The Moon,as the closest celestial body to the Earth,plays a pivotal role in the progression of deep space exploration,and the establishment of research outposts on its surface represents a crucial step in this mission...The Moon,as the closest celestial body to the Earth,plays a pivotal role in the progression of deep space exploration,and the establishment of research outposts on its surface represents a crucial step in this mission.Lunar lava tubes are special underground caves formed by volcanic eruptions and are considered as ideal natural shelters and scientific laboratories for lunar base construction.This paper begins with an in-depth overview of the geological origins,exploration history,and distribution locations of lunar lava tubes.Subsequently,it delves into the presentation of four distinctive advantages and typical concepts for constructing bases within lava tubes,summarizing the ground-based attempts made thus far in lunar lava tube base construction.Field studies conducted on a lava tube in Hainan revealed rock compositions similar to those found during the Apollo missions and clear lava tube structures,making it a promising analog site.Lastly,the challenges and opportunities encountered in the field of geotechnical engineering regarding the establishment of lunar lava tube bases are discussed,encompassing cave exploration technologies,in-situ testing methods,geomechanical properties under lunar extreme environments,base design and structural stability assessment,excavation and reinforcement techniques,and simulated Earth-based lava tube base.展开更多
The development and utilization of lunar resources are entering a critical stage.Immediate focus is needed on key technologies for in-situ resource utilization(ISRU)and lunar base construction.This paper comparatively...The development and utilization of lunar resources are entering a critical stage.Immediate focus is needed on key technologies for in-situ resource utilization(ISRU)and lunar base construction.This paper comparatively analyzes the basic characteristics of lunar regolith samples returned from Chang'e-5(CE-5),Apollo,and Luna missions,focusing on their physical,mechanical,mineral,chemical,and morphological parameters.Given the limited availability of lunar regolith,more than 50 lunar regolith simulants are summarized.The differences between lunar regolith and simulants concerning these parameters are discussed.To facilitate the construction of lunar bases,this article summarizes the advancements in research on construction materials derived from lunar regolith simulants.Based on statistical results,lunar regolith simulant-based composites are classified into 5 types by their strengthening and toughening mechanisms,and a comprehensive analysis of molding methods,preparation conditions,and mechanical properties is conducted.Furthermore,the potential lunar base construction forms are reviewed,and the adaptability of lunar regolith simulant-based composites and lunar base construction methods are proposed.The key demands of lunar bases constructed with lunar regolith-based composites are discussed,including energy demand,in-situ buildability,service performance,and structural availability.This progress contributes to providing essential material and methodological support for future lunar construction.展开更多
The Fenghua River Bridge is a major structure on the highway between Hengzhang and Guojiachi, which is to be built with a four-span prestress concrete (PC) box girder and symmetrical cantilever castings. In this paper...The Fenghua River Bridge is a major structure on the highway between Hengzhang and Guojiachi, which is to be built with a four-span prestress concrete (PC) box girder and symmetrical cantilever castings. In this paper, a finite element method (FEM) model is set up to study the effects of concrete differential aging time on the construction phases of the Fenghua River Bridge by calculating the vertical displacement of the folding segment of the middle span and the longitudinal bending moment of Pier 12#. In the model, the girders are classified into 150 changing sections based on the desgn scheme, and their construction is to be carried in 16 phases respectively to build 12 blocks connected by a side folding segment and a middle folding segment, covered with a second dead load and in completion for 20 years. It is found that the internal forces and deformations of the concrete structures at the aging time of 60 d are quite different from those of 0 d aging time while the behaviors of the structures of 120 d aging time is nearly the same as those of 60 d aging time― the differences are so small that can be neglected, suggesting that the creep develops obviously about one month after the cement is hardened and the development fades later on.展开更多
As the extension and supplement of explicit curriculum,the English hidden curriculum in higher vocational colleges plays animportant role in cultivating students' behaviors,stimulate their interest and arouse thei...As the extension and supplement of explicit curriculum,the English hidden curriculum in higher vocational colleges plays animportant role in cultivating students' behaviors,stimulate their interest and arouse their enthusiasm,initiative and creativity in learningEnglish.This paper analyzes the problems of English hidden curriculum construction in higher vocational colleges under the back-ground o"fInternet plus",and puts forward some corresponding countermeasures to bring the role of college English hidden curriculuminto full play.展开更多
