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51.
52.
Giorgio Benedek Joseph R. Manson Salvador Miret-Artés 《Advanced materials (Deerfield Beach, Fla.)》2020,32(25):2002072
Atom scattering is becoming recognized as a sensitive probe of the electron–phonon interaction parameter λ at metal and metal-overlayer surfaces. Here, the theory is developed, linking λ to the thermal attenuation of atom scattering spectra (in particular, the Debye–Waller factor), to conducting materials of different dimensions, from quasi-1D systems such as W(110):H(1 × 1) and Bi(114), to quasi-2D layered chalcogenides, and high-dimensional surfaces such as quasicrystalline 2ML-Ba(0001)/Cu(001) and d-AlNiCo(00001). Values of λ obtained using He atoms compare favorably with known values for the bulk materials. The corresponding analysis indicates in addition, the number of layers contributing to the electron–phonon interaction, which is measured in an atom surface collision. 相似文献
53.
湖南某铀矿为我国一重要铀资源生产基地,长年的矿冶活动使该铀矿冶地域生态环境不可避免地遭到了一定程度破坏。本文以该铀矿冶地域介形类为研究对象,分析其分布与生态特征,并利用该生物评价本矿冶地域地表水放射性污染状况。结果表明,Cypridopsis vidua在溪流与河流中均有分布,Helerocypris incongruens仅发现于河流,两者丰度均不高。利用该两种介形类丰度及总丰度变化可指示水体铀浓度的变化,丰度越小,铀含量越大,反之亦然。Shannon-Wiener物种多样性指数与水体铀浓度呈明显负相关,表明也可利用介形类生物指数指示水体铀浓度。该生物指数明显偏低,说明该铀矿冶地域地表水环境质量需要改善,放射性污染应引起足够重视。 相似文献
54.
55.
T.P. Rashid K. Arun Ivan Curlik Sergej Ilkovic Marian Reiffers Andrea Dzubinska R. Nagalakshmi 《中国稀土学报(英文版)》2019,37(1):74-79
We report the results of magnetic, thermodynamic, transport and magnetocaloric effect (MCE) studies of newly synthesized Gd_(10)Co_(20)Si_(70) alloy. These measurements confirm an antiferromagnetic transition at T_N=9 K. Both MCE and magnetoresistance (MR) show quadratic dependence on the applied magnetic field, indicating the presence of spin fluctuations in the alloy. The maximum values of the magnetic entropy change determined from the isothermal magnetization data for magnetic field change of 7 and9 T are found to be 10.5 and 15.6 J/kg·K, respectively. As a consequence of the spin fluctuations effect, the MCE peaks are pulled towards high temperature side as asymmetrically broadened peak. The MR attains a large positive value of 73%at 2 K in 8 T. The large MR and reversible MCE make this alloy an attractive multifunctional magnetic material. 相似文献
56.
57.
《Calphad》2019
Temperature coefficient of surface tension is a very important parameter to calculate phase diagrams of nanoparticle metal systems. In this paper, neural network calculation was for the first time used to evaluate the temperature coefficient. It shows that the constructed neural network can predict the temperature coefficient values for 37 metals, with the deviation from the averaged experimental measurements smaller than 25%. Furthermore, the neural network predictions were compared with the calculated values by using an empirical equation and it shows a better performance. 相似文献
58.
Metal injection moulding (MIM) is an established process for high volume production of complex shaped metallic parts using commercially available feedstocks. The characteristics of parts after moulding, debinding, and sintering cannot be simply predictable from raw materials because the properties get altered with the process parameters and the corresponding levels of porosity during processing steps. In this study, physical properties, microstructure, and mechanical properties of the MIM parts have been characterised to understand the evolution of strength during various steps in MIM processing. Feedstocks with different binder loading show a considerable difference in physical as well as mechanical characteristics. During sintering of parts which have solid loading of grinding sludge, simultaneous in situ reduction and densification takes place, whereas only densification occurs in carbonyl iron parts. It is, therefore, possible to make complex shaped parts of different levels of porosity from downgraded shop floor metallic waste. 相似文献
59.
In finding what physiological characteristics can be used to predict ground cover success on mine reclamation sites, 14 herb and grass species were tested. Establishment and early growth was tested on three different soils, ie vermiculate and quartz sand mixture, quarry overburden and coal mine overburden in a greenhouse. The results indicate that plant height and cover, transpiration rate and foliar pigments may be used to select plant adaptability to mined soil. White clover (Trifolium repens L.) showed the greatest potential as ground cover for mined soils. Species most widely used in reclamation tended to be perennials of moderate rate. 相似文献
60.
Tatsuro Tanaka Yoshifumi Maeda Shinji Yamamoto Toru Iwao 《Electrical Engineering in Japan》2019,207(1):15-23
The arc welding has been used in various welding methods because it is inexpensive and high in strength after welding. However, it is a problem that accidents such as collapse of the bridge occur because of the welding defects. The welding of low cost and high productivity is required without the welding defects. The pulsed TIG welding is inexpensive and capable of high‐quality welding. The electromagnetic force contributing to penetration changes because the transient response of arc temperature and iron vapor generated from anode occurs. However, the analysis of pulsed TIG welding with metal vapor has been elucidated only metal vapor concentration near anode with transient phenomenon and heat flux. Thus, the theoretical elucidation of penetration depth with control factor has not been researched. In this paper, the contribution of metal vapor mass at the periphery part of pulsed arc to the electromagnetic force in the weld pool is elucidated. As a result, the iron vapor mass at periphery part decreased with increasing the frequency. The iron vapor was stagnated at axial center within one cycle. The electromagnetic force to the penetration depth direction in weld pool increased at axial center. Therefore, the metal vapor mass at periphery part plays an important role for the electromagnetic force increment at axial center. 相似文献