Based on the survey data of typical villages in Shaanxi Province,China,the effect of social capital on the income gap of farmers' households was analyzed using the Shapley value of the total amount of social capit...Based on the survey data of typical villages in Shaanxi Province,China,the effect of social capital on the income gap of farmers' households was analyzed using the Shapley value of the total amount of social capital and the social capital structure.The results show the following:first,social capital can expand the household income gap,and the effect of this index on the household income gap is 7.54%.Second,the indexes of the social capital dimension can expand the household income gap,and the structural effects of the household income gap on social networks,social trust,and social participation are 3.17%,3.64%,and 0.65%,respectively.Third,no dimension of the path is the same as the effect on the household income gap.展开更多
The stability of a backfill wall is critical to implement gob-side entry driving technology in which a small coal pillar is substituted by a waste backfill wall. Based on features of surrounding rock structures in the...The stability of a backfill wall is critical to implement gob-side entry driving technology in which a small coal pillar is substituted by a waste backfill wall. Based on features of surrounding rock structures in the backfill wall, we propose a mechanical model on the structural effect of a soft-hard backfill wall using theory analysis, physical experiments and a numerical simulation. The results show thatChe deformation of the structure of the soft-hard backfill wall is coordinated with the roof and floor. The soft structure on the top of the backfill wall can absorb the energy in the roof by its large deformation and adapt to the given deformation caused by the rotation and subsidence of a key rock block. The hard structure at the bottom of the backfill wall can absorb the strong supporting resistance from the top surrounding rock. The soft structure on the top protecting the hard bottom structure by its large deformation contributes to the stability of the entire backfill wall. An application indicated that the stress in the backfill wall effec- tively decreased and its deformation was significantly reduced after the top coal remained. This ensured the stability of the backfill wall.展开更多
Through improvements on a fully commercial and automatic system measuring frequency andtemperature spectra of the complex elastic, dielectric, and piezoelectric constants of polymerfilms, the precision for measuring c...Through improvements on a fully commercial and automatic system measuring frequency andtemperature spectra of the complex elastic, dielectric, and piezoelectric constants of polymerfilms, the precision for measuring complex dielectric constants achieved 2‰ from original 1%.The complex dielectric constants of PVDF, VDF （95 ）/VF （5）, VDF （52）/TrFE （48） and VDF（47. 5）/TrFE（47. 5）/HeFP （5） over a range of-120-140℃, 10-2-10;Hz were measured bythe described system. The diminution of chain regularity due to 5mol% vinyl fluoride in the chainof PVDF led to disappearing of α-relaxation and increase in T;（3℃） of VDF （95）/VF （5）.Because of the spatial impediment of 5mol% HeFP in copolymer chain, the Curie point of VDF（52）/TrFE（48） decreased by 30℃ and T;by 3℃. The behavior of dielectric relaxation indicatedthat 5mol% vinyl fluoride and HeFP made the relaxation strength of noncrystalline regionreduced, the activation energy of local relaxation increased and the relaxation time prolonged respectively.展开更多
The struetural effect of the conjugative system(C)with carbonyl-imino bridges has been studied.The results show that:In the conjugated system(C),there is no electronic absorption peak attributable to the whole system,...The struetural effect of the conjugative system(C)with carbonyl-imino bridges has been studied.The results show that:In the conjugated system(C),there is no electronic absorption peak attributable to the whole system,but there are three π-π* bands each nt which displays chacactecistics of its own independently.These indicate that the two bridges-carbonyl-and-imino-can block the tlanSmlSSion of the conjngative polarization of the whole system,so as to form three segments,this is verified by means of chemical synthesis and degradation.展开更多
The 0.8 Me V copper ( Cu) ion beam irradiation-induced effects on structural, morphological and optical properties of tin dioxide nanowires (SnO_(2)NWs) are investigated. The samples are irradiated at three different ...The 0.8 Me V copper ( Cu) ion beam irradiation-induced effects on structural, morphological and optical properties of tin dioxide nanowires (SnO_(2)NWs) are investigated. The samples are irradiated at three different doses 5 × 10^12 ions/cm^(2), 1 ×10^(13) ions/cm^(2) and 5 × 10^(13) ions/em^(2) at room temperature. The XRD analysis shows that the tetragonal phase of SnO_(2)NWs remains stable after Cu ion irradiation, but with increasing irradiation dose level the crystal size increases due to ion beam induced coalescence of NWs. The FTIR spectra of pristine SnO_(2)NWs exhibit the chemical composition of SnO_(2)while the Cn-O bond is also observed in the FTIR spectra after Cu ion beam irradiation. The presence of Cu impurity in SnO_(2)is further confirmed by calculating the stopping range of Cu ions by using TRM/SRIM code. Optical properties of SnO_(2)NWs are studied before and after Cu ion irradiation. Band gap analysis reveMs that the band gap of irradiated samples is found to decrease compared with the pristine sample. Therefore, ion beam irradiation is a promising technology for nanoengineering and band gap tailoring.展开更多
The characteristics and distribution of faults in Yinggehai basin discussed in this paper reveal the structural effects of the overpressure fluid expulsion. The rapid subsidence and mud rich intervals of the marine r...The characteristics and distribution of faults in Yinggehai basin discussed in this paper reveal the structural effects of the overpressure fluid expulsion. The rapid subsidence and mud rich intervals of the marine rocks dominate the formation of the overpressure systems and the enormous volumes of the overpressure fluids in the basin. Triggered by some faults, the overpressure fluids were expulsed rapidly from the overpressure compartments to form a series of diapirs in the basin, resulting in the dense fractures or faults and folds in the limbs of diapirs. These fractures and faults provided the migration pathway for the vertical flow of hydrocarbons, so that the gas fields arising from this process might migrate upwards to the sandstone reservoir. Therefore, the hydrocarbon accumulations are usually located in the upper parts of diapiric structures.展开更多
