In order to improve the consistency between the recommended retrieval results and user needs,improve the recommendation efficiency,and reduce the average absolute deviation of resource retrieval,a design method of int...In order to improve the consistency between the recommended retrieval results and user needs,improve the recommendation efficiency,and reduce the average absolute deviation of resource retrieval,a design method of intelligent recommendation retrieval model for Fujian intangible cultural heritage digital archive resources based on knowledge atlas is proposed.The TG-LDA(Tag-granularity LDA)model is proposed on the basis of the standard LDA(Linear Discriminant Analysis)model.The model is used to mine archive resource topics.The Pearson correlation coefficient is used to measure the relevance between topics.Based on the measurement results,the FastText deep learning model is used to achieve archive resource classification.According to the classification results,TF-IDF(term frequency–inverse document frequency)algorithm is used to calculate the weight of resource retrieval keywords to achieve resource retrieval,and a recommendation model of intangible cultural heritage digital archives resources is built through the knowledge map to achieve comprehensive and personalized recommendation of resources.The experimental results show that the recommendation and retrieval results of the proposed method are more in line with users’needs,can provide users with personalized digital archive resources,and the average absolute deviation of resource retrieval is low,the recommendation efficiency is high,and the utilization effect of archive resources is effectively improved.展开更多
On January 1,2021,the newly revised Archives Law of the People's Republic of China(hereinafter referred to as the new Archives Law)was officially implemented,providing legal protection for archive management,archi...On January 1,2021,the newly revised Archives Law of the People's Republic of China(hereinafter referred to as the new Archives Law)was officially implemented,providing legal protection for archive management,archive work and archive undertaking in the new era.Starting from the relevant provisions of the new Archives Law,the collection of precious meteorological archives was discussed,and it is believed that only on the basis of clarifying the definition,collection responsibility subject,collection scope,ways and methods of precious meteorological archives can the relevant units be convenient to practice and obtain substantive collection effect.展开更多
The purpose of introducing blockchain into electronic archives sharing and utilization is to break the information barrier between electronic archives sharing departments by relying on technologies such as smart contr...The purpose of introducing blockchain into electronic archives sharing and utilization is to break the information barrier between electronic archives sharing departments by relying on technologies such as smart contract and asymmetric encryption.Aiming at the problem of dynamic permission management in common access control methods,a new access control method based on smart contract under blockchain is proposed,which improves the intelligence level under blockchain technology.Firstly,the Internet attribute access control model based on smart contract is established.For the dynamic access of heterogeneous devices,the management contract,permission judgment contract and access control contract are designed;Secondly,the access object credit evaluation algorithm based on particle swarm optimization radial basis function(PSO-RBF)neural network is used to dynamically generate the access node credit threshold combined with the access policy,so as to realize the intelligent access right management method.Finally,combined with the abovemodels and algorithms,the workflow of electronic archives sharing and utilization model of multi blockchain is constructed.The experimental results show that the timeconsuming of the process increases linearly with the number of continuous access to electronic archives blocks,and the secure access control of sharing and utilization is feasible,secure and effective.展开更多
The products of an archival culture in colleges and universities are the final result of the development of archival cultural resources,and the development of archival cultural effects in colleges and universities sho...The products of an archival culture in colleges and universities are the final result of the development of archival cultural resources,and the development of archival cultural effects in colleges and universities should be an important part of improving the artistic level of libraries.The existing RippleNet model doesn’t consider the influence of key nodes on recommendation results,and the recommendation accuracy is not high.Therefore,based on the RippleNet model,this paper introduces the influence of complex network nodes into the model and puts forward the Cn RippleNet model.The performance of the model is verified by experiments,which provide a theoretical basis for the promotion and recommendation of its cultural products of universarchives,solve the problem that RippleNet doesn’t consider the influence of key nodes on recommendation results,and improve the recommendation accuracy.This paper also combs the development course of archival cultural products in detail.Finally,based on the Cn-RippleNet model,the cultural effect of university archives is recommended and popularized.展开更多
