Correlations of soil properties and fruit size of Calligonum mongolicum Turcz. and related species were analyzed. The resullLs showed that the particle size characteristics of soils for growing Calligonum mongolicum a...Correlations of soil properties and fruit size of Calligonum mongolicum Turcz. and related species were analyzed. The resullLs showed that the particle size characteristics of soils for growing Calligonum mongolicum and related species were similar, and the soils belonged to sandyones. The organic matter contents of soils were low (averaging 1.772 to 3.054 g/kg), and the total salt content of soils was low too (averaging 0.471 g/kg). The pH values indicated that the soils were alkaline, varying from pH 7.65 to 10.25. The results of Principal Component Analysis (PCA) and hierarchical cluster showed that 9 habitats could be divided into 6 types according to salt contents and pH values. Fruit sizes of different populations and the soil properties had significant linear correlations (P〈0.000). It was concluded that the differences in fruit sizes among the populations of Calligonum mongolicum and related species werre related to soil variability, especially the nutrient contents of soils, and fruit size can not be considered as a taxonomic index of Calligonum mongofcum and related species.展开更多
High-frequency magnetic properties, such as core loss, coercivity and amplitude permeabilityof a newly-developed nanocrystalline Fe72.5Cu1Nb2V2Si13.5B9 alloy in the wide ranges of f =20-103 kHz, Bm = 0.01~0.6 T and Bm...High-frequency magnetic properties, such as core loss, coercivity and amplitude permeabilityof a newly-developed nanocrystalline Fe72.5Cu1Nb2V2Si13.5B9 alloy in the wide ranges of f =20-103 kHz, Bm = 0.01~0.6 T and Bmf = 10~40 (T.kHz) have been measured. A largeamount of experimental data have been fitted by a computer, thus obtaining several expressionsrepresenting the influence of frequency on high-frequency magnetic properties, that are useful inpractical applications.展开更多
Samples of 12 hard winter wheats and their flours that produced breads varying in crumb grain scores were studied for 38 quality parameters including: wheat physical and chemical characteristics; flour ash and protein...Samples of 12 hard winter wheats and their flours that produced breads varying in crumb grain scores were studied for 38 quality parameters including: wheat physical and chemical characteristics; flour ash and protein contents,starch damage,swelling power,pasting characteristics,and flour particle size distribution; dough properties determined by a mixograph; and breadmaking properties for pup loaves (100g flour). Only two parameters,the protein content of wheat and the granulation of flour,showed significant correlations with bread crumb grain scores. Protein content of wheat ranging 12.9%~14.5% determined by an NIR method showed a weak inverse relationship (r =-0.61,p<0.05) with bread crumb grain score. Flour particle size distribution measured by both Alpine Air Jet Sieve and NIR methods revealed that the weight wt % of particles less than 38μm in size and representing 9.6%~19.3% of the flour weights was correlated positively (r =0 .78,p<0.01) with crumb grain score,whereas wt % of flour particles larger than 125μm had an inverse relationship (r =-0.60,p<0.05) with crumb grain score.展开更多
With the wide applications of sensor network technology in traffic information acquisition systems,a new measure will be quite necessary to evaluate spatially related properties of traffic information credibility.The ...With the wide applications of sensor network technology in traffic information acquisition systems,a new measure will be quite necessary to evaluate spatially related properties of traffic information credibility.The heterogeneity of spatial distribution of information credibility from sensor networks is analyzed and a new measure,information credibility function(ICF),is proposed to describe this heterogeneity.Three possible functional forms of sensor ICF and their corresponding expressions are presented.Then,two feasible operations of spatial superposition of sensor ICFs are discussed.Finally,a numerical example is introduced to show the calibration method of sensor ICF and obtain the spatially related properties of expressway in Beijing.The results show that the sensor ICF of expressway in Beijing possesses a negative exponent property.The traffic information is more abundant at or near the locations of sensor,while with the distance away from the sensor increasing,the traffic information credibility will be declined by an exponential trend.The new measure provides theoretical bases for the optimal locations of traffic sensor networks and the mechanism research of spatial distribution of traffic information credibility.展开更多
The thermodynamic properties of xanthone(XTH) and 135 polybrominated xanthones(PBXTHs) in the standard state have been calculated at the B3LYP/6-31G* level using Gaussian 03 program.The isodesmic reactions were d...The thermodynamic properties of xanthone(XTH) and 135 polybrominated xanthones(PBXTHs) in the standard state have been calculated at the B3LYP/6-31G* level using Gaussian 03 program.The isodesmic reactions were designed to calculate the standard enthalpy of formation(△fHθ) and standard free energy of formation(△fGθ) of PBXTH congeners.The relations of these thermodynamic parameters with the number and position of Br atom substitution(NPBS) were discussed,and it was found that there exist high correlation between thermodynamic parameters(entropy(Sθ),△fHθ and △fGθ) and NPBS.According to the relative magnitude of their △fGθ,the relative stability order of PBXTH congeners was theoretically proposed.The relative rate constants of formation reactions of PBXTH congeners were calculated,Moreover,the values of molar heat capacity at constant pressure(Cp,m) from 200 to 1000 K for PBXTH congeners were also calculated,and the temperature dependence relation of them was obtained,suggesting very good relationships between Cp,m and temperature(T,T^1 and T^2) for almost all PBXTH congeners.展开更多