OBE theory focuses on students’learning outcomes and application ability,which is consistent with the requirements of the new curriculum standard.The paper attempts to apply OBE theory to innovate the construction of...OBE theory focuses on students’learning outcomes and application ability,which is consistent with the requirements of the new curriculum standard.The paper attempts to apply OBE theory to innovate the construction of English classroom teaching mode in senior high schools from aspects of teaching aims,teaching activities,teaching assessments and application activities.Results show that the application of OBE in high schools is beneficial to the development of English teaching and students'learning.展开更多
There have been heated discussions onthere-be construction in the field of linguistics,and linguists have made numerous attempts to explore it in syntax,semantics,and pragmatics.However,researchers have not reached an...There have been heated discussions onthere-be construction in the field of linguistics,and linguists have made numerous attempts to explore it in syntax,semantics,and pragmatics.However,researchers have not reached any consensus.There is a review of the mainstream of the studies to explore what can be done to promote unanimity.展开更多
An assessment index system including environment, socio-culture, economy and technology was established for evaluating environmental construction level of community （objective construction）, and questionnaire was de...An assessment index system including environment, socio-culture, economy and technology was established for evaluating environmental construction level of community （objective construction）, and questionnaire was designed according to paper review for evaluating residential satisfaction （subjective satisfaction）. The index system was divided into four layers： system （A）, subsystems （B）, categories （C）, and indicators （D）, and in total of 38 indicators was established. The Xihe community, affiliated to Nanfen district, Benxi City, Liaoning Province, China was selected as a case study. Results indicated that the community sustainability index related to objective environmental construction was 0.4355 and was classified as class Ⅲ （moderate）; the community sustainability index related to the residential satisfaction was 0.4255, belonging to class Ⅲ. In conclusion, the sustainability of Xihe community was moderate and needed to be improved. Residential satisfaction was lower than objective environmental construction. The assessment index system established in this study is able to reflect the comprehensive sustainability of community and can be used to evaluate other similar communities＇ sustainability.展开更多
In the circle of linguistics,numerous attempts have been made to explore there-be construction in the fields of syntax,semantics,and pragmatics,but in the by-now researches there is little touching on the derivation o...In the circle of linguistics,numerous attempts have been made to explore there-be construction in the fields of syntax,semantics,and pragmatics,but in the by-now researches there is little touching on the derivation of the word there.In consequence,herein the focus and effort are put on the derivation of there.It explores the motivation behind the derivation of there based on the cognitive study on there constructions.It is demonstrated that there-be construction derivates to meet the need of the development of human cognitive capacities of expressing abstract mental space.It is mainly motivated by gestalt law,figure-ground theory.展开更多
M.Butterfly,written by David Henry Hwang,is one of the most influential plays in contemporary American dramatic his-tory.Hwang incorporates a stereotypical fantasy into his play,involving conflicts and misunderstandin...M.Butterfly,written by David Henry Hwang,is one of the most influential plays in contemporary American dramatic his-tory.Hwang incorporates a stereotypical fantasy into his play,involving conflicts and misunderstandings between the East and theWest,between men and women.Through the analysis of the construction of the Orientalist"Madame Butterfly Fantasy"in M.Butterfly,this paper analyzes sexual prejudice and racial bias embedded in the"Fantasy".展开更多
According to the definition of tense,English has no actual future tense.The ways to express future time in English vary with the specific situation.We should avoid frequently using the same way to express the future.I...According to the definition of tense,English has no actual future tense.The ways to express future time in English vary with the specific situation.We should avoid frequently using the same way to express the future.It is important to study the different construction of the future time in English and its implications in order to make it clear that the appropriate construction to cope with the specific situation should be noticed.展开更多
