In this article,we study Kahler metrics on a certain line bundle over some compact Kahler manifolds to find complete Kahler metrics with positive holomorphic sectional(or bisectional)curvatures.Thus,we apply a strateg...In this article,we study Kahler metrics on a certain line bundle over some compact Kahler manifolds to find complete Kahler metrics with positive holomorphic sectional(or bisectional)curvatures.Thus,we apply a strategy to a famous Yau conjecture with a co-homogeneity one geometry.展开更多
The hydrogen evolution reaction(HER)via water electrolysis has gained immense research attention.Seawater electrolysis provides great opportunities for sustainable energy production,but is extremely challenging.Transi...The hydrogen evolution reaction(HER)via water electrolysis has gained immense research attention.Seawater electrolysis provides great opportunities for sustainable energy production,but is extremely challenging.Transition metal phosphides are promising candidate electrocatalysts.Herein,we prepared a novel Fe-Co_(2)P bundle of nanorods(BNRs)for catalyzing the HER in seawater electrolysis and over the entire p H range.Cobalt phosphides with different crystal phases and morphologies were obtained by varying the Fe doping amount.The Co:Fe molar ratio of 1:0.5 was found to be optimum.The Fe doping improved the HER performance of Co_(2)P over the entire p H range by providing favorable electronic properties and morphology,lattice distortion,and special coordination environment.The Fe-Co_(2)P BNRs showed higher catalytic activity than 20%Pt/C in seawater at high potentials.The density functional theory calculations revealed that the Fe doping reduced the hydrogen binding strength of Co_(2)P to efficiently accelerate the HER kinetics and produce a favorable charge density.This study provides valuable insights into the design and development of high-efficiency HER catalysts for large-scale seawater electrolysis.展开更多
Ordered hierarchical architectures are attractive candidates for electrochemical energy storage applications.Herein,a facile self-template strategy is applied to prepare Fe7Se8 architectures with a monolithic structur...Ordered hierarchical architectures are attractive candidates for electrochemical energy storage applications.Herein,a facile self-template strategy is applied to prepare Fe7Se8 architectures with a monolithic structure via a self-synthesized single precursor and subsequent calcination at high temperature.With the support of oleylamine,the precursor is structurally targeted to engineer the Fe7Se8 microstructure,featuring nanorod bundles arranged along the longitudinal direction.Because of their ordered hierarchical structure,the Fe7Se8 nanorod bundles deliver a high reversible capacity of 300 m Ah g^-1 at 0.5 A g^-1,along with exceptional rate capability up to 20 A g^-1 and long-term cycle life over 8000 cycles,which represents the highest stability of Fe7Se8 anodes for sodium-ion batteries reported to date.The feasibility of the present strategy to prepare metal selenide structures highlights its promising potential for the rational and effective engineering of electrode materials responsible for the electrochemical performance of energy storage systems.展开更多
An experimental study on heat transfer and resistance coefficients of linearly arranged smooth and spirally corrugated tube bundles in cross-flow was performed. The heat transfer and resistance coefficients are presen...An experimental study on heat transfer and resistance coefficients of linearly arranged smooth and spirally corrugated tube bundles in cross-flow was performed. The heat transfer and resistance coefficients are presented in this paper with transverse and longitudinal tube-pitch and tube geometries taken into account. The experiment's results can provide technical guidelines for application to horizontal air preheater with arranged in-line spirally corrugated tube bundles, especially to the air preheater for CFBCBs (Circulating Fluidized Bed Combustion Boilers).展开更多
Spacer grids play an important role in pressurized water reactor（PWR） fuel assembly in that they have significant influence on the thermal-hydraulic characteristics of the reactor core.But so far,the numerical studi...Spacer grids play an important role in pressurized water reactor（PWR） fuel assembly in that they have significant influence on the thermal-hydraulic characteristics of the reactor core.But so far,the numerical studies are performed without regarding dimple and spring of spacer grids,just considering mixing vane.Moreover,these studies use k-ε turbulence model without considering the suitability of the other turbulence models upon the different spacer grids flow.A study is carried out to understand the 3-D single-phase flow in AFA-2G 5×5 rod bundles with spacer grids based on numerical method.In order to investigate the suitability of different turbulence models,k-ε model and k-ω model,the influence of different parts of spacer grid on the fluid flow is also predicted.By using second-order upwind scheme,hybrid grids technique,and improved SIMPLEC algorithm,the Reynolds