The 2-dimensional equivalent model used in helicopter ground resonance analysis is convenient for its simplicity and clarity. The equivalent body mass, the stiffness and the damping are derived from the modal charaCte...The 2-dimensional equivalent model used in helicopter ground resonance analysis is convenient for its simplicity and clarity. The equivalent body mass, the stiffness and the damping are derived from the modal charaCteristics. In this paper, a 3-dimensional space model is constructed to analyse the ground resonance.There is little difference between the calculated results of the 2-dimensional equivalent model and those of the 3-dimensional space model. Hence, the 2-dimensional model is verified for the practical application. Generally, the linear lead-lag damping of the equivalent rotor blade at the modal frequency is derived from the lead-lag damper characteristics by a procedure of iteration. The transformation of the imaginary part of the complex modulus of the viscoelastic damper into a linear velocity damping is complicated in analysis. A method to use the complex modulus directly in the ground resonance analysis is derived and verified.展开更多
The feasibility of semi solid processing of hypereutectic A390 alloys using a novel rheoforming process was investigated. A combination of the swirl enthalpy equilibration device (SEED) process, isothermal holding u...The feasibility of semi solid processing of hypereutectic A390 alloys using a novel rheoforming process was investigated. A combination of the swirl enthalpy equilibration device (SEED) process, isothermal holding using insulation and addition of solid alloy during swirling was introduced as a novel method to improve the processability of semi solid slurry. The effects of isothermal holding and the addition of solid alloy on the temperature gradient between the centre and the wall and on the formation of a(Al) particles were examined. In additional tests, phosphorus and strontium were added to the molten metal to refine the primary and eutectic silicon structure to facilitate semi solid processing. The results show that the combination of the SEED process with two additional processing steps can produce semi-solid A390 alloys that can be rheoprocessed. The microstructure reveals an adequate amount of non-dendritic a(Al) globules surrounded by liquid, which greatly improves the processability of semi-solid slurry.展开更多
Mg-4 Li-3(Al-Si),Mg-8 Li-3(Al-Si)and Mg-12 Li-3(Al-Si)alloys based on theα-Mg,α-Mg+β-Li,β-Li phases,respectively,were produced to investigate the effect of alloying with Al-Si eutectic on the microstructure and me...Mg-4 Li-3(Al-Si),Mg-8 Li-3(Al-Si)and Mg-12 Li-3(Al-Si)alloys based on theα-Mg,α-Mg+β-Li,β-Li phases,respectively,were produced to investigate the effect of alloying with Al-Si eutectic on the microstructure and mechanical properties of the three alloys.Alloying with the Al-Si eutectic of Mg-xLi(x=4,8 and 12 wt.%)alloys caused the formation of different types of Al-Li precipitates:Al3Li,AlLi and Li3Al2,respectively.Also,considerable quantities of Mg2Si phase particles were found in the three alloys.The results of tensile tests showed that the Mg-4Li-3(Al-Si)alloy exhibited the highest ultimate tensile strength(UTS)of 249 MPa but the lowest elongation of 6.3%.The Mg-12Li-3(Al-Si)alloy had the highest elongation of 26%but the lowest UTS of 173 MPa.The different mechanical properties were attributed to the different crystal structures of the three alloys and the precipitate with different type,morphology and distribution.展开更多
The copolymerization of CO and styrene catalyzed by Pd/C toward the formation of polyketones (PK)was studied in the N-valeronitrile-N'-methylimidazolium hexafluorophosphate ([C4CNmim]+PF6-) medium. The synth...The copolymerization of CO and styrene catalyzed by Pd/C toward the formation of polyketones (PK)was studied in the N-valeronitrile-N'-methylimidazolium hexafluorophosphate ([C4CNmim]+PF6-) medium. The synthe-sized PK was characterized by Fourier transform infrared(FTIR), elemental analysis, 13C-nuclear magnetic resonance (13C-NMR), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and gel permeation chro-matography (GPC). The supported ionic liquid film on the surface of Pd/C catalyst can prevent the products from covering the hole of active carbon due to its chemical stability and weak coordination ability with metal ions, and thus efficiently improve the catalytic activity. The effects of different amounts of ionic liquid on the catalytic activity and reusability of the catalyst and the molecular weight of PK were discussed. When the usage of ionic liquid is 10wt%(0.1 g ionic liquid/1 g active carbon carrier) and the theoretical content of Pd2+is 5wt%(0.05 g Pd2+/1 g active car-bon carrier), the highest catalytic activity 2 963.64 gSTCO/(gPd·h) is achieved with the molecular weight and polydispersity index of PK as Mn=9 684, Mw=13 452 and Mw/Mn=1.389.展开更多
