The Moon,as the closest celestial body to the Earth,plays a pivotal role in the progression of deep space exploration,and the establishment of research outposts on its surface represents a crucial step in this mission...The Moon,as the closest celestial body to the Earth,plays a pivotal role in the progression of deep space exploration,and the establishment of research outposts on its surface represents a crucial step in this mission.Lunar lava tubes are special underground caves formed by volcanic eruptions and are considered as ideal natural shelters and scientific laboratories for lunar base construction.This paper begins with an in-depth overview of the geological origins,exploration history,and distribution locations of lunar lava tubes.Subsequently,it delves into the presentation of four distinctive advantages and typical concepts for constructing bases within lava tubes,summarizing the ground-based attempts made thus far in lunar lava tube base construction.Field studies conducted on a lava tube in Hainan revealed rock compositions similar to those found during the Apollo missions and clear lava tube structures,making it a promising analog site.Lastly,the challenges and opportunities encountered in the field of geotechnical engineering regarding the establishment of lunar lava tube bases are discussed,encompassing cave exploration technologies,in-situ testing methods,geomechanical properties under lunar extreme environments,base design and structural stability assessment,excavation and reinforcement techniques,and simulated Earth-based lava tube base.展开更多
The scientific evaluation on heat insulation and preservation capacity of rammed earth construction can provide an effective evidence for its superiority in preserving thermal environment of the construction. By takin...The scientific evaluation on heat insulation and preservation capacity of rammed earth construction can provide an effective evidence for its superiority in preserving thermal environment of the construction. By taking an eco-hotel in Zhejiang Anji County as the research object, 33 test points have been set. The indoor and outdoor air temperature of eco-hotel and the surface temperature of building envelopes had been recorded by using data acquisition instrument, temperature transmitter and other equipments from January 27 to February 2 in 2007. Then, the data of a period had been selected for comparison and analysis and the results had been obtained as follows. In January when the temperature difference between day and night in Anji was not large, without particular thermal insulation measures and equipments, the indoor temperature of eco-hotel fluctuated very little, showing that rammed earth construction was of obvious capacity for heat preservation and insulation, that its heat stability was evident and that it could ensure excellent indoor thermal environment.展开更多
In this study,the Beibu earth fissure site in the northeastern part of Weihe Basin,which contains four nearly parallel earth fissures,was studied.A long straight microtremor measuring line,containing 49 measuring poin...In this study,the Beibu earth fissure site in the northeastern part of Weihe Basin,which contains four nearly parallel earth fissures,was studied.A long straight microtremor measuring line,containing 49 measuring points across four earth fissures,was established to investigate the dynamic response of this site using Fourier spectrum,response acceleration spectrum,Arias intensity,and HVSR analyses.The main results are as follows:(1)The fundamental frequencies of 44 measuring points obtained from HVSR analysis are concentrated within 1.67 Hz-2.25 Hz,and the existence of the earth fissures has little effect on the fundamental frequency changes.(2)There is an amplification effect near a single earth fissure.The dynamic responses are large at the measuring points near the earth fissure,and the values decrease with increasing distance from the earth fissure.In areas between two adjacent earth fissures,these values decrease and are even lower than those in sites without amplification effects.(3)In this earth fissure site,the general area(or less affected area)and affected areas were delineated based on the amplification effect.In engineering applications,construction design should avoid these affected areas and existing structures should be reinforced to satisfy the seismic fortification requirements.展开更多