With the development and progress of economic construction and market economy,urban construction is also developing rapidly.In the field of construction engineering,a large number of construction engineering files are...With the development and progress of economic construction and market economy,urban construction is also developing rapidly.In the field of construction engineering,a large number of construction engineering files are constantly being produced and accumulated.Therefore,the role of file management is becoming more and more important.The archives are the true records of the whole process of project construction,including the information on the whole process from project design to completion,and are also the main basis for operation management after project delivery.However,there are many aspects to construction project archives,and there are many problems.Nowadays,the classification and preservation of archives are receiving more and more attention.In this article,the origin and development history of construction project archives is first expounded,and its attributes and importance are analyzed.Secondly,the differences between ancient and modern archives management are compared,and at the same time suggestions on improving the archives’traceability system,strengthening the use of archives,and establishing and improving archives management are given.In this paper,we summarize the problems in archives sorting and put forward specific solutions to improve the standardization and systematic management of archives work and enhance the authenticity and integrity of construction project archives.展开更多
To improve the level of informatization of university library archives management,the problems existing in the information construction of university library archives management are analyzed and some practical solutio...To improve the level of informatization of university library archives management,the problems existing in the information construction of university library archives management are analyzed and some practical solutions are proposed in this paper.These solutions can effectively reduce the investment in human resources and equipment and facilities and improve the utilization rate of resources for computer application of university library archives management.展开更多
China’s economy has been developing rapidly in recent years,leading to an acceleration of urbanization,which in turn caused the number of construction projects in various regions to increase significantly.Archives ar...China’s economy has been developing rapidly in recent years,leading to an acceleration of urbanization,which in turn caused the number of construction projects in various regions to increase significantly.Archives are important information for construction projects.The quality of archives management can have a great impact on the quality and economic benefits of construction projects.For this reason,it is necessary to increase the emphasis on archives management of construction projects and take effective management measures.This article introduces the concept of construction project archives,highlights the significance of effective management in construction project archives,and examines prevalent issues along with practical measures to enhance construction project archives management,with the goal of offering valuable insights for archive managers.展开更多
In this paper,an integrated estimation guidance and control(IEGC)system is designed based on the command filtered backstepping approach for circular field-of-view(FOV)strapdown missiles.The threedimensional integrated...In this paper,an integrated estimation guidance and control(IEGC)system is designed based on the command filtered backstepping approach for circular field-of-view(FOV)strapdown missiles.The threedimensional integrated estimation guidance and control nonlinear model with limited actuator deflection angle is established considering the seeker's FOV constraint.The boundary time-varying integral barrier Lyapunov function(IBLF)is employed in backstepping design to constrain the body line-of-sight(BLOS)in IEGC system to fit a circular FOV.Then,the nonlinear adaptive controller is designed to estimate the changing aerodynamic parameters.The generalized extended state observer(GESO)is designed to estimate the acceleration of the maneuvering targets and the unmatched time-varying disturbances for improving tracking accuracy.Furthermore,the command filters are used to solve the"differential expansion"problem during the backstepping design.The Lyapunov theory is used to prove the stability of the overall closed-loop IEGC system.Finally,the simulation results validate the integrated system's effectiveness,achieving high accuracy strikes against maneuvering targets.展开更多
