With the modern development of chemical and mineral admixtures, it is now possible to produce much higher performance concrete than before. Higher performance does not only mean higher strength, but also better durabi...With the modern development of chemical and mineral admixtures, it is now possible to produce much higher performance concrete than before. Higher performance does not only mean higher strength, but also better durability, lower risk of thermal cracking and higher dimensional stability etc. The three most effective admixtures for producing high performance concrete are superplastieizer, pulverized fuel ash and condensed silica fume. This paper outlines the properties of these materials and presents some practical guidelines for their usage.展开更多
This paper studies the effect of different environmental factors, including the axle load weight, environmental temperature, vehicle speed, and the aging level of asphalt, on the fatigue performance of asphalt mixes b...This paper studies the effect of different environmental factors, including the axle load weight, environmental temperature, vehicle speed, and the aging level of asphalt, on the fatigue performance of asphalt mixes based on four-point bending beam fatigue tests. A fractional factorial design method named ＂uniform design＂ was applied in experimental design. The relations of the environmental factors to initial stiffness, fatigue life, phase angle and cumulative dissipated energy were established with the general linear modeling method. It is found that there exists very good correlativity between the environmental factors and the fatigue performance indices of asphalt mixes. The coefficients of total correlation are mainly beyond 0. 95. The results indicate that the consideration of the effect of environmental factors is necessary in the fatigue performance evaluation on real asphalt pavement.展开更多
Aluminium powders were introduced to Al2O3-SiC-C dry ramming mixes in order to improve sintering properties and oxidation resistance according to their service conditions and installation methods. Properties such as b...Aluminium powders were introduced to Al2O3-SiC-C dry ramming mixes in order to improve sintering properties and oxidation resistance according to their service conditions and installation methods. Properties such as bulk density, porosity, modulus of rupture, crushing strength and hot modulus of rupture as a function of aluminium addition were investigated in the present work. The microstructure and thermodynamics for the heat treated specimens were also analyzed. The results show that as aluminium addition increasing, the bulk density of the specimen treated at 220℃ tends to decrease and the apparent porosity increases, the strength of the specimens treated at 1100℃ and 1450℃ increases markedly, the bulk density tends to increase, apparent porosity and linear shrinkage decrease. The HMOR at 1400℃ is enhanced from 1.0 MPa to 3.5 MPa with 3% aluminium. Aluminium is served as sintering agent and anti-oxidant and it will react with CO and CO2 forming Al2O3 , which is helpful to enhance the strength, densify the structure and improve the overall properties.展开更多
Nano silica due to its spherical shape, tiny size and higher density compared to bitumen, may have an inherent potential to improve hot mix asphalt(HMA) self-healing. In this research scanning electron microscopy(SEM)...Nano silica due to its spherical shape, tiny size and higher density compared to bitumen, may have an inherent potential to improve hot mix asphalt(HMA) self-healing. In this research scanning electron microscopy(SEM) images were used to investigate size, morphology and dispersion of nano silica particles. Additionally, HMA self-healing mechanism was also examined by SEM. Furthermore, dynamic indirect tensile test(IDT) was used to evaluate HMA self-healing index. The SEM results indicated that bitumen mortar flowing into micro cracks may be one of the most important mechanisms of HMA self-healing. The experiment results also showed that modification of bitumen by nano silica promotes the ability of the HMA self-healing.展开更多
Mg0-Al2O3-Cr2O3 ramming mixes made of different raw materials have different mineral structure and different physical properties though with the identical particle size distribution, the same amount of binder and chem...Mg0-Al2O3-Cr2O3 ramming mixes made of different raw materials have different mineral structure and different physical properties though with the identical particle size distribution, the same amount of binder and chemical composition . The residual carbon content of the fused magnesia-chrome material made in reducing atmosphere is very high, if this material is used in the MgO-Al203-Cr2O3 ramming mix , it would cause spalling of the furnace lining during drying-out.展开更多
Magnesia-alumina-chrome ramming mixes with same chemical compositions were prepared by using different raw materials such as fused magnesia-chrome synthetic materials and sintered one, wasted bricks and magnesia-alumi...Magnesia-alumina-chrome ramming mixes with same chemical compositions were prepared by using different raw materials such as fused magnesia-chrome synthetic materials and sintered one, wasted bricks and magnesia-alumina spinels. Their physical properties were tested and microstructures were analyzed. The results show that the ramming mixes made of different raw materials bring about different microstructures and properties although the mixes have the same chemical composition, binder content and aggregate size composition.展开更多
Al_(2)O_(3)-SiO_(2) based gunning mixes were prepared with electric porcelain waste,silica fume,bauxite,quartz powder,and calcium aluminate cement(CAC)of different additions as raw materials firing at different temper...Al_(2)O_(3)-SiO_(2) based gunning mixes were prepared with electric porcelain waste,silica fume,bauxite,quartz powder,and calcium aluminate cement(CAC)of different additions as raw materials firing at different temperatures to research the effect of the CAC addition on their phase change and properties.The results show that:from theoretical analysis of the phase diagram,with the CAC addition increasing from 8%to 14%,anorthite increases from 40.0%to 77.7%,by mass.With the rising CAC addition,the permanent linear change on heating of specimens increases;for the specimens dried at 110℃or hot-treated at 1000℃,the bulk density and the mechanical properties increase,and the apparent porosity decreases;and for those hottreated at 1300℃,the bulk density and the mechanical properties firstly increase,and then decrease,while the apparent porosity shows an opposite trend.Taking into account the phases at high temperatures and the properties,the optimal CAC addition of Al_(2)O_(3)-SiO_(2) based gunning mixes is 12%.展开更多