Empty categories,which lack phonological form and hence are not visible in the phonetic representation of the sentence,have both syntactic and semantic properties.Null subjects PRO and pro are base-generated empty cat...Empty categories,which lack phonological form and hence are not visible in the phonetic representation of the sentence,have both syntactic and semantic properties.Null subjects PRO and pro are base-generated empty categories.This thesis,based on Chomsky's theory about empty categories and research achievements made by Chinese scholars,attempts to analyze the liandong(Serial Verb) construction from Figure and Ground perspective.展开更多
In the era of"Internet Plus",emphasis has been placed on construction of teaching resources by utilizing internet platform andtechnologies.It is of great significance to discuss the construction of English t...In the era of"Internet Plus",emphasis has been placed on construction of teaching resources by utilizing internet platform andtechnologies.It is of great significance to discuss the construction of English teaching resources in higher vocational colleges from theperspective of ecopedagogy which is characterized by openness and diversity.We can achieve high efficiency and effectiveness in con-structing English teaching resources for higher vocational college students through abiding by following principles such as diversity,de-velopment,adaptation and openness.展开更多
English ditransitive construction is a significant component of Goldberg's construction grammar which is based on cognitive linguistics. It aims to enlighten teachers and learners of SLA. It presents backgrounds a...English ditransitive construction is a significant component of Goldberg's construction grammar which is based on cognitive linguistics. It aims to enlighten teachers and learners of SLA. It presents backgrounds and the basic concepts of Goldberg's construction grammar, depicts what English ditransitive construction is and its semantic constraints, and refers to enlightments of English ditransitive construction on SLA from four perspectives.展开更多
Since the Keyser and Roeper,English middle construction(EMC)has attracted the linguists successfully with its complex syntactic and semantic features.The essential feature of EMC is active in syntactic form and passiv...Since the Keyser and Roeper,English middle construction(EMC)has attracted the linguists successfully with its complex syntactic and semantic features.The essential feature of EMC is active in syntactic form and passive in semantic meaning.Semantically,EMC is characterized by non-eventivity,genericity,agentivity and modality.Syntactically,the argument of EMC sentence is the internal argument of the verb,and the verb usually takes the modifier of an adverb or modal verb.Due to the complexity of EMC,many English learners encounter some difficulties in learning the second language.Based on Construction Grammar,this paper mainly investigates the following questions:first,is the learners’acquisition on EMC related to their English proficiency?Second,for typical and untypical EMC,which one is more difficult for them to learn?According to the research objectives,the research finally selects 32 valid papers and divides the subjects into advanced and elementary groups according to their scores in CET-6 and TEM-8,and R Studio is adopted to analyze their acquisition of EMC.The research results show that:first,the learners’acquisition on EMC is related to their English proficiency.Second,for typical and untypical EMC,both of them acquire typical EMC better than the untypical one,so the typical EMC is more difficult for the them to learn.展开更多
The recent research progress of structure- and size-controlled micro/nano-energetic materials is reviewed, which properties are fundamentally different from those of their corresponding bulk materials. The development...The recent research progress of structure- and size-controlled micro/nano-energetic materials is reviewed, which properties are fundamentally different from those of their corresponding bulk materials. The development of the construction strategies for achieving zero-dimensional (0D), one-dimensional (1D), two-dimensional (2D), and three-dimensional (3D) micro/nanostructures from energetic molecules is introduced. Also, an overview of the unique properties induced by micro/nanostructures and size effects is provided. Special emphasis is focused on the size-dependent properties that are different from those of the conventional micro-sized energetic materials, such as thermal decomposition, sensitivity, combustion and detonation, and compaction behaviors. A conclusion and our view of the future development of micro/nano-energetic materials and devices are given.展开更多
Attribute-based encryption is drawing more attention with its inherent attractive properties which are potential to be widely used in the newly developing cloud computing. However, one of the main obstacles for its ap...Attribute-based encryption is drawing more attention with its inherent attractive properties which are potential to be widely used in the newly developing cloud computing. However, one of the main obstacles for its application is how to revoke the attributes of the users, though some ABE schemes have realized revocation, they mostly focused on the user revocation that revokes the user＇s whole attributes, or attribute revocation under the indirect revocation model such that all the users＇ private keys will be affected by the revocation. In this paper, we define the model of CP-ABE supporting the attribute revocation under the direct revocation model, in which the revocation list is embed in the ciphertext and none of the users＇ private keys will be affected by the revocation process. Then we propose a generic construction, and prove its security with the decision q-BDHE assumption.展开更多