With the aim that to confirm the need for humidity control in the environment in which textile sample are visually and instrumentally analyzed, three different pre-conditioned fabrics sample of cotton, polyester and s...With the aim that to confirm the need for humidity control in the environment in which textile sample are visually and instrumentally analyzed, three different pre-conditioned fabrics sample of cotton, polyester and silk were treated at a fix temperature of 21?C. The relative humidity adjusted to four levels: 55%, 65%, 75% and 85% RH for a conditioning time of 24 hours as specified in ASTM D-1776-98. It has been observed that as the relative humidity increase from 55% to 85% cotton increase its tensile strength, silk losses its strength and there was no significant change observed in the tensile strength of polyester fabric.展开更多
Schottky diodes and PN junctions were utilized as energy converting structures in ZnO-based betavoltaic batteries,in which 0.101121 Ci 63Ni was selected as the beta source.The time-related electrical properties were o...Schottky diodes and PN junctions were utilized as energy converting structures in ZnO-based betavoltaic batteries,in which 0.101121 Ci 63Ni was selected as the beta source.The time-related electrical properties were obtained using Monte Carlo simulations.For the n-type ZnO,the Pt/ZnO Schottky diode had the highest energy conversion efficiency,and the Ni/ZnO Schottky diode had the largest Isc.The overall electrical performance of PN junctions is better than that of Schottky diodes.The lifetimes of Pt/ZnO and Ni/ZnO are longer than for other Schottky devices,coming close to those of PN junctions.Considering that Schottky diodes are easier to fabricate and independent of p-type semiconductors,Pt/ZnO and Ni/ZnO diodes offer alternatives to PN-junction-based betavoltaic batteries.展开更多
In this paper, we investigate Kazhdan’s relative Property (T) for pairs , where is a topological group and is any subset of . We show that the pair has Property (FH) and every function conditionally of negative type ...In this paper, we investigate Kazhdan’s relative Property (T) for pairs , where is a topological group and is any subset of . We show that the pair has Property (FH) and every function conditionally of negative type on is X-bounded if the pair has relative Property (T). We also prove that has Property (T) whenis a s -compact locally compact group generated by its subgroups and the pair has relative Property (T) for all .展开更多
MatBase is a prototype data and knowledge base management expert intelligent system based on the Relational,Entity-Relationship,and(Elementary)Mathematical Data Models.Dyadic relationships are quite common in data mod...MatBase is a prototype data and knowledge base management expert intelligent system based on the Relational,Entity-Relationship,and(Elementary)Mathematical Data Models.Dyadic relationships are quite common in data modeling.Besides their relational-type constraints,they often exhibit mathematical properties that are not covered by the Relational Data Model.This paper presents and discusses the MatBase algorithm that assists database designers in discovering all non-relational constraints associated to them,as well as its algorithm for enforcing them,thus providing a significantly higher degree of data quality.展开更多
In order to investigate the degradation of bonding properties between corroded steel bars and concrete,this study employs the half-beam method to conduct bond-slip tests between corroded steel bars and concrete after ...In order to investigate the degradation of bonding properties between corroded steel bars and concrete,this study employs the half-beam method to conduct bond-slip tests between corroded steel bars and concrete after impressed-current accelerated corrosion of the steel bars in concrete.The effects of steel corrosion rate,steel bar diameter,steel bar strength grade,and concrete strength grade on the bonding properties between concrete and corroded steel bars were analyzed.The influence of different corrosion rates on specimens’bonding strength and bond-slip curves was determined,and a constitutive relationship for bond-slip between corroded steel bars and concrete was proposed.The results indicate that the ultimate bonding strength of corroded reinforced concrete specimens decreases with increasing corrosion rate.Additionally,an increase in corrosive crack width leads to a linear decrease in bonding strength.Evaluating the decline in adhesive properties through rust expansion crack width in engineering applications is feasible.Furthermore,a bond-slip constitutive relationship between corroded steel bars and concrete was established using relative bond stress and relative slip values,which aligned well with the experimental findings.展开更多
Open-cell nickel foams with different relative densities and pre-stretching degrees were subjected to room temperature quasi-static compressive tests to explore their compressive properties. The compressive properties...Open-cell nickel foams with different relative densities and pre-stretching degrees were subjected to room temperature quasi-static compressive tests to explore their compressive properties. The compressive properties of the nickel foams including yield strength, elastic modulus, energy absorption density and energy absorption efficiency were calculated accurately. The results show that the compressive properties of yield strength, elastic modulus and energy absorption density increase with the increase of relative density of nickel foams. The compressive properties are sensitive to the pre-stretching degree, and the values of yield strength, elastic modulus and energy absorption density decrease with the increase of pre-stretching degree. However, the energy absorption efficiency at the densification strain state exhibits the independence of relative density and pre-stretching degree. The value of energy absorption efficiency reaches its peak when the strain is at the end of the collapse plateau region.展开更多