Current pavement design methods do not allow for the reduction of early deformation of the surface layers of bituminous pavements in the city of Ouagadougou. Weather conditions combined with traffic, particularly duri...Current pavement design methods do not allow for the reduction of early deformation of the surface layers of bituminous pavements in the city of Ouagadougou. Weather conditions combined with traffic, particularly during heat waves, are factors. The temperature at the surface of the bituminous pavement can reach 62˚C but the complex modulus associated with this temperature is not taken into account in the design, hence the interest in proposing laws of dependence of the complex moduli is taken into account in the maximum temperatures of the pavement surface. The objective of this paper is to propose an experimental method to determine the temperature dependence of the complex moduli of asphalt mixes for temperatures between 40˚C and 70˚C. This experimental method consists of performing axial compression tests on cylindrical asphalt specimens. It was applied to three different formulas of bituminous mixes, intended for the wearing course, obtained from mixes of crushed granites, granular classes 6/10, 4/6 and 0/4, pure bitumens of grade 50/70, 35/50 and modified bitumen of grade 10/65. The comparative study of the experimental results obtained with the results of a semi-empirical methodology revealed a root mean square deviation from the mean of between 6.58% and 14.8% of the norms of the complex moduli (modulus of rigidity) of the asphalt mixes for a fixed frequency of solicitations of 10 Hz. The consistency of these results with data from the literature led to the initial conclusion that asphalt mixes formulated with 35/50 and 10/65 bitumen would have better compressive strength than those formulated with 50/70 bitumen, for exposure temperatures between 40˚C and 70˚C. This experimental approach could be an alternative to the complex modulus test for determining the modulus of rigidity for design purposes under real pavement exposure conditions in the city of Ouagadougou during heat waves.展开更多
Evaluating the functional boundary of different types of innovation policy instruments and their mixes on innovation performance of enterprises is an important but unresolved key issue.This paper,based on the systemat...Evaluating the functional boundary of different types of innovation policy instruments and their mixes on innovation performance of enterprises is an important but unresolved key issue.This paper,based on the systematically carding the quantization of 155 innovation policies issued by Shenzhen governmental departments from 2011 to 2019,analyzed the characteristics from different types of innovation instruments and their mixes.The results show that Shenzhen governmental has constantly enriched innovation policy instruments for encouraging enterprise innovation,but there are structural unbalances in the issued innovation policy manifested as follows:firstly supply-side policy and environmental-side policy were promulgated more than demand-side policy;secondly the specific instruments employed by Shenzhen governmental were also uneven in different type of innovation policy,like supply-side policy focused on the instruments of government procurement and R&D outsourcing,demand-side policy employed human resource training,innovation infrastructure and fiscal support most,and environmental-side policy main used target planning,intellectual property protection and financial support.This study expands and understanding empirical implementation of different reginal innovation policy instruments,and has implication for Shenzhen governmental in improving the applicability ability of policies in the enterprises innovation.展开更多
Properties of aggregates are majorly influenced by parameters of source rocks viz.,formation process,chemical composition,impurities,volume of pores,and grain size.The study presents a review of aggregate treatment me...Properties of aggregates are majorly influenced by parameters of source rocks viz.,formation process,chemical composition,impurities,volume of pores,and grain size.The study presents a review of aggregate treatment methods and its efficacy to enhance the quality of aggregate.Various aspects of aggregate treatment methods like processing temperature,the dosage of additives,adaptability in the field is studied for three treatment methods viz.,polymer coating,cementitious coating,and chemical treatments.The paper also presents an insight to understand the effect of different treatment methods on mix properties and performance parameters of asphalt mixes.The review revealed that the shape properties of aggregates can be enhanced by the incorporating suitable crushing process(two-stage or three-stage).Whereas,physical and durability properties of aggregates can be improved by various treatment methods like polymer coating,Zycosoil treatment.It was further inferred from the review that treatment methods can have moderate effects on the mechanical properties of aggregates,since,it is mostly dependent on properties of source rocks.展开更多
This paper deals with Raviart-Thomas element (Q(2,1) x Q(1,2) - Q(1) element). Apart from its global superconvergence property of fourth order, we prove that a postprocessed extrapolation can globally increased the ac...This paper deals with Raviart-Thomas element (Q(2,1) x Q(1,2) - Q(1) element). Apart from its global superconvergence property of fourth order, we prove that a postprocessed extrapolation can globally increased the accuracy by fifth order.展开更多