Structural and magnetic properties are investigated for Fe1-xMnxV2O4 （0≤ x ≤ 1） spinels. As orbital-active Fe^2＋ is substituted with Mn^2＋, the cubie-to-tetragonM transition TsI and the tetragonal-to-orthorhombi...Structural and magnetic properties are investigated for Fe1-xMnxV2O4 （0≤ x ≤ 1） spinels. As orbital-active Fe^2＋ is substituted with Mn^2＋, the cubie-to-tetragonM transition TsI and the tetragonal-to-orthorhombic transition Ts2 gradually decrease. These structural transitions originate from the Fe^2＋ ferro-orbital order （F-OO）. Below Yafet-Kittel （YK） magnetic transition TN2, V^3＋ orbital order （V-OO） plays an important role on global structure. Here x = 0.6 is a critical point. Fe^2＋ F-OO and V^3＋ F-OO coexist for 0 ≤ x ≤ 0.5. For x≥ 0.6, the orbital pattern of V^3＋ is antiferro （AF）-00, and Fe^2＋ F-OO disappears. Structural transition Ts3, accompanied by YK magnetic transition TN2, decreases initially, and then increases at x = 0.6. A scenario for the complex phase diagram arising from the cooperation or competition of Fe^2＋ and V^3＋ orbitals is proposed.展开更多
Undoped and Zn-doped Cu2O films were deposited onto glass substrates using successive ionic layer adsorption and reaction（SILAR） technique with different Zn doping levels（0, 1, 2, 3, 5 and 10 wt%）. The structural,...Undoped and Zn-doped Cu2O films were deposited onto glass substrates using successive ionic layer adsorption and reaction（SILAR） technique with different Zn doping levels（0, 1, 2, 3, 5 and 10 wt%）. The structural,optical, and surface morphological studies were carried out and reported. The structural study revealed that the crystalline quality is gradually enhanced up to 5 wt% of Zn doping level, and then quality begins to degrade for further increase in doping level. Moreover, the preferential orientation changes from（111） to（110） for the highest doping level were examined. Optical study shows that the transmittance（65%） and optical band gap values are maximum（2.41 e V） when the Zn doping level is at 5 wt%. The photoluminescence study confirms the presence of various defects in the Cu2O matrix and also the variation obtained in the optical band gap from the transmittance data. SEM images revealed the annealinginduced changes in the surface morphology of the films.展开更多
Over the period of rainfall, urban green infrastructures(UGI) function like a sponge by absorbing surface runoff as sinks;however, they will shift to sources once their runoff reduction capacities are exceeded. This d...Over the period of rainfall, urban green infrastructures(UGI) function like a sponge by absorbing surface runoff as sinks;however, they will shift to sources once their runoff reduction capacities are exceeded. This dynamic of sink-source shifts, and its dependence on the vegetation structure, remain poorly understood, limiting the action of flood-resilient UGI strategies. This study employs MIKE SHE/11 model coupled with statistical analysis for such resolution. Across four scenarios ranging from light to heavy rainfall, we identified regime shifts in UGI system through the decreasing to increasing trends of sink fractions, typically occurring around 13–18 h after rainfall starts. Based on these regime shifts, we categorized the UGI system into vulnerable, reliable, and recoverable components, highlighting its heterogeneous performance. In addition, by examining the influence of vegetation structure on sink–source dynamics, we found that a higher probability of sinks under light rainfalls was associated with a greater leaf area index(LAI) and vegetation height standard deviation(VHSTD), while green volume(GV) and canopy height(CH) played a more prominent role under heavier rainfalls. Threshold effect analysis further revealed that, a high proportion of the recoverable parts met the thresholds of CH(82 %)and GV(85 %), whereas fewer reached the thresholds of LAI(15 %–19 %) and VHSTD(3 %–6 %). These findings underscore the importance of enhancing 3D vegetation configuration for UGI to adapt to flood impacts. Our study expects to provide actionable knowledge for understanding, quantification, and management of the runoff sink-source dynamics, informing UGI design and planning to achieve urban flood resilience.展开更多
Accurate characterization of three-dimensional burning crack propagation remains pivotal yet challenging for energetic material safety,as conventional diagnostics and models inadequately resolve coupled crack-pressure...Accurate characterization of three-dimensional burning crack propagation remains pivotal yet challenging for energetic material safety,as conventional diagnostics and models inadequately resolve coupled crack-pressure dynamics in confined explosives.This study combines a novel spherical confinement system(with/without sapphire windows)with synchronized high-speed imaging and 3D reconstruction to overcome optical limitations in opaque explosives.Experimental analysis of centrally ignited HMX-based PBX-1 reveals:(1)burning cracks propagate radially with equatorial acceleration and polar deceleration,(2)systematic formation of 3–4 dominant crack branches across geometries,and(3)pressure evolution exhibiting gradual accumulation(subsurface cracking)followed by exponential growth(surface burn-through),with decay governed by cavity expansion.Building on Hill's framework,we develop a model incorporating cavity volume and fracture toughness criteria,validated against PBX explosive(95%HMX-based)experiments.The model demonstrates improved prediction of pressure trends compared to prior approaches,particularly in resolving laminar-phase accumulation and crackinduced surge transitions.Results establish structural cavity volume as a critical modulator of measured pressure and reveal direction-dependent crack kinematics as fundamental features of constrained combustion.This work provides experimentally validated insights into mechanisms of reaction pressure development and burning cracks pathways during constrained PBX explosive combustion.展开更多
An immature pinecone shaped hierarchically structured zirconia （ZrO2-ipch） and a cobblestone-like zirconia nanoparticulate （ZrO2-cs）, both with the monoclinic phase （m-phase）, were synthesized by the facile hydr...An immature pinecone shaped hierarchically structured zirconia （ZrO2-ipch） and a cobblestone-like zirconia nanoparticulate （ZrO2-cs）, both with the monoclinic phase （m-phase）, were synthesized by the facile hydrothermal method and used as the support for a Ni catalyst for the dry reforming of methane （DRM） with CO2. ZrO2-ipch is a much better support than ZrO2-cs and the traditional ZrO2 irregular particles made by a simple precipitation method （ZrO2-ip）. The supported Ni catalyst on ZrO2-ipch （Ni/ZrO2-ipch） exhibited outstanding catalytic activity and coke-resistant stability compared to the ones on ZrO2-cs （Ni/ZrO2-cs） and ZrO2-ip （Ni/ZrO2-ip）. Ni/ZrO2-ip exhibited the worst catalytic performance. The origin of the significantly enhanced catalytic performance was revealed by characterization including XRD, N2 adsorption measurement （BET）, TEM, H2-TPR, CO chemisorption, CO2-TPD, XPS and TGA. The superior catalytic activity of Ni/ZrO2-ipch to Ni/ZrO2-cs or Ni/ZrO2-ip was ascribed to a higher Ni dispersion, increased reducibility, enhanced oxygen mo- bility, and more basic sites with a higher strength, which were due to the unique hierarchically structural morphology of the ZrO2-ipch support. Ni/ZrO2-ipch exhibited better stability for the DRM reaction than Ni/ZrO2-ip, which was ascribed to its higher resistance to Ni sintering due to a strengthened metal-support interaction and the confinement effect of the mesopores and coke deposition resistance. The higher coking resistance of Ni/ZrO2-ipch for the DRM reaction in comparison with Ni/ZrOz-ip orignated from the coke-removalabitity of the higher amount of lattice oxygen and more basic sites, confirmed by XPS and CO2-TPD analysis, and the stabilized Ni on the Ni/ZrO2-ipch catalyst by the confinement effect of the mesopores of the hierarchical ZrO2-ipch sup- port. The superior catalytic performance and coking resistance of the Ni/ZrO2-ipch catalyst makes it a promising candidate for synthesis gas production from the DRM reaction.展开更多