The mechanical properties and constitutive behaviors of as-cast AA7050 in both the solid and semi-solid states were determined using the on-cooling and in situ solidification approaches, respectively. The results show...The mechanical properties and constitutive behaviors of as-cast AA7050 in both the solid and semi-solid states were determined using the on-cooling and in situ solidification approaches, respectively. The results show that the strength in the solid state tends to increase with decreasing temperature. The strain rate plays an important role in the stress–strain behaviors at higher temperatures, whereas the influence becomes less pronounced and irregular when the temperature is less than 250°C. The experimental data were fitted to the extended Ludwik equation, which is suitable to describe the mechanical behavior of the materials in the as-cast state. In the semi-solid state, both the strength and ductility of the alloy are high near the solidus temperature and decrease drastically with decreasing solid fraction. As the solid fraction is less than 0.97, the maximum strength only slightly decreases, whereas the post-peak ductility begins to increase. The experimental data were fitted to the modified creep law, which is used to describe the mechanical behavior of semi-solid materials, to determine the equivalent parameter fGBWL, i.e., the fraction of grain boundaries covered by liquid phase.展开更多
Geometric structures of 135 polychlorinated fluorene (PCFR) molecules were optimized using density functional theory (DFT) at the B3LYP/6-311G** level and their thermodynamic properties in the ideal gas state we...Geometric structures of 135 polychlorinated fluorene (PCFR) molecules were optimized using density functional theory (DFT) at the B3LYP/6-311G** level and their thermodynamic properties in the ideal gas state were calculated. The relations of these thermodynamic properties with the number and position of chlorine atoms were also explored, from which the relative stability of PCFR congeners was theoretically proposed according to the magnitude of the relative standard Gibbs free energy of formation (Δr,fGθ). The results show that the geometric configuration of PCFR isomers is determined by the position of chlorine atoms. There exist two types of intramolecular weak interactions, i.e., C–H···Cl and Cl···Cl interactions in PCFR molecules. The change of ΔfHθ and ΔfGθ of most stable PCFR isomers with increasing the number of chlorine atoms is different from that in most unstable PCFR congeners. The values of ΔfHθ and ΔfGθ for PCFR isomers with the same number of chlorine atoms strongly depend on the position of chlorine atoms and the relative stability of PCFR congeners is mainly determined by intramolecular delocalized π bond and Cl···Cl nuclear repulsive interaction.展开更多
To investigate the mechanical properties of cement mortar in sodium sulfate and sodium chloride solutions, uniaxial compression test and ultrasonic test were performed. Test results show that the relative dynamic elas...To investigate the mechanical properties of cement mortar in sodium sulfate and sodium chloride solutions, uniaxial compression test and ultrasonic test were performed. Test results show that the relative dynamic elastic modulus, the mass variation,and the compressive strength of cement mortar increase first, and then decrease with increasing erosion time in sodium sulfate and sodium chloride solutions. The relative dynamic elastic moduli and the compressive strengths of cement mortars with water/cement ratios of 0.55 and 0.65 in sodium sulfate solution are lower than those in sodium chloride solution with the same concentration at the420 th day of immersion. The compressive strength of cement mortar with water/cement ratio of 0.65 is more sensitive to strain rate than that with water/cement ratio of 0.55. In addition, the strain-rate sensitivity of compressive strength of cement mortar will increase under attacks of sodium sulfate or sodium chloride solution.展开更多
In order to study the sintering characteristics of Ca-rich iron ore,chemical analysis,laser diffraction,scanning electron microscopy,XRD-Rietveld method,and micro-sintering were used to analyze the mineralogical prope...In order to study the sintering characteristics of Ca-rich iron ore,chemical analysis,laser diffraction,scanning electron microscopy,XRD-Rietveld method,and micro-sintering were used to analyze the mineralogical properties and sintering pot tests were used to study the sintering behavior.In addition,a grey correlation mathematical model was used to calculate and compare the comprehensive sintering performance under different calcium-rich iron ore contents.The results demonstrate that the Ca-rich iron ore has coarse grain size and strong self-fusing characteristics with Ca element in the form of calcite(CaCO_(3)) and the liquid phase produced by the self-fusing of the calcium-rich iron ore is well crystallized.Its application with a 20wt%content in sintering improves sinter productivity,reduces fuel consumption,enhances reduction index,and improves gas permeability in blast furnace by 0.45 t/(m^(2)·h),6.11 kg/t,6.17%,and 65.39 kPa·℃,respectively.The Ca-rich iron ore sintering can improve the calorific value of sintering flue gas compared with magnetite sintering,which is conducive to recovering heat for secondary use.As the content of the Ca-rich iron ore increases,sinter agglomeration shifts from localized liquid-phase bonding to a combination of localized liquid-phase bonding and iron oxide crystal connection.Based on an examination of the greater weight value of productivity with grey correlation analysis,the Ca-rich iron ore is beneficial for the comprehensive index of sintering in the range of 0-20wt%content.Therefore,it may be used in sintering with magnetite concentrates as the major ore species.展开更多