Direct seawater splitting has emerged as a popular and promising research direction for synthesising clean,green,non-polluting,and sustainable hydrogen energy without depending on high-purity water in the face of the ...Direct seawater splitting has emerged as a popular and promising research direction for synthesising clean,green,non-polluting,and sustainable hydrogen energy without depending on high-purity water in the face of the world’s shortage of fossil energy.However,efficient seawater splitting is hindered by slow kinetics caused by the ultra-low conductivity and the presence of bacteria,microorganisms,and stray ions in seawater.Additionally,producing hydrogen on an industrial scale is challenging due to the high production cost.The present review addresses these challenges from the catalyst point of view,namely,that designing catalysts with high catalytic activity and stability can directly affect the rate and effect of seawater splitting.From the ion transfer perspective,designing membranes can block harmful ions,improving the stability of seawater splitting.From the energy point of view,mixed seawater systems and self-powered systems also provide new and low-energy research systems for seawater splitting.Finally,ideas and directions for further research on direct seawater splitting in the future are pointed out,with the aim of achieving low-cost and high-efficiency hydrogen production.展开更多
Paste and mortar specimens were prepared with sulfoaluminate cement(SAC),P⋅O 42.5 ordinary Portland cement(OPC),and standard sand,and mixed and cured with pure water and artificial seawater,respectively.The mechanical...Paste and mortar specimens were prepared with sulfoaluminate cement(SAC),P⋅O 42.5 ordinary Portland cement(OPC),and standard sand,and mixed and cured with pure water and artificial seawater,respectively.The mechanical properties of mortar specimens were tested.Hydration and microstructure of paste specimens were also investigated using X-ray diffraction(XRD),scanning electron microscope(SEM),and 27Al nuclear magnetic resonance(NMR),respectively.The results indicate that SAC mortar samples mixed and cured by seawater have faster strength growth before 28 d and higher compressive strength than OPC mortar samples.Compared to curing in deionized water,the hydration products of SAC are somewhat coarser when cured in simulated seawater.The evolution of aluminum phase hydration products during the hydration process of SAC mixed and cured in simulated seawater is quite different from that of OPC.From 3 to 28 d,the content of each aluminum phase hydration product in SAC paste cured in simulated seawater changed little,while that in OPC paste changed significantly;for example,from 7 to 28 d,the content of ettringite(AFt)in OPC paste increased significantly.This type of AFt formed loosely,harming the mortar's microstructure.展开更多
Mixed matrix membranes(MMMs)have demonstrated significant promise in energy-intensive gas separations by amalgamating the unique properties of fillers with the facile processability of polymers.However,achieving a sim...Mixed matrix membranes(MMMs)have demonstrated significant promise in energy-intensive gas separations by amalgamating the unique properties of fillers with the facile processability of polymers.However,achieving a simultaneous enhancement of permeability and selectivity remains a formidable challenge,due to the difficulty of achieving an optimal match between polymers and fillers.In this study,we incorporate a porous carbon-based zinc oxide composite(C@ZnO)into high-permeability polymers of intrinsic microporosity(PIMs)to fabricate MMMs.The dipole–dipole interaction between C@ZnO and PIMs ensures their exceptional compatibility,mitigating the formation of non-selective voids in the resulting MMMs.Concurrently,C@ZnO with abundant interconnected pores can provide additional low-resistance pathways for gas transport in MMMs.As a result,the CO_(2) permeability of the optimized C@ZnO/PIM-1 MMMs is elevated to 13,215 barrer,while the CO_(2)/N_(2) and CO_(2)/CH_(4) selectivity reached 21.5 and 14.4,respectively,substantially surpassing the 2008 Robeson upper bound.Additionally,molecular simulation results further corroborate that the augmented membrane gas selectivity is attributed to the superior CO_(2) affinity of C@ZnO.In summary,we believe that this work not only expands the application of MMMs for gas separation but also heralds a paradigm shift in the application of porous carbon materials.展开更多
An aluminoborate,Na_(2.5)Rb[Al{B_(5)O_(10)}{B_(3)O_(5)}]·0.5NO_(3)·H_(2)O(1),was synthesized under hydrothermal condition,which was built by mixed oxoboron clusters and AlO_(4)tetrahedra.In the structure,the...An aluminoborate,Na_(2.5)Rb[Al{B_(5)O_(10)}{B_(3)O_(5)}]·0.5NO_(3)·H_(2)O(1),was synthesized under hydrothermal condition,which was built by mixed oxoboron clusters and AlO_(4)tetrahedra.In the structure,the[B_(5)O_(10)]^(5-)and[B_(3)O_(7)]^(5-)clusters are alternately connected to form 1D[B_(8)O_(15)]_(n)^(6n-)chains,which are further linked by AlO_(4)units to form a 2D monolayer with 7‑membered ring and 10‑membered ring windows.Two adjacent monolayers with opposite orientations further form a porous‑layered structure with six channels through B—O—Al bonds.Compound 1 was characterized by single crystal X‑ray diffraction,powder X‑ray diffraction(PXRD),IR spectroscopy,UV‑Vis diffuse reflection spectroscopy,and thermogravimetric analysis(TGA),respectively.UV‑Vis diffuse reflectance analysis indicates that compound 1 shows a wide transparency range with a short cutoff edge of 201 nm,suggesting it may have potential application in UV regions.CCDC:2383923.展开更多
Hybrid nanofluids are known for their attractive thermophysical properties and enhanced heat transfer potential.This study thoroughly investigates the impact of particle mixing ratios on the thermophysical and heat tr...Hybrid nanofluids are known for their attractive thermophysical properties and enhanced heat transfer potential.This study thoroughly investigates the impact of particle mixing ratios on the thermophysical and heat transfer characteristics of MgO-SiO_(2)/water hybrid nanofluid.The mixing mass ratio(MR)of MgO:SiO_(2)was systematically altered including ratios of 100:0,80:20,60:40,50:50,40:60,20:80,and 0:100 at a fixed particle concentration of 0.01%in volume.Experimental assessments of thermal conductivity and viscosity were conducted within the temperature range of 25℃-50℃at 5℃intervals.Thermal conductivity was measured by analysing sonic velocity of sound in nanofluid medium.Viscosity was determined by Ostwald viscosity apparatus.Sensitivity analysis was performed to examine the influence of mixing ratio and temperature on thermal