Aiming atthe pricing of primary agricultural products for the large-scale suppliers and the wholesalers in agri-supply chain management, an approach for the large-scale supplier pricing is presented based on the thres...Aiming atthe pricing of primary agricultural products for the large-scale suppliers and the wholesalers in agri-supply chain management, an approach for the large-scale supplier pricing is presented based on the threshold cointegration method of wholesale prices online including the GBand-TAR modified Band-TAR model. Our empirical work shows that it is more appropriate for a large-scale supplier pricing with his wholesalers based on the threshold cointegration method than the conventional linear cointegration method in spatially separate markets in an agri-supply chain of soybean in China in short time. Firstly, the three pairs of prices in spatially separate markets are of long-run equilibrium and threshold cointegration. The forecast wst shows that the threshold cointegration approach is superior to the conventional linear cointegration approach in short time. Secondly, there are two thresholds of GBand-TAR in which the threshold parameters represent relative transaction costs. Larger thresholds or wider neutral band corresponds to the greater distance between markets. Thirdly, the estimation of M-TAR shows that the large-scale supplier is more sensitive to increase of wholesaler prices than decrease of wholesaler prices. The supplier can price on the forecast of market price by the threshold ECM including the GBand-TAR if the equilibrium error of threshold lag is not in the interval of thresholds in which there is not profitable trading opportunities for the supplier.展开更多
Three ionic liquids(ILs),1-ethyl-3-methylimidazolium bromine([EMIM]Br),1-butyl-3-methylimidazolium bromine([BMIM]Br),and 1-hexyl-3-methylimidazolium bromine([HMIM]Br),were used as the solvent for separation of {tert-b...Three ionic liquids(ILs),1-ethyl-3-methylimidazolium bromine([EMIM]Br),1-butyl-3-methylimidazolium bromine([BMIM]Br),and 1-hexyl-3-methylimidazolium bromine([HMIM]Br),were used as the solvent for separation of {tert-butyl alcohol(TBA)+ water} azeotrope.Vapor–liquid equilibrium(VLE)data for {TBA + water + IL}ternary systems were measured at 101.3 k Pa.The results indicate that all the three ILs produce an obvious effect on the VLE behavior of {TBA + water} system and eliminate the azeotropy in the whole concentration range.[EMIM]Br is the best solvent for the separation of {TBA + water} system by extractive distillation among the three ILs.The experimental VLE data for the ternary systems are correlated with the NRTL model equation with good correlations.Explanations are given with activity coefficients of water and TBA,and the experimental VLE-temperature data for {TBA or water + IL} binary systems.展开更多
The time has come for the constitution of the Association of Southeast Asian Nations (ASEAN) economic community and many facts have been analyzed regarding this topic. This paper presents the results of the statisti...The time has come for the constitution of the Association of Southeast Asian Nations (ASEAN) economic community and many facts have been analyzed regarding this topic. This paper presents the results of the statistical analysis applied to several economic parameters which firstly show how their integration pattern adjusts with a considerable good fitting to the optimum currency area model and to its extended version by Behrens; and secondly how the 10 members of this group are moving at relatively same speed in spite of their differences, that are also inferred for ranging.展开更多
Although the Cointegration Theory was founded by the C.W.J Granger and other economists in the 1980s, it was not widely used in China until C.W.J Granger was awarded with Nobel Prize in 2003. Since then, a lot of econ...Although the Cointegration Theory was founded by the C.W.J Granger and other economists in the 1980s, it was not widely used in China until C.W.J Granger was awarded with Nobel Prize in 2003. Since then, a lot of economic papers introducing or applying Cointegration Theory have emerged, but the phenomenon of misuse of this theory possibly arose at the same time. Based on some of these papers obtained from web site (www.cnki.net), this paper explores the applications of Cointegration Theory in China and draws some initial conclusions. Most of these applications are reasonable, but some of them are a bit blindfold or even contradictory in conclusions, which indicates that the overall application quality has a large room to get improved and should be paid more attention by academe.展开更多