The gas phase thermodynamic properties of 135 polychlorinated xanthones(PCXTs)are calculated using a combination of quantum mechanical computations performed with the Gaussian 03 program at the B3LYP/6-311G**level.It ...The gas phase thermodynamic properties of 135 polychlorinated xanthones(PCXTs)are calculated using a combination of quantum mechanical computations performed with the Gaussian 03 program at the B3LYP/6-311G**level.It is found that the chlorine substitution pattern strongly influences the thermodynamic properties of the compounds.The thermodynamic properties of congeners with the same number of chlorines also depend on the chlorine substitution pattern,especially for ortho-substituted congeners.PCXT congeners with one phenyl ring fully chlorinated are found to be the least stable among the analogues.The effect of the chlorine substitution pattern is quantitatively studied by considering the number and position of Cl atom substitution(NPCS).The results show that the NPCS model may be used to predict the thermodynamic properties for all 135 PCXT congeners. In addition,the values of molar heat capacities at constant pressure(cp,m)from 200 to 1000 K for PCXT congeners are calculated,and the temperature dependence relation of this parameter is obtained using the least-squares method.展开更多
Al7075-Cu composite joints were prepared by the squeeze overcast process.The effects of melt temperature,die temperature,and squeeze pressure on hardness and ultimate tensile strength(UTS)of squeeze overcast Al7075-Cu...Al7075-Cu composite joints were prepared by the squeeze overcast process.The effects of melt temperature,die temperature,and squeeze pressure on hardness and ultimate tensile strength(UTS)of squeeze overcast Al7075-Cu composite joints were studied.The experimental results depict that squeeze pressure is the most significant process parameter affecting the hardness and UTS.The optimal values of UTS(48 MPa)and hardness(76 HRB)are achieved at a melt temperature of 800℃,a die temperature of 250℃,and a squeeze pressure of 90 MPa.Scanning electron microscopy(SEM)shows that fractured surfaces show flatfaced morphology at the optimal experimental condition.Energy-dispersive spectroscopy(EDS)analysis depicts that the atomic weight percentage of Zn decreases with an increase in melt temperature and squeeze pressure.The optimal mechanical properties of the Al7075-Cu overcast joint were achieved at the Al2Cu eutectic phase due to the large number of copper atoms that dispersed into the aluminum melt during the solidification process and the formation of strong intermetallic bonds.Gray relational analysis integrated with the Taguchi method was used to develop an optimal set of control variables for multi-response parametric optimization.Confirmatory tests were performed to validate the effectiveness of the employed technique.The manufacturing of squeeze overcast Al7075-Cu composite joints at optimal process parameters delivers a great indication to acknowledge a new method for foundry practitioners to manufacture materials with superior mechanical properties.展开更多
Light is crucial to the uniform production of high-quality fruit since it is the driving force for leaf photosynthesis and hence overall plant nutrition.The objective of this study was to evaluate the relationship bet...Light is crucial to the uniform production of high-quality fruit since it is the driving force for leaf photosynthesis and hence overall plant nutrition.The objective of this study was to evaluate the relationship between the distribution of relative light intensity in the peach tree(Prunus persica)canopy and the yield and texture of peach fruits.The canopy of 7-year-old‘Qiuyan’was divided into cubical volumes and the relative light intensity distribution was measured for each cube,along with yield distribution and fruit textural properties at different growing times.The relative light intensity decreased gradually from outside to inside the canopy and from top to bottom.The yield distribution and the relative light intensity were clearly correlated.The percentage of the canopy receiving<30%relative light intensity was 49.07%in May,56.02%in June,and 58.95%in July,whereas the percentage receiving>80%relative light intensity was 32.72%,17.28%,and 10.96%,respectively.Consistent with this,peaches were found in the upper and middle portions of the canopy,within 1.5-3.0 m of the top.The regression equation showed that fruit texture index correlated significantly with relative light intensity.Relative light intensity is the main factor affecting peach yield and texture and must be above 41.83%for good peach quality.Orchardists should carefully plan summer pruning strategies to adjust the number and spatial distribution of branches accordingly.展开更多
Constant weight code is an important error-correcting control code in communications. Basic structure of constant weight codes for some arriving at Johnson bound, A(n, 2u, w), is presented. Some correlative property...Constant weight code is an important error-correcting control code in communications. Basic structure of constant weight codes for some arriving at Johnson bound, A(n, 2u, w), is presented. Some correlative propertys of the codes, the solution of arriving at Johnson bound, and the results on the couple constant code and some constant weight codes are discussed. The conclusion is verified through four examples.展开更多