Several MoS2 catalysts of different structure, prepared by in situ decomposition of ammonium heptamolybdate （AHM） and molybdenum naphthenate （MoNaph）, and by MoS2 exfoliation （TDM）, were characterized by BET, X-...Several MoS2 catalysts of different structure, prepared by in situ decomposition of ammonium heptamolybdate （AHM） and molybdenum naphthenate （MoNaph）, and by MoS2 exfoliation （TDM）, were characterized by BET, X-ray diffraction （XRD）, Energy Dispersive X-ray （EDX） and transmission electron microscopy （TEM）. The analysis showed that MoS2 structure was dependant upon the preparation procedure. The activity of the catalysts was determined by measuring the hydrodeoxygenation （HDO） of phenol, 4-methylphenol and 4-methoxyphenol using a batch autoclave reactor operated at 2.8 MPa of hydrogen and temperatures ranging from 320-370℃. By comparing the conversion, the reactivity order of the catalysts was： AHM〉TDM-D〉MoNaph〉thermal〉MoS2 powder〉 TDM-W. Also, the effect of reaction temperature on the HDO conversion was explained in terms of equilibrium of reversible reaction kinetics. The main products of the HDO for phenolic compounds were identified by gas chromatography/mass spectrometry （GC/MS）. The results showed that the product distribution and the HDO selectivity were correlated with the reaction temperature. Two parallel reaction routes, direct hydrogenolysis and combined hydrogenation-hydrogenolysis, were confirmed by the analysis of the product distribution. High temperature favored hydrogenolysis over hydrogenation for HDO of phenol and 4-methoxyphenol, whereas for 4-methylphenol the reverse was true.展开更多
China＇s success in reform and opening up policy for twenty years is regarded as China＇s miracles in the world, whereas the income differential widening phenomenon has been the focus of the policymakers and researche...China＇s success in reform and opening up policy for twenty years is regarded as China＇s miracles in the world, whereas the income differential widening phenomenon has been the focus of the policymakers and researchers. This article researches 1994-2003 China＇s rural regions income differential and its decomposition. The method this paper used to measure the disparity is Gini Index. There are many ways to compute it, so the easiest way to decompose Gini Index-Matrix method is adopted. And based on it, farmer＇s income could be divided into wage income, fanning income, transfer income and property income according to its composition. The conclusion is that all of the indexes are between 0.2 and 0.3, at the comparatively average level. From the fluctuation trend, it increased from 1994 to 1995, while reduced from 1995 to 1996, fluctuated in 1997, and then diminished again. In general, farmer＇s regions income differential stays at comparatively average level, but it has the widening trend with time. Through decomposing Gini Index, wage income is the most important increasing factor, while fanning income is the reducing factor.展开更多
Carbon dioxide emissions have increased due to the consumption of fossil fuels,making the neutralization and utilization of CO_(2) a pressing issue.As a clean and efficient energy conversion process,electrocatalytic r...Carbon dioxide emissions have increased due to the consumption of fossil fuels,making the neutralization and utilization of CO_(2) a pressing issue.As a clean and efficient energy conversion process,electrocatalytic reduction can reduce carbon dioxide into a series of alcohols and acidic organic molecules,which can effectively realize the utilization and transformation of carbon dioxide.This review focuses on the tuning strategies and structure effects of catalysts for the electrocatalytic CO_(2) reduction reaction(CO_(2)RR).The tuning strategies for the active sites of catalysts have been reviewed from intrinsic and external perspectives.The structure effects for the CO_(2)RR catalysts have also been discussed,such as tandem catalysis,synergistic effects and confinement catalysis.We expect that this review about tuning strategies and structure effects can provide guidance for designing highly efficient CO_(2)RR electrocatalysts.展开更多
Hydrogenation of CO_(2) to value-added chemicals has attracted much attention all through the world.In2 O_(3) with cubic bixbyite-type(denoted as c-In2O_(3))is well known for its high CO_(2) hydrogenation activity and...Hydrogenation of CO_(2) to value-added chemicals has attracted much attention all through the world.In2 O_(3) with cubic bixbyite-type(denoted as c-In2O_(3))is well known for its high CO_(2) hydrogenation activity and CH3 OH selectivity at high temperature.However,the other structure of In2O_(3) with rhombohedral corundum-type(denoted as rh-In2O_(3))rarely been investigated as catalyst.Herein,c-In2O_(3) and rh-In2O_(3) were prepared and comparatively studied for CO_(2) hydrogenation.The results indicated that c-In2O_(3) showed higher CO_(2) conversion activity than rh-In2O_(3) due to the impressive reducibility and reactivity.Whereas rh-In2O_(3) had higher CH3 OH selectivity due to weaker CH3 OH and stronger CO adsorption on rhIn2O_(3).Although c-In2O_(3) and rh-In2O_(3) catalysts showed different CO_(2) hydrogenation perfo rmance,in-situ diffuse reflectance infrared Fourier transform spectroscopy showed CO_(2) can be reduced to CO through redox cycling and hydrogenation to CH3 OH through formate path.展开更多