As a growing number of countries, including both developed and developing countries, have in recent yearstaken environmental regulation at different levels, a question of great concern has been raised: can the regulat...As a growing number of countries, including both developed and developing countries, have in recent yearstaken environmental regulation at different levels, a question of great concern has been raised: can the regulation alterthe existing trade volume and trade pattern, and ultimately drive pollution-intensive industries to countries with low-levelregulations or even those without regulations at all? Starting from the three different propositions concerning therelationship between environmental regulation and trade pattern, this paper applies cointegration analysis and errorcorrection model to empirically testing the relationship between environmental regulation and trade in China during theperiod of 1985-2005. Our empirical results indicate that in the short run the collection of pollution discharge fees bearsa positive impact on the export share of clean products of total exports. Thus, higher pollution discharge fees raise theratio of clean products exports to total exports. This further indicates that more stringent environmental regulationpromotes the exports of clean products. In the long run pollution discharge fees are positively correlated with the exportshare of clean products but negatively associated with their import share. Such correlations imply that environmentalregulation tends to facilitate the international specialization in line with comparative advantages.展开更多
The carboxyl terminal of sodium oleate has a stronger polarity than that of oleic acid;this terminal is more likely to be dipole polarized and ionically conductive in a microwave field.Sodium oleate was used as the mo...The carboxyl terminal of sodium oleate has a stronger polarity than that of oleic acid;this terminal is more likely to be dipole polarized and ionically conductive in a microwave field.Sodium oleate was used as the model compound to study the decarboxylation of oleic acid leading to hydrocarbon formation via microwave-assisted pyrolysis technology.The pyrolysis gas,liquid,and solid products were precisely analyzed to deduce the mechanism for decarboxylation of sodium oleate.Microwave energy was able to selectively heat the carboxyl terminal of sodium oleate.During decarboxylation,the double bond in the long hydrocarbon chain formed a p-πconjugated system with the carbanion intermediate.The resulting p-πconjugated system was more stable and beneficial to the pyrolysis reaction(decarboxylation,terminal allylation,isomerization,and aromatization).The physical properties of pyrolysis liquid were generally similar to those of diesel fuel,thereby demonstrating the possible use of microwaves for controlling the decarboxylation of sodium oleate in order to manufacture renewable hydrocarbon fuels.展开更多
Organic solar cells with stacked bulk heterojutaction(BHJ) are investigated based on conjugated polymer. By using the solution spin-coating method, Poly[2-methoxy, 5-(2' -ethyl-hexyloxy) -1,4-phenylene vinylene] ...Organic solar cells with stacked bulk heterojutaction(BHJ) are investigated based on conjugated polymer. By using the solution spin-coating method, Poly[2-methoxy, 5-(2' -ethyl-hexyloxy) -1,4-phenylene vinylene] (MEH-PPV) and ZnO nanoparticles (50 nm) are mixed as the optical sense layer. Ag is used as inter-layer to connect the upper BHJ cell and the lower cell. The structures are ITO/PEDOT:PSS/MEH-PPV lAg / MEH-PPV:ZnO/Al. The open circuit voltage (Voc) of a stacked cell is about 3.7 times of that of an individual organic solar cell (ITO/PEDOT:PSS/MEH-PPV/Al). The short circuit current (Jsc) of a stacked cell is increased by about 1.6 times of that of individual one.展开更多
A magnetic field was used to directional solidification of dendritic Al-Cu alloys. The primary arm spacing of the dendrites is increased with increasing the external magnetic field strength. This microstructural coars...A magnetic field was used to directional solidification of dendritic Al-Cu alloys. The primary arm spacing of the dendrites is increased with increasing the external magnetic field strength. This microstructural coarsening is related to the thermoelectric current on the l/s interface, which is induced by difference of temperature on the inter- face. Within a magnetic field Lorentz force may be generated in front of the interface, causing a thermoelectric-magneto convection that makes the microstructure coarsened. This induced convection also leads to structural instability so that the secondary arms are well developed when grown in the external field.展开更多
A tri-block copolymer coupling agent polystyreneblock-poly (n-butyl-acrylate)-block-poly (y-methacryloxypro pylt rimethoxysilane)(PS-b-PnBA-b-PMPS) was synthesized by atom transfer radical polymerization (ATRP...A tri-block copolymer coupling agent polystyreneblock-poly (n-butyl-acrylate)-block-poly (y-methacryloxypro pylt rimethoxysilane)(PS-b-PnBA-b-PMPS) was synthesized by atom transfer radical polymerization (ATRP), and its molecular structure was characterized by fourier-transform infrared spectra, hydrogen nuclear magnetic resonance and gel permeation chromatography. The glass bead was treated with the block copolymer coupling agent, and then studied by transmission electron microscopy. The result showed that strong interaction was formed between the block copolymer coupling agent and the surface of glass bead, and then the block of poly(n-butylacrylate) formed a layer of film on the surface.展开更多
