The crystal Nd 3+∶Sr 6YSc(BO 3) 6 was grown by the top-seeded solution growth method from a Li 6B 4O 9 flux. The s pectral properties of Nd 3+∶Sr 6YSc(BO 3) 6 crystal were investigated. Using Judd-Ofel...The crystal Nd 3+∶Sr 6YSc(BO 3) 6 was grown by the top-seeded solution growth method from a Li 6B 4O 9 flux. The s pectral properties of Nd 3+∶Sr 6YSc(BO 3) 6 crystal were investigated. Using Judd-Ofelt theory to ana lyze the optical strength measured in absorption spectrum, the following spectr al parameters were obtained: parameters of oscillator strengths Ω λ are Ω 2=1.194×10 -20 cm2, Ω 4=4.186×10 -20 cm2 and Ω 6=3.3 51×10 -20 cm2. The radiative lifetime is 322 μs, and the fluorescence b ranch ratios were calculated: β 1=0.465, β 2=0.453, β 3=0.079 and β 4=0.004. The results indicate that Nd 3+∶Sr 6YSc(BO 3) 6 c rystal seems to be a potential high-efficient laser material.展开更多
[Objective] This study aimed to estimate the genetic parameters for milk yield, fat percentage, fat yield and age at first freshening of Chinese Holsteins first lactation cows in Heilongjiang under frigid-temperature ...[Objective] This study aimed to estimate the genetic parameters for milk yield, fat percentage, fat yield and age at first freshening of Chinese Holsteins first lactation cows in Heilongjiang under frigid-temperature and temperature zone. [Method] Records of yield and reproduction from 8 868 Chinese Holstein first lacta- tion cows from 21 herds were utilized to evaluate genetic parameters for Hei- Iongjiangs＇ Chinese Holsteins. Restricted maximum likelihood （REML） method was used with an animal model. [Result] The heritabilities were 0.16 to 0.34 for yields and fat percentage, 0.38 for reproduction （age at the first freshening）, which were similar to estimates for temperate areas from similar methods, except for constituent percentage. Also, the estimates of genetic correlation were high between milk yield and fat yield （0.97）, but were low between milk yield and fat percentage （-0.24）, age at the first freshening （-0.29） and generally antagonistic. [Conclusion] Thus, es- timates of genetic parameters in this frigid and frigid-temperate environment did not differ appreciably from those that occur in temperate dairy areas.展开更多
The influence of the structure parameters on the characteristics of dynamic mixer with striped channels is studied. As results indicate that, given the proper structure parameters, the output of the extruder can be in...The influence of the structure parameters on the characteristics of dynamic mixer with striped channels is studied. As results indicate that, given the proper structure parameters, the output of the extruder can be increased with low energy consumption and stable temperature. Furthermore, the mixing effect will be improved up to or even above that of spherical cavity mixer.展开更多
In the pastfew years,severalnew melting processeshavebeenindustrialised forthe produc tion ofsuperalloys,titanium alloysand high qualitysteelsfor useintheaero engineindustry.Theseincludeelectron beam , plasma,indu...In the pastfew years,severalnew melting processeshavebeenindustrialised forthe produc tion ofsuperalloys,titanium alloysand high qualitysteelsfor useintheaero engineindustry.Theseincludeelectron beam , plasma,inductionskull,andthe”triple melt”process( VIM + ESR+ VAR) . These developments have allbeen instituted in responsetothe major per ceived problem oftheindustry ;that oftheincidence of random defectsin the alloys whichcause problemsinregardto predictablelifing ofthefinished partinservice. Thedirectconse quenceofthe uncertaintyislossof revenue due to premature retirement of parts which mayhavecompleted on a fraction oftheir actualservicelife; a conservatism on the partof design parameters whichleadsto uneccesary weightin thepart;and ariskofeitherservicefailuresor partrecalls whichinterruptengine performance. Thebenefitsoftheprocesschangesinrespectoftheproducts’absolute propertiesand alsoonthereproducibility and inspectability ofthose properties have been substantial. Itisclearthattheprocesses offer the industry a solution to the present dilem ma of how to treatthe ”rare”defectsfrom the pointof view of fracture mechanicslifing methodology. The use ofprocesscontrols which guarantee”zero defect”productisdevelopingintoacriticaltoolfortheextension oftherangeof a given alloy’s use. Itislikelyto permit very substantial gainsinboth componentlife and intheallowablestressin rotating parts withoutthe needtointroduce new materials carrying new problems of user confidence, production reliability and data base. Weconcludethatthenew processesareatastageof development wherethey arereadyforwideindustry usein production. They will not add significantly tothecomponentcost andthey willgive a renwed lifespan to the more familiar materials and methodsof aero engineconstruction.展开更多
The 3-D velocity tomography image of the central-eastern part of Qilianshan is obtained by the joint inversion of 3-D velocity structure and focal parameters based on the S-P data of micro-earthquakes recorded by the ...The 3-D velocity tomography image of the central-eastern part of Qilianshan is obtained by the joint inversion of 3-D velocity structure and focal parameters based on the S-P data of micro-earthquakes recorded by the digital seismic network set up for a Sino-French cooperation program since 1996. The inversed velocity structure does primarily reflect some important features of the deep structure in the region and provide the scientific background for the further study of active tectonic structure and the calculation of earthquake parameters.展开更多
文摘The crystal Nd 3+∶Sr 6YSc(BO 3) 6 was grown by the top-seeded solution growth method from a Li 6B 4O 9 flux. The s pectral properties of Nd 3+∶Sr 6YSc(BO 3) 6 crystal were investigated. Using Judd-Ofelt theory to ana lyze the optical strength measured in absorption spectrum, the following spectr al parameters were obtained: parameters of oscillator strengths Ω λ are Ω 2=1.194×10 -20 cm2, Ω 4=4.186×10 -20 cm2 and Ω 6=3.3 51×10 -20 cm2. The radiative lifetime is 322 μs, and the fluorescence b ranch ratios were calculated: β 1=0.465, β 2=0.453, β 3=0.079 and β 4=0.004. The results indicate that Nd 3+∶Sr 6YSc(BO 3) 6 c rystal seems to be a potential high-efficient laser material.