MXenes are a family of two-dimensional (2D) transition metal carbides, carbonitrides/nitrides with superior physical and chemical properties, which have attracted extensive attention since the discovery in 2011. The i...MXenes are a family of two-dimensional (2D) transition metal carbides, carbonitrides/nitrides with superior physical and chemical properties, which have attracted extensive attention since the discovery in 2011. The impressive electrochemical activity of MXene makes it one of the most potential electrode materials in rechargeable batteries and supercapacitors. However, single-component MXene electrodes are difficult to achieve high specific capacity, efficient ion/electron transport, and high stability compatibility in an electrochemical environment. Studies have shown that it is an effective method to introduce nanomaterials between MXene layers to construct heterostructures and to improve the electrochemical performance through the synergistic effect among the components in the heterostructures. The introduction of nanomaterials can effectively suppress the restacking of MXene nanosheets, shorten the diffusion path of ions and promote the electrolyte transport, which is beneficial to enhance the rate performance of MXene;moreover, the excellent mechanical flexibility of MXene can reduce the volume expansion of nanomaterials during charge/discharge, thereby effectively protecting the integrity of the electrode structure and improving the cycling stability. Therefore, in this review, combined with theoretical calculations, we summarize the recent advances of MXene heterostructures in terms of synthesis strategies and energy storage applications, including supercapacitors, metal-ions batteries (Li, Na, K, Mg, Zn, Al) and metal anode protection. Furthermore, potential challenges and application perspectives for MXene heterostructures are also outlined.展开更多
In the Davey-MacKay(DM) construction,the inner decoder treats unknown transmitted bits as random independent substitution errors. It limits the synchronization capability of the inner decoder, and thus weakens the err...In the Davey-MacKay(DM) construction,the inner decoder treats unknown transmitted bits as random independent substitution errors. It limits the synchronization capability of the inner decoder, and thus weakens the error-correcting capability of the DM construction.In order to improve the performance of the DM construction, an iterative decoding scheme is proposed, which iteratively utilizes the more accurate estimates of transmitted codewords. In the proposed scheme, the estimated average bit error rates and the estimated low-density parity-check(LDPC) codewords from the outer decoder are fed back into the inner decoder to update the synchronization process. Simulation results show that the proposed iterative decoding scheme significantly outperforms the traditional DM construction.展开更多
Abstract： The layered decoding algorithm has been widely used in the implementation of Low Density Parity Check （LDPC） decoders, due to its high convergence speed. However, the pipeline operation of the layered dec...Abstract： The layered decoding algorithm has been widely used in the implementation of Low Density Parity Check （LDPC） decoders, due to its high convergence speed. However, the pipeline operation of the layered decoder may introduce memory access conflicts, which heavily deteriorates the decoder throughput. To essentially deal with the issue of memory access conflicts,展开更多
A novel particle/metal-based monolithic catalysts dual-bed reactor with beds-interspace supplementary oxygen is constructed comprising of the upper-layer 5 wt%Na2WO4-2 wt%Mn/SiO2 particle catalyst and the under-layer ...A novel particle/metal-based monolithic catalysts dual-bed reactor with beds-interspace supplementary oxygen is constructed comprising of the upper-layer 5 wt%Na2WO4-2 wt%Mn/SiO2 particle catalyst and the under-layer 3 wt%Ce-5 wt%Na2WO4-2 wt%Mn/SBA-15/Al2O3/FeCrA1 metal-based monolithic catalyst as well as a side tube in the interspaces of two layers for supplementing 02. The reaction performance of oxidative coupling of methane （OCM） in the dual-bed reactor system is evaluated. The effects of the reaction parameters such as feed CH4/O2 ratio, reaction temperature and side tube feed 02 flowrate on the catalytic performance are investigated. The results indicate that the suggested mode of dual-bed reactor exhibits an excellent performance for OCM. CH4 conversion of 33.2%, C2H4 selectivity of 46.5% and C2 yield of 22.5% could be obtained, which have been increased by 6.4%, 4.1% and 5.5%, respectively, as compared with 5 wt%Na2WO4-2 wt%Mn/SiO2 particle catalyst in a single-bed reactor and increased by 10.7%, 31.9% and 17.7%, respectively, as compared with 3 wt%Ce-5 wt%Na2WO4-2 wt%Mn/SBA-15/Al2O3/FeCrA1 metal-based monolithic catalyst in a single-bed reactor. The effective promotion of OCM performance in the reactor would supply a valuable reference for the industrialization of OCM process.展开更多
基金supported by the National Natural Science Foundation of China(Nos.52125903 and 52339001).
