A stable polyradical, poly (2,2,6,6-tetramethylpiperidinyloxy methacrylate) (PTMA), was synthesized,and its structure was determined by infrared, ultraviolet-visible, and ESR spectroscopy. Cyclic voltammograms ofthe P...A stable polyradical, poly (2,2,6,6-tetramethylpiperidinyloxy methacrylate) (PTMA), was synthesized,and its structure was determined by infrared, ultraviolet-visible, and ESR spectroscopy. Cyclic voltammograms ofthe PTMA polyradical electrodes were obtained by using a three-electrode cell at a scan rate of 5 mV/s within a po-tential range of 3.2-4. 0 V. The results show that the shape of oxidation peak is very similar to that of reductionpeak, and oxidation peak current is equal to the corresponding reduction peak current, which suggest that PTMApossesses an excellent reversibility. The difference of the anodic peak potential (Ea,p =3.66 V, vs Li/Li+ ) and ca-thodic peak potential(Ec,p =3.58 V, vs Li/Li+ ) is estimated at 80 mV, which is extremely less than that of the oth-er organic positive materials in lithium second batteries such as organosulfide compounds, leading to a capability forhigh current capability in the charging and discharging process of the battery. The maximum discharge specific ca-pacity of PTMA is 78.4 mA @ h/g at the constant discharge current of 0.3 mA (0.2 C rate), the coulombic efficien-cy is about 95%, and the charging and discharging curves of the batteries have an obvious plateau at 3.65 V and3.56 V, respectively. The discharging specific capacity of the battery decreased is about 2% after 100 cycles. ThePTMA/Li button batteries exhibite an excellent stability.展开更多
Second language acquisition can not be understood without addressing the interaction between language and cognition. Cognitive theory can extend to describe learning strategies as complex cognitive skills. Theoretical...Second language acquisition can not be understood without addressing the interaction between language and cognition. Cognitive theory can extend to describe learning strategies as complex cognitive skills. Theoretical developments in Anderson’s production systems cover a broader range of behavior than other theories, including comprehension and production of oral and written texts as well as comprehension, problem solving, and verbal learning.Thus Anderson’s cognitive theory can be served as a rationale for learning strategy studies in second language acquisition.展开更多
In this study,the stagnation point transport of second grade fluid with linear stretching under the effects of variable thermal conductivity is considered.Induced magnetic field impact is also incorporated.The nonline...In this study,the stagnation point transport of second grade fluid with linear stretching under the effects of variable thermal conductivity is considered.Induced magnetic field impact is also incorporated.The nonlinear set of particle differential equations is converted into set of ordinary differential equations through appropriate transformation.The resulting equations are then resolved by optimal homotopy analysis method.The effect of pertinent parameters of interest on skin friction coefficient,temperature,induced magnetic field,velocity and local Nusselt number is inspected by generating appropriate plots.For numerical results,the built-in bvp4 c technique in computational software MATLAB is used for the convergence and residual errors of obtained series solution.It is perceived that the induced magnetic field is intensified by increasing β.It can also be observed that skin friction coefficient enhances with increasing value of magnetic parameter depending on the stretching ratio a/c.For the validness of the obtained results,a comparison has been made and an excellent agreement of current study with existing literature is found.展开更多
With the arrival of the ＂housing stock＂ in first - tier cities, the second - handhousing^market will become the dominant property market. This ardcle aim to the first - tiercities of second - hand housing prices and...With the arrival of the ＂housing stock＂ in first - tier cities, the second - handhousing^market will become the dominant property market. This ardcle aim to the first - tiercities of second - hand housing prices and new home price index for the empirical analysis, thedata related to the cointegration analysis found that the result of the first -tier cities real estatemarket in China, the new home price index is the significant factors influencing the second -hand house price indexi For Beijing, Shanghai second - hand housing and new home price in-dex time series johans test, found that there exists cointegration relationship between two varia-bles,the new city real estate market prices out of a line on the secondary market have clearguide. Therefore, the real estate market regulation aiming at the first -tier cities and the＂housing stock＂ should take the second - hand housing market as the main direction, startingwith the sale price and influencing factors of new houses. At the same time, in different cities,we should adhere to the city＇ s policies, reflect the policy differentiation, promote the reformof the real estate supply side, and promote the return of housing properties.展开更多
Three-year investigation was conducted to demonstrate the mechanism of reduction of soybean yield aroused by continuous and every second year cropping. Compared to normal cropping, there are many unfavorable changes i...Three-year investigation was conducted to demonstrate the mechanism of reduction of soybean yield aroused by continuous and every second year cropping. Compared to normal cropping, there are many unfavorable changes in some major elements of soybean plant and soil environment. Chloropyll content was lower. Phosphorous content of soybean plant was decreased seriously. Potassium content was lower while calcium content was higher. Magnesium content was wot affected and decreased in susceptive varieties. Some deseases and insects of soybean under continuous and wery second year cropping conditions became serious as continuous years prolonged. Organic matter content tended to go down from normal rotation to continuous cropping. Amount of bacteria and antinomyces decreased while amount of fungi increased. The development of symbiotic nitrogen fixation system wsa deteriorated.展开更多