conductivity and viscosity.Sustainability and economic analysis were conducted to guide future applications.The findings highlight the substantial influence of MR on thermal conductivity and viscosity enhancements within the hybrid nanofluid.The thermal conductivity exhibited a positive correlation with temperature elevation,with the hybrid nanofluid at MR=60:40 and 50℃displaying the highest thermal conductivity enhancement at 20.84%compared to water.In contrast,viscosity decreased with increasing temperature,with MR=50:50 at 50℃showing the maximum viscosity increase at 5.06%compared to water.New data-driven correlations for precise predictions of thermal conductivity and viscosity of hybrid nanofluid have been proposed.Sensitivity analysis revealed that mixing ratio had a more pronounced impact than temperature elevation.Sustainability and economic analysis concludes that MR=60:40 is an optimal,economical and sustainable choice for achieving peak heat transfer performance.展开更多
In the Arctic Ocean,turbulent mixing drives vertical heat flux,thereby affecting the sea ice variability.Internal wave is regarded as one of the important energy sources of mixing in this region.The high latitude and ...In the Arctic Ocean,turbulent mixing drives vertical heat flux,thereby affecting the sea ice variability.Internal wave is regarded as one of the important energy sources of mixing in this region.The high latitude and sea ice cover make internal wave in the Arctic Ocean apparently differs from that in mid-and low-latitude oceans.However,the internal wave and its underlying mechanism are less understood due to the lack of observations.This paper briefly reviews the recent studies and unresolved questions on the internal wave in the Arctic Ocean,including wind-driven near-inertial wave,internal tide,and high-frequency internal wave.The aim is to provide new insights for in-depth research in the future,with a focus on the mechanisms responsible for the evolution of internal wave under the rapidly changing Arctic climate.展开更多
This work focuses on a Keller-Segel chemotaxis model, with an emphasis on its conservation laws. Through a new approach combined with the multiplier method, called the mixed method, we obtain conservation vectors that...This work focuses on a Keller-Segel chemotaxis model, with an emphasis on its conservation laws. Through a new approach combined with the multiplier method, called the mixed method, we obtain conservation vectors that are related and unrelated to symmetric information. In addition, some exact solutions with particular forms are obtained according to the method of conservation laws. These particular solutions are different from the group-invariant solutions.展开更多
DNA microarray technology is an extremely effective technique for studying gene expression patterns in cells, and the main challenge currently faced by this technology is how to analyze the large amount of gene expres...DNA microarray technology is an extremely effective technique for studying gene expression patterns in cells, and the main challenge currently faced by this technology is how to analyze the large amount of gene expression data generated. To address this, this paper employs a mixed-effects model to analyze gene expression data. In terms of data selection, 1176 genes from the white mouse gene expression dataset under two experimental conditions were chosen, setting up two conditions: pneumococcal infection and no infection, and constructing a mixed-effects model. After preprocessing the gene chip information, the data were imported into the model, preliminary results were calculated, and permutation tests were performed to biologically validate the preliminary results using GSEA. The final dataset consists of 20 groups of gene expression data from pneumococcal infection, which categorizes functionally related genes based on the similarity of their expression profiles, facilitating the study of genes with unknown functions.展开更多
This study elucidates the findings of a computational investigation into the stimulation characteristics of natural reservoir systems enhanced by high-voltage electropulse-assisted fluid injection.The presented method...This study elucidates the findings of a computational investigation into the stimulation characteristics of natural reservoir systems enhanced by high-voltage electropulse-assisted fluid injection.The presented methodology delineates the comprehensive rock-fracturing process induced by electropulse and subsequent fluid injection,encompassing the discharge circuit,plasma channel formation,shockwave propagation,and hydro-mechanical response.A hydromechanical model incorporating an anisotropic plastic damage constitutive law,discrete fracture networks,and heterogeneous distribution is developed to represent the natural reservoir system.The results demonstrate that high-voltage electropulse effectively generates intricate fracture networks,significantly enhances the hydraulic properties of reservoir systems,and mitigates the adverse impact of ground stress on fracturing.The stimulationenhancing effect of electropulse is observed to intensify with increasing discharge voltage,with enhancements of 118.0%,139.5%,and 169.0%corresponding to discharge voltages of 20 kV,40 kV,and 60 kV,respectively.Additionally,a high-voltage electropulse with an initial voltage of U_(0)=80 kV and capacitance C=5μF has been shown to augment the efficiency of injection activation to approximately 201.1%compared to scenarios without electropulse.Under the influence of high-voltage electropulse,the fluid pressure distribution diverges from the conventional single direction of maximum stress,extending over larger areas.These innovative methods and findings hold potential implications for optimizing reservoir stimulation in geo-energy engineering.展开更多
文摘With the modern development of chemical and mineral admixtures, it is now possible to produce much higher performance concrete than before. Higher performance does not only mean higher strength, but also better durability, lower risk of thermal cracking and higher dimensional stability etc. The three most effective admixtures for producing high performance concrete are superplastieizer, pulverized fuel ash and condensed silica fume. This paper outlines the properties of these materials and presents some practical guidelines for their usage.