文摘The Moon,as the closest celestial body to the Earth,plays a pivotal role in the progression of deep space exploration,and the establishment of research outposts on its surface represents a crucial step in this mission.Lunar lava tubes are special underground caves formed by volcanic eruptions and are considered as ideal natural shelters and scientific laboratories for lunar base construction.This paper begins with an in-depth overview of the geological origins,exploration history,and distribution locations of lunar lava tubes.Subsequently,it delves into the presentation of four distinctive advantages and typical concepts for constructing bases within lava tubes,summarizing the ground-based attempts made thus far in lunar lava tube base construction.Field studies conducted on a lava tube in Hainan revealed rock compositions similar to those found during the Apollo missions and clear lava tube structures,making it a promising analog site.Lastly,the challenges and opportunities encountered in the field of geotechnical engineering regarding the establishment of lunar lava tube bases are discussed,encompassing cave exploration technologies,in-situ testing methods,geomechanical properties under lunar extreme environments,base design and structural stability assessment,excavation and reinforcement techniques,and simulated Earth-based lava tube base.
基金supported by National Natural Science Foundation of China(No.42172319)the Fundamental Research Funds for the Central Universities(No.2023ZKPYLJ01)。
文摘The development and utilization of lunar resources are entering a critical stage.Immediate focus is needed on key technologies for in-situ resource utilization(ISRU)and lunar base construction.This paper comparatively analyzes the basic characteristics of lunar regolith samples returned from Chang'e-5(CE-5),Apollo,and Luna missions,focusing on their physical,mechanical,mineral,chemical,and morphological parameters.Given the limited availability of lunar regolith,more than 50 lunar regolith simulants are summarized.The differences between lunar regolith and simulants concerning these parameters are discussed.To facilitate the construction of lunar bases,this article summarizes the advancements in research on construction materials derived from lunar regolith simulants.Based on statistical results,lunar regolith simulant-based composites are classified into 5 types by their strengthening and toughening mechanisms,and a comprehensive analysis of molding methods,preparation conditions,and mechanical properties is conducted.Furthermore,the potential lunar base construction forms are reviewed,and the adaptability of lunar regolith simulant-based composites and lunar base construction methods are proposed.The key demands of lunar bases constructed with lunar regolith-based composites are discussed,including energy demand,in-situ buildability,service performance,and structural availability.This progress contributes to providing essential material and methodological support for future lunar construction.