Over the past decade the social structure of China has undergone profound changes. The vertical social mobility between social classes tended to slow down and the social structures and stratification became solidified...Over the past decade the social structure of China has undergone profound changes. The vertical social mobility between social classes tended to slow down and the social structures and stratification became solidified. Phrases such as "second generation of the rich,""second generation of officials,"and "second generation of the farmers"appeared frequently on the Internet and other media,which to some extent reflect the trend in social structure. However,little research has been conducted to address these issues in recent years.This field is in great need of systematic and authoritative surveys and studies on social fragmentation,marginalization,stratification,and mobility.展开更多
A method to estimate the probabilistic density function （PDF） of shear strength parameters was proposed. The second Chebyshev orthogonal polynomial（SCOP） combined with sample moments （the origin moments） was use...A method to estimate the probabilistic density function （PDF） of shear strength parameters was proposed. The second Chebyshev orthogonal polynomial（SCOP） combined with sample moments （the origin moments） was used to approximate the PDF of parameters. X^2 test was adopted to verify the availability of the method. It is distribution-free because no classical theoretical distributions were assumed in advance and the inference result provides a universal form of probability density curves. Six most commonly-used theoretical distributions named normal, lognormal, extreme value Ⅰ , gama, beta and Weibull distributions were used to verify SCOP method. An example from the observed data of cohesion c of a kind of silt clay was presented for illustrative purpose. The results show that the acceptance levels in SCOP are all smaller than those in the classical finite comparative method and the SCOP function is more accurate and effective in the reliability analysis of geotechnical engineering.展开更多
Higher-order band topology not only enriches our understanding of topological phases but also unveils pioneering lower-dimensional boundary states,which harbors substantial potential for next-generation device applica...Higher-order band topology not only enriches our understanding of topological phases but also unveils pioneering lower-dimensional boundary states,which harbors substantial potential for next-generation device applications.The distinct electronic configurations and tunable attributes of two-dimensional materials position them as a quintessential platform for the realization of second-order topological insulators(SOTIs).This article provides an overview of the research progress in SOTIs within the field of two-dimensional electronic materials,focusing on the characterization of higher-order topological properties and the numerous candidate materials proposed in theoretical studies.These endeavors not only enhance our understanding of higher-order topological states but also highlight potential material systems that could be experimentally realized.展开更多
Based on the theoretical origin of sociocultural views,this paper reviews second language writing from the sociocultural perspective in recent years and puts forw ard suggestions for the follow-up study. Research from...Based on the theoretical origin of sociocultural views,this paper reviews second language writing from the sociocultural perspective in recent years and puts forw ard suggestions for the follow-up study. Research from the sociocultural perspective adopts the overall qualitative research methods,with the sociocultural theories and dialogue theories being the framework,attaching importance to the writing process and social context,and concludes that the theoretical basis,research emphasis and methodology still needs perfection.展开更多
The role that information technology plays in foreign language teaching is no longer confined to assisting teachers to impart knowledge. This paper aims at construction of new English teaching model based on informati...The role that information technology plays in foreign language teaching is no longer confined to assisting teachers to impart knowledge. This paper aims at construction of new English teaching model based on information technology. The author adopted ethnographic research to observe 8 classes and the findings of this study suggest that until frontline teachers deepen their understanding of information technology and change their philosophy of teaching can a successful implementation of the new teaching model be ensured.展开更多
The Snows of Kilimanjaro,written by Ernest Hemingway,embodies his writing style typically.The paper focuses on elaborating it from narrative person so that we can grasp and master the theme—beginning is the end,the e...The Snows of Kilimanjaro,written by Ernest Hemingway,embodies his writing style typically.The paper focuses on elaborating it from narrative person so that we can grasp and master the theme—beginning is the end,the end is the beginning.展开更多