The relationships between the selective laser melting(SLM)processing parameters including laser power,scanning speed and hatch space,the relative density,the microstructure,and resulting mechanical properties of Ti-6A...The relationships between the selective laser melting(SLM)processing parameters including laser power,scanning speed and hatch space,the relative density,the microstructure,and resulting mechanical properties of Ti-6Al-2Zr-1Mo-1V alloy were investigated in this work.The result shows that laser power acts a dominant role in determining the relative density in comparison with scanning speed and hatch space.The optimal SLM process window for fabricating relative density>99%samples is located in the energy density range of 34.72 J·mm^(-3)to 52.08 J·mm^(-3),where the laser power range is between 125 W and 175 W.An upward trend is found in the micro-hardness as the energy density is increased.The optimum SLM processing parameters of Ti-6Al-2Zr-1Mo-1V alloy are:laser power of 150 W,scanning speed of 1,600 mm·s^(-1),hatch space of 0.08 mm,and layer thickness of 0.03 mm.The highest ultimate tensile strength,yield strength,and ductility under the optimum processing parameter are achieved,which are 1,205 MPa,1,099 MPa,and 8%,respectively.The results of this study can be used to guide SLM production Ti-6Al-2Zr-1Mo-1V alloy parts.展开更多
基金supported by the National Natural Science Foundation of China (Grant No 31100150)the West Light Talents Cultivation Program of Chinese Academy of Sciences(XBBS 201003)
文摘Correlations of soil properties and fruit size of Calligonum mongolicum Turcz. and related species were analyzed. The resullLs showed that the particle size characteristics of soils for growing Calligonum mongolicum and related species were similar, and the soils belonged to sandyones. The organic matter contents of soils were low (averaging 1.772 to 3.054 g/kg), and the total salt content of soils was low too (averaging 0.471 g/kg). The pH values indicated that the soils were alkaline, varying from pH 7.65 to 10.25. The results of Principal Component Analysis (PCA) and hierarchical cluster showed that 9 habitats could be divided into 6 types according to salt contents and pH values. Fruit sizes of different populations and the soil properties had significant linear correlations (P〈0.000). It was concluded that the differences in fruit sizes among the populations of Calligonum mongolicum and related species werre related to soil variability, especially the nutrient contents of soils, and fruit size can not be considered as a taxonomic index of Calligonum mongofcum and related species.
文摘High-frequency magnetic properties, such as core loss, coercivity and amplitude permeabilityof a newly-developed nanocrystalline Fe72.5Cu1Nb2V2Si13.5B9 alloy in the wide ranges of f =20-103 kHz, Bm = 0.01~0.6 T and Bmf = 10~40 (T.kHz) have been measured. A largeamount of experimental data have been fitted by a computer, thus obtaining several expressionsrepresenting the influence of frequency on high-frequency magnetic properties, that are useful inpractical applications.
文摘Samples of 12 hard winter wheats and their flours that produced breads varying in crumb grain scores were studied for 38 quality parameters including: wheat physical and chemical characteristics; flour ash and protein contents,starch damage,swelling power,pasting characteristics,and flour particle size distribution; dough properties determined by a mixograph; and breadmaking properties for pup loaves (100g flour). Only two parameters,the protein content of wheat and the granulation of flour,showed significant correlations with bread crumb grain scores. Protein content of wheat ranging 12.9%~14.5% determined by an NIR method showed a weak inverse relationship (r =-0.61,p<0.05) with bread crumb grain score. Flour particle size distribution measured by both Alpine Air Jet Sieve and NIR methods revealed that the weight wt % of particles less than 38μm in size and representing 9.6%~19.3% of the flour weights was correlated positively (r =0 .78,p<0.01) with crumb grain score,whereas wt % of flour particles larger than 125μm had an inverse relationship (r =-0.60,p<0.05) with crumb grain score.
基金Project(61104164)supported by the National Natural Science Foundation of ChinaProject(2012AA112401)supported by the National High Technology Research and Development Program of ChinaProject(2012YJS059)supported by the Fundamental Research Funds for the Central Universities of China
文摘With the wide applications of sensor network technology in traffic information acquisition systems,a new measure will be quite necessary to evaluate spatially related properties of traffic information credibility.The heterogeneity of spatial distribution of information credibility from sensor networks is analyzed and a new measure,information credibility function(ICF),is proposed to describe this heterogeneity.Three possible functional forms of sensor ICF and their corresponding expressions are presented.Then,two feasible operations of spatial superposition of sensor ICFs are discussed.Finally,a numerical example is introduced to show the calibration method of sensor ICF and obtain the spatially related properties of expressway in Beijing.The results show that the sensor ICF of expressway in Beijing possesses a negative exponent property.The traffic information is more abundant at or near the locations of sensor,while with the distance away from the sensor increasing,the traffic information credibility will be declined by an exponential trend.The new measure provides theoretical bases for the optimal locations of traffic sensor networks and the mechanism research of spatial distribution of traffic information credibility.