The organic π-conjugate d polymers are of major interest materials for the use in electro-optical and no nlinear optical devices. In this work, for a selected polyacetylene chain, the optical absorption spectra in UV...The organic π-conjugate d polymers are of major interest materials for the use in electro-optical and no nlinear optical devices. In this work, for a selected polyacetylene chain, the optical absorption spectra in UV/Vis regime as well as the linear polarizabiliti y and nonlinear hyperpolarizability are calculated by using quantum chemical ab initio and semiempirical methods. The relationship of its optical property to el ectric field is obtained. Some physical mechanism of electric field effect on mo lecular optical property is discussed by means of electron distribution and intr amolecular charge transfer.展开更多
For the investigation of mechanical properties of the bimrocks with high rock block proportion,a series of laboratory experiments,including resonance frequency and uniaxial compressive tests,are conducted on the 64 fa...For the investigation of mechanical properties of the bimrocks with high rock block proportion,a series of laboratory experiments,including resonance frequency and uniaxial compressive tests,are conducted on the 64 fabricated bimrocks specimens.The results demonstrate that dynamic elastic modulus is strongly correlated with the uniaxial compressive strength,elastic modulus and block proportions of the bimrocks.In addition,the density of the bimrocks has a good correlation with the mechanical properties of cases with varying block proportions.Thus,three crucial indices(including matrix strength)are used as basic input parameters for the prediction of the mechanical properties of the bimrocks.Other than adopting the traditional simple regression and multi-regression analyses,a new prediction model based on the optimized general regression neural network(GRNN)algorithm is proposed.Note that,the performance of the multi-regression prediction model is better than that of the simple regression model,owing to the consideration of various influencing factors.However,the comparison between model predictions indicates that the optimized GRNN model performs better than the multi-regression model does.Model validation and verification based on fabricated data and experimental data from the literature are performed to verify the predictability and applicability of the proposed optimized GRNN model.展开更多
In recent years, the preservation of fruits and vegetables in cold storage has become an issue of increasing concern, ethylene plays a leading role among them. We found ZnO has the effect of degrading gaseous ethylene...In recent years, the preservation of fruits and vegetables in cold storage has become an issue of increasing concern, ethylene plays a leading role among them. We found ZnO has the effect of degrading gaseous ethylene, however its effect is not particularly satisfactory. Therefore, we used simple photo-deposition procedure and low-temperature calcination method to synthesize Au, Ag, and Au Ag alloy supported ZnO to improve the photocatalytic efficiency. Satisfactorily, after ZnO loaded with sole Au or Ag particles, the efficiency of ethylene degradation was 17.5 and 26.8 times than that of pure ZnO, showing a large increase in photocatalytic activity. However, the photocatalytic stability of Ag/ZnO was very poor, because Ag can be easily photooxidized to Ag2O. Surprisingly, when ZnO was successfully loaded with the Au Ag alloy, not only the photocatalytic activity was further improved to 94.8 times than that of pure ZnO, but also the photocatalytic stability was very good after 10 times of cycles. Characterization results explained that the Au-Ag alloy NPs modified ZnO showed great visible-light absorption because of the surface plasmon resonance(SPR) effect. Meanwhile, the higher photocurrent density showed the effective carrier separation ability in Au Ag/ZnO. Therefore, the cooperative action of plasmonic Au Ag bimetallic alloy NPs and efficient carrier separation capability result in the outstanding photoactivity of ethylene oxidation. At the same time, the formation of the alloy produced a new crystal structure different from Au and Ag, which overcomes the problem of poor stability of Ag/ZnO, and finally obtains Au Ag/ZnO photocatalyst with high activity and high stability. This work proposes a new concept of using metal alloys to remove ethylene in actual production.展开更多