文摘This paper studies the effect of different environmental factors, including the axle load weight, environmental temperature, vehicle speed, and the aging level of asphalt, on the fatigue performance of asphalt mixes based on four-point bending beam fatigue tests. A fractional factorial design method named ＂uniform design＂ was applied in experimental design. The relations of the environmental factors to initial stiffness, fatigue life, phase angle and cumulative dissipated energy were established with the general linear modeling method. It is found that there exists very good correlativity between the environmental factors and the fatigue performance indices of asphalt mixes. The coefficients of total correlation are mainly beyond 0. 95. The results indicate that the consideration of the effect of environmental factors is necessary in the fatigue performance evaluation on real asphalt pavement.
文摘Aluminium powders were introduced to Al2O3-SiC-C dry ramming mixes in order to improve sintering properties and oxidation resistance according to their service conditions and installation methods. Properties such as bulk density, porosity, modulus of rupture, crushing strength and hot modulus of rupture as a function of aluminium addition were investigated in the present work. The microstructure and thermodynamics for the heat treated specimens were also analyzed. The results show that as aluminium addition increasing, the bulk density of the specimen treated at 220℃ tends to decrease and the apparent porosity increases, the strength of the specimens treated at 1100℃ and 1450℃ increases markedly, the bulk density tends to increase, apparent porosity and linear shrinkage decrease. The HMOR at 1400℃ is enhanced from 1.0 MPa to 3.5 MPa with 3% aluminium. Aluminium is served as sintering agent and anti-oxidant and it will react with CO and CO2 forming Al2O3 , which is helpful to enhance the strength, densify the structure and improve the overall properties.
文摘Nano silica due to its spherical shape, tiny size and higher density compared to bitumen, may have an inherent potential to improve hot mix asphalt(HMA) self-healing. In this research scanning electron microscopy(SEM) images were used to investigate size, morphology and dispersion of nano silica particles. Additionally, HMA self-healing mechanism was also examined by SEM. Furthermore, dynamic indirect tensile test(IDT) was used to evaluate HMA self-healing index. The SEM results indicated that bitumen mortar flowing into micro cracks may be one of the most important mechanisms of HMA self-healing. The experiment results also showed that modification of bitumen by nano silica promotes the ability of the HMA self-healing.
文摘Mg0-Al2O3-Cr2O3 ramming mixes made of different raw materials have different mineral structure and different physical properties though with the identical particle size distribution, the same amount of binder and chemical composition . The residual carbon content of the fused magnesia-chrome material made in reducing atmosphere is very high, if this material is used in the MgO-Al203-Cr2O3 ramming mix , it would cause spalling of the furnace lining during drying-out.
文摘Magnesia-alumina-chrome ramming mixes with same chemical compositions were prepared by using different raw materials such as fused magnesia-chrome synthetic materials and sintered one, wasted bricks and magnesia-alumina spinels. Their physical properties were tested and microstructures were analyzed. The results show that the ramming mixes made of different raw materials bring about different microstructures and properties although the mixes have the same chemical composition, binder content and aggregate size composition.
文摘Al_(2)O_(3)-SiO_(2) based gunning mixes were prepared with electric porcelain waste,silica fume,bauxite,quartz powder,and calcium aluminate cement(CAC)of different additions as raw materials firing at different temperatures to research the effect of the CAC addition on their phase change and properties.The results show that:from theoretical analysis of the phase diagram,with the CAC addition increasing from 8%to 14%,anorthite increases from 40.0%to 77.7%,by mass.With the rising CAC addition,the permanent linear change on heating of specimens increases;for the specimens dried at 110℃or hot-treated at 1000℃,the bulk density and the mechanical properties increase,and the apparent porosity decreases;and for those hottreated at 1300℃,the bulk density and the mechanical properties firstly increase,and then decrease,while the apparent porosity shows an opposite trend.Taking into account the phases at high temperatures and the properties,the optimal CAC addition of Al_(2)O_(3)-SiO_(2) based gunning mixes is 12%.