More focuses of foreign language teaching theory and practice are on the study of first language and second language acquisition. The article deals with the concept of first and second language acquisition, the relati...More focuses of foreign language teaching theory and practice are on the study of first language and second language acquisition. The article deals with the concept of first and second language acquisition, the relationship between them and the factors influencing on them. The characteristics of the children acquisition and adult acquisition are also studied.展开更多
A finite domain time difference （FDTD） and second-derivative combined method is proposed for the evaluation of phase center in the Fresnel region of complex structure millimeter antennas. This method adopts FDTD＇s ...A finite domain time difference （FDTD） and second-derivative combined method is proposed for the evaluation of phase center in the Fresnel region of complex structure millimeter antennas. This method adopts FDTD＇s near to far field transformation to obtain the fields in Fresnel region and then applies the second-derivative method to calculate the phase center. The adoption of FDTD efficiently overcomes the difficulties arising from the existing calculation methods＇ requirements for the radiation analytical formula of some complex antennas, which makes the existing second-derivative method more applicable in engineering. Also, FDTD increases the precision owing to the superposition field calculation from its extrapolation. The correctness of this proposed method is certified with typical examples and the phase center in the Fresnel region of a microwave radiometry calibration corrugate horn antenna is evaluated with the key features.展开更多
Adaptive broadband beamforraing is a key issue in array applications. The adaptive broadband beamformer with tapped delay line （TDL） structure for nonuniform linear array （NLA） is designed according to the rule of...Adaptive broadband beamforraing is a key issue in array applications. The adaptive broadband beamformer with tapped delay line （TDL） structure for nonuniform linear array （NLA） is designed according to the rule of minimizing the beamformer＇s output power while keeping the distortionless response （DR） in the direction of desired signal and keeping the constant beamwidth （CB） with the prescribed sidelobe level over the whole operating band. This kind of beamforming problem can be solved with the interior-point method after being converted to the form of standard second order cone programming （SOCP）. The computer simulations are presented which illustrate the effectiveness of our beamformer.展开更多
To preserve the sharp features and details of the synthetic aperture radar （SAR） image effectively when despeckling, a despeckling algorithm with edge detection in nonsubsampled second generation bandelet transform ...To preserve the sharp features and details of the synthetic aperture radar （SAR） image effectively when despeckling, a despeckling algorithm with edge detection in nonsubsampled second generation bandelet transform （NSBT） domain is proposed. First, the Canny operator is utilized to detect and remove edges from the SAR image. Then the NSBT which has an optimal approximation to the edges of images and a hard thresholding rule are used to approximate the details while despeckling the edge-removed image. Finally, the removed edges are added to the reconstructed image. As the edges axe detected and protected, and the NSBT is used, the proposed algorithm reaches the state-of-the-art effect which realizes both despeckling and preserving edges and details simultaneously. Experimental results show that both the subjective visual effect and the mainly objective performance indexes of the proposed algorithm outperform that of both Bayesian wavelet shrinkage with edge detection and Bayesian least square-Gaussian scale mixture （BLS-GSM）.展开更多
文摘A stable polyradical, poly (2,2,6,6-tetramethylpiperidinyloxy methacrylate) (PTMA), was synthesized,and its structure was determined by infrared, ultraviolet-visible, and ESR spectroscopy. Cyclic voltammograms ofthe PTMA polyradical electrodes were obtained by using a three-electrode cell at a scan rate of 5 mV/s within a po-tential range of 3.2-4. 0 V. The results show that the shape of oxidation peak is very similar to that of reductionpeak, and oxidation peak current is equal to the corresponding reduction peak current, which suggest that PTMApossesses an excellent reversibility. The difference of the anodic peak potential (Ea,p =3.66 V, vs Li/Li+ ) and ca-thodic peak potential(Ec,p =3.58 V, vs Li/Li+ ) is estimated at 80 mV, which is extremely less than that of the oth-er organic positive materials in lithium second batteries such as organosulfide compounds, leading to a capability forhigh current capability in the charging and discharging process of the battery. The maximum discharge specific ca-pacity of PTMA is 78.4 mA @ h/g at the constant discharge current of 0.3 mA (0.2 C rate), the coulombic efficien-cy is about 95%, and the charging and discharging curves of the batteries have an obvious plateau at 3.65 V and3.56 V, respectively. The discharging specific capacity of the battery decreased is about 2% after 100 cycles. ThePTMA/Li button batteries exhibite an excellent stability.
文摘Second language acquisition can not be understood without addressing the interaction between language and cognition. Cognitive theory can extend to describe learning strategies as complex cognitive skills. Theoretical developments in Anderson’s production systems cover a broader range of behavior than other theories, including comprehension and production of oral and written texts as well as comprehension, problem solving, and verbal learning.Thus Anderson’s cognitive theory can be served as a rationale for learning strategy studies in second language acquisition.