A two-dimensional hydrogen-bonded cadmium(II) compound [Cd(dapm)2- (CH3COO)2(H2O)2] (dapm = diaminodiphenylmethane) has been synthesized and characterized by single-crystal X-ray diffraction analysis. It crystallizes ...A two-dimensional hydrogen-bonded cadmium(II) compound [Cd(dapm)2- (CH3COO)2(H2O)2] (dapm = diaminodiphenylmethane) has been synthesized and characterized by single-crystal X-ray diffraction analysis. It crystallizes in monoclinic, space group C2/c with a = 27.572(3), b = 5.5064(5), c = 23.310(2) , = 124.785(1)o, C15H19Cdo.5ON2O3, Mr =331.52, V = 2906.6(5) ?, Z = 4, Dc = 1.515 g/cm3, F(000) = 1368 and = 0.801 mm-1. The final R = 0.0403 and wR = 0.1014 for 1795 observed reflections with I≥4(I). The centrosymmetric Cd(II) is six- coordinated in a distorted octahedral geometry, and the dapm in a trans mode acts as a monoden- tate ligand. The intermolecular hydrogen bonds among coordinated aqua molecules with coordi- nated acetate oxygen atoms and uncoordinated dapm nitrogen atoms form a two-dimensional supramolecular framework.展开更多
A novel chain complex was synthesized and its crystal structure has been deter- mined by X-ray diffraction technique. It was found that the local coordination geometry around Cu(Ⅱ) is a distorted tetrahedron and C14H...A novel chain complex was synthesized and its crystal structure has been deter- mined by X-ray diffraction technique. It was found that the local coordination geometry around Cu(Ⅱ) is a distorted tetrahedron and C14H9CuNO3CH3OH is bridged by the carboxylate oxygen atom to form an infinite one-dimensional linear chain. The hydrogen bond exists between O(1) and solvate molecule O(4). The crystal belongs to monoclinic, space group P21 with a = 9.6650(19), b = 7.1280(14), c = 9.925(2) ? b = 98.39(3)? V = 676.4(2) 3, Z = 2, F(000) = 342 and m(MoK? = 1.629 mm-1 .展开更多
文摘The 2-dimensional equivalent model used in helicopter ground resonance analysis is convenient for its simplicity and clarity. The equivalent body mass, the stiffness and the damping are derived from the modal charaCteristics. In this paper, a 3-dimensional space model is constructed to analyse the ground resonance.There is little difference between the calculated results of the 2-dimensional equivalent model and those of the 3-dimensional space model. Hence, the 2-dimensional model is verified for the practical application. Generally, the linear lead-lag damping of the equivalent rotor blade at the modal frequency is derived from the lead-lag damper characteristics by a procedure of iteration. The transformation of the imaginary part of the complex modulus of the viscoelastic damper into a linear velocity damping is complicated in analysis. A method to use the complex modulus directly in the ground resonance analysis is derived and verified.
基金the financial support provided by the Natural Sciences and Engineering Research Council of Canada (NSERC) and Rio Tinto Alcan through the NSERC Industrial Research Chair in Metallurgy of Aluminum Transformation at Université du Québec à Chicoutimi
文摘The feasibility of semi solid processing of hypereutectic A390 alloys using a novel rheoforming process was investigated. A combination of the swirl enthalpy equilibration device (SEED) process, isothermal holding using insulation and addition of solid alloy during swirling was introduced as a novel method to improve the processability of semi solid slurry. The effects of isothermal holding and the addition of solid alloy on the temperature gradient between the centre and the wall and on the formation of a(Al) particles were examined. In additional tests, phosphorus and strontium were added to the molten metal to refine the primary and eutectic silicon structure to facilitate semi solid processing. The results show that the combination of the SEED process with two additional processing steps can produce semi-solid A390 alloys that can be rheoprocessed. The microstructure reveals an adequate amount of non-dendritic a(Al) globules surrounded by liquid, which greatly improves the processability of semi-solid slurry.
基金Projects(51971040,51701029,51671041,51531002) supported by the National Natural Science Foundation of ChinaProject(2016YFB0301100) supported by the National Key Research and Development Program of China+2 种基金Projects(2018T110943,2017M620410) supported by the China Postdoctoral Science FoundationProject(Xm2017010) supported by the the Chongqing Postdoctoral Scientific Research Foundation,ChinaProject(2018CDGFCL005) supported by the Fundamental Research Funds for the Central Universities,China
文摘Mg-4 Li-3(Al-Si),Mg-8 Li-3(Al-Si)and Mg-12 Li-3(Al-Si)alloys based on theα-Mg,α-Mg+β-Li,β-Li phases,respectively,were produced to investigate the effect of alloying with Al-Si eutectic on the microstructure and mechanical properties of the three alloys.Alloying with the Al-Si eutectic of Mg-xLi(x=4,8 and 12 wt.%)alloys caused the formation of different types of Al-Li precipitates:Al3Li,AlLi and Li3Al2,respectively.Also,considerable quantities of Mg2Si phase particles were found in the three alloys.The results of tensile tests showed that the Mg-4Li-3(Al-Si)alloy exhibited the highest ultimate tensile strength(UTS)of 249 MPa but the lowest elongation of 6.3%.The Mg-12Li-3(Al-Si)alloy had the highest elongation of 26%but the lowest UTS of 173 MPa.The different mechanical properties were attributed to the different crystal structures of the three alloys and the precipitate with different type,morphology and distribution.