The Curie temperature of(Nd_(1-x)Pr_x)_2Fe_(14)Co_yB compounds(x=0,0.2,…,1.0 and y=O,2,4,6,14)has been determined with AC initial susceptibility measurement.It was found that the variations of Curie tempera- ture wit...The Curie temperature of(Nd_(1-x)Pr_x)_2Fe_(14)Co_yB compounds(x=0,0.2,…,1.0 and y=O,2,4,6,14)has been determined with AC initial susceptibility measurement.It was found that the variations of Curie tempera- ture with x is not linear for y=0 and 14,whereas it is linear for other values of y.The lattice constants of (Nd_(1-x)Pr_x)_2Fet_(14)B were determined by using X-ray diffraction.The lattice expansion was mostly along the c axis,whereas that along the a-axis remained practically zero for the whole series.It is suggested that Pr atoms may show site preference in R_2M_(14)B compounds(M=Fe or Co).Due to the substitution of Co for Fe.the tendency of site preference of Pr becomes less pronounced,which may be attributed to the decrease of differ- ence of crystal electric field(CEF)acting on the two rare earth sites with the introduction of Co or Fe.In con- trast to that of the Pr atoms,the site preference of Co iu(Nd(1-x)Pr_x)_2Fe(14-y)Co_yB compounds does not depend on the composition of the rare earth sublattice(R=N d or Pr).展开更多
The phase stability and site preference of the intermetallics LaFe13-xTx (T=Cr, Cu, Ga, Mn, Ni) with NaZn13-type structure have been investigated by lattice inversion potentials. The calculated results indicate that e...The phase stability and site preference of the intermetallics LaFe13-xTx (T=Cr, Cu, Ga, Mn, Ni) with NaZn13-type structure have been investigated by lattice inversion potentials. The calculated results indicate that each of the stabilizing elements Cr and Mn significantly decreases the cohesive energy of LaFe13-xTx and plays a role in stabilizing the 1:13 structure. The calculated lattice parameters of LaFe13-xTx (T=Al, Si) compounds are in good agreement with the experimental data. Qualitative analyses are carried out on the behavior of the Curie temperature and magnetocrystalline anisotropy. All the results indicate that the pair potentials based on the lattice inversion method can effectively give a deeper insight into the structure and property of complex materials.展开更多
By using a whitelight lamp, an Ar+ ion laser whosewavelength was tuned to 457. 9 nmand a tunable Rh 6G dye laser(linewidth: 0. 5 cm-1) pumped bythe second harmonic of a Nd: YAGlaser as light sources and using amonochr...By using a whitelight lamp, an Ar+ ion laser whosewavelength was tuned to 457. 9 nmand a tunable Rh 6G dye laser(linewidth: 0. 5 cm-1) pumped bythe second harmonic of a Nd: YAGlaser as light sources and using amonochromator, a phase-lockingamplifier and a computer as the data detecting system, the transmission spectrum, fluorescence spectra, excitation spectrum and siteselective fluorescence spectra ofthe Eu3+: Y2SiO5 crystal were observed. More than thirty out of thetotal fifty spectral lines were observed for 5D0→7F0,1,2,3,4 transitions. The Eu3+ ions occupy twokinds of the Y3+ sites with the lowsymmetry in this crystal. The difference of the wavelengths of thetwo Eu3+ sites for 7F0→5D0 transition is about 0. 2 nm. It was foundthat the two sites were nonequivalent optical ones at room temperature. Crystal lattice constants a,b, c, and β of Eu3+: Y2SiO5 werealso measured by the X-ray diffraction method. The results show thatthe lattice constants a, b, and cof the crystal doped Eu3+ ions isvery close to those of the Y2SiO5crystal undoped Eu3+ ions.展开更多
It was observed that rare earth ions (Nd 3+, Sm 3+, Eu 3+, Gd 3+, Tb 3+) have significant quenching effects on the fluorescence of anticoagulation factor I (ACF I). The results of the fluorescence titra...It was observed that rare earth ions (Nd 3+, Sm 3+, Eu 3+, Gd 3+, Tb 3+) have significant quenching effects on the fluorescence of anticoagulation factor I (ACF I). The results of the fluorescence titration of ACF I with rare earth ions demonstrate that ACF I has two RE 3+-binding sites, and the rare earth ions and Ca 2+ bind to ACF I competitively in the two similar sites. The association constants K 1 and K 2 of ACF I with each rare earth ions (Nd 3+, Sm 3+, Eu 3+, Gd 3+, Tb 3+) are close to each other, which indicates the structural similarity of the two binding sites in ACF I. Although the ionic radii of Nd 3+, Sm 3+, Eu 3+, Gd 3+ and Tb 3+ are different, both their K 1 and K 2 are similar, respectively. This reveals the conformational flexibility of the two binding sites in ACF I, which offers a possibility for Ca 2+ to take play in the inducing conformational changes of ACF I and the promoting the binding of ACF I with activated coagulation factor X.展开更多
基金supported by the National Natural Science Foundation of China(Nos.52125903 and 52339001).