Due to the randomness of earthquake wave magnitude and direction, and the uncertain direction of strong axis and weak axis in the construction of engineering structures, the effect of the direction of ground motion on...Due to the randomness of earthquake wave magnitude and direction, and the uncertain direction of strong axis and weak axis in the construction of engineering structures, the effect of the direction of ground motion on a structure are studied herein. Ground motion records usually contain three vertical ground motion data, which are obtained by sensors arranged in accordance with the EW （East -West） direction, NS （South- North） direction and perpendicular to the surface （z） direction, referring to the construction standard of seismic stations. The seismic records in the EW and NS directions are converted to Cartesian coordinates in accordance with the rotation of θ = 0°-180°, and consequently, a countless group of new ground motion time histories are obtained. Then, the characteristics of the ground motion time history and response spectrum of each group were studied, resulting in the following observations： （1） the peak and phase of ground motion are changed with the rotation of direction θ, so that the direction θ of the maximum peak ground motion can be determined; （2） response spectrum values of each group of ground motions change along with the direction θ, and their peak, predominant period and declining curve are also different as the changes occur; then, the angle θ in the direction of the maximum peak value or the widest predominant period can be determined; and （3） the seismic response of structures with different directions of ground motion inputs has been analyzed under the same earthquake record, and the results show the difference. For some ground motion records, such as the Taft seismic wave, these differences are significant. Next, the Lushan middle school gymnasium structure was analyzed and the calculation was checked using the proposed method, where the internal force of the upper space truss varied from 25% to 28%. The research results presented herein can be used for reference in choosing the ground motion when checking the actual damage to structures following earthquakes and explaining the seismic damage. Meanwhile, it also provides a reference value for research into the most severe ground motion.展开更多
Foam structure materials are well known for their lightweight,efficient,and broadband microwave absorption properties compared to bulk material.However,little has been understood about the effect of a foam structure o...Foam structure materials are well known for their lightweight,efficient,and broadband microwave absorption properties compared to bulk material.However,little has been understood about the effect of a foam structure on the absorption performance of the foam material.In this study,the role of foam structure properties of the silicon carbide/carbon(SiC/C)foam material on microwave absorption is explored using experiment and simulation.We find that the foam structure of SiC/C foam material causes diffraction,multiple reflections,improves the interfacial polarization,and compatibilization.The absorption performance of SiC/C foam material is also studied.The-10 dB effective absorption bandwidth can be adjusted from 4.0 GHz to 18 GHz by tuning SiC/C foam material thickness to 3-7 mm.Therefore,the foam structure design is an effective way to improve the absorption performance of the SiC/C foam material.展开更多
Fischer-Tropsch synthesis （FTS） is an increasingly important approach for producing liquid fuels and chemicals via syngas-that is, synthesis gas, a mixture of carbon monoxide and hydrogen-generated from coal, natura...Fischer-Tropsch synthesis （FTS） is an increasingly important approach for producing liquid fuels and chemicals via syngas-that is, synthesis gas, a mixture of carbon monoxide and hydrogen-generated from coal, natural gas, or biomass. In FTS, dispersed transition metal nanoparticles are used to catalyze the reactions underlying the formation of carbon-carbon bonds. Catalytic activity and selectivity are strongly correlated with the electronic and geometric structure of the nanoparticles, which depend on the particle size, morphology, and crystallographic phase of the nanoparticles. In this article, we review recent works dealing with the aspects of bulk and surface sensitivity of the FTS reaction. Understanding the different catalytic behavior in more detail as a function of these parameters may guide the design of more active, selective, and stable FTS catalysts.展开更多
A novel acrylic monomer bearing aromatic ethereality group N-(p -phenoxy-phenyl) methacrylamide(MAPOA) was synthesized and polymerized. The fluorescence spectra of MAPOA and its polymer were studied, showing that the ...A novel acrylic monomer bearing aromatic ethereality group N-(p -phenoxy-phenyl) methacrylamide(MAPOA) was synthesized and polymerized. The fluorescence spectra of MAPOA and its polymer were studied, showing that the polymer displays a stronger fluorescence than its monomer at the same chromophore concentration. The fluorescence of P(MAPOA) was quenched by adding electron deficiency monomers such as MMA, AN etc .. It is another example of showing the 'fluorescence structural self-quenching effect' as we reported previously, from which it is demonstrated again that this phenomenon is not an accidental one but a common effect for acrylic monomers bearing electon-donating chromophores. The photopolymerization of AN sensitized by MAPOA and P(MAPOA) was studied. The kinetic equation of the polymerization was obtained and represented as follows: R _p∝ 0.38 × 0.78 , R _p∝ 0.33 × 0.71 The overall activation energies were determined to be E_ a =24\^22 kJ/mol(MAPOA) and E_ a =26\^31 kJ/mol respectively. The fluorescence analysis of the resulted P(AN) showed that the sensitizer also entered into the P(AN) chains. A mechanism of the formation of a charge transfer complex and free radical initiation was suggested for the photopolymerization of AN sensitized by MAPOA and P(MAPOA).展开更多
The stress hardening characteristics of the reinforced rock mass in uniaxial compression tests were revealed by means of the experimental study on mechanical characteristics of cracked rock mass reinforced by bolting ...The stress hardening characteristics of the reinforced rock mass in uniaxial compression tests were revealed by means of the experimental study on mechanical characteristics of cracked rock mass reinforced by bolting and grouting. And the load-beating mechanism of the reinforced rock mass was perfectly reflected by the experiment. The results can offer some useful advice for support design and stability analysis of deep drifts in unstable strata.展开更多
基金supported by the Natural Science Foundation of China(grant No.71173174)
文摘Based on the survey data of typical villages in Shaanxi Province,China,the effect of social capital on the income gap of farmers' households was analyzed using the Shapley value of the total amount of social capital and the social capital structure.The results show the following:first,social capital can expand the household income gap,and the effect of this index on the household income gap is 7.54%.Second,the indexes of the social capital dimension can expand the household income gap,and the structural effects of the household income gap on social networks,social trust,and social participation are 3.17%,3.64%,and 0.65%,respectively.Third,no dimension of the path is the same as the effect on the household income gap.