基金Supported by the Tianjin Natural Science Foundation(No.07JCYBJC00600)
文摘The copolymerization of CO and styrene catalyzed by Pd/C toward the formation of polyketones (PK)was studied in the N-valeronitrile-N'-methylimidazolium hexafluorophosphate ([C4CNmim]+PF6-) medium. The synthe-sized PK was characterized by Fourier transform infrared(FTIR), elemental analysis, 13C-nuclear magnetic resonance (13C-NMR), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and gel permeation chro-matography (GPC). The supported ionic liquid film on the surface of Pd/C catalyst can prevent the products from covering the hole of active carbon due to its chemical stability and weak coordination ability with metal ions, and thus efficiently improve the catalytic activity. The effects of different amounts of ionic liquid on the catalytic activity and reusability of the catalyst and the molecular weight of PK were discussed. When the usage of ionic liquid is 10wt%(0.1 g ionic liquid/1 g active carbon carrier) and the theoretical content of Pd2+is 5wt%(0.05 g Pd2+/1 g active car-bon carrier), the highest catalytic activity 2 963.64 gSTCO/(gPd·h) is achieved with the molecular weight and polydispersity index of PK as Mn=9 684, Mw=13 452 and Mw/Mn=1.389.
基金the Social Science Fund Program of Heilongjiang Province in China(Grant No.03B028)
文摘Aiming atthe pricing of primary agricultural products for the large-scale suppliers and the wholesalers in agri-supply chain management, an approach for the large-scale supplier pricing is presented based on the threshold cointegration method of wholesale prices online including the GBand-TAR modified Band-TAR model. Our empirical work shows that it is more appropriate for a large-scale supplier pricing with his wholesalers based on the threshold cointegration method than the conventional linear cointegration method in spatially separate markets in an agri-supply chain of soybean in China in short time. Firstly, the three pairs of prices in spatially separate markets are of long-run equilibrium and threshold cointegration. The forecast wst shows that the threshold cointegration approach is superior to the conventional linear cointegration approach in short time. Secondly, there are two thresholds of GBand-TAR in which the threshold parameters represent relative transaction costs. Larger thresholds or wider neutral band corresponds to the greater distance between markets. Thirdly, the estimation of M-TAR shows that the large-scale supplier is more sensitive to increase of wholesaler prices than decrease of wholesaler prices. The supplier can price on the forecast of market price by the threshold ECM including the GBand-TAR if the equilibrium error of threshold lag is not in the interval of thresholds in which there is not profitable trading opportunities for the supplier.
基金Supported by the National Natural Science Foundation of China(21076126)the Program for Liaoning Excellent Talents in University(2012013)the Liaoning Province Science Foundation of China(2014020140)
文摘Three ionic liquids(ILs),1-ethyl-3-methylimidazolium bromine([EMIM]Br),1-butyl-3-methylimidazolium bromine([BMIM]Br),and 1-hexyl-3-methylimidazolium bromine([HMIM]Br),were used as the solvent for separation of {tert-butyl alcohol(TBA)+ water} azeotrope.Vapor–liquid equilibrium(VLE)data for {TBA + water + IL}ternary systems were measured at 101.3 k Pa.The results indicate that all the three ILs produce an obvious effect on the VLE behavior of {TBA + water} system and eliminate the azeotropy in the whole concentration range.[EMIM]Br is the best solvent for the separation of {TBA + water} system by extractive distillation among the three ILs.The experimental VLE data for the ternary systems are correlated with the NRTL model equation with good correlations.Explanations are given with activity coefficients of water and TBA,and the experimental VLE-temperature data for {TBA or water + IL} binary systems.
文摘The time has come for the constitution of the Association of Southeast Asian Nations (ASEAN) economic community and many facts have been analyzed regarding this topic. This paper presents the results of the statistical analysis applied to several economic parameters which firstly show how their integration pattern adjusts with a considerable good fitting to the optimum currency area model and to its extended version by Behrens; and secondly how the 10 members of this group are moving at relatively same speed in spite of their differences, that are also inferred for ranging.
文摘Although the Cointegration Theory was founded by the C.W.J Granger and other economists in the 1980s, it was not widely used in China until C.W.J Granger was awarded with Nobel Prize in 2003. Since then, a lot of economic papers introducing or applying Cointegration Theory have emerged, but the phenomenon of misuse of this theory possibly arose at the same time. Based on some of these papers obtained from web site (www.cnki.net), this paper explores the applications of Cointegration Theory in China and draws some initial conclusions. Most of these applications are reasonable, but some of them are a bit blindfold or even contradictory in conclusions, which indicates that the overall application quality has a large room to get improved and should be paid more attention by academe.