文摘The Fenghua River Bridge is a major structure on the highway between Hengzhang and Guojiachi, which is to be built with a four-span prestress concrete (PC) box girder and symmetrical cantilever castings. In this paper, a finite element method (FEM) model is set up to study the effects of concrete differential aging time on the construction phases of the Fenghua River Bridge by calculating the vertical displacement of the folding segment of the middle span and the longitudinal bending moment of Pier 12#. In the model, the girders are classified into 150 changing sections based on the desgn scheme, and their construction is to be carried in 16 phases respectively to build 12 blocks connected by a side folding segment and a middle folding segment, covered with a second dead load and in completion for 20 years. It is found that the internal forces and deformations of the concrete structures at the aging time of 60 d are quite different from those of 0 d aging time while the behaviors of the structures of 120 d aging time is nearly the same as those of 60 d aging time― the differences are so small that can be neglected, suggesting that the creep develops obviously about one month after the cement is hardened and the development fades later on.
文摘As the extension and supplement of explicit curriculum,the English hidden curriculum in higher vocational colleges plays animportant role in cultivating students' behaviors,stimulate their interest and arouse their enthusiasm,initiative and creativity in learningEnglish.This paper analyzes the problems of English hidden curriculum construction in higher vocational colleges under the back-ground o"fInternet plus",and puts forward some corresponding countermeasures to bring the role of college English hidden curriculuminto full play.
文摘OBE theory focuses on students’learning outcomes and application ability,which is consistent with the requirements of the new curriculum standard.The paper attempts to apply OBE theory to innovate the construction of English classroom teaching mode in senior high schools from aspects of teaching aims,teaching activities,teaching assessments and application activities.Results show that the application of OBE in high schools is beneficial to the development of English teaching and students'learning.
文摘There have been heated discussions onthere-be construction in the field of linguistics,and linguists have made numerous attempts to explore it in syntax,semantics,and pragmatics.However,researchers have not reached any consensus.There is a review of the mainstream of the studies to explore what can be done to promote unanimity.
基金This study was supported by the National Key Tech-nologies R & D Program of China (2006BAD03A09)Agrifund of China’s Ministry of Science and Technology (2006GB24910472)
文摘An assessment index system including environment, socio-culture, economy and technology was established for evaluating environmental construction level of community （objective construction）, and questionnaire was designed according to paper review for evaluating residential satisfaction （subjective satisfaction）. The index system was divided into four layers： system （A）, subsystems （B）, categories （C）, and indicators （D）, and in total of 38 indicators was established. The Xihe community, affiliated to Nanfen district, Benxi City, Liaoning Province, China was selected as a case study. Results indicated that the community sustainability index related to objective environmental construction was 0.4355 and was classified as class Ⅲ （moderate）; the community sustainability index related to the residential satisfaction was 0.4255, belonging to class Ⅲ. In conclusion, the sustainability of Xihe community was moderate and needed to be improved. Residential satisfaction was lower than objective environmental construction. The assessment index system established in this study is able to reflect the comprehensive sustainability of community and can be used to evaluate other similar communities＇ sustainability.
文摘In the circle of linguistics,numerous attempts have been made to explore there-be construction in the fields of syntax,semantics,and pragmatics,but in the by-now researches there is little touching on the derivation of the word there.In consequence,herein the focus and effort are put on the derivation of there.It explores the motivation behind the derivation of there based on the cognitive study on there constructions.It is demonstrated that there-be construction derivates to meet the need of the development of human cognitive capacities of expressing abstract mental space.It is mainly motivated by gestalt law,figure-ground theory.
文摘M.Butterfly,written by David Henry Hwang,is one of the most influential plays in contemporary American dramatic his-tory.Hwang incorporates a stereotypical fantasy into his play,involving conflicts and misunderstandings between the East and theWest,between men and women.Through the analysis of the construction of the Orientalist"Madame Butterfly Fantasy"in M.Butterfly,this paper analyzes sexual prejudice and racial bias embedded in the"Fantasy".
文摘According to the definition of tense,English has no actual future tense.The ways to express future time in English vary with the specific situation.We should avoid frequently using the same way to express the future.It is important to study the different construction of the future time in English and its implications in order to make it clear that the appropriate construction to cope with the specific situation should be noticed.