基金Financial supports for this work, provided by the New Century Excellent Talents in University (No.NCET-05-0480)the Research Fund of the State Key Laboratory of Coal Resources and Mine Safety of CUMT (No.09KF06)the Scientific Research Fund of CUMT (No.OA090239)
文摘The stability of a backfill wall is critical to implement gob-side entry driving technology in which a small coal pillar is substituted by a waste backfill wall. Based on features of surrounding rock structures in the backfill wall, we propose a mechanical model on the structural effect of a soft-hard backfill wall using theory analysis, physical experiments and a numerical simulation. The results show thatChe deformation of the structure of the soft-hard backfill wall is coordinated with the roof and floor. The soft structure on the top of the backfill wall can absorb the energy in the roof by its large deformation and adapt to the given deformation caused by the rotation and subsidence of a key rock block. The hard structure at the bottom of the backfill wall can absorb the strong supporting resistance from the top surrounding rock. The soft structure on the top protecting the hard bottom structure by its large deformation contributes to the stability of the entire backfill wall. An application indicated that the stress in the backfill wall effec- tively decreased and its deformation was significantly reduced after the top coal remained. This ensured the stability of the backfill wall.
文摘Through improvements on a fully commercial and automatic system measuring frequency andtemperature spectra of the complex elastic, dielectric, and piezoelectric constants of polymerfilms, the precision for measuring complex dielectric constants achieved 2‰ from original 1%.The complex dielectric constants of PVDF, VDF （95 ）/VF （5）, VDF （52）/TrFE （48） and VDF（47. 5）/TrFE（47. 5）/HeFP （5） over a range of-120-140℃, 10-2-10;Hz were measured bythe described system. The diminution of chain regularity due to 5mol% vinyl fluoride in the chainof PVDF led to disappearing of α-relaxation and increase in T;（3℃） of VDF （95）/VF （5）.Because of the spatial impediment of 5mol% HeFP in copolymer chain, the Curie point of VDF（52）/TrFE（48） decreased by 30℃ and T;by 3℃. The behavior of dielectric relaxation indicatedthat 5mol% vinyl fluoride and HeFP made the relaxation strength of noncrystalline regionreduced, the activation energy of local relaxation increased and the relaxation time prolonged respectively.
文摘The struetural effect of the conjugative system(C)with carbonyl-imino bridges has been studied.The results show that:In the conjugated system(C),there is no electronic absorption peak attributable to the whole system,but there are three π-π* bands each nt which displays chacactecistics of its own independently.These indicate that the two bridges-carbonyl-and-imino-can block the tlanSmlSSion of the conjngative polarization of the whole system,so as to form three segments,this is verified by means of chemical synthesis and degradation.
基金Supported by the Department of Physics,the University of AJKHigh Tech.Centralized Instrumentation Lab,the University of AJK,Pakistanthe Experimental Physics Division,and the National Center for Physics,Islamabad Pakistan
文摘The 0.8 Me V copper ( Cu) ion beam irradiation-induced effects on structural, morphological and optical properties of tin dioxide nanowires (SnO_(2)NWs) are investigated. The samples are irradiated at three different doses 5 × 10^12 ions/cm^(2), 1 ×10^(13) ions/cm^(2) and 5 × 10^(13) ions/em^(2) at room temperature. The XRD analysis shows that the tetragonal phase of SnO_(2)NWs remains stable after Cu ion irradiation, but with increasing irradiation dose level the crystal size increases due to ion beam induced coalescence of NWs. The FTIR spectra of pristine SnO_(2)NWs exhibit the chemical composition of SnO_(2)while the Cn-O bond is also observed in the FTIR spectra after Cu ion beam irradiation. The presence of Cu impurity in SnO_(2)is further confirmed by calculating the stopping range of Cu ions by using TRM/SRIM code. Optical properties of SnO_(2)NWs are studied before and after Cu ion irradiation. Band gap analysis reveMs that the band gap of irradiated samples is found to decrease compared with the pristine sample. Therefore, ion beam irradiation is a promising technology for nanoengineering and band gap tailoring.
文摘The characteristics and distribution of faults in Yinggehai basin discussed in this paper reveal the structural effects of the overpressure fluid expulsion. The rapid subsidence and mud rich intervals of the marine rocks dominate the formation of the overpressure systems and the enormous volumes of the overpressure fluids in the basin. Triggered by some faults, the overpressure fluids were expulsed rapidly from the overpressure compartments to form a series of diapirs in the basin, resulting in the dense fractures or faults and folds in the limbs of diapirs. These fractures and faults provided the migration pathway for the vertical flow of hydrocarbons, so that the gas fields arising from this process might migrate upwards to the sandstone reservoir. Therefore, the hydrocarbon accumulations are usually located in the upper parts of diapiric structures.