averaged mass conservation and momentum conservation equations are solved,and the pressure and velocity field of flow are obtained.The numerical simulation results are compared with experiment results and the agreement is satisfactory.The simulation results show the influences of the spring,dimple and mixing vane,and the different characteristics of the k-ε model and k-ω model.Comparing with the experiment results,the simulation results suggest that the k-ω model is suitable for the simulation of the rod bundle flow with spacer grids;the spring and dimple are the main causes of the pressure loss in the spacer grid channel.The friction coefficient of the channel with spring and dimple is 1.5 times the coefficient of the channel with the vane.These results are beneficial to enhance the simulation ability of spacer grids flow and optimization design ability of spaces grid.展开更多
Tensile impact tests of aramid (Twaron) fiber bundles were carried out under high strain rates with a wide range of 0. 01/s -1 000/s by using MTS and bar-bar tensile impact apparatus. Based on the statistical constitu...Tensile impact tests of aramid (Twaron) fiber bundles were carried out under high strain rates with a wide range of 0. 01/s -1 000/s by using MTS and bar-bar tensile impact apparatus. Based on the statistical constitutive model of fiber bundles, statistical constitutive equations of aramid fiber bundles are derived from statistical analysis of test data at different strain rates. Comparison between the theoretical predictions and experimental data indicates statistical constitutive equations fit well with the experimental data, and statistical constitutive equations of fiber bundles at different strain rates are valid.展开更多
In this paper,we solve the Dirichlet problem for the Hermitian-Einstein equations on Higgs bundles over compact Hermitian manifolds.Then we prove the existence of the Hermitian-Einstein metrics on Higgs bundles over a...In this paper,we solve the Dirichlet problem for the Hermitian-Einstein equations on Higgs bundles over compact Hermitian manifolds.Then we prove the existence of the Hermitian-Einstein metrics on Higgs bundles over a class of complete Hermitian manifolds.展开更多
Carbon nanotube bundles are promising thermal interfacial materials due to their excellent thermal and mechanical characteristics. In this study, the phonon dispersion relations and density of states of the single-wal...Carbon nanotube bundles are promising thermal interfacial materials due to their excellent thermal and mechanical characteristics. In this study, the phonon dispersion relations and density of states of the single-wall carbon nanotube bundles are calculated by using the force constant model. The calculation results show that the inter-tube interaction leads to a significant frequency raise of the low frequency modes. To verify the applied calculation method, the specific heat of a single single-wall carbon nanotube is calculated first based on the obtained phonon dispersion relations and the results coincide well with the experimental data. Moreover, the specific heat of the bundles is calculated and exhibits a slight reduction at low temperatures in comparison with that of the single tube. The thermal conductivity of the bundles at low temperatures is calculated by using the ballistic transport model. The calculation results indicate that the inter-tube interaction, i.e. van der Waals interaction, hinders heat transfer and cannot be neglected at extremely low temperatures. For （5, 5） bundles, the relative difference of the thermal conductivity caused by ignoring inter-tube effect reaches the maximum value of 26% around 17 K, which indicates the significant inter-tube interaction effect on the thermal conductivity at low temperatures.展开更多
This paper deals with the analytical derivation of phasor-domain statistical properties of crosstalk in random wire cables due to the superposition of several sources of electromagnetic interference.In this study,stat...This paper deals with the analytical derivation of phasor-domain statistical properties of crosstalk in random wire cables due to the superposition of several sources of electromagnetic interference.In this study,statistical characterization of crosstalk in cable bundles,which is available in literature for the case of one source of interference,is extended to the case of several sources operating simultaneously.The superposition of crosstalk effects is analysed in statistical terms,also taking into account the correlation between crosstalk contributions.A further random contribution,which is included in the proposed statistical model,is given by the phase relationship between the sources of interference.Analytical approximate expressions for the crosstalk mean value,variance,and probability density function are derived as functions of the cable bundle features and sources.展开更多