文摘Empty categories,which lack phonological form and hence are not visible in the phonetic representation of the sentence,have both syntactic and semantic properties.Null subjects PRO and pro are base-generated empty categories.This thesis,based on Chomsky's theory about empty categories and research achievements made by Chinese scholars,attempts to analyze the liandong(Serial Verb) construction from Figure and Ground perspective.
文摘In the era of"Internet Plus",emphasis has been placed on construction of teaching resources by utilizing internet platform andtechnologies.It is of great significance to discuss the construction of English teaching resources in higher vocational colleges from theperspective of ecopedagogy which is characterized by openness and diversity.We can achieve high efficiency and effectiveness in con-structing English teaching resources for higher vocational college students through abiding by following principles such as diversity,de-velopment,adaptation and openness.
文摘English ditransitive construction is a significant component of Goldberg's construction grammar which is based on cognitive linguistics. It aims to enlighten teachers and learners of SLA. It presents backgrounds and the basic concepts of Goldberg's construction grammar, depicts what English ditransitive construction is and its semantic constraints, and refers to enlightments of English ditransitive construction on SLA from four perspectives.
文摘Since the Keyser and Roeper,English middle construction(EMC)has attracted the linguists successfully with its complex syntactic and semantic features.The essential feature of EMC is active in syntactic form and passive in semantic meaning.Semantically,EMC is characterized by non-eventivity,genericity,agentivity and modality.Syntactically,the argument of EMC sentence is the internal argument of the verb,and the verb usually takes the modifier of an adverb or modal verb.Due to the complexity of EMC,many English learners encounter some difficulties in learning the second language.Based on Construction Grammar,this paper mainly investigates the following questions:first,is the learners’acquisition on EMC related to their English proficiency?Second,for typical and untypical EMC,which one is more difficult for them to learn?According to the research objectives,the research finally selects 32 valid papers and divides the subjects into advanced and elementary groups according to their scores in CET-6 and TEM-8,and R Studio is adopted to analyze their acquisition of EMC.The research results show that:first,the learners’acquisition on EMC is related to their English proficiency.Second,for typical and untypical EMC,both of them acquire typical EMC better than the untypical one,so the typical EMC is more difficult for the them to learn.
基金Sponsored by National Natural Science Foundation of China (21231002,21276026,21271023,21173021,91022006,11202193,11172276,and 11072225)the 111 Project ( B07012)+1 种基金the Program of Cooperation of the Beijing Education Commission ( 20091739006)Specialized Research Fund for the Doctoral Program of Higher Education ( 20101101110031)
文摘The recent research progress of structure- and size-controlled micro/nano-energetic materials is reviewed, which properties are fundamentally different from those of their corresponding bulk materials. The development of the construction strategies for achieving zero-dimensional (0D), one-dimensional (1D), two-dimensional (2D), and three-dimensional (3D) micro/nanostructures from energetic molecules is introduced. Also, an overview of the unique properties induced by micro/nanostructures and size effects is provided. Special emphasis is focused on the size-dependent properties that are different from those of the conventional micro-sized energetic materials, such as thermal decomposition, sensitivity, combustion and detonation, and compaction behaviors. A conclusion and our view of the future development of micro/nano-energetic materials and devices are given.
文摘Attribute-based encryption is drawing more attention with its inherent attractive properties which are potential to be widely used in the newly developing cloud computing. However, one of the main obstacles for its application is how to revoke the attributes of the users, though some ABE schemes have realized revocation, they mostly focused on the user revocation that revokes the user＇s whole attributes, or attribute revocation under the indirect revocation model such that all the users＇ private keys will be affected by the revocation. In this paper, we define the model of CP-ABE supporting the attribute revocation under the direct revocation model, in which the revocation list is embed in the ciphertext and none of the users＇ private keys will be affected by the revocation process. Then we propose a generic construction, and prove its security with the decision q-BDHE assumption.
基金Financial support from the National Key Research and Development Program of China(2017YFE0113500)the National Natu 1 ral Science Foundation of China(51872027 and 51772077)are gratefully acknowledged.