Aimming at the difficulty in getting semantic informarton from each problem in problem set archives, We propose a new method of ontology based semantic annotation for problem set archives, which utilizes programming k...Aimming at the difficulty in getting semantic informarton from each problem in problem set archives, We propose a new method of ontology based semantic annotation for problem set archives, which utilizes programming knowledge domain ontology to add semantic annotations to problems in the Web. The system we developed adds semantic annotation for each problem in the form of Extensible Makeup Language. Our method overcomes the difficulty of extracting semantics from problem set archives and the efficiency of this method is demonstrated through a case study. Having semantic annotations of problems, a student can efficiently locate the problems that logically corre spond to his knowledge.展开更多
The Trusted Platform Module (TPM) is a dedicated hardware chip designed to provide a higher level of security for computing platform. All TPM functionalities are implemented in TPM corntrends to achieve specific sec...The Trusted Platform Module (TPM) is a dedicated hardware chip designed to provide a higher level of security for computing platform. All TPM functionalities are implemented in TPM corntrends to achieve specific security goals. We attempt to analyze the security properties of these commands, especially the key management API. Our study utilizes applied pi calculus to forrmlize the commands and determine how their security properties affect TPM key rmnagement. The attacker is assumed to call TPM comrmnds without bounds and without knowing the TPM root key, expecting to obtain or replace the user key. The analysis goal in our study is to guarantee the corre- sponding property of API execution and the integrity of API data. We analyze the security properties of TPM commands with a process reduction method, identify the key-handle hijack attack on a TPM newly created key, and propose reasonable solutions to solve the problem. Then, we conduct an experiment involving a key-handle attack, which suc- cessfully replaces a user key with an attacker's key using lmlicious TPM software. This paper discloses the weakness of the relationship between the key handle and the key object. After the TPM software stack is compromised, the attacker can hunch a keyhandle attack to obtain the user key and even break into the whole storage tree of user keys.展开更多
High concentrations of environmental fungi in the archives repositories are dangerous for the documents preserved in those places and for the workers'health.The aims of this work were to evaluate the behavior of t...High concentrations of environmental fungi in the archives repositories are dangerous for the documents preserved in those places and for the workers'health.The aims of this work were to evaluate the behavior of the fungal concentration and diversity in the indoor air of repositories of 3 archives located in Havana,Cuba,and to demonstrate the potential risk that these taxa represent for the documentary heritage preserved in these institutions.The indoor and outdoor environments were sampled with a biocollector.From the I/O ratios,it was evident that two of the studied archives were not contaminated,while one of them did show contamination despite having temperature and relative humidity values very similar to the other two.Aspergillus,Penicillium and Cladosporium were the predominant genera in the indoor environments.New finds for archival environments were the genera Harposporium and Scolecobasidium.The principal species classified ecologically as abundant were C.cladosporioides and P.citrinum.They are known as opportunistic pathogenic fungi.All the analyzed taxa excreted acids,the most of them degraded cellulose,starch and gelatin while about 48%excreted different pigments.But 33%of them showed the highest biodeteriogenic potential,evidencing that they are the most dangerous for the documentary collections.展开更多
In order to better promote the digital and electronic development of libraries,this paper first analyzes the management requirements of library archives,constructs a management mode based on electronic technology,and ...In order to better promote the digital and electronic development of libraries,this paper first analyzes the management requirements of library archives,constructs a management mode based on electronic technology,and analyzes the management measures of electronic library archives for reference.展开更多
In the field of medical equipment and equipment storage work, when we access accessories and equipment, due to the actual conditions, it causes low efficiency. It is often difficult to quickly and efficiently search b...In the field of medical equipment and equipment storage work, when we access accessories and equipment, due to the actual conditions, it causes low efficiency. It is often difficult to quickly and efficiently search by using simple data management software, such as excel. In order to solve the problem, our team used Python development tool to build high-performance retrieval software, which enabled the equipment custodian to maintain or redesign the database according to actual needs. Through actual verification, this system not only can greatly improve the accuracy of device access, but also has good expansion portability, which could manage various multimedia data systems.展开更多
