Mg-1.5Mn-2.5Ce alloy with a tensile yield strength of 387.0 MPa,ultimate tensile strength of 395.8 MPa,and thermal conductivity of 142.1 W/(m·K)was successfully fabricated via hot extrusion.The effects of La and Ce additions on the microstructure,thermal conductivity,and mechanical properties of the Mg-1.5Mn alloy were investigated.The results indicated that both the as-extruded Mg-1.5Mn-2.5La and Mg-1.5Mn-2.5Ce alloys exhibited a bimodal grain structure,with dynamically precipitated nano-scaleα-Mn phases.In comparison with La,the addition of Ce enhanced the dynamic precipitation more effectively during hot extrusion,while its influence on promoting the dynamic recrystallization was relatively weaker.The high tensile strength obtained in the as-extruded Mg-1.5Mn-2.5RE alloys can be attributed to the combined influence of the bimodal grain structure(with fine dynamic recrystallized(DRXed)grain size and high proportion of un-dynamic recrystallized(unDRXed)grains),dense nano-scale precipitates,and broken Mg12RE phases,while the remarkable thermal conductivity was due to the precipitation of Mn-rich phases from the Mg matrix.