文摘[Objective] This study aimed to estimate the genetic parameters for milk yield, fat percentage, fat yield and age at first freshening of Chinese Holsteins first lactation cows in Heilongjiang under frigid-temperature and temperature zone. [Method] Records of yield and reproduction from 8 868 Chinese Holstein first lacta- tion cows from 21 herds were utilized to evaluate genetic parameters for Hei- Iongjiangs＇ Chinese Holsteins. Restricted maximum likelihood （REML） method was used with an animal model. [Result] The heritabilities were 0.16 to 0.34 for yields and fat percentage, 0.38 for reproduction （age at the first freshening）, which were similar to estimates for temperate areas from similar methods, except for constituent percentage. Also, the estimates of genetic correlation were high between milk yield and fat yield （0.97）, but were low between milk yield and fat percentage （-0.24）, age at the first freshening （-0.29） and generally antagonistic. [Conclusion] Thus, es- timates of genetic parameters in this frigid and frigid-temperate environment did not differ appreciably from those that occur in temperate dairy areas.
文摘The influence of the structure parameters on the characteristics of dynamic mixer with striped channels is studied. As results indicate that, given the proper structure parameters, the output of the extruder can be increased with low energy consumption and stable temperature. Furthermore, the mixing effect will be improved up to or even above that of spherical cavity mixer.
文摘In the pastfew years,severalnew melting processeshavebeenindustrialised forthe produc tion ofsuperalloys,titanium alloysand high qualitysteelsfor useintheaero engineindustry.Theseincludeelectron beam , plasma,inductionskull,andthe”triple melt”process( VIM + ESR+ VAR) . These developments have allbeen instituted in responsetothe major per ceived problem oftheindustry ;that oftheincidence of random defectsin the alloys whichcause problemsinregardto predictablelifing ofthefinished partinservice. Thedirectconse quenceofthe uncertaintyislossof revenue due to premature retirement of parts which mayhavecompleted on a fraction oftheir actualservicelife; a conservatism on the partof design parameters whichleadsto uneccesary weightin thepart;and ariskofeitherservicefailuresor partrecalls whichinterruptengine performance. Thebenefitsoftheprocesschangesinrespectoftheproducts’absolute propertiesand alsoonthereproducibility and inspectability ofthose properties have been substantial. Itisclearthattheprocesses offer the industry a solution to the present dilem ma of how to treatthe ”rare”defectsfrom the pointof view of fracture mechanicslifing methodology. The use ofprocesscontrols which guarantee”zero defect”productisdevelopingintoacriticaltoolfortheextension oftherangeof a given alloy’s use. Itislikelyto permit very substantial gainsinboth componentlife and intheallowablestressin rotating parts withoutthe needtointroduce new materials carrying new problems of user confidence, production reliability and data base. Weconcludethatthenew processesareatastageof development wherethey arereadyforwideindustry usein production. They will not add significantly tothecomponentcost andthey willgive a renwed lifespan to the more familiar materials and methodsof aero engineconstruction.
基金National Natural Science Foundation of China (40074010) and Natural Science Foundation of Gansu Province(ZS981-A25-011).
文摘The 3-D velocity tomography image of the central-eastern part of Qilianshan is obtained by the joint inversion of 3-D velocity structure and focal parameters based on the S-P data of micro-earthquakes recorded by the digital seismic network set up for a Sino-French cooperation program since 1996. The inversed velocity structure does primarily reflect some important features of the deep structure in the region and provide the scientific background for the further study of active tectonic structure and the calculation of earthquake parameters.