Purpose:A new point of view in the study of impact is introduced.Design/methodology/approach:Using fundamental theorems in real analysis we study the convergence of well-known impact measures.Findings:We show that poi...Purpose:A new point of view in the study of impact is introduced.Design/methodology/approach:Using fundamental theorems in real analysis we study the convergence of well-known impact measures.Findings:We show that pointwise convergence is maintained by all well-known impact bundles(such as the h-,g-,and R-bundle)and that theμ-bundle even maintains uniform convergence.Based on these results,a classification of impact bundles is given.Research limitations:As for all impact studies,it is just impossible to study all measures in depth.Practical implications:It is proposed to include convergence properties in the study of impact measures.Originality/value:This article is the first to present a bundle classification based on convergence properties of impact bundles.展开更多
Only a few species of aphids induce galls. Among these, Paracletus cimiciformis, Forda marginata, Forda formicaria, Geoica utricularia and Baizongia pistaciae induce galls on Pistacia terebinthus leaflets. Prior to pr...Only a few species of aphids induce galls. Among these, Paracletus cimiciformis, Forda marginata, Forda formicaria, Geoica utricularia and Baizongia pistaciae induce galls on Pistacia terebinthus leaflets. Prior to present study the author examined microscopically P. terebinthus leaflets. He also studied the microscopic morphology of galls induced by the five species mentioned above. A clear microscopic difference between these galls is that in the wall of galls induced by the genera Paracletus and Forda a single vascular bundle is seen. The interpretation is that these galls are laminae of the modified leaflets. However, in the walls of the galls induced by the genera Geoica and Baizongia, two vascular bundles are observed. In the present paper a study of the early stages of development of galls produced by G. utricularia is described. The study was designed to explain the origin of the two vascular bundles present in the walls of these galls. The findings indicate that the aphid induces a massive development of the two vascular bundles present in the midvein of the leaflets of P. terebinthus: the main vascular bundle and the small supernumerary vascular bundle. Both these extremely developed vascular bundles occupy the walls of the galls induced by G. utricularia.展开更多
Stressful stimuli induced by immobilization are perceived as acute stress in rats. This acute stress activates corticotropin-releasing hormone (CRH) neurons in the hypothalamic paraventricular nucleus (PVN), resulting...Stressful stimuli induced by immobilization are perceived as acute stress in rats. This acute stress activates corticotropin-releasing hormone (CRH) neurons in the hypothalamic paraventricular nucleus (PVN), resulting in stimulation of the hypothalamic-pituitary-adrenal (HPA) axis. The ventral ascending noradrenergic bundles (V-NAB) from the brainstem innervate the PVN. To investigate the relationship between the response of the HPA axis and the V-NAB, we examined changes in plasma corticosterone, the final output of the HPA axis, and extracellular noradrenaline (NA) in the PVN following immobilization stress in rats that received bilateral 6-hydroxydopamine (6-OHDA) lesions of the V-NAB. 6-OHDA microinjection into the V-NAB reduced the magnitude of the responses of plasma corticosterone and extracellular NA in the PVN following immobilization stress. Our results suggest that V-NAB innervation of the PVN is involved in immobilization stress-induced activation of the HPA axis.展开更多
As the most frequent word sequence in register,lexical bundles are the basic components of discourse.Their use is of great help to the fluency and accuracy of academic writing.In the past two decades,the study of lexi...As the most frequent word sequence in register,lexical bundles are the basic components of discourse.Their use is of great help to the fluency and accuracy of academic writing.In the past two decades,the study of lexical bundles has focused on the body part of academic papers,but less on the abstract.In order to identify and compare the differences in the use of lexical bundles in English abstracts between international and Chinese authors,this paper selects English abstracts from Chinese and International high-level academic journals in the discipline of linguistics from 2018 to 2020 to build two corpora of English abstracts of academic writings:Corpus of English Abstracts from International Linguistics Journal Articles(ILJA)and Corpus of English Abstracts from Chinese Linguistics Journal Articles(CLJA).This paper analyzes the differences of English abstract writing between Chinese and international high-level linguistics journals,and provides enlightenment for abstract writing and teaching.展开更多