基金Supported by the National Basic Research Program of China under Grant Nos 2011CB921904 and 2012CB927402the National Natural Science Foundation of China under Grant Nos 11074142 and 11021464+1 种基金the Key Project of Chinese Ministry of Education under Grant No 309003the Tsinghua TNList Cross-discipline Foundation
文摘Structural and magnetic properties are investigated for Fe1-xMnxV2O4 （0≤ x ≤ 1） spinels. As orbital-active Fe^2＋ is substituted with Mn^2＋, the cubie-to-tetragonM transition TsI and the tetragonal-to-orthorhombic transition Ts2 gradually decrease. These structural transitions originate from the Fe^2＋ ferro-orbital order （F-OO）. Below Yafet-Kittel （YK） magnetic transition TN2, V^3＋ orbital order （V-OO） plays an important role on global structure. Here x = 0.6 is a critical point. Fe^2＋ F-OO and V^3＋ F-OO coexist for 0 ≤ x ≤ 0.5. For x≥ 0.6, the orbital pattern of V^3＋ is antiferro （AF）-00, and Fe^2＋ F-OO disappears. Structural transition Ts3, accompanied by YK magnetic transition TN2, decreases initially, and then increases at x = 0.6. A scenario for the complex phase diagram arising from the cooperation or competition of Fe^2＋ and V^3＋ orbitals is proposed.
基金given by the University Grants Commission of India through the Major Research Project [UGC-MRP: F. No. 41-937/2012(SR)]
文摘Undoped and Zn-doped Cu2O films were deposited onto glass substrates using successive ionic layer adsorption and reaction（SILAR） technique with different Zn doping levels（0, 1, 2, 3, 5 and 10 wt%）. The structural,optical, and surface morphological studies were carried out and reported. The structural study revealed that the crystalline quality is gradually enhanced up to 5 wt% of Zn doping level, and then quality begins to degrade for further increase in doping level. Moreover, the preferential orientation changes from（111） to（110） for the highest doping level were examined. Optical study shows that the transmittance（65%） and optical band gap values are maximum（2.41 e V） when the Zn doping level is at 5 wt%. The photoluminescence study confirms the presence of various defects in the Cu2O matrix and also the variation obtained in the optical band gap from the transmittance data. SEM images revealed the annealinginduced changes in the surface morphology of the films.
基金supported by the National Key R&D Program of China(Grant No.2022YFF1303102)the Global Engagement for Strategic Partnership project of Nanjing University,the China Scholarship Council(Grant No.202406190182)+1 种基金the Swedish Research Council(VR,Grant No.2022–04672)the Kunshan Water Bureau for supporting this study through the project cooperation.
文摘Over the period of rainfall, urban green infrastructures(UGI) function like a sponge by absorbing surface runoff as sinks;however, they will shift to sources once their runoff reduction capacities are exceeded. This dynamic of sink-source shifts, and its dependence on the vegetation structure, remain poorly understood, limiting the action of flood-resilient UGI strategies. This study employs MIKE SHE/11 model coupled with statistical analysis for such resolution. Across four scenarios ranging from light to heavy rainfall, we identified regime shifts in UGI system through the decreasing to increasing trends of sink fractions, typically occurring around 13–18 h after rainfall starts. Based on these regime shifts, we categorized the UGI system into vulnerable, reliable, and recoverable components, highlighting its heterogeneous performance. In addition, by examining the influence of vegetation structure on sink–source dynamics, we found that a higher probability of sinks under light rainfalls was associated with a greater leaf area index(LAI) and vegetation height standard deviation(VHSTD), while green volume(GV) and canopy height(CH) played a more prominent role under heavier rainfalls. Threshold effect analysis further revealed that, a high proportion of the recoverable parts met the thresholds of CH(82 %)and GV(85 %), whereas fewer reached the thresholds of LAI(15 %–19 %) and VHSTD(3 %–6 %). These findings underscore the importance of enhancing 3D vegetation configuration for UGI to adapt to flood impacts. Our study expects to provide actionable knowledge for understanding, quantification, and management of the runoff sink-source dynamics, informing UGI design and planning to achieve urban flood resilience.
基金supported by the National Natural Science Foundation of China(Grant No.12402445)the National Defense Foundation Stabilization Support Program(Grant No.JCKYS2024212108)the National Key Laboratory of Shock Wave Physics and Detonation Physics Foundation(Grant No.2024CXPTGFJJ06404)。
文摘Accurate characterization of three-dimensional burning crack propagation remains pivotal yet challenging for energetic material safety,as conventional diagnostics and models inadequately resolve coupled crack-pressure dynamics in confined explosives.This study combines a novel spherical confinement system(with/without sapphire windows)with synchronized high-speed imaging and 3D reconstruction to overcome optical limitations in opaque explosives.Experimental analysis of centrally ignited HMX-based PBX-1 reveals:(1)burning cracks propagate radially with equatorial acceleration and polar deceleration,(2)systematic formation of 3–4 dominant crack branches across geometries,and(3)pressure evolution exhibiting gradual accumulation(subsurface cracking)followed by exponential growth(surface burn-through),with decay governed by cavity expansion.Building on Hill's framework,we develop a model incorporating cavity volume and fracture toughness criteria,validated against PBX explosive(95%HMX-based)experiments.The model demonstrates improved prediction of pressure trends compared to prior approaches,particularly in resolving laminar-phase accumulation and crackinduced surge transitions.Results establish structural cavity volume as a critical modulator of measured pressure and reveal direction-dependent crack kinematics as fundamental features of constrained combustion.This work provides experimentally validated insights into mechanisms of reaction pressure development and burning cracks pathways during constrained PBX explosive combustion.