文摘In this study,the stagnation point transport of second grade fluid with linear stretching under the effects of variable thermal conductivity is considered.Induced magnetic field impact is also incorporated.The nonlinear set of particle differential equations is converted into set of ordinary differential equations through appropriate transformation.The resulting equations are then resolved by optimal homotopy analysis method.The effect of pertinent parameters of interest on skin friction coefficient,temperature,induced magnetic field,velocity and local Nusselt number is inspected by generating appropriate plots.For numerical results,the built-in bvp4 c technique in computational software MATLAB is used for the convergence and residual errors of obtained series solution.It is perceived that the induced magnetic field is intensified by increasing β.It can also be observed that skin friction coefficient enhances with increasing value of magnetic parameter depending on the stretching ratio a/c.For the validness of the obtained results,a comparison has been made and an excellent agreement of current study with existing literature is found.
文摘With the arrival of the ＂housing stock＂ in first - tier cities, the second - handhousing^market will become the dominant property market. This ardcle aim to the first - tiercities of second - hand housing prices and new home price index for the empirical analysis, thedata related to the cointegration analysis found that the result of the first -tier cities real estatemarket in China, the new home price index is the significant factors influencing the second -hand house price indexi For Beijing, Shanghai second - hand housing and new home price in-dex time series johans test, found that there exists cointegration relationship between two varia-bles,the new city real estate market prices out of a line on the secondary market have clearguide. Therefore, the real estate market regulation aiming at the first -tier cities and the＂housing stock＂ should take the second - hand housing market as the main direction, startingwith the sale price and influencing factors of new houses. At the same time, in different cities,we should adhere to the city＇ s policies, reflect the policy differentiation, promote the reformof the real estate supply side, and promote the return of housing properties.
文摘Three-year investigation was conducted to demonstrate the mechanism of reduction of soybean yield aroused by continuous and every second year cropping. Compared to normal cropping, there are many unfavorable changes in some major elements of soybean plant and soil environment. Chloropyll content was lower. Phosphorous content of soybean plant was decreased seriously. Potassium content was lower while calcium content was higher. Magnesium content was wot affected and decreased in susceptive varieties. Some deseases and insects of soybean under continuous and wery second year cropping conditions became serious as continuous years prolonged. Organic matter content tended to go down from normal rotation to continuous cropping. Amount of bacteria and antinomyces decreased while amount of fungi increased. The development of symbiotic nitrogen fixation system wsa deteriorated.
基金one result of the National Social Science Fund Youth Project “Study on ‘X Generation’ from The Perspective of Social Mobility” (ID:13CSH021)National Social Science Fund Major Project “Investigation on Interest Demands and Ideological State of Different Social Groups”(ID:14ZDA059)
文摘Over the past decade the social structure of China has undergone profound changes. The vertical social mobility between social classes tended to slow down and the social structures and stratification became solidified. Phrases such as "second generation of the rich,""second generation of officials,"and "second generation of the farmers"appeared frequently on the Internet and other media,which to some extent reflect the trend in social structure. However,little research has been conducted to address these issues in recent years.This field is in great need of systematic and authoritative surveys and studies on social fragmentation,marginalization,stratification,and mobility.
基金Projects(50490274 , 10472134 , 50404010) supported by the National Natural Science Foundation of China project(2002CB412703) supported by the Key Fundamental Research and Development Programof China
文摘A method to estimate the probabilistic density function （PDF） of shear strength parameters was proposed. The second Chebyshev orthogonal polynomial（SCOP） combined with sample moments （the origin moments） was used to approximate the PDF of parameters. X^2 test was adopted to verify the availability of the method. It is distribution-free because no classical theoretical distributions were assumed in advance and the inference result provides a universal form of probability density curves. Six most commonly-used theoretical distributions named normal, lognormal, extreme value Ⅰ , gama, beta and Weibull distributions were used to verify SCOP method. An example from the observed data of cohesion c of a kind of silt clay was presented for illustrative purpose. The results show that the acceptance levels in SCOP are all smaller than those in the classical finite comparative method and the SCOP function is more accurate and effective in the reliability analysis of geotechnical engineering.
基金supported by the National Natu-ral Science Foundation of China(Grants No.12174220 and No.12074217)the Shandong Provincial Science Foundation for Excellent Young Scholars(Grant No.ZR2023YQ001)+1 种基金the Taishan Young Scholar Program of Shandong Provincethe Qilu Young Scholar Pro-gram of Shandong University.