In recent years, there have been emergent interests in L2 learners＇ implicit lexical knowledge. Researchers employed psycholinguistic methods to investigate the online processing of formulaic sequences in L2 （idioms...In recent years, there have been emergent interests in L2 learners＇ implicit lexical knowledge. Researchers employed psycholinguistic methods to investigate the online processing of formulaic sequences in L2 （idioms and collocations） and find evidence for holistic processing of the target linguistic sequences. This paper reviews and comments on lexical bundles and related concepts, trying to make clear this well focused research area in second language acquisition （SLA）. Literature is reviewed and criticized on frequency effect in L2 learning, formulaic sequences, and implicit/explicit knowledge/learning, including their theoretical basis, methodology, and conclusion. In this paper, the author argues that sufficient practice, either receptive or productive, can turn explicit knowledge implicit, making it automatically accessed and retrieved. Suggestions on further study in lexical bundles are given.展开更多
In this paper, an efficient multi-conductor simplification technique is proposed to model the electromagnetic immunity on cable bundles within a braid shielding structure over a large frequency range. By grouping toge...In this paper, an efficient multi-conductor simplification technique is proposed to model the electromagnetic immunity on cable bundles within a braid shielding structure over a large frequency range. By grouping together the conductors based on the knowledge of Z-Smith chart, the required computation time is markedly reduced and the complexity of modeling the completely shielding cable bundles is significantly simplified with a good accuracy. After a brief description of the immunity problems in shielding structure, a six-phase procedure is detailed to generate the geometrical characteristics of the reduced cable bundles. Numerical simulation is carried out by using a commercial software CST to validate the efficiency and advantages of the proposed approach. The research addressed in this paper is considered as a simplified modeling technique for the electromagnetic immunity within a shielding structure.展开更多
In the project of MeAWaT*, an innovative hollow pin is designed. For reactor design calculations, it is necessaryto predict the hydraulic losses in multi-rod fuel bundles accurately[1]. And there is a long history for...In the project of MeAWaT*, an innovative hollow pin is designed. For reactor design calculations, it is necessaryto predict the hydraulic losses in multi-rod fuel bundles accurately[1]. And there is a long history for the use of spiralwire to maintain the pins in their position in fuel assemblies of reactors[2]. In this paper, a series of computationalfluid dynamics (CFD) calculations are carried out on wire-wrapped pins, with constant pin length and differentwire pitches. A new correlation is proposed.展开更多
Different from other types of word combinations,lexical bundles are frequency-driven word combinations,which are characterized by incomplete structure,yet different functional discourse performance.Lexical bundles are...Different from other types of word combinations,lexical bundles are frequency-driven word combinations,which are characterized by incomplete structure,yet different functional discourse performance.Lexical bundles are the important building blocks of discourse.Appropriate use of lexical bundles contribute to fluent and accurate written and spoken production.This paper collates,analyzes and summaries the literature reviews on lexical bundles both at home and abroad,to point out the present situation and weakness of the research on lexical bundles.展开更多
文摘In this article,we study Kahler metrics on a certain line bundle over some compact Kahler manifolds to find complete Kahler metrics with positive holomorphic sectional(or bisectional)curvatures.Thus,we apply a strategy to a famous Yau conjecture with a co-homogeneity one geometry.
基金the support by the Fundamental Research Funds for the Central Universities(No.19CX02008A)the China Postdoctoral Science Foundation(No.2018M642726)+1 种基金the Petro China Innovation Foundation(No.2019D-5007-0401)the Taishan Scholars Program of Shandong Province。
文摘The hydrogen evolution reaction(HER)via water electrolysis has gained immense research attention.Seawater electrolysis provides great opportunities for sustainable energy production,but is extremely challenging.Transition metal phosphides are promising candidate electrocatalysts.Herein,we prepared a novel Fe-Co_(2)P bundle of nanorods(BNRs)for catalyzing the HER in seawater electrolysis and over the entire p H range.Cobalt phosphides with different crystal phases and morphologies were obtained by varying the Fe doping amount.The Co:Fe molar ratio of 1:0.5 was found to be optimum.The Fe doping improved the HER performance of Co_(2)P over the entire p H range by providing favorable electronic properties and morphology,lattice distortion,and special coordination environment.The Fe-Co_(2)P BNRs showed higher catalytic activity than 20%Pt/C in seawater at high potentials.The density functional theory calculations revealed that the Fe doping reduced the hydrogen binding strength of Co_(2)P to efficiently accelerate the HER kinetics and produce a favorable charge density.This study provides valuable insights into the design and development of high-efficiency HER catalysts for large-scale seawater electrolysis.