基金Supported by the NNSFC (20737001, 20977046)NSF of Zhejiang Province (2008Y507280)
文摘The thermodynamic properties of xanthone(XTH) and 135 polybrominated xanthones(PBXTHs) in the standard state have been calculated at the B3LYP/6-31G* level using Gaussian 03 program.The isodesmic reactions were designed to calculate the standard enthalpy of formation(△fHθ) and standard free energy of formation(△fGθ) of PBXTH congeners.The relations of these thermodynamic parameters with the number and position of Br atom substitution(NPBS) were discussed,and it was found that there exist high correlation between thermodynamic parameters(entropy(Sθ),△fHθ and △fGθ) and NPBS.According to the relative magnitude of their △fGθ,the relative stability order of PBXTH congeners was theoretically proposed.The relative rate constants of formation reactions of PBXTH congeners were calculated,Moreover,the values of molar heat capacity at constant pressure(Cp,m) from 200 to 1000 K for PBXTH congeners were also calculated,and the temperature dependence relation of them was obtained,suggesting very good relationships between Cp,m and temperature(T,T^1 and T^2) for almost all PBXTH congeners.
文摘With the aim that to confirm the need for humidity control in the environment in which textile sample are visually and instrumentally analyzed, three different pre-conditioned fabrics sample of cotton, polyester and silk were treated at a fix temperature of 21?C. The relative humidity adjusted to four levels: 55%, 65%, 75% and 85% RH for a conditioning time of 24 hours as specified in ASTM D-1776-98. It has been observed that as the relative humidity increase from 55% to 85% cotton increase its tensile strength, silk losses its strength and there was no significant change observed in the tensile strength of polyester fabric.
基金supported by the National Major Scientific Instruments and Equipment Development Projects(No.2012YQ240121)National Natural Science Foundation of China(No.11075064)
文摘Schottky diodes and PN junctions were utilized as energy converting structures in ZnO-based betavoltaic batteries,in which 0.101121 Ci 63Ni was selected as the beta source.The time-related electrical properties were obtained using Monte Carlo simulations.For the n-type ZnO,the Pt/ZnO Schottky diode had the highest energy conversion efficiency,and the Ni/ZnO Schottky diode had the largest Isc.The overall electrical performance of PN junctions is better than that of Schottky diodes.The lifetimes of Pt/ZnO and Ni/ZnO are longer than for other Schottky devices,coming close to those of PN junctions.Considering that Schottky diodes are easier to fabricate and independent of p-type semiconductors,Pt/ZnO and Ni/ZnO diodes offer alternatives to PN-junction-based betavoltaic batteries.
文摘In this paper, we investigate Kazhdan’s relative Property (T) for pairs , where is a topological group and is any subset of . We show that the pair has Property (FH) and every function conditionally of negative type on is X-bounded if the pair has relative Property (T). We also prove that has Property (T) whenis a s -compact locally compact group generated by its subgroups and the pair has relative Property (T) for all .
文摘MatBase is a prototype data and knowledge base management expert intelligent system based on the Relational,Entity-Relationship,and(Elementary)Mathematical Data Models.Dyadic relationships are quite common in data modeling.Besides their relational-type constraints,they often exhibit mathematical properties that are not covered by the Relational Data Model.This paper presents and discusses the MatBase algorithm that assists database designers in discovering all non-relational constraints associated to them,as well as its algorithm for enforcing them,thus providing a significantly higher degree of data quality.
基金Scientific Research Fund of Hunan Provincial Education Department(21A0123)。
文摘In order to investigate the degradation of bonding properties between corroded steel bars and concrete,this study employs the half-beam method to conduct bond-slip tests between corroded steel bars and concrete after impressed-current accelerated corrosion of the steel bars in concrete.The effects of steel corrosion rate,steel bar diameter,steel bar strength grade,and concrete strength grade on the bonding properties between concrete and corroded steel bars were analyzed.The influence of different corrosion rates on specimens’bonding strength and bond-slip curves was determined,and a constitutive relationship for bond-slip between corroded steel bars and concrete was proposed.The results indicate that the ultimate bonding strength of corroded reinforced concrete specimens decreases with increasing corrosion rate.Additionally,an increase in corrosive crack width leads to a linear decrease in bonding strength.Evaluating the decline in adhesive properties through rust expansion crack width in engineering applications is feasible.Furthermore,a bond-slip constitutive relationship between corroded steel bars and concrete was established using relative bond stress and relative slip values,which aligned well with the experimental findings.
基金Project supported by the 2015 Shandong Province Project of Outstanding Subject Talent Group
文摘Open-cell nickel foams with different relative densities and pre-stretching degrees were subjected to room temperature quasi-static compressive tests to explore their compressive properties. The compressive properties of the nickel foams including yield strength, elastic modulus, energy absorption density and energy absorption efficiency were calculated accurately. The results show that the compressive properties of yield strength, elastic modulus and energy absorption density increase with the increase of relative density of nickel foams. The compressive properties are sensitive to the pre-stretching degree, and the values of yield strength, elastic modulus and energy absorption density decrease with the increase of pre-stretching degree. However, the energy absorption efficiency at the densification strain state exhibits the independence of relative density and pre-stretching degree. The value of energy absorption efficiency reaches its peak when the strain is at the end of the collapse plateau region.