文摘Current pavement design methods do not allow for the reduction of early deformation of the surface layers of bituminous pavements in the city of Ouagadougou. Weather conditions combined with traffic, particularly during heat waves, are factors. The temperature at the surface of the bituminous pavement can reach 62˚C but the complex modulus associated with this temperature is not taken into account in the design, hence the interest in proposing laws of dependence of the complex moduli is taken into account in the maximum temperatures of the pavement surface. The objective of this paper is to propose an experimental method to determine the temperature dependence of the complex moduli of asphalt mixes for temperatures between 40˚C and 70˚C. This experimental method consists of performing axial compression tests on cylindrical asphalt specimens. It was applied to three different formulas of bituminous mixes, intended for the wearing course, obtained from mixes of crushed granites, granular classes 6/10, 4/6 and 0/4, pure bitumens of grade 50/70, 35/50 and modified bitumen of grade 10/65. The comparative study of the experimental results obtained with the results of a semi-empirical methodology revealed a root mean square deviation from the mean of between 6.58% and 14.8% of the norms of the complex moduli (modulus of rigidity) of the asphalt mixes for a fixed frequency of solicitations of 10 Hz. The consistency of these results with data from the literature led to the initial conclusion that asphalt mixes formulated with 35/50 and 10/65 bitumen would have better compressive strength than those formulated with 50/70 bitumen, for exposure temperatures between 40˚C and 70˚C. This experimental approach could be an alternative to the complex modulus test for determining the modulus of rigidity for design purposes under real pavement exposure conditions in the city of Ouagadougou during heat waves.
基金funded by National Nature Science Foundation of China[grant number 72172041]Social Project by Ministry of Education[grant number 20YJC630022]+1 种基金Shenzhen Philosophy and social science program in 2021[grant number SZ2021D016]University project from Shenzhen Institute of Information Technology in 20212[grant number SZIIT2021SK007].
文摘Evaluating the functional boundary of different types of innovation policy instruments and their mixes on innovation performance of enterprises is an important but unresolved key issue.This paper,based on the systematically carding the quantization of 155 innovation policies issued by Shenzhen governmental departments from 2011 to 2019,analyzed the characteristics from different types of innovation instruments and their mixes.The results show that Shenzhen governmental has constantly enriched innovation policy instruments for encouraging enterprise innovation,but there are structural unbalances in the issued innovation policy manifested as follows:firstly supply-side policy and environmental-side policy were promulgated more than demand-side policy;secondly the specific instruments employed by Shenzhen governmental were also uneven in different type of innovation policy,like supply-side policy focused on the instruments of government procurement and R&D outsourcing,demand-side policy employed human resource training,innovation infrastructure and fiscal support most,and environmental-side policy main used target planning,intellectual property protection and financial support.This study expands and understanding empirical implementation of different reginal innovation policy instruments,and has implication for Shenzhen governmental in improving the applicability ability of policies in the enterprises innovation.
基金National Highways Authority of India(NHAI)for providing financial support to carry out this research。
文摘Properties of aggregates are majorly influenced by parameters of source rocks viz.,formation process,chemical composition,impurities,volume of pores,and grain size.The study presents a review of aggregate treatment methods and its efficacy to enhance the quality of aggregate.Various aspects of aggregate treatment methods like processing temperature,the dosage of additives,adaptability in the field is studied for three treatment methods viz.,polymer coating,cementitious coating,and chemical treatments.The paper also presents an insight to understand the effect of different treatment methods on mix properties and performance parameters of asphalt mixes.The review revealed that the shape properties of aggregates can be enhanced by the incorporating suitable crushing process(two-stage or three-stage).Whereas,physical and durability properties of aggregates can be improved by various treatment methods like polymer coating,Zycosoil treatment.It was further inferred from the review that treatment methods can have moderate effects on the mechanical properties of aggregates,since,it is mostly dependent on properties of source rocks.
文摘This paper deals with Raviart-Thomas element (Q(2,1) x Q(1,2) - Q(1) element). Apart from its global superconvergence property of fourth order, we prove that a postprocessed extrapolation can globally increased the accuracy by fifth order.
基金support by National Key Research and Development Program of China(2022YFB3803502)National Natural Science Foundation of China(52103076)+5 种基金Science and Technology Commission of Shanghai Municipality(23ZR1400300)special fund of Beijing Key Laboratory of Indoor Air Quality Evaluat ion and Control(NO.BZ0344KF21-02)State Key Laboratory of Electrical Insulation and Power Equipment(EIPE22203)JLF is a member of LSRE-LCM–Laboratory of Separation and Reaction Engineering-Laboratory of Catalysis and Materials,supported by national funds through FCT/MCTES(PIDDAC):LSRE-LCM,UIDB/50020/2020(DOI:10.54499/UIDB/50020/2020)UIDP/50020/2020(DOI:10.54499/UIDP/50020/2020)ALiCE,LA/P/0045/2020(DOI:10.54499/LA/P/0045/2020).