基金the National Natural Science Foundation of China(21871164)the Natural Science Foundation of Shandong Province(ZR2019MB024)the Taishan Scholar Project of Shandong Province(no.ts201511004).
文摘Ordered hierarchical architectures are attractive candidates for electrochemical energy storage applications.Herein,a facile self-template strategy is applied to prepare Fe7Se8 architectures with a monolithic structure via a self-synthesized single precursor and subsequent calcination at high temperature.With the support of oleylamine,the precursor is structurally targeted to engineer the Fe7Se8 microstructure,featuring nanorod bundles arranged along the longitudinal direction.Because of their ordered hierarchical structure,the Fe7Se8 nanorod bundles deliver a high reversible capacity of 300 m Ah g^-1 at 0.5 A g^-1,along with exceptional rate capability up to 20 A g^-1 and long-term cycle life over 8000 cycles,which represents the highest stability of Fe7Se8 anodes for sodium-ion batteries reported to date.The feasibility of the present strategy to prepare metal selenide structures highlights its promising potential for the rational and effective engineering of electrode materials responsible for the electrochemical performance of energy storage systems.
文摘An experimental study on heat transfer and resistance coefficients of linearly arranged smooth and spirally corrugated tube bundles in cross-flow was performed. The heat transfer and resistance coefficients are presented in this paper with transverse and longitudinal tube-pitch and tube geometries taken into account. The experiment's results can provide technical guidelines for application to horizontal air preheater with arranged in-line spirally corrugated tube bundles, especially to the air preheater for CFBCBs (Circulating Fluidized Bed Combustion Boilers).
基金supported by National Key Laboratory of Bubble Physics and Natural Circulation of China(Grant No. 51482040105CB0103)
文摘Spacer grids play an important role in pressurized water reactor（PWR） fuel assembly in that they have significant influence on the thermal-hydraulic characteristics of the reactor core.But so far,the numerical studies are performed without regarding dimple and spring of spacer grids,just considering mixing vane.Moreover,these studies use k-ε turbulence model without considering the suitability of the other turbulence models upon the different spacer grids flow.A study is carried out to understand the 3-D single-phase flow in AFA-2G 5×5 rod bundles with spacer grids based on numerical method.In order to investigate the suitability of different turbulence models,k-ε model and k-ω model,the influence of different parts of spacer grid on the fluid flow is also predicted.By using second-order upwind scheme,hybrid grids technique,and improved SIMPLEC algorithm,the Reynolds averaged mass conservation and momentum conservation equations are solved,and the pressure and velocity field of flow are obtained.The numerical simulation results are compared with experiment results and the agreement is satisfactory.The simulation results show the influences of the spring,dimple and mixing vane,and the different characteristics of the k-ε model and k-ω model.Comparing with the experiment results,the simulation results suggest that the k-ω model is suitable for the simulation of the rod bundle flow with spacer grids;the spring and dimple are the main causes of the pressure loss in the spacer grid channel.The friction coefficient of the channel with spring and dimple is 1.5 times the coefficient of the channel with the vane.These results are beneficial to enhance the simulation ability of spacer grids flow and optimization design ability of spaces grid.
基金The project is supported by Zhejiang Provincial Natural Science Foundaion of China(599113)Science and Technology Foundation of Ministy of Educationd of China(DF 02064)
文摘Tensile impact tests of aramid (Twaron) fiber bundles were carried out under high strain rates with a wide range of 0. 01/s -1 000/s by using MTS and bar-bar tensile impact apparatus. Based on the statistical constitutive model of fiber bundles, statistical constitutive equations of aramid fiber bundles are derived from statistical analysis of test data at different strain rates. Comparison between the theoretical predictions and experimental data indicates statistical constitutive equations fit well with the experimental data, and statistical constitutive equations of fiber bundles at different strain rates are valid.