基金financially supported by the Joint Fund of Coal, set up by National Natural Science Foundation of China and Shenhua Co., Ltd.(U1261104)the National Natural Science Foundation of China (21276041)+3 种基金the Program for New Century Excellent Talents in University (NCET-12-0079)the Natural Science Foundation of Liaoning Province (2015020200)the Fundamental Research Funds for the Central Universities (DUT15LK41)the Science and Technology Development Program of Hangzhou (20130533B14)~~
文摘An immature pinecone shaped hierarchically structured zirconia （ZrO2-ipch） and a cobblestone-like zirconia nanoparticulate （ZrO2-cs）, both with the monoclinic phase （m-phase）, were synthesized by the facile hydrothermal method and used as the support for a Ni catalyst for the dry reforming of methane （DRM） with CO2. ZrO2-ipch is a much better support than ZrO2-cs and the traditional ZrO2 irregular particles made by a simple precipitation method （ZrO2-ip）. The supported Ni catalyst on ZrO2-ipch （Ni/ZrO2-ipch） exhibited outstanding catalytic activity and coke-resistant stability compared to the ones on ZrO2-cs （Ni/ZrO2-cs） and ZrO2-ip （Ni/ZrO2-ip）. Ni/ZrO2-ip exhibited the worst catalytic performance. The origin of the significantly enhanced catalytic performance was revealed by characterization including XRD, N2 adsorption measurement （BET）, TEM, H2-TPR, CO chemisorption, CO2-TPD, XPS and TGA. The superior catalytic activity of Ni/ZrO2-ipch to Ni/ZrO2-cs or Ni/ZrO2-ip was ascribed to a higher Ni dispersion, increased reducibility, enhanced oxygen mo- bility, and more basic sites with a higher strength, which were due to the unique hierarchically structural morphology of the ZrO2-ipch support. Ni/ZrO2-ipch exhibited better stability for the DRM reaction than Ni/ZrO2-ip, which was ascribed to its higher resistance to Ni sintering due to a strengthened metal-support interaction and the confinement effect of the mesopores and coke deposition resistance. The higher coking resistance of Ni/ZrO2-ipch for the DRM reaction in comparison with Ni/ZrOz-ip orignated from the coke-removalabitity of the higher amount of lattice oxygen and more basic sites, confirmed by XPS and CO2-TPD analysis, and the stabilized Ni on the Ni/ZrO2-ipch catalyst by the confinement effect of the mesopores of the hierarchical ZrO2-ipch sup- port. The superior catalytic performance and coking resistance of the Ni/ZrO2-ipch catalyst makes it a promising candidate for synthesis gas production from the DRM reaction.
文摘Several MoS2 catalysts of different structure, prepared by in situ decomposition of ammonium heptamolybdate （AHM） and molybdenum naphthenate （MoNaph）, and by MoS2 exfoliation （TDM）, were characterized by BET, X-ray diffraction （XRD）, Energy Dispersive X-ray （EDX） and transmission electron microscopy （TEM）. The analysis showed that MoS2 structure was dependant upon the preparation procedure. The activity of the catalysts was determined by measuring the hydrodeoxygenation （HDO） of phenol, 4-methylphenol and 4-methoxyphenol using a batch autoclave reactor operated at 2.8 MPa of hydrogen and temperatures ranging from 320-370℃. By comparing the conversion, the reactivity order of the catalysts was： AHM〉TDM-D〉MoNaph〉thermal〉MoS2 powder〉 TDM-W. Also, the effect of reaction temperature on the HDO conversion was explained in terms of equilibrium of reversible reaction kinetics. The main products of the HDO for phenolic compounds were identified by gas chromatography/mass spectrometry （GC/MS）. The results showed that the product distribution and the HDO selectivity were correlated with the reaction temperature. Two parallel reaction routes, direct hydrogenolysis and combined hydrogenation-hydrogenolysis, were confirmed by the analysis of the product distribution. High temperature favored hydrogenolysis over hydrogenation for HDO of phenol and 4-methoxyphenol, whereas for 4-methylphenol the reverse was true.
基金Under the auspices of Soft Science Project of Agricultural Department of China (No.0508)
文摘China＇s success in reform and opening up policy for twenty years is regarded as China＇s miracles in the world, whereas the income differential widening phenomenon has been the focus of the policymakers and researchers. This article researches 1994-2003 China＇s rural regions income differential and its decomposition. The method this paper used to measure the disparity is Gini Index. There are many ways to compute it, so the easiest way to decompose Gini Index-Matrix method is adopted. And based on it, farmer＇s income could be divided into wage income, fanning income, transfer income and property income according to its composition. The conclusion is that all of the indexes are between 0.2 and 0.3, at the comparatively average level. From the fluctuation trend, it increased from 1994 to 1995, while reduced from 1995 to 1996, fluctuated in 1997, and then diminished again. In general, farmer＇s regions income differential stays at comparatively average level, but it has the widening trend with time. Through decomposing Gini Index, wage income is the most important increasing factor, while fanning income is the reducing factor.
文摘Carbon dioxide emissions have increased due to the consumption of fossil fuels,making the neutralization and utilization of CO_(2) a pressing issue.As a clean and efficient energy conversion process,electrocatalytic reduction can reduce carbon dioxide into a series of alcohols and acidic organic molecules,which can effectively realize the utilization and transformation of carbon dioxide.This review focuses on the tuning strategies and structure effects of catalysts for the electrocatalytic CO_(2) reduction reaction(CO_(2)RR).The tuning strategies for the active sites of catalysts have been reviewed from intrinsic and external perspectives.The structure effects for the CO_(2)RR catalysts have also been discussed,such as tandem catalysis,synergistic effects and confinement catalysis.We expect that this review about tuning strategies and structure effects can provide guidance for designing highly efficient CO_(2)RR electrocatalysts.