Deeply subducted lithospheric slabs may reach to the mantle transition zone(MTZ,410-660 km depth)or even to the core–mantle boundary(CMB)at depths of^2900km.Our knowledge of the fate of subducted surface material at ...Deeply subducted lithospheric slabs may reach to the mantle transition zone(MTZ,410-660 km depth)or even to the core–mantle boundary(CMB)at depths of^2900km.Our knowledge of the fate of subducted surface material at the MTZ or near the CMB is poor and based mainly on the tomography data and laboratory experiments through indirect methods.Limited data come from the samples of deep mantle diamonds and their mineral inclusions obtained from kimberlites and associated rock assemblages in old cratons.We report in this presentation new data and observations from diamonds and other UHP minerals recovered from ophiolites that we consider as a new window into the life cycle of deeply subducted oceanic and continental crust.Ophiolites are fragments of ancient oceanic lithosphere tectonically accreted into continental margins,and many contain significant podiform chromitites.Our research team has investigated over the last 10 years ultrahigh-pressure and super-reducing mineral groups discovered in peridotites and/or chromitites of ophiolites around the world,including the Luobusa(Tibet),Ray-Iz(Polar Urals-Russia),and 12 other ophiolites from 8orogenic belts in 5 different countries(Albania,China,Myanmar,Russia,and Turkey).High-pressure minerals include diamond,coesite,pseudomorphic stishovite,qingsongite(BN)and Ca-Si perovskite,and the most important native and highly reduced minerals recovered to date include moissanite(Si C),Ni-Mn-Co alloys,Fe-Si and Fe-C phases.These mineral groups collectively confirm extremely high?pressures(300 km to≥660 km)and super-reducing conditions in their environment of formation in the mantle.All of the analyzed diamonds have unusually light carbon isotope compositions(δ13C=-28.7 to-18.3‰)and variable trace element contents that*d i stinguish them from most kimberlitic and UHPmetamorphic varieties.The presence of exsolution lamellae of diopside and coesite in some chromite grains suggests chromite crystallization depths around>380 km,near the mantle transition zone.The carbon isotopes and other features of the high-pressure and super-reduced mineral groups point to previously subducted surface material as their source of origin.Recycling of subducted crust in the deep mantle may proceed in three stages:Stage 1–Carbon-bearing fluids and melts may have been formed in the MTZ,in the lower mantle or even near the CMB.Stage 2–Fluids or melts may rise along with deep plumes through the lower mantle and reach the MTZ.Some minerals,such as diamond,stishovite,qingsongite and Ca-silicate perovskite can precipitate from these fluids or melts in the lower mantle during their ascent.Material transported to the MTZ would be mixed with highly reduced and UHP phases,presumably derived from zones with extremely low f O2,as required for the formation of moissanite and other native elements.Stage 3–Continued ascent above the transition of peridotites containing chromite and ultrahigh-pressure minerals transports them to shallow mantle depths,where they participate in decompressional partial melting and oceanic lithosphere formation.The widespread occurrence of ophiolite-hosted diamonds and associated UHP mineral groups suggests that they may be a common feature of in-situ oceanic mantle.Because mid-ocean ridge spreading environments are plate boundaries widely distributed around the globe,and because the magmatic accretion of oceanic plates occurs mainly along these ridges,the on-land remnants of ancient oceanic lithosphere produced at former mid-ocean ridges provide an important window into the Earth’s recycling system and a great opportunity to probe the nature of deeply recycled crustal material residing in the deep mantle展开更多
文摘In order to improve the consistency between the recommended retrieval results and user needs,improve the recommendation efficiency,and reduce the average absolute deviation of resource retrieval,a design method of intelligent recommendation retrieval model for Fujian intangible cultural heritage digital archive resources based on knowledge atlas is proposed.The TG-LDA(Tag-granularity LDA)model is proposed on the basis of the standard LDA(Linear Discriminant Analysis)model.The model is used to mine archive resource topics.The Pearson correlation coefficient is used to measure the relevance between topics.Based on the measurement results,the FastText deep learning model is used to achieve archive resource classification.According to the classification results,TF-IDF(term frequency–inverse document frequency)algorithm is used to calculate the weight of resource retrieval keywords to achieve resource retrieval,and a recommendation model of intangible cultural heritage digital archives resources is built through the knowledge map to achieve comprehensive and personalized recommendation of resources.The experimental results show that the recommendation and retrieval results of the proposed method are more in line with users’needs,can provide users with personalized digital archive resources,and the average absolute deviation of resource retrieval is low,the recommendation efficiency is high,and the utilization effect of archive resources is effectively improved.