文摘Direct seawater splitting has emerged as a popular and promising research direction for synthesising clean,green,non-polluting,and sustainable hydrogen energy without depending on high-purity water in the face of the world’s shortage of fossil energy.However,efficient seawater splitting is hindered by slow kinetics caused by the ultra-low conductivity and the presence of bacteria,microorganisms,and stray ions in seawater.Additionally,producing hydrogen on an industrial scale is challenging due to the high production cost.The present review addresses these challenges from the catalyst point of view,namely,that designing catalysts with high catalytic activity and stability can directly affect the rate and effect of seawater splitting.From the ion transfer perspective,designing membranes can block harmful ions,improving the stability of seawater splitting.From the energy point of view,mixed seawater systems and self-powered systems also provide new and low-energy research systems for seawater splitting.Finally,ideas and directions for further research on direct seawater splitting in the future are pointed out,with the aim of achieving low-cost and high-efficiency hydrogen production.
基金Funded by Science and Technology Development Project of China Railway Design Corporation(Nos.2023A0226407,2023B03040003)。
文摘Paste and mortar specimens were prepared with sulfoaluminate cement(SAC),P⋅O 42.5 ordinary Portland cement(OPC),and standard sand,and mixed and cured with pure water and artificial seawater,respectively.The mechanical properties of mortar specimens were tested.Hydration and microstructure of paste specimens were also investigated using X-ray diffraction(XRD),scanning electron microscope(SEM),and 27Al nuclear magnetic resonance(NMR),respectively.The results indicate that SAC mortar samples mixed and cured by seawater have faster strength growth before 28 d and higher compressive strength than OPC mortar samples.Compared to curing in deionized water,the hydration products of SAC are somewhat coarser when cured in simulated seawater.The evolution of aluminum phase hydration products during the hydration process of SAC mixed and cured in simulated seawater is quite different from that of OPC.From 3 to 28 d,the content of each aluminum phase hydration product in SAC paste cured in simulated seawater changed little,while that in OPC paste changed significantly;for example,from 7 to 28 d,the content of ettringite(AFt)in OPC paste increased significantly.This type of AFt formed loosely,harming the mortar's microstructure.
基金financial support from the National Natural Science Foundation of China(Nos.22108258 and 52003251)Program for Science&Technology Innovation Talents in Universities of Henan Province(24HASTIT004)+1 种基金Outstanding Youth Fund of Henan Scientific Committee(222300420085)Science and Technology Joint Project of Henan Province(222301420041)。
文摘Mixed matrix membranes(MMMs)have demonstrated significant promise in energy-intensive gas separations by amalgamating the unique properties of fillers with the facile processability of polymers.However,achieving a simultaneous enhancement of permeability and selectivity remains a formidable challenge,due to the difficulty of achieving an optimal match between polymers and fillers.In this study,we incorporate a porous carbon-based zinc oxide composite(C@ZnO)into high-permeability polymers of intrinsic microporosity(PIMs)to fabricate MMMs.The dipole–dipole interaction between C@ZnO and PIMs ensures their exceptional compatibility,mitigating the formation of non-selective voids in the resulting MMMs.Concurrently,C@ZnO with abundant interconnected pores can provide additional low-resistance pathways for gas transport in MMMs.As a result,the CO_(2) permeability of the optimized C@ZnO/PIM-1 MMMs is elevated to 13,215 barrer,while the CO_(2)/N_(2) and CO_(2)/CH_(4) selectivity reached 21.5 and 14.4,respectively,substantially surpassing the 2008 Robeson upper bound.Additionally,molecular simulation results further corroborate that the augmented membrane gas selectivity is attributed to the superior CO_(2) affinity of C@ZnO.In summary,we believe that this work not only expands the application of MMMs for gas separation but also heralds a paradigm shift in the application of porous carbon materials.
文摘An aluminoborate,Na_(2.5)Rb[Al{B_(5)O_(10)}{B_(3)O_(5)}]·0.5NO_(3)·H_(2)O(1),was synthesized under hydrothermal condition,which was built by mixed oxoboron clusters and AlO_(4)tetrahedra.In the structure,the[B_(5)O_(10)]^(5-)and[B_(3)O_(7)]^(5-)clusters are alternately connected to form 1D[B_(8)O_(15)]_(n)^(6n-)chains,which are further linked by AlO_(4)units to form a 2D monolayer with 7‑membered ring and 10‑membered ring windows.Two adjacent monolayers with opposite orientations further form a porous‑layered structure with six channels through B—O—Al bonds.Compound 1 was characterized by single crystal X‑ray diffraction,powder X‑ray diffraction(PXRD),IR spectroscopy,UV‑Vis diffuse reflection spectroscopy,and thermogravimetric analysis(TGA),respectively.UV‑Vis diffuse reflectance analysis indicates that compound 1 shows a wide transparency range with a short cutoff edge of 201 nm,suggesting it may have potential application in UV regions.CCDC:2383923.