基金supported in part by NSFC(11625106,11571332,11721101)the second author was supported by the Fundamental Research Funds for the Central Universities(19lgpy239)。
文摘In this paper,we solve the Dirichlet problem for the Hermitian-Einstein equations on Higgs bundles over compact Hermitian manifolds.Then we prove the existence of the Hermitian-Einstein metrics on Higgs bundles over a class of complete Hermitian manifolds.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 50730006 and 50976053)
文摘Carbon nanotube bundles are promising thermal interfacial materials due to their excellent thermal and mechanical characteristics. In this study, the phonon dispersion relations and density of states of the single-wall carbon nanotube bundles are calculated by using the force constant model. The calculation results show that the inter-tube interaction leads to a significant frequency raise of the low frequency modes. To verify the applied calculation method, the specific heat of a single single-wall carbon nanotube is calculated first based on the obtained phonon dispersion relations and the results coincide well with the experimental data. Moreover, the specific heat of the bundles is calculated and exhibits a slight reduction at low temperatures in comparison with that of the single tube. The thermal conductivity of the bundles at low temperatures is calculated by using the ballistic transport model. The calculation results indicate that the inter-tube interaction, i.e. van der Waals interaction, hinders heat transfer and cannot be neglected at extremely low temperatures. For （5, 5） bundles, the relative difference of the thermal conductivity caused by ignoring inter-tube effect reaches the maximum value of 26% around 17 K, which indicates the significant inter-tube interaction effect on the thermal conductivity at low temperatures.
文摘This paper deals with the analytical derivation of phasor-domain statistical properties of crosstalk in random wire cables due to the superposition of several sources of electromagnetic interference.In this study,statistical characterization of crosstalk in cable bundles,which is available in literature for the case of one source of interference,is extended to the case of several sources operating simultaneously.The superposition of crosstalk effects is analysed in statistical terms,also taking into account the correlation between crosstalk contributions.A further random contribution,which is included in the proposed statistical model,is given by the phase relationship between the sources of interference.Analytical approximate expressions for the crosstalk mean value,variance,and probability density function are derived as functions of the cable bundle features and sources.
基金The author thanks Li Li(National Science Library,CAS)for drawing Figure 1.
文摘Purpose:A new point of view in the study of impact is introduced.Design/methodology/approach:Using fundamental theorems in real analysis we study the convergence of well-known impact measures.Findings:We show that pointwise convergence is maintained by all well-known impact bundles(such as the h-,g-,and R-bundle)and that theμ-bundle even maintains uniform convergence.Based on these results,a classification of impact bundles is given.Research limitations:As for all impact studies,it is just impossible to study all measures in depth.Practical implications:It is proposed to include convergence properties in the study of impact measures.Originality/value:This article is the first to present a bundle classification based on convergence properties of impact bundles.
文摘Only a few species of aphids induce galls. Among these, Paracletus cimiciformis, Forda marginata, Forda formicaria, Geoica utricularia and Baizongia pistaciae induce galls on Pistacia terebinthus leaflets. Prior to present study the author examined microscopically P. terebinthus leaflets. He also studied the microscopic morphology of galls induced by the five species mentioned above. A clear microscopic difference between these galls is that in the wall of galls induced by the genera Paracletus and Forda a single vascular bundle is seen. The interpretation is that these galls are laminae of the modified leaflets. However, in the walls of the galls induced by the genera Geoica and Baizongia, two vascular bundles are observed. In the present paper a study of the early stages of development of galls produced by G. utricularia is described. The study was designed to explain the origin of the two vascular bundles present in the walls of these galls. The findings indicate that the aphid induces a massive development of the two vascular bundles present in the midvein of the leaflets of P. terebinthus: the main vascular bundle and the small supernumerary vascular bundle. Both these extremely developed vascular bundles occupy the walls of the galls induced by G. utricularia.