文摘MXenes are a family of two-dimensional (2D) transition metal carbides, carbonitrides/nitrides with superior physical and chemical properties, which have attracted extensive attention since the discovery in 2011. The impressive electrochemical activity of MXene makes it one of the most potential electrode materials in rechargeable batteries and supercapacitors. However, single-component MXene electrodes are difficult to achieve high specific capacity, efficient ion/electron transport, and high stability compatibility in an electrochemical environment. Studies have shown that it is an effective method to introduce nanomaterials between MXene layers to construct heterostructures and to improve the electrochemical performance through the synergistic effect among the components in the heterostructures. The introduction of nanomaterials can effectively suppress the restacking of MXene nanosheets, shorten the diffusion path of ions and promote the electrolyte transport, which is beneficial to enhance the rate performance of MXene;moreover, the excellent mechanical flexibility of MXene can reduce the volume expansion of nanomaterials during charge/discharge, thereby effectively protecting the integrity of the electrode structure and improving the cycling stability. Therefore, in this review, combined with theoretical calculations, we summarize the recent advances of MXene heterostructures in terms of synthesis strategies and energy storage applications, including supercapacitors, metal-ions batteries (Li, Na, K, Mg, Zn, Al) and metal anode protection. Furthermore, potential challenges and application perspectives for MXene heterostructures are also outlined.
基金supported in part by National Natural Science Foundation of China(61671324)the Director’s Funding from Qingdao National Laboratory for Marine Science and Technology
文摘In the Davey-MacKay(DM) construction,the inner decoder treats unknown transmitted bits as random independent substitution errors. It limits the synchronization capability of the inner decoder, and thus weakens the error-correcting capability of the DM construction.In order to improve the performance of the DM construction, an iterative decoding scheme is proposed, which iteratively utilizes the more accurate estimates of transmitted codewords. In the proposed scheme, the estimated average bit error rates and the estimated low-density parity-check(LDPC) codewords from the outer decoder are fed back into the inner decoder to update the synchronization process. Simulation results show that the proposed iterative decoding scheme significantly outperforms the traditional DM construction.
基金the National Natural Science Foundation of China，the National Key Basic Research Program of China，The authors would like to thank all project partners for their valuable contributions and feedbacks
文摘Abstract： The layered decoding algorithm has been widely used in the implementation of Low Density Parity Check （LDPC） decoders, due to its high convergence speed. However, the pipeline operation of the layered decoder may introduce memory access conflicts, which heavily deteriorates the decoder throughput. To essentially deal with the issue of memory access conflicts,
基金supported by the National Basic Research Program of China (Project No. 2005CB221405)
文摘A novel particle/metal-based monolithic catalysts dual-bed reactor with beds-interspace supplementary oxygen is constructed comprising of the upper-layer 5 wt%Na2WO4-2 wt%Mn/SiO2 particle catalyst and the under-layer 3 wt%Ce-5 wt%Na2WO4-2 wt%Mn/SBA-15/Al2O3/FeCrA1 metal-based monolithic catalyst as well as a side tube in the interspaces of two layers for supplementing 02. The reaction performance of oxidative coupling of methane （OCM） in the dual-bed reactor system is evaluated. The effects of the reaction parameters such as feed CH4/O2 ratio, reaction temperature and side tube feed 02 flowrate on the catalytic performance are investigated. The results indicate that the suggested mode of dual-bed reactor exhibits an excellent performance for OCM. CH4 conversion of 33.2%, C2H4 selectivity of 46.5% and C2 yield of 22.5% could be obtained, which have been increased by 6.4%, 4.1% and 5.5%, respectively, as compared with 5 wt%Na2WO4-2 wt%Mn/SiO2 particle catalyst in a single-bed reactor and increased by 10.7%, 31.9% and 17.7%, respectively, as compared with 3 wt%Ce-5 wt%Na2WO4-2 wt%Mn/SBA-15/Al2O3/FeCrA1 metal-based monolithic catalyst in a single-bed reactor. The effective promotion of OCM performance in the reactor would supply a valuable reference for the industrialization of OCM process.