基金IPR,Gandhinagar,Gujarat,IndiaKIIT Deemed to be University,India for supporting。
文摘Hybrid nanofluids are known for their attractive thermophysical properties and enhanced heat transfer potential.This study thoroughly investigates the impact of particle mixing ratios on the thermophysical and heat transfer characteristics of MgO-SiO_(2)/water hybrid nanofluid.The mixing mass ratio(MR)of MgO:SiO_(2)was systematically altered including ratios of 100:0,80:20,60:40,50:50,40:60,20:80,and 0:100 at a fixed particle concentration of 0.01%in volume.Experimental assessments of thermal conductivity and viscosity were conducted within the temperature range of 25℃-50℃at 5℃intervals.Thermal conductivity was measured by analysing sonic velocity of sound in nanofluid medium.Viscosity was determined by Ostwald viscosity apparatus.Sensitivity analysis was performed to examine the influence of mixing ratio and temperature on thermal conductivity and viscosity.Sustainability and economic analysis were conducted to guide future applications.The findings highlight the substantial influence of MR on thermal conductivity and viscosity enhancements within the hybrid nanofluid.The thermal conductivity exhibited a positive correlation with temperature elevation,with the hybrid nanofluid at MR=60:40 and 50℃displaying the highest thermal conductivity enhancement at 20.84%compared to water.In contrast,viscosity decreased with increasing temperature,with MR=50:50 at 50℃showing the maximum viscosity increase at 5.06%compared to water.New data-driven correlations for precise predictions of thermal conductivity and viscosity of hybrid nanofluid have been proposed.Sensitivity analysis revealed that mixing ratio had a more pronounced impact than temperature elevation.Sustainability and economic analysis concludes that MR=60:40 is an optimal,economical and sustainable choice for achieving peak heat transfer performance.
基金supported by the National Natural Science Foundation of China(Grant no.42176244)CAS Key Deployment Project of Centre for Ocean Mega-Research of Science(Grant no.COMS2020Q07)。
文摘In the Arctic Ocean,turbulent mixing drives vertical heat flux,thereby affecting the sea ice variability.Internal wave is regarded as one of the important energy sources of mixing in this region.The high latitude and sea ice cover make internal wave in the Arctic Ocean apparently differs from that in mid-and low-latitude oceans.However,the internal wave and its underlying mechanism are less understood due to the lack of observations.This paper briefly reviews the recent studies and unresolved questions on the internal wave in the Arctic Ocean,including wind-driven near-inertial wave,internal tide,and high-frequency internal wave.The aim is to provide new insights for in-depth research in the future,with a focus on the mechanisms responsible for the evolution of internal wave under the rapidly changing Arctic climate.
文摘This work focuses on a Keller-Segel chemotaxis model, with an emphasis on its conservation laws. Through a new approach combined with the multiplier method, called the mixed method, we obtain conservation vectors that are related and unrelated to symmetric information. In addition, some exact solutions with particular forms are obtained according to the method of conservation laws. These particular solutions are different from the group-invariant solutions.
文摘DNA microarray technology is an extremely effective technique for studying gene expression patterns in cells, and the main challenge currently faced by this technology is how to analyze the large amount of gene expression data generated. To address this, this paper employs a mixed-effects model to analyze gene expression data. In terms of data selection, 1176 genes from the white mouse gene expression dataset under two experimental conditions were chosen, setting up two conditions: pneumococcal infection and no infection, and constructing a mixed-effects model. After preprocessing the gene chip information, the data were imported into the model, preliminary results were calculated, and permutation tests were performed to biologically validate the preliminary results using GSEA. The final dataset consists of 20 groups of gene expression data from pneumococcal infection, which categorizes functionally related genes based on the similarity of their expression profiles, facilitating the study of genes with unknown functions.
基金the National Nature Science Foundation of China(Grant Nos.42077435 and 42377171).
文摘This study elucidates the findings of a computational investigation into the stimulation characteristics of natural reservoir systems enhanced by high-voltage electropulse-assisted fluid injection.The presented methodology delineates the comprehensive rock-fracturing process induced by electropulse and subsequent fluid injection,encompassing the discharge circuit,plasma channel formation,shockwave propagation,and hydro-mechanical response.A hydromechanical model incorporating an anisotropic plastic damage constitutive law,discrete fracture networks,and heterogeneous distribution is developed to represent the natural reservoir system.The results demonstrate that high-voltage electropulse effectively generates intricate fracture networks,significantly enhances the hydraulic properties of reservoir systems,and mitigates the adverse impact of ground stress on fracturing.The stimulationenhancing effect of electropulse is observed to intensify with increasing discharge voltage,with enhancements of 118.0%,139.5%,and 169.0%corresponding to discharge voltages of 20 kV,40 kV,and 60 kV,respectively.Additionally,a high-voltage electropulse with an initial voltage of U_(0)=80 kV and capacitance C=5μF has been shown to augment the efficiency of injection activation to approximately 201.1%compared to scenarios without electropulse.Under the influence of high-voltage electropulse,the fluid pressure distribution diverges from the conventional single direction of maximum stress,extending over larger areas.These innovative methods and findings hold potential implications for optimizing reservoir stimulation in geo-energy engineering.