文摘As a growing number of countries, including both developed and developing countries, have in recent yearstaken environmental regulation at different levels, a question of great concern has been raised: can the regulation alterthe existing trade volume and trade pattern, and ultimately drive pollution-intensive industries to countries with low-levelregulations or even those without regulations at all? Starting from the three different propositions concerning therelationship between environmental regulation and trade pattern, this paper applies cointegration analysis and errorcorrection model to empirically testing the relationship between environmental regulation and trade in China during theperiod of 1985-2005. Our empirical results indicate that in the short run the collection of pollution discharge fees bearsa positive impact on the export share of clean products of total exports. Thus, higher pollution discharge fees raise theratio of clean products exports to total exports. This further indicates that more stringent environmental regulationpromotes the exports of clean products. In the long run pollution discharge fees are positively correlated with the exportshare of clean products but negatively associated with their import share. Such correlations imply that environmentalregulation tends to facilitate the international specialization in line with comparative advantages.
基金the National Natural Science Foundation of China(No.21266022)the National High Technology Research and Development Program 863(2012AA101800-03+4 种基金2012AA02120562012AA021704)the International Cooperation of Jiangxi Province(No.20101208)the International Science & Technology Cooperation Program of China(No.2010DFB63750)the Natural Science Foundation of Jiangxi Province(No.2008GZH0047)
文摘The carboxyl terminal of sodium oleate has a stronger polarity than that of oleic acid;this terminal is more likely to be dipole polarized and ionically conductive in a microwave field.Sodium oleate was used as the model compound to study the decarboxylation of oleic acid leading to hydrocarbon formation via microwave-assisted pyrolysis technology.The pyrolysis gas,liquid,and solid products were precisely analyzed to deduce the mechanism for decarboxylation of sodium oleate.Microwave energy was able to selectively heat the carboxyl terminal of sodium oleate.During decarboxylation,the double bond in the long hydrocarbon chain formed a p-πconjugated system with the carbanion intermediate.The resulting p-πconjugated system was more stable and beneficial to the pyrolysis reaction(decarboxylation,terminal allylation,isomerization,and aromatization).The physical properties of pyrolysis liquid were generally similar to those of diesel fuel,thereby demonstrating the possible use of microwaves for controlling the decarboxylation of sodium oleate in order to manufacture renewable hydrocarbon fuels.
基金the National Natural Science Foundation of China ( 60576016 and 10774013)National "863" Program (2006AA03Z0412)"973" Program(2003CB314707)
文摘Organic solar cells with stacked bulk heterojutaction(BHJ) are investigated based on conjugated polymer. By using the solution spin-coating method, Poly[2-methoxy, 5-(2' -ethyl-hexyloxy) -1,4-phenylene vinylene] (MEH-PPV) and ZnO nanoparticles (50 nm) are mixed as the optical sense layer. Ag is used as inter-layer to connect the upper BHJ cell and the lower cell. The structures are ITO/PEDOT:PSS/MEH-PPV lAg / MEH-PPV:ZnO/Al. The open circuit voltage (Voc) of a stacked cell is about 3.7 times of that of an individual organic solar cell (ITO/PEDOT:PSS/MEH-PPV/Al). The short circuit current (Jsc) of a stacked cell is increased by about 1.6 times of that of individual one.
基金Supported by LTU Foundations of Science and Technology
文摘A magnetic field was used to directional solidification of dendritic Al-Cu alloys. The primary arm spacing of the dendrites is increased with increasing the external magnetic field strength. This microstructural coarsening is related to the thermoelectric current on the l/s interface, which is induced by difference of temperature on the inter- face. Within a magnetic field Lorentz force may be generated in front of the interface, causing a thermoelectric-magneto convection that makes the microstructure coarsened. This induced convection also leads to structural instability so that the secondary arms are well developed when grown in the external field.
文摘A tri-block copolymer coupling agent polystyreneblock-poly (n-butyl-acrylate)-block-poly (y-methacryloxypro pylt rimethoxysilane)(PS-b-PnBA-b-PMPS) was synthesized by atom transfer radical polymerization (ATRP), and its molecular structure was characterized by fourier-transform infrared spectra, hydrogen nuclear magnetic resonance and gel permeation chromatography. The glass bead was treated with the block copolymer coupling agent, and then studied by transmission electron microscopy. The result showed that strong interaction was formed between the block copolymer coupling agent and the surface of glass bead, and then the block of poly(n-butylacrylate) formed a layer of film on the surface.
基金Natural Science Foundation from Shandong Province of China (Y2002A06)
文摘The organic π-conjugate d polymers are of major interest materials for the use in electro-optical and no nlinear optical devices. In this work, for a selected polyacetylene chain, the optical absorption spectra in UV/Vis regime as well as the linear polarizabiliti y and nonlinear hyperpolarizability are calculated by using quantum chemical ab initio and semiempirical methods. The relationship of its optical property to el ectric field is obtained. Some physical mechanism of electric field effect on mo lecular optical property is discussed by means of electron distribution and intr amolecular charge transfer.