基金Supported by the Key Research and Development Planning Project of Anhui Province(2022h11020002).
文摘On January 1,2021,the newly revised Archives Law of the People's Republic of China(hereinafter referred to as the new Archives Law)was officially implemented,providing legal protection for archive management,archive work and archive undertaking in the new era.Starting from the relevant provisions of the new Archives Law,the collection of precious meteorological archives was discussed,and it is believed that only on the basis of clarifying the definition,collection responsibility subject,collection scope,ways and methods of precious meteorological archives can the relevant units be convenient to practice and obtain substantive collection effect.
基金supported by Shandong Social Science Planning and Research Project in 2021(No.21CPYJ40).
文摘The purpose of introducing blockchain into electronic archives sharing and utilization is to break the information barrier between electronic archives sharing departments by relying on technologies such as smart contract and asymmetric encryption.Aiming at the problem of dynamic permission management in common access control methods,a new access control method based on smart contract under blockchain is proposed,which improves the intelligence level under blockchain technology.Firstly,the Internet attribute access control model based on smart contract is established.For the dynamic access of heterogeneous devices,the management contract,permission judgment contract and access control contract are designed;Secondly,the access object credit evaluation algorithm based on particle swarm optimization radial basis function(PSO-RBF)neural network is used to dynamically generate the access node credit threshold combined with the access policy,so as to realize the intelligent access right management method.Finally,combined with the abovemodels and algorithms,the workflow of electronic archives sharing and utilization model of multi blockchain is constructed.The experimental results show that the timeconsuming of the process increases linearly with the number of continuous access to electronic archives blocks,and the secure access control of sharing and utilization is feasible,secure and effective.
文摘The products of an archival culture in colleges and universities are the final result of the development of archival cultural resources,and the development of archival cultural effects in colleges and universities should be an important part of improving the artistic level of libraries.The existing RippleNet model doesn’t consider the influence of key nodes on recommendation results,and the recommendation accuracy is not high.Therefore,based on the RippleNet model,this paper introduces the influence of complex network nodes into the model and puts forward the Cn RippleNet model.The performance of the model is verified by experiments,which provide a theoretical basis for the promotion and recommendation of its cultural products of universarchives,solve the problem that RippleNet doesn’t consider the influence of key nodes on recommendation results,and improve the recommendation accuracy.This paper also combs the development course of archival cultural products in detail.Finally,based on the Cn-RippleNet model,the cultural effect of university archives is recommended and popularized.
文摘With the development and progress of economic construction and market economy,urban construction is also developing rapidly.In the field of construction engineering,a large number of construction engineering files are constantly being produced and accumulated.Therefore,the role of file management is becoming more and more important.The archives are the true records of the whole process of project construction,including the information on the whole process from project design to completion,and are also the main basis for operation management after project delivery.However,there are many aspects to construction project archives,and there are many problems.Nowadays,the classification and preservation of archives are receiving more and more attention.In this article,the origin and development history of construction project archives is first expounded,and its attributes and importance are analyzed.Secondly,the differences between ancient and modern archives management are compared,and at the same time suggestions on improving the archives’traceability system,strengthening the use of archives,and establishing and improving archives management are given.In this paper,we summarize the problems in archives sorting and put forward specific solutions to improve the standardization and systematic management of archives work and enhance the authenticity and integrity of construction project archives.
文摘To improve the level of informatization of university library archives management,the problems existing in the information construction of university library archives management are analyzed and some practical solutions are proposed in this paper.These solutions can effectively reduce the investment in human resources and equipment and facilities and improve the utilization rate of resources for computer application of university library archives management.
文摘China’s economy has been developing rapidly in recent years,leading to an acceleration of urbanization,which in turn caused the number of construction projects in various regions to increase significantly.Archives are important information for construction projects.The quality of archives management can have a great impact on the quality and economic benefits of construction projects.For this reason,it is necessary to increase the emphasis on archives management of construction projects and take effective management measures.This article introduces the concept of construction project archives,highlights the significance of effective management in construction project archives,and examines prevalent issues along with practical measures to enhance construction project archives management,with the goal of offering valuable insights for archive managers.