文摘The Moon,as the closest celestial body to the Earth,plays a pivotal role in the progression of deep space exploration,and the establishment of research outposts on its surface represents a crucial step in this mission.Lunar lava tubes are special underground caves formed by volcanic eruptions and are considered as ideal natural shelters and scientific laboratories for lunar base construction.This paper begins with an in-depth overview of the geological origins,exploration history,and distribution locations of lunar lava tubes.Subsequently,it delves into the presentation of four distinctive advantages and typical concepts for constructing bases within lava tubes,summarizing the ground-based attempts made thus far in lunar lava tube base construction.Field studies conducted on a lava tube in Hainan revealed rock compositions similar to those found during the Apollo missions and clear lava tube structures,making it a promising analog site.Lastly,the challenges and opportunities encountered in the field of geotechnical engineering regarding the establishment of lunar lava tube bases are discussed,encompassing cave exploration technologies,in-situ testing methods,geomechanical properties under lunar extreme environments,base design and structural stability assessment,excavation and reinforcement techniques,and simulated Earth-based lava tube base.
基金Supported by Fund of Key Scientific and Technological Project of Henan Province (10210210080)Henan Government Decision-making Research Bidding Project (2011B706)~~
文摘The scientific evaluation on heat insulation and preservation capacity of rammed earth construction can provide an effective evidence for its superiority in preserving thermal environment of the construction. By taking an eco-hotel in Zhejiang Anji County as the research object, 33 test points have been set. The indoor and outdoor air temperature of eco-hotel and the surface temperature of building envelopes had been recorded by using data acquisition instrument, temperature transmitter and other equipments from January 27 to February 2 in 2007. Then, the data of a period had been selected for comparison and analysis and the results had been obtained as follows. In January when the temperature difference between day and night in Anji was not large, without particular thermal insulation measures and equipments, the indoor temperature of eco-hotel fluctuated very little, showing that rammed earth construction was of obvious capacity for heat preservation and insulation, that its heat stability was evident and that it could ensure excellent indoor thermal environment.
基金National Natural Science Foundation of China under Grant No.41772275the Fundamental Research Funds for the Central Universities under Grant No.CHD300102268203。
文摘In this study,the Beibu earth fissure site in the northeastern part of Weihe Basin,which contains four nearly parallel earth fissures,was studied.A long straight microtremor measuring line,containing 49 measuring points across four earth fissures,was established to investigate the dynamic response of this site using Fourier spectrum,response acceleration spectrum,Arias intensity,and HVSR analyses.The main results are as follows:(1)The fundamental frequencies of 44 measuring points obtained from HVSR analysis are concentrated within 1.67 Hz-2.25 Hz,and the existence of the earth fissures has little effect on the fundamental frequency changes.(2)There is an amplification effect near a single earth fissure.The dynamic responses are large at the measuring points near the earth fissure,and the values decrease with increasing distance from the earth fissure.In areas between two adjacent earth fissures,these values decrease and are even lower than those in sites without amplification effects.(3)In this earth fissure site,the general area(or less affected area)and affected areas were delineated based on the amplification effect.In engineering applications,construction design should avoid these affected areas and existing structures should be reinforced to satisfy the seismic fortification requirements.
基金This work was partly supported by National Science Foundation(No.5870025)Magnetism Laboratory,Institute of Physics,Academia Sinica,Bejing,P.R.China.
