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排序方式: 共有476条查询结果,搜索用时 31 毫秒
1.
The Er3+ doped oxyfluorogermanate glasses, with a composition containing Na element, were synthesized by the conventional melting–quenching technique. When Na element was introduced into the composition of oxyfluorogermanate glass, the crystals behavior was investigated in details. Depending on the annealing procedure supplied, thermal annealing of precursor glasses in the system GeO2/BaF2/AlF3/Na2O/NaF/ZnO/GdF3/ErF3 led to the precipitation of different crystal phase nanocrystals. It was confirmed the nanocrystals in GC600 is orthorhombic NaBaAlF6 which led to enhance obviously in the UC luminescence of Er3+. However, the nanocrystals in G585 led to decrease in the UC luminescence, which indicated few Er ions enter into the lattice of this nanocrystal phase. The reason of the decrease in UC emission intensity of GC585 was analyzed. 相似文献
2.
Results of calorimetric investigations performed on two groups of glasses, viz. As-Te-Se and Ge-As-Se, are described. The
glass transition temperatureT
g and specific heat at constant pressureC
p
of these two families of glasses have been determined using a differential scanning calorimeter. The composition dependence
of glass transition temperature and variation of heat capacity during transition are discussed. 相似文献
3.
ZnS, ZnSe, and CdTe polycrystals are experimentally investigated. Mechanisms are treated which restrict the thermal conductivity in samples prepared by recrystallization pressing and by deposition from the vapor phase and subjected to additional strain. Anomalies are observed on the temperature dependences of the thermal resistance of investigated samples, which are due to the special features of their phonon spectra and to the variation of the contribution made by longitudinal and transverse phonon branches to the heat transfer in the Debye temperature region and higher. 相似文献
4.
The space-time distribution of the basic kinetic parameters of a plasma is experimentally determined under conditions of expansion of plasma clusters and jets into vacuum. It is demonstrated that the dynamics and structure of plasmoids injected by pulsed erosion plasma accelerators of the electrothermal type are characterized by two successive stages or two modes of acceleration, namely, the Joule heating of electrons in the initial region of the path and the collisionless expansion of rarefied plasma. 相似文献
5.
M. A. Fatykhov 《High Temperature》2004,42(4):621-628
The paper gives the results of experimental investigations of the initial pressure gradient of bituminous oil and the time dependences of variation of the temperature in a formation model and of the well production rate in a microwave-frequency electromagnetic field. The effect of strong decay of the non-Newtonian properties of bituminous oil is revealed. The nonuniformity of temperature distribution over the formation thickness is demonstrated, which depends on the initial production rate of the well and on the duration of stimulation of the bottom-hole zone of formation. 相似文献
6.
红外窗口的激光损伤热过程及保护的研究 总被引:1,自引:1,他引:0
利用光热偏转技术对红外窗口材料进行了激光损伤实时研究,通过对硅片,加半反保护膜的硅片和加全反保护膜的硅片的损伤过程的研究,发现介质保护膜能大大提高硅窗口的激光损伤阈值,同时发现了全反介质保护膜的激光损伤逐层的破坏过程。 相似文献
7.
Geotechnical characterization of potential lunar sites will be a critical part of the planning and design process. The strategies used to conduct a geotechnical investigation will be dictated by the specific needs of the lunar base, the unique environment of the lunar surface, and general character of the lunar soils and rocks. This paper outlines some of the types of geotechnical information that will be important and identifies some of the more promising strategies which might be used to obtain such information in the lunar environment. Some of the most important geotechnical information for planning and site development will be related to construction in the lunar soil. In addition to construction concerns, geotechnical data for foundation design (or verification of predesigned foundations) will be needed. The geotechnical site‐characterization work should include geophysical techniques, supplemented by conventional mechanical boring and testing only to the degree necessary to correlate geophysical measurements with conventional soil properties and to investigate anomalies. Equipment used for geotechnical site characterization will also serve for mineralogical exploration. Several techniques for geotechnical investigation that may provide very useful information in an expedient manner are described. Geophysical methods include seismic and electromagnetic methods, including seismic surveys that utilize surface waves. Electromagnetic methods such as ground‐penetrating radar are fast, efficient methods for mapping the subsurface, although these techniques do not measure soil characteristics that can readily be correlated with engineering properties. Seismic methods provide information that may correlate with soil strength, compressibility, and excavatability. In‐situ physical testing will likely include penetration testing for direct physical measurement of lunar soil behavior. 相似文献
8.
9.
A. NabokAuthor Vitae A. TsargorodskayaAuthor VitaeM.K. MustafaAuthor Vitae I. SzékácsAuthor Vitae N.F. StarodubAuthor VitaeA. SzékácsAuthor Vitae 《Sensors and actuators. B, Chemical》2011,154(2):232-237
The method of total internal reflection ellipsometry (TIRE), which records simultaneously two parameters Δ and Ψ related to the amplitudes and phases of p- and s-components of polarised light, respectively, was exploited here for detection of mycotoxins (T-2 and zearalenone). The above mycotoxins in sub-ppb concentrations were detected using TIRE in both direct and competitive immunoassay. The study of immune reaction kinetics allowed the evaluation of adsorption/desorption rates and the association constant for zearalenone. The investigation of grain products samples revealed the presence of high concentrations of T-2 (>600 ng/ml) in mould products. 相似文献
10.
This paper presents a method for the field measurement of airtightness for two-?and three-unit buildings using only one fan pressurization system, commonly referred to as a blower door. The main advantage of this single-fan method is its lower equipment and labor cost as compared with multiple-fan methods. Results from consecutive tests in the individual units are used to prepare a set of simultaneous equations for airflow, allowing for the calculation of the air leakage characteristics of both the interior partitions and the exterior envelope on a unit-per-unit basis. Tests were performed on four buildings using the single-fan method and were compared with those obtained with a two-fan method. Test results indicate that the single-fan method may be of value as an inexpensive method of estimating the airtightness of two-?and three-unit residential buildings. 相似文献