基金supported by the Fundamental Research Funds for the Central Universities of China(No.FRF-BR-15-078A)Beijing Laboratory of Metallic Materials and Processing for Modern Transportation,Specialized Research Fund for the Doctoral Program of Higher Education(No.20120006110019)the Opening Research Fund of the State Key Laboratory for Advanced Metals and Materials(Nos.2012Z-13,2014ZD-02,and 2015-ZD08)
文摘The mechanical properties and constitutive behaviors of as-cast AA7050 in both the solid and semi-solid states were determined using the on-cooling and in situ solidification approaches, respectively. The results show that the strength in the solid state tends to increase with decreasing temperature. The strain rate plays an important role in the stress–strain behaviors at higher temperatures, whereas the influence becomes less pronounced and irregular when the temperature is less than 250°C. The experimental data were fitted to the extended Ludwik equation, which is suitable to describe the mechanical behavior of the materials in the as-cast state. In the semi-solid state, both the strength and ductility of the alloy are high near the solidus temperature and decrease drastically with decreasing solid fraction. As the solid fraction is less than 0.97, the maximum strength only slightly decreases, whereas the post-peak ductility begins to increase. The experimental data were fitted to the modified creep law, which is used to describe the mechanical behavior of semi-solid materials, to determine the equivalent parameter fGBWL, i.e., the fraction of grain boundaries covered by liquid phase.
基金supported by the Natural Science Research Program of Henan Provincial Department of Education (No. 2009A150022)the Young Talented Teacher Foundation of Xinyang Normal University
文摘Geometric structures of 135 polychlorinated fluorene (PCFR) molecules were optimized using density functional theory (DFT) at the B3LYP/6-311G** level and their thermodynamic properties in the ideal gas state were calculated. The relations of these thermodynamic properties with the number and position of chlorine atoms were also explored, from which the relative stability of PCFR congeners was theoretically proposed according to the magnitude of the relative standard Gibbs free energy of formation (Δr,fGθ). The results show that the geometric configuration of PCFR isomers is determined by the position of chlorine atoms. There exist two types of intramolecular weak interactions, i.e., C–H···Cl and Cl···Cl interactions in PCFR molecules. The change of ΔfHθ and ΔfGθ of most stable PCFR isomers with increasing the number of chlorine atoms is different from that in most unstable PCFR congeners. The values of ΔfHθ and ΔfGθ for PCFR isomers with the same number of chlorine atoms strongly depend on the position of chlorine atoms and the relative stability of PCFR congeners is mainly determined by intramolecular delocalized π bond and Cl···Cl nuclear repulsive interaction.
基金Project(LY13E080021) supported by the Natural Science Foundation of Zhejiang Province,ChinaProject(2011A610072) supported by the Ningbo Municipal Natural Science Foundation,ChinaProject(XKL14D2063) supported by Subject Program of Ningbo University,China
文摘To investigate the mechanical properties of cement mortar in sodium sulfate and sodium chloride solutions, uniaxial compression test and ultrasonic test were performed. Test results show that the relative dynamic elastic modulus, the mass variation,and the compressive strength of cement mortar increase first, and then decrease with increasing erosion time in sodium sulfate and sodium chloride solutions. The relative dynamic elastic moduli and the compressive strengths of cement mortars with water/cement ratios of 0.55 and 0.65 in sodium sulfate solution are lower than those in sodium chloride solution with the same concentration at the420 th day of immersion. The compressive strength of cement mortar with water/cement ratio of 0.65 is more sensitive to strain rate than that with water/cement ratio of 0.55. In addition, the strain-rate sensitivity of compressive strength of cement mortar will increase under attacks of sodium sulfate or sodium chloride solution.
基金financially supported by the National Natural Science Foundation of China(No.52174291)。
文摘In order to study the sintering characteristics of Ca-rich iron ore,chemical analysis,laser diffraction,scanning electron microscopy,XRD-Rietveld method,and micro-sintering were used to analyze the mineralogical properties and sintering pot tests were used to study the sintering behavior.In addition,a grey correlation mathematical model was used to calculate and compare the comprehensive sintering performance under different calcium-rich iron ore contents.The results demonstrate that the Ca-rich iron ore has coarse grain size and strong self-fusing characteristics with Ca element in the form of calcite(CaCO_(3)) and the liquid phase produced by the self-fusing of the calcium-rich iron ore is well crystallized.Its application with a 20wt%content in sintering improves sinter productivity,reduces fuel consumption,enhances reduction index,and improves gas permeability in blast furnace by 0.45 t/(m^(2)·h),6.11 kg/t,6.17%,and 65.39 kPa·℃,respectively.The Ca-rich iron ore sintering can improve the calorific value of sintering flue gas compared with magnetite sintering,which is conducive to recovering heat for secondary use.As the content of the Ca-rich iron ore increases,sinter agglomeration shifts from localized liquid-phase bonding to a combination of localized liquid-phase bonding and iron oxide crystal connection.Based on an examination of the greater weight value of productivity with grey correlation analysis,the Ca-rich iron ore is beneficial for the comprehensive index of sintering in the range of 0-20wt%content.Therefore,it may be used in sintering with magnetite concentrates as the major ore species.
基金Supported by the National Natural Science Foundation of China (20977046, 20737001).