基金Projects(51978669,U1734208)supported by the National Natural Science Foundation of ChinaProject(2018JJ3657)supported by Natural Science Foundation of Hunan Province,China
文摘For the investigation of mechanical properties of the bimrocks with high rock block proportion,a series of laboratory experiments,including resonance frequency and uniaxial compressive tests,are conducted on the 64 fabricated bimrocks specimens.The results demonstrate that dynamic elastic modulus is strongly correlated with the uniaxial compressive strength,elastic modulus and block proportions of the bimrocks.In addition,the density of the bimrocks has a good correlation with the mechanical properties of cases with varying block proportions.Thus,three crucial indices(including matrix strength)are used as basic input parameters for the prediction of the mechanical properties of the bimrocks.Other than adopting the traditional simple regression and multi-regression analyses,a new prediction model based on the optimized general regression neural network(GRNN)algorithm is proposed.Note that,the performance of the multi-regression prediction model is better than that of the simple regression model,owing to the consideration of various influencing factors.However,the comparison between model predictions indicates that the optimized GRNN model performs better than the multi-regression model does.Model validation and verification based on fabricated data and experimental data from the literature are performed to verify the predictability and applicability of the proposed optimized GRNN model.
文摘In recent years, the preservation of fruits and vegetables in cold storage has become an issue of increasing concern, ethylene plays a leading role among them. We found ZnO has the effect of degrading gaseous ethylene, however its effect is not particularly satisfactory. Therefore, we used simple photo-deposition procedure and low-temperature calcination method to synthesize Au, Ag, and Au Ag alloy supported ZnO to improve the photocatalytic efficiency. Satisfactorily, after ZnO loaded with sole Au or Ag particles, the efficiency of ethylene degradation was 17.5 and 26.8 times than that of pure ZnO, showing a large increase in photocatalytic activity. However, the photocatalytic stability of Ag/ZnO was very poor, because Ag can be easily photooxidized to Ag2O. Surprisingly, when ZnO was successfully loaded with the Au Ag alloy, not only the photocatalytic activity was further improved to 94.8 times than that of pure ZnO, but also the photocatalytic stability was very good after 10 times of cycles. Characterization results explained that the Au-Ag alloy NPs modified ZnO showed great visible-light absorption because of the surface plasmon resonance(SPR) effect. Meanwhile, the higher photocurrent density showed the effective carrier separation ability in Au Ag/ZnO. Therefore, the cooperative action of plasmonic Au Ag bimetallic alloy NPs and efficient carrier separation capability result in the outstanding photoactivity of ethylene oxidation. At the same time, the formation of the alloy produced a new crystal structure different from Au and Ag, which overcomes the problem of poor stability of Ag/ZnO, and finally obtains Au Ag/ZnO photocatalyst with high activity and high stability. This work proposes a new concept of using metal alloys to remove ethylene in actual production.
文摘A two-dimensional hydrogen-bonded cadmium(II) compound [Cd(dapm)2- (CH3COO)2(H2O)2] (dapm = diaminodiphenylmethane) has been synthesized and characterized by single-crystal X-ray diffraction analysis. It crystallizes in monoclinic, space group C2/c with a = 27.572(3), b = 5.5064(5), c = 23.310(2) , = 124.785(1)o, C15H19Cdo.5ON2O3, Mr =331.52, V = 2906.6(5) ?, Z = 4, Dc = 1.515 g/cm3, F(000) = 1368 and = 0.801 mm-1. The final R = 0.0403 and wR = 0.1014 for 1795 observed reflections with I≥4(I). The centrosymmetric Cd(II) is six- coordinated in a distorted octahedral geometry, and the dapm in a trans mode acts as a monoden- tate ligand. The intermolecular hydrogen bonds among coordinated aqua molecules with coordi- nated acetate oxygen atoms and uncoordinated dapm nitrogen atoms form a two-dimensional supramolecular framework.
文摘A novel chain complex was synthesized and its crystal structure has been deter- mined by X-ray diffraction technique. It was found that the local coordination geometry around Cu(Ⅱ) is a distorted tetrahedron and C14H9CuNO3CH3OH is bridged by the carboxylate oxygen atom to form an infinite one-dimensional linear chain. The hydrogen bond exists between O(1) and solvate molecule O(4). The crystal belongs to monoclinic, space group P21 with a = 9.6650(19), b = 7.1280(14), c = 9.925(2) ? b = 98.39(3)? V = 676.4(2) 3, Z = 2, F(000) = 342 and m(MoK? = 1.629 mm-1 .