The U.S.economy began to grow out of the financial crisis in the second quarter of 2009,the first to get out of the crisis quagmire among western countries.Data indicates its overall economic strength is returning,but...The U.S.economy began to grow out of the financial crisis in the second quarter of 2009,the first to get out of the crisis quagmire among western countries.Data indicates its overall economic strength is returning,but will it resume its traditional dominant pattern in which the financial sector plays a big role?The proportion of the financial service sector within the entire U.S.展开更多
If the U.S.economy is getting better,why can’t ordinary Americans feel it?Given the unemployment and economic statistics being touted of late,shouldn’t voters have more confidence in the president and his party as t...If the U.S.economy is getting better,why can’t ordinary Americans feel it?Given the unemployment and economic statistics being touted of late,shouldn’t voters have more confidence in the president and his party as the November 2016 general elections loom?Even in 2014 as the country grew further away from recession lows,outshining economies in most展开更多
Pyrolysis of biomass followed by combustion of pyrolytic vapors to replace fossil fuels is an economic low-carbon solution.However,the polycyclic aromatic hydrocarbons and N-containing species in biomass pyrolysis vap...Pyrolysis of biomass followed by combustion of pyrolytic vapors to replace fossil fuels is an economic low-carbon solution.However,the polycyclic aromatic hydrocarbons and N-containing species in biomass pyrolysis vapors result in the soot and NO emissions.The flue gas recirculation(FGR)technology,having the potential to reduce the soot and NO emissions,was introduced to the biomass pyrolysis-combustion system.In addition,it was numerically studied by simulating the biomass pyrolysis vapors based co-flow diffusion flames with CO_(2)addition.Both the experimental and simulated results showed that the FGR had significant suppression effects on the soot formation.When the FGR ratio(i.e.,CO_(2)addition ratio)increased from 0%to 15%,the experimental and simulated soot volume fraction respectively decreased by 32%and 21%,which verified the models used in this study.The decrease in OH concentration caused by the CO_(2)addition was responsible for the decrease in the decomposition rate of A2(A2+OH=A2–+H_(2)O).Hence,more benzo(ghi)fluoranthene(BGHIF)was generated through A1C_(2)H–+A2→BGHIF+H_(2)+H,leading to the increase in inception rate.The decrease in benzo(a)pyrene(BAPYR)concentration was the major factor in the decrease in soot condensation rate.Moreover,the decrease in the C_(2)H_(2) and OH concentrations was responsible for the decrease in the HACA surface growth rate.Furthermore,the simulated results showed that the NO concentration decreased by 0.4%when the content of CO_(2)was increased by 1 vol.%.The decrease in OH concentration suppressed the NO formation via decreasing reaction rates of N+OH=NO+H and HNO+OH=NO+H_(2)O and enhanced the NO consumption via increasing reaction rate of HO_(2)+NO=NO_(2)+OH.展开更多
In 1997 and 1998, hundreds of specimens of megascopic carbonaceous compressions or algal fossils were found from - 1800-million-year old Changzhougou Formation, which is the lowermost unit of the latest Palaeoproteroz...In 1997 and 1998, hundreds of specimens of megascopic carbonaceous compressions or algal fossils were found from - 1800-million-year old Changzhougou Formation, which is the lowermost unit of the latest Palaeoproterozoic Changcheng Group (~1 600-1 800 Ma) in the Xinglong-Kuancheng areas at the middle Yanshan Range, North China. They are discoid, ellipsoid and sausage-like, namely shaped like Chuaria Shouhsiennia (Ellipsophyta) and Tawuia. By adopting HF acid-resistant maceration coupled with scanning electron microscope and petrologic section, the authors made a preliminary research on the histology for some circular and ellipsoid carbonaceous compressions, namely Chuaria- and Shouhsienia-llke forms, in addition to their morphology. The following three types of multicellular tissues have been found in the fragments of them: colony-like, pseudoparenchyma-like and parenchyma-like. All of the new data about multicelluar tissues not only supply a very important basis in histology to determine the展开更多
文摘The U.S.economy began to grow out of the financial crisis in the second quarter of 2009,the first to get out of the crisis quagmire among western countries.Data indicates its overall economic strength is returning,but will it resume its traditional dominant pattern in which the financial sector plays a big role?The proportion of the financial service sector within the entire U.S.
文摘If the U.S.economy is getting better,why can’t ordinary Americans feel it?Given the unemployment and economic statistics being touted of late,shouldn’t voters have more confidence in the president and his party as the November 2016 general elections loom?Even in 2014 as the country grew further away from recession lows,outshining economies in most
基金supported by the National Natural Science Foundation of China(Grant Nos.52276185,52276189,and 51976057)the Science and Technology Innovation Program of Hunan Province(Grant No.2020RC5008)the Fundamental Research Funds for the Central Universities(Grant No.2020DF01)。
文摘Pyrolysis of biomass followed by combustion of pyrolytic vapors to replace fossil fuels is an economic low-carbon solution.However,the polycyclic aromatic hydrocarbons and N-containing species in biomass pyrolysis vapors result in the soot and NO emissions.The flue gas recirculation(FGR)technology,having the potential to reduce the soot and NO emissions,was introduced to the biomass pyrolysis-combustion system.In addition,it was numerically studied by simulating the biomass pyrolysis vapors based co-flow diffusion flames with CO_(2)addition.Both the experimental and simulated results showed that the FGR had significant suppression effects on the soot formation.When the FGR ratio(i.e.,CO_(2)addition ratio)increased from 0%to 15%,the experimental and simulated soot volume fraction respectively decreased by 32%and 21%,which verified the models used in this study.The decrease in OH concentration caused by the CO_(2)addition was responsible for the decrease in the decomposition rate of A2(A2+OH=A2–+H_(2)O).Hence,more benzo(ghi)fluoranthene(BGHIF)was generated through A1C_(2)H–+A2→BGHIF+H_(2)+H,leading to the increase in inception rate.The decrease in benzo(a)pyrene(BAPYR)concentration was the major factor in the decrease in soot condensation rate.Moreover,the decrease in the C_(2)H_(2) and OH concentrations was responsible for the decrease in the HACA surface growth rate.Furthermore,the simulated results showed that the NO concentration decreased by 0.4%when the content of CO_(2)was increased by 1 vol.%.The decrease in OH concentration suppressed the NO formation via decreasing reaction rates of N+OH=NO+H and HNO+OH=NO+H_(2)O and enhanced the NO consumption via increasing reaction rate of HO_(2)+NO=NO_(2)+OH.
文摘In 1997 and 1998, hundreds of specimens of megascopic carbonaceous compressions or algal fossils were found from - 1800-million-year old Changzhougou Formation, which is the lowermost unit of the latest Palaeoproterozoic Changcheng Group (~1 600-1 800 Ma) in the Xinglong-Kuancheng areas at the middle Yanshan Range, North China. They are discoid, ellipsoid and sausage-like, namely shaped like Chuaria Shouhsiennia (Ellipsophyta) and Tawuia. By adopting HF acid-resistant maceration coupled with scanning electron microscope and petrologic section, the authors made a preliminary research on the histology for some circular and ellipsoid carbonaceous compressions, namely Chuaria- and Shouhsienia-llke forms, in addition to their morphology. The following three types of multicellular tissues have been found in the fragments of them: colony-like, pseudoparenchyma-like and parenchyma-like. All of the new data about multicelluar tissues not only supply a very important basis in histology to determine the