文摘The gas phase thermodynamic properties of 135 polychlorinated xanthones(PCXTs)are calculated using a combination of quantum mechanical computations performed with the Gaussian 03 program at the B3LYP/6-311G**level.It is found that the chlorine substitution pattern strongly influences the thermodynamic properties of the compounds.The thermodynamic properties of congeners with the same number of chlorines also depend on the chlorine substitution pattern,especially for ortho-substituted congeners.PCXT congeners with one phenyl ring fully chlorinated are found to be the least stable among the analogues.The effect of the chlorine substitution pattern is quantitatively studied by considering the number and position of Cl atom substitution(NPCS).The results show that the NPCS model may be used to predict the thermodynamic properties for all 135 PCXT congeners. In addition,the values of molar heat capacities at constant pressure(cp,m)from 200 to 1000 K for PCXT congeners are calculated,and the temperature dependence relation of this parameter is obtained using the least-squares method.
文摘Al7075-Cu composite joints were prepared by the squeeze overcast process.The effects of melt temperature,die temperature,and squeeze pressure on hardness and ultimate tensile strength(UTS)of squeeze overcast Al7075-Cu composite joints were studied.The experimental results depict that squeeze pressure is the most significant process parameter affecting the hardness and UTS.The optimal values of UTS(48 MPa)and hardness(76 HRB)are achieved at a melt temperature of 800℃,a die temperature of 250℃,and a squeeze pressure of 90 MPa.Scanning electron microscopy(SEM)shows that fractured surfaces show flatfaced morphology at the optimal experimental condition.Energy-dispersive spectroscopy(EDS)analysis depicts that the atomic weight percentage of Zn decreases with an increase in melt temperature and squeeze pressure.The optimal mechanical properties of the Al7075-Cu overcast joint were achieved at the Al2Cu eutectic phase due to the large number of copper atoms that dispersed into the aluminum melt during the solidification process and the formation of strong intermetallic bonds.Gray relational analysis integrated with the Taguchi method was used to develop an optimal set of control variables for multi-response parametric optimization.Confirmatory tests were performed to validate the effectiveness of the employed technique.The manufacturing of squeeze overcast Al7075-Cu composite joints at optimal process parameters delivers a great indication to acknowledge a new method for foundry practitioners to manufacture materials with superior mechanical properties.
基金China Agriculture Research System(Nos.2019-3-5-1-02,2019-3-4-4,F18R06001-1)China Agriculture Research System of MOF and MARA(No.CARS-30-Z-02)Hebei Province Key Research and Development Project(No.17226341).
文摘Light is crucial to the uniform production of high-quality fruit since it is the driving force for leaf photosynthesis and hence overall plant nutrition.The objective of this study was to evaluate the relationship between the distribution of relative light intensity in the peach tree(Prunus persica)canopy and the yield and texture of peach fruits.The canopy of 7-year-old‘Qiuyan’was divided into cubical volumes and the relative light intensity distribution was measured for each cube,along with yield distribution and fruit textural properties at different growing times.The relative light intensity decreased gradually from outside to inside the canopy and from top to bottom.The yield distribution and the relative light intensity were clearly correlated.The percentage of the canopy receiving<30%relative light intensity was 49.07%in May,56.02%in June,and 58.95%in July,whereas the percentage receiving>80%relative light intensity was 32.72%,17.28%,and 10.96%,respectively.Consistent with this,peaches were found in the upper and middle portions of the canopy,within 1.5-3.0 m of the top.The regression equation showed that fruit texture index correlated significantly with relative light intensity.Relative light intensity is the main factor affecting peach yield and texture and must be above 41.83%for good peach quality.Orchardists should carefully plan summer pruning strategies to adjust the number and spatial distribution of branches accordingly.
文摘Constant weight code is an important error-correcting control code in communications. Basic structure of constant weight codes for some arriving at Johnson bound, A(n, 2u, w), is presented. Some correlative propertys of the codes, the solution of arriving at Johnson bound, and the results on the couple constant code and some constant weight codes are discussed. The conclusion is verified through four examples.
基金supported by Liaoning Doctoral Research Start-up Fund project(Grant No.2023-BS-215).
文摘The relationships between the selective laser melting(SLM)processing parameters including laser power,scanning speed and hatch space,the relative density,the microstructure,and resulting mechanical properties of Ti-6Al-2Zr-1Mo-1V alloy were investigated in this work.The result shows that laser power acts a dominant role in determining the relative density in comparison with scanning speed and hatch space.The optimal SLM process window for fabricating relative density>99%samples is located in the energy density range of 34.72 J·mm^(-3)to 52.08 J·mm^(-3),where the laser power range is between 125 W and 175 W.An upward trend is found in the micro-hardness as the energy density is increased.The optimum SLM processing parameters of Ti-6Al-2Zr-1Mo-1V alloy are:laser power of 150 W,scanning speed of 1,600 mm·s^(-1),hatch space of 0.08 mm,and layer thickness of 0.03 mm.The highest ultimate tensile strength,yield strength,and ductility under the optimum processing parameter are achieved,which are 1,205 MPa,1,099 MPa,and 8%,respectively.The results of this study can be used to guide SLM production Ti-6Al-2Zr-1Mo-1V alloy parts.