文摘In this paper,an integrated estimation guidance and control(IEGC)system is designed based on the command filtered backstepping approach for circular field-of-view(FOV)strapdown missiles.The threedimensional integrated estimation guidance and control nonlinear model with limited actuator deflection angle is established considering the seeker's FOV constraint.The boundary time-varying integral barrier Lyapunov function(IBLF)is employed in backstepping design to constrain the body line-of-sight(BLOS)in IEGC system to fit a circular FOV.Then,the nonlinear adaptive controller is designed to estimate the changing aerodynamic parameters.The generalized extended state observer(GESO)is designed to estimate the acceleration of the maneuvering targets and the unmatched time-varying disturbances for improving tracking accuracy.Furthermore,the command filters are used to solve the"differential expansion"problem during the backstepping design.The Lyapunov theory is used to prove the stability of the overall closed-loop IEGC system.Finally,the simulation results validate the integrated system's effectiveness,achieving high accuracy strikes against maneuvering targets.
基金Supported by the National Natural Science Fundationof China (60273051)
文摘Aimming at the difficulty in getting semantic informarton from each problem in problem set archives, We propose a new method of ontology based semantic annotation for problem set archives, which utilizes programming knowledge domain ontology to add semantic annotations to problems in the Web. The system we developed adds semantic annotation for each problem in the form of Extensible Makeup Language. Our method overcomes the difficulty of extracting semantics from problem set archives and the efficiency of this method is demonstrated through a case study. Having semantic annotations of problems, a student can efficiently locate the problems that logically corre spond to his knowledge.
基金This paper was supported by the National Natural Science Foundation of China under Grants No.91118006, No. 61202414 the Knowledge Innovation Project of Chinese Academy of Science under Grant No. ISCAS2009-DR14.
文摘The Trusted Platform Module (TPM) is a dedicated hardware chip designed to provide a higher level of security for computing platform. All TPM functionalities are implemented in TPM corntrends to achieve specific security goals. We attempt to analyze the security properties of these commands, especially the key management API. Our study utilizes applied pi calculus to forrmlize the commands and determine how their security properties affect TPM key rmnagement. The attacker is assumed to call TPM comrmnds without bounds and without knowing the TPM root key, expecting to obtain or replace the user key. The analysis goal in our study is to guarantee the corre- sponding property of API execution and the integrity of API data. We analyze the security properties of TPM commands with a process reduction method, identify the key-handle hijack attack on a TPM newly created key, and propose reasonable solutions to solve the problem. Then, we conduct an experiment involving a key-handle attack, which suc- cessfully replaces a user key with an attacker's key using lmlicious TPM software. This paper discloses the weakness of the relationship between the key handle and the key object. After the TPM software stack is compromised, the attacker can hunch a keyhandle attack to obtain the user key and even break into the whole storage tree of user keys.
文摘High concentrations of environmental fungi in the archives repositories are dangerous for the documents preserved in those places and for the workers'health.The aims of this work were to evaluate the behavior of the fungal concentration and diversity in the indoor air of repositories of 3 archives located in Havana,Cuba,and to demonstrate the potential risk that these taxa represent for the documentary heritage preserved in these institutions.The indoor and outdoor environments were sampled with a biocollector.From the I/O ratios,it was evident that two of the studied archives were not contaminated,while one of them did show contamination despite having temperature and relative humidity values very similar to the other two.Aspergillus,Penicillium and Cladosporium were the predominant genera in the indoor environments.New finds for archival environments were the genera Harposporium and Scolecobasidium.The principal species classified ecologically as abundant were C.cladosporioides and P.citrinum.They are known as opportunistic pathogenic fungi.All the analyzed taxa excreted acids,the most of them degraded cellulose,starch and gelatin while about 48%excreted different pigments.But 33%of them showed the highest biodeteriogenic potential,evidencing that they are the most dangerous for the documentary collections.