文摘Stressful stimuli induced by immobilization are perceived as acute stress in rats. This acute stress activates corticotropin-releasing hormone (CRH) neurons in the hypothalamic paraventricular nucleus (PVN), resulting in stimulation of the hypothalamic-pituitary-adrenal (HPA) axis. The ventral ascending noradrenergic bundles (V-NAB) from the brainstem innervate the PVN. To investigate the relationship between the response of the HPA axis and the V-NAB, we examined changes in plasma corticosterone, the final output of the HPA axis, and extracellular noradrenaline (NA) in the PVN following immobilization stress in rats that received bilateral 6-hydroxydopamine (6-OHDA) lesions of the V-NAB. 6-OHDA microinjection into the V-NAB reduced the magnitude of the responses of plasma corticosterone and extracellular NA in the PVN following immobilization stress. Our results suggest that V-NAB innervation of the PVN is involved in immobilization stress-induced activation of the HPA axis.
文摘As the most frequent word sequence in register,lexical bundles are the basic components of discourse.Their use is of great help to the fluency and accuracy of academic writing.In the past two decades,the study of lexical bundles has focused on the body part of academic papers,but less on the abstract.In order to identify and compare the differences in the use of lexical bundles in English abstracts between international and Chinese authors,this paper selects English abstracts from Chinese and International high-level academic journals in the discipline of linguistics from 2018 to 2020 to build two corpora of English abstracts of academic writings:Corpus of English Abstracts from International Linguistics Journal Articles(ILJA)and Corpus of English Abstracts from Chinese Linguistics Journal Articles(CLJA).This paper analyzes the differences of English abstract writing between Chinese and international high-level linguistics journals,and provides enlightenment for abstract writing and teaching.
文摘In recent years, there have been emergent interests in L2 learners＇ implicit lexical knowledge. Researchers employed psycholinguistic methods to investigate the online processing of formulaic sequences in L2 （idioms and collocations） and find evidence for holistic processing of the target linguistic sequences. This paper reviews and comments on lexical bundles and related concepts, trying to make clear this well focused research area in second language acquisition （SLA）. Literature is reviewed and criticized on frequency effect in L2 learning, formulaic sequences, and implicit/explicit knowledge/learning, including their theoretical basis, methodology, and conclusion. In this paper, the author argues that sufficient practice, either receptive or productive, can turn explicit knowledge implicit, making it automatically accessed and retrieved. Suggestions on further study in lexical bundles are given.
基金Project supported by the National Natural Science Foundation of China(Grant No.51675086)the National Defense Pre-Research Foundation of China(Grant No.6140758010116DZ02002)
文摘In this paper, an efficient multi-conductor simplification technique is proposed to model the electromagnetic immunity on cable bundles within a braid shielding structure over a large frequency range. By grouping together the conductors based on the knowledge of Z-Smith chart, the required computation time is markedly reduced and the complexity of modeling the completely shielding cable bundles is significantly simplified with a good accuracy. After a brief description of the immunity problems in shielding structure, a six-phase procedure is detailed to generate the geometrical characteristics of the reduced cable bundles. Numerical simulation is carried out by using a commercial software CST to validate the efficiency and advantages of the proposed approach. The research addressed in this paper is considered as a simplified modeling technique for the electromagnetic immunity within a shielding structure.
文摘In the project of MeAWaT*, an innovative hollow pin is designed. For reactor design calculations, it is necessaryto predict the hydraulic losses in multi-rod fuel bundles accurately[1]. And there is a long history for the use of spiralwire to maintain the pins in their position in fuel assemblies of reactors[2]. In this paper, a series of computationalfluid dynamics (CFD) calculations are carried out on wire-wrapped pins, with constant pin length and differentwire pitches. A new correlation is proposed.
文摘Different from other types of word combinations,lexical bundles are frequency-driven word combinations,which are characterized by incomplete structure,yet different functional discourse performance.Lexical bundles are the important building blocks of discourse.Appropriate use of lexical bundles contribute to fluent and accurate written and spoken production.This paper collates,analyzes and summaries the literature reviews on lexical bundles both at home and abroad,to point out the present situation and weakness of the research on lexical bundles.