基金the National Natural Science Foundation of China(No.21878116)Natural Science Foundation of Hubei Province(No.2019CFA070)。
文摘Hydrogenation of CO_(2) to value-added chemicals has attracted much attention all through the world.In2 O_(3) with cubic bixbyite-type(denoted as c-In2O_(3))is well known for its high CO_(2) hydrogenation activity and CH3 OH selectivity at high temperature.However,the other structure of In2O_(3) with rhombohedral corundum-type(denoted as rh-In2O_(3))rarely been investigated as catalyst.Herein,c-In2O_(3) and rh-In2O_(3) were prepared and comparatively studied for CO_(2) hydrogenation.The results indicated that c-In2O_(3) showed higher CO_(2) conversion activity than rh-In2O_(3) due to the impressive reducibility and reactivity.Whereas rh-In2O_(3) had higher CH3 OH selectivity due to weaker CH3 OH and stronger CO adsorption on rhIn2O_(3).Although c-In2O_(3) and rh-In2O_(3) catalysts showed different CO_(2) hydrogenation perfo rmance,in-situ diffuse reflectance infrared Fourier transform spectroscopy showed CO_(2) can be reduced to CO through redox cycling and hydrogenation to CH3 OH through formate path.
基金National Technology Research and Development Program of the Ministry of Science and Technology of China under Grant No.2015BAK17B03National Natural Science Foundation of China(General Program)under Grant No.51278152+1 种基金National Science & Technology Pillar Program(2015BAK17B06)Program for Innovation Research Team in China Earthquake Administration
文摘Due to the randomness of earthquake wave magnitude and direction, and the uncertain direction of strong axis and weak axis in the construction of engineering structures, the effect of the direction of ground motion on a structure are studied herein. Ground motion records usually contain three vertical ground motion data, which are obtained by sensors arranged in accordance with the EW （East -West） direction, NS （South- North） direction and perpendicular to the surface （z） direction, referring to the construction standard of seismic stations. The seismic records in the EW and NS directions are converted to Cartesian coordinates in accordance with the rotation of θ = 0°-180°, and consequently, a countless group of new ground motion time histories are obtained. Then, the characteristics of the ground motion time history and response spectrum of each group were studied, resulting in the following observations： （1） the peak and phase of ground motion are changed with the rotation of direction θ, so that the direction θ of the maximum peak ground motion can be determined; （2） response spectrum values of each group of ground motions change along with the direction θ, and their peak, predominant period and declining curve are also different as the changes occur; then, the angle θ in the direction of the maximum peak value or the widest predominant period can be determined; and （3） the seismic response of structures with different directions of ground motion inputs has been analyzed under the same earthquake record, and the results show the difference. For some ground motion records, such as the Taft seismic wave, these differences are significant. Next, the Lushan middle school gymnasium structure was analyzed and the calculation was checked using the proposed method, where the internal force of the upper space truss varied from 25% to 28%. The research results presented herein can be used for reference in choosing the ground motion when checking the actual damage to structures following earthquakes and explaining the seismic damage. Meanwhile, it also provides a reference value for research into the most severe ground motion.
文摘Foam structure materials are well known for their lightweight,efficient,and broadband microwave absorption properties compared to bulk material.However,little has been understood about the effect of a foam structure on the absorption performance of the foam material.In this study,the role of foam structure properties of the silicon carbide/carbon(SiC/C)foam material on microwave absorption is explored using experiment and simulation.We find that the foam structure of SiC/C foam material causes diffraction,multiple reflections,improves the interfacial polarization,and compatibilization.The absorption performance of SiC/C foam material is also studied.The-10 dB effective absorption bandwidth can be adjusted from 4.0 GHz to 18 GHz by tuning SiC/C foam material thickness to 3-7 mm.Therefore,the foam structure design is an effective way to improve the absorption performance of the SiC/C foam material.
基金financial support by NWO-VICI and NWO-TOP grants awarded to Emiel J.M.Hensen
文摘Fischer-Tropsch synthesis （FTS） is an increasingly important approach for producing liquid fuels and chemicals via syngas-that is, synthesis gas, a mixture of carbon monoxide and hydrogen-generated from coal, natural gas, or biomass. In FTS, dispersed transition metal nanoparticles are used to catalyze the reactions underlying the formation of carbon-carbon bonds. Catalytic activity and selectivity are strongly correlated with the electronic and geometric structure of the nanoparticles, which depend on the particle size, morphology, and crystallographic phase of the nanoparticles. In this article, we review recent works dealing with the aspects of bulk and surface sensitivity of the FTS reaction. Understanding the different catalytic behavior in more detail as a function of these parameters may guide the design of more active, selective, and stable FTS catalysts.
文摘A novel acrylic monomer bearing aromatic ethereality group N-(p -phenoxy-phenyl) methacrylamide(MAPOA) was synthesized and polymerized. The fluorescence spectra of MAPOA and its polymer were studied, showing that the polymer displays a stronger fluorescence than its monomer at the same chromophore concentration. The fluorescence of P(MAPOA) was quenched by adding electron deficiency monomers such as MMA, AN etc .. It is another example of showing the 'fluorescence structural self-quenching effect' as we reported previously, from which it is demonstrated again that this phenomenon is not an accidental one but a common effect for acrylic monomers bearing electon-donating chromophores. The photopolymerization of AN sensitized by MAPOA and P(MAPOA) was studied. The kinetic equation of the polymerization was obtained and represented as follows: R _p∝ 0.38 × 0.78 , R _p∝ 0.33 × 0.71 The overall activation energies were determined to be E_ a =24\^22 kJ/mol(MAPOA) and E_ a =26\^31 kJ/mol respectively. The fluorescence analysis of the resulted P(AN) showed that the sensitizer also entered into the P(AN) chains. A mechanism of the formation of a charge transfer complex and free radical initiation was suggested for the photopolymerization of AN sensitized by MAPOA and P(MAPOA).
基金Projects50490273 and 50474063 supported by National Natural Science Foundation of China
文摘The stress hardening characteristics of the reinforced rock mass in uniaxial compression tests were revealed by means of the experimental study on mechanical characteristics of cracked rock mass reinforced by bolting and grouting. And the load-beating mechanism of the reinforced rock mass was perfectly reflected by the experiment. The results can offer some useful advice for support design and stability analysis of deep drifts in unstable strata.