文摘Higher-order band topology not only enriches our understanding of topological phases but also unveils pioneering lower-dimensional boundary states,which harbors substantial potential for next-generation device applications.The distinct electronic configurations and tunable attributes of two-dimensional materials position them as a quintessential platform for the realization of second-order topological insulators(SOTIs).This article provides an overview of the research progress in SOTIs within the field of two-dimensional electronic materials,focusing on the characterization of higher-order topological properties and the numerous candidate materials proposed in theoretical studies.These endeavors not only enhance our understanding of higher-order topological states but also highlight potential material systems that could be experimentally realized.
文摘Based on the theoretical origin of sociocultural views,this paper reviews second language writing from the sociocultural perspective in recent years and puts forw ard suggestions for the follow-up study. Research from the sociocultural perspective adopts the overall qualitative research methods,with the sociocultural theories and dialogue theories being the framework,attaching importance to the writing process and social context,and concludes that the theoretical basis,research emphasis and methodology still needs perfection.
基金funded by the key project of humanities and social sciences of Anhui education department of China titled with“Study on individual and environmental factors influencing the development of learner autonomy of college students”(2010 JKXM082)
文摘The role that information technology plays in foreign language teaching is no longer confined to assisting teachers to impart knowledge. This paper aims at construction of new English teaching model based on information technology. The author adopted ethnographic research to observe 8 classes and the findings of this study suggest that until frontline teachers deepen their understanding of information technology and change their philosophy of teaching can a successful implementation of the new teaching model be ensured.
文摘The Snows of Kilimanjaro,written by Ernest Hemingway,embodies his writing style typically.The paper focuses on elaborating it from narrative person so that we can grasp and master the theme—beginning is the end,the end is the beginning.
文摘More focuses of foreign language teaching theory and practice are on the study of first language and second language acquisition. The article deals with the concept of first and second language acquisition, the relationship between them and the factors influencing on them. The characteristics of the children acquisition and adult acquisition are also studied.
基金the National Key Laboratory of Metrology and Calibration Technology
文摘A finite domain time difference （FDTD） and second-derivative combined method is proposed for the evaluation of phase center in the Fresnel region of complex structure millimeter antennas. This method adopts FDTD＇s near to far field transformation to obtain the fields in Fresnel region and then applies the second-derivative method to calculate the phase center. The adoption of FDTD efficiently overcomes the difficulties arising from the existing calculation methods＇ requirements for the radiation analytical formula of some complex antennas, which makes the existing second-derivative method more applicable in engineering. Also, FDTD increases the precision owing to the superposition field calculation from its extrapolation. The correctness of this proposed method is certified with typical examples and the phase center in the Fresnel region of a microwave radiometry calibration corrugate horn antenna is evaluated with the key features.
基金supported by the National Nature Science Foundation of China (60472101)President Award of ChineseAcademy of Sciences(O729031511).
文摘Adaptive broadband beamforraing is a key issue in array applications. The adaptive broadband beamformer with tapped delay line （TDL） structure for nonuniform linear array （NLA） is designed according to the rule of minimizing the beamformer＇s output power while keeping the distortionless response （DR） in the direction of desired signal and keeping the constant beamwidth （CB） with the prescribed sidelobe level over the whole operating band. This kind of beamforming problem can be solved with the interior-point method after being converted to the form of standard second order cone programming （SOCP）. The computer simulations are presented which illustrate the effectiveness of our beamformer.
基金supported by the National Natural Science Foundation of China(6067309760702062)+3 种基金the National HighTechnology Research and Development Program of China(863 Program)(2008AA01Z1252007AA12Z136)the National ResearchFoundation for the Doctoral Program of Higher Education of China(20060701007)the Program for Cheung Kong Scholarsand Innovative Research Team in University(IRT 0645).
文摘To preserve the sharp features and details of the synthetic aperture radar （SAR） image effectively when despeckling, a despeckling algorithm with edge detection in nonsubsampled second generation bandelet transform （NSBT） domain is proposed. First, the Canny operator is utilized to detect and remove edges from the SAR image. Then the NSBT which has an optimal approximation to the edges of images and a hard thresholding rule are used to approximate the details while despeckling the edge-removed image. Finally, the removed edges are added to the reconstructed image. As the edges axe detected and protected, and the NSBT is used, the proposed algorithm reaches the state-of-the-art effect which realizes both despeckling and preserving edges and details simultaneously. Experimental results show that both the subjective visual effect and the mainly objective performance indexes of the proposed algorithm outperform that of both Bayesian wavelet shrinkage with edge detection and Bayesian least square-Gaussian scale mixture （BLS-GSM）.