文摘In order to better promote the digital and electronic development of libraries,this paper first analyzes the management requirements of library archives,constructs a management mode based on electronic technology,and analyzes the management measures of electronic library archives for reference.
文摘In the field of medical equipment and equipment storage work, when we access accessories and equipment, due to the actual conditions, it causes low efficiency. It is often difficult to quickly and efficiently search by using simple data management software, such as excel. In order to solve the problem, our team used Python development tool to build high-performance retrieval software, which enabled the equipment custodian to maintain or redesign the database according to actual needs. Through actual verification, this system not only can greatly improve the accuracy of device access, but also has good expansion portability, which could manage various multimedia data systems.
文摘Deeply subducted lithospheric slabs may reach to the mantle transition zone(MTZ,410-660 km depth)or even to the core–mantle boundary(CMB)at depths of^2900km.Our knowledge of the fate of subducted surface material at the MTZ or near the CMB is poor and based mainly on the tomography data and laboratory experiments through indirect methods.Limited data come from the samples of deep mantle diamonds and their mineral inclusions obtained from kimberlites and associated rock assemblages in old cratons.We report in this presentation new data and observations from diamonds and other UHP minerals recovered from ophiolites that we consider as a new window into the life cycle of deeply subducted oceanic and continental crust.Ophiolites are fragments of ancient oceanic lithosphere tectonically accreted into continental margins,and many contain significant podiform chromitites.Our research team has investigated over the last 10 years ultrahigh-pressure and super-reducing mineral groups discovered in peridotites and/or chromitites of ophiolites around the world,including the Luobusa(Tibet),Ray-Iz(Polar Urals-Russia),and 12 other ophiolites from 8orogenic belts in 5 different countries(Albania,China,Myanmar,Russia,and Turkey).High-pressure minerals include diamond,coesite,pseudomorphic stishovite,qingsongite(BN)and Ca-Si perovskite,and the most important native and highly reduced minerals recovered to date include moissanite(Si C),Ni-Mn-Co alloys,Fe-Si and Fe-C phases.These mineral groups collectively confirm extremely high?pressures(300 km to≥660 km)and super-reducing conditions in their environment of formation in the mantle.All of the analyzed diamonds have unusually light carbon isotope compositions(δ13C=-28.7 to-18.3‰)and variable trace element contents that*d i stinguish them from most kimberlitic and UHPmetamorphic varieties.The presence of exsolution lamellae of diopside and coesite in some chromite grains suggests chromite crystallization depths around>380 km,near the mantle transition zone.The carbon isotopes and other features of the high-pressure and super-reduced mineral groups point to previously subducted surface material as their source of origin.Recycling of subducted crust in the deep mantle may proceed in three stages:Stage 1–Carbon-bearing fluids and melts may have been formed in the MTZ,in the lower mantle or even near the CMB.Stage 2–Fluids or melts may rise along with deep plumes through the lower mantle and reach the MTZ.Some minerals,such as diamond,stishovite,qingsongite and Ca-silicate perovskite can precipitate from these fluids or melts in the lower mantle during their ascent.Material transported to the MTZ would be mixed with highly reduced and UHP phases,presumably derived from zones with extremely low f O2,as required for the formation of moissanite and other native elements.Stage 3–Continued ascent above the transition of peridotites containing chromite and ultrahigh-pressure minerals transports them to shallow mantle depths,where they participate in decompressional partial melting and oceanic lithosphere formation.The widespread occurrence of ophiolite-hosted diamonds and associated UHP mineral groups suggests that they may be a common feature of in-situ oceanic mantle.Because mid-ocean ridge spreading environments are plate boundaries widely distributed around the globe,and because the magmatic accretion of oceanic plates occurs mainly along these ridges,the on-land remnants of ancient oceanic lithosphere produced at former mid-ocean ridges provide an important window into the Earth’s recycling system and a great opportunity to probe the nature of deeply recycled crustal material residing in the deep mantle