文摘The Curie temperature of(Nd_(1-x)Pr_x)_2Fe_(14)Co_yB compounds(x=0,0.2,…,1.0 and y=O,2,4,6,14)has been determined with AC initial susceptibility measurement.It was found that the variations of Curie tempera- ture with x is not linear for y=0 and 14,whereas it is linear for other values of y.The lattice constants of (Nd_(1-x)Pr_x)_2Fet_(14)B were determined by using X-ray diffraction.The lattice expansion was mostly along the c axis,whereas that along the a-axis remained practically zero for the whole series.It is suggested that Pr atoms may show site preference in R_2M_(14)B compounds(M=Fe or Co).Due to the substitution of Co for Fe.the tendency of site preference of Pr becomes less pronounced,which may be attributed to the decrease of differ- ence of crystal electric field(CEF)acting on the two rare earth sites with the introduction of Co or Fe.In con- trast to that of the Pr atoms,the site preference of Co iu(Nd(1-x)Pr_x)_2Fe(14-y)Co_yB compounds does not depend on the composition of the rare earth sublattice(R=N d or Pr).
文摘The phase stability and site preference of the intermetallics LaFe13-xTx (T=Cr, Cu, Ga, Mn, Ni) with NaZn13-type structure have been investigated by lattice inversion potentials. The calculated results indicate that each of the stabilizing elements Cr and Mn significantly decreases the cohesive energy of LaFe13-xTx and plays a role in stabilizing the 1:13 structure. The calculated lattice parameters of LaFe13-xTx (T=Al, Si) compounds are in good agreement with the experimental data. Qualitative analyses are carried out on the behavior of the Curie temperature and magnetocrystalline anisotropy. All the results indicate that the pair potentials based on the lattice inversion method can effectively give a deeper insight into the structure and property of complex materials.
文摘By using a whitelight lamp, an Ar+ ion laser whosewavelength was tuned to 457. 9 nmand a tunable Rh 6G dye laser(linewidth: 0. 5 cm-1) pumped bythe second harmonic of a Nd: YAGlaser as light sources and using amonochromator, a phase-lockingamplifier and a computer as the data detecting system, the transmission spectrum, fluorescence spectra, excitation spectrum and siteselective fluorescence spectra ofthe Eu3+: Y2SiO5 crystal were observed. More than thirty out of thetotal fifty spectral lines were observed for 5D0→7F0,1,2,3,4 transitions. The Eu3+ ions occupy twokinds of the Y3+ sites with the lowsymmetry in this crystal. The difference of the wavelengths of thetwo Eu3+ sites for 7F0→5D0 transition is about 0. 2 nm. It was foundthat the two sites were nonequivalent optical ones at room temperature. Crystal lattice constants a,b, c, and β of Eu3+: Y2SiO5 werealso measured by the X-ray diffraction method. The results show thatthe lattice constants a, b, and cof the crystal doped Eu3+ ions isvery close to those of the Y2SiO5crystal undoped Eu3+ ions.
文摘It was observed that rare earth ions (Nd 3+, Sm 3+, Eu 3+, Gd 3+, Tb 3+) have significant quenching effects on the fluorescence of anticoagulation factor I (ACF I). The results of the fluorescence titration of ACF I with rare earth ions demonstrate that ACF I has two RE 3+-binding sites, and the rare earth ions and Ca 2+ bind to ACF I competitively in the two similar sites. The association constants K 1 and K 2 of ACF I with each rare earth ions (Nd 3+, Sm 3+, Eu 3+, Gd 3+, Tb 3+) are close to each other, which indicates the structural similarity of the two binding sites in ACF I. Although the ionic radii of Nd 3+, Sm 3+, Eu 3+, Gd 3+ and Tb 3+ are different, both their K 1 and K 2 are similar, respectively. This reveals the conformational flexibility of the two binding sites in ACF I, which offers a possibility for Ca 2+ to take play in the inducing conformational changes of ACF I and the promoting the binding of ACF I with activated coagulation factor X.
